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63,570,432 | https://en.wikipedia.org/wiki/Scherzer%27s%20theorem | Scherzer's theorem is a theorem in the field of electron microscopy. It states that there is a limit of resolution for electronic lenses because of unavoidable aberrations.
German physicist Otto Scherzer found in 1936 that the electromagnetic lenses, which are used in electron microscopes to focus the electron beam, entail unavoidable imaging errors. These aberrations are of spherical and chromatic nature, that is, the spherical aberration coefficient Cs and the chromatic aberration coefficient Cc are always positive.
Scherzer solved the system of Laplace equations for electromagnetic potentials assuming the following conditions:
electromagnetic fields are rotationally symmetric,
electromagnetic fields are static,
there are no space charges.
He showed that under these conditions the aberrations that emerge degrade the resolution of an electron microscope up to one hundred times the wavelength of the electron. He concluded that the aberrations cannot be fixed with a combination of rotationally symmetrical lenses.
In his original paper, Scherzer summarized: "Chromatic and spherical aberration are unavoidable errors of the space charge-free electron lens. In principle, distortion (strain and twist) and (all types of) coma can be eliminated. Due to the inevitability of spherical aberration, there is a practical, but not a fundamental, limit to the resolving power of the electron microscope."
The resolution limit provided by Scherzer's theorem can be overcome by breaking one of the above mentioned three conditions. Giving up rotational symmetry in electronic lenses helps in correcting spherical aberrations. A correction of the chromatic aberration can be achieved with time-dependent, ie non-static, electromagnetic fields (for example in particle accelerators).
Scherzer himself experimented with space charges (eg with charged foils), dynamic lenses, and combinations of lenses and mirrors to minimize aberrations in electron microscopes.
References
Electron microscopy | Scherzer's theorem | [
"Chemistry"
] | 397 | [
"Electron",
"Electron microscopy",
"Microscopy"
] |
63,571,124 | https://en.wikipedia.org/wiki/Alais%20meteorite | Alais or Allais is the first carbonaceous chondrite meteorite identified. It fell near Alès in 1806 in multiple fragments which together weighed , although only remains. The meteorite contains a number of elements in similar proportions to the Solar System in its primordial state. It also contains organic compounds and water. It has proved to be one of the most important meteorites discovered in France.
History
At 17:00 on 15 March 1806, two detonations were heard near Alès in Gard, France. Shortly afterwards, two soft black stones were discovered in the villages of Saint-Étienne-de-l'Olm and Castelnau-Valence, weighing and respectively. The fragments were collected by people who observed the impact and given to two scientists that lived locally. The meteorite was analysed by Louis Jacques Thénard, who published a study in 1807, showing that it had a high carbon content. It was initially doubted that the fragments were of non-terrestrial origins as their attributes were markedly different to existing meteorites. However, it was increasingly realised that this was a new, albeit rare, type of meteorite. The meteorite is also known as Valence.
Curation and distribution
As an early fall (soon after the consensus that meteorites were real, extraterrestrial phenomenon), Alais has largely been dispersed. Few samples have been preserved, less than Orgueil, but more than Tonk and particularly Revelstoke.
Source: Grady, M. M. Catalogue of Meteorites, 5th Edition, Cambridge University Press
Description
Overview
The Alais meteorite is one of the most important meteorites in France. It is black with loose friable textures with a low density of less than . Originally consisting of fragments that together weighed , it has been subject to substantial scientific examination and currently only remains. A fragment, weighing is held by the National Museum of Natural History, France.
Composition and classification
The meteorite is one of five known meteorites belonging to the CI chondrite group. This group is remarkable for having an elemental distribution that has the strongest similarity to that of the solar nebula. Except for certain volatile elements, like carbon, hydrogen, oxygen, nitrogen and the noble gases, which are not present in the meteorites in the same proportions, the ratios of the elements are very similar. The meteorite contains cubanite, dolomite, fosterite, pyrrhotite and zircon amongst other minerals.
Origin of life controversy
The meteorite has been at the centre of controversial claims about an extraterrestrial origin of life since the discovery of organic matter on the meteorite by Jöns Jacob Berzelius. Organic compounds, amino acids and water have been found in the meteorite. However, studies differentiate between organic and biological matter, the latter not being present.
See also
Glossary of meteoritics
References
Citations
Bibliography
Astrobiology
Meteorites found in France
1806 in France | Alais meteorite | [
"Astronomy",
"Biology"
] | 598 | [
"Origin of life",
"Speculative evolution",
"Astrobiology",
"Biological hypotheses",
"Astronomical sub-disciplines"
] |
63,572,008 | https://en.wikipedia.org/wiki/Thermodynamics%20and%20an%20Introduction%20to%20Thermostatistics | Thermodynamics and an Introduction to Thermostatistics is a textbook written by Herbert Callen that explains the basics of classical thermodynamics and discusses advanced topics in both classical and quantum frameworks. It covers the subject in an abstract and rigorous manner and contains discussions of applications. The textbook contains three parts, each building upon the previous. The first edition was published in 1960 and a second followed in 1985.
Overview
The first part of the book starts by presenting the problem thermodynamics is trying to solve, and provides the postulates on which thermodynamics is founded. It then develops upon this foundation to discuss reversible processes, heat engines, thermodynamics potentials, Maxwell's relations, stability of thermodynamics systems, and first-order phase transitions. As the author lays down the basics of thermodynamics, he then goes to discuss more advanced topics such as critical phenomena and irreversible processes.
The second part of the text presents the foundations of classical statistical mechanics. The concept of Boltzmann's entropy is introduced and used to describe the Einstein model, the two-state system, and the polymer model. Afterwards, the different statistical ensembles are discussed from which the thermodynamics potentials are derived. Quantum fluids and fluctuations are also discussed.
The last part of the text is a brief discussion on symmetry and the conceptual foundations of thermostatistics. In the final chapter, Callen advances his thesis that the symmetries of the fundamental laws of physics underlie the very foundations of thermodynamics and seeks to illuminate the crucial role thermodynamics plays in science.
Callen advises that a one-semester course for advanced undergraduates should cover the first seven chapters plus chapters 15 and 16 if time permits.
Second edition
Background
The second edition provides a descriptive account of the thermodynamics of critical phenomena, which progressed dramatically in the 1960s and 1970s. Drawing on feedback from students and instructors, Callen improved many explanations, explicitly solved examples, and added many exercises, many of which have complete or partial answers. He also provided an introduction to statistical mechanics with an emphasis on the core principles rather than the applications. However, he sought to neither separate thermodynamics and statistical mechanics completely nor subsume the former under the latter under the banner of "thermal physics." Indeed, thermal physics courses often emphasizes statistical mechanics at the expense of thermodynamics, despite its importance for industry, as a survey of business leaders conducted by the American Physical Society in 1971 suggested. Callen observed that thermodynamics had subsequently been de-emphasized.
Table of Contents
Part I: General Principles of Classical Thermodynamics
Introduction: The Nature of Thermodynamics and the Basis of Thermostatistics
Chapter 1: The Problem and the Postulates
Chapter 2: The Conditions of Equilibrium
Chapter 3: Some Formal Relationships, and Sample Systems
Chapter 4: Reversible Processes and the Maximum Work Theorem
Chapter 5: Alternative Formulations and Legendre Transformations
Chapter 6: The Extremum Principle in the Legendre Transformed Representations
Chapter 7: Maxwell Relations
Chapter 8: Stability of Thermodynamic Systems
Chapter 9: First-order Phase Transitions
Chapter 10: Critical Phenomena
Chapter 11: The Nernst Postulate
Chapter 12: Summary of Principles for General Systems
Chapter 13: Properties of Materials
Chapter 14: Irreversible Thermodynamics
Part II: Statistical Mechanics
Chapter 15: Statistical Mechanics in the Entropy Representation
Chapter 16: The Canonical Formalism; Statistical Mechanics in Helmholtz Representation
Chapter 17: Entropy and Disorder; Generalized Canonical Formulations
Chapter 18: Quantum Fluids
Chapter 19: Fluctuations
Chapter 20: Variational Properties, Perturbation Expansions, and Mean Field Theory
Part III: Foundations
Chapter 21: Postlude: Symmetry and the Conceptual Foundations of Thermostatistics
Appendix A: Some Relations Involving Partial Derivatives
Appendix B: Magnetic Systems
General References
Index
Reception
Robert B. Griffiths, a specialist in thermodynamics and statistical mechanics at the Carnegie Mellon University, commented that both editions of this book presents clearly and concisely the core of thermodynamics within the first eight chapters. At the time of writing (1987), Griffiths knew of books that explained the principles of thermodynamics, but Callen's was had the best presentation of the material. He believed Callen offered a pedagogical, if abrupt, treatment of the subject. His book begins in an abstract manner, assuming the existence and properties of entropy and derive the consequences for various processes of interest rather than through heat engines and thermodynamic cycles or by statistical mechanics and Boltzmann's entropy formula . However, he argued that Callen's treatment of critical phenomena (Chapter 10) contains some technical flaws. Callen thought that classical analysis had broken down. But Griffiths wrote that the problem lies not in the breakdown of thermodynamics but rather the Taylor-expansion of thermodynamic quantities, and that precise expressions of the functions appearing in a fundamental relation should be determined by statistical mechanics and experiments, not thermodynamics. Nevertheless, Griffiths still believed this book to be an excellent resource for learning the basics of thermodynamics.
According to L.C. Scott, who studied statistical mechanics and biophysics at Oklahoma State University, Thermodynamics and an Introduction to Thermostatistics is a popular textbook that begins with some basic postulates based on intuitive classical, empirical, and macroscopic arguments. He found that it is remarkable for the whole edifice of classical thermodynamics to follow from just a few basic assumptions. However, Scott preferred the discussion of temperature in Heat and Thermodynamics by Mark W. Zemansky and Richard H. Dittman because it is based on thermometry and forces students to contemplate the empirical basis of concept of temperature, leaving aside the molecular basis of heat. He argued that such an approach yields greater appreciation for the meaning of temperature and its statistical-mechanical basis which students will encounter later. In contrast, Callen's book does not mention temperature till Chapter 2, where Callen defines temperature as the reciprocal of the derivative of entropy with respect to internal energy then shows, using the postulates, that this definition is consistent with our intuition. While Zemansky and Dittman cover the first law of thermodynamics empirically, Callen simply assumes the existence of the internal energy function the invokes the conservative nature of inter-atomic forces. Whereas Zemansky and Dittman treated the second law of thermodynamics using heat engines and simply state the Clausius and Kelvin formulations of it, in Callen's book, the second law is contained within the postulates. Scott was unsure which approach is more understandable for students. In general, Zemansky and Dittman employed an empirical approach while that of Callen is deductive. Scott opined that Zemansky and Dittman's book is more suitable for beginning students while Callen's is more appropriate for an advanced course or as a reference.
Editions
See also
List of textbooks in thermodynamics and statistical mechanics
List of textbooks on classical mechanics and quantum mechanics
References
1960 books
1985 books
Physics textbooks
Thermodynamics literature | Thermodynamics and an Introduction to Thermostatistics | [
"Physics",
"Chemistry"
] | 1,512 | [
"Thermodynamics literature",
"Thermodynamics"
] |
63,572,622 | https://en.wikipedia.org/wiki/The%20MICCAI%20Society | The MICCAI Society is a professional organization for scientists in the areas of Medical Image Computing and Computer Assisted Interventions. Due to the multidisciplinary nature of these fields, the society brings together researchers from several scientific disciplines. including computer science, robotics, physics, and medicine. The society is best known for its annual flagship event, The MICCAI Conference, which facilitates the publication and presentation of original research on MICCAI-related topics. However, the society provides endorsements and sponsorships for several scientific events each year.
History
In 1998, three international conferences: Visualization in Biomedical Computing (VBC), Computer Vision and Virtual Reality in Robotics and Medicine (CVRMed), and Medical Robotics and Computer Assisted Surgery (MRCAS) merged into a single conference entitled "The International Conference on Medical Image Computing and Computer Assisted Interventions" (abbreviated MICCAI) with its first edition in Boston. The MICCAI Society was founded in 2004 by several active members of this research community and former chairs of the MICCAI conference. In 2009, the society introduced the "MICCAI Fellow" award to recognize senior members who had made substantial contributions to the MICCAI community. 12 fellows were elected in 2009 and three additional fellows are elected each year. New MICCAI Fellows are announced each year at the Annual MICCAI Conference. Since 2012, the society is involved in several events each year outside of the annual conference through endorsements and/or sponsorships. These include a number of smaller international conferences, MICCAI-focused workshop sessions at related conferences, and educational programs such as "summer schools".
Research focus
Medical Image Computing
Medical Image Computing (the "MIC" in MICCAI) is the field of study involving the application of image processing and computer vision to medical imaging. The goals of medical image computing tasks are diverse, but some common examples are computer-aided diagnosis, image segmentation of anatomical structures and/or abnormalities, and the registration or "alignment" of medical images acquired through different means or at different points in time.
Computer Assisted Interventions
Computer Assisted Interventions (the "CAI" in MICCAI) is the field of study concerned with the use of computational tools in medical interventions. Prominent examples of computer aided interventions currently in widespread use include image guided biopsy and robot-assisted surgery. Integral to this research area is effective human-computer interaction and user interface design.
Subgroups
Within the MICCAI community, a number of organizations have emerged to represent and advocate for certain populations of MICCAI researchers. Among these are the MICCAI Student Board and the Women in MICCAI Committee.
MICCAI Student Board
The MICCAI Student Board began in 2010 when MICCAI initiated its social media presence by creating a facebook group. This effort was championed by student researchers who used the group to organize events specifically for students at the 2011 and 2012 annual conferences. After the 2012 event, the MICCAI board of directors formally recognized the MICCAI student board as a part of the society and began providing support for the student board's annual events.
Women in MICCAI Committee
The Women in MICCAI Committee began as a series of networking sessions for female researchers within the medical image analysis research community during the 2015 MICCAI conference and the 2016 IEEE International Symposium on Biomedical Imaging. In October 2016, the MICCAI board of directors approved a measure to create the "Women in MICCAI Committee" with the goal of strengthening the representation of female scientists in this research area.
Since its inception, the Women in MICCAI Committee has continued to organize networking sessions in conjunction with MICCAI events. It also developed and maintains several online platforms for discussion on social media. The committee is the primary interface between the MICCAI board of directors and the community of women researchers in MICCAI.
Annual MICCAI conference
Conference format
MICCAI conferences are typically scheduled for five days, of which the first and last days set aside for satellite events consisting of tutorials, workshops, and challenges. Those include the Brain lesion workshop (BrainLes), the Workshop on Interpretability of Machine Intelligence in Medical Image Computing (iMIMIC), the Workshop on Domain Adaptation and Representation Transfer (DART), the International Workshop on Multimodal Brain Image Analysis (MBIA), and others. The main conference includes invited presentations, panel discussions, and podium and poster presentations of original research papers which are published by Springer Nature as conference proceedings.
Past MICCAI conferences
Upcoming MICCAI conferences
Publications
The MICCAI conference proceedings consist of full-length papers which undergo comprehensive peer review. Since even before the merger of the CVRMed, MRCAS, and VBC conferences (see History), the proceedings of the annual conference have been published by Springer Nature as part of the Lecture Notes in Computer Science (LNCS) series.
In addition to the proceedings of the annual conference, MICCAI officially partners with two peer reviewed scientific journals: "Medical Image Analysis" published by Elsevier and "The International Journal of Computer Assisted Radiology and Surgery" (IJCARS) published by Springer Nature. These journals loosely correspond to the "MIC" and "CAI" focuses of the MICCAI Society respectively, but they have substantial overlap in subject matter.
The MICCAI Society also partners with Elsevier to develop a series of books on MICCAI-related research, written by scientists in the MICCAI research community. , nine books have been published in this series
See also
Robot-assisted surgery
Computer vision
Conference on Computer Vision and Pattern Recognition
International Conference on Computer Vision
European Conference on Computer Vision
Institute of Electrical and Electronics Engineers
International Society for Computer Aided Surgery
References
External links
The MICCAI Society Website
Computer science-related professional associations
Computer science organizations
Computing in medical imaging
Medical imaging organizations
Medical technology organizations
Health informatics | The MICCAI Society | [
"Technology",
"Biology"
] | 1,182 | [
"Computer science organizations",
"Medical technology organizations",
"Health informatics",
"Computer science",
"Medical technology"
] |
63,576,142 | https://en.wikipedia.org/wiki/Cryptic%20self-incompatibility | Cryptic self-incompatibility (CSI) is the botanical expression that's used to describe a weakened self-incompatibility (SI) system. CSI is one expression of a mixed mating system in flowering plants. Both SI and CSI are traits that increase the frequency of fertilization of ovules by outcross pollen, as opposed to self-pollen.
Background
Although the evident product of more outcrossing is a mutual result among SI systems, CSI should not be mistaken for any other form of true SI, such as common gametophytic SI or sporophytic SI. Robert Bowman outlined the distinction when he posited that cryptic SI allows for full seed set via self-pollination when outcross pollen is limited or absent. CSI has been observed to be a significant benefit to flowering plants as it allows plants to avoid inbreeding depression in their offspring when outcross pollen is available. Because this breeding method allows for full seed set it is thought of as another form of reproductive assurance. The contemporary understanding of this breeding system, which involves self-pollen discrimination, outlines the "best-of-both-worlds" hypothesis that was described by Bowman in 1987; and later refined and given a name by Becerra and Lloyd in 1992.
CSI was first described by A.J. Bateman in 1956 as a weak incompatibility system that results in a significantly higher proportion of seeds set by outcross pollen within an individual as opposed to self-pollen, when both types are present on the stigma in equal amounts.
Since the first documented observation of CSI our understanding of how these systems work has undergone several refinements as more studies are conducted. There are multiple known mechanisms through which CSI acts but it is commonly defined as a form of parental selection that occurs post-pollination. Although not all mechanisms of CSI acts have been described.
Mechanisms
Pollen competition
This form of CSI is achieved by having differential pollen tube growth. It has been observed that, on average, the pollen tubes from pollen that is genetically similar to the stigma will grow more slowly than the pollen tubes from pollen that is not related to the style, known as outcross pollen. CSI occurs by stylar discrimination, such that outcross pollen tubes are favored over self pollen tubes based on differential pollen-tube growth, resulting in increased outcrossing frequency as pollen load size increases.
