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41,371,582 | https://en.wikipedia.org/wiki/Aspergillus%20restrictus | Aspergillus restrictus is a species of fungus in the genus Aspergillus. It is from the Restricti section. The species was first described in 1931. It is xerophilic, frequently found in house dust. Studies have suggested that it is an allergen implicated in asthma. In 2016, the genome of A. restrictus was sequenced as a part of the Aspergillus whole-genome sequencing project - a project dedicated to performing whole-genome sequencing of all members of the genus Aspergillus. The genome assembly size was 23.26 Mbp.
Growth and morphology
A. restrictus has been cultivated on both Czapek yeast extract agar (CYA) plates and Malt Extract Agar Oxoid (MEAOX) plates. The growth morphology of the colonies can be seen in the pictures below.
References
Fungi described in 1931
restrictus
Fungus species | Aspergillus restrictus | [
"Biology"
] | 186 | [
"Fungi",
"Fungus species"
] |
59,184,147 | https://en.wikipedia.org/wiki/Residue-to-product%20ratio | In climate engineering, the residue-to-product ratio (RPR) is used to calculate how much unused crop residue might be left after harvesting a particular crop. Also called the residue yield or straw/grain ratio, the equation takes the mass of residue divided by the mass of crop produced, and the result is dimensionless.
The RPR can be used to project costs and benefits of bio-energy projects, and is crucial in determining financial sustainability. The RPR is particularly important for estimating the production of biochar, a beneficial farm input obtained from crop residues through pyrolysis. However, it is important to note that RPR values are rough estimates taken from broad production statistics, and can vary greatly depending on crop variety, climate, processing, and residual moisture content.
See also
Carbon sequestration
Biomass
Biochar
Biofuel
Pyrolysis
References
Climate engineering
Crops
Biofuels | Residue-to-product ratio | [
"Engineering"
] | 185 | [
"Planetary engineering",
"Geoengineering"
] |
59,184,609 | https://en.wikipedia.org/wiki/Ibogaline | Ibogaline is an alkaloid found in Tabernanthe iboga along with the related chemical compounds ibogaine, ibogamine, and other minor alkaloids. It is a relatively smaller component of Tabernanthe iboga root bark total alkaloids (TA) content. It is also present in Tabernaemontana species such as Tabernaemontana australis which shares similar ibogan-biosynthetic pathways. The percentage of ibogaline in T. iboga root bark is up to 15% TA with ibogaine constituting 80% of the alkaloids and ibogamine up to 5%.
Chemistry
Derivatives
Kisantine and Gabonine are thought to be ibogaline's oxidation byproducts.
Adverse effect
In rodents, ibogaline induces more body tremor and ataxia compared to ibogaine and ibogamine. Among a series of iboga and harmala alkaloids evaluated in rats, the study authors found the following order of potency in causing tremors:
ED50 (μmol/kg, sc): tabernanthine (4.5) > ibogaline (7.6) > harmaline (12.8) > harmine (13.7) > ibogaine (34.8) > noribogaine (176.0)
A subsequent study confirmed these findings.
See also
Coronaridine
Voacangine
References
Alkaloids found in Iboga
Indole alkaloids | Ibogaline | [
"Chemistry"
] | 312 | [
"Alkaloids by chemical classification",
"Indole alkaloids"
] |
59,185,446 | https://en.wikipedia.org/wiki/Carrier%20aggregation | In wireless communication, carrier aggregation is a technique used to increase the data rate per user, whereby multiple frequency blocks (called component carriers) are assigned to the same user. The maximum possible data rate per user is increased the more frequency blocks are assigned to a user. The sum data rate of a cell is increased as well because of a better resource utilization. In addition, load balancing is possible with carrier aggregation. Channel selection schemes for CA systems taking into account the optimal values for the training length and power, the number of the probed sub-channels and the feedback threshold such that the sum rate is also important for optimal achievable capacity.
Types of carrier aggregation
Depending on the positions of the component carriers three cases of carrier aggregation are distinguished:
The case where the component carriers are contiguous in the same frequency band is called intra-band contiguous carrier aggregation.
If the component carriers are in the same frequency band but are separated by a gap the carrier aggregation is called intra-band non-contiguous.
The most complex case is when the component carriers lie in different frequency band. This is called inter-band carrier aggregation applied to heterogeneous networks.
There is no difference between these three cases from a baseband perspective. However, the complexity from a radio frequency (RF) point of view is increased in the case inter-band carrier aggregation.
Applications
UMTS/HSPA+
The channel bandwidth for UMTS/HSPA+ is about 3.8 MHz with a carrier spacing of 5 MHz. Carrier aggregation is also called Dual Cell in the context of UMTS/HSPA+.
Through carrier aggregation (part of the UMTS extension HSPA+) two downlink carriers may be assigned to one user since Release 8. Release 10 supports four-carrier aggregation and eight-carrier-aggregation is supported since Release 11. 3GPP standardized carrier aggregation for HSPA+ for the uplink for up to two component carriers since Release 9.
LTE/LTE-Advanced
LTE supports since its first release channel bandwidths of 1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz and 20 MHz. Since LTE-Advanced Rel. 10 any two channels (of possibly different bandwidths) may be aggregated and be assigned to a single user. A difference between two aggregated 10 MHz component carriers and a single ordinary 20 MHz channel is that in the case of carrier aggregation the control information is transmitted on both component carriers.
LTE Advanced with carrier aggregation allows Gigabit LTE. This is made possible through higher-order modulation (256QAM), carrier aggregation and 4x4 MIMO. Since LTE Release 10 up to 5 component carriers may be aggregated, allowing for transmission bandwidths of up to 100 MHz. Using five aggregated component carriers, MIMO and 256QAM allows theoretical data rates of up to 2 gigabits per second. A management architecture that can aggregate particular systems, networks, and terminals in view of better managing the collection of available resources on a heterogeneous system level, taking into account all systems', networks', and terminals' traffic requirements and technical capabilities is considered for LTE-A system with potential deployment to 5G networks.
References
Wireless networking | Carrier aggregation | [
"Technology",
"Engineering"
] | 656 | [
"Wireless networking",
"Computer networks engineering"
] |
59,185,557 | https://en.wikipedia.org/wiki/Truncated%20triakis%20octahedron | The truncated triakis octahedron, or more precisely an order-8 truncated triakis octahedron, is a convex polyhedron with 30 faces: 8 sets of 3 pentagons arranged in an octahedral arrangement, with 6 octagons in the gaps.
Triakis octahedron
It is constructed from a triakis octahedron by truncating the order-8 vertices. This creates 6 regular octagon faces, and leaves 24 mirror-symmetric pentagons.
Octakis truncated cube
The dual of the order-8 truncated triakis octahedron is called a octakis truncated cube. It can be seen as a truncated cube with octagonal pyramids augmented to the faces.
See also
Truncated triakis tetrahedron
Truncated tetrakis cube
Truncated triakis icosahedron
External links
George Hart's Polyhedron generator - "t8kO" (Conway polyhedron notation)
Polyhedra
Truncated tilings | Truncated triakis octahedron | [
"Physics"
] | 202 | [
"Tessellation",
"Truncated tilings",
"Symmetry"
] |
59,185,608 | https://en.wikipedia.org/wiki/Truncated%20triakis%20icosahedron | The truncated triakis icosahedron, or more precisely an order-10 truncated triakis icosahedron, is a convex polyhedron with 72 faces: 10 sets of 3 pentagons arranged in an icosahedral arrangement, with 12 decagons in the gaps.
Triakis icosahedron
It is constructed from a triakis icosahedron by truncating the order-10 vertices. This creates 12 regular decagon faces, and leaves 60 mirror-symmetric pentagons.
Decakis truncated dodecahedron
The dual of the truncated triakis icosahedron is called a decakis truncated dodecahedron. It can be seen as a truncated dodecahedron with decagonal pyramids augmented to the faces.
See also
Truncated triakis tetrahedron
Truncated triakis octahedron
Truncated tetrakis cube
External links
George Hart's Polyhedron generator - "t10kI" (Conway polyhedron notation)
Polyhedra
Truncated tilings | Truncated triakis icosahedron | [
"Physics"
] | 202 | [
"Tessellation",
"Truncated tilings",
"Symmetry"
] |
59,186,680 | https://en.wikipedia.org/wiki/NGC%207606 | NGC 7606 is a spiral galaxy located in the constellation Aquarius. It is located at a distance of circa 100 million light years from Earth, which, given its apparent dimensions, means that NGC 7606 is about 165,000 light years across. It was discovered by William Herschel on September 28, 1785. The galaxy is included in the Herschel 400 Catalogue. It lies 45 arcminutes northeast from psi2 Aquarii. It can be seen with a 4 inch telescope but its visibility is greatly affected by light pollution.
Characteristics
NGC 7606 is a spiral galaxy seen on inclination. It has a bright nucleus surrounded by a prominent bulge, which is seen elliptical due to the inclination. No bar has been observed. A ring with an apparent diameter of 0.85 arcminutes has been detected at the central part of the galaxy. The galaxy features two main arms, that can be traced for nearly 360°, and several arm fragments. The arms are smooth and rather tight, although not as tightly wound as the ones of NGC 488. Few bright spots have been observed in the arms. The galaxy is found to host a supermassive black hole, whose mass based on bulge velocity dispersion σ is estimated to be 15-22 million . NGC 7606 is an isolated galaxy.
Supernovae
Two supernovae have been observed in NGC 7606:
SN 1965M (type unknown, mag. 16) was discovered by Paul Wild on 4 October 1965.
SN 1987N (type Ia, mag. 13.8) was discovered by Robert Evans on 14 December 1987.
Gallery
References
External links
Unbarred spiral galaxies
Aquarius (constellation)
7606
71047
Astronomical objects discovered in 1785
Discoveries by William Herschel | NGC 7606 | [
"Astronomy"
] | 354 | [
"Constellations",
"Aquarius (constellation)"
] |
59,186,835 | https://en.wikipedia.org/wiki/Abivax | Abivax SA is a clinical stage biotechnology company focused on developing innovative treatments that harness the body’s natural regulatory mechanisms to modulate the immune response in patients with chronic inflammatory diseases.
Abivax has one program in clinical development with its lead drug candidate, obefazimod (formerly ABX464), to treat ulcerative colitis. Another program in Crohn’s disease is also in preparation and other potential inflammatory indications are being evaluated.
The company’s headquarters are based in Paris, France with a US office in Waltham, MA. Abivax’s R&D work is conducted at its research center based in Montpellier, France.
Founding and IPO
Abivax has been founded in December 2013 in Paris.
In 2015, Abivax launched its initial public offering on the stock market Euronext in Paris, raising EUR 57.7m, a record amount for a French biotechnology company on the Euronext in Paris.
In October 2023, Abivax launched its initial public offering on the Nasdaq Global Market in the US, raising EUR 232.3m, the largest ever US IPO of a French listed biotech.
Initially, Abivax focused on the development of a novel treatment in HIV with lead drug candidate obefazimod. As the molecule showed a strong anti-inflammatory effect in preclinical models, Abivax decided to conduct a Phase 2a clinical study in ulcerative colitis, an inflammatory bowel disease (IBD). Based on the promising results of this clinical study in ulcerative colitis, the company decided to shift its focus towards the treatment of chronic inflammatory diseases.
Pipeline
Obefazimod in inflammatory diseases
Abivax focuses on the treatment of inflammatory bowel diseases, namely ulcerative colitis (UC) and Crohn’s disease (CD).
Its lead drug candidate, obefazimod, is an oral, first-in-class, small molecule that has demonstrated safety and tolerability as well as profound anti-inflammatory activity in preclinical as well as clinical trials in UC.
Obefazimod for the treatment of ulcerative colitis
Abivax’s lead drug candidate, obefazimod, has completed Phase 2a and Phase 2b clinical induction trials, investigating its anti-inflammatory effect and its potential ability to treat adults with moderately to severely active ulcerative colitis (UC), as well as the corresponding follow-on open label extension studies.
Obefazimod is currently in Phase 3 clinical trials for the treatment of moderately to severely active ulcerative colitis ("ABTECT program").
1,200 UC patients across 36 countries in over 600 study sites will take part in the pivotal Phase 3 program that covers North America, Europe, Latin America, and Asia Pacific.
Obefazimod for the treatment of Crohn’s disease
Based on the encouraging safety profile and efficacy results observed with obefazimod in UC, Abivax is planning to initiate a Phase 2a clinical trial for the treatment of CD.
Abivax research activities
Abivax is conducting all R&D work in Montpellier where half of the company’s staff is based at its collaborative laboratory. The scientists in Montpellier closely collaborate with the French National Center for Scientific Research (CNRS), the Institut Curie and the University of Montpellier.
References
2015 initial public offerings
Biotechnology companies established in 2013
Biotechnology companies of France
Companies based in Paris
Companies listed on Euronext Paris
French companies established in 2013
Life sciences industry
Pharmaceutical companies established in 2013
Pharmaceutical companies of France
"Abivax provides 2024 strategic outlook and lays out key milestones over next 12 months". BioSpace. 2024-01-22. Retrieved 2024-07-24. | Abivax | [
"Biology"
] | 785 | [
"Life sciences industry"
] |
59,188,974 | https://en.wikipedia.org/wiki/Localization-protected%20quantum%20order | Many-body localization (MBL) is a dynamical phenomenon which leads to the breakdown of equilibrium statistical mechanics in isolated many-body systems. Such systems never reach local thermal equilibrium, and retain local memory of their initial conditions for infinite times. One can still define a notion of phase structure in these out-of-equilibrium systems. Strikingly, MBL can even enable new kinds of exotic orders that are disallowed in thermal equilibrium – a phenomenon that goes by the name of localization-protected quantum order (LPQO) or eigenstate order.
Background
The study of phases of matter and the transitions between them has been a central enterprise in physics for well over a century. One of the earliest paradigms for elucidating phase structure, associated most with Landau, classifies phases according to the spontaneous breaking of global symmetries present in a physical system. More recently, we have also made great strides in understanding topological phases of matter which lie outside Landau's framework: the order in topological phases cannot be characterized by local patterns of symmetry breaking, and is instead encoded in global patterns of quantum entanglement.
All of this remarkable progress rests on the foundation of equilibrium statistical mechanics. Phases and phase transitions are only sharply defined for macroscopic systems in the thermodynamic limit, and statistical mechanics allows us to make useful predictions about such macroscopic systems with many (~ 1023) constituent particles. A fundamental assumption of statistical mechanics is that systems generically reach a state of thermal equilibrium (such as the Gibbs state) which can be characterized by only a few parameters such as temperature or a chemical potential. Traditionally, phase structure is studied by examining the behavior of ``order parameters" in equilibrium states. At zero temperature, these are evaluated in the ground state of the system, and different phases correspond to different quantum orders (topological or otherwise). Thermal equilibrium strongly constrains the allowed orders at finite temperatures. In general, thermal fluctuations at finite temperatures reduce the long-ranged quantum correlations present in ordered phases and, in lower dimensions, can destroy order altogether. As an example, the Peierls-Mermin-Wagner theorems prove that a one dimensional system cannot spontaneously break a continuous symmetry at any non-zero temperature.
Recent progress on the phenomenon of many-body localization has revealed classes of generic (typically disordered) many-body systems which never reach local thermal equilibrium, and thus lie outside the framework of equilibrium statistical mechanics. MBL systems can undergo a dynamical phase transition to a thermalizing phase as parameters such as the disorder or interaction strength are tuned, and the nature of the MBL-to-thermal phase transition is an active area of research. The existence of MBL raises the interesting question of whether one can have different kinds of MBL phases, just as there are different kinds of thermalizing phases. Remarkably, the answer is affirmative, and out-of-equilibrium systems can also display a rich phase structure. What's more, the suppression of thermal fluctuations in localized systems can even allow for new kinds of order that are forbidden in equilibrium—which is the essence of localization-protected quantum order. The recent discovery of time-crystals in periodically driven MBL systems is a notable example of this phenomenon.
Phases out of equilibrium: eigenstate order
Studying phase structure in localized systems requires us to first formulate a sharp notion of a phase away from thermal equilibrium. This is done via the notion of eigenstate order: one can measure order parameters and correlation functions in individual energy eigenstates of a many-body system, instead of averaging over several eigenstates as in a Gibbs state. The key point is that individual eigenstates can show patterns of order that may be invisible to thermodynamic averages over eigenstates. Indeed, a thermodynamic ensemble average isn't even appropriate in MBL systems since they never reach thermal equilibrium. What's more, while individual eigenstates aren't themselves experimentally accessible, order in eigenstates nevertheless has measurable dynamical signatures. The eigenspectrum properties change in a singular fashion as the system transitions between from one type of MBL phase to another, or from an MBL phase to a thermal one---again with measurable dynamical signatures.
When considering eigenstate order in MBL systems, one generally speaks of highly excited eigenstates at energy densities that would correspond to high or infinite temperatures if the system were able to thermalize. In a thermalizing system, the temperature is defined via where the entropy is maximized near the middle of the many-body spectrum (corresponding to ) and vanishes near the edges of the spectrum (corresponding to ). Thus, "infinite temperature eigenstates" are those drawn from near the middle of the spectrum, and it more correct to refer to energy-densities rather than temperatures since temperature is only defined in equilibrium. In MBL systems, the suppression of thermal fluctuations means that the properties of highly excited eigenstates are similar, in many respects, to those of ground states of gapped local Hamiltonians. This enables various forms of ground state order to be promoted to finite energy densities.
We note that in thermalizing MB systems, the notion of eigenstate order is congruent with the usual definition of phases. This is because the eigenstate thermalization hypothesis (ETH) implies that local observables (such as order parameters) computed in individual eigenstates agree with those computed in the Gibbs state at a temperature appropriate to the energy density of the eigenstate. On the other hand, MBL systems do not obey the ETH and nearby many-body eigenstates have very different local properties. This is what enables individual MBL eigenstates to display order even if thermodynamic averages are forbidden from doing so.
Localization-protected symmetry-breaking order
Localization enables symmetry breaking orders at finite energy densities, forbidden in equilibrium by the Peierls-Mermin-Wagner Theorems.
Let us illustrate this with the concrete example of a disordered transverse field Ising chain in one dimension:
where are Pauli spin-1/2 operators in a chain of length , all the couplings are positive random numbers drawn from distributions with means , and the system has Ising symmetry corresponding to flipping all spins in the basis. The term introduces interactions, and the system is mappable to a free fermion model (the Kitaev chain) when .
Non-interacting Ising chain – no disorder
Let us first consider the clean, non-interacting system: . In equilibrium, the ground state is ferromagnetically ordered with spins aligned along the axis for , but is a paramagnet for and at any finite temperature (Fig 1a). Deep in the ordered phase, the system has two degenerate Ising symmetric ground states which look like ``Schrödinger cat" or superposition states: . These display long-range order:
At any finite temperature, thermal fluctuations lead to a finite density of delocalized domain walls since the entropic gain from creating these domain walls wins over the energy cost in one dimension. These fluctuations destroy long-range order since the presence of fluctuating domain walls destroys the correlation between distant spins.
Disordered non-interacting Ising chain
Upon turning on disorder, the excitations in the non-interacting model () localize due to Anderson localization. In other words, the domain walls get pinned by the disorder, so that a generic highly excited eigenstate for looks like , where refers to the eigenstate and the pattern is eigenstate dependent. Note that a spin-spin correlation function evaluated in this state is non-zero for arbitrarily distant spins, but has fluctuating sign depending on whether an even/odd number of domain walls are crossed between two sites. Whence, we say that the system has long-range spin-glass (SG) order. Indeed, for , localization promotes the ground state ferromagnetic order to spin-glass order in highly excited states at all energy densities (Fig 1b). If one averages over eigenstates as in the thermal Gibbs state, the fluctuating signs causes the correlation to average out as required by Peierls theorem forbidding symmetry breaking of discrete symmetries at finite temperatures in 1D. For , the system is paramagnetic (PM), and the eigenstates deep in the PM look like product states in the basis and do not show long range Ising order: . The transition between the localized PM and the localized SG at belongs to the infinite randomness universality class.
Disordered interacting Ising chain
Upon turning on weak interactions , the Anderson insulator remains many-body localized and order persists deep in the PM/SG phases. Strong enough interactions destroy MBL and the system transitions to a thermalizing phase. The fate of the MBL PM to MBL SG transition in the presence of interactions is presently unsettled, and it is likely this transition proceeds via an intervening thermal phase (Fig 1c).
Detecting eigenstate order – measurable signatures
While the discussion above pertains to sharp diagnostics of LPQO obtained by evaluating order parameters and correlation functions in individual highly excited many-body eigenstates, such quantities are nearly impossible to measure experimentally. Nevertheless, even though individual eigenstates aren't themselves experimentally accessible, order in eigenstates has measurable dynamical signatures. In other words, measuring a local physically accessible observable in time starting from a physically preparable initial state still contains sharp signatures of eigenstate order.
For example, for the disordered Ising chain discussed above, one can prepare random symmetry-broken initial states which are product states in the basis: . These randomly chosen states are at infinite temperature. Then, one can measures the local magnetization in time, which acts as an order parameter for symmetry breaking. It is straightforward to show that saturates to a non-zero value even for infinitely late times in the symmetry-broken spin-glass phase, while it decays to zero in the paramagnet. The singularity in the eigenspectrum properties at the transition between the localized SG and PM phases translates into a sharp dynamical phase transition which is measurable. Indeed, a nice example of this is furnished by recent experiments detecting time-crystals in Floquet MBL systems, where the time crystal phase spontaneously breaks both time translation symmetry and spatial Ising symmetry, showing correlated spatiotemporal eigenstate order.
Localization-protected topological order
Similar to the case of symmetry breaking order, thermal fluctuations at finite temperatures can reduce or destroy the quantum correlations necessary for topological order. Once again, localization can enable such orders in regimes forbidden by equilibrium. This happens for both the so-called long range entangled topological phases, and for symmetry protected or short-range entangled topological phases. The toric-code/ gauge theory in 2D is an example of the former, and the topological order in this phase can be diagnosed by Wilson loop operators. The topological order is destroyed in equilibrium at any finite temperature due to fluctuating vortices--- however, these can get localized by disorder, enabling glassy localization-protected topological order at finite energy densities. On the other hand, symmetry protected topological (SPT) phases do have any bulk long-range order, and are distinguished from trivial paramagnets due to the presence of coherent gapless edge modes as long the protecting symmetry is present. In equilibrium, these edge modes are typically destroyed at finite temperatures as they decohere due to interactions with delocalized bulk excitations. Once again, localization protects the coherence of these modes even at finite energy densities! The presence of localization-protected topological order could potentially have far-reaching consequences for developing new quantum technologies by allowing for quantum coherent phenomena at high energies.
Floquet systems
It has been shown that periodically driven or Floquet systems can also be many-body localized under suitable drive conditions. This is remarkable because one generically expects a driven many-body system to simply heat up to a trivial infinite temperature state (the maximum entropy state without energy conservation). However, with MBL, this heating can be evaded and one can again get non-trivial quantum orders in the eigenstates of the Floquet unitary, which is the time-evolution operator for one period. The most striking example of this is the time-crystal, a phase with long-range spatiotemporal order and spontaneous breaking of time translation symmetry. This phase is disallowed in thermal equilibrium, but can be realized in a Floquet MBL setting.
References
Quantum mechanics
Quantum chaos theory | Localization-protected quantum order | [
"Physics"
] | 2,656 | [
"Theoretical physics",
"Quantum mechanics"
] |
59,190,308 | https://en.wikipedia.org/wiki/Mircea%20Dinc%C4%83 | Mircea Dincă (born 1980) is a Romanian-American inorganic chemist. He is the Andrew Stewart 1886 Professor of Chemistry at Princeton University. At Princeton, Dincă leads a research group that focuses on the synthesis of functional metal-organic frameworks (MOFs), which possess conductive, catalytic, and other material-favorable properties.
Early life and education
Mircea Dincă was born in Făgăraș, Romania. His passion for chemistry began in his chemistry class in 7th grade, where he had a "dedicated teacher that did spectacular demonstrations with relatively limited regard for safety". In 1998, he represented Romania at the International Science Olympiad (Chemistry) in Yakutsk, Russia, where he won first prize.
After high school, Dincă was offered a scholarship from Princeton University and moved to New Jersey in 1999. At Princeton, he worked with Jeffrey Schwartz, conducting research on materials science. After graduating magna cum laude in 2003, Dincă went on to the University of California, Berkeley to attend the Chemistry doctorate program, where he worked with chemistry professor Jeffrey R. Long on increasing H2 adsorption in metal-organic frameworks with mobile hydrogen storage applications. He graduated with his Ph.D. from Berkeley in 2008.
Career
Dincă completed his postdoc studies at MIT, where he was promoted to associate professor in 2010 and, in 2017, tenured. Until 2024, he was the W. M. Keck Professor of Chemistry. In 2025, he joined the faculty at Princeton University.
Research
Dincă's research primarily focuses on electrical conductivity of MOF's, which was previously unknown and resulted in a new categorization of such materials with "charge mobility values". His focus is on the exploration of increasing electrical conductivity capacities through the marriage of organic and inorganic materials to assemble hybrid MOF's.
Research includes exploring electrochemical cycling through strongly adhering, electroactive metal–organic framework thin films to vary results, such as multicolored electrochromic responses and transparent to dark behavior.
References
1980 births
Living people
People from Făgăraș
Romanian chemists
21st-century Romanian scientists
21st-century American chemists
Princeton University alumni
University of California, Berkeley alumni
Massachusetts Institute of Technology School of Science faculty
Sloan Research Fellows
Romanian expatriates in the United States
Expatriate academics in the United States
Solid state chemists | Mircea Dincă | [
"Chemistry"
] | 482 | [
"Solid state chemists"
] |
59,190,719 | https://en.wikipedia.org/wiki/Dorothy%20Hill%20Medal | The Dorothy Hill Medal is awarded annually and honours the contributions of Dorothy Hill to Australian Earth science and her work in opening up tertiary science education to women.
The award supports research in the Earth sciences by female researchers up to 10 years post doctorate for research carried out mainly in Australia.
Prior to 2018 the award was known as the Dorothy Hill Award.
Recipients
Source: Australian Academy of Science
See also
List of earth sciences awards
References
Earth sciences awards
Australian Academy of Science Awards
Australian science and technology awards
Awards established in 2002
Science awards honoring women | Dorothy Hill Medal | [
"Technology"
] | 106 | [
"Science and technology awards",
"Earth sciences awards",
"Science awards honoring women"
] |
59,191,356 | https://en.wikipedia.org/wiki/Auguste%20Rateau | Auguste Rateau (; 13 October 1863 – 13 January 1930) was an engineer and industrialist born in Royan, France, specializing in turbines.
Biography
After studies, first at the École Polytechnique and then at the École des Mines de Paris, he began his career as a teacher at the École des Mines de Saint-Étienne from 1888 to 1897.
He then embarked on an industrial career exploiting turbines. He manufactured fans for mines, blowers for steel mills, water pumps, and steam turbines for ships. To this end, he created a design office in Paris and, in 1903, the Société pour l’exploitation des appareils Rateau, which moved in 1917 to La Courneuve where he opened a factory two years later. The company has since been integrated into Alstom, and La Courneuve's premises are still operated by GE Power Service. This entity manages the maintenance of turbomachines, turbo-pumps and turbocompressors installed on nuclear, thermal and industrial sites in France and in some parts of the world.
In 1928 he founded the Association Française de Normalisation, the French national organization for standardization, and served as president.
Rateau was a Commander of the Legion of Honour () and a member of the French Academy of Sciences ().
1863 births
1930 deaths
People from Royan
20th-century French engineers
20th-century French inventors
Steam turbines
Turbines
Members of the French Academy of Sciences
École Polytechnique alumni
Commanders of the Legion of Honour
Mines Paris - PSL alumni | Auguste Rateau | [
"Chemistry"
] | 310 | [
"Turbines",
"Turbomachinery"
] |
59,197,709 | https://en.wikipedia.org/wiki/Abir%20Al-Tabbaa | Abir Al-Tabbaa is a Professor of Civil and Environmental Engineering at the University of Cambridge. She works on intelligent materials for infrastructure. She is the Director of the Future Infrastructure and Built Environment Doctoral Training Centre.
Early life and education
Al-Tabbaa studied at the University of Bristol. She completed her Master's and doctoral degrees at the University of Cambridge, working on the stress-strain responses of Kaolinite. Her Master's research considered the anisotropy of clay. She obtained her PhD in 1987 with a dissertation entitled Permeability and stress-strain response of speswhite kaolin. After graduating Al-Tabbaa worked at Ove Arup & Partners as a geotechnical engineer. She was involved with the construction of the Charing Cross railway station and Ludgate Hill railway station. In 1991 she joined the University of Birmingham as a lecturer.
Research
Al-Tabbaa returned to the University of Cambridge in 1997 and was made a Fellow of Sidney Sussex College. Her work concentrates on the development and testing of materials for civil engineering. She is interested in low-carbon infrastructure and the remediation of contaminated land. She also works on soil mix technology and water valorisation. She has developed new techniques for the characterisation of soils. She has over 300 publications. In 2003 she was awarded the Institution of Civil Engineers' Mallik Medal for her work on the five-year soil treatment mixing work at West Drayton.
She was part of a £1.67 million Engineering and Physical Sciences Research Council project that established the Centre of Excellence on Intelligent Construction Materials to reduce the cost of infrastructure maintenance of future construction. The project was followed up with an EPSRC Programme Grant on resilient materials for life. Amongst other biomimetic materials, the collaboration developed self-healing concrete. She spoke about their work at the World Economic Forum in 2016.
Academic service
She has written for the New Civil Engineer. Al-Tabbaa has served on the British Geotechnical Association Executive Committee, the Institution of Civil Engineers' Geotechnical Advisory Panel and the Grounded Improvement Advisory Panel. In 2014 she became the Director of the Future Infrastructure and Built Environment Doctoral Training Centre. She serves on the editorial board of the American Society of Civil Engineers Journal of Materials in Civil Engineering. She is also the UK representative for the Self-healing as Preventative Repair of Concrete Structures (SARCOS) European Cooperation in Science and Technology Action. She was elected a Fellow of the Institution of Civil Engineers in 2014, recognising her significant contributions to both research and education in civil engineering. In 2016 she was part of a group of academics from the University of Cambridge who wrote to The Daily Telegraph to stress the need for European funding for scientific research. Al-Tabbaa appeared on the BBC Radio Cambridgeshire programme The Naked Scientists.
Books
2010 Rainfall Trends in India and Their Impact on Soil Erosion: Rainfall Trends in India and Their Impact on Soil Erosion
2005 Stabilisation/Solidification Treatment and Remediation
References
Year of birth missing (living people)
Living people
British women engineers
Fellows of Sidney Sussex College, Cambridge
Academics of the University of Birmingham
Environmental scientists
English civil engineers
Engineering professors at the University of Cambridge | Abir Al-Tabbaa | [
"Environmental_science"
] | 652 | [
"Environmental scientists",
"British environmental scientists"
] |
59,199,575 | https://en.wikipedia.org/wiki/Beyond%20Curie | Beyond Curie is a portrait series of women who have made significant contributions in STEM fields. As of November 2018, the series features 42 women, including all 18 female Nobel Prize winners in Physics, Chemistry, and Physiology or Medicine.
The series was created by Amanda Phingbodhipakkiya, a former neuroscience researcher and designer who named the project after two-time Nobel prize winner Marie Curie, with the goal of highlighting other important female scientists who are less well known. Beyond Curie has raised $44,172 from 856 backers across two Kickstarter campaigns.
Public exhibits
Beyond Curie has been on display in an exhibit at the North Carolina Museum of Natural Sciences since March 24, 2017.
Phingbodhipakkiya worked with the March for Science organizers to make special Beyond Curie posters that could be freely downloaded and brought to a rally or protest.
In partnership with Outside, Phingbodhipakkiya developed five portraits specifically focused on women whose work focused on health and the environment.
Phingbodhipakkiya presented some of the Beyond Curie portraits at TEDWomen 2017, where she said the project was "about finding your heroes" and shared stories of female scientists who only learned about some of the historical figures of the series after encountering Beyond Curie.
In September and November 2018, the Beyond Curie posters were displayed in a highway tunnel in Breda, Netherlands by 3 Second Gallery.
Featured women
As of December 2018, the women featured in the series are:
Lise Meitner
Katherine Johnson
Chien-Shiung Wu
Margaret Ann Bulkley
Ada Lovelace
Mae Jemison
Rita Levi-Montalcini
Barbara McClintock
Maryam Mirzakhani
Rosalyn Sussman Yalow
Françoise Barré-Sinoussi
Carol Greider
Elizabeth Blackburn
Grace Hopper
May-Britt Moser
Linda Buck
Youyou Tu
Rosalind Franklin
Jocelyn Bell Burnell
Christiane Nüsslein-Volhard
Vera Rubin
Ada Yonath
Sylvia Earle
Rachel Carson
Gertrude B. Elion
Mary Golda Ross
Irène Joliot-Curie
Dorothy Crowfoot Hodgkin
Farida Bedwei
Lisa Ng
Mildred Dresselhaus
Maria Goeppert-Mayer
Valerie Thomas
Helen Rodriguez-Trias
Esther Lederberg
Inez Fung
Florence Bascom
Dijanna Figueroa
Kalpana Chawla
Rose E. Frisch
Frances Arnold
Donna Strickland
Augmented reality
In additional to graphic illustration, Phingbodhipakkiya worked with technologists at NC State to develop 3D augmented reality animations for a number of the women, including McClintock, Greider, Blackburn, Joliot-Curie, Johnson, Buck, Ng, Jemison, Mirzakhani, Franklin, Rubin, Dresselhaus, Goeppert-Mayer, Tu, Yalow. The augmented reality animations can be seen using a free mobile app called "Beyond Curie" available on Google Play and App Store.
Recognition
Beyond Curie has won several awards, including 1st Place in Multimedia / Interactive Media in the 2017 International Design Awards and the Red Dot 2017 design award.
Phingbodhipakkiya was invited to speak about the project to the employees at Google in November 2018. The project was featured in a blog post by venture capitalist and Kickstarter board member Fred Wilson.
References
External links
Women in science and technology
Science education in the United States | Beyond Curie | [
"Technology"
] | 683 | [
"Women in science and technology"
] |
59,199,841 | https://en.wikipedia.org/wiki/NGC%207723 | NGC 7723 is a barred spiral galaxy located in the constellation Aquarius. It is located at a distance of about 90 million light years from Earth, which, given its apparent dimensions, means that NGC 7723 is about 95,000 light years across. It was discovered by William Herschel on November 27, 1785. The galaxy is included in the Herschel 400 Catalogue. It lies 1.5 degrees north-northwest from Omega1 Aquarii. It can be seen with a 4-inch telescope under dark skies.
Characteristics
NGC 7723 is a barred spiral galaxy. It has a bright nucleus and a boxy bulge. In the centre of the galaxy lies a supermassive black hole whose mass is estimated to be based on the spiral arm pitch angle. The bar emerges from the opposite sides of the bulge. Straight dust lanes are observed along the bar, the one smooth and the other appearing broken. The bar has a maximum apparent length of 64 arcseconds. At the end of the bar the spiral arms form a pseudoring with diameter of 71 arcseconds. Based on observations in far ultraviolet (FUV) and Hα there is active star formation at the pseudoring. Based on the B-I color profile of the galaxy the bar finishes at 23 arcseconds, at the same distance where there is a population of older stars, and thus is suggested to be the corotation radius of NGC 7723.
The structure of the arms is complex. The arm that emanates from the southwest part of the bar is well defined for a quarter of a revolution and after that it becomes more diffuse and fades after reaching half a revolution. The other arm emanates from a feature about 60 degrees northwest of the bar and brightens after passing the end of the bar, and then it splits in two. The inner part forms the southwest part of the pseudoring and bifurcates after winding for about 120 degrees after the bar end, with the inner part being the brightest. The other arm becomes diffuse and of low surface brightness.
One supernova has been observed in NGC 7723: SN 1975N (type Ia, mag. 15) was discovered by Paul Wild on 24 October 1975. It was also independently discovered by Valentin A. Lipovetsky on 27 October 1975.
Nearby galaxies
NGC 7723 belongs to a small groups of galaxies known as the NGC 7727 group. Other members of the group include NGC 7727 and NGC 7724. NGC 7727 lies about 40' northwest of NGC 7723.
References
External links
Barred spiral galaxies
Aquarius (constellation)
7723
72009
Astronomical objects discovered in 1785
Discoveries by William Herschel | NGC 7723 | [
"Astronomy"
] | 541 | [
"Constellations",
"Aquarius (constellation)"
] |
59,201,058 | https://en.wikipedia.org/wiki/Catherine%20Rae | Catherine Mary Fiona Rae is a Professor of Superalloys in the Department of Materials at the University of Cambridge. Rae is the Director of the Rolls-Royce UTC in Cambridge. She is known for her expertise in electron microscopy and the behaviour of materials in aerospace applications.
Education
Rae became interested in science when accompanying her father on field work visits to sub-Saharan Africa and the space race between the US and USSR. This motivated her application to University, where Rae was one of the first female students to study in St Catherine's College, Oxford (as it was previously an all-male college) and was a college scholar. In 1974, she completed her degree and received a First in Metallurgy and the Science of Materials. Rae completed her Doctor of Philosophy degree on grain boundary migration supervised by David A Smith and Peter Hazeldine.
Research and career
After her studies in the University of Oxford, Rae moved to Girton College, Cambridge to become a Rolls-Royce Research Fellow. This began her association with Rolls-Royce Holdings and her work in superalloys. In 1972, Rae received a University Fellowship sponsored by Rolls-Royce which she used to fund her research full-time for three years and part-time for two years after the birth of her son.
Rae took time out of research for the birth of, and to raise, her first daughter, and this was extended by the birth of her second daughter and the recession. In this period, Rae taught for the Open University and developed a Science Foundation course at the University of East Anglia (UEA) which was established to enable those with GCE Advanced Level qualifications to gain entry to University.
After this eight-year break, Rae rejoined the University of Cambridge and earned a lectureship position in the Department of Materials Science and Metallurgy and a teaching fellowship at Emmanuel College, Cambridge in 2002. In 2009, Rae was awarded an Industrial Fellowship hosted by Rolls-Royce plc and provided her with direct view of the workings of the company.
Rae is well known for her work on superalloys, including understanding the mechanical properties and microstructure formation, as well as the development of single crystal superalloy blade systems including the application of the thermal barrier coating. She is an expert in transmission electron microscopy. Rae holds multiple patents for significant advances in materials for gas turbine engines.
Professional service
In 2014, Rae was on the Programme Committee for EuroSuperalloys 2014, a major conference in superalloys research. Rae has served on the Royal Society Committee for Science, Industry and Translation. She is Director of the Rolls-Royce Strategic Training Partnership which was nominated for the Times Higher Education Awards in 2017 for the "Most Innovative Contribution to Business-University Collaboration". Rae is also serves as a member of the "Structure and Properties of Materials Committee" for the Institute of Materials, Minerals and Mining. In 2018 she led the Rolls-Royce UTC's presentation of "Engineering Atoms" at the Royal Society Summer Exhibition. Rae acts as Senior Advisor for the start-up "OxMet" founded by Roger Reed.
Public service
In the 2021 United Kingdom local elections Rae was elected as a Labour Party councilor for Cambridgeshire County Council, representing the Castle ward in Cambridge. Previously, in 2018 Rae had unsuccessfully run for councillor for the Fen Ditton and Fulbourn Ward of South Cambridgeshire District Council as a Labour Party Councillor.
Selected Academic Publications
Rae, Catherine MF, and Roger C. Reed. "The precipitation of topologically close-packed phases in rhenium-containing superalloys." Acta materialia 49.19 (2001): 4113-4125.
Freund, Lisa P., et al. "Segregation assisted microtwinning during creep of a polycrystalline L12-hardened Co-base superalloy." Acta Materialia 123 (2017): 295-304.
Bensch, Matthias, et al. "Influence of oxidation on near-surface γ′ fraction and resulting creep behaviour of single crystal Ni-base superalloy M247LC SX." Materials Science and Engineering: A 577 (2013): 179-188.
Pang, Hon Tong, et al. "Solution heat treatment optimization of fourth-generation single-crystal nickel-base superalloys." Metallurgical and Materials Transactions A 43.9 (2012): 3264-3282.
References
Living people
Year of birth missing (living people)
Alumni of St Catherine's College, Oxford
British metallurgists
Fellows of Emmanuel College, Cambridge
Place of birth missing (living people)
Women materials scientists and engineers
Fellows of the Institute of Materials, Minerals and Mining
Members of Cambridgeshire County Council
Labour Party (UK) councillors | Catherine Rae | [
"Materials_science",
"Technology"
] | 955 | [
"Women materials scientists and engineers",
"Materials scientists and engineers",
"Women in science and technology"
] |
59,202,139 | https://en.wikipedia.org/wiki/NGC%202835 | NGC 2835 is an intermediate spiral galaxy located in the constellation Hydra. It is located at a distance of circa 35 million light years from Earth, which, given its apparent dimensions, means that NGC 2835 is about 65,000 light years across. It was discovered by Wilhelm Tempel on April 13, 1884. NGC 2835 is located only 18.5 degrees from the galactic plane.
NGC 2835 is seen nearly face-on. The galaxy features four or five spiral arms, visible in near infrared due to their population II stars. The spiral arms have also numerous HII regions and stellar associations, the larger of which are 5 arcseconds across. Although the galaxy is quite symmetric, the northern arms have HII regions that appear brighter than the southern ones. Also the southern arms appear less developed in their outer parts than the north ones. The star formation rate in NGC 2835 is 1.3 per year and the total stellar mass of the galaxy is 1010 . In the centre of NGC 2835 lies a supermassive black hole whose mass is estimated to be 3-10 million (106.72±0.3) , based on the spiral arm pitch angle.
NGC 2835 is the foremost galaxy in a small group of galaxies, the NGC 2835 group. Other galaxies identified as members of the cluster are ESO 497-035, and ESO 565-001. A bit farther away, at projected separation of 2.2 degrees, lies NGC 2784 and its small galaxy group.
See also
NGC 5068 - another low mass spiral galaxy
References
External links
Intermediate spiral galaxies
Hydra (constellation)
2835
UGCA objects
26259
Astronomical objects discovered in 1884
Discoveries by Wilhelm Tempel | NGC 2835 | [
"Astronomy"
] | 352 | [
"Hydra (constellation)",
"Constellations"
] |
59,202,217 | https://en.wikipedia.org/wiki/Metachronal%20swimming | A metachronal swimming or metachronal rowing is the swimming technique used by animals with multiple pairs of swimming legs. In this technique, appendages are sequentially stroked in a back-to-front wave moving along the animal’s body. In literature, while metachronal rhythm or metachronal wave usually refer to the movement of cilia; metachronal coordination, metachronal beating, metachronal swimming or metachronal rowing usually refer to the leg movement of arthropods, such as mantis shrimp, copepods, antarctic krill etc. though all of them refer to the similar locomotion pattern.
Metachronous indicates something not functioning or occurring synchronously, or occurring or starting at different times. This word is derived from Greek meta- μετά- meaning, occurring later than or in succession to : after, and -chronous -Χρόνος meaning, of (such) a time or period.
Swimming legs should coordinate to avoid interference among appendage pairs. To accomplish this challenge, almost all free-swimming crustaceans adapted to some version of metachronism.
Significance
Ecologically and economically important crustaceans such as copepods, krill, shrimp, crayfish, and lobsters use metachronal swimming for locomotion. Using this technique, animals propel significant portion of earth's aquatic biomass. As an example, the biomass of a sole metachronally swimming species, the Antarctic krill Euphausia superba, is more than the total adult human biomass. Moreover, this technique is important from biomechanics point of view because it has been adapted to perform extreme swimming actions. The highest animal acceleration of 200 m/s^2, for example, belongs to the escape jump of the copepod Calanus finmarchicus. On the other hand, Antarctic krill uses metachronal swimming to efficiently migrate distances up to 10 km per day.
It is believed that, during power stroke appendages are subject to drag which creates forward thrust, during the recovery stroke appendages are folded towards body to reduce the drag. Furthermore, back-to-front swimming pattern is thought to be more efficient than front-to-back or synchronous pattern.
Examples from nature
Cilia in metazoa
Knight-Jones defines the types of metachronism in ciliary beat of metazoa depending on the relative direction of wave to the effective beat. If the effective beat is in the same direction as metachronal wave, then it is called as symplectic metachronal wave. If opposite, the wave is called antiplectic. There are cases where the wave is directed to the right or to the left of the effective beat. In these cases the metachronal wave is called dexioplectic if effective beat is to the right of the wave, and laeoplectic if effective beat is to the left of the wave.
Mantis shrimp
Mantis shrimp have five pairs of pleopods which they use to swim. Kinematics of their swimming reveals a metachronal pattern. A study by Campos et al. showed that the power stroke of the mantis shrimp (Odontodactylus havanensis) is metachronal, creating a back-to-front wave motion. While the power stroke is completed metachronally, the recovery stroke occurs nearly synchronously. The same rowing pattern was observed by another study. Stein et al. also report the metachronal rowing in mantis shrimp in their study
Copepods
Metachronism in copepods was observed by numerous studies. Copepods show metachronal beating pattern while foraging and escape movements. In this study by van Duren and Videler, it was observed that during foraging, copepods metachronally beat their first three mouth appendages (antennae, mandibular palps and maxillules) creating backward motion of water. During escape, their mouth appendages stop moving and swimming legs beat in a very fast metachronal rhythm, accelerating a jet of water backwards.
Slow-motion video by Jiang and Kiorboe reveals the metachronal beating of legs of cyclopoid copepod Oithona davisae during jumping. In this video, last pair of legs initiate the power stroke followed by the adjacent pair. Power stroke ends with the first pair. While power stroke is metachronal, recovery stroke is near synchronous.
Antarctic krill
Antarctic krill swim in a metachronal rhythm. They use several swimming modes, including hovering, fast-forward swimming and upside-down swimming, with differing kinematics. Hovering (HOV), is the swimming mode corresponding to body angles between 25 and 50°, with normalized speeds of less than half a body length per second (BL/s). HOV is performed at lower pleopod amplitudes and lower beat frequencies when compared to fast-forward swimming (FFW). FFW corresponds to speeds higher than 2 BL/s, independent of body angles. Typical swimming speeds are around 0.25, 4 and 1.6 BL/s, and typical beat frequencies are 3, 6.2 and 3.8 Hz for hovering, fast-forward swimming and upside-down swimming, respectively.
Metachronal rowing aids Antarctic krill to travel long distances, which they do both horizontally and vertically during diel vertical migration. Metachronal rhythms produce larger average propulsion velocities compared to more synchronous rhythms. It has also been shown that krill produce lift to balance the force acting on them as a result of negative buoyancy, allowing them to swim forward while maintaining their position in the water column.
Bio-inspired robotics
Metachronal swimmers have inspired solutions for underwater locomotion in the intermediate Reynolds number regime due to their high maneuverability. Model organisms used to inspired designs include krill, ctenophores (comb jelly), and copepods. Bio-inspired robots can be used to find design solutions for underwater locomotion, as well as give greater insight into their model organism. Robotic models allow for parameter variations that live organisms don't, which gives us the opportunity to explore solutions outside of nature imposed boundaries. A shrimp-inspired metachronal robot can be used to study and understand the flexural asymmetry of shrimp pleopods, and their influence on efficiency and propulsion.
See also
Metachronal rhythm
References
Animal locomotion | Metachronal swimming | [
"Physics",
"Biology"
] | 1,362 | [
"Animal locomotion",
"Physical phenomena",
"Animals",
"Behavior",
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59,202,539 | https://en.wikipedia.org/wiki/%CE%92-Isophorone | β-Isophorone is an organic compound with the formula (CH3)3C6H7O. Classified as a β,γ-unsaturated ketone, it is an isomer of and common impurity in the major industrial intermediate α-isophorone, which is produced from acetone. Like the alpha isomer, beta-isophorone is a colorless liquid.
See also
Phorone
References
Ketones
Ketone solvents
Cyclohexenes | Β-Isophorone | [
"Chemistry"
] | 104 | [
"Ketones",
"Functional groups"
] |
59,202,819 | https://en.wikipedia.org/wiki/METI%20International | METI International, known simply as METI, is a non-profit research organization founded in July 2015 by Douglas Vakoch that creates and transmits interstellar messages to attempt to communicate with extraterrestrial civilizations. It is based in San Francisco, California.
Overview
METI targets nearby stars and researches the nature of the messages to send. On October 16, 17, and 18, 2017, it sent a message consisting of a scientific and mathematical tutorial to the red dwarf Luyten's Star, just over 12 light years from Earth. The message was sent from a radio transmitter at the EISCAT research facility in Tromsø, Norway.
METI's aim is to build an interdisciplinary community to design interstellar messages, within the context of the evolution of intelligence and language. In May 2016, it convened the meeting “The Intelligence Of SETI: Cognition And Communication In Extraterrestrial Intelligence” in Puerto Rico. In May 2018 in Los Angeles, it held “Language in the Cosmos” in conjunction with the International Space Development Conference. to examine the connection between astrobiology and linguistics. On March 22, 2017, it held a workshop in Paris examining the question "What is life?" from an extraterrestrial perspective.
METI also conducts an optical search of extraterrestrial intelligence (SETI). Its optical observatory in Panama looks for laser pulses from advanced civilizations. It has examined anomalous stars like the nearby red dwarf star Ross 128, as well as HD 164595, 94 light years from Earth. None of the searches has yielded evidence of artificial signals.
Criticism
American scientist and science-fiction author David Brin has questioned "whether small groups of zealots should bypass all institutions, peer critique, risk appraisal or public opinion, to shout ‘yoohoo’ into a potentially hazardous cosmos" and so force a fait accompli on humanity.
Numerous other authors and scientists have expressed similar concerns, generally known as the Dark forest hypothesis of ETI, including Stephen Hawking. Of particular interest in science fiction is Cixin Liu's Remembrance of Earth's Past, exploring the theory and some of its implications.
Notable members
Notable members of METI's Board of Directors and Advisory Council include:
Iván Almár, Consultant, Konkoly Observatory of the Hungarian Academy of Sciences, Hungary
Setsuko Aoki, Professor of Policy Management, Keio University, Japan
, Ethics Advisor, Centre national d'études spatiales (CNES), France
Jerome H. Barkow, Professor Emeritus of Social Anthropology, Dalhousie University, Canada
Nelly Ben Hayoun, Designer of Experiences, Nelly Ben Hayoun Studios, UK
Lowry Burgess, Professor of Art, Carnegie Mellon University, USA
Kerri Chandler, Founder of Madhouse Records, USA
Nathaniel C. Comfort, Professor of History of Medicine, Johns Hopkins School of Medicine, USA
Paul Davies, Regents' Professor and Director of the Beyond Center, Arizona State University, USA
Steven J. Dick, Former Chief Historian, National Aeronautics and Space Administration (NASA), USA
David Dunér, Professor of History of Science and Ideas, Lund University, Sweden
George Dvorsky, chair of the board, Institute for Ethics and Emerging Technologies, Canada
José Gabriel Funes, Professor of Philosophy of Nature, Catholic University of Córdoba, Argentina
Ellen Howell, Senior Research Astronomer, Lunar and Planetary Laboratory, University of Arizona, USA
Chris Impey, Associate Dean, College of Science and Distinguished Professor of Astronomy, University of Arizona, USA
Mary Lee Jensvold, Director of the Chimpanzee and Human Communication Institute (CHCI), Central Washington University, USA
James Kasting, Evan Pugh University Professor, Pennsylvania State University, USA
Arik Kershenbaum, Fellow of Girton College at the University of Cambridge, and author of The Zoologist's Guide to the Galaxy, UK
, Researcher and Science Policy Consultant, UNESCO, Argentina
Jeffrey A. Lockwood, Professor of Natural Sciences and Humanities, University of Wyoming, USA
Roger Malina, Arts and Technology Distinguished Chair and Professor of Physics, University of Texas at Dallas, USA
Lori Marino, Founder and executive director, Kimmela Center for Animal Advocacy, Inc., USA
David Messerschmitt, Roger A. Strauch Professor Emeritus of Electrical Engineering & Computer Sciences, University of California, Berkeley, USA
Anson Mount, Actor; known for his portrayal of fictional character, Cullen Bohannon, in the AMC western drama series, Hell on Wheels, and Captain Christopher Pike in season two of Star Trek: Discovery and Star Trek: Strange New Worlds, USA
, Faculty of Life Sciences, University of Vienna, Austria
Alexander Ollongren, Professor Emeritus at Leiden Institute of Advanced Computer Science (LIACS), Leiden University, Netherlands
Serpil Oppermann, Past President, EASCLE (European Association for the Study of Literature, Culture, and the Environment), Turkey
Irene Pepperberg, Research Associate, Harvard University, USA
Ted Peters, Research Professor Emeritus in Systematic Theology and Ethics, Graduate Theological Union (GTU), USA
Stephen G. Post, Director, Center for Medical Humanities, Compassionate Care, and Bioethics, Stony Brook University, USA
Ian Roberts, Professor of Linguistics, University of Cambridge, UK
Holmes Rolston III, University Distinguished Professor and Professor of Philosophy, Emeritus, Colorado State University, USA
Vandana Singh, Professor and Chair of Physics and Earth Sciences, Framingham State University, USA
Susan Stryker, Associate Professor of Gender and Women's Studies and Director of the Institute for LGBT Studies, University of Arizona, USA
Koji Tachibana, Associate Professor of Philosophy, Chiba University, Japan
John Traphagan, Professor of Religious Studies and Anthropology and Mitsubishi Heavy Industries Fellow, University of Texas at Austin, USA
Douglas Vakoch, President of METI, USA
Ariel Waldman, Global Director, Science Hack Day, USA
See also
Active SETI — METI (Messaging to Extra-Terrestrial Intelligence)
Fermi paradox — Lack of evidence that extraterrestrials exist
Zoo hypothesis — Hypothesis that suggests humanity is effectively caged on Earth
References
External links
METI Website
Search for extraterrestrial intelligence
Astrobiology
Space organizations
Science and technology in the San Francisco Bay Area
Research institutes in the San Francisco Bay Area
Science and technology in California
Research institutes in California
Non-profit organizations based in California
Non-profit organizations based in San Francisco
Organizations based in San Francisco
Organizations based in California
Charities based in California | METI International | [
"Astronomy",
"Biology"
] | 1,311 | [
"Origin of life",
"Speculative evolution",
"Astrobiology",
"Astronomy organizations",
"Space organizations",
"Biological hypotheses",
"Astronomical sub-disciplines"
] |
52,944,974 | https://en.wikipedia.org/wiki/Darcy%27s%20law%20for%20multiphase%20flow | Morris Muskat et al. developed the governing equations for multiphase flow (one vector equation for each fluid phase) in porous media as a generalisation of Darcy's equation (or Darcy's law) for water flow in porous media. The porous media are usually sedimentary rocks such as clastic rocks (mostly sandstone) or carbonate rocks.
where a = w, o, g
The present fluid phases are water, oil and gas, and they are represented by the subscript a = w,o,g respectively. The gravitational acceleration with direction is represented as or or . Notice that in petroleum engineering the spatial co-ordinate system is right-hand-oriented with z-axis pointing downward. The physical property that links the flow equations of the three fluid phases, is relative permeability of each fluid phase and pressure. This property of the fluid-rock system (i.e. water-oil-gas-rock system) is mainly a function of the fluid saturations, and it is linked to capillary pressure and the flowing process, implying that it is subject to hysteresis effect.
In 1940 M.C. Leverett pointed out that in order to include capillary pressure effects in the flow equation, the pressure must be phase dependent. The flow equation then becomes
where a = w, o, g
Leverett also pointed out that the capillary pressure shows significant hysteresis effects. This means that the capillary pressure for a drainage process is different from the capillary pressure of an imbibition process with the same fluid phases. Hysteresis does not change the shape of the governing flow equation, but it increases (usually doubles) the number of constitutive equations for properties involved in the hysteresis.
During 1951-1970 commercial computers entered the scene of scientific and engineering calculations and model simulations. Computer simulation of the dynamic behaviour of oil reservoirs soon became a target for the petroleum industry, but the computing power was very weak at that time.
With weak computing power, the reservoir models were correspondingly coarse, but upscaling of the static parameters were fairly simple and partly compensated for the coarseness. The question of upscaling relative permeability curves from the rock curves derived at core plug scale (which is often denoted the micro scale) to the coarse grids cells of the reservoir models (which is often called the macro scale) is much more difficult, and it became an important research field that is still ongoing. But the progress in upscaling was slow, and it was not until 1990-2000 that directional dependency of relative permeability and need for tensor representation was clearly demonstrated, even though at least one capable method was developed already in 1975. One such upscaling case is a slanted reservoir where the water (and gas) will segregate vertically relative to the oil in addition to the horizontal motion. The vertical size of a grid cell is also usually much smaller than the horizontal size of a grid cell, creating small and large flux areas respectively. All this requires different relative permeability curves for the x and z directions. Geological heterogeneities in the reservoirs like laminas or crossbedded permeability structures in the rock, also cause directional relative permeabilities. This tells us that relative permeability should, in the most general case, be represented by a tensor. The flow equations then become
where a = w, o, g
The above-mentioned case reflected downdip water injection (or updip gas injection) or production by pressure depletion. If you inject water updip (or gas downdip) for a period of time, it will give rise to different relative permeability curves in the x+ and x- directions. This is not a hysteresis process in the traditional sense, and it cannot be represented by a traditional tensor. It can be represented by an IF-statement in the software code, and it occurs
in some commercial reservoir simulators. The process (or rather sequence of processes) may be due to a backup plan for field recovery, or the injected fluid may flow to another reservoir rock formation due to an unexpected open part of a fault or a non-sealing cement behind casing of the injection well. The option for relative permeability is seldom used, and we just note that it does not change (the analytical shape of) the governing equation, but increases (usually doubles) the number of constitutive equations for the properties involved.
The above equation is a vector form of the most general equation for fluid flow in porous media, and it gives the reader a good overview of the terms and quantities involved. Before you go ahead and transform the differential equation into difference equations, to be used by the computers, you must write the flow equation in component form. The flow equation in component form (using summation convention) is
where a = w, o, g where = 1,2,3
The Darcy velocity is not the velocity of a fluid particle, but the volumetric flux (frequently represented by the symbol ) of the fluid stream. The fluid velocity in the pores (or short but inaccurately called pore velocity) is related to Darcy velocity by the relation
where a = w, o, g
The volumetric flux is an intensive quantity, so it is not good at describing how much fluid is coming per time. The preferred variable to understand this is the extensive quantity called volumetric flow rate which tells us how much fluid is coming out of (or going into) a given area per time, and it is related to Darcy velocity by the relation
where a = w, o, g
We notice that the volumetric flow rate is a scalar quantity and that the direction is taken care of by the normal vector of the surface (area) and the volumetric flux (Darcy velocity).
In a reservoir model the geometric volume is divided into grid cells, and the area of interest now is the intersectional area between two adjoining cells. If these are true neighboring cells, the area is the common side surface, and if a fault is dividing the two cells, the intersection area is usually less than the full side surface of both adjoining cells. A version of the multiphase flow equation, before it is discretized and used in reservoir simulators, is thus
where a = w, o, g
In expanded (component) form it becomes
where a = w, o, g
The (initial) hydrostatic pressure at a depth (or level) z above (or below) a reference depth z0 is calculated by
where a = w, o, g
When calculations of hydrostatic pressure are executed, one normally does not apply a phase subscript, but switch formula / quantity according to what phase is observed at the actual depth, but we have included the phase subscript here for clarity and consistency. However, when calculations of hydrostatic pressure are executed one may use an acceleration of gravity that varies with depth in order to increase accuracy. If such high accuracy is not needed, the acceleration of gravity is kept constant, and the calculated pressure is called overburden pressure. Such high accuracy is not needed in reservoir simulations so acceleration of gravity is treated as a constant in this discussion. The initial pressure in the reservoir model is calculated using the formula for (initial) overburden pressure which is
where a = w, o, g
In order to simplify the terms within the parenthesis of the flow equation, we can introduce a flow potential called the -potential, pronounced psi-potential, which is defined by
where a = w, o, g
It consists of two terms which are absolute pressure and gravity head. To save computing time the integral can be calculated initially and stored as a table to be used in the computationally cheaper table-lookup. Introduction of the -potential implies that
where a = w, o, g
The psi-potential is also frequently called the "datum pressure", since the function represents the pressure at any point in the reservoir after being transferred to the datum plane / depth z0. In practical engineering work it is very useful to refer pressures measured in wells to a datum level or to map the distribution of datum pressures throughout the reservoir. In this way the direction of fluid movement in the reservoir can be seen at a glance since the datum pressure distribution is equivalent to the potential distribution. Two simple examples will clarify this. A reservoir may consists of several flow units that are separated by tight shale layers. Fluid from one reservoir or flow unit can enter a fault at one depth and exit the fault in another reservoir or flow unit at another depth. Likewise can fluid enter a production well in one flow unit and exit the production well in another flow unit or reservoir.
The multiphase flow equation for porous media now becomes
where a = w, o, g
This multiphase flow equation has traditionally been the starting point for the software programmer when he/she starts transforming the equation from differential equation to difference equation in order to write a program code for a reservoir simulator to be used in the petroleum industry. The unknown dependent variables have traditionally been oil pressure (for oil fields) and volumetric quantities for the fluids involved, but one may rewrite the total set of model equations to be solved for oil pressure and mass or mole quantities for the fluid components involved.
The above equations are written in SI units and we are assuming that all material properties are also defined within the SI units. A result of this is that above versions of the equations do not need any unit conversion constants. The petroleum industry applies a variety of units, of which a least two have some prevalence. If you want to apply units other than SI units, you must establish correct unit conversion constants for the multiphase flow equations.
Conversion of units
The above equations are written in SI units (short SI) suppressing that the unit D (darcy) for the absolute permeability is defined in non-SI units. That is why there are no unit-related constants. The petroleum industry doesn't use the SI units. Instead, they use a special version of SI units that we will call Applied SI units, or they use another set of units called Field units which has its origin from US and UK. Temperature is not included in the equations, so we can use the factor-label method (also called unit-factor method) which says that if we have a variable/parameter with unit H, we multiply this variable/parameter by a conversion constant C and then the variable gets the unit G that we want. This means that we apply the transformation H*C = G, and the non-SI effect of the definition of permeability is included in the conversion factor C for permeability. The transformation H*C = G apply for every spatial dimension so we concentrate on the main terms, neglecting the signs, and then complete the parenthesis with the gravity term. Before we start the conversion, we notice that both the original (single phase) the flow equation of Darcy and the generalized (or extended) multiphase flow equations of Muskat et al. are using reservoir velocity (volume flux), volume rate and densities. The units of these quantities are given a prefix r (or R) in order to distinguish them from their counterparts at standard surface conditions which gets a prefix s (or S). This is especially important when we convert the equations to Field units. The reason for going into details in the seemingly simple topic of unit conversion, is that many people make mistakes when doing unit conversions.
Now we are ready to start the conversion work. First, we take the flux version of the equation and rewrite it as
where a = w, o, g
We want to place the composite conversion factor together with the permeability parameter. Here we note that our equation is written in SI units, and that the group of variables/parameters (hereafter called parameters for short) on the right-hand side constitute a dimensionless group. Now we convert each parameter and collect these conversions into a single conversion constant. Now we note that our list with conversion constants (the C's) goes from applied unit to SI units, and this very common for such conversion lists. We therefore assume that our parameters are entered in applied units and convert them (back) to SI units.
where a = w, o, g
Notice that we have removed relative permeability which is a dimensionless parameter. This composite conversion factor is called Darcy's constant for the flux formulated equation, and it is
Since our parameter group is dimensionless in base SI units, we don't need to include the SI units in the units for our composite conversion factor as you can see in the second table. Next, we take the rate version of the equation and rewrite it as
where a = w, o, g
Now we convert each parameter and collect these conversions into a single conversion constant.
where a = w, o, g
Notice that we have removed relative permeability which is a dimensionless parameter. This composite conversion factor is called Darcy's constant for the flux formulated equation, and it is
The pressure gradient and the gravity term are identical for the flux and the rate equations, and will, therefore, be discussed only once. The task here is to have a gravity term that is consistent with the applied units ("H-units") for the pressure gradient. We must, therefore, place our conversion factor together with the gravity parameters. We write "the parenthesis" in SI units as
where a = w, o, g
and rewrite it as
where a = w, o, g
Now we convert each parameter and collect these conversions into a single conversion constant. First, we note that our equation is written in SI units, and that the group of parameters on the right-hand side constitute a dimensionless group. We, therefore, assume that our parameters are entered in applied units and convert them (back) to SI units.
where a = w, o, g
This gives the composite conversion factor for the consistency-conversion as
Since our parameter group is dimensionless in SI units, we don't need to include the SI units in the units for our composite conversion factor as you can see in the second table.
This is it for the analytical equations, but when the programmer transform the flow equation into a finite difference equation and further into a numerical algorithm, they are eager to minimize the number of computational operations. Here is an example with two constants that can be reduced to one by the fusion
Using industry units, the flux version of the flow equation in vector form becomes
where a = w, o, g
and in component form it becomes
where a = w, o, g where = 1,2,3
Using industry units, the rate version of the flow equation in vector form becomes
where a = w, o, g
and in component form it becomes
where a = w, o, g
Conversion of units is a fairly rare activity, even for technical professionals, but that is also the reason why people forget how to do it correctly.
See also
Petroleum reservoir
Reservoir engineering
Reservoir modeling
Reservoir simulation
Black oil equations
Conversion of units – includes tables of conversion factors
Dimensionless numbers in fluid mechanics
Fermi problem – used to teach dimensional analysis
Rayleigh's method of dimensional analysis
Similitude (model) – an application of dimensional analysis
System of measurement
Units of measurement
List of dimensionless quantities
Orders of magnitude (numbers)
Dimensional analysis
Normalization (statistics) and standardized moment, the analogous concepts in statistics
Buckingham π theorem
References
Fluid dynamics | Darcy's law for multiphase flow | [
"Chemistry",
"Engineering"
] | 3,177 | [
"Piping",
"Chemical engineering",
"Fluid dynamics"
] |
52,945,125 | https://en.wikipedia.org/wiki/First%20and%20second%20fundamental%20theorems%20of%20invariant%20theory | In algebra, the first and second fundamental theorems of invariant theory concern the generators and the relations of the ring of invariants in the ring of polynomial functions for classical groups (roughly the first concerns the generators and the second the relations). The theorems are among the most important results of invariant theory.
Classically the theorems are proved over the complex numbers. But characteristic-free invariant theory extends the theorems to a field of arbitrary characteristic.
First fundamental theorem for
The theorem states that the ring of -invariant polynomial functions on is generated by the functions , where are in and .
Second fundamental theorem for general linear group
Let V, W be finite dimensional vector spaces over the complex numbers. Then the only -invariant prime ideals in are the determinant ideal
generated by the determinants of all the -minors.
Notes
References
Further reading
Ch. II, § 4. of E. Arbarello, M. Cornalba, P.A. Griffiths, and J. Harris, Geometry of algebraic curves. Vol. I, Grundlehren der Mathematischen Wissenschaften, vol. 267, Springer-Verlag, New York, 1985. MR0770932
Hanspeter Kraft and Claudio Procesi, Classical Invariant Theory, a Primer
Invariant theory | First and second fundamental theorems of invariant theory | [
"Physics",
"Mathematics"
] | 263 | [
"Symmetry",
"Algebra stubs",
"Group actions",
"Theorems in algebra",
"Algebra",
"Mathematical problems",
"Mathematical theorems",
"Invariant theory"
] |
52,947,205 | https://en.wikipedia.org/wiki/Conscious%20city | A conscious city is a large built environment that is aware of the needs and activities of its inhabitants and responds to them. Research in conscious cities explores how architecture and urban design can better consider and respond to human needs through data analysis, artificial intelligence, and the application of cognitive sciences in design.
While a smart city focuses on improving efficiency of services, a conscious city applies new technology and behavioral insight into improving an experience and its mental and physiological effects. It is believed that conscious cities could alleviate ailments such as stress, anxiety and boredom by being sensitive to the pervading moods and personalities of people in different parts of the city.
The term was coined by architect Itai Palti and neuroscientist Moshe Bar in their Manifesto for Conscious Cities, published in The Guardian in 2015. Palti went on to establish the conscious cities movement, stating, "The challenge is twofold and symbiotic: to empower and facilitate designers to use [conscious design], and to convince policy-makers, and through them, also market-players that a new set of priorities is essential." The movement launched the Conscious Cities journal in November 2016.
The first conscious cities conference, called "Conscious Cities - Architecture and Neuroscience", was held in 2016.
History
Throughout history, environments were designed to affect people's mood, but the practice was never systematic.
Henri Lefebvre, who pioneered the "right to the city", argued in The Production of Space (1974) that space was a social product, a complex social construction based on values and the social production of meanings, which affected spatial practices and perceptions. Championing Lefebvre's ideas, David Harvey said: "The right to the city is far more than the individual liberty to access urban resources: it is a right to change ourselves by changing the city."
Amos Rapoport examined meaning in the built environment, arguing that a place had not only physical features, but also meanings perceived and decoded by people on the basis of their own expectations, roles, experiences and motivations.
The 21st century brought big data and crowdsourcing, which provide much deeper insights into the relations between cities and their inhabitants.
Characteristics and practice
Architecture, interior design, and urban planning can affect human behaviors and mental processes, causing psychological, biophysical, and cognitive changes in people, often without them noticing. Analyzing how people perceive public spaces with their senses makes it possible to analyze people's place-making practices. For example, visual elements of mystery and complexity may encourage exploration and feelings of pleasure, especially in familiar situations. On the other hand, visual concealments may increase people's fear of crime in public settings. A simple example of a conscious city element is a pair of giant self-inflating artificial flowers in Jerusalem, which bloom to create shade from the sun or cover from rain when sensing approaching pedestrians.
Regarding wayfinding, a conscious city would be one that facilitates memorable mental maps through carefully designing all its elements by focusing on both the physical and the emotional needs of its users. As the average European is getting older, more attention is being paid to making cities "age-friendly," especially in relation to dementia, where conscious-city strategies include "reminiscence promenades," active ground floor frontage, and walkable mixed-use areas.
The mass collection of human data required by conscious cities has raised questions of ethics and privacy. Moreover, a conscious city can react negatively to certain groups by using "hostile architecture," such as sloped public benches to deter homeless people or high-frequency emitters to keep children away.
Research
Initiatives like the Centre for Urban Design and Mental Health, the Urban Realities Laboratory, the Bartlett Centre for Advanced Spatial Analysis, Conscious Design Kalpa or the Center for Advanced Design Research and Evaluation, have been examining the effects of urban planning and policymaking on human psychology and mental health. The Academy of Neuroscience for Architecture promotes and advances the application of neuroscience to human responses to the built environment. The Centric Lab was established in London in 2016 as the first group researching Conscious Design, "that which has an awareness of, and responsibility towards its users."
EEG brain scanning has been researched to emotionally map human reactions to environments in terms of excitement, frustration and engagement, particularly in response to stimuli such as sound, air pollution and light. The architecture firm Perkins and Will has a Human Experience Lab that tests out design concepts and measures human responses through electroencephalography devices, eye tracking, galvanic skin response, motion detectors, and accelerometers. The lab also uses virtual reality headsets and immersive cave automatic virtual environments to test out visual and auditory simulations of planned designs.
CHORA Conscious City, an architecture research facility, started a conscious city project for Gela in 2015 to give the Sicilian town "an avant-garde role in the perspective of a new development model in the Mediterranean, turning it into a portal of transit between two continents, Europe and Africa."
References
Organizational theory
Sustainable urban planning
Urban studies and planning terminology
Information society
Types of cities | Conscious city | [
"Technology"
] | 1,033 | [
"Computing and society",
"Information society"
] |
52,947,580 | https://en.wikipedia.org/wiki/Nauruan%20navigational%20system | The Nauruan navigational system is a way of expressing direction, similar to North, South, East and West, but limitations in the system mean that it is unable to be used outside of Nauru.
The system is constructed using two main points, Ganokoro and Arijeijen. Ganokoro stands for a place in Nauru that was considered a place of sunrise, and Arijeijen was a place of sunset on the island. Arijeijen was close to the place that once hosted a cemetery of the Chinese settlements of the island.
The four main directions are pago, poe, Pawa (Apwewa) and Pwiju (apwijiuw). The word Apuwijiuw was generally translated as "eastwards", and stands for a direction towards Ganokoro, whereas the word Apwewa is translated as "westwards", and stands for a direction towards Arijeijen. The word pago stands for a direction towards the beach (as in the coast of the island) and poe stands for the direction towards the inland of the island, and the words are used in the form rodu apago and roga apoe.
References
Geography of Nauru
Orientation (geometry) | Nauruan navigational system | [
"Physics",
"Mathematics"
] | 254 | [
"Topology",
"Space",
"Geometry",
"Spacetime",
"Orientation (geometry)"
] |
52,948,677 | https://en.wikipedia.org/wiki/Ministry%20of%20Energy%20and%20Minerals%20%28Somaliland%29 | The Ministry of Energy and Minerals () () is one of the governmental bodies of Somaliland. The ministry has the function of developing and implementing policies related to electricity, minerals, petroleum and petroleum products. The current minister is Abdillahi Farah Abdi.
Scope of activities
Energy sector operations
DFID Somaliland has initiated a five-year programme (2014-2019) to improve access to electricity with the introduction of Mini hybrid grids in Somaliland. The programme will be implemented in two phases.
ADRA Somaliland launched a new three-year project (2015-2017) to contribute to poverty alleviation, fragility reduction, and climate change mitigation for rural and peri-urban people in Somaliland.
Somaliland oil blocks
Genel Energy
In August 2012, Genel Energy was awarded an exploration licence for onshore blocks SL-10-B and SL-13 in Somaliland, with a 75% working interest in both. Genel extended its presence in November 2012 with the acquisition of 50% participating interest in the Odwayne Production Sharing Agreement which covers blocks SL-6, SL-7, SL-10A.
Onshore Somaliland is a relatively unexplored region, with few exploration wells drilled. The total size of the blocks is approximately equivalent to the entire Kurdistan Region of Iraq.
Genel took the opportunity because of encouraging indications including onshore oil seeps and existing geological data showing favourable conditions for hydrocarbons to have accumulated in numerous large tilted fault blocks and sub-basins. In addition, the basins of Somaliland were contiguous to Yemen prior to the opening of the Gulf of Aden in the Oligocene-Miocene - similar sedimentary sequences and structural styles are expected in Somaliland.
The ministry are targeting resources of over in blocks SL-10B and SL-13. The Odewayne block has a similar resource potential to this, targeting in order of .
Gravity and aeromag has been acquired and interpreted over the entire 40,000 square km acreage.
DNO ASA
On 8 September 2014, DNO ASA, the Norwegian oil and gas operator, announced that it has been granted a two-year extension of the term of its production sharing agreement for Block SL18 in Somaliland. The first exploration period was set to end on 8 November 2017.
Block SL18, in which DNO has a 50 percent stake as operator, is a frontier exploration block. The partners completed a field survey and environmental assessment studies over the block and was scheduled to initiate a planned seismic acquisition program once the Government of Somaliland has put in place a planned Oil Protection Unit (OPU) to support the international oil companies operating in Somaliland. The OPU was expected to be operational in 2015.
In the interim, security conditions permitting, DNO will resume a development program focused on drilling water wells to provide local communities in the areas covered by Block SL18 with potable water.
Ministers
See also
Politics of Somaliland
Cabinet of Somaliland
References
External links
Official site of the ministry
Government of Somaliland
Energy and Minerals
Energy in Somaliland
Somaliland | Ministry of Energy and Minerals (Somaliland) | [
"Engineering"
] | 625 | [
"Energy organizations",
"Energy ministries"
] |
52,949,290 | https://en.wikipedia.org/wiki/Meizu%20PRO%206%20Plus | The Meizu PRO 6 Plus is a smartphone designed and produced by the Chinese manufacturer Meizu, which runs on Flyme OS, Meizu's modified Android operating system. It is the company's latest model of the flagship PRO series, succeeding the Meizu PRO 6. It was unveiled in November 2016.
The Meizu PRO 6 Plus was released with an updated version of Flyme OS, a modified operating system based on Android Lollipop. It features an alternative, flat design and improved one-handed usability.
Hardware and design
The Meizu PRO 6 features a Samsung Exynos 8890 with an array of eight ARM Cortex CPU cores, an ARM Mali-T880 MP10 GPU for internal storage 64 GB and ARM Mali-T880 MP12 GPU for Internal Storage 128GB, both of them using RAM 4GB high speed LPDDR4 which scores a result of 110.000 points on the AnTuTu benchmark. The rear camera comes with 12 megapixels with ƒ / 2.0 large aperture while the front camera is 5 megapixels with ƒ / 2.0 aperture. Meizu PRO 6 Plus is a dual SIM smartphone that accepts . Connectivity options include Wi-Fi, GPS, Bluetooth, NFC and 4G. Sensors on the phone include Proximity sensor, Accelerometer and Ambient light sensor.
Availability
Meizu PRO 6 Plus is available for sale since November 2016, Meizu selling mobile phone for online and Offline in some countries. Online sales in Asia, only two are India and Israel, Europe is in; France, Italy, Russia, Spain, Ukraine, United Kingdom, South America: Brazil; Oceania: New Zealand. While sales Offline served only at Brunie, Myanmar, Cambodia, New Zealand, and Sri Lanka.
References
Meizu PRO 6 Plus Website
Meizu Store Info
Mobile phones with 4K video recording
Mobile phones introduced in 2016
Meizu smartphones
Discontinued flagship smartphones
Mobile phones with pressure-sensitive touch screen | Meizu PRO 6 Plus | [
"Technology"
] | 408 | [
"Discontinued flagship smartphones",
"Flagship smartphones"
] |
52,950,543 | https://en.wikipedia.org/wiki/Tetramethylthiuram%20sulfide | Tetramethylthiuram sulfide is an organosulfur compound with the formula ((CH3)2NCS)2S. It is a yellow solid that is soluble in organic solvents. It is the parent member of a large class of tetraalkylthiuram sulfides. It is used as an activator in the sulfur vulcanization of natural and butyl rubbers.
Synthesis and structure
It is prepared by desulfuration of tetramethylthiuram disulfides with triphenylphosphine or cyanide:
(Me2NCSS)2 + PPh3 → (Me2NCS)2S + SPPh3
According to X-ray crystallography, the molecule consists of two planar (CH3)2NCS subunits joined by a sulfide. The dihedral angle between the subunits is close to 90°.
References
Organosulfur compounds | Tetramethylthiuram sulfide | [
"Chemistry"
] | 195 | [
"Organic compounds",
"Organosulfur compounds",
"Organic compound stubs",
"Organic chemistry stubs"
] |
52,951,151 | https://en.wikipedia.org/wiki/Scanning%20microscopy | Scanning microscopy may refer to:
Scanning probe microscopy
Atomic force microscopy
Scanning tunneling microscope
Scanning electron microscope
Scanning capacitance microscopy
Near-field scanning optical microscope
Microscopes | Scanning microscopy | [
"Chemistry",
"Technology",
"Engineering"
] | 35 | [
"Microscopes",
"Measuring instruments",
"Microscopy"
] |
52,951,464 | https://en.wikipedia.org/wiki/NGC%201491 | NGC 1491, also known as LBN 704, SH2-206 or the Fossil Footprint Nebula, is an emission type bright nebula located about 9,800 light years away from Earth in the constellation of Perseus. The nebula gets its deep red coloration due to many massive stars (such as BD+50 866) embedded within NGC 1491 producing large amounts of ultraviolet radiation and ionizing the hydrogen gas that makes up the nebula.
Gallery
References
External links
Emission nebulae
Perseus (constellation)
1491
Star-forming regions
Sharpless objects | NGC 1491 | [
"Astronomy"
] | 115 | [
"Perseus (constellation)",
"Nebula stubs",
"Astronomy stubs",
"Constellations"
] |
52,951,921 | https://en.wikipedia.org/wiki/Ignacio%20Rodr%C3%ADguez%20%28programmer%29 | Ignacio Rodríguez (born 1999 in Montevideo) is an Uruguayan programmer, two-time winner of worldwide programming competition Google Code-in (in 2013 and in 2014) and a member of the Sugar Labs educational open-source organization. Rodríguez lives in Canelones.
References
1999 births
Living people
One Laptop per Child
Free software programmers | Ignacio Rodríguez (programmer) | [
"Technology"
] | 66 | [
"Computing stubs",
"Computer specialist stubs"
] |
52,952,373 | https://en.wikipedia.org/wiki/B%20Cygni | The Bayer designation b Cygni is shared by three stars in the constellation Cygnus:
b1 Cygni (V2008 Cygni), an RS CVn variable
b2 Cygni (V1624 Cygni), a Be star
b3 Cygni (V1644 Cygni), a δ Scuti variable
See also
Albireo (β Cygni)
Cygni, b
Cygnus (constellation) | B Cygni | [
"Astronomy"
] | 88 | [
"Cygnus (constellation)",
"Constellations"
] |
52,952,954 | https://en.wikipedia.org/wiki/F%20Cygni | The Bayer designation f Cygni is shared by two stars in the constellation Cygnus:
f1 Cygni, a Be star
f2 Cygni, a K-type supergiant
Cygni, f
Cygnus (constellation) | F Cygni | [
"Astronomy"
] | 49 | [
"Cygnus (constellation)",
"Constellations"
] |
52,953,124 | https://en.wikipedia.org/wiki/Nucleosome%20remodeling%20factor | Nucleosome Remodeling Factor (NURF) is an ATP-dependent chromatin remodeling complex first discovered in Drosophila melanogaster (fruit fly) that catalyzes nucleosome sliding in order to regulate gene transcription. It contains an ISWI ATPase, making it part of the ISWI family of chromatin remodeling complexes. NURF is highly conserved among eukaryotes and is involved in transcriptional regulation of developmental genes.