Pollen tube attrition
Pollen tube attrition is the failure of a pollen tube that is caused by inhibiting tube growth before fertilization can occur. This phenomenon is another way through which CSI can act. This is accomplished by failing a higher proportion of self-pollen tubes which will end up favoring fertilization by outcross pollen. This type of stylar inhibition within flowering plants, which are normally self-compatible, are known to result in mixed mating systems.
References
Plant reproduction | Cryptic self-incompatibility | [
"Biology"
] | 582 | [
"Behavior",
"Plant reproduction",
"Plants",
"Reproduction"
] |
63,576,316 | https://en.wikipedia.org/wiki/Trace%20metal%20stable%20isotope%20biogeochemistry | Trace metal stable isotope biogeochemistry is the study of the distribution and relative abundances of trace metal isotopes in order to better understand the biological, geological, and chemical processes occurring in an environment. Trace metals are elements such as iron, magnesium, copper, and zinc that occur at low levels in the environment. Trace metals are critically important in biology and are involved in many processes that allow organisms to grow and generate energy. In addition, trace metals are constituents of numerous rocks and minerals, thus serving as an important component of the geosphere. Both stable and radioactive isotopes of trace metals exist, but this article focuses on those that are stable. Isotopic variations of trace metals in samples are used as isotopic fingerprints to elucidate the processes occurring in an environment and answer questions relating to biology, geochemistry, and medicine.
Isotope notation
In order to study trace metal stable isotope biogeochemistry, it is necessary to compare the relative abundances of isotopes of trace metals in a given biological, geological, or chemical pool to a standard (discussed individually for each isotope system below) and monitor how those relative abundances change as a result of various biogeochemical processes. Conventional notations used to mathematically describe isotope abundances, as exemplified here for 56Fe, include the isotope ratio (56R), fractional abundance (56F) and delta notation (δ56Fe). Furthermore, as different biogeochemical processes vary the relative abundances of the isotopes of a given trace metal, different reaction pools or substances will become enriched or depleted in specific isotopes. This partial separation of isotopes between different pools is termed isotope fractionation, and is mathematically described by fractionation factors α or ε (which express the difference in isotope ratio between two pools), or by "cap delta" (Δ; the difference between two δ values). For a more complete description of these notations, see the isotope notation section in Hydrogen isotope biogeochemistry.
Naturally occurring trace metal isotope variations and fractionations
In nature, variations in isotopic ratios of trace metals on the order of a few tenths to several ‰ are observed within and across diverse environments spanning the geosphere, hydrosphere and biosphere. A complete understanding of all processes that fractionate trace metal isotopes is presently lacking, but in general, isotopes of trace metals are fractionated during various chemical and biological processes due to kinetic and equilibrium isotope effects.
Geochemical fractionations
Certain isotopes of trace metals are preferentially oxidized or reduced; thus, transitions between redox species of the metal ions (e.g., Fe2+ → Fe3+) are fractionating, resulting in different isotopic compositions between the different redox pools in the environment. Additionally, at high temperatures, metals ions can evaporate (and subsequently condense upon cooling), and the relative differences in isotope masses of a given heavy metal leads to fractionation during these evaporation and condensation processes. Diffusion of isotopes through a solution or material can also result in fractionations, as the lighter mass isotopes are able to diffuse at a faster rate. Additionally, isotopes can have slight variations in their solubility and other chemical and physical properties, which can also drive fractionation.
Biological fractionations
In sediments, oceans, and rivers, distinct trace metal isotope ratios exist due to biological processes such as metal ion uptake and abiotic processes such as adsorption to particulate matter that preferentially remove certain isotopes. The trace metal isotopic composition of a given organism results from a combination of the isotopic compositions of source material (i.e., food and water) and any fractionations imparted during metal ion uptake, translocation and processing inside cells.
Applications of trace metal isotope ratios
Stable isotope ratios of trace metals can be used to answer a variety of questions spanning diverse fields, including oceanography, geochemistry, biology, medicine, anthropology and astronomy. In addition to their modern applications, trace metal isotopic compositions can provide insight into ancient biogeochemical processes operated on Earth. These signatures arise because the processes that form and modify samples are recorded in the trace metal isotopic compositions of the samples. By analyzing and understanding trace metal isotopic compositions in biological, chemical or geological materials, one can answer questions such as the sources of nutrients for phytoplankton in the ocean, processes that drove the formation of geologic structures, the diets of modern or ancient organisms, and accretionary processes that took place in the early Solar System. Trace metal stable isotope biogeochemistry is still an emerging field, yet each trace metal isotope system has clear, powerful applications to diverse and important questions. Important heavy metal isotope systems are discussed (in order of increasing atomic mass) in the proceeding sections.
Iron
Stable isotopes and natural abundances
Naturally occurring iron has four stable isotopes, 54Fe, 56Fe, 57Fe, and 58Fe.
Stable iron isotopes are described as the relative abundance of each of the stable isotopes with respect to 54Fe. The standard for iron is elemental iron, IRMM-014, and it is distributed by the Institute for Reference Materials and Measurement. The delta value is compared to this standard, and is defined as:
Delta values are often reported as per mil values (‰), or part-per-thousand differences from the standard. Iron isotopic fractionation is also commonly described in units of per mil per atomic mass unit.
In many cases, the δ56Fe value can be related to the δ57Fe and δ58Fe values through mass-dependent fractionation:
Chemistry
One of the most prevalent features of iron chemistry is its redox chemistry. Iron has three oxidation states: metallic iron (Fe0), ferrous iron (Fe2+), and ferric iron (Fe3+). Ferrous iron is the reduced form of iron, and ferric iron is the oxidized form of iron. In the presence of oxygen, ferrous iron is oxidized to ferric iron, thus ferric iron is the dominant redox state of iron at Earth's surface conditions. However, ferrous iron is the dominant redox state below the surface at depth. Because of this redox chemistry, iron can act as either an electron donor or receptor, making it a metabolically useful species.
Each form of iron has a specific distribution of electrons (i.e., electron configuration), tabulated below:
Equilibrium Isotope Fractionation
Variations in iron isotopes are caused by a number of chemical processes which result in the preferential incorporation of certain isotopes of iron into certain phases. Many of the chemical processes which fractionate iron are not well understood and are still being studied. The most well-documented chemical processes which fractionate iron isotopes relate to its redox chemistry, the evaporation and condensation of iron, and the diffusion of dissolved iron through systems. These processes are described in more detail below.
Fractionation as a result of redox chemistry
To first order, reduced iron favors isotopically light iron and oxidized iron favors isotopically heavy iron. This effect has been studied in regards to the abiotic oxidation of Fe2+ to Fe3+, which results in fractionation. The mineral ferrihydrite, which forms in acidic aquatic conditions, is precipitated via the oxidation of aqueous Fe2+ to Fe3+. Precipitated ferrihydrite has been found to be enriched in the heavy isotopes by 0.45‰ per atomic mass unit with respect to the starting material. This indicates that heavier iron isotopes are preferentially precipitated as a result of oxidizing processes.
Theoretical calculations in combination with experimental data have also aimed to quantify the fractionation between Fe(III)aq and Fe(II)aq in HCl. Based on modeling, the fractionation factor between the two species is temperature dependent:
Fractionation as a result of evaporation and condensation
Evaporation and condensation can give rise to both kinetic and equilibrium isotope effects. While equilibrium mass fractionation is present evaporation and condensation, it is negligible compared to kinetic effects. During condensation, the condensate is enriched in the light isotope, whereas in evaporation, the gas phase is enriched in the light isotope. Using the kinetic theory of gases, for 56Fe/54Fe, a fractionation factor of α = 1.01835 for the evaporation of a pool containing equimolar amounts of 56Fe and 54Fe. In evaporation experiments, the evaporation of FeO at 1,823 K gave a fractionation factor of α = 1.01877. Presently, there have been no experimental attempts to determine the 56Fe/54Fe fractionation factor of condensation.
Fractionation as a result of diffusion
Kinetic fractionation of dissolved iron occurs as a result of diffusion. When isotopes diffuse, the lower mass isotopes diffuse more quickly than the heavier isotopes, resulting in fractionation. This difference in diffusion rates has been approximated as:
In this equation, D1 and D2 are the diffusivities of the isotopes, m1 and m2 are the masses of the isotopes, and β, which can vary between 0 and 0.5, depending on the system. More work is required to fully understand fractionation as a result of diffusion, studies of diffusion of iron on metal have consistently given β values of approximately 0.25. Iron diffusion between silicate melts and basaltic/rhyolitic melts have given lower β values (~0.030). In aqueous environments, a β value of 0.0025 has been obtained.
Fractionation as a result of phase partitioning
There may be equilibrium fractionation between coexisting minerals. This would be particularly relevant when considering the formation of planetary bodies early in the solar system. Experiments have aimed to simulate the formation of the Earth at high temperatures using a platinum-iron alloy and an analog for the silicate earth at 1,500 °C. However, the observed fractionation was very small, less than 0.2‰ per atomic mass unit. More experimental work is needed to fully understand this effect.
Biology
In biology, iron plays a number of roles. Iron is widespread in most living organisms and is essential for their function. In microbes, iron redox chemistry is utilized as an electron donor or receptor in microbial metabolism, allowing microbes to generate energy. In the oceans, iron is essential for the growth and survival of phytoplankton, which use iron to fix nitrogen. Iron is also important in plants, given that they need iron to transfer electrons during photosynthesis. Finally, in animals, iron plays many roles, however, its most essential function is to transport oxygen in the bloodstream throughout the body. Thus, iron undergoes many biological processes, each of which have variations in which isotopes of iron they preferentially use. While iron isotopic fractionations are observed in many organisms, they are still not well understood. Improvements in the understanding the iron isotope fractionations observed in biology will enable the development of a more complete knowledge of the enzymatic, metabolic, and other biologic pathways in different organisms. Below, the known iron isotopic variations for different classes of organisms are described.
Iron reducing bacteria
Iron reducing bacteria reduce ferric iron to ferrous iron under anaerobic conditions. One of the first studies that studied iron fractionation in iron-reducing bacteria studied the bacterium Shewanella algae. S. algae was grown on a ferrihydrite substrate, and was then allowed to reduce iron. The study found that S. algae preferentially reduced 54Fe over 56Fe, with a δ56/54Fe value of -1.3‰.
More recent experiments have studied the bacterium Shewanella putrefaciens and its reduction of Fe(III) in goethite. These studies have found δ56/54Fe values of -1.2‰ relative to the goethite. The kinetics of this fractionation were also studied in this experiment, and it was suggested that the iron isotope fractionation is likely related to the kinetics of the electron transfer step.
Most studies of other iron reducing bacteria have found δ56/54Fe values of approximately -1.3‰. At high Fe(III) reduction rates, δ56/54Fe values of -2 – -3‰ relative to the substrate have been observed. The study of iron isotopes in iron reducing bacteria enable the development of an improved understanding regarding the metabolic processes operating in these organisms.
Iron oxidizing bacteria
While most iron is oxidized as a result of interaction with atmospheric oxygen or oxygenated waters, oxidation by bacteria is an active process in anoxic environments and in oxygenated, low pH (<3) environments. Studies of the acidophilic Fe(II)-oxidizing bacterium, Acidthiobacillus ferrooxidans, have been used to determine the fractionation as a result of iron-oxidizing bacteria. In most cases, δ56/54Fe values between 2 and 3‰ were measured. However, a Rayleigh trend with a fractionation factor of αFe(III)aq-Fe(II)aq ~ 1.0022 was observed, which is smaller than the fractionation factor in the abiotic control experiments (αFe(III)aq-Fe(II)aq ~ 1.0034), which has been inferred to reflect a biological isotope effect. Using iron isotopes, an improvement in the understanding of the metabolic processes controlling iron oxidation and energy production in these organisms can be developed.
Photoautrophic bacteria, which oxidize Fe(II) under anaerobic conditions, have also been studied. The Thiodictyon bacteria precipitate poorly crystalline hydrous ferric oxide when they oxidize iron. The precipitate was enriched in the 56Fe relative to Fe(II)aq, with a δ56/54Fe value of +1.5 ± 0.2‰.
Magnetotactic bacteria
Magnetotactic bacteria are bacteria with magnetosomes that contain magnetic crystals, usually magnetite or greigite, which allow them to orient themselves with the Earth’s magnetic field lines. These bacteria mineralize magnetite via the reduction of Fe(III), usually in microaerobic or anoxic environments. In the magnetotactic bacteria that have been studied, there was no significant iron isotope fractionation observed.
Phytoplankton
Iron is important for the growth of phytoplankton. In phytoplankton, iron is used for electron transfer reactions in photosynthesis in both photosystem I and photosystem II. Additionally, iron is an important component of the enzyme nitrogenase, which is used to fix nitrogen. In measurements at open ocean stations, phytoplankton are isotopically light, with the fractionation as a result of biological uptake measured between -0.25‰ and -0.13‰. Improvement in the understanding of this fractionation will enable the more precise understanding of phytoplankton photosynthetic processes.
Animals
Iron has many important roles in animal biology, specifically when considering oxygen transport in the bloodstream, oxygen storage in muscles, and enzymes. Known isotope variations are shown in the figure below. Iron isotopes could be useful tracers of the iron biochemical pathways in animals, and also be indicative of trophic levels in a food chain.
Iron isotope variations in humans reflects a number of processes. Specifically, iron in the blood stream reflects dietary iron, which is isotopically lighter than iron in the geosphere. Iron isotopes are distributed heterogeneously throughout the body, primarily to red blood cells, the liver, muscle, skin, enzymes, nails, and hair. Iron losses in the body (intestinal bleeding, bile, sweat, etc.) favor the loss of isotopically heavy iron, with mean losses averaging a δ56Fe of +10‰. Iron absorption in the intestine favors lighter iron isotopes. This is largely due to the fact that iron is carried by transport proteins and transferrin, both of which are kinetic processes, resulting in the preferential uptake of isotopically light iron.
The observed iron isotopic variations in humans and animals are particularly important as tracers. Iron isotopic signatures are utilized to determine the geographic origin of food. Additionally, anthropologists and paleontologists use iron isotope data in order to track the transfer of iron between the geosphere and the biosphere, specifically between plant foods and animals. This allows for the reconstruction of ancient dietary habits based on the variations in iron isotopes in food.
Geochemistry
By mass, iron is the most common element on Earth, and it is the fourth most abundant element in the Earth's crust. Thus, iron is widespread throughout the geosphere, and is also common on other planetary bodies. Natural variations in the iron in the geosphere are relatively small. Currently, the values of δ56/54Fe measured in rocks and minerals range from -2.5‰ to +1.5‰. Iron isotope composition is homogeneous in igneous rocks to ±0.05‰, indicating that much of the geologic isotopic variability is a result of the formation of rocks and minerals at low temperature. This homogeneity is particularly useful when tracing processes which result in fractionation through the system. While fractionation of igneous rocks is relatively constant, there are larger variations in the iron isotopic composition of chemical sediments. Thus, iron isotopes are used to determine the origin of the protolith of heavily metamorphosed rocks of a sedimentary origin. Improvements of the understanding regarding the way in which iron isotopes fractionate in the geosphere can help to better understand geologic processes of formation.
Natural iron isotopic variations
To date, iron is one of the most widely studied trace metals, and iron isotope compositions are relatively well-documented. Based on measurements, iron isotopes exhibit minimal variation (±3‰) in the terrestrial environment. A list of iron isotopic values of different materials from different environments is presented below.
In terrestrial environments
There is an extreme constancy of the isotopic composition of igneous rocks. The mean value of δ56Fe of terrestrial rocks is 0.00 ± 0.05‰. More precise isotopic measurements indicate that the small deviations from 0.00‰ may reflect a slight mass-dependent fractionation. This mass fractionation has been proposed to be FFe = 0.039 ± 0.008‰ per atomic mass unit relative to IRMM-014. There may also be slight isotopic variations in igneous rocks depending on their composition and process of formation. The average value of δ56Fe for ultramafic igneous rocks is -0.06‰, whereas the average value of δ56Fe for mid-ocean ridge basalts (MORB) is +0.03‰. Sedimentary rocks exhibit slightly larger variations in δ56Fe, with values between -1.6‰ and +0.9‰ relative to IRMM-014. Banded iron formations δ56Fe span the entire range observed on Earth, from -2.5‰ to +1‰.
In the oceans
There are slight iron isotopic variations in the oceans relative to IRMM-014, which likely reflect variations in the biogeochemical cycling of iron within a given ocean basin. In the southeastern Atlantic, δ56Fe values between -0.13 and +0.21‰ have been measured. In the north Atlantic, δ56Fe values between -1.35 and +0.80‰ have been measured. In the equatorial Pacific δ56Fe values between -0.03 and +0.58‰ have been measured. The supply of aerosol iron particles to the ocean have an isotopic composition of approximately 0‰. Dissolved iron riverine input to the ocean is isotopically light relative to igneous rocks, with δ56Fe values between -1 and 0‰.
Most modern marine sediments have δ56Fe values similar to those of igneous δ56Fe values. Marine ferromanganese nodules have δ56Fe values between -0.8 and 0‰.
In hydrothermal systems
Hot (> 300 °C) hydrothermal fluids from mid ocean ridges are isotopically light, with δ56Fe between -0.2 and -0.8‰. Particles in hydrothermal plumes are isotopically heavy relative to the hydrothermal fluids, with δ56Fe between 0.1 and 1.1‰. Hydrothermal deposits have average δ56Fe between -1.6 and 0.3‰. The sulfide minerals within these deposits have δ56Fe between -2.0 and 1.1‰.
In extraterrestrial objects
Variations in iron isotopic composition have been observed in meteorite samples from other planetary bodies. The Moon has variations in iron isotopes of 0.4‰ per atomic mass unit. Mars has very small isotope fractionation of 0.001 ± 0.006‰ per atomic mass unit. Vesta has iron fractionations of 0.010 ± 0.010‰ per atomic mass unit. The chondritic reservoir exhibits fractionations of 0.069 ± 0.010‰ per atomic mass unit. Isotopic variations observed on planetary bodies can help to constrain and better understand their formation and processes occurring in the early Solar System.
Measurement
High precision iron isotope measurements are obtained either via thermal ionization mass spectrometry (TIMS) or multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS).
Applications of iron isotopes
Iron isotopes have many applications in the geosciences, biology, medicine, and other fields. Their ability to act as isotopic tracers allows for their use to determine information regarding the formation of geologic units and as a potential proxy for life on Earth and other planets. Iron isotopes also have applications in anthropology and paleontology, as they are used to study the diets of ancient civilizations and animals. The widespread uses of iron in biology make its isotopes a promising frontier in biomedical research, specifically their use to prevent and treat blood conditions and other pathological blood diseases. Some of the more prevalent applications of iron isotopes are described below.
Banded iron formations
Banded iron formations (BIFs) are particularly important when considering the surface environments of the early Earth, which were significantly different from the surface environments observed today. This is manifested in the mineralogy of these formations, which are indicative of different redox conditions. Additionally, BIFs are interesting in that they were deposited while major changes were occurring in the atmosphere and in the biosphere 2.8 to 1.8 billion years ago. Iron isotopic studies can reveal the details of the formation of BIFs, which allows for the reconstruction of redox and climatic conditions at the time of deposition.
BIFs formed as a result of the oxidation of iron by oxygen, which was likely generated by the evolution of cyanobacteria. This was followed by the subsequent precipitation of iron particles in the ocean. Observed variations in the iron isotopic composition of BIFs span the entire range observed on Earth, with δ56/54Fe values between -2.5 and +1‰. The cause of these variations are hypothesized to occur for three reasons. The first relates to the varying mineralogy of the BIFs. Within the BIFs, minerals such as hematite, magnetite, siderite, and pyrite are observed. These minerals each having varying isotopic fractionation, likely as a result of their structures and the kinetics of their growth. The isotopic composition of the BIFs is indicative of the fluids from which they precipitated, which has applications when reconstructing environmental conditions of the ancient Earth. It has also been suggested that BIFs may be biologic in origin. The range of their δ56/54Fe values fall within the range of those observed to occur as a result of biologic processes relating to bacterial metabolic processes, such as those of anoxygenic phototrophic iron-oxidizing bacteria. Ultimately, the improved understanding of BIFs using iron isotope fractionations would allow for the reconstruction of past environments and the constraint of processes occurring on the ancient Earth. However, given that the values observed as a result of biogenic and abiogenic fractionation are relatively similar, the exact processes of BIFs are still unclear. Thus, the continued study and improved understanding of biologic and abiologic fractionation effects would be beneficial in providing better details regarding BIF formation.
Iron cycling in the ocean
Iron isotopes have become particularly useful in recent years for tracing biogeochemical cycling in the oceans. Iron is an important micronutrient for living species in the ocean, particularly for the growth of phytoplankton. Iron is estimated to limit phytoplankton growth in about one half of the ocean. As a result, the development of a better understanding of sources and cycling of iron in the modern oceans is important. Iron isotopes have been used to better constrain these pathways through data collected by the GEOTRACES program, which has collected iron isotopic data throughout the ocean. Based on the variations in iron isotopes, biogeochemical cycling and other processes controlling iron distribution in the ocean can be elucidated.
For example, the combination of iron concentration and iron isotope data can use to determine the sources of oceanic iron. In the South Atlantic and in the Southern Ocean, isotopically light iron is observed in intermediate waters (200 - 1,300 meters), whereas isotopically heavy iron is observed in surface waters and deep waters (> 1,300 meters). To first order, this demonstrates that there are different sources, sinks, and processes contributing to the iron cycle in varying water masses. The isotopically light iron in intermediate waters suggests that the dominant iron sources include remineralized organic matter. This organic matter is isotopically light because phytoplankton preferentially take up light iron. In the surface ocean, the isotopically heavy iron represents the external sources of iron, such as dust, which is isotopically heavy relative to IRMM-014, and the sink of light isotopes as a result of their preferential uptake by phytoplankton. The isotopically heavy iron in the deep ocean suggests that the iron cycle is dominated by the abiotic, non-reductive release of iron, via desorption or dissolution, from particles. Isotopic analyses similar to the one above are utilized throughout all of the world's oceans to better understand regional variability in the processes which control iron cycling. These analyses can then be synthesized to better model the global biogeochemical cycling of iron, which is particularly important when considering primary production in the ocean.
Constraining processes on extraterrestrial bodies
Iron isotopes have been applied for a number of purposes on planetary bodies. Their variations have been measured to more precisely determine the processes that occurred during planetary accretion. In the future, the comparison of observed biological fractionation of iron on Earth to fractionation on other planetary bodies may have astrobiological implications.
Planetary accretion
One of the primary challenges in the study of planetary accretion is the fact that many tracers of the processes occurring in the early Solar System have been eliminated as a result of subsequent geologic events. Because transition metals do not show large stable isotope fractionations as a result of these events and because iron is one of the most abundant elements in the terrestrial planets, its isotopic variability has been used as a tracer of early Solar System processes.
Variations in δ57/54Fe between samples from Vesta, Mars, the Moon, and Earth have been observed, and these variations cannot be explained by any known petrological, geochemical, or planetary processes, thus, it has been inferred that the observed fractionations are a result of planetary accretion. It is interesting to note that the isotopic compositions of the Earth and the Moon are much heavier than that of Vesta and Mars. This provides strong support for the giant-impact hypothesis as an impact of this energy would generate large amounts of energy, which would melt and vaporize iron, leading to the preferential escape of the lighter iron isotopes to space. More of the heavier isotopes would remain, resulting in the heavier iron isotopic compositions observed for the Earth and the Moon. The samples from Vesta and Mars exhibit minimal fractionation, consistent with the theory of runaway growth for their formations, as this process would not yield significant fractionations. Further study of the stable isotope of iron in other planetary bodies and samples could provide further evidence and more precise constraints for planetary accretion and other processes that occurred in the early Solar System.
Astrobiology
The use of iron isotopes may also have applications when studying potential evidence for life on other planets. The ability of microbes to utilize iron in their metabolisms makes it possible for organisms to survive in anoxic, iron-rich environments, such as Mars. Thus, the continual improvement of knowledge regarding the biological fractionations of iron observed on Earth can have applications when studying extraterrestrial samples in the future. While this field of research is still developing, this could provide evidence regarding whether a sample was generated as a result of biologic or abiologic processes depending on the isotopic fractionation. For example, it has been hypothesized that magnetite crystals found in Martian meteorites may have formed biologically as a result of their striking similarity to magnetite crystals produced by magnetotactic bacteria on Earth. Iron isotopes could be used to study the origin of the proposed "magnetofossils" and other rock formations on Mars.
Biomedical research
Iron plays many roles in human biology, specifically in oxygen transport, short-term oxygen storage, and metabolism Iron also plays a role in the body's immune system. Current biomedical research aims to use iron isotopes to better understand the speciation of iron in the body, with hopes of eventually being able to reduce the availability of free iron, as this would help to defend against infection.
Iron isotopes can also be utilized to better understand iron absorption in humans. The iron isotopic composition of blood reflects an individual's long-term absorption of dietary iron. This allows for the study of genetic predisposition to blood conditions, such as anemia, which will ultimately enable the prevention, identification, and resolution of blood disorders. Iron isotopic data could also aid in identifying impairments of the iron absorption regulatory system in the body, which would help to prevent the development of pathological conditions related to issues with iron regulation.
Cobalt
Nickel
Copper
Stable isotopes and natural abundances
Copper has two naturally occurring stable isotopes: 63Cu and 65Cu, which exist in the following natural abundances:
The isotopic composition of Cu is conventionally reported in delta notation (in ‰) relative to a NIST SRM 976 standard:
Chemistry
Copper can exist in non-ionic form (as Cu0) or in one of two redox states: Cu1+ (reduced) or Cu2+ (oxidized). Each form of Cu has a specific distribution of electrons (i.e., electron configuration), tabulated below:
The electronic configurations of Cu control the number and types of bonds Cu can form with other atoms (e.g., see Copper Biology section). These diverse coordination chemistries are what enable Cu to participate in many different biological and chemical reactions.
Finally, due to its full d-orbital, Cu1+ has diamagnetic resonance. In contrast, Cu2+ has one unpaired electron in its d-orbital, giving it paramagnetic resonance. The different resonances of the Cu ions enable determination of Cu's redox state by techniques such as electron paramagnetic resonance (epr) spectroscopy, which can identify atoms with unpaired electrons by exciting electron spins.
Equilibrium isotope fractionation
Transitions between redox species Cu1+ and Cu2+ fractionate Cu isotopes. 63Cu2+ is preferentially reduced over 65Cu2+, leaving the residual Cu2+ enriched in 65Cu. The equilibrium fractionation factor for speciation between Cu2+ and Cu1+ (αCu(II)-Cu(I)) is 1.00403 (i.e., dissolved Cu2+ is enriched in 65Cu by ~+4‰ relative to Cu1+).
Biology
Copper can be found in the active sites of most enzymes that catalyze redox reactions (i.e., oxidoreductases), as it facilitates single electron transfers while reversibly oscillating between the Cu1+ and Cu2+ redox states. Enzymes typically contain between one (mononuclear) and four (tetranuclear) copper centers, which enable enzymes to catalyze different reactions. These copper centers coordinate with different ligands depending on the Cu redox state. Oxidized Cu2+ preferentially coordinates with "hard donor" ligands (e.g., N- or O-containing ligands such as histidine, aspartic acid, glutamic acid or tyrosine), while reduced Cu1+ preferentially coordinates with "soft donor" ligands (e.g., S-containing ligands such as cysteine or methionine). Copper's powerful redox capability makes it critically important for biology, but comes at a cost: Cu1+ is a highly toxic metal to cells because it readily abstracts single electrons from organic compounds and cellular material, leading to production of free radicals. Thus, cells have evolved specific strategies for carefully controlling the activity of Cu1+ while exploiting its redox behavior.
Examples of copper-based enzymes
Copper serves catalytic and structural roles in many essential enzymes in biology. In the context of catalytic activity, copper proteins function as electron or oxygen carriers, oxidases, mono- and dioxygenases and nitrite reductases. In particular, copper-containing enzymes include hemocyanins, one flavor of superoxide dismutase (SOD), metallothionein, cytochrome c oxidase, multicopper oxidase and particulate methane monooxygenase (pMMO).
Biological fractionation
Biological processes that fractionate Cu isotopes are not well-understood, but play an important role in driving the δ65Cu values of materials observed in the marine and terrestrial environments. The natural 65Cu/63Cu varies according to copper's redox form and the ligand to which copper binds. Oxidized Cu2+ preferentially coordinates with hard donor ligands (e.g., N- or O-containing ligands), while reduced Cu1+ preferentially coordinates with soft donor ligands (e.g., S-containing ligands). As 65Cu is preferentially oxidized over 63Cu, these isotopes tend to coordinate with hard and soft donor ligands, respectively. Cu isotopes can fractionate upon Cu-bacteria interactions from processes that include Cu adsorption to cells, intracellular uptake, metabolic regulation and redox speciation. Fractionation of Cu isotopes upon adsorption to cellular walls appears to depend on the surface functional groups that Cu complexes with, and can span positive and negative values. Furthermore, bacteria preferentially incorporate the lighter Cu isotope intracellularly and into proteins. For example, E. coli, B. subtilis and a natural consortia of microbes sequestered Cu with apparent fractionations (ε65Cu) ranging from ~-1.0 to -4.4‰. Additionally, fractionation of Cu upon incorporation into the apoprotein of azurin was ~-1‰ in P. aeruginosa, and -1.5‰ in E. coli, while ε65Cu values of Cu incorporation into Cu-metallothionein and Cu-Zn-SOD in yeast were -1.7 and -1.2‰, respectively.
Geochemistry
The concentration of Cu in bulk silicate Earth is ~30 ppm, slightly less than its average concentration (~72 ppm) in fresh mid-oceanic ridge basalt (MORB) glass. and form a variety of sulfides (often in association with Fe), as well as carbonates and hydroxides (e.g., chalcopyrite, chalcocite, cuprite and malachite). In mafic and ultramafic rocks, Cu tends to be concentrated in sulfidic materials. In freshwater, the predominant form of Cu is free Cu2+; in seawater, Cu complexes with carbonate ligands to form and .
Measurement
In order to measure Cu isotope ratios of various materials, several steps must be taken prior to the isotopic measurement in order to extract and purify copper. The first step in the analytical pipeline to measure Cu isotopes is to liberate Cu from its host material. Liberation should be quantitative, otherwise fractionation may be introduced at this step. Cu-containing rocks are generally dissolved with HF; biological materials are commonly digested with HNO3. Seawater samples must be concentrated due to the low (nM) concentrations of Cu in the ocean. The sample material is subsequently run through an anion-exchange column to isolated and purify Cu. This step can also introduce Cu isotope fractionation if Cu is not quantitatively recovered from the column. If samples are from seawater, other ions (e.g., Na+, Mg2+, Ca2+) must be removed in order to eliminate isobaric interferences during the isotope measurement. Prior to 1992, 65Cu/63Cu ratios were measured via thermal ionization mass spectrometry (TIMS). Today, Cu isotopic compositions are measured via multi-conductor inductively coupled plasma mass spectrometry (MC-ICP-MS), which ionizes samples using inductively coupled plasma and introduces smaller errors than TIMS.
Natural copper isotopic variations
The field of Cu isotope biogeochemistry is still in a relatively early stage, so the Cu isotope compositions of materials in the environment are not well-documented. However, based on a compilation of measurements already made, it appears that Cu isotope ratios vary somewhat widely within and between environmental materials (e.g., plants, minerals, seawater, etc.), though as a whole, these ratios do not vary by more than ±10‰.
In humans
In human bodies, coppers is an important constituent of many essential enzymes, including ceruloplasmin (which carries Cu and oxidizes Fe2+ in human plasma), cytochrome c oxidase, metallothionein and superoxide dismutase 1. Serum in human blood is typically 65Cu-depleted by ~0.8‰ relative to erythrocytes (i.e., red blood cells). In a study of 49 male and female blood donors, the average δ65Cu value of the donors' blood serum was -0.26 ± 0.40‰, while that of their erythrocytes was +0.56 ± 0.50‰. In a separate study, δ65Cu values of serum in 20 healthy patients ranged from -0.39 to +0.38‰, while the δ65Cu values of their erythrocytes ranged from +0.57 to +1.24‰. To balance Cu loss due to menstruation, a large portion of Cu in the blood of menstruating women comes from their liver. Due to fractionation associated with Cu transport from the liver to the blood, the total blood of pre-menopausal women is generally 65Cu-depleted relative to that of males and non-menstruating women. The δ65Cu values of healthy human liver tissue in 7 patients ranged from -0.45 to -0.11‰.
In the terrestrial environment
To first order, δ65Cu values in organisms are driven by the δ65Cu values of source materials. The δ65Cu values of various soils from different regions have been found to vary from -0.34 to +0.33‰ depending on the biogeochemical processes taking place in the soil and the ligands with which Cu complexes. Organic-rich soils generally have lighter δ65Cu values than mineral soils because the organic layers result from plant litter, which is isotopically light.
In plants, δ65Cu values vary between the different components (seeds, roots, stem and leaves). The δ65Cu values the roots of rice, lettuce, tomato and durum wheat plants were found to be 0.5 to 1.0‰ 65Cu-depleted relative to their source, while their shoots were up to 0.5‰ lighter than the roots. Seeds appear to be the most isotopically light component of plants, followed by leaves, then stems.
Rivers sampled throughout the world have a range of dissolved δ65Cu values from +0.02 to +1.45‰. The average δ65Cu values of the Amazon, Brahmaputra and Nile rivers are 0.69, 0.64 and 0.58‰, respectively. The average δ65Cu value of the Chang Jiang river is 1.32‰, while that of the Missouri river is 0.13‰.
In rocks and minerals
In general, igneous, metamorphic and sedimentary processes do not appear to strongly fractionate Cu isotopes, while δ65Cu values of Cu minerals vary widely. The average Cu isotopic composition of bulk silicate Earth has been measured as 0.06 ± 0.20‰ based on 132 different terrestrial samples. MORBs and oceanic island basalts (OIBs) generally have homogenous Cu isotopic compositions that fall around 0‰, while arc and continental basalts have more heterogeneous Cu isotope compositions that range from -0.19 to +0.47‰. These Cu isotope ratios of basalts suggest that mantle partial melting imparts negligible Cu isotopic fractionation, while recycling of crustal materials leads to widely variable δ65Cu values. The Cu isotope compositions of copper-containing minerals vary over a wide range, likely due to alteration of the primary high-temperature deposits. In one study that investigated Cu isotopic compositions of various minerals from hydrothermal fields along the mid-Atlantic ridge, chalcopyrite from mafic igneous rocks had δ65Cu values of -0.1 to -0.2‰, while Cu minerals in black smokers (chalcopyrite, bornite, covellite and atacamite) exhibited a wider range of δ65Cu values from -1.0 to +4.0‰. Additionally, atacamite lining the outer rims of black smokers can be up to 2.5‰ heavier than chalcopyrite contained within the black smoker. δ65Cu values of Cu minerals (including chrysocolle, azurite, malachite, cuprite and native copper) in low-temperature deposits have been observed to vary widely over a range of -3.0 to +5.6‰.
In the marine environment
Cu is strongly cycled in the surface and deep ocean. In the deep ocean, Cu concentrations are ~5 nM in the Pacific and ~1.5 nM in the Atlantic. The deep/surface ratio of Cu in the ocean is typically <10, and vertical concentration profiles for Cu are roughly linear due to biological recycling and scavenging processes as well as adsorption to particles.
Due to equilibrium and biological processes that fractionate Cu isotopes in the marine environment, the bulk copper isotopic composition (δ65Cu = +0.6 to +1.5‰) is different from the δ65Cu values of the riverine input (δ65Cu = +0.02 to +1.45‰, with discharge-weighted average δ65Cu = +0.68‰) to the oceans. δ65Cu values of the surface layers of FeMn-nodules are fairly homogenous throughout the oceans (average = 0.31‰), suggesting low biological demand for Cu in the marine environment compared to that of Fe or Zn. Additionally, δ65Cu values in the Atlantic ocean do not markedly vary with depth, ranging from +0.56 to +0.72‰. However, Cu isotope compositions of material collected on sediment traps at depths of 1,000 and 2,500 m in the central Atlantic ocean show seasonal variation with heaviest δ65Cu values in the spring and summer seasons suggesting seasonal preferential uptake of 63Cu by biological processes.
Equilibrium processes that fractionate Cu isotopes include high temperature ion exchange and redox speciation between mineral phases, and low temperature ion exchange between aqueous species or redox speciation between inorganic species. In riverine and marine environments, 65Cu/63Cu ratios are driven by preferential adsorption of 63Cu to particulate matter and preferential binding of 65Cu to organic complexes. As a net result, ocean sediments tend to be depleted in 63Cu relative to the bulk ocean. For example, the downcore δ65Cu values of a 760 cm sedimentary core taken from the Central Pacific ocean varied from -0.94 to -2.83‰, significantly lighter than the bulk ocean.