Discovery
NURF was first purified from the model organism Drosophila melanogaster by Toshio Tsukiyama and Carl Wu in 1995. Tsukiyama and Wu described NURF’s chromatin remodeling activity on the hsp70 promoter. It was later discovered that NURF regulates transcription in this manner for hundreds of genes. A human ortholog of NURF, called hNURF, was isolated in 2003.
Structure
The NURF complex in Drosophila contains four subunits: NURF301, NURF140, NURF55, and NURF38. NURF140 is an ISWI ATPase, distinguishable by its HAND, SANT, and SLIDE domains (SANT-like but with several insertions). The NURF complex in Homo sapiens has three subunits, BPTF, SNF2L, and pRBAP46/48, homologous to NURF301, NURF140, and NURF55, respectively. There is no human homolog for NURF38.
Function
NURF interacts with chromatin by binding to modified histones or interacting with various transcription factors. NURF catalyzes nucleosome sliding in either direction on DNA without any apparent modifications to the histone octamer itself. NURF is essential for the expression of homeotic genes. The ISWI ATPase specifically recognizes intact N-terminal histone tails. In Drosophila, NURF interacts with the transcription factor GAGA to remodel chromatin at the hsp70 promoter, and null mutations in the Nurf301 subunit prevent larval metamorphosis. Other NURF mutants cause the development of melanotic tumors from larval blood cells. In humans, hNURF is involved in neuronal development and has been shown to enhance neurite outgrowth in vitro.
References
Molecular biology
Nuclear organization | Nucleosome remodeling factor | [
"Chemistry",
"Biology"
] | 499 | [
"Biochemistry",
"Nuclear organization",
"Cellular processes",
"Molecular biology"
] |
52,953,323 | https://en.wikipedia.org/wiki/Peritrich%20nuclear%20code | The peritrich nuclear code (translation table 30) is a genetic code used by the nuclear genome of the peritrich ciliates Vorticella and Opisthonecta.
The code (30)
AAs = FFLLSSSSYYEECC*WLLLAPPPPHHQQRRRRIIIMTTTTNNKKSSRRVVVVAAAADDEEGGGG
Starts = --------------*--------------------M----------------------------
Base1 = TTTTTTTTTTTTTTTTCCCCCCCCCCCCCCCCAAAAAAAAAAAAAAAAGGGGGGGGGGGGGGGG
Base2 = TTTTCCCCAAAAGGGGTTTTCCCCAAAAGGGGTTTTCCCCAAAAGGGGTTTTCCCCAAAAGGGG
Base3 = TCAGTCAGTCAGTCAGTCAGTCAGTCAGTCAGTCAGTCAGTCAGTCAGTCAGTCAGTCAGTCAG
Bases: adenine (A), cytosine (C), guanine (G) and thymine (T) or uracil (U).
Amino acids: Alanine (Ala, A), Arginine (Arg, R), Asparagine (Asn, N), Aspartic acid (Asp, D), Cysteine (Cys, C), Glutamic acid (Glu, E), Glutamine (Gln, Q), Glycine (Gly, G), Histidine (His, H), Isoleucine (Ile, I), Leucine (Leu, L), Lysine (Lys, K), Methionine (Met, M), Phenylalanine (Phe, F), Proline (Pro, P), Serine (Ser, S), Threonine (Thr, T), Tryptophan (Trp, W), Tyrosine (Tyr, Y), and Valine (Val, V).
Differences from the standard code
See also
List of all genetic codes: translation tables 1 to 16, and 21 to 31.
The genetic codes database.
References
Molecular genetics
Gene expression
Protein biosynthesis | Peritrich nuclear code | [
"Chemistry",
"Biology"
] | 532 | [
"Protein biosynthesis",
"Gene expression",
"Molecular genetics",
"Biosynthesis",
"Cellular processes",
"Molecular biology",
"Biochemistry"
] |
52,953,373 | https://en.wikipedia.org/wiki/Hardware%20backdoor | A hardware backdoor is a backdoor implemented within the physical components of a computer system, also known as its hardware. They can be created by introducing malicious code to a component's firmware, or even during the manufacturing process of a integrated circuit, known as a hardware trojan. Often, they are used to undermine security in smartcards and cryptoprocessors, unless investment is made in anti-backdoor design methods. They have also been considered for car hacking.
Background
The existence of hardware backdoors poses significant security risks for several reasons. They are difficult to detect and are impossible to remove using conventional methods like antivirus software. They can also bypass other security measures, such as disk encryption. Hardware trojans can be introduced during manufacturing where the end-user lacks control over the production chain.
History
In 2008, the FBI reported the discovery of approximately 3,500 counterfeit Cisco network components in the United States, some of which were introduced in military and government infrastructure.
A few years later, in 2011, Jonathan Brossard presented "Rakshasa", a proof-of-concept hardware backdoor. This backdoor could be installed by an individual with physical access to the hardware. It utilized coreboot to re-flash the BIOS with a SeaBIOS and iPXE-based bootkit composed of legitimate, open-source tools, allowing malware to be fetched from the internet during the boot process.
The following year, in 2012, Sergei Skorobogatov and Christopher Woods from the University of Cambridge Computer Laboratory reported the discovery of a backdoor in a military-grade FPGA device, which could be exploited to access and modify sensitive information. It has been said that this was proven to be a software problem and not a deliberate attempt at sabotage. This still brought to attention that equipment manufacturers should ensure that microchips operate as intended. Later that year, two mobile phones developed by the Chinese company ZTE were found to carry a root access backdoor. According to security researcher Dmitri Alperovitch, the exploit used a hard-coded password in its software.
Starting in 2012, the United States stated that Huawei might have backdoors present in their products.
In 2013, researchers at the University of Massachusetts devised a method of breaking a CPU's internal cryptographic mechanisms by introducing specific impurities into the crystalline structure of transistors to change Intel's random-number generator.
Documents revealed from 2013 onwards during the surveillance disclosures initiated by Edward Snowden showed that the Tailored Access Operations (TAO) unit and other NSA employees intercepted servers, routers, and other network gear being shipped to organizations targeted for surveillance to install covert implant firmware onto them before delivery. These tools include custom BIOS exploits that survive the reinstallation of operating systems and USB cables with spy hardware and radio transceiver packed inside.
In June 2016 it was reported that University of Michigan Department of Electrical Engineering and Computer Science had built a hardware backdoor that leveraged "analog circuits to create a hardware attack" so that after the capacitors store up enough electricity to be fully charged, it would be switched on, to give an attacker complete access to whatever system or device − such as a PC − that contains the backdoored chip. In the study that won the "best paper" award at the IEEE Symposium on Privacy and Security they also note that microscopic hardware backdoor wouldn't be caught by practically any modern method of hardware security analysis, and could be planted by a single employee of a chip factory.
In September 2016 Skorobogatov showed how he had removed a NAND chip from an iPhone 5C - the main memory storage system used on many Apple devices - and cloned it so that he can try out more incorrect combinations than allowed by the attempt-counter.
In October 2018 Bloomberg reported that an attack by Chinese spies reached almost 30 U.S. companies, including Amazon and Apple, by compromising America's technology supply chain.
Countermeasures
Skorobogatov has developed a technique capable of detecting malicious insertions into chips.
New York University Tandon School of Engineering researchers have developed a way to corroborate a chip's operation using verifiable computing whereby "manufactured for sale" chips contain an embedded verification module that proves the chip's calculations are correct and an associated external module validates the embedded verification module. Another technique developed by researchers at University College London (UCL) relies on distributing trust between multiple identical chips from disjoint supply chains. Assuming that at least one of those chips remains honest the security of the device is preserved.
Researchers at the University of Southern California Ming Hsieh Department of Electrical and Computer Engineering and the Photonic Science Division at the Paul Scherrer Institute have developed a new technique called Ptychographic X-ray laminography. This technique is the only current method that allows for verification of the chips blueprint and design without destroying or cutting the chip. It also does so in significantly less time than other current methods. Anthony F. J. Levi Professor of electrical and computer engineering at University of Southern California explains “It’s the only approach to non-destructive reverse engineering of electronic chips—[and] not just reverse engineering but assurance that chips are manufactured according to design. You can identify the foundry, aspects of the design, who did the design. It’s like a fingerprint.” This method currently is able to scan chips in 3D and zoom in on sections and can accommodate chips up to 12 millimeters by 12 millimeters easily accommodating an Apple A12 chip but not yet able to scan a full Nvidia Volta GPU. "Future versions of the laminography technique could reach a resolution of just 2 nanometers or reduce the time for a low-resolution inspection of that 300-by-300-micrometer segment to less than an hour, the researchers say."
See also
Clipper chip
FBI–Apple encryption dispute
Hardware security
Hardware security bug
Hardware Trojan
Zombie Zero
Open hardware
Code signing
Intel Management Engine
AMD Platform Security Processor
References
Further reading
Espionage techniques
Computer hardware
Surveillance
Cryptographic attacks
Cyberwarfare
Malware | Hardware backdoor | [
"Technology",
"Engineering"
] | 1,253 | [
"Malware",
"Computer engineering",
"Cryptographic attacks",
"Computer hardware",
"Computer systems",
"Computer science",
"Computer security exploits",
"Computers"
] |
52,954,530 | https://en.wikipedia.org/wiki/Intermediate-Current%20Stability%20Experiment | The Intermediate-Current Stability Experiment, or ICSE, was a magnetic fusion energy reactor designed by the UKAEA ("Harwell") design team. It was intended to be the follow-on design to the ZETA, incorporating a high-speed current pulse system that was expected to improve the stability of the plasma and allow fusion reactions to take place. Construction began in 1959, starting with its building known as "D-1", but Harwell's new director expressed concerns about some of the theoretical assumptions being made about the design, the project was canceled in August 1960. Parts that were already built were scavenged by other teams.
History
ZETA and ZETA II
The Harwell fusion team completed construction of the ZETA reactor in August 1957. This was the world's first truly large-scale fusion device, both in size and in terms of the power fed into the plasma. After the machine proved stable, the teams began introducing deuterium fuel into the mix, and immediately noticed neutrons being released. Neutrons are the most easily seen results of fusion reactions, but the team was highly cautious due to several warnings of non-nuclear neutrons from teams in the US and USSR. A series of diagnostic "shots" through September and October were used to characterize the plasma. Spectrographic analysis of the plasma taken through small windows in the reactor's torus suggested the plasma was at a temperature of somewhere between 1 and 5 million degrees, which then-current theory suggested would cause a fusion rate within a factor of two of what was being measured. It appeared the neutrons were indeed from fusion events.
The apparent success led to plans for a much larger follow-on reactor known as ZETA II. The goal of ZETA had been to generate low levels of fusion reactions, the goal for ZETA II was to produce so many reactions that the energy they released would be greater than the energy fed into the system, a condition known as "break even" or Q=1. To reach these energy levels, the reactor would have to be much larger and more powerful than the original ZETA, and it would be difficult to find room for it at Harwell. The need for more room led to John Cockcroft suggesting it be moved to the new Winfrith location, arguing that it was a prototype for a commercial machine, like the other reactors being built there. This was highly contentious; many members of the fusion team at Harwell were uninterested in moving and argued that losing the theoretical support at Harwell would be an enormous problem. The matter came to a head in a mid-January 1958 meeting which did not go smoothly.
But any anger over the issue of choosing a site for ZETA II was completely overshadowed by the impending announcement of the ZETA results. This took place on Saturday 22 January 1958, with careful wording to note that the source of the neutrons had not yet been verified and it was not sure that they were from fusion. However, the assembled press reporters were not happy with these statements and continued to press Cockcroft on the issue. He eventually stated that in his own opinion they were 90% likely to be due to fusion. The reporters took this as a statement of fact, and the Sunday papers all claimed that fusion had been successfully achieved. A press release from the UKAEA to the contrary was largely ignored, and concerns expressed by researchers from other countries were dismissed as jingoism.
However, further research on ZETA demonstrated the neutrons were indeed not from fusion. Cockcroft was forced to publish a humiliating retraction in May, and the ZETA II plans were thrown into disarray. By this time the design for ZETA II had grown considerably, it now featured a torus of in diameter, the toroidal magnets that provided stability increased in size 30 times, and the current pulse required to operate it demanded an enormous power supply, using details developed and patented at Harwell.
References
Fusion power | Intermediate-Current Stability Experiment | [
"Physics",
"Chemistry"
] | 801 | [
"Nuclear fusion",
"Fusion power",
"Plasma physics"
] |
64,185,391 | https://en.wikipedia.org/wiki/Alaninol | Alaninol is the organic compound with the formula CH3CH(NH2)CH2OH. A colorless solid, the compound is classified as an amino alcohol. It can be generated by converting the carboxylic group of alanine to an alcohol with a strong reducing agent such as lithium aluminium hydride. The compound is chiral, and as is normal for chiral compounds, the physical properties of the racemate differ somewhat from those of the enantiomers. It is a precursor to numerous chiral ligands used in asymmetric catalysis. The compound is an example of a 1,2-ethanolamine.
References
Amino alcohols | Alaninol | [
"Chemistry"
] | 138 | [
"Organic compounds",
"Amino alcohols"
] |
64,186,951 | https://en.wikipedia.org/wiki/18-Methyltestosterone | 18-Methyltestosterone (18-MT) is an androgen/anabolic steroid (AAS) which was never marketed. Along with 19-nortestosterone (nandrolone) and 17α-ethynyltestosterone (ethisterone), it is a parent structure of a number of progestogens and AAS. These include the progestogens levonorgestrel (17α-ethynyl-18-methyl-19-nortestosterone) and its derivatives (e.g., desogestrel, gestodene, norgestimate, gestrinone) as well as AAS such as norboletone (17α-ethyl-18-methyl-19-nortestosterone) and tetrahydrogestrinone (THG; δ9,11-17α-ethyl-18-methyl-19-nortestosterone).
See also
List of androgens/anabolic steroids
References
Abandoned drugs
Anabolic–androgenic steroids
Androstanes
Enones
Tertiary alcohols | 18-Methyltestosterone | [
"Chemistry"
] | 237 | [
"Drug safety",
"Abandoned drugs"
] |
64,187,070 | https://en.wikipedia.org/wiki/Cryptic%20mimicry%20in%20plants | Cryptic mimicry is observed in animals as well as plants. In animals, this may involve nocturnality, camouflage, subterranean lifestyle, and mimicry. Generally, plant herbivores are visually oriented. So a mimicking plant should strongly resemble its host; this can be done through visual and/or textural change. Previous criteria for mimicry include similarity of leaf dimensions, leaf presentation, and intermodal distances between the host and mimicking plant.
Australian mistletoe and Boquila trifoliolata are well known examples of this mimicry. Researchers hypothesize that crypsis is used to reduce the likelihood of vertebrate herbivory and thus improve the survivability and fitness of the mimicking plant.
Mistletoe
Mistletoe, or Viscum album, is an obligate hemi-parasite meaning it attaches to its host tree and extracts water and nutrients. Australia is home to over 90 species of mistletoe, with 70 being native. Studies evaluating the role of crypsis on herbivory measure leaf quality, such as nitrogen and protein levels, water content, etc. Ehleringer et al. examined nitrogen levels, as an indicator of protein status, of mistletoe and their host (Acacia, Cassia, Casuarina, Ceriops, and Eucalyptus) to determine if mimicry reduced herbivory in the plant.
One hypothesis tested was mistletoe that show mimicry would have higher nitrogen levels and have a selective advantage through reduced herbivory. A second hypothesis tested was mistletoe that do not demonstrate mimicry would have lower nitrogen levels and appear at a lower nutritional status and have reduced herbivory as a result. Seemingly, the researchers thought that the act of mimicry would increase nitrogen levels and depending on nutritional status and detectability, herbivory would be affected. Previous studies have shown that animals may prefer different food resources depending on their water content, vitamins, carbohydrates and energy needs, and appearance might play into an animal’s perception and preference.
Record of Kjeldahl nitrogen in the leaves was taken to measure reduced nitrogen levels in the mistletoe, which would affect amino acids, proteins, etc, and possible preference of herbivores. From their results, Ehleringer et al. found that the majority (17 of 22) of mimetic mistletoe had nitrogen levels that were either equal to or greater than their hosts. However, mistletoe that mimicked the Eucalyptus species had nitrogen levels lower or equal to their hosts. Eucalyptus typically has high oil content which is thought to be an anti-herbivory mechanism. One thought might be that in additional effort to avoid herbivory, having lower nitrogen levels and therefore lower nutrition, mistletoe would be less favorable to herbivores than the host Eucalyptus. Of the non-mimetic mistletoe, 15 of 26 had significantly lower nitrogen levels than their hosts. The lowered nitrogen would reflect lower protein levels and potentially lower nutrition to potential herbivores.
Ehleringer et al. can only make predictions about the mechanism of mimicry and herbivory rates as no herbivory was actually studied or measured in mistletoe and host plants.
Boquila
In their research, Gianoli and Carrasco-Urra demonstrate the effect cryptic mimicry can have on the herbivory of the Boquila trifoliolata. Native to the temperate rainforest of South America, Boquila is a climbing vine. Compared to other cryptic plants, Boquila is unique in its ability to mimic several hosts despite no parasitic relationships. Like others, Gianoli and Carrasco-Urra set out to prove that Boquila mimicry results in protection against herbivory.
Boquila leaf traits (such as size, shape, color, orientation) were compared with its native host tree species to try to explain such wide morphological changes. Out of 11 traits, there was significant phenotypic association between 9 traits of the Boquila and host leaves. Leaves of unsupported vines growing on the ground did not differ from those of vines growing on leafless stems or trees; showing that when there is no leaf to mimic, climbing plants do not differ from unsupported plants.
It was measured that herbivory remained equal between climbing vines and unsupported hosts. Herbivory was significantly higher in vines growing unsupported than in vines climbing on trees. Lastly, herbivory on vines climbing leafless hosts was higher than in unsupported vines. These results suggest that the act of climbing is not enough to avoid herbivory, but additional mimicry of supported leaves may reduce herbivory rates.
An interesting note about the Boquila is that leaf mimicry can occur even when there is no contact between the vine and its host. High phenotypic plasticity allows the Boquila to mimic several hosts simultaneously but it does not explain the mechanism behind its mimicry.
Mechanism
Currently, there is no known explanation for leaf mimicry. In the Boquila, because mimicry is observed despite lack of physical contact between the vine and its host, hypotheses of plant volatile and horizontal gene transfer have been mentioned.
Volatile organic compounds have been shown to elicit defense responses in inter-plant and plant-plant situations. When attacked by herbivores, plants release a blend of volatiles that can initiate response in systemic leaves as well as neighboring plants. It has been observed that volatile signals increased the expression of genes related to plant defense and resulted in change to the transcriptome. In mimicry, response to volatiles could be gene edits in the plant, which could change the expression of certain genes and result in phenotypic change.
In the Venus fly trap, stimulation of mechanoreceptors and calcium release trigger jasmonic acid synthesis. Proteins and enzymes have been shown to be involved in transport and perception of volatiles. They could also play a role in the conversion of a volatile signal to a chemical product response e.g. salicylic acid and methyl salicylate. With the mistletoe, a possible line of study could be measuring nitrogen level change after mimicry to see if nitrogen is involved in perception of volatiles or if it changes as a result from perception.
Horizontal gene transfer involves movement of genetic material without being passed down to offspring. It plays an important role in the evolution of many organisms. It is hypothesized that transfer is conducted through a vector or is a result of plant-plant parasitism.
Little is known about how this method could be involved in plant mimicry but it is mentioned by Gianoli and Carrasco-Urra as an explanation that Boquila mimicry is observed depending on which host the plant is nearest to, despite previous contact. Possible transfer within close distances would explain varying amounts of mimicry seen in Boquila and its hosts.
Plant-plant interactions
Not much is known about the underlying mechanisms of how the mimicking plants and their hosts are able to communicate, or if they do at all. Kin recognition would be an area to further study as it might reveal more about volatile communication between plants. Heil and Karban note that the use of volatiles can be costly to the emitter which poses the question of competition and cost between the host and mimicker. If the host were to somehow recognize the mimicker as kin, it would offer potential reasoning for the exchange between the two. Similar to a study from Crepy et al. in which they noticed plants that recognized kin shifted their leaf position to benefit kin plants growing nearby. Close phenotypic association was observed and could be explored further. Others have discussed that instead of communication, Boquila and other plants eavesdrop on their hosts.
It might be that instead of the mimicking plant solely benefitting, the host plant could also experience reduced herbivory as potential herbivores might mistake the Boquila for the host. This would suggest that the relationship between mimicker and host is not just beneficial to the mimicker. Further research into the plant-plant interactions would need to be done in order to answer these questions.
References
Mimicry | Cryptic mimicry in plants | [
"Biology"
] | 1,683 | [
"Mimicry",
"Biological defense mechanisms"
] |
64,187,174 | https://en.wikipedia.org/wiki/Hydraulic%20signaling%20in%20plants | Hydraulic signals in plants are detected as changes in the organism's water potential that are caused by environmental stress like drought or wounding. The cohesion and tension properties of water allow for these water potential changes to be transmitted throughout the plant.
Plants respond to external stimuli through thigmomorphogenesis. For example, bending a shoot can cause arrestment of growth on another area of the plant. These types of nonlocal responses can be induced by long distance signaling. Long distance communication in plants must satisfy two things: First, signaling must occur rapidly to an apical area of the plant; Second, the signal must be perceived at the apical site and be converted to a physiological or thigmorphogenetic response. One form of long distance signaling is through hydraulic pulses from the roots to the shoots of a plant. Tree branches and stems contain microchannels that make up the xylem network and serve to carry water longitudinally. Stimuli like wounding can cause tension and compression of plant tissues, which pinches the cross section of the shoot. Hydraulic signaling begins with a local response like water expulsion, creating a suction in the vascular system. The compression of the cross section will then lead to a general increase of hydraulic pressure in the channels of the shoot. This extensive change in hydraulic pressure will lead to activation of hydraulic sensors.
Water potential
The driving force of the movement of water is the water potential gradient. The water potential gradient is defined by comparing the potential energy of water to pure water at standard conditions. This water potential gradient must be maintained from the soil through the plant and into the air via transpiration. In the xylem, water is transported throughout the plant following increasing water potential differences. These differences are determined by soil water availability and vapor pressure deficit. If this gradient is flipped the translocation of water will occur in the opposite direction. The water potential is the combination of the pressure potential, the osmotic potential and the gravitational contribution. The translocation of water can be restricted by resistances like stomatal aperture, xylem structure related resistance to flow etc.
Long-distance signaling
In order for plants to respond and adapt to external stimuli, long distance signaling is required. In general terms, long distance signaling is defined as the ability to have a widespread response when just one distinct area is stimulated. In plants, water uptake must be tightly controlled, so long-distance signaling by hydraulic cues coordinate plants above and below-ground organs. The daily physiological behavior of plants is tightly controlled by hydraulic signals. Gradients of water potentials are transferred across the plant through hydraulic signals. If the hydraulic signal originated in the root, it will result in local water potential changes, and consequently turgor changes. The water potential changes can be due to dry soil, water loss via transpiration or physically wounding the plant. These local water potential changes are then transmitted quickly over long-distances as hydraulic signals. Hydraulic signaling is fast and effective because of the cohesion and tension properties of water. Hydraulic signals can be propagated downward or upward, relaying water potential gradients throughout the entire plant.
Hydraulic signals can be sensed in a few ways all relating to how an increase in water potential affects the plants. Because water leaves the cell, there is a reduction in the pressure potential and an increase in solute concentration. This is one way the hydraulic signal can be sensed, through sensing the osmotic environment. Increase in water potential also causes mechanical forces on the cell wall and plasma membrane of the cell. This is the second way to sense hydraulic signaling, by sensing the changes in the mechanical forces on the cell wall.
Experimental methods for studying hydraulic signaling
Linear beam theory
Biomimetic systems can be used to mimic the microchannels inside branches. These synthetic plant systems are made from polydimethylsiloxane (PDMS) and 3D molded like branches and filled with a silicone oil (with viscosity 1 Pa*s). Channels are connected by a differential pressure sensor. The initial branch is straight and the internal water pressure is equal to the atmospheric pressure |Pref-P0=0|. Hydraulic pulses are then induced by automated linear motor deplacement, creating a bend in the synthetic branches which results in a rise in overpressure (Pref), reaching a value of |Pref-P0| or deltaP. Returning back to the initial state of the branch will bring the value of deltaP back to 0. The observation is that overpressure increases quadratically with bending strain. This response changes with variation in beam rigidity.
Nonlinear poroelastic coupling
In a nonlinear poroelastic system, elastic tubes begin straight. When bent, elastic strain increases proportionally with the distance from the initial position. This induces a bending elastic energy per unit of volume that is quadratically related to the transverse radius. The system will lower this elastic energy by squeezing its cross section. This transverse compression leads to a decrease in the channel volume creating a global increase in pressure. Therefore, the mechanism of generating hydraulic pressure is due to the coupling of bending and the transverse deformation of the elastic beam.
Hydraulic signaling in natural branches
Louf et al. has conducted research on hydraulic signaling in 3 species: P. sylvestris, Quercus ilex, and P.alba. Their findings can be summarized by these points: Bending of a branch leads to an increase in xylem water pressure. The magnitude of response depends on the species of plant and the environmental conditions. Hydraulic pulses were found to be greater in trees grown outside with stiffer properties, also proving that elasticity plays a role in hydraulic pulses.
Mechanism
The overall pathway of hydraulic signaling in plants is similar to that of a sensory pathway, starting with basic perception of the signal by a sensor, which then converts the hydraulic signal into a chemical signal: abscisic acid or ABA. This conversion to a chemical signal leads to the control of different physiological responses in the plant since ABA is a plant hormone known to mediate many plant developmental processes including organ size, stomatal closure, and dormancy in the plants’ seeds and buds.
Hydraulic signals are primarily detected as decreases in water potential, usually caused by increases in solute concentration or drought. This decrease in water potential is systemic and transferred throughout the plant vascular network via the xylem. Water follows down the water potential gradient from parenchyma cells into the xylem, ultimately leading to a decrease in pressure potential and osmotic potential in the adjacent cells to the xylem. The hydraulic sensor, which is yet to be known, resides on the inner membrane of the parenchyma cells and detects the decreases in pressure and solute potential through an unknown mechanism. After detection, the unidentified sensor initiates a signal cascade, leading to a calcium transient and subsequent reactive oxygen species (ROS) formation. These ROS are proposed to go on to target ABA biosynthesis enzymes, leading to synthesis of ABA in the parenchyma and later export to regions of the plant requiring the appropriate responses. In an example, ABA response to a hydraulic signal from the roots- a decrease in water potential- is thought to reach the guard cells to stimulate stomatal closure. Despite an unidentified hydraulic sensor(s) and the mechanism of which this sensor detects decreases in pressure and solute potential in the parenchyma, this primary site of ABA biosynthesis is thought to additionally participate as the main location of hydraulic signal perception, vital to mediation of water potential in the plant.
ABA
Abscisic acid (ABA) is a phytohormone that plays a significant role in the plants’ response to drought conditions. During drought, its biosynthesis is triggered and controls many physiological responses. ABA triggers root growth at low concentrations and closes stomata to prevent water loss from transpiration. ABA is essential for hydraulic signals because of its response to local water potential changes. ABA is also known to increase hydraulic conductance by increasing aquaporin expression.
Hydraulic sensors
Although sensor(s) for hydraulic signals are unknown and still being investigated, several sensor candidates have been suggested. One candidate for a hydraulic signal sensor has been MCA1, a plasma membrane protein correlated with mechanosensing via calcium-mediated influx in Arabidopsis thaliana. Research has found that MCA1 increased cytoplasmic calcium concentrations in response to a mechanosensory input: plasma membrane distortion in Arabidopsis.
Another sensor candidate proposed are PERKs, members of the proline-rich receptor kinase family in Arabidopsis as well. PERK4 specifically plays a crucial role in abscisic acid (ABA) signalling and response and has shown to be an ABA- and calcium-activated protein kinase. Both MCA1 and PERK4 appear to correlate with cytoplasmic calcium gradients and an early response to hydraulic signals since calcium is known to be involved in plants’ early responses to mechanosensation.
Despite research on these sensor candidates, both ABA and calcium gradient participation in early events of hydraulic signaling have made it particularly difficult to distinguish the order of which each part plays in the hydraulic signaling pathway.
MCA1
MCA1 has been identified as a candidate for a Ca2+ permeable mechanosensitive channel in Arabidopsis thaliana. Overexpression of plasma membrane protein MCA1 causes an increase in calcium uptake from the roots, which then causes an increase in free calcium in the cytoplasm. MCA1 expression in yeast mutants lacking a high affinity calcium influx system will also increase calcium uptake.
MCA2
MCA2 is a paralog of MCA1 that was identified in Arabidopsis thaliana. Protein sequencing technology reveals that the two genes are 72.7% identical and 89.4% similar in amino acid sequence, making MCA2 a reasonable gene to use in studies to determine the function of MCA1 in calcium uptake. Reverse transcription PCR analysis indicates that MCA2 is expressed in the plasma membrane in leaves, flowers, roots, and stems. Knockout of the MCA2 gene causes a decrease in calcium uptake in the roots, relative to the wildtype, suggesting that the MCA2 gene is involved in calcium uptake.
Using GUS staining, researchers were able to find expressions of MCA1 and MCA2 in the pericycle and endodermis of the root in Arabidopsis. No expression was identified in the cortex or epidermis. Rise in cytosolic calcium levels in the pericycle and endodermis under drought conditions suggest that these cells play a role in calcium signaling. The spatial expression of MCA1 and MCA2 and the changes in calcium concentration in the pericycle and endodermis suggests that both MCA1 and MCA2 play a role in symplastic calcium transport and signaling.
PERK4
Proline-rich extensin-like receptor kinases 4 (PERK4) is a gene expressed in the roots and flowers in Arabidopsis thaliana that localizes in the plasma membrane and plays a role in ABA signaling. Using protein motif analysis, a membrane localization signal, a transmembrane domain, and an intracellular kinase domain were identified in PERK4. To study the role of PERK4 and ABA, mutants were made by inserting T-DNA. PERK4 mutants showed a decrease in ABA sensitivity which affects seedling germination and root tip growth. Mutating PERK4 causes cytosolic free calcium levels to decrease in roots relevant to the wild type. The function of PERK4 has been proposed in early stage ABA signalling to inhibit root elongation by disturbing cytoplasmic calcium gradients.
Ongoing research
Arabidopsis thaliana has been a primary model system in the search for the hydraulic sensor however, has not yet produced a certain answer. Screens for plant mutants affected in hydraulic signaling have been necessary yet, none have been reported so far. Some plant mutants have been distinguished by using the Arabidopsis line pAtH-B6::LUC with lesions upstream of ABA action. Recent years prior to 2013 have shown more hydraulic sensor candidates such as osmosensors and turgor sensors however, research is ongoing as to the specific roles they may play in hydraulic signaling in plants.
References
Plant physiology | Hydraulic signaling in plants | [
"Biology"
] | 2,514 | [
"Plant physiology",
"Plants"
] |
64,189,063 | https://en.wikipedia.org/wiki/Minimum%20evolution | Minimum evolution is a distance method employed in phylogenetics modeling. It shares with maximum parsimony the aspect of searching for the phylogeny that has the shortest total sum of branch lengths.
The theoretical foundations of the minimum evolution (ME) criterion lay in the seminal works of both Kidd and Sgaramella-Zonta (1971) and Rzhetsky and Nei (1993). In these frameworks, the molecular sequences from taxa are replaced by a set of measures of their dissimilarity (i.e., the so-called "evolutionary distances") and a fundamental result states that if such distances were unbiased estimates of the true evolutionary distances from taxa (i.e., the distances that one would obtain if all the molecular data from taxa were available), then the true phylogeny of taxa would have an expected length shorter than any other possible phylogeny T compatible with those distances.
Relationships with and comparison with other methods
Maximum parsimony
It is worth noting here a subtle difference between the maximum-parsimony criterion and the ME criterion: while maximum-parsimony is based on an abductive heuristic, i.e., the plausibility of the simplest evolutionary hypothesis of taxa with respect to the more complex ones, the ME criterion is based on Kidd and Sgaramella-Zonta's conjectures that were proven true 22 years later by Rzhetsky and Nei. These mathematical results set the ME criterion free from the Occam's razor principle and confer it a solid theoretical and quantitative basis.
Maximum-parsimony criterion, which uses Hamming distance branch lengths, was shown to be statistically inconsistent in 1978. This led to an interest in statistically consistent alternatives such as ME.
Neighbor joining
Neighbor joining may be viewed as a greedy heuristic for the balanced minimum evolution (BME) criterion. Saito and Nei's 1987 NJ algorithm far predates the BME criterion of 2000. For two decades, researchers used NJ without a firm theoretical basis for why it works.
Statistical consistency
The ME criterion is known to be statistically consistent whenever the branch lengths are estimated via the Ordinary Least-Squares (OLS) or via linear programming.
However, as observed in Rzhetsky & Nei's article, the phylogeny having the minimum length under the OLS branch length estimation model may be characterized, in some circumstance, by negative branch lengths, which unfortunately are empty of biological meaning.
To solve this drawback, Pauplin proposed to replace OLS with a new particular branch length estimation model, known as balanced basic evolution (BME). Richard Desper and Olivier Gascuel showed that the BME branch length estimation model ensures the general statistical consistency of the minimum length phylogeny as well as the non-negativity of its branch lengths, whenever the estimated evolutionary distances from taxa satisfy the triangle inequality.
Le Sy Vinh and Arndt von Haeseler have shown, by means of massive and systematic simulation experiments, that the accuracy of the ME criterion under the BME branch length estimation model is by far the highest in distance methods and not inferior to those of alternative criteria based e.g., on Maximum Likelihood or Bayesian Inference. Moreover, as shown by Daniele Catanzaro, Martin Frohn and Raffaele Pesenti, the minimum length phylogeny under the BME branch length estimation model can be interpreted as the (Pareto optimal) consensus tree between concurrent minimum entropy processes encoded by a forest of n phylogenies rooted on the n analyzed taxa. This particular information theory-based interpretation is conjectured to be shared by all distance methods in phylogenetics.
Algorithmic aspects
The "minimum evolution problem" (MEP), in which a minimum-summed-length phylogeny is derived from a set of sequences under the ME criterion, is said to be NP-hard. The "balanced minimum evolution problem" (BMEP), which uses the newer BME criterion, is APX-hard.
A number of exact algorithms solving BMEP have been described. The best known exact algorithm remains impractical for more than a dozen taxa, even with multiprocessing. There is only one approximation algorithm with proven error bounds, published in 2012.
In practical use, BMEP is overwhelmingly implemented by heuristic search. The basic, aforementioned neighbor-joining algorithm implements a greedy version of BMEP. FastME, the "state-of-the-art", starts with a rough tree then improves it using a set of topological moves such as Nearest Neighbor Interchanges (NNI). Compared to NJ, it is about as fast and more accurate. Metaheuristics have also been used.
See also
Least squares inference in phylogeny
Occam's razor
References
Further reading
Phylogenetics
Computational phylogenetics | Minimum evolution | [
"Biology"
] | 1,013 | [
"Genetics techniques",
"Computational phylogenetics",
"Taxonomy (biology)",
"Bioinformatics",
"Phylogenetics"
] |
64,189,451 | https://en.wikipedia.org/wiki/Gina%20R.%20Poe | Gina R. Poe is an American neuroscientist specializing in the study of sleep and its effect on memory and learning. Her findings have shown that the absence of noradrenaline and low levels of serotonin during sleep spindles allow the brain to form new memories during REM, as well as restructure old memory circuits to allow for more learning during later waking periods. She currently works as a professor at the University of California, Los Angeles (UCLA).
Early life and education
Poe grew up in southern California and received her undergraduate degree in Human Biology at Stanford University. After graduating in 1987, Poe spent two years at the Department of Veterans Affairs studying the brain waves of pilots during high-G maneuvers.
Poe began working on her PhD in neuroscience at UCLA under the guidance of Ronald Harper. Her thesis concerned the neural mechanisms underlying sleep state in cats.
Poe completed her graduate training in 1995. She then pursued her postdoctoral work at the University of Arizona (UA), under the mentorship of Carol Barnes. Studying the importance of sleep in memory consolidation through recording the firing of neurons during familiar experiences, novel experiences, and during sleep, she concluded that circuits encoding recent memories are likely restructured during REM sleep to selectively strengthen new memories and weaken older ones. She also helped pioneer novel approaches to recording brain activity using coherent fiber optic imaging systems.
At UA, Poe collaborated with Bruce McNaughton and Jim Knierim to research the effects of weightlessness in space on hippocampal maps of the environment. In 1998, they recorded ensembles of place cells in rats using multielectrode arrays and assessed whether weightlessness disrupted the ability of place cells to create cortical maps.
Career and research
In 1998, Poe was recruited to Washington State University, joining the faculty as an assistant professor of Veterinary and Comparative Anatomy and an assistant professor of Pharmacology and Physiology. In 2001, Poe was recruited to the University of Michigan Anesthesiology Department. She became an assistant professor of Molecular and Integrative Physiology, as well as an assistant professor of anesthesiology.
While at the University of Michigan, Poe taught both graduate and undergraduate courses and served on the Sleep Research Society's board of directors. In 2016, Poe returned to UCLA to become a Full Professor in the Department of Integrative Biology and Physiology.
Poe is the principal investigator of the Poe Lab, and her research program has been focused on exploring the mechanisms by which the neural mechanisms of sleep support learning and memory. They research how neural patterns underlying learning are reactivated during sleep, to determine how sleep influences the encoding of memories. Her work has shown that sleep is critical for the synaptic-weakening component of memory consolidation, in which memories of lower importance are pruned. Her lab currently researches the importance of sleep-dependent memory consolidation in the memory effects of diseases (such as Alzheimer's disease, schizophrenia, and post traumatic stress disorder).
Study of sleep and memory consolidation
In 2005, Poe found that rapid eye movement (REM) sleep is important for complex associative learning in rats. After depriving rats of REM sleep for four hours, their improvement at a given task was delayed. Poe then examined the biological underpinnings of the observed theta peaks and troughs during REM sleep. She found that a shift in theta rhythms might occur due to potentiation of distal dendritic synapses and depotentiation of proximal dendritic synapses over learning.
Continuing to research the effects of decreased REM sleep on memory and cognitive performance, Poe assessed how rats' performance in water mazes was affected when non-REM sleep was left intact, but REM sleep was disrupted. They found that REM sleep is not essential for spatial learning, and that when REM sleep was disrupted during initial learning, reversal learning—the ability to disregard old information due to a change in the maze—was enhanced. This suggests that REM may help consolidate incompletely learned items.
Since it is known that antidepressants affect learning and memory, and also inhibit REM sleep, Poe and her colleagues researched the biological underpinnings of how antidepressant-caused inhibition of REM sleep impacts maze learning in rats. Norepinephrine reuptake inhibition, an effect of SNRIs (a class of antidepressant), reduced the length of the transition to REM sleep. This led to worsened re-consolidation of maze memory, as well as an impairment of novel maze learning. Overall, their findings suggested a new model for the purpose of each phase of REM sleep: re-consolidation occurs during REM, novel information is incorporated and consolidated during the transition to REM, and procedural learning is augmented during slow-wave sleep.
During her PhD studies at UCLA, Poe and her colleagues were the first to measure the reflective properties of subcortical neurons in freely moving animals using fiber optic probes, which can be used as an indirect measurement of neural activity with high temporal resolution. Using this tool, they measured the activity of the hippocampus during sleep and wake states in cats. They found that the dorsal hippocampus increased activity during REM sleep, whereas neocortical brain regions decreased their activity.
Advocacy
Poe serves as the Director of Diversity in Outreach and Education Programs at UCLA. She is also the co-faculty director of the Maximizing Access to Research Careers (MARC) Program. In this role, she helps underrepresented students use STEM resources on campus and increase their academic retention, while encouraging them to pursue graduate school.
Poe is a member of the Society for Neuroscience Professional Development Committee, which aims to "further the professional development of neuroscientists" with an emphasis on diversity. Poe also co-directs the Neuroscience Scholars Program through the Society for Neuroscience; admission to the program is restricted to underrepresented students. Poe organizes and teaches the Summer Program in Neuroscience Excellence and Success (SPINES) courses, which aims to help underrepresented students.
Select publications
Swift Kevin M., Keus Karina, Echeverria Christy Gonzalez, Cabrera Yesenia, Jimenez Janelly, Holloway Jasmine, Clawson Brittany C., Poe Gina R. 2019. Sex differences within sleep in gonadally intact rats. Sleep.
Swift Kevin M., Gross Brooks A., Frazer Michelle A., Bauer David S., Clark Kyle J.D., Vazey Elena M., Aston-Jones Gary, Li Yong, Pickering Anthony E., Sara Susan J., Poe Gina R. 2018. Abnormal Locus Coeruleus Sleep Activity Alters Sleep Signatures of Memory Consolidation and Impairs Place Cell Stability and Spatial Memory. Current Biology.