Applications of copper isotopes
Medicine
Due to its relatively short turnover time of ~6 weeks in the human body, Cu serves as an important indicator of cancer and other diseases that rapidly evolve. The serum of cancer patients contains significantly higher levels of Cu than that of healthy patients due to copper chelation by lactate, which is produced via anaerobic glycolysis by tumor cells. These imbalances in Cu homeostasis are reflected isotopically in the serum and organ tissues of patients with various types of cancer, where the serum of cancer patients is generally 65Cu-depleted relative to the serum of healthy patients, while organ tumors are generally 65Cu-enriched. In one study, the blood components of patients with hepatocellular carcinomas (HCC) was found to be, on average, depleted in 65Cu by 0.4‰ relative to the blood of non-cancer patients. In particular, the δ65Cu values of the serum in patients with HCC ranged from -0.66 to +0.47‰ (compared to serum δ65Cu values of -0.39 to +0.38‰ in matched control patients), and the δ65Cu values of the erythrocytes in the HCC patients ranged from -0.07 to +0.92‰ (compared to erythrocyte δ65Cu values of +0.57 to +1.24‰ in matched control patients). The liver tumor tissues in the HCC patients were 65Cu-enriched relative to healthy liver tissue in the same patients (δ65Culiver, HCC = -0.02 to +0.43‰; δ65Culiver, healthy = -0.45 to -0.11‰), and the magnitude of 65Cu-enrichment mirrored that of the 65Cu-depletion observed in the cancer patients' serum. Though our understanding of how copper isotopes are fractionated during cancer physiologies is still limited, it is clear that copper isotope ratios may serve as a powerful biomarker of cancer presence and progression.
Zinc
Stable isotopes and natural abundances
Zinc has five stable isotopes, tabulated along with their natural abundances below:
The isotopic composition of Zn is reported in delta notation (in ‰):
where xZn is a Zn isotope other than 64Zn (commonly either 66Zn or 68Zn). Standard reference materials used for Zn isotope measurements are JMC 3-0749C, NIST-SRM 683 or NIST-SRM 682.
Chemistry
Because it has just one valence state (Zn2+), zinc is a redox-inert element. The electronic configurations of Zn0 and Zn2+ are shown below:
Biology
Zinc is present in almost 3,000 human proteins, and thus is essential for nearly all cellular functions. Zn is also a key constituent of enzymes involved in cell regulation. Consistent with its ubiquitous presence, total cellular Zn concentrations are typically very high (~200 μM), while the concentrations of free Zn ions in the cytoplasms of cells can be as low as a few hundred picomolar, maintained within a narrow range to avoid deficiency and toxicity. One feature of Zn that makes it so critical in cellular biology is its flexibility in coordination to different numbers and types of ligands. Zn can coordinate with anywhere between three and six N-, O- and S-containing ligands (such as histidine, glutamic acid, aspartic acid and cysteine), resulting in a large number of possible coordination chemistries. Zn tends to bind to metal sites of proteins with relatively high affinities compared to other metal ions which, aside from its important functions in enzymatic reactions, partly explains its ubiquitous presence in cellular enzymes.
Examples of zinc-based enzymes
Zn is present in the active sites of most hydrolytic enzymes, and is used as an electrophilic catalyst to activate water molecules that ultimately hydrolyze chemical bonds. Examples of zinc-based enzymes include superoxide dismutase (SOD), metallothionein, carbonic anhydrase, Zn finger proteins, alcohol dehydrogenase and carboxypeptidase.
Biological fractionation
Relatively little is known about isotopic fractionation of zinc by biological processes, but several studies have elucidated that Zn isotopes fractionate during surface adsorption, intracellular uptake processes and speciation. Many organisms, including certain species of fish, plants and marine phytoplankton, have both high- and low-affinity Zn transport systems, which appear to fractionate Zn isotopes differently. A study by John et al. observed apparent isotope effects associated with Zn uptake by the marine diatom Thalassiosira oceanica of -0.2‰ for high-affinity uptake (at low Zn concentrations) and -0.8‰ for low-affinity uptake (at high Zn concentrations). Additionally, in this study, unwashed cells were enriched in 65Zn, indicating preferential adsorption of 65Zn to the extracellular surfaces of T. oceanica. Results from John et al. demonstrating apparent discrimination against the heavy isotope (66Zn) during uptake conflict with results by Gélabert et al. in which marine phytoplankton and freshwater periphytic organisms preferentially uptook 66Zn from solution. The latter authors explained these results as due to a preferential partitioning of 66Zn into a tetrahedrally coordinated structure (i.e., with carboxylate, amine or silanol groups on or inside the cell) over an octahedral coordination with six water molecules in the aqueous phase, consistent with quantum mechanical predictions. Kafantaris and Borrok grew model organisms B. subtilis, P. mendocina and E. coli, as well as a natural bacterial consortium collected from soil, on high and low concentrations of Zn. In the high [Zn] condition, the average fractionation of Zn isotopes imparted by cellular surface adsorption was +0.46‰ (i.e., 66Zn was preferentially adsorbed), while fractionation upon intracellular incorporation varied from -0.2 to +0.5‰ depending on the bacterial species and growth phase. Empirical models of the low [Zn] condition estimated larger Zn isotope fractionation factors for surface adsorption ranging from +2 to +3‰. Overall, Zn isotope ratios in microbes appear to be driven by a number of complex factors including surface interactions, bacterial metal metabolism and metal speciation, but by understanding the relative contributions of these factors to Zn isotope signals, one can use Zn isotopes to investigate metal-binding pathways operating in natural communities of microbes.
Geochemistry
The concentration of Zn in bulk silicate Earth is ~55 ppm, while its average concentration in fresh mid-oceanic ridge basalt (MORB) glass is ~87 ppm. Like Cu, Zn commonly associates with Fe to form a variety of zinc sulfide minerals such as sphalerite. Additionally, Zn associates with carbonates and hydroxides to form numerous diverse minerals (e.g., smithsonite, sweetite, etc.). In mafic and ultramafic rocks, Zn tends to concentrate in oxides such as spinel and magnetite. In freshwater, Zn predominantly complexes with water to form an octahedrally coordinated aqua ion . In seawater, Cl− ions replace up to four water molecules in the Zn aqua ion, forming , and .
Measurement
The analytical pipeline for preparation of sample material for Zn isotope measurements is similar to that of Cu, consisting of digestion of host material or concentration from seawater, isolation and purification via anion-exchange chromatography, removal of ions of interfering mass (in particular, 64Ni) and isotope measurement via MC-ICP-MS (see Copper Isotope Measurement section for more details).
Natural zinc isotopic variations
As with Cu, the field of Zn isotope biogeochemistry is still in a relatively early stage, so the Zn isotope compositions of materials in the environment are not well-documented. However, based on a compilation of some reported measurements, it appears that Zn isotope ratios do not vary widely among environmental materials (e.g., plants, minerals, seawater, etc.), as δ66Zn values of materials typically fall within a range of -1 to +1‰.
In humans
Zn isotope ratios vary between individual blood components, bones and the different organs in humans, though in general, δ66Zn values fall within a narrow range. In the blood of healthy individuals, the Zn isotopic composition of erythrocytes is typically ~0.3‰ lighter than that of serum, and no significant differences in erythrocyte or serum δ66Zn values exist between men and women. For example, in the blood of 49 healthy blood donors, the average erythrocyte δ66Zn value was +0.44 ± 0.33‰, while that of serum was +0.17 ± 0.26‰. In a separate study on 29 donors, a similar average δ66Zn value of +0.29 ± 0.27‰ was obtained for the patients' serum. Additionally, in a small sample set of volunteers, whole blood δ66Zn values were ~+0.15‰ higher for vegetarians than for omnivores, suggesting diet plays an important role in driving Zn isotope compositions in the human body.
In the terrestrial environment
Zn isotope ratios vary on small scales throughout the terrestrial biosphere. Zn is released into soils during mineral weathering, and isotopes of Zn fractionate upon interaction with mineral and organic components in the soil. In 5 soil profiles collected from Iceland (all derived from the same parent basalt), soil δ66Zn values varied from +0.10 to +0.35‰, and the organic-rich layers were 66Zn-depleted relative to the mineral-rich layers, likely due to contribution by isotopically light organic matter and Zn loss by leaching.
Isotopic discrimination of Zn varies in different components of higher plants, likely due to the various processes involved in Zn uptake, binding, transport, diffusion, speciation and compartmentalization. For example, Weiss et al. observed heavier δ66Zn values in the roots of several plants (rice, lettuce and tomato) relative to the bulk solution in which the plants were grown, and the shoots of those plants were 66Zn-depleted relative to both their roots and bulk solution. Furthermore, Zn isotopes partition differently between different Zn-ligand complexes, so the form of Zn incorporated by organisms in the terrestrial biosphere plays a role in driving Zn isotope compositions of the organisms. In particular, based on ab initio calculations, Zn-phosphate complexes are expected to be isotopically heavier than Zn-citrates, Zn-malates and Zn-histidine complexes by 0.6 to 1‰.
The discharge- and [Zn]-weighted average δ66Zn value of rivers throughout the world is +0.33‰. In particular, the average δ66Zn values of the Kalix and Chang Jiang rivers are +0.64 and +0.56‰, respectively. The Amazon, Missouri and Brahmaputra rivers have average δ66Zn values near +0.30‰, and the average δ66Zn value of the Nile river is +0.21‰.
In rocks and minerals
In general, δ66Zn values of various rocks and minerals do not appear to significantly vary. The δ66Zn value of bulk silicate Earth (BSE) is +0.28 + 0.05‰. Fractionation of Zn isotopes by igneous processes is generally insignificant, and δ66Zn values of basalt fall within the range of +0.2 to +0.3‰, encompassing the value for BSE. δ66Zn values of clay minerals from diverse environments and of diverse ages have been found to fall within the same range as basalts, suggesting negligible fractionation between the basaltic precursors and sedimentary materials. Carbonates appear to be more 66Zn-enriched than other sedimentary and igneous rocks. For example, the δ66Zn value of a limestone core taken from the Central Pacific was +0.6‰ at the surface and increased to +1.2‰ with depth The Zn isotopic compositions of various ores are not well-characterized, but smithsonites and sphalerites (Zn carbonates and Zn sulfides, respectively) collected from various localities in Europe had δ66Zn values ranging from -0.06 to +0.69‰, with smithsonite potentially slightly heavier by 0.3‰ than sphalerite.
In the marine environment
Zn is an essential biological nutrient in the oceans, and its concentration is largely controlled by uptake by phytoplankton and remineralization. In addition to its critical role in many metalloenzymes (see Zinc Biology section), Zn is an important component of the carbonate shells of foraminifera and siliceous frustules in diatoms. The main inputs of Zn to the ocean are thought to be from rivers and dust. In some photic zones in the ocean, Zn is a limiting nutrient for phytoplankton, and thus its concentration in surface waters serves as one control on marine primary productivity. Zn concentrations are extremely low in the surface ocean (<0.1 nM) but are maximal at depth (~2 nM in the deep Atlantic; ~10 nM in the deep Pacific), indicating a deep regeneration cycle. The deep/surface ratio of Zn is typically on the order of 100, significantly larger than that observed for Cu.
A multitude of complex processes fractionate Zn isotopes in the marine environment. As seen with copper isotopes, the bulk isotopic composition of zinc in the oceans (δ66Zn = +0.5‰) is heavier than that of the riverine input (δ66Zn = +0.3‰), reflecting both equilibrium, biological and other processes that affect Zn isotope ratios in the ocean. In the surface ocean, phytoplankton preferentially uptake 64Zn, and as a result have average δ66Zn values of ~+0.16‰ (i.e., 0.34‰ lighter than the bulk ocean). This preferential removal of 64Zn by photosynthetic marine organisms in the photic zone is most prominent in the spring and summer seasons when primary productivity is highest, and the seasonal variability of Zn isotope ratios is reflected in the δ66Zn values of settling materials, which are heavier (e.g., by ~+0.20‰ in the Atlantic Ocean) during spring and summer than during the colder seasons. Additionally, the surface layers of FeMn-nodules are 66Zn enriched at high-latitudes (average δ66Zn = +1‰), while δ66Zn values of low-latitude samples are smaller and more variable (spanning +0.5 to +1‰). This observation has been interpreted as due to high levels of Zn consumption and preferential uptake of 64Zn above the seasonal thermocline at high latitudes during warmer seasons, and transfer of this heavy δ66Zn signal to the settling sedimentary Fe-Mn hydroxides.
Sources and sinks for Zn isotopes are further highlighted in the vertical profile of 66Zn/64Zn in the water column. In the upper 2,000 m of the Atlantic Ocean, δ66Zn values are highly variable near the surface (δ66Zn = +0.05 to +0.33‰) due to biological uptake and other surface processes, then gradually increase to ~+0.50‰ at 2,000 m depth. Potential sinks for light Zn isotopes, which enrich the residual bulk Zn isotope ratios in the ocean, include binding to and burial with sinking particulate matter, as well as Zn sulfide precipitation in buried sediments. As a result of preferential burial of 64Zn over the heavier Zn isotopes, sediments in the ocean are generally isotopically lighter than that of bulk seawater. For example, δ66Zn values in 8 sedimentary cores from three different continental margins were depleted in 66Zn relative to the bulk ocean (δ66Zncores = -0.15 to +0.2‰), and furthermore the vertical profiles of δ66Zn values in the cores showed no downcore isotopic variability, suggesting diagenesis does not significantly fractionate Zn isotopes.
Applications of zinc isotopes
Medicine
Zn isotopes may be useful as a tracer for breast cancer. Relative to non-cancerous patients, breast cancer patients are known to have significantly higher concentrations of Zn in their breast tissue, but lower concentrations in their blood serum and erythrocytes, due to overexpression of Zn transporters in breast cancer cells. Consistent with these body-wide shifts in Zn homeostasis, δ66Zn values in breast cancer tumors of 5 patients were found to be anomalously light (varying from -0.9 to -0.6‰) relative to healthy tissue in 3 breast cancer patients and 1 healthy control (δ66Zn = -0.5 to -0.3‰). In this study, δ66Zn values of blood and serum were not found to be significantly different between cancerous and non-cancerous patients, suggesting an unknown isotopically heavy pool of Zn must exist in cancer patients. Though results from this study are promising regarding the use of Zn isotope ratios as a biomarker for breast cancer, a mechanistic understanding of how Zn isotopes fractionate during tumor formation in breast cancer is still lacking. Fortunately, increasing attention is being devoted to the use of stable metal isotopes as tracers of cancer and other diseases, and the usefulness of these isotope systems in medical applications will become more apparent in the next few decades.
Molybdenum
Uranium
References
Biogeochemistry | Trace metal stable isotope biogeochemistry | [
"Chemistry",
"Environmental_science"
] | 13,355 | [
"Environmental isotopes",
"Environmental chemistry",
"Isotopes",
"Chemical oceanography",
"Biogeochemistry"
] |
63,576,976 | https://en.wikipedia.org/wiki/Introduction%20to%20Circle%20Packing | Introduction to Circle Packing: The Theory of Discrete Analytic Functions is a mathematical monograph concerning systems of tangent circles and the circle packing theorem. It was written by Kenneth Stephenson and published in 2005 by the Cambridge University Press.
Topics
Circle packings, as studied in this book, are systems of circles that touch at tangent points but do not overlap, according to a combinatorial pattern of adjacencies specifying which pairs of circles should touch. The circle packing theorem states that a circle packing exists if and only if the pattern of adjacencies forms a planar graph; it was originally proved by Paul Koebe in the 1930s, and popularized by William Thurston, who rediscovered it in the 1970s and connected it with the theory of conformal maps and conformal geometry. As a topic, this should be distinguished from sphere packing, which considers higher dimensions (here, everything is two dimensional) and is more focused on packing density than on combinatorial patterns of tangency.
The book is divided into four parts, in progressive levels of difficulty. The first part introduces the subject visually, encouraging the reader to think about packings not just as static objects but as dynamic systems of circles that change in predictable ways when the conditions under which they are formed (their patterns of adjacency) change. The second part concerns the proof of the circle packing theorem itself, and of the associated rigidity theorem: every maximal planar graph can be associated with a circle packing that is unique up to Möbius transformations of the plane. More generally the same result holds for any triangulated manifold, with a circle packing on a topologically equivalent Riemann surface that is unique up to conformal equivalence.
The third part of the book concerns the degrees of freedom that arise when the pattern of adjacencies is not fully triangulated (it is a planar graph, but not a maximal planar graph). In this case, different extensions of this pattern to larger maximal planar graphs will lead to different packings, which can be mapped to each other by corresponding circles. The book explores the connection between these mappings, which it calls discrete analytic functions, and the analytic functions of classical mathematical analysis. The final part of the book concerns a conjecture of William Thurston, proved by Burton Rodin and Dennis Sullivan, that makes this analogy concrete: conformal mappings from any topological disk to a circle can be approximated by filling the disk by a hexagonal packing of unit circles, finding a circle packing that adds to that pattern of adjacencies a single outer circle, and constructing the resulting discrete analytic function. This part also includes applications to number theory and the visualization of brain structure.
Stephenson has implemented algorithms for circle packing and used them to construct the many illustrations of the book, giving to much of this work the flavor of experimental mathematics, although it is also mathematically rigorous. Unsolved problems are listed throughout the book, which also includes nine appendices on related topics such as the ring lemma and Doyle spirals.
Audience and reception
The book presents research-level mathematics, and is aimed at professional mathematicians interested in this and related topics. Reviewer Frédéric Mathéus describes the level of the material in the book as "both mathematically rigorous and accessible to the novice mathematician", presented in an approachable style that conveys the author's love of the material. However, although the preface to the book states that no background knowledge is necessary, and that the book can be read by non-mathematicians or used as an undergraduate textbook, reviewer Michele Intermont disagrees, noting that it has no exercises for students and writing that "non-mathematicians will be nothing other than frustrated with this book". Similarly, reviewer David Mumford finds the first seven chapters (part I and much of part II) to be at an undergraduate level, but writes that "as a whole, the book is suitable for graduate students in math".