Emrick JJ, Gross BA, Riley BT, Poe GR. 2016. Different Simultaneous Sleep States in the Hippocampus and Neocortex. Sleep.
Watts A, Gritton HJ, Sweigart J, Poe GR. 2012. Antidepressant suppression of non-REM sleep spindles and REM sleep impairs hippocampus-dependent learning while augmenting striatum-dependent learning. The Journal of Neuroscience.
References
Year of birth missing (living people)
Living people
Place of birth missing (living people)
American neuroscientists
American women neuroscientists
Sleep researchers
Stanford University alumni
University of California, Los Angeles alumni
University of California, Los Angeles faculty
University of Michigan faculty
Washington State University faculty
American women academics
21st-century American women | Gina R. Poe | [
"Biology"
] | 1,535 | [
"Sleep researchers",
"Behavior",
"Sleep"
] |
64,189,898 | https://en.wikipedia.org/wiki/Lithium%20selenide |
Properties
Lithium selenide is an inorganic compound that formed by selenium and lithium. It is a selenide with a chemical formula Li2Se. Lithium selenide has the same crystal form as other selenides, which is cubic, belonging to the anti-fluorite structure, the space group is , each unit cell has 4 units.
Synthesis
Lithium Selenide can be synthesized via the reaction between 1.0 equivalents of grey elemental selenium and 2.1 equivalents of lithium trialkylborohydride. The reaction takes place in a solution of THF (tetrahydrofuran) under with stirring (minimum of 20 minutes) at room temperature according to the reaction below: To increase yields and harmful byproducts, naphthalene can be added to the reaction as a catalyst.
Se + 2Li(C2H5)3BH → Li2Se + 2(C2H5)3B + H2
Another method of synthesis involves the reduction of selenium with lithium in liquid ammonia. The Li2Se can be extracted after evaporation of the ammonia.
Uses
One of the most contemporary uses of Li2Se compounds is in the creation of high-density capacitors and batteries. Lithium selenide can act as an excellent prelithiation agent, which helps to prevent the loss of capacity and efficiency during the formation of the solid electrolyte interphase (SEI). Additionally, the high relative conductivity and solubility of the products of lithium selenide decomposition makes it an ideal prelithiation agent. No harmful byproducts or gases are created during this decomposition of Li2Se. One potential drawback to the use of Li2Se is the dissolution and shuttle problems inherent to the transition metals like selenide. To avoid this problem, evolving heterostructure materials can be used to inhibit the dissolution and shuttle effects of Li2Se.
References
Lithium compounds
Selenides
Fluorite crystal structure | Lithium selenide | [
"Chemistry"
] | 413 | [
"Inorganic compounds",
"Inorganic compound stubs"
] |
64,190,059 | https://en.wikipedia.org/wiki/ViaGen%20Pets | ViaGen Pets, based in Cedar Park, Texas, is a division of TransOva Genetics, that offers animal cloning services to pet owners. ViaGen Pets division was launched in 2016.
ViaGen Pets offers cloning as well as DNA preservation services, sometimes called tissue or cell banking.
Technology and patents
ViaGen's subsidiary, Start Licensing, owns a cloning patent which is licensed to their only competitor as of 2018, who also offers animal cloning services.
The cloning process used by both ViaGen and their competitor is somatic cell nuclear transfer, the same as which was used for cloning Dolly the Sheep.
History
ViaGen Pets began by offering cloning to the livestock and equine industry in 2003, and later included cloning of cats and dogs in 2016.
References
Cloning
Companies based in Texas
Companies based in Cedar Park, Texas
American companies established in 2016
Biotechnology companies of the United States
External links
official website | ViaGen Pets | [
"Engineering",
"Biology"
] | 189 | [
"Cloning",
"Genetic engineering"
] |
64,192,814 | https://en.wikipedia.org/wiki/Compsosaurus | Compsosaurus (meaning "elegant lizard") is an extinct genus of phytosaur, a crocodile-like reptile that lived during the Triassic. Its fossils have been found in North Carolina. The type species, Compsosaurus priscus, was named by American paleontologist Joseph Leidy in 1856, although other sources say 1857. Compsosaurus may have been the same animal as the related Belodon.
Only four teeth are known, discovered in the Carnian-Rhaetian-aged coal fields of Chatham County, North Carolina (probably Red Sandstone Formation) and the New Oxford Formation of Pennsylvania.
References
Phytosaurs
Prehistoric reptile genera
Late Triassic reptiles of North America
Triassic geology of North Carolina
Fossils of North Carolina
Triassic geology of Pennsylvania
Paleontology in Pennsylvania
Nomina dubia
Fossil taxa described in 1856
Taxa named by Joseph Leidy | Compsosaurus | [
"Biology"
] | 175 | [
"Biological hypotheses",
"Nomina dubia",
"Controversial taxa"
] |
64,193,429 | https://en.wikipedia.org/wiki/Magnes%20sive%20de%20Arte%20Magnetica | Magnes sive de Arte Magnetica ("The Lodestone, or the Magnetic Art") is a 1641 work by the Jesuit scholar Athanasius Kircher. It was dedicated to Emperor Ferdinand III and printed in Rome by Hermann Scheuss. It developed the ideas set out in his earlier Ars Magnesia and argued that the universe is governed by universal physical forces of attraction and repulsion. These were, as described in the motto in the book's first illustration, 'hidden nodes' of connection. The force that drew things together in the physical world was, he argued, the same force that drew people's souls towards God. The work is divided into three books: 1.De natura et facultatibus magnetis (Of the nature and properties of magnets), 2.Magnes applicatus (Applications of magnets), 3.Mundus sive catena magnetica (The world or the magnetic chain). It is noted for the first use of the term 'electromagnetism'.
The Earth’s magnetic field
The question of the Earth's magnetic field and, in particular, magnetic declination was addressed in Book 2 of Magnes. It was one of great interest in Kircher's time, because it was thought that an understanding of it would help resolve the problem of longitude. The Jesuit order had scholars working in many different parts of the world and was thus able to collect observations on declination. Kircher collected forty-three of these and combined them with observations from a network of other scholars including Mersenne to produce three tables and two lists with a total of 518 values. He proposed that a magnetic map of the Earth could be made with this data, although he did not attempt to do this himself.
Magnetism and Copernican theory
Magnes contained the first response by a Jesuit to the arguments of some heliocentrists who held that magnetism proved the Copernican model of the universe. Kircher was aware that he was the first scholar to mount a critical assault on the heliocentric theory that the Church had condemned as heretical. He did not agree with Galileo and some other scientists of the time that the Earth rotated, so William Gilbert's view that the Earth's magnetic poles had something to do with that rotation was one he did not support. In Kircher's view, the Earth's poles were not the axis of planetary rotation, but the axis around which the stars rotated in the heavenly spheres. Indeed, he argued in Magnes that the Earth stands still because its two magnetic poles are attracted by two celestial reverse poles. Kircher also rejected Kepler's view that the Sun created a magnetic force that caused the planets to rotate around it. He argued that the experimental proofs of magnetism were not sufficient to resolve the question of whether the Earth or the Sun was at the centre of the universe, and did not believe that the behaviour of magnets at a small scale on Earth was a useful guide to how the cosmos worked.
To disprove the idea put forward by Gilbert that the entire Earth was a magnet, Kircher attempted to calculate the force it would exert and the weight it could move if it were so. He concluded that if the Earth were a magnet and the Moon ferrous, the Earth's magnetic force would cause the Moon to crash into it. He likewise argued that if the Earth were a magnet then all the iron on its surface, even in mountains, would be pulled into itself and could not remain where anyone could find it. Kepler had argued that the Sun was like a magnet, holding the planets in their orbits around it. Kircher found this unsatisfactory: how could a single, consistent magnetic force emanating from the Sun explain the different motions of the planets, with their varying speeds and trajectories? How could a force powerful enough to move the planets leave the fixed stars beyond them unmoved? In any case, he argued, it was contrary to the observable behaviour of magnets to suggest that a motionless magnet could draw magnetised bodies around it in orbit.
Magnetic communication
Kircher noted that once objects had been magnetised, they continued to have a relationship with each other even when they were at a distance. He therefore proposed a “machina cryptologica”; this consisted of a number of bottles at some distance from each other, with the letters of the alphabet inscribed around the middle of each bottle. Each also had a lubricated and magnetised stopper bearing a pointer. When the stopper on one bottle is rotated so that the pointer indicates a particular letter of the alphabet, the stopper on the other bottles rotates in the same way. Thus by turning the stopper in one place, someone could send a message to a person observing the bottle at the other end of the machine.
Magnetism and health
While Magnes is noted today primarily for its arguments against Copernicanism, the work addressed a wide variety of different phenomena, including some that have no relationship to the modern scientific understanding of magnetism. There was a scholarly debate in Kircher's time as to whether 'magnetic' powers (i.e. powers of attraction) could be used to heal wounds. Robert Fludd held that if the weapon used to cause a wound was placed against it, the wound would disappear. Kircher argued that there was no magnetic cure - indeed such a cure would be the work of the devil. While he dismissed the notion of a magnetic cure for wounds, he devoted a chapter of Magnes to tarantism as a cure for a spider bite - an example, he believed, of magnetic forces of attraction inherent in music.
Illustrations
Kircher's first work on magnetism, Ars Magnesia, had contained only modest woodcut illustrations. In contrast Magnes was illustrated not only with more than 150 woodcuts but with 32 full-page engraved plates. It was the first of Kircher's works to combine woodcuts with copperplate engravings. These illustrations were both technically challenging to create and expensive to produce. Two of the illustrations were of machines with moving parts, and readers could cut the parts out and use to create working models of the machinery themselves. On reading the first edition soon after it was published, Evangelista Torricelli wrote to his teacher Galileo that it was a pleasure to read and "enriched with a wealth of beautiful engravings."
The frontispiece of the first edition is by Claudio Dagli. It depicts the double-headed imperial eagle of the Hapsburg dynasty. It hangs by a magnetised chain from the imperial crown that supports an orb and a cross. Both the crown and the cross are struck through with magnetised arrows pointing towards a heavenly source, but not directly at the all-seeing eye of god directly above - perhaps a reference to magnetic declination. In one of its claws the eagle holds the crowns of Austria, Hungry and Bohemia, held together by magnetism, while in the other it holds the sceptres of the three realms, similarly linked by magnetic force. Arrows from the bird's outstretched wings project imperial power to the lands below. A lodestone on the eagle's breast carries the dedication to Emperor Ferdinand III and a banner above the eagle's head carries the Latin motto Regna Quis Adiunxit Regnis Nova Sceptra Coronis ("He has added kingdoms to kingdoms and new sceptres to crowns"). A second banner curling around its feet carries the Latin pun Et Boreae Et Austri-Acus (""Needle of the north and south - 'austriacus' also meaning 'Austrian'). In the third edition the dedication to Ferdinand III is replaced on the breast of the eagle by his portrait.
In the first edition there is also a second frontispiece to Book III, designed by Giovanni Battista Rinalducci and executed by Giovanni Battista Ficavazza. This is intended as a graphic illustration of the interconnectedness of scientific disciplines. Fourteen of these are depicted, with theology at the top, accompanied by philosophy, physics, poetry, rhetoric, cosmography, mechanics, perspective, music, natural magic, medicine, astronomy, arithmetic and geography, linked by a golden chain. At the centre of the ring they create sits an emblem of the Mundus Archetypus ('world of archetypes'), containing the all-seeing eye of God, and immediately around it stand representations of Mundus Sidereus ('the world of stars'), Mundus Sublunaris ('the sublunar world') and Microcosmus ('the microcosm'). Weaving between these emblems was a banner bearing the motto 'omnia nodis arcanis connexa quiescunt' ('all things are at rest, connected by secret knots'). This plate was omitted in the second edition but was remade in folio size for the third edition.
The final illustration in the book is of the egg of Columbus standing on its point on a slate and bearing the motto Et nos haec poteramus ("and we have been able to do likewise") - in other words, in producing this work, Kircher had, like Columbus, been able to do something thought to be impossible.
Later editions
The second edition was published in 1643, only two years after the first, showing the work's success. It was completely reset, reducing it from around 900 to 800 pages, with every illustration redrawn. Including a number of corrections, it was published in Cologne by Kalckhoven. Kaspar Schott edited the revised third edition of the book (1654), finding and correcting a great many errors in Kircher's original text. It was the first edition in folio format, published in Rome by Blasius Deuersin and Zanobius Masottus.
Magnetism in other works
Kircher was not the first scholar to write about magnetism. In 1600, William Gilbert published De Magnete ('On the Magnet'), the first modern treatise on magnetism and in 1635, Henry Gellibrand first discovered that magnetic declination changes with time. Among Jesuit scholars, Leonardo Garzoni wrote Trattati della Calamita ('Treatise on the Lodestone') (around 1580) which described the double polarity of magnets. Niccolò Cabeo used Garzoni's manuscript as the basis for his own Philosophia Magnetica. Kircher cited Gilbert, Garzoni and Cabeo in Magnes sive de Arte Magnetica. Magnetism was an important theme in Kircher's 1664 work Mundus Subterraneus as well as his 1667 book Magneticum Naturae Regnum. Many of the magnetic machines lavishly illustrated in the work were later built and displayed in Kircher's museum in Rome.
References
External links
Digital copy of Magnes sive de arte magnetica
Magnetism
Electromagnetism
1641 in science
1641 works
Athanasius Kircher | Magnes sive de Arte Magnetica | [
"Physics"
] | 2,289 | [
"Electromagnetism",
"Physical phenomena",
"Fundamental interactions"
] |
64,195,091 | https://en.wikipedia.org/wiki/Toshiki%20Tajima | is a Japanese theoretical plasma physicist known for pioneering the laser wakefield acceleration technique with John M. Dawson in 1979. The technique is used to accelerate particles in a plasma and was experimentally realized in 1994, for which Tajima received several awards such as the Nishina Memorial Prize (2006), the Enrico Fermi Prize (2015), the Robert R. Wilson Prize (2019), the Hannes Alfvén Prize (2019) and the Charles Hard Townes Award (2020).
Tajima is currently a professor of the University of California, Irvine, and is the Chief Science Officer of TAE Technologies. His works involve plasma physics, laser physics, nuclear fusion, plasma astrophysics, accelerator physics and medical applications of physics.
Early life and career
Tajima was born in the Aichi prefecture of Japan in 1948. He graduated from the University of Tokyo with a bachelor's degree in 1971 and a master's degree in 1973. He then received his doctorate from the University of California, Irvine in 1975, and became a post-doctoral student at the University of California, Los Angeles. In 1980, he became a professor at the University of Texas at Austin, where he remained until 2001.
From 1998 to 2001, Tajima was Special Assistant to the Associate Director at the Lawrence Livermore National Laboratory, and from 2000 to 2002 he worked at the SLAC National Accelerator Laboratory. From 2002, he was director of the Kansai Photon Science Institute of the Japan Atomic Energy Agency, and from 2008 to 2011 he was a professor at the Ludwig Maximilians University of Munich. He has also been at the KEK accelerator since 2008. He is currently a Rostoker Chair Professor at the University of California, Irvine.
Tajima was Chairman of the International Committee for Ultrahigh Intensity Lasers (ICUIL) and Deputy Director of the International Center for Zetta-Exawatt Science and Technology (IZEST) at École Polytechnique (with director Gérard Mourou). He was Blaise Pascal Professor and Einstein Professor at the Chinese Academy of Sciences.
Tajima is also the Chief Science Officer of TAE Technologies, a company founded in 1998 that deals with aneutronic fusion power.
Honors and awards
Tajima is a fellow of the Japan Society for the Promotion of Science and of The Optical Society.
For his work on laser wakefield acceleration, Tajima received the Nishina Memorial Prize in 2006; the Enrico Fermi Prize of the Italian Physical Society in 2015; the Robert R. Wilson Prize of the American Physical Society the Hannes Alfvén Prize of the European Physical Society in 2019; and the Charles Hard Townes Award from The Optical Society in 2020.
Publications
References
Living people
1948 births
Japanese physicists
Plasma physicists
University of Tokyo alumni
University of California, Irvine alumni
University of California, Irvine faculty | Toshiki Tajima | [
"Physics"
] | 567 | [
"Plasma physicists",
"Plasma physics"
] |
64,195,232 | https://en.wikipedia.org/wiki/Hendratta%20Ali | Hendratta Ali is a geoscientist who does work in hydrology, aqueous geochemistry, exploration geology and equity geoscience. Her home institution is the Department of Geosciences at Fort Hays State University. She was awarded the 2021 Geological Society of America Randolph Bromery award and Fort Hays State University President’s Distinguished Scholar Award. Ali is a native of Cameroon.
Education
Ali received her Bachelors of Science, Masters of Science, and Diplôme d'Étude Approfondie from the University of Yaoundé I, Cameroon. She earned her Ph.D. in Geology and Aqueous Geochemistry from the Boone Pickens School of Geology at Oklahoma State University in 2010 with a dissertation entitled Carbon Cycling and Stable Isotope Evolution in Neutral Mine Drainage.
Career and research
Upon joining Fort Hays State University in 2010, where she currently works as an associate professor, she created the petroleum geology program.
She has received over $400,000 in grants at Fort Hays State to further her research.
She worked as an environmental geologist for pedology and hydrogeology for the Chad-Cameroon Pipeline project and freelanced as a technical translator. Ali’s work in chemical geology and carbon cycling has provided several insights into environmental understanding.Her peer-reviewed publications focus on the dissolved inorganic carbon cycling in groundwaters and improving diversity and educational outcomes in the geosciences.
Her research has identified the way that acidification can change the carbonate balance and carbon isotope ratios in water. A study Ali co wrote in 2009 demonstrates that it is possible to identify how acidification may impact the surface of water chemistry through measuring δ¹³C changes and DIC species concentrations.
By measuring the DIC, CO2, and carbon isotopes in different karst waters it Ali found the aquatic plants in these waters produce and store carbon as a result of photosynthesis. This finding goes against traditional beliefs of a straightforward carbon weathering cycle of simple carbon releases to a more complex process. Carbon in this environment can be stored in aquatic plants for an extended amount of time, which helps keep it out of the atmosphere for a long time. By reducing the amount of CO2 Karst environments have the potential to balance the carbon cycle.
In a study published in 2021, she investigated the influence of assumed tide-induced groundwater salinization in the Wouri Estuary of her home country, whereas most studies focused on fully coastal, non-estuarine areas only. Excess salinity compromises potability and has negative implications for industrial use. She discovered that the Douala coastal aquifer was not impacted by the salinization often associated with tidal events but instead proposed that anthropogenic pollution should be acted upon, and connate contamination should be further researched as potential causes.
Ali is also an advocate for justice, equality, diversity and inclusion initiatives at professional, industrial and academic levels in the field of geoscience, specifically to increase representation of marginalized communities such as women and people of colour, and explains that doing so would demonstrate best practices and social responsibility. Within her work as an activist, she co-created a “twenty-point-anti-racism-plan" to help organizations in the science felids foster an “inclusive, equitable, and accessible community.” The overarching goal of the plan was to expose the systemic racism in society, especially in scientific fields, that is not blatantly overt. Her belief is that the guidelines of “identity, value, access, inclusion, equity, and justice” provide the proper framework for anti-racist thinking.
She serves as a Program Director at the National Science Foundation and led a grant IRES: U.S - Cameroon Collaboration Investigating Anthropogenic Perturbations on Carbon Cycling in an Urbanized Tropical Estuary.
Awards
Ali has received many awards, including:
2017 Inspirational Educator Award, American Association of Petroleum Geologists
2017 Rising Star Award, Oklahoma State University
2018 Outstanding Educator Award, Society of Exploration Geophysicists
2020 Presidential Citation for Science and Society, American Geophysical Union
2020 President's Award, Association for Women Geoscientists
2021 President's Distinguished Scholar, Fort Hays State University
2021 Randolph Bromery Award, Geological Society of America
Leadership roles
Ali has served in numerous leadership roles in professional geoscience societies. She was the president of the Kansas Geophysical Society and chaired the Women’s Network Committee and the Youth-Education Committee for the Society of Exploration Geophysicists. She also served as a facilitator for ADVANCEGeo Partnerships training. She also served as supervisor for the Fort Hays State University student chapters of the Society of Exploration Geophysicists and American Association of Petroleum Geologists since 2010.
References
External links
Women geologists
Women geochemists
Cameroonian scientists
Year of birth missing (living people)
Living people
Oklahoma State University alumni
Fort Hays State University people | Hendratta Ali | [
"Chemistry"
] | 994 | [
"Geochemists",
"Women geochemists"
] |
64,195,911 | https://en.wikipedia.org/wiki/Peroxymonophosphoric%20acid | Peroxymonophosphoric acid () is an oxyacid of phosphorus. It is a colorless viscous oil. Its salts are called peroxymonophosphates. Another peroxyphosphoric acid is peroxydiphosphoric acid, .
Preparation
Peroxyphosphoric acids were first synthesized and characterized in 1910 by Julius Schmidlin and Paul Massini via the reaction between phosphorus pentoxide and highly-concentrated aqueous solution of hydrogen peroxide. However, this reaction proceeds very vigorously and is difficult to control. Aside from phosphorus pentoxide, syntheses from metaphosphoric acid and diphosphoric acid were also reported.
A less vigorous method of preparing peroxyphosphoric acid by introducing the inert solvent acetonitrile was described by Gerrit Toennies in 1937. This method was shown to be unsuitable in diethyl ether or isoamyl alcohol.
Contemporary methods
Peroxyphosphoric acid is usually produced by treating phosphorus pentoxide and concentrated hydrogen peroxide within an inert solvent like acetonitrile or carbon tetrachloride.
One method of preparation is the hydrolysis of potassium of lithium peroxydiphosphate in a strong acid such as perchloric acid. The peroxydiphosphate salts can be obtained by electrolysis of their respective phosphate salts.
Peroxydiphosphoric acid is obtained when phosphoric acid is treated with fluorine or oxidized electrolytically.
Properties
Peroxymonophosphoric acid is a colorless, viscous liquid. It is stabilized by an intramolecular hydrogen bond. The compound is a triprotic acid with acid dissociation constants pKa1 = 1.1, pKa2 = 5.5 and pKa3 = 12.8. In aqueous solutions it slowly undergoes hydrolysis to hydrogen peroxide and phosphoric acid.
With excess water, the hydrolysis can be considered pseudo-first order. The half-life for this decomposition is dependent on the pH and temperature, being about 31 hours at 35 °C and 2.5 hours at 61 °C. A solution in acetonitrile also slowly degrades, losing 30% of active oxygen after 26 days of storage at 5 °C. Relatively stable salts can be obtained by neutralization with bases, for example with potassium hydroxide to give the hygroscopic potassium dihydrogenperoxymonophosphate KH2PO5.
Uses and reactions
Peroxyphosphoric acids and peroxyphosphates have few commercial uses.
Reactions with organic compounds
They have been examined in the context of organic synthesis, as an electrophilic reagent for the oxidation of alkenes, alkynes, aromatic compounds and amines. Due to the strongly acidic nature, only relatively acid-stable epoxides can be prepared from alkenes, for example trans-stilbene oxide from trans-stilbene. Less stable epoxides are cleaved or react further; cyclohexene, styrene, and α-methylstyrene yield no isolable epoxides. In the cases of styrene and α-methylstyrene, acid-catalyzed alkyl migrations lead instead to the main products phenylacetic acid and 2-phenylpropionic acid, respectively.
The oxidation of diphenylacetylene at room temperature yields benzil, presumably through an oxirene intermediate.
Peroxymonophosphoric acid is an effective reagent for the hydroxylation of aromatic rings. The conversion of mesitylene to mesitol can be achieved at room temperature in less than four hours.
The compound can be used as an effective oxidizing agent for the Baeyer-Villiger oxidation. Substituted acetophenones can be converted to the corresponding phenyl acetates at 30 °C in high yields. The rate is about 100 times higher in comparison to using peroxybenzoic acid.
Tertiary aromatic amines like dimethylaniline are oxidized to the corresponding amine oxide.
Oxidation of THF with peroxymonophosphoric acid gives γ-butyrolactone.
References
Phosphorus oxoacids
Mineral acids
Substances discovered in the 1910s | Peroxymonophosphoric acid | [
"Chemistry"
] | 913 | [
"Acids",
"Inorganic compounds",
"Mineral acids"
] |
51,407,573 | https://en.wikipedia.org/wiki/Hierarchical%20equations%20of%20motion | The hierarchical equations of motion (HEOM) technique derived by Yoshitaka Tanimura and Ryogo Kubo in 1989, is a non-perturbative approach developed to study the evolution of a density matrix of quantum dissipative systems. The method can treat system-bath interaction non-perturbatively as well as non-Markovian noise correlation times without the hindrance of the typical assumptions that conventional Redfield (master) equations suffer from such as the Born, Markovian and rotating-wave approximations. HEOM is applicable even at low temperatures where quantum effects are not negligible.
The hierarchical equation of motion for a system in a harmonic Markovian bath is
Hierarchical equations of motion
HEOMs are developed to describe the time evolution of the density matrix for an open quantum system. It is a non-perturbative, non-Markovian approach to propagating in time a quantum state. Motivated by the path integral formalism presented by Feynman and Vernon, Tanimura derive the HEOM from a combination of statistical and quantum dynamical techniques.
Using a two level spin-boson system Hamiltonian
Characterising the bath phonons by the spectral density
By writing the density matrix in path integral notation and making use of Feynman–Vernon influence functional, all the bath coordinates in the interaction terms can be grouped into this influence functional which in some specific cases can be calculated in closed form. Assuming a high temperature heat bath with the Drude spectral distribution and taking the time derivative of the path integral form density matrix the equation and writing it in hierarchal form yields
where destroys system excitation and hence can be referred to as the relaxation operator.
The second term in is the temperature correction term with the inverse temperature and the "Hyper-operator" notation is introduced.
As with the Kubo's stochastic Liouville equation in hierarchal form, the counter can go up to infinity which is a problem numerically, however Tanimura and Kubo provide a method by which the infinite hierarchy can be truncated to a finite set of differential equations where is determined by some constraint sensitive to the characteristics of the system i.e. frequency, amplitude of fluctuations, bath coupling etc. The "Terminator" defines the depth of the hierarchy. A simple relation to eliminate the term is found. . With this terminator the hierarchy is closed at the depth of the hierarchy by the final term:
.
The statistical nature of the HEOM approach allows information about the bath noise and system response to be encoded into the equation of motion doctoring the infinite energy problem of Kubo's SLE by introducing the relaxation operator ensuring a return to equilibrium.
Computational cost
When the open quantum system is represented by levels and baths with each bath response function represented by exponentials, a hierarchy with layers will contain:
matrices, each with complex-valued (containing both real and imaginary parts) elements. Therefore, the limiting factor in HEOM calculations is the amount of RAM required, since if one copy of each matrix is stored, the total RAM required would be:
bytes (assuming double-precision).
Implementations
The HEOM method is implemented in a number of freely available codes. A number of these are at the website of Yoshitaka Tanimura including a version for GPUs which used improvements introduced by David Wilkins and Nike Dattani. The nanoHUB version provides a very flexible implementation. An open source parallel CPU implementation is available from the Schulten group.
See also
Quantum master equation
Open quantum system
Fokker–Planck equation
Quantum dynamical semigroup
Quantum dissipation
References
Quantum mechanics | Hierarchical equations of motion | [
"Physics"
] | 738 | [
"Theoretical physics",
"Quantum mechanics"
] |
51,408,006 | https://en.wikipedia.org/wiki/Haze%20%28optics%29 | There are two different types of haze that can occur in materials:
Reflection haze occurs when light is reflected from a material.
Transmission haze occurs when light passes through a material.
The measurement and control of both types during manufacture is essential to ensure optimum quality, acceptability and suitability for purpose of the product.
For instance, in automotive manufacturing, a high quality reflective appearance is desirable with low reflection haze and high contrast whilst in packaging clear, low haze, highly transmissive films are required so that the contents, foods etc., can be clearly observed.
Reflection Haze
Reflection Haze is an optical phenomenon usually associated with high gloss surfaces, it is a common surface problem that can affect appearance quality. The reflection from an ideal high gloss surface should be clear and radiant, however, due to scattering at imperfections in the surface caused by microscopic structures or textures (≈ 0.01 mm wavelength) the reflection can appear milky or hazy reducing the quality of its overall visual appearance.
Causes of this could be due to a number of factors –
Poor dispersion
Method of applying the coating
Variations in drying, curing or baking
Types of materials used in the formulation
Polishing or abrasion
A high gloss surface with haze exhibits a milky finish with low reflective contrast- reflected highlights and lowlights are less pronounced.
On surfaces with haze, halos are visible around the reflections of strong light sources.
Measurement
Measurement of reflection haze is primarily defined under three International test standards:
ASTM E430
ASTM E430 comprises three test methods:
Test method A specifies a 30° angle for specular gloss measurement, 28° or 32° for narrow-angle reflection haze measurement and 25° or 35° for wide-angle reflection haze measurement.
Test method B specifies a 20° angle for specular gloss measurement and 18.1° and 21.9° for narrow-angle reflection haze measurement.
Test method C specifies a 30° angle for specular gloss measurement, 28° or 32° for narrow-angle reflection haze measurement and 15° wide-angle reflection haze measurement.
ASTM D4039
Test method specifies gloss measurements to be made at 20° and 60°, the haze index is then calculated as the difference between the 60° and 20° measurements.
ISO 13803
Source:
Test method specifies a 20° angle for specular gloss measurement and 18.1° and 21.9° for narrow-angle reflection haze measurement.
All test methods specify that measurements should be made with visible light according to CIE spectral luminous efficiency function V(λ) in the CIE 1931 standard observer and CIE standard illuminant C.
As most commercially available glossmeters have gloss measurement angles of 20°, 60° and 85° haze measurement is incorporated at either 20° (ISO 13803 / ASTM E430 method B) or at 20° and 60° ( ASTM D4039). There are however some manufacturers that offer glossmeters with measurement angles of 30° and haze measurement in accordance with ASTM E430 Method A and C but are fewer in number, therefore for the purposes of detailing haze measurement theory only the first three methods will be included.
ISO 13803 / ASTM E430 method B
Both test methods measure specular gloss and haze together at 20° that means light is transmitted and received at an equal but opposite angle of 20°.
Specular gloss is measured over an angular range that is limited by aperture dimensions as defined in ASTM Test Method D523. The angular measurement range for this at 20° is ±0.9° (19.1° - 20.9°). For haze measurement additional sensors are used either side of this range at 18.1° and 21.9° to measure the intensity of the scattered light. Both solid colours and those containing metallics can be measured using this method provided haze compensation is used (as detailed later).
ASTM D4039
This method can only be used on nonmetallic materials having a 60° specular gloss value greater than 70 in accordance with ASTM Test Method D523 / ISO 2813. Haze Index is calculated from gloss measurements made at 20 and 60 degrees as the difference between the two measurements (HI = G60-G20).
As measurements of specular gloss depend largely on the refractive index of the material being measured 20° gloss will change more noticeably than 60° gloss, therefore as haze index is calculated using these two measurements it too will be affected by the refractive index of the material. Evaluations of reflection haze using this test method are therefore confined to samples of roughly the same refractive index.
Haze compensation
It is important to note that the colour (luminous reflectance) of a material can greatly influence the measurement of reflection haze. As colour and haze are both components of scattered light (diffuse reflectance) they must be separated so that only the haze value is quantified; this is also true for metallics or coatings containing metallic pigments where a higher scattering exists.
As test method ASTM D4039 is only suitable for nonmetallic materials of more or less the same refractive index separation of the colour and haze components is not detailed. Haze index calculations and measurements using this test method will therefore produce higher haze results on brighter coloured materials than darker with the same level of haze present. The chart below shows these differences for various colours:-
Both ISO 13803 and ASTM E430 method B require a separate measurement of luminous reflectance, Y, to calculate compensated haze. The tri-stimulus value Y gives a measure of the lightness of the material as defined in ISO 7724-2 requiring a 45°/0° geometry to be used with standard illuminant C and 2° observer (although it is mentioned that slightly different conditions will not result in significant errors). Luminous reflectance measurements, Y, are required on both the sample material and a reference white; ISO 13803 details the use of a BaSO4 standard - barium sulphate, a white crystalline solid having a white opaque appearance and high density as this material is a good substitute for a perfectly reflecting diffusor as defined under ISO 7724-2.
Compensated haze can then be calculated as -
H Comp = H Linear – Y Sample / Y BaSO4
Using the ISO / ASTM method therefore to measure luminous reflectance produces a reliable measurement of Y for non-metallic surfaces as the diffuse component is lambertian, i.e. it is equal in amplitude at all angles in relation to the sample surface.
However, for metallic coatings and those containing speciality pigments, as the particles within the coating reflect the light directionally around the specular angle, little or no metallic reflection is present at the angle at which the luminosity is measured, therefore these types of coatings have an unexpectedly high haze reading. Using a measurement angle which is closer to the region adjacent to the haze angle has proven successful in providing compatible readings on solid colours and also compensating for directional reflection from metallic coatings and speciality pigments
Applications
Generally measurement of reflection haze is confined to high gloss paints and coatings and highly polished metals. Although there has been some degree of success using this measurement method for films it has proven unreliable due to variability caused by changes in the film thickness (internal refraction variations) and the background colour on which the film sample is placed. Generally haze measurement of films is performed using a transmission type hazemeter as described hereafter.
Transmission Haze
Light and transparent materials
When light strikes the surface of a transparent material the following interactions occur –
• Light is reflected from the front surface of the material
• Some light is refracted within the material (depending on thickness) and reflected from the second surface
• Light passes through the material at an angle which is determined by the refractive index of the material and the angle of illumination.
The light that passes through the transparent material can be affected by irregularities within it; these can include poorly dispersed particles, contaminants (i.e. dust particles) and/or air spaces. This causes the light to scatter in different directions from the normal the degree of which being related to the size and number of irregularities present. Small irregularities cause the light to scatter, or diffuse, in all directions whilst large ones cause the light to be scattered forward in a narrow cone shape. These two types of scattering behaviour are known as Wide Angle Scattering, which causes haze due to the loss of transmissive contrast, and Narrow Angle Scattering a measure of clarity or the "see through quality" of the material based on a reduction of sharpness.
These factors are therefore important for defining the transmitting properties of a transparent material-
Transmission – The amount of light that passes through the material without being scattered
Haze – The amount of light that is subject to Wide Angle Scattering (At an angle greater than 2.5° from normal (ASTM D1003))
Clarity – The amount of light that is subject to Narrow Area Scattering (At an angle less than 2.5° from normal)
Measurement
Measurement of these factors is defined in two International test standards-
ASTM D1003
ASTM D1003 comprises two test methods:
Procedure A – using a Hazemeter
Procedure B – using a Spectrophotometer
BS EN ISO 13468 Parts 1 and 2
Source:
Part 1 – Using a single beam Hazemeter
Part 2 – Using a dual beam Hazemeter
The test methods specify the use of a Hazemeter as shown below -
A collimated beam of light from a light source (ASTM D1003 - Illuminant C, BS EN ISO 13468 Parts 1 and 2 - Illuminant D65 ) passes through a sample mounted on the entrance port of an integrating sphere.
The light, which is uniformly distributed by a matte white highly reflective coating on the sphere walls, is measured by a photodetector positioned at 90° from the entrance port. A baffle mounted between the photodetector and the entrance port prevents direct exposure from the port.
The exit port immediately opposite the entrance port contains a light trap to absorb all light from the light source when no sample is present. A shutter in this exit port coated with the same coating as the sphere walls allows the port to be opened and closed as required.
Total transmittance is measured with the exit port closed.
Transmittance haze is measured with the exit port open.
Commercially available Hazemeters of this type perform both measurements automatically, the only operator interaction being the placement of the sample material on the measurement (entrance) port of the device.
See also
Gloss (paint)
Visual appearance
Distinctness of image
Transparency meter
References
External links
Reflection Haze measurement theory
Optical phenomena | Haze (optics) | [
"Physics"
] | 2,173 | [
"Optical phenomena",
"Physical phenomena"
] |
51,408,489 | https://en.wikipedia.org/wiki/Air-Ink | AIR-INK is a proprietary brand of ink and composites products made by condensing carbon-based gaseous effluents generated by air pollution due to incomplete combustion of fossil fuels. Founded by Graviky Labs, a spin-off group of MIT Media Lab, AIR-INK produces its materials through a step-by-step process which primarily involves capturing of emissions, separation of carbon from the emissions, and then mixing of this carbon with different types of oils and solutions to achieve advanced material properties. It uses a patented device and technique called 'KAALINK' to carry out the filtration of soot, which contains carbon and other polluting agents like heavy metals and polycyclic aromatic hydrocarbon.
AIR-INK is marketed as a solution to air pollution and its negative effects on human life, by allowing the print industry to offset its carbon. Dubbed as "the first ink made out of recycled air pollution," its products were used in June 2016 in association with Heineken to create street art and murals in Hong Kong's Sheung Wan district. 30–50 minutes of car pollution can supply enough carbon to fill one AIR-INK pen.
History
Anirudh Sharma, the founder of Graviky Labs, first conceived the idea of AIR-INK during an experiment at MIT, while designing a printer that could print with carbon nanoparticles. Sharma and his team spent close to three years researching how to purify and repurpose carbon soot from auto and factory emissions, a major contributor to air pollution and global carbon footprint. In 2013, the Fluid Interfaces research group, at the Massachusetts Institute of Technology demonstrated the process of converting carbon residue into ink for use in an inkjet cartridge.
In 2016, AIR-INK products were given to graphic artists in Hong Kong, which is known for its high air pollution, who were requested to paint murals. An artist who participated in this campaign said of the product, "genius, and deserves a chance."
Technology
Soot composed of 2.5-micrometer black carbon particles found in petrol or diesel carbon emissions is captured from the tailpipes of cars and diesel generators through a device called 'Kaalink.' A separate ensures that carbon particulate is recycled into safe inks without heavy metals/toxins A single Air Ink pen contains 30–50 minutes of air pollution. The emissions from 2,500 hours of driving one standard diesel vehicle produces about 150 litres of ink.
'Kaalink'
Kaalink is a cylindrical device that is retrofitted into a diesel generators' exhaust system or exhaust pipe to collect the emissions. It can collect up to 93% of the total exhaust, which is then processed to remove heavy metals and carcinogens. The end-product from this device is a purified carbon-based pigment. Kaalink has been tested on cars, trucks, motorcycles and fishing boats in Bangalore and Hong Kong. The company now has started to work on capturing pollution from static sources of emission such as diesel generators. Third party polluters also send in their PM2.5 pollution to Graviky's recycling warehouses.
Some critics have proposed this device will act similar to a diesel particulate filter, which has been shown to increase back pressure on the engine, thereby marginally affecting the efficiency of the engine, resulting in a loss of power, decreased mileage, and increased emissions.
References
Further reading
External links
Companies based in Bengaluru
Emissions reduction
Indian brands
Inks
Kickstarter-funded products
2016 establishments in Karnataka | Air-Ink | [
"Chemistry"
] | 719 | [
"Greenhouse gases",
"Emissions reduction"
] |
51,408,572 | https://en.wikipedia.org/wiki/HeiQ%20Materials%20AG | HeiQ (German pronunciation: [ˈhaɪkju]) is HeiQ Group. The mother company of the group is a Swiss specialty chemistry company, HeiQ Materials AG, headquartered in Zurich, Switzerland. It was founded in 2005 as a spin-off of Swiss Federal Institute of Technology Zurich (ETH).
HeiQ produces and sells textile finishing and other auxiliaries. But its core business activity is to conduct co-joint research and development projects with consumer textile products brands such as those that produce and market apparels (e.g. Patagonia, Mammut, Hanes) and home furnishings (e.g. Bekeart, IKEA) or textile producers for textile finishing to achieve effects that are currently not in market or not optimized to certain products.
For the Deepwater Horizon oil spill that began in April 2010 in the Gulf of Mexico, HeiQ, TWE Group and Beyond Surface Technologies jointly developed an oil-absorbing, water-repelling, nonwoven fabric, in the name Oilguard for oil relief efforts. The product was intended for beach protection against oil spills and was applied to the shoreline. This allows for the fabric to absorb crude oil while repelling the seawater. This innovation was rewarded the Swiss Technology Award (2010) and the Swiss Award (2013). The water-repelling property of Oilguard is achieved with a textile finishing that creates the Lotus Effect on the surface of the non-woven fabric. The non-fluorinated finishing makes the fabric only water repellent but not oil repellent, therefore the fabric absorbs oil crudes but not the seawater.
Due to the COVID-19 pandemic, HeiQ announced the launch of an "antiviral and antimicrobial textile treatment that was tested effective against coronavirus".
The HeiQ Group consists of HeiQ Materials AG and its subsidiaries in North Carolina (HeiQ ChemTex), Shanghai, Taiwan, Hong Kong, Portugal and Australia.