Publication
References
External links
Ken Stephenson's CirclePack software
Circle packing
Mathematics books
2005 non-fiction books | Introduction to Circle Packing | [
"Mathematics"
] | 821 | [
"Circle packing",
"Mathematical problems",
"Packing problems",
"Geometry problems"
] |
63,577,059 | https://en.wikipedia.org/wiki/THC%20production%20by%20yeast | Cannabinoids, including tetrahydrocannabinol (THC), the active drug in cannabis, can also be produced by bioengineered yeast, a process colloquially known as pharming. In 2007, a research group reported the successful transgenic placement of a THCA synthase gene from Cannabis plant into the Pichia pastoris yeast, giving the yeast the ability to turn the precursor molecule cannabigerolic acid into THCA. In 2019, researchers at University of California, Berkeley reported in Nature that they had bioengineered yeast able to completely synthesize THC, CBD, and other cannabinoids, using only sugar as a food.
At least two companies have pursued intellectual property protection for biosynthesis of cannabinoids in yeast. The U.S. National Center for Complementary and Integrative Health has funded research into "techniques to synthesize cannabinoids in yeast", saying that if successful, it "would cost less than obtaining them from the cannabis plant".
See also
Conversion of CBD to THC
List of psychoactive substances and precursor chemicals derived from genetically modified organisms
Hops and cannabinoids
References
Sources
Further reading
2007 in cannabis
2019 in cannabis
American inventions
Genetically modified organisms | THC production by yeast | [
"Engineering",
"Biology"
] | 261 | [
"Genetic engineering",
"Genetically modified organisms"
] |
63,577,372 | https://en.wikipedia.org/wiki/AS%20Labruna | AS Labruna is an Italian marine engine manufacturer and dealer of engines for road transport and aircraft based in Monopoli (Apulia).
Company
AS Labruna is a company founded in 1971 and produces and markets marine diesel engines, marine generators, marine propulsion systems and marine cranes.
Marine is the unit that manufactures and markets marine diesel engines, marine generators, marine propulsion systems and marine cranes; Power is the section dedicated to the design and marketing of industrial diesel engines, vehicles and generators; The Loading sector deals with the marketing and installation of cranes, truck loaders and aerial platforms. In addition to its product line, AS Labruna is an official distributor for other companies.
Distribution
AS Labruna is an official distributor for the following companies:
FPT (FIAT Powertrain Technologies formerly IVECO Aifo) for diesel engines and generators
Ing. Bonfiglioli for cranes
FNM Marine Diesel Engine
VM Motori
See also
FNM Marine
Inboard motor
Labruna
References
Propulsion
Marine engineering
Italian brands
Companies based in Apulia
Engine manufacturers of Italy | AS Labruna | [
"Engineering"
] | 212 | [
"Marine engineering"
] |
78,038,648 | https://en.wikipedia.org/wiki/N-terminal%20acetylation | N-terminal acetylation is the protein modification that occurs on the α-amino acid group at the N-termini of proteins. The backbone amino group on the first amino acid (α-amino group) on a protein N-terminus gets an acetyl group (-COCH3) via acetyl-CoA, and this process is catalyzed by enzymes called N-terminal acetyltransferases (NATs). This changes the chemical properties by making the protein more hydrophobic. Adding an acetyl group on the N-terminus of proteins is to date not shown to be reversible.
Background
Acetylation of a protein is adding an acetyl group on one or several amino acids in the protein. This protein modification can happen internally on an ε- amino acid group of a protein. An internal acetylation is called lysine acetylation, as it is an internal lysine (K) that is added an acetyl group (-COCH3). This process is catalyzed by enzymes named lysine acetyltransferases (KATs) by using acetyl-CoA as donor. This process can be reversed, meaning that the acetyl group can be removed by lysine deacetylases (KDACs).
N-terminal acetyltransferases
There are seven human N-terminal acetyltransferases discovered to date, named NatA, NatB, NatC, NatD, NatE, NatF, and NatH. There is a group of plant NATs discovered called NatG.
NatA, NatB, NatC, NatD and NatE work co-translationally by binding to the ribosome. NatD/NAA40 is in itself ribosome-binding, whereas the remaining four of these NATs bind to the ribosome via an auxiliary subunit. NatF and NatH modify proteins post-translationally and are as far as we know monomeric enzymes. NatA targets about 38% of the human proteome, NatB almost 21%, whereas NatC, NatE and NatF together target in total 21% of the human proteome. That means that the different NATs in total acetylate over 80% of the human proteome, making N-terminal acetylation a highly abundant protein modification.
NatA was the first NAT to be described, and its structure consists of the catalytic subunit NAA10 and the auxiliary subunit NAA15 which together is called the NatA complex. The NatA complex also binds to HYPK (Huntingtin-interacting protein K) which can stabilize the NatA complex. NatA targets proteins starting with S, A, T, G, V and C, and has the largest substrate pool of all the NATs. However, NAA10 can also work independently of NAA15, and acetylate proteins on its own. NatB consists of the catalytic subunit NAA20 and the auxiliary subunit NAA25. The target proteins of NatB are those that have N-termini starting with the amino acids MD, ME, MN and MQ. NatC consists of the catalytic subunit NAA30, and NAA35 which anchors the ribosome and NAA38 whose role is still not known. The targets of NatC are MI-, ML-, MF-, MY- and MK-starting protein N-termini.
NatD consists of one catalytic unit called NAA40 with high substrate selectivity, targeting only histones H2A and H4 and some proteins starting with SGRGK. NatE consists of the unit NAA50 which binds to the NatA complex and HYPK, and this NatE complex targets MS-, MT-, MA-, MV-, ML-, MI-, MF-, MY- and MK-starting N-termini. NatF consists of the catalytic NAA60 and is localized to the cytosolic side of the Golgi membrane, and it is the only known NAT that is specifically targeting membrane proteins. The targets of NatF are MI-, ML-, MF-, MY- and MK-starting membrane proteins. NatH consist of the catalytic NAA80. It is highly specific and targets only actins, including cytoplasmic β-actin and γ-actin. NatH works post-translationally in the cytosol on actin at the final maturation stage of actin and it interacts with profilin which promotes actin N-terminal acetylation
NatG is a group of plant NATs that was discovered in 2015. NatG consists of several plant-specific GNAT proteins with dual functions as KATs and NATs targets chloroplast proteins with N-termini starting with A, M, T, S.
Impact on proteins in human cells and for pathologies
Most proteins in the human body have this protein modification, and there are several cellular and biological functions of N-terminal acetylation. As a general overview, the N-terminal acetylation functions like a label, and the target could be to relocate a protein to a different subcellular location, activate a protein for its proper function. An example is that N-terminally acetylated actin is part of keeping a normal functional cytoskeleton. A modified protein could target the protein for degradation, and for some proteins it can do the opposite and protect it from degradation. An important role of NatC is to protect proteins from degradation otherwise mediated by ubiquitin ligases. In human and plant cells, NatA can also protect proteins from degradation by ubiquitin ligases and thereby stabilize these. There are also reports of N-terminal acetylation could have a stabilizing effect depending on the protein in question.
Lack of N-terminal acetylation has been associated with different pathologies in recent years. Pathogenic variants in the coding DNA region of the NATs may result in a NAT with reduced enzymatic activity. There have been found several patient mutations like this where NatA has been affected. The first case of NatA defect in 2011 had severe consequences, involving developmental delay, heart failures, aged appearance and a short life span. Pathogenic variants have also been found in the coding region of NAA20, where the patients have developed various symptoms like speech delay, epilepsy and cognitive impairment due to weakening of the NatB complex formation. Other diseases linked to lack of N-terminal acetylation involve NatF, where lack of NAA60 activity had shown to cause primary familial brain calcifications. N-terminal acetyltransferases have also been linked to cancer progression, including NAA10, NAA20, NAA30, NAA40 and NAA50. Due to the large number of proteins having these modifications, often malfunction in the N-terminal acetyltransferases the human body have so called pleiotropic effects. As there are several diseases linked to lack of N-terminal acetylation, it is important to investigate genetic variants that lead to disease, but also to do research on the basal functions of NATs to reveal new therapeutic angles for these diseases.
References
Organic reactions | N-terminal acetylation | [
"Chemistry"
] | 1,512 | [
"Organic reactions"
] |
78,039,050 | https://en.wikipedia.org/wiki/Landing%20zone%20%28software%29 | A landing zone is an environment that is made available by cloud computing companies. It is the environment in which the actual workloads run in. Landing zones are available for Microsoft Azure, Amazon Web Services and Google Cloud.
Amazon has also provided educational landing zones to universities, so students could practice with the technology.
See also
Infrastructure as code
References
Cloud computing | Landing zone (software) | [
"Engineering"
] | 72 | [
"Software engineering",
"Software engineering stubs"
] |
78,041,612 | https://en.wikipedia.org/wiki/Alternan | Alternan is a branched α-d-glucan produced by microorganisms. This polymer was first discovered in the bacterium Leuconostoc mesenteroides, which has since been genetically engineered to produce alternan. They genetically engineered the genes for alternansucrase, the enzyme that produces alternan, to get a pure sample. This gene of the enzyme alternansucrase had also been genetically engineered into E. coli.
This compound is highly soluble in water and has a low viscosity. These characteristics make it a prime candidate to use in the food and cosmetic industries.
Biosynthesis
Alternan is an exopolysaccharide generated from the glucose monosaccharides of sucrose by the enzyme alternansucrase. The polysaccharide is assembled with α-(1→6) and α-(1→3) glycosidic bonds. Alternansucrase was initially found in Leuconostoc mesenteroides, a bacterial species used in the dairy industry. L. mesenteroides is a gram positive bacterium that performs fermentation. During fermentation the bacterium produces a very high amount of alternan and dextran, requiring a medium containing sucrose, nitrogen, glutamate, thiamine, and valine. The alternan is then extracted from the fermentation product through centrifugation or filtration.
Industrial use
Alternan has numerous industrial uses. One of the valuable uses is in food production as an essential component of the sweetener sucromalt, also known as Xtend, which is commonly used in diabetic foods due to its low glycemic index. Alternan can also be used to add texture to food or cosmetics in place of fat or oil.
Alternan has shown potential as a bulking agent as it has a low viscosity and high solubility. These properties are shared with other commonly used food extenders and binders. Few microorganisms have the ability to break down alternan, it is also able to retain its structure and properties when exposed to heat, making it a strong candidate to improve shelf-life of food products.
Future Applications
Alternan has shown promising applications in stem cell research. When treating mesenchymal stem cells (MSC) with alternan they showed increased proliferation and viability. Alternan stimulated toll-like receptors in the MSC that are important in differentiation of the cell as well as increased migration abilities of the MSC. Alternan could be a beneficial additive to stem cell therapies to improve outcomes.
References
Wikipedia Student Program
Polysaccharides | Alternan | [
"Chemistry"
] | 551 | [
"Carbohydrates",
"Polysaccharides"
] |
78,042,522 | https://en.wikipedia.org/wiki/Formosissimum | The word formosissimum is a specific epithet used in the name of various species. It derives from the superlative form of , which means "beautiful" or "finely formed".
Plants
The following list consists of flowering plant species names that include formosissimum. Species are included based on the Royal Botanic Garden Kew's Plants of the World Online.
Marine animals
The following list consists of marine animal species names that include formosissimum. Species are included based on the World Register of Marine Species.
Other eukaryotes
The following list consists of other species names that include formosissimum.
References
Set index articles on organisms | Formosissimum | [
"Biology"
] | 132 | [
"Set index articles on organisms"
] |
78,042,541 | https://en.wikipedia.org/wiki/Protecting%20Kids%20From%20Social%20Media%20Act | Protecting Kids on Social Media Act or HB 1891 is an American law that was created by William Lamberth of Sumner County, Tennessee and was later enacted by Tennesse's Governor on May 2, 2024. The bill requires social media websites such as X, YouTube, TikTok, Facebook and others to verify the age of users and if those users are under 18, they must have Parental Consent.
Progress
The law passed the Tennessee State Legislature with little opposition: the bill had only two no votes in the House the two no votes were from Aftyn Behn and Vincent B. Dixie and had zero no votes in the Senate.
Bill summary
Every social media company must verify the age of new users after the law takes effect and if the user had created an account before the law took effect, they must verify the age of the person attempting to access the account within 14 days and if the new user or the user who originally owned an account is under 18 years of age they must get parental consent and the third party or social media company must not retain the data from the process from age verification or obtaining parental consent. Parents who are account holders of those under 18 can view the privacy settings, set daily time restrictions, and implement breaks during which the minor cannot access the account. The law is enforced by the Attorney General of Tennessee and takes effect on January 1, 2025.
Lawsuit
On October 3, 2024, the trade association NetChoice filed a lawsuit against Tennessee Attorney General Jonathan Skrmetti in the Middle District Court of Tennessee, claiming that the law violates the First Amendment. The Judge for the case is William L. Campbell Jr. An initial case management conference was originally scheduled for December 4, 2024, however, was delayed because of the Supreme Court case United States v. Skrmetti, recommending that the conference be delayed after January 20, 2025.
As of 7:40 PM Eastern US time on December 31, 2024 (just 4 hours and 20 minutes before the law will take effect in the counties of Tennessee that are in the Eastern Time Zone), this Tennessee social media law does not seem to have been blocked from going into place, despite a similar Tennessee law requiring age verification for pornography having been blocked earlier in the day.
References
Tennessee law
Child welfare in the United States
Internet law in the United States
Social media
2024 in American law
Child online safety laws | Protecting Kids From Social Media Act | [
"Technology"
] | 484 | [
"Computing and society",
"Social media"
] |
78,042,909 | https://en.wikipedia.org/wiki/Treni%20della%20felicit%C3%A0 | The treni della felicità () was a post-war initiative by the Italian Communist Party and the , whereby 70,000 impoverished children from southern Italy were transported to northern Italy between 1945 and 1952 to be hosted by families that could support them.
History
The initiative was conceived by Teresa Noce and the (UDI), and was promoted by the Italian Communist Party (PCI). The outskirts of Milan were full of impoverished children, and Noce asked her PCI comrades in Reggio Emilia if they would be willing to host some of the children during the upcoming winter. Reggio Emilia offered to host 2,000 children. Other cities in Emilia-Romagna followed suit, including Parma, Piacenza, Modena, Bologna, and Ravenna. On 16 December 1945, the first train departed from Milan and traveled to Reggio Emilia, carrying 1,800 children. Early trains also departed from Turin.
At the , it was decided to shift the focus of the initiative to southern Italy, which was poorer and less developed than the north. That year, 12,000 Neapolitan children boarded trains to the north to spend the winter with host families. Between 1945 and 1952, around 70,000 children from Lazio, Campania, Apulia, Calabria, Sicily, and Sardinia were hosted by families in Emilia-Romagna, Tuscany, Marche, Veneto, and Lombardy in northern Italy. The host families were not wealthy by any means, but were still willing to feed and house the children. The majority of the children would eventually return home, but still maintained relationships with their host families in the subsequent years. In addition to the UCI and the PCI, the initiative was supported by the ANPI, CGIL, and Italian Red Cross.
In popular culture
In 2019, Viola Ardone published Il treno dei bambini, a novel about a young Neapolitan boy who travels to northern Italy on the treni della felicità. It was adapted into a Netflix film, The Children's Train, which premiered in 2024.
See also
Southern question
Orphan Train, a similar program in the United States
References
Further reading
Articles
Books
1940s in Italy
1945 establishments in Italy
1952 disestablishments in Italy
20th century in Emilia-Romagna
20th century in Naples
Adoption, fostering, orphan care and displacement
Aftermath of World War II in Italy
Child welfare in Italy
Communism in Italy
History of rail transport in Italy
Trains | Treni della felicità | [
"Technology"
] | 499 | [
"Trains",
"Transport systems"
] |
78,042,970 | https://en.wikipedia.org/wiki/GS-NDG-9422 | GS-NDG-9422 is a nebular dominated galaxy in the constellation Fornax that was discovered by NASA’s James Webb Space Telescope. Scientists assume that the galaxy's light comes mostly from superheated gas (more than 80 000 degrees Celsius).
References
Galaxies
Emission nebulae
Fornax | GS-NDG-9422 | [
"Astronomy"
] | 68 | [
"Galaxy stubs",
"Galaxies",
"Astronomy stubs",
"Constellations",
"Nebula stubs",
"Fornax",
"Astronomical objects"
] |
78,044,510 | https://en.wikipedia.org/wiki/SW%20Virginis | SW Virginis is a star in the equatorial constellation of Virgo, abbreviated SW Vir. It is a variable star that ranges in brightness from an apparent visual magnitude of 6.65 down to 7.95, with a pulsation period of 153.8 days. The star is located at a distance of approximately 590 light years from the Sun based on parallax measurements, but is drifting closer with a radial velocity of −16 km/s. SW Vir is located near the ecliptic and is subject to lunar occultation, which has allowed its angular diameter to be directly measured.
The variability of this star was discovered by W. P. Fleming and announced in 1901, when it was known as BD −02° 3653. It was given its variable star designation, SW Virginis, in 1912. The star was initially catalogued as an irregular variable but later was classed as a semi-regular variable of type SRb. The stellar classification of M7III: indicates this is an evolved red giant, with the trailing colon indicating some uncertainty about the classification. In 2003, the isotope 99Tc was detected in the atmosphere of SW Vir. The short lifespan of this element is an indicator that the star is undergoing the third dredge-up during the thermally pulsating phase of the asymptotic giant branch (AGB).
This is an oxygen-rich non-Mira AGB star that is shedding mass at a rate of ·yr−1. An infrared excess indicates the star has a circumstellar dust envelope consisting of grains of matter that have condensed out of expelled gas. This dust shell displays an asymmetric appearance. Polarization of light from these dust grains indicate a typical size of less than a μm. The shell's thermal (non-maser) mm-wave spectral line emission from carbon monoxide was detected in 1986, and showed that the circumstellar envelope is expanding at 8.6 km/sec. The spectrum of molecular water has been detected in the star's extended outer atmosphere – out to twice the stellar radius – with a column density of .
References
M-type giants
Semiregular variable stars
Asymptotic-giant-branch stars
Virgo (constellation)
Durchmusterung objects
064569
114961
Virginis, SS | SW Virginis | [
"Astronomy"
] | 482 | [
"Virgo (constellation)",
"Constellations"
] |
78,045,164 | https://en.wikipedia.org/wiki/Neknampur%20Lake | Neknampur Lake, also known as Ibrahim Bagh Cheruvu, is a lake in Hyderabad, India. It was once part of a water reservoir network that was used for irrigation and providing drinking water in the surrounding areas.