References
Nanotechnology | HeiQ Materials AG | [
"Materials_science",
"Engineering"
] | 415 | [
"Nanotechnology",
"Materials science"
] |
51,408,785 | https://en.wikipedia.org/wiki/Flexal%20mammarenavirus | Flexal mammarenavirus (also known as the Flexal virus or FLEV, and previously known by the laboratory code BeAn 293022) is a mammarenavirus: an arenavirus with a mammalian host. It was first found in semiaquatic rodents of the genus Oryzomys in tropical forest in the Pará area of Brazil.
It is a member of Clade A of the Tacaribe (or "New World") serocomplex of the family Arenaviridae. Laboratory workers infected by Flexal virus have exhibited febrile illness.Flexal virus is listed as a UN 2814 Category A infectious substance.
References
External links
Flexal virus strain BeAn 293022 glycoprotein precursor and nucleocapsid protein genes, complete cds
ArboCat Virus: Flexal (FLEV)
Arenaviridae
Viral diseases | Flexal mammarenavirus | [
"Biology"
] | 180 | [
"Virus stubs",
"Viruses"
] |
51,409,431 | https://en.wikipedia.org/wiki/Palit%20Microsystems | Palit Microsystems, Ltd. is a Taiwanese-based company, founded in 1988. It is known for exclusive manufacturing of graphic cards on the basis of Nvidia and ATI graphic chipsets. Palit's factories are found in mainland China, while the offices are in Taipei, Taiwan, a logistics center in Hong Kong, China, and branch office in Germany.
Palit Microsystems runs two major brands, Palit, and Gainward, which target different global markets, and other brands like Daytona, Galaxy (GALAX), Vivkoo, Yuan, KFA2 (Kick Fuckin Ass²) and XpertVision. It also contract-manufactures graphics cards for other companies. In 2013 Palit Microsystems surpassed ASUSTek, becoming the biggest graphics card vendor by volume. Palit Microsystems' monthly maximum capacity reaches 1,200,000 units. As of 2011 Palit's production share was about at 20–25% of world market of graphics solutions. In the same time on the Russian market Palit had more than 40%, in Ukraine – about 30%.
In 2005 Palit Microsystems acquired the Gainward brand, company and branch Gainward Europe GmbH for $1 million of Taiwan-based TNC Industrial.
See also
Gainward
References
Computer companies of Taiwan
Computer hardware companies
Companies based in Taipei
Electronics companies of Taiwan
Graphics hardware companies
Taiwanese companies established in 1988 | Palit Microsystems | [
"Technology"
] | 286 | [
"Computer hardware companies",
"Computers"
] |
51,409,459 | https://en.wikipedia.org/wiki/Intelsat%2033e | Intelsat 33e, also known as IS-33e, was a high throughput (HTS) geostationary communications satellite operated by Intelsat and designed and manufactured by Boeing Space Systems on the BSS 702MP satellite bus. It was the second satellite of the EpicNG service, and covered Europe, Africa and most of Asia from the 60° East longitude, where it replaced Intelsat 904. It had a mixed C-band, Ku-band and Ka-band payload with all bands featuring wide and C- and Ku- also featured spot beams.
After nearly eight years in service, the satellite broke into at least 57 pieces on 19 October 2024. As of December 2024, over 700 pieces of debris have been detected.
Satellite description
Intelsat 33e was designed and manufactured by Boeing on the Boeing 702MP satellite bus. It had a launch mass of and a design life of more than 15 years. When stowed for launch, the satellite measured .
It was powered by two solar panels, with four panels each, of triple-junction GaAs solar cells. The 702MP platform was designed to generate between 6 kW and 12 kW, but Intelsat 33e was designed to generate 13 kW at the end of its design life.
Its payload was the second high throughput EpicNG deployment. The EpicNG is characterized by the implementation of frequency reuse due to a mix of frequency and polarization in small spot beams. Not only applied to the classical High-throughput satellite (HTS) Ka-band, but also applying the same technique in Ku-band and C-band. The EpicNG series also keep the use of wide beams to offer high throughput and broadcast capabilities in the same satellite.
In the case of Intelsat 33e, the C-band side had 20 transponders with a total downlink bandwidth of 2,670 MHz. The spot beams offered high bandwidth for Europe, Central Africa, Middle East, Asia and Australia, and a wide beam covered sub-Saharan Africa. The Ku-band had 249 transponder equivalents, for a total downlink bandwidth of 9,194 MHz. The Ku-band spot beams covered Europe, Africa, the Middle East and Asia, while a wide beam was able to broadcast to Europe, Middle East and Asia. The Ka-band payload had 450 MHz of bandwidth on a global beam centered at its position.
History
In July 2009, Intelsat became the first customer of the Boeing 702MP satellite bus, when it placed an order for four spacecraft, Intelsat 21, Intelsat 22, Intelsat 27 and the first EpicNG satellite, Intelsat 29e. In May 2013, Intelsat made a second order for an additional four EpicNG satellites, the first of which would be Intelsat 33e.
On 15 July 2016, Senior Space Program Managers Richard Laurie and Brian Sing blogged that they had been at the Boeing factory overseeing the transport preparations for Intelsat 33e to French Guiana. There it would join another Intelsat satellite, Intelsat 36, for integration on the Ariane 5 ECA launcher, which was expected to launch on 24 August 2016. On 22 July 2016, Intelsat announced that Intelsat 33e had arrived to the Guiana Space Center for launch preparations. It also announced not only communication but aeronautical and maritime mobility clients that were expecting the satellite service. On 27 July 2016, it was explained that the satellite had traveled by truck from the factory to an airport in California, where it was loaded in an Antonov 124. It flew to Florida for a refuelling stop and then flew straight to Kourou airport. At the French launch site, even though Intelsat is the owner of the two passengers of the Ariane 5 ECA VA 232 flight, they have separate launch teams. Each satellite is built by a different manufacturer, and it has a different supervisor team within Intelsat.
On 24 August 2016, at 22:16:01 UTC, after a slight delay due to a rocket issue, the Ariane 5 ECA VA-232 flight launched from Guiana Space Center ELA-3, with Intelsat 33e and Intelsat 36. At 22:44 UTC, Intelsat 33e separated from the rocket's upper stage. After 41 minutes of flight, both satellites had separated successfully. Intelsat confirmed that it had received the satellites signals as expected after separation. Arianespace estimated the insertion orbit as 248.7 km × 35,858 km × 5.98°, very close to the target of 249.0 km × 35,879 km × 6.00°.
On 9 September 2016, Intelsat announced that due to a malfunction in the LEROS-1c primary thruster, it would require more time for orbit rising and thus the service date had been moved from the last quarter of 2016 to the first of 2017. On 22 September 2016, insurance officials estimated that the main propulsion failure would not reduce the on orbit life of the spacecraft more than 18 months. This could translate to an insurance claim by Intelsat of around 10% (1.5 years) of the satellite service life, which could have a value close to US$40 million. Intelsat 33e entered service on 29 January 2017, three months later than planned.
In August 2017, another propulsion issue appeared, leading to larger-than-expected propellant usage to control the satellite attitude during the north/south station keeping maneuvers. This issue reduced the orbital life-time by about 3.5 years.
Disintegration
Late on 19 October 2024, U.S. Space Command reported that the satellite had broken up into about 20 pieces at approximately 04:30 UTC that morning. At least 700 pieces of space debris associated with the event have since been detected. Intelsat declared the satellite a total loss on 21 October 2024. The 2024 loss was not insured, unlike the earlier malfunction of the satellite in 2016.
The satellite's predecessor, Intelsat 29e, also suffered a premature failure and was rendered inoperable after only three years in service.
References
Communications satellites in geostationary orbit
Satellites using the BSS-702 bus
Spacecraft launched in 2016
Intelsat satellites
Ariane commercial payloads
Spacecraft that broke apart in space | Intelsat 33e | [
"Technology"
] | 1,275 | [
"Space debris",
"Spacecraft that broke apart in space"
] |
51,409,751 | https://en.wikipedia.org/wiki/Tuber%20foetidum | Tuber foetidum is a species of truffle in the genus Tuber (fungus). It was first described scientifically in 1831 by the Italian doctor and mycologist Carlo Vittadini. It is characterized by its foetid odour, and minute brownish bumps on the surface of the fruitbody. A rare species, it is found in Europe. It associates with oak and beech in southern Europe, and with larch in the United Kingdom. Molecular analysis indicates that T. foetidum is closely related to T. maculatum.
References
External links
Fungi described in 1831
Fungi of Europe
foetidum
Fungus species | Tuber foetidum | [
"Biology"
] | 134 | [
"Fungi",
"Fungus species"
] |
51,410,433 | https://en.wikipedia.org/wiki/Ann%20M.%20Valentine | Ann M. Valentine is an American bioinorganic chemist whose research focuses on biomineralization, the uptake and transport of metals and their medical applications in areas such as cancer research. She has received awards including the 2014 AICChemical Pioneer Award "for her outstanding contributions towards advancing the science of chemistry and impacting the chemical profession" and the 2009 Paul D. Saltman Award for Metals in Biology for "outstanding contributions to the field of metals in biology" and "groundbreaking work on the structures and reactions of complexes containing titanium."
Education
Valentine earned a Bachelor of Science in chemistry from the University of Virginia in 1993. As an undergraduate, she researched aluminum inhibition of magnesium-dependent enzymes with Timothy L. Macdonald. She studied with Stephen J. Lippard at the Massachusetts Institute of Technology and earned her PhD in 1998.
Career
From 1998-2001, Valentine worked with Stephen J. Benkovic as a postdoctoral fellow at Pennsylvania State University. She published on the topics of enzyme kinetics, metallo-beta-lactamase, and the mechanics of replisome and primase in DNA replication.
In 2001, Valentine joined the chemistry faculty of Yale University. During her years there, she was able to begin research into the biological role of titanium, a question which she had long found intriguing. Valentine had become interested in the element early in her graduate career: in the early 1990s, titanium was not recognized as important in bioinorganic chemistry, but was believed by some (including her advisor) to be a candidate for future investigation.
In 2011, Valentine became an associate professor at Temple University where she specializes in environmental, material, and medicinal aspects of inorganic and biological chemistry. Her research group focuses on bioinorganic chemistry, especially nicatransferrin, Ti4+ ions, and biotitanification.
Outreach and mentorship
Valentine has participated in the Philadelphia Area Girls Enjoying Science (PAGES) and Temple Minority Access to Research Careers (MARC) programs. Via the Temple Teaching and Learning Center, she has acted as a mentor for students in high-attrition courses.
Awards and honors
2014, American Institute of Chemists Chemical Pioneer Award
2009, Paul D. Saltman Award for Metals in Biology
2007, American Chemical Society PROGRESS/Dreyfus Lectureship Award
2006, American Cancer Society Research Scholar Award
2004, National Science Foundation CAREER award
2003, Research Corporation Research Innovation Award
2015 and 2021, Honors Professor of the Year. 2016, Dean's Distinguished Teaching Award, Temple University
References
Bioinorganic chemists
21st-century American chemists
American women chemists
University of Virginia alumni
Massachusetts Institute of Technology alumni
Yale University faculty
Temple University faculty
Living people
Year of birth missing (living people)
American women academics
21st-century American women scientists | Ann M. Valentine | [
"Chemistry"
] | 557 | [
"Bioinorganic chemistry",
"Bioinorganic chemists"
] |
51,410,477 | https://en.wikipedia.org/wiki/Women%20in%20Antarctica | Women have been exploring the regions around Antarctica for many centuries. The most celebrated "first" for women in Antarctica was in 1935 when Caroline Mikkelsen became the first woman to set foot on one of Antarctica's islands. Early male explorers, such as Richard Byrd, named areas of Antarctica after wives and female heads of state. As Antarctica moved from a place of exploration and conquest to a scientific frontier, women worked to be included in the sciences. The first countries to have female scientists working in Antarctica were the Soviet Union, South Africa and Argentina.
Besides exploring and working as scientists, women have also played supportive roles as wives, fund-raisers, publicists, historians, curators and administrators of organizations and services that support Antarctic operations. Many early women on Antarctica were the wives of explorers. Some women worked with Antarctica from afar, crafting policies for a place they had never seen. Women who wished to have larger roles in Antarctica and on the continent itself had to "overcome gendered assumptions about the ice and surmount bureaucratic inertia". As women began to break into fields in Antarctica, they found that it could be difficult to compete against men who already had the "expeditioner experience" needed for permanent science positions. Women who were qualified for expeditions or jobs in Antarctica were less likely to be selected than men, even after a 1995 study by Jane Mocellin showed that women cope better than men with the Antarctic environment.
Historic barriers against inclusion
Most early policies and practices, including the construction and creation of Antarctic organizations, were created initially by men. Women were originally excluded from early exploration in Antarctica based on the opinion that women could not handle the extremes in temperature or crisis situations. Vivian Fuchs, who was in charge of the British Antarctic Survey in the 1960s, believed that women could not carry heavy equipment and that Antarctic facilities were unsuitable for women. The United States believed for many years that the climate of Antarctic was too harsh for women.
Antarctica was seen by many men as a place where men could imagine themselves heroic conquerors. In Western culture, frontier territories are often associated with masculinity. Antarctica itself was envisioned by many male explorers as a "virginal woman" or "monstrous feminine body" to be conquered by men. Women were often "invoked in terms of place naming and territorial conquest and later even encouraged to have babies in Antarctica." Using women as territorial conquest is literal in the way that Argentina flew pregnant women to Antarctica to give birth and stake a national claim to the area.
Silvia Morella de Palma was the first woman to give birth in Antarctica, delivering Emilio Palma at the Argentine Esperanza base 7 January 1978.
Men enjoyed having a space that was free of women and which, in the late 1940s, "allowed them to continue the kind of male companionship and adventure they had enjoyed during the Second World War." In one news article about Antarctica written in 1958, the writer describes the use of dazzlement: "On the womanless continent, the purpose of the dazzlement is not to catch the eye of a flirtatious blonde, but to attract spotters in the event that the explorers become lost in the frozen waste." Men's space in Antarctica resisted change. In the 1980s, there was an attempt by men to memorialize the "Sistine ceiling" of the Weddell hut in Antarctica as an Australian national heritage site of "high significance." The "Sistine ceiline" was covered in 92 different pinups of women from the 1970s and 1980s. This represented a "male's only club" in which participants believed women would spoil the "purity of a homosocial work, and play, environment." In 1983, the San Bernardino County Sun newspaper published an article about Antarctica stating that it "is still one of the last macho redoubts, where men are men and women are superfluous." One scientist, Lyle McGinnis, who had been going to Antarctica since 1957, resented women in the field saying that "men never grouse." He believed that women complained and needed "comfort." Not all men felt that way. Other men felt that women's presence made life in Antarctica better and one male engineer stated that without women around, "men are pigs." Sociologist Charles Moskos stated that as more women are introduced to a group, there is less aggression and a "more civil culture develops."
Many of the careers in Antarctica are in the sciences and women faced barriers there as well. As women attempted to work in science, arguments using biological determinism, evolutionary psychology and popular notions of neurobiology were used as excuses as to why there were fewer women in the sciences. These arguments described how "women are ill-adapted on evolutionary grounds for science and the competitive environment of the laboratory." Some women described feeling that they were "a bit of a joke" working in Antarctica and felt that men regarded them as incapable.
Antarctic exploration and science research was often facilitated by national navies, who often did not want women on their ships. The United States Navy used the excuse that "sanitation facilities were too primitive" on Antarctica as an excuse to bar women. The U.S. Navy also considered Antarctica a "male-only bastion." Admiral George Dufek said in 1956 that "women would join American Teams in the Antarctic over his dead body." He also believed that women's presence on Antarctica "would wreck men's illusions of being heroes and frontiersmen." Military groups also were worried about "sexual misconduct."
Change was slow as women began to try to become part of Antarctic exploration and research. An article run in The Daily Herald newspaper of Chicago in 1974 described women finally coming to Antarctica as integrating the "land with a definite feminine touch." The article described women's perfumed smells, ways of entertaining guests on Antarctica and the "dainty feet" of Caroline Mikkelsen. Eventually both the "presence and impact of female Antarctic researchers has increased rapidly."
Early women involved in Antarctica
Oral records from Oceania indicate that women explorers may have traveled to the Antarctic regions like male explorers Ui-te-Rangiora around 650 CE and Te Ara-tanga-nuku in 1000 CE, but this is unconfirmed. The first western woman to visit the Antarctic region was Louise Séguin, who sailed on the Roland with Yves Joseph de Kerguelen in 1773.
The oldest known human remains in Antarctica was a skull that belonged to a young Indigenous Chilean woman on Yamana Beach at the South Shetland Islands, which dates back to 1819 to 1825. Her remains were found by the Chilean Antarctic Institute in 1985.
In the early twentieth century, women were interested in going to Antarctica. When Ernest Shackleton advertised his 1914 Antarctic expedition, three women wrote to him, requesting to join. The women never became part of the journey. In 1919, newspapers reported that women wanted to go to Antarctica, writing that "several women were anxious to join, but their applications were refused." Later, in 1929, twenty-five women applied to the British, Australian and New Zealand Antarctic Research Expedition (BANZARE). They were also rejected. When a privately funded British Antarctic Expedition was proposed in 1937, 1,300 women applied to join. None of those 1,300 were accepted. After 3 years of attempted funding the expedition was cancelled with the onset of World War Two.
Women who were wives of explorers who were left behind "endured years of loneliness and anxiety." Women like Kathleen Scott raised money for their husbands' journeys.
The first women involved in exploration of Antarctica were wives and companions of male travelers and explorers. Women accompanied men as "whaling wives" to Antarctic waters. The first women to see the continent of Antarctica was Norwegian Ingrid Christensen and her companion, Mathilde Wegger, both of whom were traveling with Christensen's husband. The first woman to step onto the land of Antarctica, an island, was Caroline Mikkelsen in 1935. Mikkelsen only briefly went ashore and was also there with her husband. Later, after her husband died, Mikkelsen remarried and didn't talk about her experience in Antarctica in order "to spare his feelings." Christensen went back to Antarctica three times after her first glimpse of the land. She eventually landed at Scullin monolith, becoming the first woman to set foot on the Antarctic mainland. She was followed by her daughter, Augusta Sofie Christensen, and two other women, Lillemor Rachlew and Solveig Widerøe. Because the women believed the landing wasn't an actual "first," they didn't make much of their accomplishment.
In the years of 1946 and 1947, Jackie Ronne and Jennie Darlington were the first women to spend the year in Antarctica. When Ronne and Darlington decided to accompany their husbands in 1946 to Antarctica, men on the expedition "signed a petition trying to stop it happening." Ronne worked as the mission's "recorder." Ronne and Darlington both wrote about their experiences on the ice and, in the case of Darlington's book, about how conflict between team members also "strained relations between the two women." One of the ways that Darlington tried to fit in with the men of the group was to make herself as "inconspicuous within the group as possible." One man, first seeing Darlington arrive at the Antarctic base, "fled in fright, thinking that he'd gone mad." Both women, upon returning from Antarctica, downplayed their own roles letting "their husbands take most of the honour."
In 1948, the British diplomat, Margaret Anstee, was involved in the Falkland Islands Dependency Survey (FIDS) and helped make policy for the program.
Further exploration and science
Women scientists first began researching Antarctica from ships. The first woman scientist, Maria V. Klenova of the Soviet Union, worked on the ships Ob and Lena just off the Antarctic coastline in 1955 to 1956. Klenova's work helped create the first Antarctic atlas. Women served on Soviet Union ships going to Antarctica after 1963. The first women to visit a US station and the first to fly to Antarctica were Pat Hepinstall and Ruth Kelley, Pan Am flight attendants who spent four hours on the ground at the McMurdo Station on 15 October 1957.
Often women going to Antarctica had to be approved in both official and unofficial ways. An early candidate for becoming one of the first women scientists to go to Antarctica was geologist Dawn Rodley. She had been approved of not only by the expedition sponsor, Colin Bull, but also by the wives of the male team-members. Rodley was set to go in 1958, but the United States Navy, who were in charge of Operation Deep Freeze, refused to take her to Antarctica.
The Navy decided that sending a four-woman team would be acceptable and Bull began to build a team including Lois Jones, Kay Lindsay, Eileen McSaveney and Terry Tickhill. These four women were part of the group who became the first women to visit the South Pole. Jones's team worked mainly in Wright Valley. After their return, Bull found that several of his male friends resented the addition of women and even called him a "traitor".
The first United States all-female team was led by Jones in 1969. Her team, which included the first women to set foot on the South Pole, were used by the navy as a publicity stunt. They were "paraded around" and called "Powderpuff explorers". The first United States woman to step into the Antarctic interior in 1970 was engineer Irene C Peden, who also faced various barriers to her working on the continent. Peden described how a "mythology had been created about the women who'd gone to the coast – that they had been a problem," and that since they had not published their work within the year, they were "heavily criticized." Men in the Navy in charge of approving her trip to Antarctica were "dragging their feet", citing that there were not women's bathrooms available and that without another female companion, she would not be allowed to go. The admiral in charge of transportation to Antarctica suggested that Peden was trying to go there for adventure, or to find a husband, rather than for her research. Despite her setbacks, including not receiving critical equipment in Antarctica, Peden's research on the continent was successful.
The first two U.S. woman to winter at a U.S. Antarctic research station were Mary Alice McWhinnie and
Mary Odile Cahoon. Mary Alice was the station science leader (chief scientist) at McMurdo Station in 1974 and Mary Odile was a nun and biologist. United States women in 1978 were still using equipment and arctic clothing designed for men, although "officials said that problem is being quickly remedied." American Ann Peoples became the manager of the Berg Field Center in 1986, becoming the first woman to serve in a "significant leadership role".
British women had similar problems to the Americans. The director of the British Antarctic Survey (BAS) from 1959 to 1973 was Vivian Fuchs, who "firmly believed that the inclusion of women would disrupt the harmony and scientific productivity of Antarctic stations." British women scientists started working on curating collections as part of the BAS prior to being allowed to visit Antarctica. Women who applied to the BAS were discouraged. A letter from BAS personnel sent to a woman who applied in the 1960s read, "Women wouldn't like it in Antarctica as there are no shops and no hairdresser." The first BAS woman to go to Antarctica was Janet Thomson in 1983 who described the ban on women as a "rather improper segregation." Women were still effectively barred from using UK bases and logistics in 1987. Women didn't overwinter at the Halley Research Station until 1996, forty years after the British station was established.
Argentina sent four women scientists, biologist Irene Bernasconi, bacteriologist María Adela Caría, biologist Elena Martinez Fontes and algae expert Carmen Pujals, to Antarctica in 1968. They were the first group of female scientists to conduct research in Antarctica. Bernasconi was the first woman to lead an Antarctic expedition. She was aged 72 at the time. Later, in 1978, Argentina sent a pregnant woman, Silvia Morello de Palma, to the Esperanza Base to give birth and to "use the baby to stake [their] territorial claims" to Antarctica.
Once Australia opened up travel to Antarctica for women, Elizabeth Chipman, who first worked as a typist at Casey Station in 1976, chronicled all of the women to travel there up to 1984. Chipman worked to find the names of all women who had ever been to or even near Antarctica and eventually donated 19 folio boxes of her research to the National Library of Australia.
Women gain ground
The National Science Foundation (NSF) started long-range planning in 1978, looking towards facilities that could accommodate a population made up of 25% women. In the 1979–1980 season, there were only 43 women on the continent. By 1981, there were nearly one woman for every ten men in Antarctica. In 1983, the ratio was back to 20 men for every woman. In the 1980s, Susan Solomon's research in Antarctica on the ozone layer and the "ozone hole" causes her to gain "fame and acclaim."
In Spain, Josefina Castellví, helped coordinate and also participated in her country's expedition to Antarctica in 1984. Later, after a Spanish base was constructed in 1988, Castellví was put in charge after the leader, Antoni Ballester, had a stroke.
The first female station leader on Antarctica was Australian, Diana Patterson, head of Mawson Station in 1989. The first woman station leader in charge of an American Antarctic station was LT Trina Baldwin, CEC, USN (Civil Engineer Corps, United States Navy). The first all-female overwintering group was from Germany and spent the 1990–1991 winter at Georg von Neumayer. The first German female station leader and medical doctor was Monika Puskeppeleit. In 1991 In-Young Ahn was the first female leader of an Asian research station (King Sejong Station) and the first South Korean woman to step onto Antarctica.
There were approximately 180 women in Antarctica during the 1990–1991 season. Women from several different countries were regular members of overwintering teams by 1992. The first all-women expedition reached the South Pole in 1993. Diana Patterson, the first female station leader on Antarctica, saw change coming in 1995. She felt that many of the sexist views of the past had given way so that women were judged not by the fact that they were women, but "by how well you did your job."
During the 1994 austral winter, women managed all three of the American Antarctic stations: Janet Phillips at Amundsen-Scott South Pole Station, Karen Schwall at McMurdo Station and Ann Peoples at Palmer Station.
Social scientist, Robin Burns, studied the social structures of Antarctica in the 1995–1996 season. She found that while many earlier women struggled, there was more acceptance of women in Antarctica during the 1995 - 1996 season. One of the station managers, Ann Peoples, felt that a tipping point had been reached during the 1990s and that life for women on Antarctica became more normal. There were still men in Antarctica who were not afraid to voice their opinion that women should not "be on the ice," but many others enjoyed having "women as colleagues and friends." Women around this time began to feel like it was "taken for granted now that women go to the Antarctic."
Studies done in the early 2000s showed that women's inclusion in Antarctic groups were beneficial overall. In the early 2000s, Robin Burns had found that female scientists who enjoyed their experience in Antarctica, were the ones who were able to finish their scientific work and to complete their projects.
Recent history
American Lynne Cox swam a mile in Antarctic water in 2003.
In 2005, writer Gretchen Legler described how there were many more women in Antarctica that year and that some were lesbians. International Women's Day in 2012 saw more than fifty women celebrating in Antarctica and who made up 70% of the International Antarctic Expedition. In 2013, when the Netherlands opened their first Antarctic Lab, Corina Brussaard was there to help set it up.
Homeward Bound was a 10-year program designed to encourage women's participation in science and planned to send the first large (78 member) all-women expedition to Antarctica in 2016. The first group, consisting of 76 women, arrived in Antarctica for three weeks in December 2016. Fabian Dattner and Jess Melbourne-Thomas founded the project and the Dattner Grant provided funding. Each participant contributed $15,000 to the project. Homeward bound included businesswomen and scientists who look at climate change and women's leadership. The plan was to create a network of 1,000 women who would become leaders in the sciences. The first voyage departed South America in December 2016
An all-woman team of United Kingdom Army soldiers, called Exercise Ice Maiden, started recruiting members in 2015 to cross the continent under their own power in 2017. It intended to study women's performance in the extreme antarctic summer environment. A team of six women completed the journey in 62 days after starting on 20 November 2017.
Currently, women make up 55% of membership in the Association of Polar Early Career Scientists (APECS). In 2016, nearly a third of all researchers at the South Pole were women. The Australian Antarctic Program (AAP) makes a "conscious effort to recruit women."
A social media network has recently been created, "Women in Polar Science". It aims to connect women working in the Arctic and Antarctic sciences and provides them with a platform to share and exchange knowledge, experiences and opportunities.
Sexual harassment and sexism
When heavy equipment operator, Julia Uberuaga, first went to Antarctica in the late 70s and early 80s, she recalled that "the men stared at her, or leered at her, or otherwise let her know she was unwelcome on the job." Rita Matthews, who went to Antarctica during the same period, said that the "men were all over the place. There were some that would never stop going after you." In 1983, Marilyn Woody described living at McMurdo station and said, "It makes your head spin, all this attention from all these men." Then she said, "You realize you can put a bag over your head and they'll still fall in love with you."
Another scientist, Cynthia McFee, had been completely shut out of the "male camaraderie" at her location and had to deal with loneliness for long periods of time. Martha Kane, the second woman to overwinter at the South Pole, experienced "negative pressure" from men with "some viewing her as an interloper who had insinuated herself into a male domain."
In the 1990s, some women experienced stigma in Antarctica. These women were labeled "whores" for interacting with men and those who did not interact with men were called "dykes."
In the late 1990s and early 2000s, women felt that Antarctic operations were "not at all sympathetic to the needs of mothers and that there is a deep concern lest a pregnant woman give birth in Antarctica."
Sexual harassment is still a problem for women working in Antarctica, with many women scientists fielding unwanted sexual advances over and over again. Women continue to be outnumbered in many careers in Antarctica, including fleet operations and trades.
Some organizations, such as the Australian Antarctic Division, have created and adopted policies to combat sexual harassment and discrimination based on gender. The United States Antarctic Program (USAP) encourages women and minorities to apply.
Women record-breakers
Silvia Morella de Palma was the first woman to give birth in Antarctica, delivering Emilio Palma at the Argentine Esperanza base on 7 January 1978.
In 1988 American Lisa Densmore became the first woman to reach the summit Mount Vinson.
In 1993, American Ann Bancroft led the first all woman expedition to the South Pole. Bancroft, and Norwegian Liv Arnesen, were the first women to ski across Antarctica in 2001.
In 2010, the first female chaplain to serve on the continent of Antarctica was Chaplain, Lt Col Laura Adelia of the U.S. Air Force, where she served the people at McMurdo Station.
Maria Leijerstam became the first person to cycle to the South Pole from the edge of the continent in 2013. She cycled on a recumbent tricycle.
Anja Blacha set the record for the longest solo, unsupported, unassisted polar expedition by a woman in 2020.
Honors and awards
In 1975, Eleanor Honnywill became the first woman to be awarded the Fuchs Medal from the British Antarctic Survey (BAS).
The first woman to receive a Polar Medal was Virginia Fiennes, in 1986. She was honored for her work in the Transglobe Expedition. She was also the first woman to "winter in both polar regions."
Denise Allen was the first woman awarded the Australian Antarctic Medal in 1989.
See also
Arctic exploration
European and American voyages of scientific exploration
Farthest South
First women to fly to Antarctica
Heroic Age of Antarctic Exploration
History of Antarctica
List of Antarctic women
List of polar explorers
Timeline of women in Antarctica
Women in science
Women in space
References
Citations
Sources
External links
Women in Antarctica
Guide to the Papers of Elizabeth Chipman
Women in Antarctic science editathons
Scientific Committee on Antarctic Research
Women in Red
Women scientists
People of Antarctica
Women in Antarctica | Women in Antarctica | [
"Technology"
] | 4,820 | [
"Women in science and technology",
"Women scientists"
] |
51,411,486 | https://en.wikipedia.org/wiki/Lucia%20V.%20Streng | Lucia V. Streng (November 6, 1909 – April 28, 1995) was a Russian Empire-born American chemist. She spent much of her career studying the noble gases and their properties, successfully synthesizing krypton difluoride. She and her husband, Alex G. Streng, both held positions at Temple University.
Personal life and education
Streng was among the first women to receive a degree in mining engineering from Donetsk Mining Institute. She was born in the Russian Empire. During World War II she fled the Soviet Union with her husband and son. The family settled in West Germany for several years, then emigrated to the United States in 1950. Lucia Streng earned money painting china lamps until she and her husband found positions at Temple University.
Career
Lucia Streng became a research associate at the Temple University Research Institute several years after her husband, Alex G. Streng, was hired as a research chemist. She performed analytical work for the federal Bureau of Mines as well as private companies. In 1963, Streng reported the successful photochemical synthesis of krypton difluoride, a result that no one else was able to produce until 1975.
Streng published a number of papers, often relating to experimental work with the noble gases krypton and xenon. Her contributions were sometimes noted in a manner less formal than shared authorship: in the acknowledgements of one of Alex Streng's papers, he thanked Lucia and another frequent collaborator, Abraham D. Kirshenbaum, for "their contributions in the experimental work."
Lucia Streng retired from the Research Institute in 1975.
References
1909 births
1995 deaths
Inorganic chemists
Soviet chemists
Temple University faculty
Soviet emigrants to Germany
Emigrants from West Germany to the United States | Lucia V. Streng | [
"Chemistry"
] | 365 | [
"Inorganic chemists"
] |
51,411,681 | https://en.wikipedia.org/wiki/Thomas%20H.%20Lane | Thomas H. Lane is an American organic chemist, and director at Dow Corning Corporation. He served as president of the American Chemical Society in 2009.
Life
He graduated from Purdue University and from Central Michigan University. While working at Dow, he received a PhD from the Open University, of which he is a visiting professor. He is a Fellow of the Royal Society of Chemistry.
He was vice-president at Delta College.
References
American organic chemists
21st-century American chemists
Presidents of the American Chemical Society
Dow Chemical Company employees
Purdue University alumni
Central Michigan University alumni
Alumni of the Open University
Living people
Year of birth missing (living people) | Thomas H. Lane | [
"Chemistry"
] | 129 | [
"Organic chemists",
"American organic chemists"
] |
51,411,849 | https://en.wikipedia.org/wiki/Debbie%20C.%20Crans | Debbie C. Crans is a Professor of Organic, Inorganic and Biological Chemistry and of Cell and Molecular Biology at Colorado State University, where she also is a Professor Laureate of the College of Natural Sciences. Crans specializes in the fundamental chemistry and biochemistry of drugs, with particular focus on vanadium and other transition metal ions as metals in medicine and investigation of their mechanisms of toxicity.
Education
Debbie Crans studied at the University of Copenhagen, studying for her Cand. Scient. 1. part (B.S.) in 1974–1978, then her Cand. Scient. 2. part (research) in 1978–1980. During this time, she worked with Prof. James P. Snyder at Copenhagen, and Prof. Paul von Ragué Schleyer at the University of Erlangen–Nuremberg in Germany on computational studies of free radicals. She then moved to Harvard University in the United States to pursue graduate studies in the laboratory of Prof. George M. Whitesides. At Harvard, Crans worked on enzyme-catalyzed phosphorylation reactions, using glycerol kinase to synthesize chiral analogs of glycerol. She graduated with her Ph.D. in 1985. She went on to do postdoctoral work with Orville L. Chapman and Paul D. Boyer at the University of California, Los Angeles from 1985 to 1986, studying the mechanistic enzymology of the F1 subunit of ATP synthase from chloroplasts and beef heart.
Independent career and research
Crans began her independent career as an assistant professor at Colorado State University in 1987. She was promoted to associate professor in 1991, and full professor in 1998.
Crans is known for her work on the role of vanadium in biological systems, especially the effects of its compounds on diabetes. She has worked as senior editor several books on vanadium, such as Vanadium Compounds: Chemistry, Biochemistry, and Therapeutic Applications, Vanadium: The Versatile Metal and Vanadium in Biochemistry. Crans served as chair of the American Chemical Society in 2015 and 2016. She has also been associate editor for the New Journal of Chemistry, Inorganic Chemistry, the Journal of Inorganic Biochemistry and Coordination Chemistry Reviews.
Crans has contributed to over 215 peer-reviewed articles. As of spring 2019, her work has been cited 7,200 times excluding self-citations making her h-index of 53. Her review paper, "The chemistry and biochemistry of vanadium and the biological activities exerted by vanadium compounds" has been cited over 900 times. Her study on "Effects of vanadium complexes with organic ligands on glucose metabolism: a comparison study in diabetic rats" describes the use of vanadium compounds as hypoglycemic agents, and it has been widely cited.
Awards
International Awards
2019 ACS Award for Distinguished Service in the Advancement of Inorganic Chemistry
2015 Arthur C. Cope Scholar Award
2012 Lectureship award, Japanese Coordination Chemistry Society
2004 Vanadis award from the International Vanadium Symposium in Szeged
2000 Japan Society of Promotion of Science award
2000 Alexander Humboldt Senior Research awardee
National Awards
2017 ChemLuminary Awards Young Chemists Committee
2016 Royal Society Fellow
2014 AAAS Fellow
2009 ACS Fellow
1993-96 Alfred P. Sloan Research Fellow
1994 Alberta Heritage Foundation award
1990-1992 Eli Lilly Young Investigator Award
1989-1994 National Institutes of Health FIRST award
Personal life
She currently resides in Northern Colorado with her husband and three daughters. One daughter is pursuing the PhD in chemistry at Northwestern University, one is an undergraduate student at Colorado State University, and one works as a financial planner.
References
Danish women chemists
American women chemists
Bioinorganic chemists
Harvard University alumni
Danish emigrants to the United States
Living people
Colorado State University faculty
University of Copenhagen alumni
1955 births
Place of birth missing (living people)
American women academics
21st-century American women | Debbie C. Crans | [
"Chemistry"
] | 791 | [
"Bioinorganic chemistry",
"Bioinorganic chemists"
] |
51,411,922 | https://en.wikipedia.org/wiki/Algorithmic%20paradigm | An algorithmic paradigm or algorithm design paradigm is a generic model or framework which underlies the design of a class of algorithms. An algorithmic paradigm is an abstraction higher than the notion of an algorithm, just as an algorithm is an abstraction higher than a computer program.
List of well-known paradigms
General
Backtracking
Branch and bound
Brute-force search
Divide and conquer
Dynamic programming
Greedy algorithm
Recursion
Prune and search
Parameterized complexity
Kernelization
Iterative compression
Computational geometry
Sweep line algorithms
Rotating calipers
Randomized incremental construction
References
Algorithms | Algorithmic paradigm | [
"Mathematics"
] | 112 | [
"Applied mathematics",
"Algorithms",
"Mathematical logic"
] |
51,412,123 | https://en.wikipedia.org/wiki/F420H2DH%20family | The H+-translocating F420H2 Dehydrogenase (F420H2DH) Family (TC# 3.D.9) is a member of the Na+ transporting Mrp superfamily. A single F420H2 dehydrogenase (also referred to as F420H2:quinol oxidoreductase) from the methanogenic archaeon, Methanosarcina mazei Gö1, has been shown to be a redox driven proton pump. The F420H2DH of M. mazei has a molecular size of about 120 kDa and contains Fe-S clusters and FAD. A similar five-subunit enzyme has been isolated from Methanolobus tindarius. The sulfate-reducing Archaeoglobus fulgidus (and several other archaea) also have this enzyme.
Function
Reduction of 2-hydroxyphenazine by F420H2DH is accompanied by the translocation of 1 H+ per 2 electrons transferred.
Transport Reaction
The overall vectorial reaction catalyzed by F420H2DH is
Reduced donor (2e−) + H+ (in) ⇌ oxidized acceptor (2e−) + H+ (out)
Role in Methanogenesis
Methanomassiliicoccus luminyensis has been isolated from the human gut and requires H2 and methanol or methylamines to produce methane. The organism lacks cytochromes, indicating that it cannot couple membrane-bound electron transfer reactions with the extrusion of protons or sodium ions using other known methanogenic pathways. Furthermore, M. luminyensis contains a soluble MvhAGD/HdrABC complex, as found in obligate hydrogenotrophic methanogens, but the energy conserving methyltransferase (MtrA-H) is absent. Evidence has been presented that M. luminyensis uses two types of heterodisulfide reductases (HdrABC and HdrD) in an energy conserving process. RT-qPCR studies revealed that genes coding for both heterodisulfide reductases were expressed at high levels. Other genes with high transcript abundance were fpoA as part of the operon encoding the 'headless' F420H2 dehydrogenase and atpB as part of the operon encoding the A1Ao ATP synthase. High activities of the soluble heterodisulfide reductase HdrABC and the hydrogenase MvhADG were found in the cytoplasm. Also, heterologously produced HdrD could reduce CoM-S-S-CoB using reduced methylviologen as electron donor. It is proposed that membrane-bound electron transfer is based on the conversion of two molecules of methanol and the concurrent formation of two molecules of the heterodisulfide CoM-S-S-CoB. First, the HdrABC/MvhADG complex catalyzes the H2-dependent reduction of CoM-S-S-CoB and the formation of reduced ferredoxin. Second, reduced ferredoxin is oxidized by the 'headless' F420H2 dehydrogenase, thereby translocating up to 4 H+ across the membrane, and electrons are channeled to HdrD for the reduction of the second heterodisulfide.
Homology
The gene cluster encoding the F420H2DH includes 12 genes, fpoABCDHIJKLMNO. Several of the subunits are related to those of the mitochondrial 'complex I' NDH family members (TC# 3.D.1). Thus, the gene products, FpoA, H, J, K, L, M and N, are highly hydrophobic and are homologous to subunits that form the membrane integral module of NDH-1. FpoB, C, D and I have their counterparts in the amphipathic membrane-associated module of NDH-1. However, homologues of the hydrophilic subunits of the NADH-oxidizing complex are absent.
See also
Transporter Classification Database
References
Protein families
Membrane proteins
Transmembrane proteins
Transmembrane transporters
Transport proteins
Integral membrane proteins | F420H2DH family | [
"Biology"
] | 898 | [
"Protein families",
"Protein classification",
"Membrane proteins"
] |
51,412,220 | https://en.wikipedia.org/wiki/Mrp%20superfamily | The Na+ Transporting Mrp Superfamily is a superfamily of integral membrane transport proteins.