History
The lake was first dug up in the late 16th century by Ibrahim Qutb Shah, the fourth ruler of Golconda, and later flooded by his grandson Abdullah Qutb Shah. The construction was entrusted to Neknam Khan, one of Shah's courtiers. Rather than using water from the adjacent Musi, Neknam Khan commissioned channels to fill the lake from water bodies behind the Golconda Fort. Neknampur Lake is one of the three major lakes that were created during the reign of Quli Qutub Shah alongside Ibrahimpatnam Lake and Hussainsagar. There was a proposal by Greater Hyderabad Municipal Corporation to use the lake to dump sewage from surrounding housing colonies. The lake is today divided into two parts known as Chinna Cheruvu, which is smaller, and Pedda Cheruvu, which is larger. The Chinna Cheruvu has been partially restored and converted into a scenic spot whereas the Pedda Cheruvu continues to struggle with pollution. The lake is polluted with various chemicals and also used as a garbage dump by the residential colonies surrounding it. Encroachments and illegal structures surrounding the lake were demolished by government authorities. However these structures are being illegally rebuilt by the encroachers.
Restoration efforts
The lake was gradually occupied by land grabbers and converted into a dump yard for construction debris, garbage, sewage discharge and covered in water hyacinth. At one stage, the surface area of the lake was less than . Efforts to restore the lake were undertaken in 2016 with the help of NGOs based in Hyderabad. The restoration and rejuvenation of the lake included cleaning the lake and floating wetland treatment to tackle the growth of water hyacinth. Contaminants were removed using plants and with the use of microorganisms. NITI Aayog has recognised these efforts and "it has been identified as a role model for 'best restoration practices' in the country." Neknampur Lake restoration "has been recognised as a role model in the 'watershed development' category along with four other projects" in India. According to Niti Aayog, there has been a 90% reduction in Biochemical Oxygen Demand (BOD) of the lake. Centre for Science and Environment (CSE) has also recognised Neknampur Lake "as the best model of lake restoration in India."
Reference
Nature conservation in India
Lakes of Hyderabad, India
Water conservation in India
Ecological restoration
Water pollution in India | Neknampur Lake | [
"Chemistry",
"Engineering"
] | 555 | [
"Ecological restoration",
"Environmental engineering"
] |
78,046,260 | https://en.wikipedia.org/wiki/3C%20346 | 3C 346 is an elliptical galaxy located in the constellation Hercules. It is located nearly 2.5 billion light years away from Earth and classified a Seyfert galaxy and a compact steep-spectrum source (CSS), although later studies confirm it as a Fanaroff-Riley class II source.
Characteristics
3C 346 is classified a narrow-line radio galaxy. It has a projected 0.5-3 keV luminosity of 1.4 x 1044 ergs s−1. The galaxy has a lack of X-ray emission given most of it originates from a cluster environment with a temperature of 1.9+1.3-0.7. It is part of a double galaxy system where the object is found merging with a nearby companion galaxy. 3C 346 also contains a jetted double radio source when observed in X-rays and a bright hotspot region showing strong emission in ultraviolet, mainly caused by synchrotron radiation.
The point-like emission of 3C 346 is found to be unabsorbed, measuring NH ≤ 2 x 1021 cm−2 with a spectral slope of αx = 0.69+0.16-0.14 and flux of 7.4 x 10−13 erg cm−2 s−1 when observed by ROSAT PSPC observations. However, when observed by the Advanced Satellite for Cosmology and Astrophysics (ASCA) two years later, the emission presents a different spectral slope of αx = 0.73+0.17-0.23 with a lower flux level of 7.4 x 10−13 erg cm−2 s−1.
The nucleus of 3C 346 is found to be luminous. It contains a core component in which a one-sided radio jet is seen emerging with a projected extension of around ~ 2 arcsecs, hinting the jet's inclination to the line of sight has a tiny angle. Reaching at high radio frequencies, the jet of 3C 346 contains individual bright knots located at different positions with increased distances from the core region.
According to the jet being detected using Hubble Space Telescope optical polarimetry, Very Large Array polarimetry at 14.9 and 22.5 GHz and data from Chandra X-ray observatory, it shows similarities between optical and radio morphology. However the X-ray emission is found offset by 0.80 ± 0.17 kiloparsecs from both optical and radio peak positions. Based on polarization modeling, the jet of 3C 346 has a relativistic upstream flow of βu = 0.91+0.05-0.07 with an inclined shock front plane angle of η = 51° ± 11° and upstream flow angle of θ = 14+8−7 degrees. The deflection angle of the jet on the other hand, is 22°.
There is also the presence of an extended structure with an extent of ~ 12" around the jet and its opposite side. When observed at 1.7 GHz, the region has two other components with an estimated separation of ~ 2".2. One of the components is found to be stronger and compacted, while the other component is merely a glowing knot inside the jet and mainly surrounded by extended emission.
References
External links
3C 346 on SIMBAD
0346
Hercules (constellation)
Radio galaxies
17.70
058857
Seyfert galaxies
Elliptical galaxies | 3C 346 | [
"Astronomy"
] | 701 | [
"Hercules (constellation)",
"Constellations"
] |
78,046,811 | https://en.wikipedia.org/wiki/2024%20Beirut%20medical%20center%20airstrike | On 4 October 2024, the Israel Defense Forces struck a medical center in central Beirut with an airstrike, amid the 2024 Israeli invasion of Lebanon, killing at least nine and injuring more than 14. Seven members of the medical staff were killed, including two medics, according to a civil defence group linked to Hezbollah. Israel allegedly used white phosphorus to attack the medical center.
Airstrike
The airstrike took place in the early hours of 4 October 2024. The Israeli attack on the medical center caused a fire to erupt in an apartment in the residential Bashoura district, close to the United Nations headquarters in Lebanon, the prime minister's office, and the Lebanese parliament. The medical center, located at the second floor on a 12 storey building, belonged to the Islamic Health Organization, which was linked to Hezbollah. According to human rights experts, affiliations with Hezbollah and Amal do not affect the protected status of hospitals under international law. Israel said it targeted Hezballah "assets", but did not issue an evacuation order prior to the strike.
Use of white phosphorus
Lebanese residents reported a smell that resembled sulfur following the airstrike. The Lebanese state-run National News Agency accused Israel of an illegal use of White phosphorus munition under international law.
Reactions
The strike was condemned as a violation of international law by the foreign chief of the European Union, Josep Borrell, who said the IDF had "targeted once again healthcare workers" and killed civilians in a densely populated area.
References
2024 building bombings
Airstrikes during the 2024 Israeli invasion of Lebanon
October 2024 events in Lebanon
Israeli airstrikes in Lebanon
Israel–Hezbollah conflict (2023–present)
Building bombings in Beirut
2020s crimes in Beirut
Beirut in the Israeli–Lebanese conflict
Wartime hospital bombings in Asia
Attacks on hospitals during the Arab–Israeli conflict
Israeli war crimes in Lebanon
Mass murder in 2024
21st-century mass murder in Lebanon
Mass murder in Beirut
October 2024 crimes in Asia
Beirut airstrikes
Military operations involving chemical weapons
White phosphorus
Attacks on hospitals in Lebanon
Military operations involving incendiary weapons | 2024 Beirut medical center airstrike | [
"Chemistry"
] | 426 | [
"Military operations involving chemical weapons"
] |
78,049,227 | https://en.wikipedia.org/wiki/X%20Ophiuchi | X Ophiuchi is a binary star system in the equatorial constellation of Ophiuchus, abbreviated X Oph. It is a Mira variable that ranges in brightness from an apparent visual magnitude of 5.9 down to 9.2 with a period of 328.85 days. The system is located at a distance of approximately 630 light years from the Sun based on parallax measurements, but is drifting closer with a radial velocity of −71 km/s.
This star was found to be variable by T. H. E. C. Espin in 1886. The binary nature of this system was reported by W. J. Hussey in 1900, listing an angular separation of along a position angle of 195.2°. L. Campbell used light curves of the star from 1904 to 1921 to find a variability period of 337 days. In 1922, G. Van Biesbroeck showed that only the northward member of the pair is variable. P. W. Merrill in 1923 found a stellar classification of M6e for the variable component at maximum, while the secondary is K0. At minimum, the primary becomes fainter than the secondary.
By 1959, the orbital arc of the pair had spanned an angle of 50°, providing an estimated orbital period of at least 500 years and a separation of . Preliminary orbital models suggested a mass of for the variable component and for the K-type giant. The latter star showed an age of around five billion years. At that mass, the variable component must have undergone significant mass loss in order to have already evolved away from the main sequence. The K-type component may have received up to from the donor star.
A 2007 model gives an orbital period of about 877 years with an eccentricity (ovalness) of 0.45. The variable component is an oxygen-rich M-type Mira variable. The duration, amplitude, and shape of the light curve is found to vary slightly from cycle to cycle. Some show a hump during the ascending curve. Its estimated mass loss rate is ·yr−1. In 1992, a strong radio flare event was observed from this system at a frequency of . This outburst came from an OH maser in the inner part of a shell surrounding the variable. Water in the shell is being photodissociated to create OH molecules.
References
M-type giants
K-type giants
Mira variables
Binary stars
Ophiuchus
Durchmusterung objects
172171
091389
Ophiuchi, X | X Ophiuchi | [
"Astronomy"
] | 508 | [
"Ophiuchus",
"Constellations"
] |
78,052,150 | https://en.wikipedia.org/wiki/EndoMac%20progenitor%20cell | EndoMac progenitor cells are a type of endothelial-macrophage progenitor cells, more specifically a population of hemangioblasts from postnatal tissue. They were discovered by Australian researchers in the aorta of mice.
References
Cell biology
Stem cells | EndoMac progenitor cell | [
"Biology"
] | 59 | [
"Cell biology"
] |
78,052,984 | https://en.wikipedia.org/wiki/Petia%20Vlahovska | Petia Mladenova Vlahovska (born circa 1973) is a Bulgarian engineer specializing in biophysics and fluid mechanics. A 2019 Fellow of the American Physical Society and 2024 Guggenheim Fellow, she is a professor at the McCormick School of Engineering Department of Engineering Sciences and Applied Mathematics.
Biography
Vlahovska was born in around 1973 to engineer parents. Moving from her native northern Bulgaria, she obtained her MSc (1994) in Chemistry at Sofia University, where she later started her postgraduate studies as a research associate at their Laboratory of Chemical Physics and Engineering. She later moved across the Atlantic Ocean to Yale University, where she obtained her MS in Chemical Engineering (1999), MPhil in Mechanical Engineering (2001), and PhD in Chemical Engineering (2003); her doctoral dissertation Dynamics of a surfactant-covered drop and the non-Newtonian rheology of emulsions was supervised by Jerzy Blawzdziewicz and Michael Loewenberg. She was later a David Crighton Fellow (2004-2005) at the University of Cambridge Department of Applied Mathematics and Theoretical Physics.
After visiting positions as an assistant professor at the Brown University School of Engineering (2003-2005) and a scientist at the Max Planck Institute of Colloids and Interfaces Theory and Bio-systems Department (2005-2006), she moved to Dartmouth College's Thayer School of Engineering in 2006 and became assistant professor. In 2010, she returned to Brown, while retaining an adjunct assistant professor position at the Thayer School of Engineering until 2011 and Dartmouth's department of physics until 2012; she was promoted from assistant professor to associate professor in 2013. She moved to Northwestern University (where she had been a visiting scholar from 2014 to 2015) in 2017 and was promoted there to professor in 2020. At Northwestern, she has also been part of the Northwestern-Argonne Institute of Science and Engineering.
She and her research group research biological and physical systems through theoretical and experimental models. She teaches classes in fluid mechanics and biophysics, as well as in applied mathematics and vector calculus. In 2016, she was awarded the Humboldt Research Award. In 2019, she was elected Fellow of the American Physical Society for "pioneering work on problems in interfacial flows and soft matter, including the fluid-structure interaction in Stokes flow, the mechanics of biomembranes, and electrohydrodynamics." She was awarded a Guggenheim Fellowship in 2024; she intends to use the Fellowship to do research on the use of active fluids in cytological microbotics.
References
1970s births
Living people
Bulgarian engineers
21st-century women engineers
Biophysicists
21st-century Bulgarian physicists
Bulgarian women physicists
Women biophysicists
Fluid dynamicists
Sofia University alumni
Yale University alumni
Brown University faculty
Max Planck Institutes researchers
Thayer School of Engineering faculty
Northwestern University faculty
Fellows of the American Physical Society
Humboldt Research Award recipients
Bulgarian expatriates in the United States
Expatriate academics in the United States | Petia Vlahovska | [
"Chemistry"
] | 599 | [
"Fluid dynamicists",
"Fluid dynamics"
] |
78,053,249 | https://en.wikipedia.org/wiki/Weight%20initialization | In deep learning, weight initialization describes the initial step in creating a neural network. A neural network contains trainable parameters that are modified during training: weight initialization is the pre-training step of assigning initial values to these parameters.
The choice of weight initialization method affects the speed of convergence, the scale of neural activation within the network, the scale of gradient signals during backpropagation, and the quality of the final model. Proper initialization is necessary for avoiding issues such as vanishing and exploding gradients and activation function saturation.
Note that even though this article is titled "weight initialization", both weights and biases are used in a neural network as trainable parameters, so this article describes how both of these are initialized. Similarly, trainable parameters in convolutional neural networks (CNNs) are called kernels and biases, and this article also describes these.
Constant initialization
We discuss the main methods of initialization in the context of a multilayer perceptron (MLP). Specific strategies for initializing other network architectures are discussed in later sections.
For an MLP, there are only two kinds of trainable parameters, called weights and biases. Each layer contains a weight matrix and a bias vector , where is the number of neurons in that layer. A weight initialization method is an algorithm for setting the initial values for for each layer .
The simplest form is zero initialization:Zero initialization is usually used for initializing biases, but it is not used for initializing weights, as it leads to symmetry in the network, causing all neurons to learn the same features.
In this page, we assume unless otherwise stated.
Recurrent neural networks typically use activation functions with bounded range, such as sigmoid and tanh, since unbounded activation may cause exploding values. (Le, Jaitly, Hinton, 2015) suggested initializing weights in the recurrent parts of the network to identity and zero bias.
In most cases, the biases are initialized to zero, though some situations can use a nonzero initialization. For example, in multiplicative units, such as the forget gate of LSTM, the bias can be initialized to 1 to allow good gradient signal through the gate. For neurons with ReLU activation, one can initialize the bias to a small positive value like 0.1, so that the gradient is likely nonzero at initialization, avoiding the dying ReLU problem.
Random initialization
Random initialization means sampling the weights from a normal distribution or a uniform distribution, usually independently.
LeCun initialization
LeCun initialization, popularized in (LeCun et al., 1998), is designed to preserve the variance of neural activations during the forward pass.
It samples each entry in independently from a distribution with mean 0 and variance . For example, if the distribution is a continuous uniform distribution, then the distribution is .
Glorot initialization
Glorot initialization (or Xavier initialization) was proposed by Xavier Glorot and Yoshua Bengio. It was designed as a compromise between two goals: to preserve activation variance during the forward pass and to preserve gradient variance during the backward pass.
For uniform initialization, it samples each entry in independently and identically from . In the context, is also called the "fan-in", and the "fan-out". When the fan-in and fan-out are equal, then Glorot initialization is the same as LeCun initialization.
He initialization
As Glorot initialization performs poorly for ReLU activation, He initialization (or Kaiming initialization) was proposed by Kaiming He et al. for networks with ReLU activation. It samples each entry in from .
Orthogonal initialization
(Saxe et al. 2013) proposed orthogonal initialization: initializing weight matrices as uniformly random (according to the Haar measure) semi-orthogonal matrices, multiplied by a factor that depends on the activation function of the layer. It was designed so that if one initializes a deep linear network this way, then its training time until convergence is independent of depth.
Sampling a uniformly random semi-orthogonal matrix can be done by initializing by IID sampling its entries from a standard normal distribution, then calculate or its transpose, depending on whether is tall or wide.
For CNN kernels with odd widths and heights, orthogonal initialization is done this way: initialize the central point by a semi-orthogonal matrix, and fill the other entries with zero. As an illustration, a kernel of shape is initialized by filling with the entries of a random semi-orthogonal matrix of shape , and the other entries with zero. (Balduzzi et al., 2017) used it with stride 1 and zero-padding. This is sometimes called the Orthogonal Delta initialization.
Related to this approach, unitary initialization proposes to parameterize the weight matrices to be unitary matrices, with the result that at initialization they are random unitary matrices (and throughout training, they remain unitary). This is found to improve long-sequence modelling in LSTM.
Orthogonal initialization has been generalized to layer-sequential unit-variance (LSUV) initialization. It is a data-dependent initialization method, and can be used in convolutional neural networks. It first initializes weights of each convolution or fully connected layer with orthonormal matrices. Then, proceeding from the first to the last layer, it runs a forward pass on a random minibatch, and divides the layer's weights by the standard deviation of its output, so that its output has variance approximately 1.
Normalization-free initialization
In 2015, the introduction of residual connections allowed very deep neural networks to be trained, much deeper than the ~20 layers of the previous state of the art (such as the VGG-19). Residual connections gave rise to their own weight initialization problems and strategies.
Fixup initialization is designed specifically for networks with residual connections and without batch normalization, as follows:
Initialize the classification layer and the last layer of each residual branch to 0.
Initialize every other layer using a standard method (such as He initialization), and scale only the weight layers inside residual branches by .
Add a scalar multiplier (initialized at 1) in every branch and a scalar bias (initialized at 0) before each convolution, linear, and element-wise activation layer.
Similarly, T-Fixup initialization is designed for Transformers without layer normalization.
Others
Instead of initializing all weights with random values on the order of , sparse initialization initialized only a small subset of the weights with larger random values, and the other weights zero, so that the total variance is still on the order of .
Random walk initialization was designed for MLP so that during backpropagation, the L2 norm of gradient at each layer performs an unbiased random walk as one moves from the last layer to the first.
Looks linear initialization was designed to allow the neural network to behave like a deep linear network at initialization, since . It initializes a matrix of shape by any method, such as orthogonal initialization, then let the weight matrix to be the concatenation of .
Miscellaneous
For hyperbolic tangent activation function, a particular scaling is sometimes used: . This was sometimes called "LeCun's tanh". It was designed so that it maps the interval to itself, thus ensuring that the overall gain is around 1 in "normal operating conditions", and that is at maximum when , which improves convergence at the end of training.
In self-normalizing neural networks, the SELU activation function with parameters makes it such that the mean and variance of the output of each layer has as an attracting fixed-point. This makes initialization less important, though they recommend initializing weights randomly with variance .
History
Random weight initialization was used since Frank Rosenblatt's perceptrons. An early work that described weight initialization specifically was (LeCun et al., 1998).