It includes the TC families:
2.A.63 - The Monovalent Cation (K+ or Na+):Proton Antiporter-3 (CPA3) Family
3.D.1 - The H+ or Na+-translocating NADH Dehyrogenase (NDH) Family
3.D.9 - The H+-translocating F420H2 Dehydrogenase (F420H2DH) Family
Mrp of Bacillus subtilis is a 7 subunit Na+/H+ antiporter complex (TC# 2.A.63.1.4). All subunits are homologous to the subunits in other members of this monovalent cation (K+ or Na+):proton antiporter-3 (CPA3) family as well as subunits in the archaeal hydrogenases (TC#s 3.D.1.4.1 and 3.D.1.4.2), which share several subunits with NADH dehydrogenase subunits (3.D.1). The largest subunits of the Mrp complex (MrpA and MrpD) are homologous to subunits in NADH dehydrogenases (NDHs): ND2, ND4 and ND5 in the fungal NADH dehydrogenase complex and most other NDHs, as well as subunits in the F420H2 dehydrogenase of Methanosarcina mazei (TC#3.D.9.1.1). These homologous subunits may catalyze Na+/K+ and/or H+ transport.
See also
Transporter Classification Database
References
Protein superfamilies
Membrane proteins
Transmembrane proteins
Transmembrane transporters
Transport proteins
Integral membrane proteins | Mrp superfamily | [
"Biology"
] | 404 | [
"Protein superfamilies",
"Protein classification",
"Membrane proteins"
] |
51,412,320 | https://en.wikipedia.org/wiki/Hasami%20ware | is a type of Japanese pottery produced in the town of Hasami, Higashisonogi-gun, Nagasaki Prefecture. Originally produced for common people, Hasami porcelain has a history of 400 years.
History
In 1599, when the Korean potter Yi Sam-pyeong was brought to Japan after the Japanese Invasion of Korea, climbing kilns and pottery centers developed in Hatanohara, Furusaraya, Yamanita and Hasami under the direction of Ōmura Yoshiaki, daimyo of Ōmura Domain. Typical Hasami ware uses underglaze cobalt blue and celadon, but at first they produced stonewares. Later the materials for porcelain were found, so gradually Hasami ware shifted from pottery to porcelain. In the late Edo period, Hasami was the number one producer of blue-and-white porcelain in Japan, and bottles and other products were exported. As its prices were low, Hasami ware was also distributed widely throughout Japan as everyday items for the common people. Hasami ware was a major source of revenue for Ōmura Domain, where they produced the biggest quantity of porcelain in the country in the latter Edo period.
In the modern period, the kilns in Hasama became subcontractors for Arita ware, and the name gradually became an unknown brand. Concerned that its brand identity would disappear, after 2002 Hasami began promoting its products under the "Hasami ware" label, and to revive the concept of producing "affordable everyday tableware for the masses that suits modern life."
Hizen Hasami Pottery Kiln Sites
The are the ruins of the kilns which produced Hasami Ware in the Edo to early modern period. A total of 36 kiln sites have been identified in eight areas in the hills which surround the town of Hasami. Among them, the oldest, Hatanohara kiln (畑ノ原窯), has a remaining length of 55.4 meters and was one of the largest in Hizen Province during this period. It is a multi-chambered climbing kiln consisting of over 24 kiln rooms. From the early to mid-17th century, the first celadon in Japan was produced at this kiln, and production continued until the early 18th century. The earliest kiln dedicated solely to celadon was the Mimata celadon kiln (三股青磁窯), and the latest was the Nagatayama kiln (長田山窯). This celadon, known as "Hasami Celadon" or "Mimata Celadon," shows the influence of the Longquan kilns in China, and features floral designs created using advanced single-cut carving techniques and a transparent glaze.
In the late 17th century, Chinese porcelain production declined, and Hasami began to produce large quantities of products, mainly for Southeast Asia, but towards the end of the 17th century, exports of Chinese porcelain resumed, and Hizen porcelain shifted to domestic use. From the 18th century onwards, Hasami began to build huge kilns to mass-produce everyday products and reduce costs, a method that continued until the end of the Edo period. The Nakaoue climbing kiln (中尾上登り窯), was over 160 meters long and 33 firing chambers, the Nagaohon climbing kiln (永尾本登り窯), was 155 meters long, and had 29 firing chambers. These five kiln sites were designated collectively as a National Historic Site in 2000, along with the site of the Minmata Toishigawa quarry (三股砥石川陶石採石場) and the site of the Sarayama government office (皿山役所跡).,The Sarayama government office was established by Ōmura domain in 1666 and continued to exist until 1870, and served as the central management center for the Hasami kilns, collecting tax revenue and inspecting product
See also
List of Historic Sites of Japan (Nagasaki)
References
External links
http://www.hasamiyaki.or.jp/
Culture in Nagasaki Prefecture
Japanese pottery
Japanese porcelain
History of Nagasaki Prefecture
Hizen Province
Historic Sites of Japan
Japanese pottery kiln sites | Hasami ware | [
"Chemistry",
"Engineering"
] | 854 | [
"Kilns",
"Japanese pottery kiln sites"
] |
51,413,131 | https://en.wikipedia.org/wiki/Free%20field%20%28acoustics%29 | In acoustics, a free field is a situation or space in which no sound reflections occur.
Characteristics
The lack of reflections in a free field means that any sound in the field is entirely determined by a listener or microphone because it is received through the direct sound of the sound source. This makes the open field a direct sound field. In a free field, sound is attenuated with increased distance according to the inverse-square law.
Examples and uses
In nature, free field conditions occur only when sound reflections from the floor can be ignored, e.g. in new snow in a field, or approximately at good sound-absorbing floors (deciduous, dry sand, etc.) Free field conditions can be artificially produced in anechoic chambers. In particular, free field conditions play a major role in acoustic measurements and sound perception experiments as results are isolated from room reflections.
With voice and sound recordings, one often seeks a condition free from sound reflections similar to a free field, even when during post-processing specifically desired spatial impression will be added, because this is not distorted by any sound reflections of the recording room.
In the simple example shown in Figure 1, a singular sound source emits sound evenly and spherically with no obstructions.
Equations
The sound intensity and pressure level of any point in a free field is calculated below, where r (in meters) is the distance from the source and "where ρ and c are the air density and speed of sound respectively.
To calculate for air pressure, the equation can be written differently:
In order to simplify this equation we can remove elements:
Measuring the sound pressure level at a reference distance (Rm) from the source allows us measure another distance (r) more easily than other methods:
This means that as the distance from the sources doubles, the noise level decreases by 6 dB for each doubling. However if the sound field is not truly free of reflections, a directivity factor Q will help "characterise the directional sound radiation properties of a source."
References
See also
Acoustics
Thought experiments in physics | Free field (acoustics) | [
"Physics"
] | 414 | [
"Classical mechanics",
"Acoustics"
] |
51,415,428 | https://en.wikipedia.org/wiki/Pseudoalleles | Pseudoallelism is a state in which two genes with similar functions are located so close to one another on a chromosome that they are genetically linked. This means that the two genes (pseudoalleles) are nearly always inherited together. Since the two genes have related functions, they may appear to act as a single gene. In rare cases, the two linked pseudoalleles can be separated, or recombined. One hypothesis is that pseudoalleles are formed as a result of gene duplication events, and the duplicated genes can undergo gene evolution to develop new functions.
Characteristic of pseudoalleles:
These are closely linked allele within which crossing over occur.
They affect the same character.
Example:
Red eye colour of Drosophila has different mutants like white and apricot. They affect pigmentation i.e., affect the same character. So, they are allelic. They can undergo recombination, i.e., they are nonallelic.
References
Genetics | Pseudoalleles | [
"Biology"
] | 204 | [
"Genetics"
] |
51,415,447 | https://en.wikipedia.org/wiki/Octobot%20%28robot%29 | Octobot is a proof of concept soft-bodied autonomous robot. The project team included Harvard University faculty members Robert Wood and Jennifer A. Lewis, along with researchers with backgrounds in mechanical engineering, 3D printing, microfluidics, and robotics. Octobot was described in the journal Nature in 2016.
Overview
Octobot is a 3D printed soft-bodied autonomous robot that shaped like a small octopus, and its soft body is made of 3D printed silicone gel. It uses hydrogen peroxide as its main power source and also contains a microfluidic logic circuit. Octobot is said to be able to move on its own without any aid by a battery or an electrical power source. The hydrogen peroxide flows around a network of 3D printed hollows (or freckles) within the body of the robot. Hydrogen peroxide moves over platinum pieces, which causes a chemical reaction. This chemical reaction causes a gas to form creating the main power source for the robot. This phenomenon produces a reaction that inflates and moves the arms, to propel the robot through water.
Design influences
The 3D printed silicone gel body of Octobot is designed to mimic the body of an octopus, and neither one has an internal skeleton. This material is flexible and sturdy, all while being able to move with ease. The Octobot is designed to mimic the movements of an octopus.
The Octobot itself has also inspired new possibilities for technologies. Some scientists think that this new technology could pave the way for advancements in the medical field. The discussion of possibly changing the material that these soft-bodied autonomous robots are made from has also surfaced. The Octobot could be made from biodegradable material instead of 3D printed silicone gel, leading to many advancements in environmental awareness. These soft-bodied autonomous robots also have the possibility to be used in search and rescue missions, leveraging their ability to be very flexible and possibly squeeze through spaces that humans or current robots may not.
References
Further reading
Robotic animals
Robots of the United States
2010s in robotics | Octobot (robot) | [
"Biology"
] | 420 | [
"Animals",
"Robotic animals"
] |
51,416,514 | https://en.wikipedia.org/wiki/MycoWorks | MycoWorks is a biotechnology company based in Emeryville, California that produces leather-like products using a process involving mycelium. The company was founded in 2013 by Philip Ross, Sophia Wang, and Eddie Pavlu.
History
Co-founder and chief technical officer Phil Ross's work with mycelium began before the formation of the company, which has assisted in the company's developments. In 2017, Matthew L. Scullin signed on as chief executive officer. In early 2020, the company raised Series A financing, and later that year, $45 million in Series B financing with Natalie Portman and John Legend participating.
Technology
Fine Mycelium is a patented technology by MycoWorks that attempts to influence cellular structures for increased strength and durability. The company uses the term to refer to both their process and the resulting materials intended for the fashion, footwear, automotive, and decor industry.
Products
Reishi was the first commercially available product from MycoWorks, followed by Reishi Doux, Reishi Natural, and Reishi Pebble in 2023. The product has been used in a number of luxury retail items such as handbags and hats. Commercial-scale manufacturing began in September 2023 at a plant in Union, South Carolina.
See also
References
External links
Companies based in San Francisco
Technology companies based in the San Francisco Bay Area
Biotechnology in the United States
2013 establishments in California
Fungi in cultivation | MycoWorks | [
"Biology"
] | 289 | [
"Biotechnology in the United States",
"Biotechnology by country"
] |
51,417,988 | https://en.wikipedia.org/wiki/Vertically%20aligned%20carbon%20nanotube%20arrays | In materials science, vertically aligned carbon nanotube arrays (VANTAs) are a unique microstructure consisting of carbon nanotubes oriented with their longitudinal axis perpendicular to a substrate surface. These VANTAs effectively preserve and often accentuate the unique anisotropic properties of individual carbon nanotubes and possess a morphology that may be precisely controlled. VANTAs are consequently widely useful in a range of current and potential device applications.
Synthesis
There are a handful of experimental technologies available to align a single or an array of CNTs along a pre-determined orientation. The techniques rely on different mechanisms and therefore are applicable to different situations. These techniques are categorized into two groups pertaining to when the alignment is achieved: (a) in-situ techniques where alignment is achieved during the CNT growth process and (b) ex-situ techniques where CNTs are originally grown in random orientations and alignment is achieved afterwards such as during the device integration process.
Thermal chemical vapor deposition
Growth mechanism
Thermal chemical vapor deposition is a common technique to grow aligned arrays of CNTs. In the CVD process, a hot carbonaceous gas decomposes, *leaving carbon diffuses into or around the catalyst particles*, and then nucleates a graphitic nanotube sidewall at one crystallographic face of the catalyst. The catalyst diameter directly controls the diameter of the nanotubes that are grown. There are two primary growth models for the CVD growth of VANTAs: “tip-growth model” and the “base-growth model.” In the case of the tip-growth model, hydrocarbon decomposes on the top surface of the metal, carbon diffuses down through the metal, and CNT precipitates out across the metal bottom, pushing the whole metal particle off the substrate, and continues to grow until the metal is fully covered with excess carbon and its catalytic activity ceases. In the case of the base-growth model, the initial hydrocarbon decomposition and carbon diffusion take place similar to that in the tip-growth case, but the CNT precipitation emerges out from the metal particle's apex and forms a hemispherical dome, which then extends up in the form of seamless graphitic cylinder. Subsequent hydrocarbon decomposition takes place on the lower peripheral surface of the metal, and as-dissolved carbon diffuses upward. Most thermal CVD processes grow nanotubes by the root or base growth method. The morphology of both the individual CNTs and the CNT array is dictated by various CVD growth parameters, which may be tuned to yield vertically aligned arrays of CNTs with various structures.
Catalyst
The catalyst enables the pyrolysis of carbon and subsequent growth of VANTA. Catalysts are typically metals that have high carbon solubility at high temperatures and that exhibit a high carbon diffusion rate, such as iron (Fe), cobalt (Co), and nickel (Ni). Other transition metals such as copper (Cu), gold (Au), silver (Ag), platinum (Pt), and palladium (Pd) are also reported to catalyze CNT growth from various hydrocarbons but have lower carbon solubility and consequently lower growth rates. Solid organometallocenes such as ferrocene, cobaltocene, nickelocene are also common catalysts. It is found that the temperature and time of the thermal and reduction catalyst pre-treatment steps are crucial variables for optimized nanoparticle distribution with different average diameters, depending on the initial film thickness. For CNT growth by CVD, a sputtered thin film of catalyst (e.g. 1 nm of Fe) is applied. During heating, the film de-wets, creating islands of iron that then nucleate nanotubes. As the iron is mobile, islands can merge if left too long at the growth temperature before initiating nanotube growth. Annealing at the growth temperature reduces the site density #/mm2 and increases the diameter of the nanotubes. As the nanotubes grow from the catalyst islands, the crowding effects and van der Waals forces between other CNTs leave them no choice to grow in any direction but vertically to the substrate.
The height of vertically aligned CNTs varies with catalyst particle spacing as well. Reports have indicated that for vertically aligned arrays of CNT bundles, the CNTs grow longer when there are other CNTs growing near them, indicated by longer CNTs grown on larger catalyst particles or when catalyst particles are spaced close together. Choi et al. reported good morphology and dense distribution of VANTAs grown from Ni nano powders and magnetic fluids mixed in polyvinyl alcohol spin-coated on Si and alumina. Xiong et al. demonstrated that single crystal magnesium oxide (MgO) is a capable substrate for growing VANTAs as long as 2.2 mm when catalyzed with a Fe catalyst.
It has also been demonstrated that applying a monolayer of Mo with a Co catalyst suppressed the broadening of the SWNT diameter distribution in the as-grown VANTA, while both the composition and amount of Co and Mo affected the catalytic activity.
Support
The substrate material, its surface morphology and textural properties greatly affect the resulting VANTA yield. Some examples of commonly used substrates in CVD are quartz, silicon, silicon carbide, silica, alumina, zeolite, CaCO3, and magnesium oxide. Most substrates are coated with an underlayer consisting of 10–20 nm of alumina before depositing the catalyst. This regularizes the dewetting of the catalyst into islands of predictable size, and is a diffusion barrier between the substrate and the metal catalyst.
Li et al. have produced VANTA consisting of Y-shaped carbon nanotubes by the pyrolysis of methane over cobalt- covered magnesium oxide catalyst on branched nanochannel alumina templates.
Qu et al. used a pitch-based carbon fiber as a support for the growth of VANTA using a FePc carbon source. The resulting array propagates radially on the surface of the carbon fiber.
Zhong, et al. demonstrated the direct growth of VANTAs on metallic titanium (Ti) coatings with a Fe/Ti/Fe catalyst sputtered on SiO2/Si wafers.
Alvarez et al. reports the ability to spin-coat an alumoxane solution as a catalyst support for VANTA growths via CVD. After a conventional Fe catalyst was evaporated onto the spin-coated support, the resulting VANTA growth yield was similar to conventional Al2O3 powder supports.
Carbon source
The carbon source for the CVD of VANTAs is most commonly a carbon gas such as methane, ethylene, acetylene, benzene, xylene, or carbon monoxide. Other examples of carbon precursors include cyclohexane, fullerene, methanol, and ethanol. The pyrolysis of these gases into carbon atoms varies based on the decomposition rate at growth temperatures, the carbon content of the gas molecules, and the growth catalyst. Linear hydrocarbons such as methane, ethylene, acetylene, thermally decompose into atomic carbons or linear dimers/trimers of carbon, and generally produce straight and hollow CNTs. On the other hand, cyclic hydrocarbons such as benzene, xylene, cyclohexane, fullerene, produce relatively curved/hunched CNTs with the tube walls often bridged inside.
Aligned arrays of MWNTs have been synthesized through the catalytic decomposition of ferrocene-xylene precursor mixture onto quartz substrates at atmospheric pressure and relatively low temperature (~675 °C).
Eres et al. found that the addition of ferrocene into the gas stream by thermal evaporation concurrently with acetylene enhanced carbon nanotube growth rates and extend the VANTA thickness to 3.25 mm. Ferrocene was introduced into the gas stream by thermal evaporation concurrently with the flow of acetylene.
Qu et al. reported a low-pressure CVD process on a SiO2/Si wafer that produces a VANTA consisting of CNTs with curly entangled ends. During the pyrolytic growth of the VANTAs, the initially formed nanotube segments from the base growth process grew in random directions and formed a randomly entangled nanotube top layer to which the underlying straight nanotube arrays then emerged.
Zhong et al. studied purely thermal CVD process for SWNT forests without an etchant gas, and demonstrated that acetylene is the main growth precursor, and the conversion of any feedstock to C2H2 is of key importance to SWNT VANTA growth. A reactive etchant, such as water, atomic hydrogen, or hydroxyl radicals, can widen the SWNT forest deposition window but is not required in cold-wall reactors at low pressures.
Dasgupta et al. synthesized a free-standing macro-tubular VANTA with a spray pyrolysis of ferrocene-benzene solution in a nitrogen atmosphere, with the optimum condition for the formation of macro-tubular geometry was found to be 950 °C, 50 mg/ml ferrocene in benzene, 1.5 ml/min pumping rate of liquid precursor and 5 lpm of nitrogen gas flow rate.
Temperature
At a too low temperature, the catalyst atoms are not mobile enough to aggregate together into particles to nucleate and grow nanotubes and the catalytic decomposition of the carbon precursor may be too slow for the formation of nanotubes. If the temperature is too high, the catalyst becomes too mobile to form particles small enough to nucleate and grow CNTs. A typical range of growth temperatures amenable to the CVD growth of VANTA is 600–1200 °C. The individual CNT structure is impacted by the growth temperature; a low-temperature CVD (600–900 °C) yields MWCNTs, whereas high-temperature (900–1200 °C) reaction favors SWCNT since they have a higher energy of formation. A critical temperature exists for each CVD system where the growth rate plateaus at a maximum value.
The temperature dependence of the carbon nanotube growth with ferrocene exhibits a steep drop at high substrate temperatures and a loss of vertical alignment at 900 °C.
Zhang et al. conducted VANTA growths on a series of Fe/Mo/vermiculite catalysts and reported that with the increasing growth temperature, the alignment of CNTs intercalated among vermiculites became worse.
Flow assisted growth
A key to high growth yields is a proper introduction of oxidative agents under the gas ambient so that the catalyst particle surfaces remain active for the longest possible period, which is presumably achieved by balancing the competition between amorphous carbon growth and sp2 graphitic crystal formation on the catalyst particles. Oxidants can not only remove or prevent amorphous carbon growth, but may also etch into graphite layers when used at higher than favorable concentrations. Hata et al. reported millimeter-scale vertically aligned 2.5 mm long SWCNTs using the water assisted ethylene CVD process with Fe/Al or aluminum oxide multilayers on Si wafers. It was proposed that controlled supply of steam into the CVD reactor acted as a weak oxidizer and selectively removed amorphous carbon without damaging the growing CNTs.
Field-assisted growth
Since CNTs are all electrically conductive they have a tendency to align with the electric field lines. Various methods have been developed to apply a strong enough electric field during the CNT growth process to achieve uniform alignment of CNTs based on this principle. The orientation of the aligned CNTs is mainly dependent on the length of CNTs and the electric field besides the thermal randomization and van der Waals forces. This technique has been employed to grow VANTAs by positively biasing the substrate during CVD growth.
Another modified approach to grow VANTAs is to control the orientation of ferromagnetic catalysts that have one crystallographic magnetic easy axis. The magnetic easy axis tends to be parallel to the magnetic field. As a result, an applied magnetic force can orient these magnetic catalytic nanoparticles, like catalytic iron nanoparticles and Fe3O4 nanoparticles. Because only a certain nanocrystalline facet of catalytic nanoparticles is catalytically active and the diffusion rate of carbon atoms on the facet is the highest, the CNTs preferentially grow from the certain facet of the catalytic nanoparticles and the grown CNTs are oriented at a certain angle.
Individually addressable nanostructures
Carbon nanotubes can be grown on a modified substrate to allow separate electrical contacts to each nanostructure. This nanotube growth is accomplished by lithographically placing metal traces separated by insulator material, and connecting those traces to individual catalyst sites on the substrate surface. The nanotubes are then grown as normal with CVD and a series of reactions at the catalyst forms a single junction between a nanotube and a metal contact. The nanostructures can then be individually functionalized and their electrical responses measured individually without crosstalk and other bottlenecks that arise from array heterogeneity. This technique, which accomplishes precise placement and configuration of individual nanotubes, unlocks and enhances a wide range of applications for VANTA's: diagnostic testing for many analytes simultaneously, high energy density supercapacitors, field effect transistors, etc.
Plasma enhanced CVD
Growth mechanism
In plasma enhanced CVD (PECVD) processes, DC electric fields, radio-frequency electric fields, or microwaves produce plasmas to primarily lower the synthesis temperature of CNTs. At the same time, an electric field (DC or AC) is also produced over the substrate surface to direct CNT growth propagation. The DC-PECVD process for vertically aligned CNT arrays includes four basic steps: evacuation, heating, plasma generation, and cooling. A typical procedure is conducted at a pressure of 8 Torr in NH3 and at a growth temperature in the range of 450–600 ◦. As soon as the temperature and pressure are stabilized, a DC bias voltage of 450–650 V is applied to the gap between two electrodes to ignite an electrical discharge (plasma) over the sample. The growth time may vary from a couple of minutes to hours depending on the growth rate and desired CNT length. When the end of growth time is reached, the bias voltage is removed immediately to terminate the plasma.
Zhong et al. reported a novel point-arc microwave plasma CVD apparatus employed to SWNTs on Si substrates coated with a sandwich-like nano-layer structure of 0.7 nm Al2O3/0.5 nm Fe/ 5–70 nm Al2O3 by conventional high frequency sputtering. The growth of extremely dense and vertically aligned SWNTs with an almost constant growth rate of 270 mm/h within 40 min at a temperature as low as 600 °C was demonstrated for the first time and the volume density of the as-grown SWNT films is as higher as 66 kg/m3.
Catalyst
The formation of a dense and relatively uniform layer of catalyst nanoparticles is also essential for vertically aligned SWCNT growth vertically aligned SWCNTs using the PECVD method. Amaratunga et al. reported the growth of vertically aligned CNTs using a direct current PECVD technique with a Ni and Co catalyst system. Their results show that the alignment of vertically aligned CNTs depends on the electric field and that the growth rate can be changed depending on the CNT diameter, which reaches a maximum as a function of growth temperature. VANTAs consisting of SWNTs have been grown as long as 0.5 cm.
Zhong et al. reported a novel point-arc microwave plasma CVD apparatus employed to SWNTs on Si substrates coated with a sandwich-like nano-layer structure of 0.7 nm Al2O3/0.5 nm Fe/ 5–70 nm AlO by conventional high frequency sputtering. The growth of extremely dense and vertically aligned SWNTs with an almost constant growth rate of 270 mm/h within 40 min at a temperature as low as 600 °C was demonstrated for the first time and the volume density of the as-grown SWNT films is as higher as 66 kg/m.
Support
For PECVD processes, the substrate must be chemically stable under the plasma which is rich of H-species. Some weakly bonded oxides such as indium oxide can be quickly reduced in this plasma and is therefore usually not applicable as the substrate or underlayer. The substrate must also be electrically conductive to sustain a continuous DC current flow through its surface where the CNTs grow from. Most metals and semiconductors are very good substrate materials, and insulating substrates can be first coated with a conductive layer to work properly to support PECVD VANTA growth.
Carbon source
C2H2 is typically introduced to trigger the CNT growth during PECVD of VANTAs. The flow rate ratio of NH3:C2H2 is usually around 4:1 to minimize the amorphous carbon formation. Behr et al. studied the effect of hydrogen on the catalyst nanoparticles during the PECVD of VANTAs, and demonstrated that at H2-to-CH4 ratios of about 1 iron catalyst nanoparticles are converted to Fe3C and well-graphitized nanotubes grow from elongated Fe3C crystals. H2-to-CH4 ratios greater than 5 in the feed gas result in high hydrogen concentrations in the plasma and strongly reducing conditions, which prevents the conversion of Fe to Fe3C and cause poorly-graphitized nanofibers to grow with thick walls.
Temperature
One of the major advantages of using PECVD growth techniques is the low growth temperature. The ionization of the neutral hydrocarbon molecules inside the plasma facilitates the breaking of the C–H bonds and lowers the activation energy of the CNT growth to be about 0.3 eV as opposed to the 1.2 eV needed for thermal CVD processes.
Electrophoretic deposition
CNT solutions can form VANTAs through alignment along DC or AC electric field lines. The CNTs are polarized in the suspension by the electric field because of dielectric mismatch between CNTs and the liquid. The polarization moment rotates the CNTs toward the direction of electric field lines, therefore aligning them in a common direction. After being aligned, the CNTs are taken out with the substrates and dried to form functional VANTAs.
Mechanical strain
Randomly oriented CNTs on a substrate can be stretched to straighten and detangle the film by breaking the substrate and pulling the ends apart. The aligned CNTs are parallel to each other and perpendicular to the crack. The stretching method can macroscopically align the CNTs while not providing deterministic control over individual CNT alignment or position during assembly.
Current applications
Field-emission devices
CNTs have high aspect ratios (length divided by diameter) and induce very high local electric field intensities around the tips. Field emission in solids occurs in intense electric fields and is strongly dependent on the work function of the emitting material. In a parallel-plate arrangement, the macroscopic field Emacro between the plates is given by Emacro = V/d, where d is the plate separation and V the applied voltage. If a sharp object is created on a plate, then the local field Elocal at its apex is greater than Emacro and can be related to:
Elocal=γ×Emacro
The parameter γ is called the field-enhancement factor and basically determined by the shape of the object. Typical field-enhancement factors ranging from 30,000 to 50,000 can be obtained from individual CNTs, therefore making VANTAs one of the best electron-emitting materials.
Blackbody absorber
VANTAs offer a unique light absorbing surface due to their extremely low index of refraction and the nanoscale surface roughness of the aligned CNTs. Yang et al. demonstrated that low-density VANTAs exhibit an ultralow diffuse reflectance of 1 × 10–7 with a corresponding integrated total reflectance of 0.045%. Although VANTA black coatings must be directly transferred or grown on substrates, unlike black coatings consisting of random networks of CNTs that may be processed into CNT paints, they are the considered the blackest man-made material on earth.
VANTA blackbody absorbers are thus useful as stray light absorbers to improve the resolution of sensitive spectroscopes, telescopes, microscopes, and optical sensing devices. Several commercial optical black coating products such as Vantablack and adVANTA nanotube optical blacks have been produced from VANTA coatings. VANTA absorbers may also increase the absorption of heat in materials used in concentrated solar power technology, as well as military applications such as thermal camouflage. Visual displays of VANTA absorbers have generated interest by artists as well seeking to benefit from the quenching of shadows from rough surface. Recently, Vantablack was used by artist Asif Khan to create the Hyundai Pavilion in Pyeongchang for the 2018 Winter Olympics.
Carbon fiber ropes
VANTAs can be processed through volatile solutions or twisted to condense into spun CNT yarns or ropes. Jiang et al. demonstrated a spinning and twisting method that forms a CNT yarn from a VANTA that gives rise to both a round cross-section and a tensile strength of around 1 GPa. The tensile strengths of CNT yarns spun from ultra-long CNT arrays of 1 mm height can range from 1.35 to 3.3 GPa.
Unidirectional Sheets
Lui et al. describe ways to control the physical properties of sheets spun from CNT arrays, including catalyst film thickness, to control tube diameter distribution and growth time to control tube length. These properties can be used to control the electrical and optical properties of the sheet spun from the array. The sheets may be useful in scientific applications, such as the polarization of light through the sheet (the degree of polarization can also be controlled by the temperature of the sheet).
Adhesive films
Biomimicry studies directed towards replicating the adhesion of gecko feet on smooth surfaces have reported success utilizing VANTA as a dry adhesive film. Qu et al. was able to demonstrate VANTA films that exhibited macroscopic adhesive forces of ~100 newtons per square centimeter, which is almost 10 times that of a gecko foot. This was achieved by tuning the growth conditions of the VANTA to form curls at the end of the CNTs, which provide stronger interfacial interactions even with a smooth surface. Qu et al. also demonstrated that the adhesive properties were less temperature sensitive than superglue and scotch tape.
Gas sensor
VANTAs allow the development of novel sensors and/or sensor chips without the need for direct manipulation of individual nanotubes. The aligned nanotube structure further provides a large well-defined surface area and the capacity for modifying the carbon nanotube surface with various transduction materials to effectively enhance the sensitivity and to broaden the scope of analytes to be detected. Wei et al. reported a gas sensor fabricated by partially covering a VANTA with a polymer coating top-down along their tube length by depositing a droplet of polymer solution (e.g., poly(vinyl acetate), PVAc, polyisoprene, PI) onto the nanotube film, inverting the composite film as a free-standing film, and then sputter-coating two strip electrodes of gold across the nanotube arrays that were protruding from the polymer matrix. The flexible VANTA device was demonstrated to successfully sense chemical vapors through monitoring conductivity changes caused by the charge-transfer interaction with gas molecules and/or the inter-tube distance changes induced by polymer swelling via gas absorption. To date, CNTs have shown sensitivities toward gases such as NH3, NO2, H2, C2H4, CO, SO2, H2S, and O2.
Biological sensor
VANTAs act as forests of molecular wires to allow electrical communication between the underlying electrode and a biological entity. The main advantages of VANTAs are the nanosize of the CNT-sensing element and the corresponding small amount of material required for a detectable response. The well-aligned CNT arrays have been employed to work as ribonucleic acid (RNA) sensors, enzymes sensors, DNA sensors, and even protein sensors. Similar VANTAs of MWNTs, grown on platinum substrates, are useful for amperometric electrodes where the oxygenated or functionalized open-ends of nanotubes are used for the immobilization of biological species, while the platinum substrate provides the signal transduction. To increase the selectivity and sensitivity of amperometric biosensors, artificial mediators and permselective coatings are often used in the biosensor fabrication. Artificial mediators are used to shuttle electrons between the enzyme and the electrode to allow operation at low potentials.
Gooding et al. demonstrated that shortened SWNTs can be aligned normal to an electrode by self-assembly and act as molecular wires to allow electrical communication between the underlying electrode and redox proteins covalently attached to the ends of the SWNTs. The high rate of electron transfer through the nanotubes to redox proteins is clearly demonstrated by the similarity in the rate constant for electron transfer to MP-11 regardless of whether SWNTs are present or not.
Thermal interface materials
VANTA interfaces are more thermally conductive than conventional thermal interface materials at the same temperatures because phonons propagate easily along the highly thermally conductive CNTs and thus heat is transported in one direction along the alignment of the CNTs. The distribution and alignment of the thermally conductive CNT fillers are important factors to affect the phonon transport. Huang et al. demonstrated a thermally conductive composite shows an enhancement of 0.65W/m/K with a 0.3wt% loading of VANTA, whereas the enhanced thermal conductivity of a composite with of 0.3 wt% loading of randomly dispersed CNT is below 0.05W/m/K. Tong et al. reported that CNT arrays can be used effectively as thermal interface materials (TIM) due to their high conductance, which they report as ~10^5 W/m^2/K. Thermal interface materials are materials that can enhance thermal conduction at surfaces by having high thermal conductivities; it is useful to have materials which can be designed to fit any geometry. Additionally, the geometry of VANTA systems allows for anisotropic heat transfer. Ivanov et al. found that anisotropic heat transfer could be achieved with VANTAs: they achieved thermal diffusivities up to 2.10.2 cm^2/s, anisotropy ratios up to 72, and found thermal conductivities greater than those of materials used in microelectronics today. Heat transfer properties rely heavily on the structure of the array, so the methods used to manufacture the product must be uniform and reproducible for widespread use. Defects in the structure can also drastically disrupt the heat transfer properties of the material.
Solar cells
Vertically aligned periodic arrays of carbon nanotubes (CNTs) are used to create topographically enhanced light-trapping photovoltaic cells. The CNTs form the back contact of the device and serve as a scaffold to support the photoactive heterojunction. Molecular beam epitaxy is used to deposit CdTe and CdS as the p/n-type materials and ion-assisted deposition is used to deposit a conformal coating of indium-tin oxide as the transparent top contact. Photocurrent produced “per cm2 of footprint” for the CNT-based device is 63 times that of a commercially available planar single crystal silicon device.
Transistors
VANTAs of SWNTs with perfectly linear geometries are applicable as high-performance p- and n-channel transistors and unipolar and complementary logic gates. The excellent properties of the devices derive directly from a complete absence, to within experimental uncertainties, of any defects in the arrays, as defined by tubes or segments of tubes that are misaligned or have nonlinear shapes. The large number of SWNTs enables excellent device-level performance characteristics and good device-to-device uniformity, even with SWNTs that are electronically heterogeneous. Measurements on p- and n-channel transistors that involve as many as about 2,100 SWNTs reveal device-level mobilities and scaled transconductance approaching about 1,000 cm2 V-1 s-1 and $3,000 S m-1, respectively, and with current outputs of up to about 1 A in devices that use interdigitated electrodes.
Low-dielectric material
The low κ materials with low relative dielectric constants are employed as the insulating layers in integrated circuits to reduce the coupling capacitance. The relative dielectric constant of electrically insulating layers can be reduced further by introducing cavities into the low-κ materials. If elongated and oriented pores are used, it is possible to reduce significantly the effective κ value without increasing the proportion of the cavity volume in a dielectric. The CNTs in VANTAs have a high aspect ratio and can be used to introduce elongated, oriented pores into a low-κ dielectric to further reduce the effective κ value of the dielectric.
Catalyst support
Palladium supported on vertically aligned multi-walled carbon nanotubes (Pd/VA-CNTs) is used as catalyst for the C-C coupling reactions of p-iodonitrobenzene with styrene and ethyl acrylate under microwave irradiation. Pd/VA-CNTs catalyst exhibits higher activity compared to Pd supported on activated charcoal, under the same reaction conditions. Due to the microwave irradiation, the kinetics of the reaction are strongly accelerated compared to that obtained with a traditional heating mode. The macroscopic form of aligned CNTs support allows an easy recovery of the catalyst, avoiding costly post-reaction separation processes. In addition, the interaction between the active phase and the support leads to negligible leaching of palladium during recycling tests. The observed results indicate that Pd/CNTs is a recyclable and stable heterogeneous catalytic system.
Fuel cell
Fuel cells are made up of three sandwiched segments: an anode, an electrolyte, and a cathode, in a reaction cell where electricity is produced inside the fuel cells through the reactions between an external fuel and an oxidant in the presence of an electrolyte. The anode hosts a catalyst that oxidizes the fuel, turning the fuel into positively charged ions and negatively charged electrons. This fuel is typically hydrogen, hydrocarbons, and alcohols. The electrolyte blocks the transportation of electrons while conducting ions. The ions traveling through the electrolyte are re-united on the cathode with the electrons passing through a load during a reaction with an oxidant to produce water or carbon dioxide. Ideal anode supports for the deposition of catalytic nanoparticles are porous conductive materials to maximize the electrocatalytic activity. VANTAs are therefore ideal materials due to their intrinsic high conductivity, high surface area, and stability in most fuel cell electrolytes. A typical catalyst deposited on VANTA anodes is platinum, which can be electrodeposited on the individual CNTs of the VANTA. The electrocatalytic activity at the anode is optimal when the Pt particles are uniformly dispersed within the VANTA.
Gong et al. reported that VANTAs doped with nitrogen can act as a metal-free electrode with a much better electrocatalytic activity, long-term operation stability, and tolerance to crossover effect than platinum for oxygen reduction in alkaline fuel cells. In air-saturated 0.1 molar potassium hydroxide, a steady-state output potential of –80 millivolts and a current density of 4.1 milliamps per square centimeter at –0.22 volts was observed, as compared to –85 millivolts and 1.1 milliamps per square centimeter at –0.20 volts for a platinum-carbon electrode. The incorporation of electron-accepting nitrogen atoms in the conjugated nanotube carbon plane appears to impart a relatively high positive charge density on adjacent carbon atoms. This effect, coupled with aligning the nitrogen-doped CNTs, provides a four-electron pathway for the oxygen reduction reactions on VANTAs with a superb performance.
Supercapacitors
Like ordinary capacitors, VANTA supercapacitors and electromechanical actuators typically comprise two electrodes separated by an electronically insulating material, which is ionically conducting in electrochemical devices. The capacitance for an ordinary planar sheet capacitor inversely depends on the inter-electrode separation. In contrast, the capacitance for an electrochemical device depends on the separation between the charge on the electrode and the countercharge in the electrolyte. Because this separation is about a nanometer for CNTs in VANTA electrodes, as compared with the micrometer or larger separations in ordinary dielectric capacitors, very large capacitances result from the high CNT surface area accessible to the electrolyte. These capacitances (typically 15–200 F/g, depending on the surface area of the nanotube array) result in large amounts of charge injection when only a few volts are applied.
Futaba et al. reported a technique to form super-capacitors from a VANTA flattened by settling the erect CNTs by wetting them with a liquid. The capacitance of the SWNT solid EDLC was estimated as 20 F g−1 from the discharge curves of cells charged at 2.5V for a two-electrode cell, and corresponds to 80 F g−1 for a three-electrode cell. The energy density (W = CV2/2) was estimated to be 69.4 W h kg−1 (from 80 F g−1) when normalized to the single electrode weight.
In Pitkänen et al., on-chip energy storage is demonstrated using architectures of highly aligned vertical carbon nanotubes acting as supercapacitors, capable of providing large device capacitances. The efficiency of these structures is further increased by incorporating electrochemically active nanoparticles such as MnOx to form pseudocapacitive architectures thus enhancing areal specific capacitance to 37 mF/cm2.
Batteries
Unlike in ultracapacitors where the solvent of the electrolyte is not involved in the charge storage mechanism, the solvent of the electrolyte contributes to the solid–electrolyte interphase in batteries. The Li-ion batteries usually consist of an active carbon anode, a lithium–cobalt oxide cathode, and an organic electrolyte. In order to obtain better electrode performance than networks of random CNTs and CNT composites, VANTAs are used as to provide better electron transport and higher surface area.
Nanostructured materials are gaining increased attention because of their potential to mitigate current electrode limitations. However, it is possible to use of vertically aligned multi-walled carbon nanotubes (VA-MWNTs) as the active electrode material in lithium-ion batteries. At low specific currents, these VA-MWNTs have shown high reversible specific capacities (up to 782 mAh g−1 at 57 mA g−1). This value is twice that of the theoretical maximum for graphite and ten times more than their non-aligned equivalent. Interestingly, at very high discharge rates, the VA-MWNT electrodes retain a moderate specific capacity due to their aligned nature (166 mAh g−1 at 26 A g−1). These results suggest that VA-MWNTs are good candidates for lithium-ion battery electrodes which require high rate capability and capacity.
Future potential
Space Elevator
Owing to the high tensile strength and large aspect ratio of carbon nanotubes, VANTAs are a potential tether material for the Space Elevator concept.
Silicon replacement in next generation transistors
Carbon nanotubes have much higher carrier mobility than silicon and thus can be much faster and more energy efficient when used in electronics as a silicon replacement.
Challenges obstructing commercialization
There are three main issues preventing broader-scale carbon nanotube-based technology commercialization: Separating metallic and semiconducting nanotubes, high junction resistance due to very small contact area, and placing the nanotubes exactly (nanometer resolution) where they need to go in the circuit. There has been a great deal of work in reducing the contact resistance in carbon nanotube devices. Researchers at UC Berkeley found that adding an interfacial graphite layer during synthesis decreased junction resistance. Researchers at IBM Watson have also attached chemical scaffolds at the base contact point of the nanotube, to a similar effect.
References
Carbon nanotubes
Refractory materials | Vertically aligned carbon nanotube arrays | [
"Physics"
] | 7,666 | [
"Refractory materials",
"Materials",
"Matter"
] |
51,418,538 | https://en.wikipedia.org/wiki/Immuno-psychiatry | Immuno-psychiatry, according to Pariante, is a discipline that studies the connection between the brain and the immune system. It differs from psychoneuroimmunology by postulating that behaviors and emotions are governed by peripheral immune mechanisms. Depression, for instance, is seen as malfunctioning of the immune system.
History
History Tying The Immune System to Psychosis
Since the late 1800’s scientists and physicians have noticed a possible link between the immune system and psychiatric disorders. In 1876 Alexandar Rosenblum, and later in the 1880s Dr. Julius Wagner-Jauregg, observe patients with neurosyphilis, syphilis that had spread to the nervous system, have decreased symptoms of psychosis after contracting malaria. Then from the 1920s, Karl Menninger notices how many patients recovering or recovered from influenza have psychosis similar to that seen in patients with schizophrenia. Moritz Tramer then reports how schizophrenia is associated with a child being born in the winter or spring months (when influenza is most commonly contracted). Later in 1980s, much research is conducted associating increased rates of schizophrenia in patients with a history of prenatal, postnatal infection, and especially childhood central nervous system infections.
History: Tying Inflammatory States to Changes in Mood
In modern medicine, William Osler provides an early documentation of the association between inflammation and changes in mood and motivation. In his 1892 book, "The Principles and Practice of Medicine," he observed that clinical patients with progressive septicemia showed "early delirium and marked mental prostration and apathy."
In 1988 while studying animals, Benjamin Hart coined the term "sickness behavior" to describe the "sleepy or depressed or inactive" state and decreased motivation to move about that sick animals displayed. A previous study from 1979, by M.J. Murry, found increased mortality when animals were force-fed after reducing their food intake in response to bacterial infection, suggesting that these changes played an essential role in fighting off infection.
Beginning in the mid 1990s, investigation into the similarity in these animal “sick behavior” and persons with depression led to more and more studies showing elevated levels of pro-inflammatory cytokines among persons with depression. Many of these early studies in sickness behavior showed significant differences in the many pro-inflammatory cytokines reviving interest into the role that the immune system played in psychiatric disorders.
Modern immuno-psychiatry model
Modern immuno-psychiatry theory now focuses on some variation of this model of how the environment leads to biological changes which affect the peripheral immune system and later affect the mind, mood, behavior, and response to psychiatric treatment. Stress leads to processing by the sympathetic nervous system which releases catecholamines (dopamine and norepinephrine) that increase the number of monocytes, which respond to inflammatory signals (DAMPS/MAMPs), which causes the release of pro-inflammatory cytokines, which then later reach the brain and lead to changes in neurotransmitter metabolism neuronal signaling, and ultimately behavior.
Support For The Role of The Immune System Affecting Mood and Behavior
How Cytokines Can Reach The Brain And Central Nervous System
Passing through more leaky areas of the blood brain barrier, near the circumventricular organs.
Active transport of cytokines in the blood to bypass the Blood Brain Barrier.
Activation of endothelial cells lining the brain's vasculature which later release cytokines into the central nervous system.
Cytokines binding receptors on peripheral afferent nerves which then conduct a message to the central nervous system in specialized regions of the brain which release their own cytokines.
Recruitment of monocytes in the blood which then travel to the brain and release cytokines.
How Cytokines Can Cause Changes To Neurotransmitter levels Which Can Sometimes Be Reversed.
Pro-inflammatory cytokines alter the metabolism of neurotransmitters and has been documented to effect decrease levels of serotonin, increase indolamine-2,3-dioxygenase (IDO) activity(which normally catabolizes tryptophan and consequentially decrease serotonin synthesis), increased levels of kynurenine (leading to decreased glutamate and dopamine release), decrease dopamine as well as decreased levels of expression of tyrosine hydroxylase (which is required to make dopamine), increased levels of quinolinic acid, leading to more NMDA receptor activation and oxidative stress leading to excitotoxicity and neurodegeneration.
Additionally, cytokines interferon-alpha and IL-6 can cause reversible reductions in brain levels of tetrahydrobiopterin (used in the serotonin, dopamine, and norepinephrine synthesis pathways). However, inhibition of nitric oxide synthase, one of the down stream effects of interferon-alpha, can lead to a reversal of this decrease in tetrahydrobiopterin.
How Cytokines Can Cause Molecular And Cellular Changes Similar to Those Seen In Patients With Mood Disorders
Microglia make the most cytokines of all cells in the brain, respond to stress, and are likely important in the stress response as they are found to be increased in density (yet decreased in overall number) in different parts of the brain of persons who had killed themselves with major depressive disorder, bipolar disorder, and schizophrenia.
On a molecular level, cytokines effect the glutamate metabolism of the nervous system and can lead to structural changes involving microglia similar to those seen in depressed patients. TNF-alpha and IL-1, through oxidative stress via increased release of reactive oxygen and nitrogen species, impair re-uptake and transport of glutamate by glial cells, increasing release of glutamate by astrocytes and microglia, leading to an excitotoxic state. This loss of oligodendrocytes (the astrocytes and microglia mentioned before) are a key marker in structural analysis of the brains of depressed patient populations.
How Inflammatory Cytokines Can Disrupt Cortisol Signaling And The HPA-axis Seen in Psychopathologies
The hippocampus helps regulate the HPA-axis' secretion of cortisol and has the largest number of glucocorticoid receptors in the brain. This makes it making it especially sensitive to stress and stress related increases to cortisol. Additionally, the neuroendocrine response by the HPA-axis is effected by the regulation of glucocorticoid receptor expression in the different regions of the brain. And multiple studies have shown that “altered HPA stress responsivity being associated with increased risk of psychopathology” such as in the study of human brain cell, gathered post-mortem, mRNA was harvested in patients who had killed themselves with either a history or a lack of a history of early childhood stresses revealed significant epigenetic changes in glucocorticoid receptor expression.
Patients with elevated levels chronic inflammatory cytokines, (such as those with chronic hepatitis C and others undergoing injections of interferon-alpha, cause changes in glucocorticoid receptors and cortisol release similar to patients with major depression. Both exhibit a loss of the normal cortisol rhythm of secretion throughout the day, and both show a loss of functional glucocorticoid receptors which would otherwise decrease the inflammation in the body.
Associated findings in Major Depressive Disorder
Following studies of patients with significant chronic inflammation, like those undergoing interferon-alpha therapy for hepatitis C showing an association with depressive symptoms, not unlike Osler's "sickness behavior", more studies into major depressive disorder and its link to inflammation have been done. There have been many studies inferring a link between inflammation and major depressive disorder from correlating levels of cytokines in the blood, correlating genes linked to inflammation to treatment response, and changes in cytokines to antidepressant therapy.
Many studies investigating the role of the immune system in patients with major depressive disorder found that such patients had decreased immune cell activity of natural killer cells and lymphocytes despite reliably having elevated levels of pro-inflammatory cytokines(IL-6, TNF-alpha, and C-reactive protein). Depression is also associated with a decrease in regulatory T cells which secrete anti-inflammatory IL-10 and TGF-beta. Different studies have shown the that persons with depression also have lower circulating levels of IL-10, TGF-beta, in addition to the mentioned elevated levels of pro-inflammatory IL-6 in their blood stream.
Antidepressants have been used to infer a link between inflammation and major depressive disorder. In human studies associating the link between inflammation and depression found that giving antidepressants prior to an expected inflammatory insult decreased observed severity of depression. For example, giving paroxetine prior to treatment for malignant melanoma and hepatitis C was found to decrease depressive symptoms compared to persons not given paroxetine (an antidepressant). Additional experimental support of giving an antidepressant prior to injection of endotoxin, a substance known to cause systemic inflammation) was also found to reduce self-reported symptoms of depression. In studies of antidepressant use, some persons show return to normal cytokine levels with depression treatment. Patients with major depressive disorder treated with antidepressants have an increase in regulatory T cells and a decrease in inflammatory IL-1 beta. And even more strongly replicated, patients with increased levels of pro-inflammatory cytokines, or even genes tied to increased pro-inflammatory activity, are more likely to have antidepressant resistant depression.
Through all these studies there seems to be a slight difference in symptoms of major depressive disorder with and without inflammation. Inflammation related depression tends to have less guilt/self negativity and increased slowness and lack of appetite compared to depression in persons without increased levels of systemic inflammation.
Proposed roles of the immune system in Schizophrenia and Psychotic Disorders
There are ties to episodes of psychosis, and persons at risk for schizophrenia, severity of schizophrenia, and with antipsychotic therapy especially with levels of IL-6 in the blood as well as the cerebrospinal fluid of patients with schizophrenia.
Following studies revealing kynurenic acid's uniqueness as being the NMDA receptor's only endogenous (naturally found in the body) antagonist, and the fact that psychosis can be elicited from NMDA receptor antagonism, multiple studies investigated and confirmed change levels of this kynurenic acid may be related to psychosis. Later drug studies have found that COX1 inhibition, which increases kynurenic acid, has been reported to cause psychotic symptoms. COX2 selective inhibitors like celecoxib, which reduce kynurenic acid, were found to reduce clinical severity of schizophrenia in non-randomized, unblinded clinical trials. While encouraging, these results remain to be confirmed in randomized clinical trials with confirmatory results before they are even considered for off-label usage.
Recent research has shown that patients with OCD have six times the amount of a protein called Immuno-moodulin, or Imood, compared to individuals who do not contend with OCD. In addition to OCD, Imood was also found to increase symptoms of anxiety and stress, both mental health areas that have already been linked to OCD.
Overall impact for clinical medicine
The overall results for the many clinical trials of combinations of NSAIDS and antidepressants, proposed to more thoroughly treat standard major depressive disorder and treatment-resistant major depressive disorder, shows that the current degree of importance of addressing the inflammatory component of mood disorders is unclear. Mixed results of some or no improvement in such studies, and the relative lack of studies recruiting sufficient numbers of patients with treatment resistant depression, a lack of studies of patients with chronic inflammation and treatment depression, and a lack of a standardized definition of an elevated chronic inflammatory state leaves more studies to be desired in pursuing the understanding of inflammation and psychiatric disorders.
References
Immunology
Psychiatric assessment | Immuno-psychiatry | [
"Biology"
] | 2,520 | [
"Immunology"
] |
68,522,460 | https://en.wikipedia.org/wiki/Table%20extraction | Table extraction is the process of recognizing and separating a table from a large document, possibly also recognizing individual rows, columns or elements.
It may be regarded as a special form of information extraction.
Table extractions from webpages can take advantage of the special HTML elements that exist for tables, e.g., the "table" tag,
and programming libraries may implement table extraction from webpages.
The Python pandas software library can extract tables from HTML webpages via its read_html() function.
More challenging is table extraction from PDFs or scanned images, where there usually is no table-specific machine readable markup.
Systems that extract data from tables in scientific PDFs have been described.
Wikipedia presents some of its information in tables,
and, e.g., 3.5 million tables can be extracted from the English Wikipedia.
Some of the tables have a specific format, e.g., the so-called infoboxes.
Large-scale table extraction of Wikipedia infoboxes forms one of the sources for DBpedia.
Commercial web services for table extraction exist, e.g., Amazon Textract, Google's Document AI, IBM Watson Discovery, and Microsoft Form Recognizer.
Open source tools also exist, e.g., PDFFigures 2.0 that has been used in Semantic Scholar.
In a comparison published in 2017, the researchers found the proprietary program ABBYY FineReader to yield the best PDF table extraction performance among six different tools evaluated. In a 2023 benchmark evaluation, Adobe Extract, a cloud-based API that employs Adobe’s Sensei AI-platform, performed best among five tools evaluated for table extraction.
References
Natural language processing | Table extraction | [
"Technology"
] | 350 | [
"Natural language processing",
"Natural language and computing"
] |
68,523,328 | https://en.wikipedia.org/wiki/List%20of%20Star%2B%20original%20programming | Star+ (stylised as ST★R+) was a video-on-demand service from The Walt Disney Company launched in Latin America on August 31, 2021. Star+ also produced original local content which was exclusively released on the platform. It was announced that all Star+ content would be integrated into the Star hub on Disney+ starting June 26, 2024, while the standalone app Star+ was discontinued on July 24, 2024.
Original programming
Star+ Originals
Drama
Comedy
Unscripted
Docuseries
Reality
Variety
Co-productions
Continuations
Exclusive international distribution
Exclusive programming
Drama
English
French
Indonesian
Japanese
Korean
Spanish
Turkish
Other
Comedy
English
French
Korean
Other
Adult animation
Anime
Unscripted
Docuseries
Reality
Variety
Continuations
Exclusive films
Notes
References
Internet-related lists
Lists of television series by network
Lists of television series by streaming service
Television lists
Original programming | List of Star+ original programming | [
"Technology"
] | 169 | [
"Computing-related lists",
"Internet-related lists"
] |
68,523,675 | https://en.wikipedia.org/wiki/HD%2025291 | HD 25291, also known as HR 1242, is a solitary, yellowish-white hued star located in the northern circumpolar constellation Camelopardalis. It has an apparent magnitude of 5.12, making it one of the brighter members of this generally faint constellation. The object is relatively far at a distant of approximately 2,100 light years but is drifting closer with a heliocentric radial velocity of .
HD 25291 has a general stellar classification of F0 II, which indicates that it is an evolved early F-type bright giant. It has also been given a class of F2 Ia, instead suggesting a slightly cooler and more luminous supergiant. Nevertheless, it has 8.8 times the mass of the Sun but at an age of 32 million years, it has expanded to 50.1 times its girth. It radiates at a bolometric luminosity 9,878 times greather that of the Sun from its enlarged photosphere at an effective temperature of . HD 25291 is slightly metal deficient, with an iron abundance 85% of solar levels. It spins modestly with a projected rotational velocity of .
Tetzlaff et al. (2011) found the object to be a runaway star with a peculiar velocity of , which is high compared to neighboring stars.
References
025291
1242
Camelopardalis
019018
Durchmusterung objects
F-type bright giants | HD 25291 | [
"Astronomy"
] | 299 | [
"Camelopardalis",
"Constellations"
] |
68,524,399 | https://en.wikipedia.org/wiki/Marihuana%20prensada | Marihuana prensada or cannabis prensado (pressed cannabis or marijuana), also known as ladrillo (brick weed) or, colloquially, paragua or paraguayo is a compressed cannabis cut into blocks that facilitate transport.
The largest producer of pressed marijuana is Paraguay, and from there it is exported to Chile, Bolivia, Brazil, Peru, Colombia, Venezuela, and the United States.
Other names for this product are soko, doko, paraplex macoña, pasto, faso, chamico, enramao, presso, paragua or Paraguayan brick.
Production
In Paraguay, cannabis cultivation occurs mainly in the departments of Alto Paraná, Amambay, Caaguazú, Caazapá, Canindeyú, Concepción, Itapúa and San Pedro. To make pressed bricks, marijuana is harvested, allowed to dry, and compressed in a hydraulic press.
Adulterated brick weed
Sometimes brick weed is adulterated with other binding substances including industrial glues such as Neoprene, tar, ammonia, bitumen, petroleum-derived hydrocarbons, dog food or even human or animal excrement. to make it cheaper, thus being of poorer quality. Its use is strongly discouraged due to the contamination and toxicity of adulterants.
Low quality cannabis
People involved in the production of pressed marijuana often have little or no knowledge about cannabis cultivation, so, during the process, large amounts of trichomes (the most psychoactive part) are wasted, while leaves, stems and seeds are included, which should be avoided. Little care is taken when the branches are left in the sun to dry them; As they are stacked on top of each other, moisture is retained and certain parts begin to rot, parts that will be negligently incorporated into the final product. In some cases, marihuana prensada contains no marijuana, but grass.
Despite its poor quality, its use is widely spread among the lower classes throughout South America.
Use
Although cannabis can be found in foods, beverages, cosmetics, etc., marihuana prensada is exclusively smoked in the form of a cigarette (joint).
Health risks
Marihuana prensada is the most harmful derivative of marijuana, being more toxic than natural marijuana. It is difficult to determine the effects on the human body because its ingredients vary greatly depending on who makes it. In addition, at customs crossings at international borders, it is remixed with other products to mask the smell of cannabis.
The combustion of petroleum and mineral tar increases the risk of cancer in the respiratory tract. Neoprene, a glue considered a drug, contributes to further addiction to the product, especially if it contains toluene. In addition to serious neurodegenerative damage, it can also damage vital organs such as the liver, heart or brain, affecting cognitive function.
References
Preparations of cannabis
Cannabis in Argentina
Cannabis in Brazil
Adulteration | Marihuana prensada | [
"Chemistry"
] | 591 | [
"Adulteration",
"Drug safety"
] |
68,524,973 | https://en.wikipedia.org/wiki/Andy%20Fitzgerald | Andrew Fitzgerald (3 December 1885 - 24 November 1969) was an Irish hurler. At club level he played with Blackrock and was also a member of the Cork senior hurling team. He usually lined out as a goalkeeper.
Career
Fitzgerald first came to prominence at club level with Blackrock. After establishing himself as goalkeeper on the club's senior team, he went on to win three County Championship titles in four years. Fitzgerald's performances at club level saw him being selected for the Cork senior hurling team and he made his first appearance in the 1909 Munster final defeat by Tipperary. He also lined out in the 1912 All-Ireland final defeat by Kilkenny, having earlier claimed his only senior silverware when Cork won the Munster Championship title. Fitzgerald's last game for Cork was an All-Ireland semi-final defeat of Galway in 1914.
Personal life and death
Kelleher was born in Geraldine Place, Ballintemple in December 1885, the fifth of eight surviving children of Edward and Anne Fitzgerald (née Donoghue). The family were reasonably well-off and he trained as a mechanical engineer. Fitzgerald married Margaret Barry-Murphy in Cloughduv in 1916. Her elder brother, Barry Murphy, was a contemporary of Fitzgerald on the Cork team while her other brothers, John Barry-Murphy and Dinny Barry-Murphy, also lined out with Cork.
Fitzgerald died at his home in Victoria Road, Cork after a period of ill health on 24 November 1969.
Career statistics
Honours
Blackrock
Cork Senior Hurling Championship: 1910, 1912, 1913
Cork
Munster Senior Hurling Championship: 1912
References
1885 births
1969 deaths
Blackrock National Hurling Club hurlers
Cork inter-county hurlers
Hurling goalkeepers
Mechanical engineers | Andy Fitzgerald | [
"Engineering"
] | 345 | [
"Mechanical engineers",
"Mechanical engineering"
] |
68,525,295 | https://en.wikipedia.org/wiki/Tixagevimab/cilgavimab | Tixagevimab/cilgavimab, sold under the brand name Evusheld, is a combination of two human monoclonal antibodies, tixagevimab (AZD8895) and cilgavimab (AZD1061) targeted against the surface spike protein of SARS-CoV-2 used to prevent COVID-19. It is being developed by British-Swedish multinational pharmaceutical and biotechnology company AstraZeneca. It is co-packaged and given as two separate consecutive intramuscular injections (one injection per monoclonal antibody, given in immediate succession).
Development
In 2020, researchers at Vanderbilt University Medical Center discovered particularly potent monoclonal antibodies, isolated from COVID-19 patients infected with a SARS-CoV-2 circulating at that time. Initially designated COV2-2196 and COV2-2130, antibody engineering was used to transfer their SARS-CoV-2 binding specificity to IgG scaffolds that would last longer in the body, and these engineered antibodies were named AZD8895 (tixagevimab) and AZD1061 (cilgavimab), respectively (and the combination was called AZD7442).
To evaluate the potential of the antibodies as monoclonal antibody based prophylaxis (prevention), the 'Provent' clinical trial enrolled 5,000 high risk but not yet infected individuals and monitored them for 15 months. The trial reported that those receiving the cocktail showed a 77% reduction in symptomatic COVID-19 and that there were no severe cases or deaths. AstraZeneca also found that the antibody cocktail "neutralizes recent emergent SARS-CoV-2 viral variants" including the Delta variant, and the Omicron variant.
In contrast to pre-exposure prophylaxis, the Storm Chaser study of already-exposed people (post-exposure prophylaxis) did not meet its primary endpoint, which was prevention of symptomatic COVID-19 in people already exposed. AZD7442 was administered to 1,000 volunteers who had recently been exposed to COVID.
Society and culture
Legal status
In October 2021, the Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA) started a rolling review of tixagevimab/cilgavimab, which is being developed by AstraZeneca AB, for the prevention of COVID-19 in adults. It was approved for medical use in the European Union in March 2022.
Also in October 2021, AstraZeneca requested emergency use authorization for tixagevimab/cilgavimab to prevent COVID-19 from the US Food and Drug Administration (FDA).
In November 2021, Bahrain authorized it for emergency use.
In December 2021, the US FDA granted emergency use authorization (EUA) of this combination to prevent COVID-19 (before exposure) in people with weakened immunity or who cannot be fully vaccinated due to a history of severe reaction to coronavirus vaccines. and in certain people aged 12 years of age and older weighing at least . The product is only authorized for those individuals who are not infected with the SARS-CoV-2 virus and who have not recently been exposed to an individual infected with SARS-CoV-2. The EUA was revoked in January 2023.
In March 2022, the Committee for Medicinal Products for Human Use of the European Medicines Agency adopted a positive opinion, recommending the granting of a marketing authorization for the medicinal product Evusheld, intended for the pre-exposure prophylaxis of COVID-19 in adults and adolescents aged 12 years and older weighing at least . The applicant for this medicinal product is AstraZeneca AB. It has since been granted approval for use in the UK and in the European Union.
In January 2023, the FDA revised the EUA for Evusheld to limit its use to when the combined frequency of non-susceptible SARS-CoV-2 variants nationally is less than or equal to 90%. Based on this revision, Evusheld is not authorized for use in the US.
References
External links
AstraZeneca
Combination antiviral drugs
COVID-19 drug development
Experimental monoclonal antibodies
Monoclonal antibodies
Withdrawn drugs | Tixagevimab/cilgavimab | [
"Chemistry"
] | 909 | [
"Drug discovery",
"COVID-19 drug development",
"Drug safety",
"Withdrawn drugs"
] |
68,527,580 | https://en.wikipedia.org/wiki/Dead-character%20costume | Stage clothes specially designed or modified for actors portraying characters killed on screen or stage are used to depict gunshot or stab wounds, damage and the visual aftermath of violence. They are prepared by integrating special effect devices such as blood squibs or prosthetics. Despite the character being "killed" only once on-screen, multiple identical costumes are typically used for several takes and scenes to ensure consistency and continuity, as the irreversible damage caused by squibs or blood effects limit their reusability. They are sent to separate costume racks and disposed of afterwards, unlike other clothing articles that may return to the costume shop. These costumes serve as a metaphorical canvas to portray injury and death without the need for digital post-production effects and help filmmakers tell impactful, dramatic or even comedic stories.
Costume considerations
Costume selection should consider script requirements, possibility for modification, aesthetics, and budget. If fake blood is used, the outfit's colour should be bright or have sufficient set lighting to show bloodstains. Typically, 3-6 or even 8 identical stunt pieces are modified for the planned takes, rehearsals, backups and tests, and one hero piece without modifications is used for close-ups and prior scenes. Sufficient duplicates ensure smooth execution.
Costumes used for bullet hit squibs
A dead-character costume is one of the most significant components of a blood squibs effect, especially in action or crime scenes that involve gunfire. These squibs simulate a burst of a bullet wound and a fake blood packet hidden beneath the costume. Designated areas of the fabric where the squibs are placed are first weakened (often by legislation) by cutting, sanding, scoring, grating or plunging a scoring tool, and sometimes, they are cut open from the inside to affix the squibs. As a result, spare or unused costumes are usually unsalvageable.
Preparation of the costume
The preparation of a dead-character costume involves determining the number, sequence, and location of bullet holes (~50 mm diameter) based on the script. To maintain an intact appearance from a distance, the area is weakened and glued or taped to create realistic fraying when the squibs trigger. Squib assemblies, which are large and heavy, are securely attached to the inside of the costume to ensure the blood effect is directed outward. The lining and filling may be modified to reduce bulk, though multiple squibs can still add significant weight and unnatural bulges, affecting movement and appearance. Costumers aim to minimise visibility of squib placements, with subtle scoring or stippling techniques and using post-production to erase visible bullet holes before the squibs are fired.
In some cases, jackets with multiple frontal squibs are fitted with an additional rear zip, allowing actors to wear them from the back to minimise disturbance to the squibs. Fastening all closures is crucial for both visual consistency and safety, as it prevents the squibs from being exposed or aiming in unintended directions.
Reusing or salvaging dead-character costumes
Producing convincing bullet hit squib effects often requires a substantial wardrobe budget, though some costumes can be reused or salvaged. Thin fabrics, like cycling jerseys, where a squib can easily blow open the thin fabric, can be used for a blood squib stunt without weakening the fabric and unused spares can be salvaged. More durable clothing, such as jackets (e.g. waterproof, parka and down), can be reused across several takes, thus reducing the number of duplicates. Bullet holes are completely cut open and loosely glued or taped back together, as shown in the demonstration image in the gallery. Between takes, blood squibs are replaced, and the jacket is wiped clean again. Other advantages of using a jacket as a dead character costume include:
the insulation provides additional padding
versatility in many scripts
easy to hide multiple squibs, wiring and equipment
more sophisticated appearance
comfortable for extended filming or performing periods
The main disadvantage is that this requires more time for resets between takes.
Specific modifications for a down jacket, such as repacking down fillings in a taffeta pocket or a plastic pouch, help maintain their puffy appearance.
Using non-staining simulants (e.g. water) during rehearsals or dry simulants (e.g. dust, powder) also facilitates cleanup.
When costumes cannot be altered or damaged, realistic blood stains can be achieved using acrylic painted nylon tulle mesh and added ripped fabric material for bullet hole textures. This method allows repositioning before sewing and removal after production for costume reuse. However, it does not replicate the blood spray effect of a bullet hit squib, potentially requiring CGI to achieve this effect.
Performing with bullet hit squibs
Costume containing blood squibs and equipment is visibly bulkier and heavier, which requires care during dressing and performance to avoid damaging the squibs. For safety reasons, it is generally advised to change into the dead character costume immediately before the shot to prevent accidental triggering or equipment malfunction, unless practical reasons necessitate switching from the hero costume to the stunt version earlier.
Post-production
Spent and unspent costumes, whether salvageable or not, are kept until post-production is complete in case additional footage is needed. This ensures that all necessary footage is captured and allows for reshoots if required. Afterwards, they can become souvenirs, be auctioned as memorabilia, repaired, or donated depending on the production's needs. An example is winter coats with bullet holes that have been repaired and donated.
See also
Bodily mutilation in film
Bullet hit squib
Fake blood
Practical effect
Pyrotechnics
Special effect
Squib (explosive)
References
Costume design
Stagecraft
Special effects | Dead-character costume | [
"Engineering"
] | 1,190 | [
"Costume design",
"Design"
] |
68,527,621 | https://en.wikipedia.org/wiki/Richard%20John%20Pentreath | Richard John (usually known as ‘Jan’) Pentreath is a British marine scientist who made major contributions to radioecology, particularly with regard to alpha-emitting nuclides in the marine environment. He went on to broaden the international system of radiological protection to include animals and plants with respect to different exposure situations, as well as protection of the animal as patient in veterinary medicine. He also played a major role in the success of the National Rivers Authority and its subsequent merging with other bodies to form the Environment Agency.
Education
Pentreath was a County scholar to Queen Mary College, University of London, graduating in zoology, with special honours in marine zoology. After winning a Commonwealth scholarship he did a PhD on ophiuroids (brittle stars) at the University of Auckland, New Zealand, being the first to do so at their Leigh Marine Laboratory, and returned to the UK to take up a Science Research Council Fellowship at the Fisheries Radiobiological Laboratory (FRL) at Hamilton Dock.
Research and career
Becoming a member of staff at the Fisheries Radiobiological Laboratory in 1969, Pentreath carried out research into the behaviour, fate, and accumulation of various radionuclides (fission and neutron activation products, and those of the transuranic series) by marine fish and shellfish as well as the use of radiotracers to study various marine pollutants, being awarded a DSc (London) in 1980. He then became Head of Research (1985) at FRL, and then later deputy director of Fisheries Research. Pentreath was heavily involved with international organisations, particularly the International Atomic Energy Agency and the Nuclear Agency of the OECD, in relation to exchanging information and developing methodologies for these new areas of research, and in relation to the control of low-level dumping of radioactive wastes at sea, plus research into the feasibility of disposing of high level radioactive wastes into the tectonic plates of the ocean floor.
He was responsible for the task of cleaning up the rivers and estuaries of England and Wales. He was seconded to the Department of the Environment (DoE) in 1994 to help create the Environment Agency (EA) in 1995, then becoming its Chief Scientist and Director of Environmental Strategy.
In 2000 Pentreath became Professor of Environmental Sciences and Principal Research Fellow at the Environmental Systems Science Centre (ESSC), School of Mathematics, Meteorology and Physics, University of Reading until 2006, then becoming Professor Emeritus. During this period he was also appointed by the Secretary of State to the UK's Joint Nature Conservation Committee (2000-2006).
Pentreath produced a series of papers on the problem of demonstrating protection of the environment with respect to ionizing radiation, and how it could be addressed by the development of a set of ‘Reference Animals and Plants’. Pentreath has also continued to be involved with marine radioecology, and was recently engaged with evaluating the impact of nuclear powered vessels on the marine environment.
Awards and honors
Commonwealth scholar (1965)
Science Research Council Fellow (1968)
FRSB (1980)
FSRP (1989)
DSc (hc) University of Hertfordshire (1998)
DSc (hc) University of West of England (1999)
DSc (hc) University of Plymouth (2002)
Emeritus research fellow, Centre for Environment, Fisheries and Aquaculture Science (2014)
Emeritus Member ICRP Main Commission (2014)
Hon. FSRP (2018)
Publications
Occurrence of plutonium and americium in plaice from the north–eastern Irish Sea.
Transuranic nuclides in plaice (Pleuronectes platessa) from the north-eastern Irish Sea.
Radiological protection of the patient in veterinary medicine and the role of ICRP.
Radiological protection and the exposure of animals as patients in veterinary medicine.
ICRP's approach to protection of the living environment under different exposure situations.
ICRP Publication 124: Protection of the Environment under Different Exposure Situations.
Clarifying and simplifying the management of environmental exposures under different exposure situations.
Ethics, genetics and dynamics: An emerging systematic approach to radiation protection of the environment.
References
Biogeochemists
Academics of the University of Reading
University of Auckland alumni
Alumni of Queen Mary University of London
Living people
Year of birth missing (living people) | Richard John Pentreath | [
"Chemistry"
] | 876 | [
"Geochemists",
"Biogeochemistry",
"Biogeochemists"
] |
68,528,939 | https://en.wikipedia.org/wiki/Carol%20Kendall%20%28scientist%29 | Carol Kendall is a hydrologist known for her research tracking nutrients and contaminants in aquatic ecosystems using isotopic tracers.
Education and career
From the University of California, Riverside, Kendall earned a B.S. in geology (1973) and a masters in geology (1976). Following her masters she took a position as a geochemist at California Institute of Technology where she remained until 1979. From 1980 until 1990, Kendall was a research hydrologist at the United States Geological Survey in Reston, Virginia. While working full-time, she earned a Ph.D. from the University of Maryland, College Park. Starting in 1990, Kendall was the project lead for the National Research Program's Isotope Tracers Project within the United States Geological Survey.
Research
Kendall is known for her research combining multiple stable isotopes to track nutrients through ecosystems. Her early research optimized methods to convert water into hydrogen for isotopic analysis. She has worked in multiple ecosystems, including the San Joaquin River, the Sacramento River, and in San Francisco Bay. Her large-scale survey of oxygen-18 and deuterium in water samples collected from rivers across the United States serves as a proxy for modern precipitation. Her research into the carbon and nitrogen isotopes in particulate material provided a baseline for research into food webs, nutrient transport research, and global patterns of nitrogen in soil and plants. Kendall's research has also used isotope fractionation to track the flow of carbon from streams to the atmosphere and to differentiate between sources of nitrogen.
Selected publications
Kendall, Carol and J. J. McDonnell, Editors (1998). "Isotope Tracers in Catchment Hydrology", Elsevier Science Publishers, 816p,
Awards and honors
Meritorious Service Awards, United States Geological Survey (1994, 2002)
Fellow, American Geophysical Union (2010)
Distinguished alumni, University of Maryland (2011)
Walter Langbein Lecture, American Geophysical Union (2014)
References
External links
November 21, 2013
University of California, Riverside alumni
University System of Maryland alumni
Fellows of the American Geophysical Union
United States Geological Survey personnel
Living people
Women geologists
Hydrologists
Biogeochemists
Year of birth missing (living people) | Carol Kendall (scientist) | [
"Chemistry",
"Environmental_science"
] | 444 | [
"Geochemists",
"Hydrology",
"Biogeochemistry",
"Biogeochemists",
"Hydrologists"
] |
68,529,153 | https://en.wikipedia.org/wiki/Otto%20Neubauer | Otto Neubauer (8 April 1874 – 24 November 1957) was a Bohemia-born physician and biochemist who was responsible for several clinical diagnostic innovations including the Neubauer-Fischer test to evaluate kidney function and the Neubauer counting chamber.
Life and work
Neubauer was born in Karlsbad (then in Bohemia) to physician Wolfgang and Hedwig Arnstein née Sadler. In 1892 he passed the examination for qualifying admission to a university after studying at the humanistic gymnasium of Chomutov. He then went to the German University in Prague he received a medical degree in 1898 and became interested in physiological chemistry through the influence of Karl H. Huppert. He then joined as an assistant to Friedrich von Müller at Basel. He moved to Munich in 1902. In 1908 he joined the University of Munich and served in a reserve hospital during World War I. His major work in this period was on amino acid metabolism in human health and disease. Neubauer and Konrad Fromherz examined the role of pyruvic acid in fermentation. He innovated several clinical diagnostics including tests of peptolytic activity. Gastric juice incubated with glycyl-tryptophan for twenty four hours tested with bromine to see if free tryptophan causes a rose-violet colour was used as an indication of stomach carcinoma. In 1918 he became head physician at Schwabinger Hospital, working there until his dismissal by the Nazi government in June 1933 as a person of Jewish ancestry. In 1920 he developed a blood pressure measuring device and still later a measuring slide (known as a Neubauer slide or Neubauer counting chamber) for counting cells under a microscope. With assistance and support from The Society for the Protection of Science and Learning, he emigrated to England in 1939 along with his wife Lilly Caroline (1876-1962, who was married to composer Fritz Cassirer until his death) and worked in Oxford for the remainder of his life. His contributions included studies on arsenic and other chemicals as carcinogens.
Neubauer's students included Siegfried Thannhauser, Rudolf Schindler, and Konrad Dobriner.
References
1874 births
1957 deaths
Jewish scientists
Biochemists
Academic staff of the Munich University of Applied Sciences
Jews who emigrated to escape Nazism
Physicians from Austria-Hungary | Otto Neubauer | [
"Chemistry",
"Biology"
] | 476 | [
"Biochemistry",
"Biochemists"
] |
68,530,674 | https://en.wikipedia.org/wiki/John%20Smillie%20%28mathematician%29 | John David Smillie (born February 18, 1953, in Ithaca, New York) is an American mathematician, specializing in dynamical systems.
Biography
His father, David Smillie, was a professor of psychology.
John Smillie graduated in 1974 with a B.A. in mathematics from New College of Florida. At the University of Chicago he graduated with an M.S. in 1975 and a Ph.D. in 1977. His Ph.D. thesis Affinely flat manifolds was supervised by Richard Lashof. From 1977 to 1980 Smillie was an instructor at Princeton University. For the academic year 1980–1981 he was at the Institute for Advanced Study. He was a postdoc for the academic year 1981–1982 at the University of California, Berkeley, and for the academic year 1982–1983 at Graduate Center of the City University of New York (CUNY). At CUNY Smillie was an assistant professor from 1983 to 1986 and an associate professor from 1986 to 1989 at Lehman College and CUNY Graduate Center. At Cornell University has he was a visiting associate professor from 1986 to 1987, an associate professor from 1987 to December 1990, and a full professor from January 1991 to July 2015, when he became an emeritus professor. At Cornell University he was the chair of the mathematics department from 1999 to 2002. In 2013 he became a professor at the University of Warwick. He is married to the mathematician Karen Vogtmann. The couple moved in 2013 to England and settled in Kenilworth.
His research deals with "polygonal billiards and dynamics of flows on Teichmüller space; analysis of algorithms; and diffeomorphisms of surfaces", as well as "translation surfaces and complex dynamics in higher dimensions".
Smillie has held visiting positions at several institutions, including the University of Illinois Chicago, the École normale supérieure de Lyon, the Institut des Hautes Études Scientifiques, the Mathematical Sciences Research Institute in Berkeley, the Research Institute for Mathematical Sciences of Kyoto University, and the Mathematical Institute of the Hausdorff Center for Mathematics in Bonn. He has given talks in the USA, Canada, France, Italy, Israel, Brazil, and China. In 2002 he was an invited speaker at the International Congress of Mathematicians in Beijing.
Selected publications
References
External links
1953 births
Living people
20th-century American mathematicians
21st-century American mathematicians
Dynamical systems theorists
New College of Florida alumni
University of Chicago alumni
CUNY Graduate Center faculty
Cornell University faculty
Academics of the University of Warwick
Lehman College faculty | John Smillie (mathematician) | [
"Mathematics"
] | 518 | [
"Dynamical systems theorists",
"Dynamical systems"
] |
68,530,819 | https://en.wikipedia.org/wiki/3%2C3-Dimethylhexane | 3,3-Dimethylhexane is a colourless, odourless liquid, chemical compound in the family of hydrocarbons which has a formula of C8H18. It is an isomer of octane, where two methylene hydrogens at the third position in a hexane molecule have been replaced with two methyl groups.
3,3-Dimethylhexane is found in various herbs and spices. It is also a constituent in the oil of osmanthus fragrans and Ginseng. 3,3-Dimethylhexane is an acyclic alkane, where there are no cycles in the structure of the molecule.
It is one of the main extracts from cinnamon bark using supercritical carbon dioxide extraction, with it being 10.6% of the extracted material; it is second behind trans-cinnamaldehyde with it being 32.1% of the extracted material.
Uses
3,3-dimethylhexane can be used in the production of phytochemical compounds which are effective in the removal of heavy metals, since when cyanobacteria are exposed to aliphatic compounds, or alkanes, and some heavy metals they produce phytochemical compounds which are effective in the removal of heavy metals. 3,3-dimethylhexane being both an alkane and an aliphatic compound can be used in this process.
References
Hydrocarbons | 3,3-Dimethylhexane | [
"Chemistry"
] | 306 | [
"Organic compounds",
"Hydrocarbons"
] |
68,531,530 | https://en.wikipedia.org/wiki/Ocean%20optics | Ocean optics is the study of how light interacts with water and the materials in water. Although research often focuses on the sea, the field broadly includes rivers, lakes, inland waters, coastal waters, and large ocean basins. How light acts in water is critical to how ecosystems function underwater. Knowledge of ocean optics is needed in aquatic remote sensing research in order to understand what information can be extracted from the color of the water as it appears from satellite sensors in space. The color of the water as seen by satellites is known as ocean color. While ocean color is a key theme of ocean optics, optics is a broader term that also includes the development of underwater sensors using optical methods to study much more than just color, including ocean chemistry, particle size, imaging of microscopic plants and animals, and more.
Key terminology
Optically deep
Where waters are “optically deep,” the bottom does not reflect incoming sunlight, and the seafloor cannot be seen by humans or satellites. The vast majority of the world's oceans by area are optically deep. Optically deep water can still be relatively shallow water in terms of total physical depth, as long as the water is very turbid, such as in estuaries.
Optically shallow
Where waters are “optically shallow,” the bottom reflects light and often can be seen by humans and satellites. Here, ocean optics can also be used to study what is under the water. Based on what color they appear to sensors, researchers can map habitat types, including macroalgae, corals, seagrass beds, and more. Mapping shallow-water environments requires knowledge of ocean optics because the color of the water must be accounted for when looking at the color of the seabed environment below.
Inherent optical properties (IOPs)
Inherent optical properties (IOPs) depend on what is in the water. These properties stay the same no matter what the incoming light is doing (daytime or nighttime, low sun angle or high sun angle).
Absorption
Water with large amounts of dissolved substances, such as lakes with large amounts of colored dissolved organic matter (CDOM), experience high light absorption. Phytoplankton and other particles also absorb light.
Scattering
Areas with sea ice, estuaries with large amounts of suspended sediments, and lakes with large amounts of glacial flour are examples of water bodies with high light scattering. All particles scatter light to some extent, including plankton, minerals, and detritus. Particle size effects how much scattering happens at different colors; for example, very small particles scatter light exponentially more in the blue colors than other colors, which is why the ocean and the sky are generally blue (called Rayleigh scattering). Without scattering, light would not “go” anywhere (outside of a direct beam from the sun or other source) and we would not be able to see the world around us.