Before the 2010s era of deep learning, it was common to initialize models by "pre-training" using an unsupervised learning algorithm that is not backpropagation, as it was difficult to directly train deep neural networks by backpropagation. For example, a deep belief network was trained by using contrastive divergence layer by layer, starting from the bottom.
(Martens, 2010) proposed a quasi-Newton method to directly train deep networks. The work generated considerable excitement that initializing networks without pre-training phase was possible. However, a 2013 paper demonstrated that with well-chosen hyperparameters, momentum gradient descent with weight initialization was sufficient for training neural networks, a combination that is still in use as of 2024.
Since then, the impact of initialization on tuning the variance has become less important, with methods developed to automatically tune variance, like batch normalization tuning the variance of the forward pass, and momentum-based optimizers tuning the variance of the backward pass.
There is a tension between using careful weight initialization to decrease the need for normalization, and using normalization to decrease the need for careful weight initialization, with each approach having its tradeoffs. For example, batch normalization causes training examples in the minibatch to become dependent, an undesirable trait, while weight initialization is architecture-dependent.
See also
Backpropagation
Gradient descent
Vanishing gradient problem
References
Further reading
Machine learning
Artificial neural networks
Deep learning | Weight initialization | [
"Engineering"
] | 1,969 | [
"Artificial intelligence engineering",
"Machine learning"
] |
76,641,623 | https://en.wikipedia.org/wiki/Nanette%20Wylde | Nanette Wylde is an American artist and writer. Wylde is known for her early incorporation of digital media as a fine art media, her work in net.art, electronic literature, and artwork which takes book form.
Wylde makes works which are interdisciplinary, conceptual, narrative, and often involve collaboration with other artists. She works in many media including artist books, digital and electronic media, installation, printmaking, and social practice.
Early life and education
Wylde was born in California and grew up in San Jose.
Wylde's education includes an MFA from the Ohio State University where she studied interactive multimedia and printmaking (1996), a Bachelor's from San Jose State University in Behavioral Science (1986), and an Associate degree from West Valley College in Saratoga, California (1981).
Wylde claims her early influences to be artists Laurie Anderson, Jenny Holzer, Cindy Sherman, Ann Hamilton, Christine Tamblyn, and studying with Rupert Garcia at San Jose State University.
Career
Wylde is a narrative artist with focus on storytelling with socio-cultural content. Many of her works are about stereotyping and involve cultural critique. Her themes include re-interpreting historical perspectives, and the reliability of information-based media. Later works have an environmental focus. She often includes audience participatory elements in her projects which allow participants to contribute to the works in meaningful and permanent ways. Wylde considers herself to be a conceptual artist and calls herself a cultural worker.
Her electronic works have been exhibited internationally.
Many reviewers comment on the humor in Wylde's work. In a discussion of a Jessica Gomula exhibition, Kim De Vries references Wylde, "This irreverence can be found in other artists working today such as Nanette Wylde . . . and reflects a contemporary skepticism about artistic theories and movements as such; a resistance to taking any of this system of artistic production and criticism too seriously.”
Collaboration with other artists is common in Wylde's practice with her primary collaboration partner being Kent Manske. Notable projects Manske and Wylde have worked together on include Foodies, Meaning Maker, Preserves, and You are the Tree.
Her works are taught in university level literature and art classes.
Artist's books
Wylde works in the genre artist's books in which the artwork references or takes book form. She was commissioned by The San Francisco Center for the Book for their first year of small plates book projects in 2008. The book she created is Gray Matter Gardening: how to weed your mind.
Wylde makes books under the imprint Hunger Button Books. Her artist's books have exhibited widely, won awards, and are included in international book arts collections.
Digital media
Wylde began using digital media tools, Photoshop and Painter software, to create images in 1991. She often combined software with traditional printmaking such as lithography and relief printing. Her work is included in several early software (Photoshop and Painter) publications.
Wylde began working in interactive multimedia in 1994 while studying at Ohio State University's Advanced Computing Center for Art and Design. Her graduate thesis project was an interactive multimedia artwork titled A Brief History. The project was feminist in content, focusing on women's history and celebrating female diversity. The project included an interactive installation of images mounted on small wood blocks which the audience could move about on a series of small shelves to create their own narratives.
Electronic works and net.art
Wylde creates net.art projects and electronic projects which required a computer to be experienced, most frequently in an electronic flipbook format. Her electronic projects often allow audience input. Many use the computer's random function.
Carolyn Guertin writes about Wylde's electronic flipbooks, Arrested, Belief Manifesto and haikU, “Drawing from three different data streams, these texts recombine them to create instant works of art from a community experience. Arrested works along similar lines but more closely shows a genealogy with text-based experiments by feminist artists like Jenny Holzer and Barbara Kruger. Exploring our expectations of social posturing and the politics of rhetoric, Arrested toys with our expectations. Combining racial and ethnic groups with the politics of everyday activities, the texts consistently test our assumptions and challenges us to rethink them. While Arrested does not require the reader to input material, it does work to restate the reader in relation to the material she is reading. In short, It requires us to change our perspective and insert ourselves into the textual community to experience new points of view.”
Elizabeth Joe writes about Wylde's 2003 net.art project The Daily Planet Interactive: "In this project, she specifically parodies information delivery systems and (American) media culture. It is an interactive Net art project that aims to foster a new viewer outlook with respect to cultural identity and accepted social practices that are one-sided.” AND "Wylde addresses the ideas of society being consumed with the need to attain information by partially obscuring information from the viewer. Moreover, she continues to cleverly play with viewer expectations for she does not allow the headlines to run consistent with the newspaper format headings. In both respects, the viewers’ expectations are not met – they do not receive the information they want. These ideas closely mimic Wylde's underlying theme of how the media controls/manipulates information and only disseminates information they think should be important to the masses.” Joe continues, "It is also important to note Wylde’s tactic with respect to further addressing the idea that the media only distributes one-way communication to its viewers. Newspapers can be perceived as a social construction that propagates information for a specific purpose. Through her web project viewers are afforded 'two-way communication' where they are free to not only take in media headlines and personal entries, but are also afforded the opportunity to voice their questions and opinions.”
Wylde's electronic project Storyland is included in the first Electronic Literature Collection published by the Electronic Literature Organization.
Social Practice
Wylde works in the art genre of social practice. Her Meaning Maker project, which are free fill-out-form pamphlets on different subjects is one example. She works in the community by creating opportunities for other artists in the form of exhibitions and publications. Exhibitions Wylde has curated include Eco Echo at WORKS San Jose and Gallery Route One in Pt. Reyes Station, California; Pathways at Art Ark in San Jose, California; Biophilia at WORKS San Jose; Conceptually Bound at California State University in Chico and at The Mohr Gallery in Mountain View, California; The Legacy of Jo Hanson at Yolo Arts in Woodland, California. She creates publications featuring other artists' work in the form of exhibition catalogs and an annual anthology titled Entanglements.
Curator Gregory Flood says of the social practice project Preserves, "Kent Manske and Nanette Wylde created a large-scale participatory piece. What it looks like is a giant mason jar with the word “preserves” written across it. And they invite viewers to write on a little tag with a little string on it. And they write on it something that they would love to preserve as part of their culture or their food, and then they tie it on to that board. So it’s a really wonderful community engagement piece."
Works
A Brief History . . ., interactive multimedia installation, 1996
Arrested, electronic flipbook, 1997
about so many things, electronic flipbook, 1998
Storyland, electronic literature, net.art, 2000
haikU, digital poetry generator, electronic literature, net.art, 2001
The Daily Planet Interactive, net.art, 2003
ebaybies: genuine and lasting friends, conceptual series of intaglio prints, 2003–2004
Jargon Reducer, net.art, 2005
Meaning Maker, social practice project, democratic multiple, net.art, installation, 2006
Gray Matter Gardening: How to weed your mind, artist's book, San Francisco Center for the Book, 2008
On Judgment: the book of bully, artist's book, 2012
Preserves, with Kent Manske, sculpture and installation, 2015
Foodies: Seven West Coast Foodie Vignettes, with Kent Manske, artists' book, 2017
You Are The Tree, with Kent Manske, sculpture and installation, 2020
Encyclopedic: Weathered Volumes, conceptual book works, 2023
Leaving Digital, electronic literature, net.art, 2023
Collections
Achenbach Foundation for Graphic Arts, Fine Arts Museums of San Francisco, San Francisco, California
Almutanabbi Street Starts Here archive, Rare Book and Manuscript Library, Butler Library, Columbia University, New York, New York
Baylor University Libraries, Waco, Texas
Boise State University Albertson's Library
Decker Library, Maryland Institute College of Art
Duke University Library, Durham, NC
George Mason University, Fenwick Library, Fairfax, VA
Harvard University Fine Arts Library, Cambridge, MA
MIT Libraries, Cambridge, MA
Olin Library, Cornell University, Ithica, New York
San Francisco Public Library, San Francisco, CA
Santa Clara University, Santa Clara, CA
Savannah College of Art and Design, Jen Library, Savannah, GA
Staatsbibliothek zu Berlin – Preußischer Kulturbesitz, Haus Potsdamer Straße, Berlin, Germany
Stanford University Libraries, Stanford, California
The Center for the Study of the Book, The Bodleian Libraries, University of Oxford, Oxford, United Kingdom
Tufts University Tisch Library, Medford, MA
University of California, Berkeley: Artists' Books Collection
UC Davis Shields Library, Davis, CA
UC Santa Cruz, Santa Cruz, CA
University of Colorado Boulder, Boulder, CO
University of Iowa Library, Iowa City, Iowa
University of Michigan, Ann Arbor, MI
University of Pennsylvania Libraries, Philadelphia, PA
University of Washington Libraries, Seattle, Washington
References
External links
Digital Visions interview by Elizabeth Joe
Living people
20th-century American artists
20th-century American women artists
21st-century American artists
21st-century American women artists
21st-century American writers
21st-century American women writers
American conceptual artists
American digital artists
American electronic literature writers
American feminist artists
American new media artists
American printmakers
American women printmakers
Artists from the San Francisco Bay Area
Book artists
California State University, Chico faculty
Electronic literature writers
Net.artists
Ohio State University Graduate School alumni
People from San Jose, California
San Jose State University alumni
Women book artists
Women digital artists
Year of birth missing (living people) | Nanette Wylde | [
"Technology"
] | 2,136 | [
"Multimedia",
"Net.artists"
] |
76,641,725 | https://en.wikipedia.org/wiki/NGC%202606 | NGC 2606 is a spiral galaxy located around 646 million light-years away in the constellation Ursa Major. NGC 2606 was discovered on February 16th, 1831 by the astronomer John Herschel, and it has a diameter around 232,000 light-years. NGC 2606 is known to have some star-formation, and it is known to have an active galactic nucleus, specifically a Type II Seyfert galaxy.
References
External links
2606
Spiral galaxies
Ursa Major
24117
LINER galaxies
Seyfert galaxies
Astronomical objects discovered in 1831
Discoveries by John Herschel | NGC 2606 | [
"Astronomy"
] | 117 | [
"Ursa Major",
"Constellations"
] |
76,642,119 | https://en.wikipedia.org/wiki/ATRenew | ATRenew (formerly AiHuiShou) is a Chinese company established in 2011 and headquartered in Shanghai, founded by Kerry Xuefeng Chen. ATRenew operates two main business segments: a second-hand product trade and service system, and an urban green industry chain business. The company has several subsidiaries, including AHS Recycle, and maintains a strategic partnership with JD.com, which was its largest investor prior to ATRenew’s rebranding. ATRenew is traded on the NYSE.
History
The company launched in 2011 as ATRenew as a recycling service for mobile phones. Over time, it expanded its focus to include a broader range of consumer electronics, gradually increasing its physical and online presence across China. In 2015, AiHuiShou began collaborating on trade-in programs with JD.com and Xiaomi.
In 2017, AiHuiShou started automating its operational systems and established an operation center in Changzhou. In 2018, AiHuiShou launched a B2B trading platform for pre-owned consumer electronics.
In June 2019, AiHuiShou integrated JD.com’s Paipai Marketplace, enabling AiHuiShou to manage JD.com’s second-hand, idle, inventory, and resale businesses within the 3C (computer, communication, and consumer electronics) categories. On September 22, 2020, AiHuiShou rebranded to ATRenew (All Things Renew) and launched AHS Recycle, offering recycling services through chain stores, self-service kiosks, and online platforms.
On June 18, 2021, ATRenew went public on the NYSE. In 2022, ATRenew’s largest and most automated facility, the Dongguan Automation Operation Center, began operating. By the end of 2022, ATRenew had established eight major regional operation centers, located in Dongguan, Changzhou, Wuhan, Chengdu, Tianjin, Xi’an, Shenyang, and Hong Kong. In the second quarter of 2022, ATRenew launched its “multi-category” strategy, expanding its recycling services to include photographic equipment, bags, watches, gold, prestige liquors, shoes, and other items through its physical stores.
In June 2023, ATRenew began collaborating with Apple Inc. for its recycling and trade-in services available on Apple’s official website and in offline flagship stores across China. In the same year, ATRenew joined the United Nations Global Compact (UNGC).
Funding
The company had a financing round in 2018 securing $150 million in investment led by Tiger Global Management and JD.com valuing the company at over $1.5 billion. By February 2021, the company raised $200 million in pre-IPO fundraising. On 22 September 2022, after rebranding, the company announced that it had raised over $100 million in E+ round of financing with JD.com – its biggest investor which acquired 34% of ordinary shares before offering. Other investors included Huihe Capital, InnoVen Capital and Shanghai Prosperity Fund with Taihe Capital serving as its exclusive financial adviser for the E+ round of funding.
Business lines
ATRenew operates several business lines, including AHS Recycle, PJT Marketplace, Paipai Marketplace, AHS Device, and LOVERE (AiFenLei).
AHS Recycle is a C2B recycling and trade-in platform offering recycling services to consumers and collaborating with partners like JD.com and Apple for trade-in services. As of the end of 2023, AHS Recycle has expanded across 268 cities in China through a network of 1,819 offline AHS stores.
PJT Marketplace serves as a B2B platform where businesses can buy and sell secondhand electronics. It also provides price assessment services to assist both buyers and sellers in making informed transactions.
Paipai Marketplace has assumed responsibility for the second-hand, idle, inventory, and resale operations of 3C (computer, communication, and consumer electronics) categories on JD.com. It functions as a B2C retail platform, facilitating the re-commercialization of premium pre-owned consumer electronics.
AHS Device represents ATRenew’s overseas expansion, with operations in regions including Southeast Asia, Latin America, and Africa. It has invested in mobile phone recycling companies, such as India’s Cashify and Brazil’s Trocafone. In Japan, AHS Device has partnered with Janpara to place self-service recycling kiosks, and it has collaborated with Finland-based Swappie to do the same in Sweden.
LOVERE (AiFenLei) specializes in garbage sorting and trash recycling services, designed to encourage households to increase their recycling efforts through financial incentives. It provides intelligent recycling machines and comprehensive waste management solutions. The LOVERE kiosks accept recyclable waste, rewarding users with credits on the WeChat app as an incentive.
References
External links
Recycling in China
Companies of China
E-commerce
Chinese companies established in 2011 | ATRenew | [
"Technology"
] | 1,032 | [
"Information technology",
"E-commerce"
] |
76,642,628 | https://en.wikipedia.org/wiki/NGC%205539 | NGC 5539 is a large lenticular galaxy in the Boötes constellation. It is located 857 million light-years away and was discovered by John Herschel on 24th April, 1830. According to Herschel, he found it quite large and irregular. NGC 5539 is about 273,000 light-years in diameter, meaning it is much larger compared to the Milky Way and its neighbor, the Andromeda Galaxy. It is the brightest cluster galaxy in Abell 1890.
It is said NGC 5539 can be classified as a high surface brightness galaxy with a surface brightness value of 11.40 mag/am2.
References
Lenticular galaxies
Boötes
5539
51054
Astronomical objects discovered in 1830
Discoveries by John Herschel
+01-36-033
51054
J14173775+0810468 | NGC 5539 | [
"Astronomy"
] | 166 | [
"Boötes",
"Constellations"
] |
76,642,746 | https://en.wikipedia.org/wiki/NGC%205535 | NGC 5535 is an elliptical galaxy in the Boötes constellation. It is located 831 million light-years away and was found by Albert Marth, a German astronomer on May 8th,1864.
NGC 5535 has an active galactic nucleus and considered as a radio galaxy according to SIMBAD, in which expels large amounts of radio waves. It is a member of Abell 1890 galaxy cluster and located to the nearby lenticular galaxy, NGC 5539, which is the brightest galaxy member.
References
Radio galaxies
Elliptical galaxies
5535
097424
Boötes
Galaxies discovered in 1864
Astronomical objects discovered in 1864
Discoveries by Albert Marth
J14173129+0812298 | NGC 5535 | [
"Astronomy"
] | 139 | [
"Boötes",
"Constellations"
] |
76,643,162 | https://en.wikipedia.org/wiki/NGC%202688 | NGC 2688 is a spiral galaxy located in Ursa Major. It is located 758 million light-years away from the Solar System and is moving away at a speed of 15,190 km/s. NGC 2688 was found by R.J. Mitchell who was an Irish astronomer and assistant to William Parsons. When Mitchell first saw the object, he commented it as very small and faint. According to Professor Seligman, the galaxy is classified as a lenticular galaxy rather than a spiral galaxy.
References
2688
Spiral galaxies
025048
Ursa Major
+08-16-040
J08551161+4907218
Discoveries by R. J. Mitchell (astronomer) | NGC 2688 | [
"Astronomy"
] | 143 | [
"Ursa Major",
"Constellations"
] |
76,643,247 | https://en.wikipedia.org/wiki/Suberinic%20acid | Suberinic acids are a type of carboxylic acids naturally encountered in the bark of Betula tree species. Chemically, they predominantly have long (C18) chains with α- and ω- bifunctional saturated and unsaturated fatty acid ends. Their name originates from suberin, a major chemical biopolymer of tree bark.
Uses
The outer bark of birch (Betula spp.) tree is abundant in betulin. Upon extracting betulin, the remaining material consists of tissues containing suberin. Suberin is a biopolyester composed of α,ω - bifunctional fatty acids, namely the suberinic acids, which, along with lignocarbohydrate complexes, can serve as a potential adhesive in the form of a byproduct obtained during the extraction of suberinic acids for polyol synthesis. Recent studies have proved the potential application of this product, obtained by depolymerizing suberin, in the wood-based panels such as particleboard utilizing different solvents.