Attenuation
Attenuation in water, also called beam attenuation or the beam attenuation coefficient, is the sum of all absorption and scattering. Attenuation of a light beam in one specific direction can be measured with an instrument called a transmissometer.
Apparent optical properties (AOPs)
Apparent optical properties (AOPs) depend on what is in the water (IOPs) and what is going on with the incoming light from the Sun. AOPs depend most strongly on IOPs and only depend somewhat on incoming light aka the “light field.” Characteristics of the light field that can affect AOP measurements include the angle at which light hits the water surface (high in the sky vs. low in the sky, and from which compass direction) and the weather and sky conditions (clouds, atmospheric haze, fog, or sea state aka roughness of the surface of the water).
Remote sensing reflectance (Rrs)
Remote sensing reflectance (Rrs) is a measure of light radiating out from beneath the ocean surface at all colors, normalized by incoming sunlight at all colors. Because Rrs is a ratio, it is slightly less sensitive to what is going on with the light field (such as the angle of the sun or atmospheric haziness).
Rrs is measured using two paired spectroradiometers that simultaneously measure light coming in from the sky and light coming up from the water below at many wavelengths. Since it is a measurement of a light-to-light ratio, the energy units cancel out, and Rrs has the units of per steradian (sr-1) due to the angular nature of the measurement (upwelling light is measured at a specific angle, and incoming light is measured on a flat plane from a half-hemispherical area above the water surface).
Light attenuation coefficient (Kd)
Kd is the diffuse (or downwelling) coefficient of light attenuation (Kd), also called simply light attenuation, the vertical extinction coefficient, or the extinction coefficient. Kd describes the rate of decrease of light with depth in water, in units of per meter (m−1). The “d” stands for downwelling light, which is light coming from above the sensor in a half-hemispherical shape (aka half of a basketball). Scientists sometimes use Kd to describe the decrease in the total visible light available for plants in terms of photosynthetically active radiation (PAR) – called “Kd(PAR).” In other cases, Kd can describe the decrease in light with depth over a spectrum of colors or wavelengths, usually written as “Kd(λ).” At one color (one wavelength) Kd can describe the decrease in light with depth of one color, such as the decrease in blue light at the wavelength 490 nm, written as “Kd(490).”
In general, Kd is calculated using Beer's Law and a series of light measurements collected from just under the water surface down through the water at many depths.
Closure
“Closure” refers to how optical oceanographers measure the consistency of models and measurements. Models refer to anything that is not explicitly measured in the water, including satellite-derived variables that are estimated using empirical relationships (for example, satellite-derived chlorophyll-a concentration is estimated from the ratios between green and blue remote sensing reflectance using an empirical relationship). Closure includes measurement closure, model closure, model-data closure, and scale closure. Where model-data closure experiments show misalignment between data and models, the cause of the misalignment may be due to measurement error, issues with the model, both, or some other external factor.
Focus areas
Ocean optics has been applied to study topics like primary production, phytoplankton, zooplankton, shallow-water habitats like seagrass beds and coral reefs, marine biogeochemistry, heating of the upper ocean, and carbon export to deep waters by way of the ocean biological pump. The portion of the electromagnetic spectrum usually involved in ocean optics is ultraviolet through infrared, about 300 nm to less than 2000 nm wavelengths.
Common optical sensors used in oceanography
The most widely used optical oceanographic sensors are PAR sensors, chlorophyll-a fluorescence sensors (fluorometers), and transmissometers. These three instruments are frequently mounted on CTD(conductivity-temperature-depth)-rosette samplers. These instruments have been used for many years on CTD-rosettes in global repeat oceanographic surveys like the CLIVAR GO-SHIP campaign.
Particle size in the ocean
Optical instruments are often used to measure the size spectrum of particles in the ocean. For example, phytoplankton organisms can range in size from a few microns (micrometers, μm) to hundreds of microns. The size of particles is often measured to estimate how quickly particles will sink, and therefore how efficiently plants can sequester carbon in the ocean's biological pump.
Imaging of ocean particles and organisms
Scientists study individual tiny objects such as plankton and detritus particles using flow cytometry and in situ camera systems. Flow cytometers measure sizes and take photographs of individual particles flowing through a tube system; one such instrument is the Imaging FlowCytoBot (IFCB). In situ camera systems are deployed over the side of a research vessel, alone or attached to other equipment, and they capture photographs of the water itself to image the particles present in the water; one such instrument is the Underwater Vision Profiler (UVP). Other imaging technologies used in the ocean include holography and particle imaging velocimetry (PIV), which uses 3D video footage to track the movement of underwater particles.
Research in support of satellite remote sensing
Ocean optics research done “in situ” (from research vessels, small boats, or on docks and piers) supports research that uses satellite data. In situ optical measurements provide a way to: 1) calibrate satellite sensors when they are just beginning to collect data, 2) develop algorithms to derive products or variables like chlorophyll-a concentration, and 3) validate data products derived from satellites. Using satellite data, researchers estimate things like particle size, carbon, water quality, water clarity, and bottom type based on the color profile as seen by satellite; all of these estimations (aka models) must be validated by comparing them to optical measurements made in situ. In situ data are often available from publicly accessible data libraries like the SeaBASS data archive.
Major contributing scientists
Oceanographers, physicists, and other scientists who have made major contributions to the field of ocean optics include (incomplete list):
David Antoine, Marcel Babin, Paula Bontempi, Emmanuel Boss, Annick Bricaud, Kendall Carder, Ivona Cetinic, Edward Fry, Heidi Dierssen, David Doxaran, Gene Carl Feldman, Howard Gordon, Chuanmin Hu, Nils Gunnar Jerlov, George Kattawar, John Kirk, ZhongPing Lee, Hubert Loisel, Stephane Maritorena, Michael Mishchenko, Curtis Mobley, Bruce Monger, Andre Morel, Michael Morris, Norm Nelson, Mary Jane Perry, Rudolph Preisendorfer, Louis Prieur, Chandrasekhara Raman, Collin Roesler, Rüdiger Röttgers, David Siegel, Raymond Smith, Heidi Sosik, Dariusz Stramski, Michael Twardowski, Talbot Waterman, Jeremy Werdell, Ken Voss, Charles Yentsch, and Ronald Zaneveld.
Education
While ocean optics is an interdisciplinary field of study applies to a wide range of topics, it is not often taught as a course in graduate programs for marine science and oceanography. Two summer-term courses have been developed for graduate students from many different institutions. First, there is a summer lecture series operated by the International Ocean Colour Coordinating Group (IOCCG) which usually takes place in France. Second, there is an ongoing course in the United States called the “Optical Oceanography Class” or “Ocean Optics Class” in Washington State and later in Maine, which has been running continuously since 1985.
For independent learning, Curt Mobley, Collin Roesler, and Emmanuel Boss wrote the Ocean Optics Web Book as an open-access online guide.
See also
Related fields and topics:
Atmospheric optics
Color of water
Electromagnetic spectrum
History of optics
Oceanography
Ocean color
Optical depth
Spectral color
Transparency and translucency
Visible spectrum
Water clarity
Water remote sensing
Water quality
Inherent and apparent optical properties and in-water methods:
Absorption (electromagnetic radiation)
Argo (oceanography)
Attenuation coefficient
Beer-Lambert Law
Marine optical buoy
Scattering
Secchi disk
Remote sensing and radiometric methods:
Albedo
Atmospheric correction
NASA Earth Science
Spectralon
References
Further reading
Ocean Optics Web Book
Oceanography
Applied and interdisciplinary physics
Scattering, absorption and radiative transfer (optics)
Optics
Marine biology
Aquatic ecology
Biological oceanography
Water
Earth sciences
Earth observation in-situ sensors | Ocean optics | [
"Physics",
"Chemistry",
"Biology",
"Environmental_science"
] | 2,443 | [
"Environmental instrumentation",
" absorption and radiative transfer (optics)",
"Applied and interdisciplinary physics",
"Optics",
"Hydrology",
"Water",
"Oceanography",
"Marine biology",
"Scattering",
" molecular",
"Ecosystems",
"Earth observation in-situ sensors",
"Atomic",
"Aquatic ecolo... |
68,531,682 | https://en.wikipedia.org/wiki/Oxalate%20nitrate | An oxalate nitrate is a chemical compound or salt that contains oxalate and nitrate anions (NO3− and C2O42-). These are mixed anion compounds. Some have third anions. Oxalate acts as a ligand, which normally complexes two metal atoms.
Naming
An oxalate nitrate compound may also be called a nitrate oxalate. In chemical formulae, oxalate may be indicated by "ox". As a ligand oxalate is termed "oxalato", and nitrate, "nitrato".
Production
Most oxalate nitrates are formed by crystallisation from water solutions. One issue is the insolubility of metal oxalates.
Properties
On heating, oxalate nitrates lose NO2, NO, CO, and CO2 and form metal carbonates or oxides.
Related
Related to these are the oxalate phosphates and oxalate perchlorates.
List
References
Nitrates
Oxalates
Mixed anion compounds | Oxalate nitrate | [
"Physics",
"Chemistry"
] | 207 | [
"Matter",
"Mixed anion compounds",
"Oxidizing agents",
"Nitrates",
"Salts",
"Ions"
] |
60,664,865 | https://en.wikipedia.org/wiki/CARD-CC%20family | The CARD-CC protein family is defined by an evolutionary conserved "caspase activation and recruitment domain" (CARD) and a coiled-coil (CC) domain. Coiled-coils (CC) act as oligomerization domains for many proteins such as structural and motor proteins, and transcription factors. This means that monomers are converted to macromolecular complexes by polymerization. In humans and other jawed vertebrates, the family consists of CARD9 and the three "CARD-containing MAGUK protein" (CARMA) proteins CARD11 (CARMA1), CARD14 (CARMA2) and CARD10 (CARMA3). Although the MAGUK protein DLG5 contains both a CARD domain and a CC domain, it does not belong to the same family as the CARD-CC proteins since the evolutionary origin of its CARD domain is very likely to be different.
Evolution and species distribution
The protein family is ancient and can be found as far back as Cnidaria, but has almost exclusively been studied in humans and mice. Notably, the protein family is absent in insects and nematodes, which makes it impossible to study its function in the most popular invertebrate model organisms (Drosophila and C. elegans). Invertebrates only have a CARD9-like ancestral CARD-CC member, and the earliest occurrence of a CARD-CC member with the CARMA domain composition is in the jawless vertebrate hagfish. Already in sharks are all four CARD-CC family members present, indicating that the 3 distinct CARMA CARD-CC family members were formed by two duplication events just before or very early in the jawed vertebrate evolution, almost half a billion years ago. The four CARD-CC ohnologous members in mice and humans differ in expression domains, where CARD9 is mostly expressed in myelocytes, CARD11 in lymphocytes, while CARD10 and CARD14 are mostly expressed in non-haematopoetic cells. This gene expression differentiation between the four CARD-CC family members conserved at least as far back as frogs (Xenopus tropicalis) and fish (Danio rerio), indicating that the four CARD-CC family members have had distinct functions since early jawed vertebrate evolution.
Functions
A common theme for all four CARD-CC family proteins in mice and humans is that they are activated by different protein kinase C isoforms, and recruit BCL10 and the paracaspase MALT1 upon activation, forming a so-called CBM complex. There are four different CBM complexes, defined by which CARD-CC family member that is responsible for its assembly: CBM-9 (CARD9), CBM-1 (CARD11/CARMA1), CBM-2 (CARD14/CARMA2) and CBM-3 (CARD10/CARMA3). CBM complex assembly results in recruitment of TRAF6 to MALT1 and downstream activation of NF-κB transcriptional activity and expression of pro-inflammatory cytokines. The different CARD-CC family members show different expression pattern and gain- or loss of function mutation in the different CARD-CC family proteins cause different phenotypes.
Loss-of-function mutations in CARD9 disrupts lectin receptor signaling like Dectin 1, which causes enhanced susceptibility to fungal infections.
Gain-of-function variants in CARD9 appear to be associated to fibromyalgia, and possibly the comorbidities constipation, Irritable bowel syndrome and other psychosomatic sequelæ in the UK biobank association between exome sequences and health data.
Strong loss-of-function mutations in CARD11 cause severe defects in lymphocyte function since it is a critical downstream signal mediator in T- and B-cell antigen receptor signaling, which results in severe combined immunodeficiency (SCID).
Weak (hypomorphic) mutations in CARD11 causes atopic dermatitis disease.
Gain-of-function mutations in CARD11 can result in B-cell lymphoma or BENTA.
Gain-of-function mutations in CARD14 results in psoriasis or PRP.
There are indications that loss-of-function mutations in CARD14 could result in atopic dermatitis due to disrupted immune responses against skin microbes.
There are no obvious gain- or loss-of-function mutations in CARD10, but it is sometimes over-expressed in certain cancer variants, and there is a SNP in CARD10 associated to glaucoma.
References | CARD-CC family | [
"Biology"
] | 949 | [
"Protein families",
"Protein classification"
] |
60,665,098 | https://en.wikipedia.org/wiki/Agkud | Agkud is a traditional Filipino fermented rice paste or rice wine of the Manobo people from Bukidnon. Agkud specifically refers to fermented three-day-old paste made with rice, ginger, sugarcane juice, and or (the yeast starter culture, also known as bubud or tapay in Tagalog and Visayan languages). The rice wine pangasi is made from agkud except fermented longer for at least one month. Modern versions of the agkud can use other sources of starch like cassava, sorghum, or corn. Hot peppers may also be used instead of ginger. Agkud is drunk during celebrations, rituals, and various social events.
See also
Bahalina
Basi
Kaong palm vinegar
Nipa palm vinegar
Pangasi
Tapuy
References
Fermented drinks
Philippine alcoholic drinks
Filipino cuisine | Agkud | [
"Biology"
] | 180 | [
"Fermented drinks",
"Biotechnology products"
] |
60,665,128 | https://en.wikipedia.org/wiki/Roland%20SP-808 | The Roland SP-808 GrooveSampler and SP-808EX/E-Mix Studio are both discontinued workstations, which function as digital samplers, synthesizers, and music sequencers. The digital samplers are a part of the long line of both Roland Corporation's and Boss Corporation's Groove Gear, which includes the more popular and successful Boss SP-303 and Roland SP-404 versions.
Background
Being an early installment in the SP lineage, the SP-808 GrooveSampler was originally released in the year of 1998. Sometime in the year 2000, the sampler was updated, redesigned, and released as the SP-808EX, with the additional name of "e-Mix Studio." Despite receiving an upgrade, both versions of the SP-808 have and also lack certain features of the succeeding SP installments.
Features
Groovesampler
The original Roland SP-808 GrooveSampler can play up to four stereo samples simultaneously, with the sample rates of 44.1 and 32 kHz. The maximum sample time allowed is 25 minutes of stereo at the rate of 44.1 kHz. Being an predecessor to more popular SPs, the sampler itself can hold over 1,000 samples, while 100MB Zip disks can store up to 1024 samples, roughly amounting to 64 minutes. Unlike some of the succeeding SP installments, the sampler has no USB or CompactFlash card option. Furthermore, audio samples can only be stored, read, and transferred directly from the zip drive rather than internal RAM. In an effort to maximize storage space on zip disks, Roland decided against the use of AIFF and WAV audio formats. D-Beam controller is also included.
E-Mix Studio
Being an upgrade from the Groovesampler, the SP-808EX E-Mix Studio includes a virtual monophonic synthesizer for use with the step sequencer and D-Beam controller. Vocal effects, guitar multi-effects, a 10-band Vocoder, Voice Transformer, Mic Simulator, and a number DJ-oriented groove effects were added as well. A larger 250MB Zip drive replaces the original 100MB Zip. Sampling and recording time was extended possible to 61 stereo minutes. Expansion options include the OP-1 interface (6 analog outs, 2 digital I/Os, SCSI) and OP-2 interface (XLR I/Os, digital I/O, SCSI). In regards to storing and transporting audio, the method is the same as the Groovesampler.
Notable users
Despite receiving little popularity in comparison to the later SP-303 and SP-404 installments, Slipknot member 133 is known to have utilized the sampler for a number of years. DJ and music producer, Rekha Malhotra is known for utilizing the SP-808 as well.
References
Samplers (musical instrument)
D2
D-Beam
Grooveboxes
Music sequencers
Sound modules
Music workstations
Hip-hop production
Japanese inventions | Roland SP-808 | [
"Engineering"
] | 605 | [
"Music sequencers",
"Automation"
] |
60,665,163 | https://en.wikipedia.org/wiki/Bignay%20wine | Bignay wine, also known as bugnay wine, is a Filipino fruit wine made from the berries of the native bignay or bugnay tree (Antidesma bunius). It is deep red in color and is slightly sweet with a fruity fragrance.
References
External links
Fermented drinks
Philippine alcoholic drinks
Filipino cuisine
Fruit wines | Bignay wine | [
"Biology"
] | 69 | [
"Fermented drinks",
"Biotechnology products"
] |
60,665,199 | https://en.wikipedia.org/wiki/Duhat%20wine | Duhat wine, also called lomboy wine, is a Filipino fruit wine made from the fruits of black plum (duhat). It has a bright purple-red color. It is mostly produced in Southern Luzon.
References
Fermented drinks
Philippine alcoholic drinks
Filipino cuisine
Fruit wines | Duhat wine | [
"Biology"
] | 59 | [
"Fermented drinks",
"Biotechnology products"
] |
60,665,309 | https://en.wikipedia.org/wiki/Kinutil | Kinutil, also known as kinutir or kutir, is a Filipino alcoholic drink from the Visayas Islands and Mindanao. It is made from palm wine (tubâ) with raw egg yolks and/or homemade chocolate (tabliya). Some versions also add condensed milk, sugar, and carbonated softdrinks. A version made with chocolate and sugar in the island of Samar is known as dubado. It is typically paired with Filipino rice cakes (kakanin). The name means "stirred", from Visayan kutil ("to stir"). It is sometimes characterized as the "Filipino eggnog" or the "Filipino mudslide".
References
Fermented drinks
Philippine alcoholic drinks
Filipino cuisine
Christmas food | Kinutil | [
"Biology"
] | 159 | [
"Fermented drinks",
"Biotechnology products"
] |
60,665,437 | https://en.wikipedia.org/wiki/Kabarawan | Kabarawan was a traditional pre-colonial Filipino mead-like alcoholic drink. It was made from boiling the ground up aromatic bark of the kabarawan tree (Neolitsea villosa) until it was reduced to a thick paste. It was then mixed with an equal amount of honey and fermented. It was traditionally consumed from jars with reed or bamboo straws. The wine was mentioned by early Spanish colonists as being made by the Visayan people. However, the tradition has been lost in modern times. Kabarawan tree bark is also used to flavor other types of native wines, like intus and basi, which are both made from sugarcane juice.
See also
Bais
Mead
Sima
References
Fermented drinks
Philippine alcoholic drinks
Filipino cuisine
Mead | Kabarawan | [
"Biology"
] | 155 | [
"Fermented drinks",
"Biotechnology products"
] |
60,665,553 | https://en.wikipedia.org/wiki/Intus | Intus was a traditional pre-colonial Filipino alcoholic drink from the Visayas Islands and Mindanao. It was made by boiling sugarcane juice until it reduces to a thick syrup. It was then allowed to cool and mixed with the bark of the kabarawan tree (Neolitsea villosa) and fermented. The word intus (or initus) means "reduced" or "liquid thickened by boiling", from the Old Visayan verb itus ("to reduce"). Like the kabarawan drink, intus is extinct. The tradition was lost during the Spanish colonial period of the Philippines. Among the Lumad people of Mindanao, intus was flavored with langkawas (Alpinia galanga) or pal-la (Cordyline fruticosa) roots.
See also
Kabarawan
Basi
Palek
References
Fermented drinks
Philippine alcoholic drinks
Filipino cuisine | Intus | [
"Biology"
] | 187 | [
"Fermented drinks",
"Biotechnology products"
] |
60,665,747 | https://en.wikipedia.org/wiki/Palek | Palek, also known as paleg or mineovaheng, is a traditional Filipino alcoholic drink from the Batanes Islands made from fermented sugarcane juice. It is flavored with ebony bark (Diospyros ferrea), which turns the drink black. It is traditionally served in a halved coconut shell and passed from one person to the next.
See also
Basi
Intus
References
Fermented drinks
Philippine alcoholic drinks
Filipino cuisine | Palek | [
"Biology"
] | 94 | [
"Fermented drinks",
"Biotechnology products"
] |
60,667,144 | https://en.wikipedia.org/wiki/Bais%20%28wine%29 | Bais is a traditional Filipino mead from the Mandaya and Dibabawon Manobo of northeastern Mindanao. It is made from a mixture of honey and water at varying proportions. It is fermented for at least five days to a month or more.
See also
Byais
Kabarawan
Intus
Mead
Sima
References
Fermented drinks
Philippine alcoholic drinks
Filipino cuisine | Bais (wine) | [
"Biology"
] | 77 | [
"Fermented drinks",
"Biotechnology products"
] |
60,667,578 | https://en.wikipedia.org/wiki/Virtually%20imaged%20phased%20array | A virtually imaged phased array (VIPA) is an angular dispersive device that, like a prism or a diffraction grating, splits light into its spectral components. The device works almost independently of polarization. In contrast to prisms or regular diffraction gratings, the VIPA has a much higher angular dispersion but has a smaller free spectral range. This aspect is similar to that of an Echelle grating, since it also uses high diffraction orders. To overcome this disadvantage, the VIPA can be combined with a diffraction grating. The VIPA is a compact spectral disperser with high wavelength resolving power.
Basic mechanism
In a virtually imaged phased array, the phased array is the optical analogue of a phased array antenna at radio frequencies. Unlike a diffraction grating which can be interpreted as a real phased array, in a virtually imaged phased array the phased array is created in a virtual image. More specifically, the optical phased array is virtually formed with multiple virtual images of a light source. This is the fundamental difference from an Echelle grating, where a similar phased array is formed in the real space. The virtual images of a light source in the VIPA are automatically aligned exactly at a constant interval, which is critical for optical interference. This is an advantage of the VIPA over an Echelle grating. When the output light is observed, the virtually imaged phased array works as if light were emitted from a real phased array.
History and applications
VIPA was proposed and named by Shirasaki in 1996. Prior to the publication in the paper, a preliminary presentation was given by Shirasaki at a conference. This presentation was reported in Laser Focus World. The details of this new approach to producing angular dispersion were described in the patent. Since then, in the first ten years, the VIPA was of particular interest in the field of optical fiber communication technology. The VIPA was first applied to optical wavelength division multiplexing (WDM) and a wavelength demultiplexer was demonstrated for a channel spacing of 0.8 nm, which was a standard channel spacing at the time. Later, a much smaller channel separation of 24 pm and a 3 dB bandwidth of 6 pm were achieved by Weiner in 2005 at 1550 nm wavelength range. For another application, by utilizing the wavelength-dependent length of the light path due to the angular dispersion of the VIPA, the compensation of chromatic dispersion of fibers was studied and demonstrated (Shirasaki, 1997). The compensation was further developed for tunable systems by using adjustable mirrors or a spatial light modulator (Weiner, 2006). Using the VIPA, compensation of polarization mode dispersion was also achieved (Weiner, 2008). Furthermore, pulse shaping using the combination of a VIPA for high-resolution wavelength splitting/recombining and a SLM was demonstrated (Weiner, 2010).
A drawback of the VIPA is its limited free spectral range due to the high diffraction order. To expand the functional wavelength range, Shirasaki combined a VIPA with a regular diffraction grating in 1997 to provide a broadband two-dimensional spectral disperser. This configuration can be a high performance substitute for diffraction gratings in many grating applications. After the mid 2000s, the two-dimensional VIPA disperser has been used in various fields and devices, such as high-resolution WDM (Weiner, 2004), a laser frequency comb (Diddams, 2007), a spectrometer (Nugent-Glandorf, 2012), astrophysical instruments (Le Coarer, 2017, Bourdarot, 2018, Delboulbé, 2022, and Stacey, 2024), Brillouin spectroscopy in biomechanics (Scarcelli, 2008, Rosa, 2018, and Margueritat, 2020), other Brillouin spectroscopy (Loubeyre, 2022 and Wu, 2023), beam scanning (Ford, 2008), microscopy (Jalali, 2009), tomography imaging (Ellerbee, 2014), metrology (Bhattacharya, 2015), fiber laser (Xu, 2020), LiDAR (Fu, 2021), and surface measurement (Zhu, 2022).
Structure and operational principle
The main component of a VIPA is a glass plate whose normal is slightly tilted with respect to the input light. One side (light input side) of the glass plate is coated with a 100% reflective mirror and the other side (light output side) is coated with a highly reflective but partially transmissive mirror. The side with the 100% reflective mirror has an anti-reflection coated light entrance area, through which a light beam enters the glass plate. The input light is line-focused to a line (focal line) on the partially transmissive mirror on the light output side. A typical line-focusing lens is a cylindrical lens, which is also part of the VIPA. The light beam is diverging after the beam waist located at the line-focused position.
After the light enters the glass plate through the light entrance area, the light is reflected at the partially transmissive mirror and the 100% reflective mirror, and thus the light travels back and forth between the partially transmissive mirror and the 100% reflective mirror.
It is noted that the glass plate is tilted as a result of its slight rotation where the axis of rotation is the focal line. This rotation/tilt prevents the light from leaving the glass plate out of the light entrance area. Therefore, in order for the optical system to work as a VIPA, there is a critical minimum angle of tilt that allows the light entering through the light entrance area to return only to the 100% reflective mirror. Below this angle, the function of the VIPA is severely impaired. If the tilting angle were zero, the reflected light from the partially transmissive mirror would travel exactly in reverse and exit the glass plate through the light entrance area without being reflected by the 100% reflective mirror. In the figure, refraction at the surfaces of the glass plate was ignored for simplicity.
When the light beam is reflected each time at the partially transmissive mirror, a small portion of the light power passes through the mirror and travels away from the glass plate. For a light beam passing through the mirror after multiple reflections, the position of the line-focus can be seen in the virtual image when observed from the light output side. Therefore, this light beam travels as if it originated at a virtual light source located at the position of the line-focus and diverged from the virtual light source. The positions of the virtual light sources for all the transmitted light beams automatically align along the normal to the glass plate with a constant spacing, that is, a number of virtual light sources are superimposed to create an optical phased array. Due to the interference of all the light beams, the phased array emits a collimated light beam in one direction, which is at a wavelength dependent angle, and therefore, an angular dispersion is produced.
Wavelength resolution
Similarly to the resolving power of a diffraction grating, which is determined by the number of the illuminated grating elements and the order of diffraction, the resolving power of a VIPA is determined by the reflectivity of the back surface of the VIPA and the thickness of the glass plate. For a fixed thickness, a high reflectivity causes light to stay longer in the VIPA. This creates more virtual sources of light and thus increases the resolving power. On the other hand, with a lower reflectivity, the light in the VIPA is quickly lost, meaning fewer virtual sources of light are superimposed. This results in lower resolving power.
For large angular dispersion with high resolving power, the dimensions of the VIPA should be accurately controlled. Fine tuning of the VIPA characteristics was demonstrated by developing an elastomer-based structure (Metz, 2013).
A constant reflectivity of the partially transmissive mirror in the VIPA produces a Lorentzian power distribution when the output light is imaged onto a screen, which has a negative effect on the wavelength selectivity. This can be improved by providing the partially transmissive mirror with a linearly decreasing reflectivity. This leads to a Gaussian-like power distribution on a screen and improves the wavelength selectivity or the resolving power.
Spectral dispersion law
An analytical calculation of the VIPA was first performed by Vega and Weiner in 2003 based on the theory of plane waves and an improved model based on the Fresnel diffraction theory was developed by Xiao and Weiner in 2004.
Commercialization of the VIPA
VIPA devices have been commercialized by LightMachinery as spectral disperser devices or components with various customized design parameters.
References
Spectroscopy
Optical components
Interferometry | Virtually imaged phased array | [
"Physics",
"Chemistry",
"Materials_science",
"Technology",
"Engineering"
] | 1,824 | [
"Glass engineering and science",
"Optical components",
"Molecular physics",
"Spectrum (physical sciences)",
"Instrumental analysis",
"Spectroscopy",
"Components"
] |
60,669,845 | https://en.wikipedia.org/wiki/Hubble%20Legacy%20Field | The Hubble Legacy Field is an image of a small region of space in the constellation Fornax, containing an estimated 265,000 galaxies. The original release was composed of Hubble Space Telescope data accumulated over a 16-year period. Looking back approximately 13 billion years (between 400 and 800 million years after the Big Bang) it has been used to search for galaxies that existed at that time. The image was taken in a section of the sky with a low density of bright stars in the near-field, allowing much better viewing of dimmer, more distant objects. It builds on the data collected for the Hubble Ultra-Deep Field, the Hubble eXtreme Deep Field and the Great Observatories Origins Deep Survey.
Located southwest of Orion in the southern-hemisphere constellation Fornax, the approximately rectangular image is about 25 arcminutes to an edge. This is almost the angular diameter of a full moon viewed from Earth (which is about 31 arcminutes, or a half a degree).
The images and data release were announced on May 2, 2019, by NASA.
Planning
As with the earlier fields, this one was required to contain very little emission from our galaxy, with little Zodiacal dust. The field was also required to be in a range of declinations such that it could be observed both by southern hemisphere instruments, such as the Atacama Large Millimeter Array, and northern hemisphere ones, such as those located on Hawaii. It was ultimately decided to observe a section of the Chandra Deep Field South, due to existing deep X-ray observations from Chandra X-ray Observatory and two interesting objects already observed in the Great Observatories Origins Deep Survey sample at the same location: a redshift 5.8 galaxy and a supernova. The coordinates of the field are right ascension , declination (J2000).
Observations
The Hubble Legacy Field is composed of data from 7,500 exposures, with a total exposure time of 250 days.
Video
See also
List of deep fields
List of UDF objects (1–500)
References
External links
Scalable interactive Hubble Legacy Field. Wikisky.org
Hubble Legacy Field at HubbleSite
Hubble Space Telescope images
Physical cosmology
Sky regions
Fornax
Astronomy image articles
2019 works
2010s photographs | Hubble Legacy Field | [
"Physics",
"Astronomy"
] | 469 | [
"Theoretical physics",
"Works about astronomy",
"Astronomy image articles",
"Astrophysics",
"Constellations",
"Physical cosmology",
"Sky regions",
"Fornax",
"Astronomical sub-disciplines"
] |
60,670,137 | https://en.wikipedia.org/wiki/Thomas%20Frederick%20Hope | Thomas Frederick Hope OBE CEng (22 March 1919 – 19 May 1996) was a Sierra Leonean civil engineer, businessman, and scholar who was the general manager and chief engineer of the Guma Valley Water Company and president of the Sierra Leone Chamber of Commerce. He was onetime president of the Ecobank Transnational Incorporated and was onetime president of the Federation of West African Chambers of Commerce.
Early life and education
Thomas Frederick Hope was born on 22 March 1919 in Freetown, Sierra Leone to Creole parents, Thomas George Frederick Hope, a mechanic, and Lottie Fanny, née Elba, of Jamaican Maroon, Liberated African, and distant English descent and possibly with partial origins in Wellington Village. Thomas Frederick Hope was educated at the Government Model School in Freetown and subsequently at the Prince of Wales School.
Hope was initially attached to the General Clerical Service of the Colonial Secretary's Office and was subsequently awarded a three-year scholarship to Achimota College for the purpose of undertaking an engineering qualification to take up the role of assistant water works engineer to the Freetown City Council. He then attended the Achimota College in Ghana and proceeded to Loughborough Technical College in England, before returning to Sierra Leone and entering the Sierra Leonean civil service from 1940 to 1942.
Career and business activities
Engineering career
He was appointed as an Assistant Water Engineer in 1950 and he served as Assistant Water Engineer in 1951 and was later promoted to the role of City Water Engineer in 1955. He served as Acting general manager of the Guma Valley Water Company in 1961 and was promoted to general manager of the Guma Valley Water Company in 1962 and later general manager and Engineer-in-Chief in 1963. He served as general manager and Chief Engineer of the Guma Valley Water Company from 1963 until his retirement in May 1976.
Business and civil activities
Following his retirement in May 1976, Hope was appointed as the Chief Consultant of the Engineering and Management Consultancy Ltd (ENGCON) in Freetown, Sierra Leone and was a consultant to the African Development Bank in Abidjan, Ivory Coast.
Hope served as President of the Sierra Leone Chamber of Commerce from 1952 to 1978 and was at one-time a member of the Sierra Leone Employers Federation. He had an active interest in the development of sports in Sierra Leone and served as chairman of the Sierra Leone Amateur Athletic Association and was a member of the Sierra Leone Sports Council from 1951 to 1970 which he eventually led as president. He served as President of the Sierra Leone Olympic and Overseas Games Committee from 1963. He was also an active member and President of the Sierra Leone Rotary Club and was an Administrative Adviser to Group F. of Rotary International.
Hope also served as chairman and director on the boards of several well-known multi-national companies operating in Sierra Leone and West Africa more broadly.
Achievements
Hope held the DSc (Honoris Causa) of the University of Sierra Leone. He was awarded an M.B.E. in 1961 and an O.B.E. in 1970.
Personal life
Thomas Hope married Christine Ellenora Akaje-Macauley, a daughter of William Akaje-Macauley, a Sierra Leonean lawyer on 12 August 1953 in Freetown, Sierra Leone. Thomas Hope and Christine Hope had four children including Andre Thomas Hope, a lawyer and businessman who serves as a non-executive director of Ecobank Sierra Leone, Ann-Lise Hope, Anthea Abayomi-Cole, née Hope, and Anthony Hope.
Thomas Hope died in a London Hospital in London, England at the age of 77 in 1996.
Sources
Sierra Leone Year Book
Who's Who
West Africa
References
1919 births
1996 deaths
People of Sierra Leone Creole descent
Sierra Leonean people of Caribbean descent
Sierra Leonean people of British descent
Sierra Leonean people of Jamaican Maroon descent
Sierra Leonean businessmen
Civil engineers
Sierra Leonean Christians
People from Freetown
Alumni of Achimota School
Sierra Leonean engineers
20th-century engineers
Sierra Leonean expatriates in the United Kingdom | Thomas Frederick Hope | [
"Engineering"
] | 797 | [
"Civil engineering",
"Civil engineers"
] |
60,670,327 | https://en.wikipedia.org/wiki/Bilirubin%20glucuronide | Bilirubin glucuronide is a water-soluble reaction intermediate over the process of conjugation of indirect bilirubin. Bilirubin glucuronide itself belongs to the category of conjugated bilirubin along with bilirubin di-glucuronide. However, only the latter one is primarily excreted into the bile in the normal setting.
Upon macrophages spot and phagocytize the effete Red Blood Corpuscles containing hemoglobin, unconjugated bilirubin is discharged from macrophages into the blood plasma. Most often, the free and water-insoluble unconjugated bilirubin which has an internal hydrodren bonding will bind to albumin and, to a much lesser extent, high density lipoprotein in order to decrease its hydrophobicity and to limit the probability of unnecessary contact with other tissues and keep bilirubin in the vascular space from traversing to extravascular space including brain, and from ending up increasing glomerular filtration. Nevertheless, there is still a little portion of indirect bilirubins stays free-of-bound. Free unconjugated bilirubin can poison the cerebrum.
Finally, albumin leads the indirect bilirubin to the liver. In the liver sinusoid, albumin disassociates with the indirect bilirubin and returns to the circulation while the hepatocyte transfers the indirect bilirubin to ligandin and glucuronide conjugates the indirect bilirubin in the endoplasmic reticulum by disrupting unconjugated bilirubin's internal hydrogen bonding, which is the thing that makes indirect bilirubin having the property of eternal half-elimination life and insoluble in water, and by attaching two molecules of glucuronic acid to it in a two step process. The reaction is a transfer of two glucuronic acid groups including UDP glucuronic acid sequentially to the propionic acid groups of the bilirubin, primarily catalyzed by UGT1A1. In greater detail about this reaction, a glucuronosyl moiety is conjugated to one of the propionic acid side chains, located on the C8 and C12 carbons of the two central pyrrole rings of bilirubin.
When the first step is completely done, the substrate bilirubin glucuronide (also known as mono-glucuronide) is born at this stage and is water-soluble and readily excreted in bile. Thereafter, so long as the second step of attachment of the other glucuronic acid to it succeeds (officially called "re-glucuronidated"), the substrate bilirubin glucuronide will turn into bilirubin di-glucuronide (8,12-diglucuronide) and be excreted into bile canaliculi by way of C-MOAT and MRP2 as normal human bile along with a little amount of unconjugated bilirubin as much as only 1 to 4 percent of total pigments in normal bile. That means up to 96%-99% of bilirubin in the bile are conjugated.
Normally, there is just a little conjugated bilirubin escapes into the general circulation. Nonetheless, in the setting of severe liver disease, a significantly greater number of conjugated bilirubin will leak into circulation and then dissolve into the blood and thereby filtered by the kidney, and only a part of the leaked conjugated bilirubin will be re-absorbed in the renal tubules, the remainder will be present in the urine making it dark-colored.
Clinical significance
The clinical significance of bilirubin glucuronide is involved in many conditions. Drugs that inhibit the activities of the components involved in bilirubin metabolism can give rise to accumulation of bilirubin in the blood. In comparison, conjugation of some drugs is also usually impaired if the liver cannot normally metabolize indirect bilirubin.
Renal
When excretion of bilirubin glucuronide by the kidney is detected in the urine through urine examination, meaning that a conspicuous amount of conjugated bilirubin is present and circulating in the blood.
Dubin–Johnson syndrome
In Dubin–Johnson syndrome, impaired biliary excretion of bilirubin glucuronide is due to a mutation in the canalicular multiple drug-resistance protein 2 (MRP2). A darkly pigmented liver is due to polymerized epinephrine metabolites, not bilirubin.
Liver failure or hepatitis
If it is the liver that cannot effectively transfer the indirect bilirubin into bilirubin glucuronide and further into bilirubin di-glucuronide, the consequence will be hyperbilirubinemia or intrahepatic (or hepatocellular) jaundice.
Moreover, the unconjugated hyperbilirubinemia arises in case the components of liver transfer the indirect bilirubin into bilirubin glucuronide in the rate slower than they should be. This condition is associated with either decreased uptake of bilirubin into hepatocytes (Rotor syndrome) or defective intracellular protein binding.
In similar fashion, the conjugated hyperbilirubinemia emerges in case the components of the liver have difficulty turning bilirubin glucuronide into bilirubin di-glucuronide. Note that biliary duct blockage can also lead to conjugated hyperbilirubinemia but the pathophysiology is that backflow of bilirubin di-glucuronide with little indirect bilirubin and bilirubin glucuronide from bile duct through liver into blood plasma. These conditions are associated with either defective intracellular protein binding (for the second time) or disturbed secretion into the bile canaliculi (Dubin–Johnson syndrome).
Liver failure and hepatitis are the most etiological in liver-genesis hyperbilirubinemia. In case of hyperbilirubinemia due to intrahepatic or extrahepatic bile ducts blockage, e.g. gallstone, the name is given as Post-hepatic (or obstructive) jaundice.
Bilirubin concentration is not a sensitive early indicator of liver diseases as the liver may have reserved its capacity in removal of bilirubin to save energy and unreserved the previously reserved capacity when encountering a sudden rise of unconjugated bilirubin. In short, there is still a chance for an ill liver to get rid of excessive unconjugated bilirubin in the blood plasma, displaying a total bilirubin level that is within normal reference range.
Crigler Najjar disease
In Crigler Najjar disease, there is an inherited deficiency of glucuronyl transferase resulting in high concentrations of unconjugated bilirubin appear in the plasma. Furthermore, those affected may develop kernicterus (deposits of pigment in the brain) that can cause nerve degeneration.
Gilbert's syndrome
In Gilbert's syndrome, glucuronyl transferase activity is reduced by approximately 70%, leading to mild accumulation of unconjugated bilirubin in the plasma.
Neonate jaundice
At birth, infants don't develop enough ability to conjugate bilirubin. Up to 8% to 11% neonates will develop hyperbilirubinemia in the first week of their lives.
Hemolytic jaundice
In jaundice owing to hemolysis (prehepatic, or hemolytic, jaundice), the pathophysiology is that overproduction of bilirubin from the extravascular or intravascular hemolysis overwhelms the capacity of the liver to excrete it. The bilirubin present in the plasma is largely unconjugated in this setting as they haven't been taken up and conjugated by the liver. In this case, total serum bilirubin increases while the ratio of direct bilirubin to indirect bilirubin remains 96 to 4 as up to 96%-99% of bilirubin in the bile are conjugated mentioned above.
Brain damage
Although there were some studies that showed an inverse correlation between serum bilirubin level and prevalences of ischemic coronary artery disease, cancer mortality, or colorectal cancer in general population, the potential benefits of the chemopreventive function of bilirubin and their causative relations haven't been proved.
Notes
References
Metabolism
Hematology | Bilirubin glucuronide | [
"Chemistry",
"Biology"
] | 1,895 | [
"Biochemistry",
"Metabolism",
"Cellular processes"
] |
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