Recently, suberinic acids have found to have new applications in wood industry. The industrial mixture of suberinic acids, obtained from extracted birch outer bark, can be successfully used in industry for adhesion purposes, possibly in wood protection as well.
References
Fatty acids
Organic compound stubs
Wood extracts | Suberinic acid | [
"Chemistry"
] | 277 | [
"Organic compounds",
"Organic compound stubs",
"Organic chemistry stubs"
] |
76,644,068 | https://en.wikipedia.org/wiki/Dimdazenil | Dimdazenil (trade name Junoenil) is a pharmaceutical drug for insomnia. It is a benzodiazepine derivative and a partial positive allosteric modulator of the GABAA receptor with two- to four-fold higher functional affinity for the α1 subunit relative to the α2, α3, and α5 subunits.
Medical use
Dimdezenil shows effectiveness in the treatment of insomnia, but has less intrinsic activity in comparison to currently-marketed benzodiazepines and the Z-drugs; however, it is thought that the lower efficacy may result in fewer side effects, such as motor incoordination. In China, dimdezenil is approved for short-term treatment of insomnia.
History
Dimdezenil was originally developed by Roche, based on preclinical data, as a non-sedating anxiolytic, but was found to produce sedation in humans in phase I clinical trials. For this reason, it was subsequently licensed to Evotec, which is now developing it for the treatment of insomnia. By 2007, dimdezenil completed phase II clinical trials for this indication, with positive findings reported. In China, the drug was developed by Zhejiang Jingxin Pharmaceutical.
References
External links
Dimdazenil - AdisInsight
GABAA receptor positive allosteric modulators
Dimethylamino compounds
Oxadiazoles
Imidazobenzodiazepines
Chloroarenes
Hypnotics
Sedatives | Dimdazenil | [
"Biology"
] | 314 | [
"Hypnotics",
"Behavior",
"Sleep"
] |
76,644,268 | https://en.wikipedia.org/wiki/LEDA%201245565 | LEDA 1245565 (known as RX J1140.1+0307) is a spiral galaxy located 1.04 billion light-years away in the constellation of Virgo. It has a similar structure to the Milky Way, though it has a low black hole mass. It has an active galactic nucleus and is classified as a narrow-line Seyfert 1 galaxy with enhanced star formations.
References
Virgo (constellation)
Spiral galaxies
1245565
J11400874+0307114 | LEDA 1245565 | [
"Astronomy"
] | 109 | [
"Virgo (constellation)",
"Constellations"
] |
76,644,460 | https://en.wikipedia.org/wiki/MCG%20-03-04-014 | MCG -03-04-014 or PGC 4167, is a spiral galaxy located 450 million light-years in the constellation of Cetus. MCG -03-04-014 is classified as a luminous infrared galaxy, meaning it has high star-formation regions. MCG -03-04-014 has a galactic center that is obscured by dust lanes and presents an abundant supply of molecular gas. The reasons behind the luminosity of this galaxy are debated among astronomers. Some attribute it to recent starbursts, while others point to activity in the galaxies' supermassive black holes. It is also considered that both factors may contribute. The exact cause remains uncertain.
According to SIMBAD, it is considered to be a Seyfert type 1 galaxy, hence the possible reason for its luminosity level.
References
Spiral galaxies
-03-04-014
004167
Luminous infrared galaxies
Cetus
J01100897-1651096
IRAS catalogue objects | MCG -03-04-014 | [
"Astronomy"
] | 209 | [
"Cetus",
"Constellations"
] |
76,645,072 | https://en.wikipedia.org/wiki/NEW%20ID | NEW ID is a digital streaming service and television channel established in 2019 that broadcasts Korean entertainment content, including K-dramas, K-pop, and Korean movies. It is available on various international platforms such as Xumo, LG Channels, Pluto TV, and Samsung TV Plus.
History
NEW ID was founded in 2019, initially available on platforms such as Xumo and LG TV. Over time, it expanded its offerings to include Samsung TV Plus, aiming to reach a broader international audience in the US.
Content and Programming
NEW ID broadcasts a variety of Korean programming, ranging from K-dramas and K-pop concerts to classic Korean movies. The service regularly updates its content library and has obtained FAST/AVOD broadcasting rights for several shows and events. Additionally, NEW ID distributes content from other Asian markets, including channels like OnDemand China and Rakuten Viki.
NEW KPOP
NEW KMOVIES
NEW KFOOD
My Little Pet
PINKFONG BABY SHARK TV
RAKUTEN VIKI
ON DEMAND CHINA
World Billiards TV
Toony Planet
MUBEAT
SBS KDrama
ROMCOM K-DRAMA
YTN News
BINGE Korea
BINGE Korea is another streaming service focusing on Korean content. In 2023, it was made available on BMW's in-car systems, allowing vehicle owners to access its content through the multimedia systems. BINGE Korea also expanded its availability in the United States by launching on several major streaming devices and platforms including Samsung, LG, Roku, and Amazon Fire TV.
Launched Platforms (BINGE Korea)
Samsung
LG
Roku
Amazon Fire TV
Xperi on BMW
VIZIO
External links
References
Television networks in South Korea
Streaming television | NEW ID | [
"Technology"
] | 339 | [
"Multimedia",
"Streaming television"
] |
76,646,103 | https://en.wikipedia.org/wiki/Swimming%20pool%20bacteria | Swimming pool bacteria are the diverse array of bacteria that are present in aquatic environments, primarily swimming pools, which can have effects on human health and water quality. Recreational waters are known to be source of infectious diseases.
Types
There are different types of bacteria that are found in swimming pools and other types of recreational waters. The most prevalent of them is Staphylococcus aureus (S. aureus). This bacterium is one of the leading causes of skin infections in the world. Such infections could appear as painful boils and rashes. It is naturally present in humans on skin, in nasal mucous, and inside the intestinal tract. S. aureus has a strong resistance to chlorine, which is one of the methods by which pools are often cleaned.
Other bacteria often found in recreational waters are Enterococci, which is a genus of bacteria found in feces. Fecal contamination is one of the primary public health concerns in swimming pools. Fecal contamination usually occurs through excretion by bathers, other animals, or contaminated water sources.
Levels found in recreational waters
Researchers have studied the quantity of bacteria in recreational waters. In a study of swimming pools in Alexandria, Egypt, the team studied 10 pools, both indoor and outdoor, over two months during the summer. The team found that bacteria seemed to be more prevalent in outdoor pools. Furthermore, they noted that the higher the pH of the pool, the more bacteria were present in the water. 20.2% of the bacteria in the pools were found to be S. aureus.
Another study reported two experiments involving a large pool and a small pool. Using 10 volunteers, the team examined how many bacteria could be found in the watershed by the bathers and how many could be found in the water after the bathers were exposed to sand. The study concluded that bathers shed both S. aureus and enterococci into the water, and S. aureus was shed the most. After each cycle, the number of bacteria the bathers shed decreased.
Enterotoxic Escherichia coli has been found in pools with sub-optimal chlorine levels.
Disease prevention
There are several diseases caused by S. aureus and enterococci. S. aureus has been found to cause sepsis and pneumonia, among other problems, while Enterococci has been found to cause sepsis and urinary tract infections, as well as being resistant to antibiotics. There are various actions taken to prevent swimmers from falling ill. The swimming facilities must ensure that their filtration is working and that their staff are trained and know the appropriate behavior and procedures of the facilities. Individual swimmers must also take preventative measures. As stated by the Centers for Disease Control and Prevention (CDC), guests must not swim if they have diarrhea, swimmers should not swallow pool water, swimmers should wash themselves before entering the pool, and if the restroom is used, each guest must thoroughly wash themselves.
In Europe, the cleanliness of pools is monitored by measuring the levels Escherichia coli, enterococci and Pseudomonas aeruginosa. Staphylococcus aureus levels are not monitored despite the detection of the bacteria in recreational waters (and on beaches). The authors of a 2023 study recommended levels of bacteria of 0 CFU/100 mL for water of excellent quality, less than 20 CFU/100 mL for water of very good quality, less than 50 CFU/100 mL for good quality water, and more than 50 CFU/100 mL for poor quality water.
References
Wikipedia Student Program
Bacteria
Bacteriology
Microorganisms
Swimming pools | Swimming pool bacteria | [
"Biology"
] | 740 | [
"Prokaryotes",
"Microorganisms",
"Bacteria"
] |
76,646,219 | https://en.wikipedia.org/wiki/Population%20Balance | Population Balance (formerly World Population Balance) is a 501(c)(3) non-profit organization in the United States that raises awareness of the connections between pronatalism, human supremacy, social inequalities, and ecological overshoot, and advocates for solutions to address their combined impacts on the planet, people, and animals.
History and background
Population Balance was founded by David Paxson as World Population Balance in 1993. He was succeeded as the executive director in 2016 by Dave Gardner. In 2021 Nandita Bajaj became executive director and the organization adopted its current name of Population Balance and a new vision, mission, and philosophy.
Notable past and present advisors include Nobel Peace Prize laureate Norman Borlaug, former Governor of Michigan William Milliken, originator of the "ecological footprint" concept William E. Rees, actress and activist Alexandra Paul, and physicist Albert Allen Bartlett.
Activities
Activities include The Overpopulation Podcast, classroom and conference presentations, academic and media publications, and media and podcast interviews.
The Overpopulation Podcast
The Overpopulation Podcast is released twice monthly and is ranked in the top 1.5% of podcasts globally. The podcast hosts interview expert guests to explore the drivers and impacts of ecological overshoot as well as individual and collective solutions. Notable guests have included Mechai Viravaidya, Riane Eisler, Paul Ehrlich, Alan Weisman, Naomi Oreskes, William E. Rees, Angela Saini, Partha Dasgupta, Carl Safina, Richard Heinberg, Orna Donath, Robert Jensen, Jo-Anne McArthur, Robert Engelman, Malcolm Potts, Alexandra Paul, Kevin Bales, and Vegard Skirbekk.
References
External links
Ecology organizations
Environmental organizations established in 1993
Non-profit organizations based in the United States
Population concern organizations
Environmental organizations
Population concern advocacy groups
Sustainability organizations
Anti-consumerist groups
Minimalism
Animal rights organizations
Reproductive rights organizations
Women's rights organizations based in the United States
Women's rights organizations
Degrowth
Abortion-rights organizations
Social justice organizations
Vegan organizations
501(c)(3) organizations | Population Balance | [
"Environmental_science"
] | 435 | [
"Degrowth",
"Environmental ethics"
] |
76,646,373 | https://en.wikipedia.org/wiki/Kiso%205639 | Kiso 5639 (also known as LEDA 36252, KUG 1138+327 or the Skyrocket Galaxy) is an irregular dwarf galaxy in the constellation Ursa Major, approximately 85 million light-years from Earth. It has an elongated and flattened shape, with a maximum diameter that extends for approximately 2,700 light years. The new stars are distributed in about ten groups and have a mass corresponding to about one million solar masses. This intense activity also corresponds to the presence of areas in which the matter is rarefied, which were probably formed following a combination of stellar winds and supernovae explosions. The starburst of the galaxy is believed to have occurred around one million years ago.
Etymology
Kiso 5639 has been referred to as the Skyrocket Galaxy, an informal name due to it being described as resembling a "July 4th skyrocket" by NASA. It has also been informally called the Rocket Galaxy due to its "tail" structure and brightness at the head.
Morphology
Kiso 5639 has an extremely irregular shape. At the head is an intense concentration of stars compared to the rest of the galaxy, such that it resembles a tadpole. This area of high intensity is determined by the presence of abundant concentrations of hydrogen gas and intense star formation activity. The galaxy has an elongated and flattened "pancake" shape, with a maximum diameter that extends for approximately 2,700 light years.
Discovery
Kiso 5639 was discovered in 2004 using the Hubble Space Telescope, and was further observed in February and July of 2015 with the Wide Field Camera 3.
Star formation
Faint areas of star formation are present in other parts of the galaxy, with stellar elements ranging in age from several million to a few billion years. These data were collected from observations made by the Hubble Space Telescope during 2015 and were published in The Astrophysical Journal. The starburst is believed to have begun approximately one million years ago following the galaxy's encounter with a filament of intergalactic gas. The new stars in the galaxy are distributed in about ten groups and have a mass corresponding to about one million solar masses.
Gallery
See also
Lists of galaxies
Galaxy formation and evolution
Tadpole Galaxy
References
Further reading
External links
Skyrocket Galaxy at ESA
Skyrocket Galaxy at NASA.gov
Active galaxies
Astronomical objects discovered in 2004
Starburst galaxies
Ursa Major | Kiso 5639 | [
"Astronomy"
] | 478 | [
"Ursa Major",
"Constellations"
] |
76,652,932 | https://en.wikipedia.org/wiki/Pegulicianine | Pegulicianine, sold under the brand name Lumisight, is an optical imaging agent. It is given via intravenous injection.
Pegulicianine was approved for medical use in the United States in April 2024. The US Food and Drug Administration (FDA) considers it to be a first-in-class medication.
Medical uses
Pegulicianine is indicated for fluorescence imaging in adults with breast cancer as an adjunct for the intraoperative detection of cancerous tissue within the resection cavity following removal of the primary specimen during lumpectomy surgery.
History
The efficacy and safety of pegulicianine were evaluated in a multicenter, intra-participant controlled clinical trial (NCT03686215) of participants with breast cancer undergoing lumpectomy surgery. A total of 357 participants underwent image-guided surgery with the Lumicell DVS following standard of care lumpectomy. When positive pegulicianine signal was detected, the tissue was resected with a cavity shave procedure. The study assessed the proportion of participants receiving pegulicianine who had residual cancer detected and removed after the standard of care lumpectomy. A total of 27 of 357 participants (7.6%) had cancer in at least one pegulicianine-guided shave. The study also assessed the image-level sensitivity (ability to designate an imaged region with disease as positive) and specificity (ability to designate an imaged region without disease as negative) for detection of cancer in the lumpectomy cavity. Sensitivity was 49.1% and specificity was 86.5%. Forty-three percent (43%) of participants had at least one false positive image and 8% of participants had at least one false negative image.
The FDA granted the application for pegulicianine fast track and priority review designations.
Society and culture
Pegulicianine is the international nonproprietary name.
References
External links
Optical imaging
Sulfonamides
Peptides | Pegulicianine | [
"Chemistry"
] | 402 | [
"Biomolecules by chemical classification",
"Peptides",
"Molecular biology"
] |
76,655,780 | https://en.wikipedia.org/wiki/Angelita%20C.%20et%20al.%20v.%20California%20Department%20of%20Pesticide%20Regulation | Angelita C. et al. v. California Department of Pesticide Regulation is an administrative complaint filed in June 1999 with the US Environmental Protection Agency about disproportionate harm to Latino children from toxic pesticides used near schools. It said that the California Department of Pesticide Regulation (CDPR) had caused discriminatory harm to Latino children when it renewed the registration for methyl bromide in January 1999 without considering the effect on nearby schools, which in some cases lay immediately adjacent to the fields.
Title VI of the federal Civil Rights Act of 1964 prohibits recipients of federal funds from discriminating, even through unintended effects of neutral legislation. California has a similar law, section 11135.
Background
Strawberry cultivation is a billion-dollar industry in Central California. California supplies 90% of the nation's strawberries.
In addition to strawberries, Salinas Valley grows lettuce and has been called the salad bowl of the nation. It and the city of Monterey were the setting for some of John Steinbeck's novels. While etched into American consciousness by the photography of Dorothea Lange and John Ford's adaptation of The Grapes of Wrath starring Henry Fonda, the Dust Bowl Okies who streamed into California in the 1930s were historical anomalies. Mexicans had been migrating north to work in those fields since the 19th century.
The complaint was named "Angelita C." after the mother of a student at Ohlone Elementary School in Pajaro, where it is surrounded by strawberry fields. Another three schools were in Pajaro and Salinas in Monterey County. Another was in Santa Cruz County near Watsonville. Two were in Oxnard in Ventura County, including Rio Mesa High, attended by the son of Maria Garcia, who later appealed the settlement of Angelita C. after the subsequent recertification of methyl bromide as a pesticide as if Angelita C. had never happened.
Agriculture
Some 25 million acres of California's 101 million total make up the 77,000 farms in the state. The average farm size is well below the national average. California has the largest agricultural economy in the country by revenue, and generated more than $46 billion in 2013 on farms that are smaller than the nationwide average.
The University of California, Davis has had a strawberry breeding program since the 1930s that generated about 60% of California's strawberry plants. Two high yield varieties released in 2019, Moxie and Royal Royce, may increase strawberry yield as much as 29 percent.
California grows 90% of the strawberries produced in the United States, many of them on the Central Coast. By 2022 strawberry production for Monterey County alone had reached $958.7 million.
Farmworker families
These strawberries were almost entirely harvested by poorly paid Mixtec and Triqui workers from Oaxaca. through back-breaking stoop labor in toxic working conditions. About 75% of the farmworkers in California were undocumented in 2014 and in Santa Cruz County the percentage was 83%. An estimated 165,000 California farmworkers are indigenous Mexicans. More than half speak Mixteco and another 30 percent speak Zapoteco.
But the increase in acres in production may have been due to cheap and available land in southern Monterey County. Agricultural acreage peaked and began to shrink. Migrant farm-workers kept coming, as they have since the bracero program began in 1942, mostly from the same Mixteco villages. Most of these fieldworkers had a fifth grade education in Spanish at best, let alone English. Wage theft, crippling production quotas and predatory sharecropping arrangements and extremely toxic work environments have historically been routine. Workers share rooms with up to three other people in squalid pest-infested structures whose roofs may leak or whose plumbing may not work, Some prefer to live outdoors altogether.
A 2008 study using 2005 data by the Institute of Spatial Analysis and the California Center for Rural Policy at Humboldt State found that 593 acres of agricultural land fell within a quarter-mile of Salinas schools. But pesticide drift is not the only means of exposure, cautioned a study author: “Everyone living in that region,” is a farm-worker, and thousands of farm-workers carry the chemicals home on their clothing, or into public places. An early finding of the National Institute of Health's Agricultural Health Study was that "participants could be exposed to pesticides through living near where pesticides were mixed or stored, and laundering clothing worn during pesticide application".
The risks to farmworkers and their families specifically are in addition to the health risks to the rural population as a whole. The US Centers for Disease Control (CDC) estimates, for example, that rural populations are four times less likely to have access to healthy food. Rural communities are poorer, more elderly, and lack transportation and access to health services. They see a higher rate of excess deaths from cancer and cardiovascular disease.
Legal
Title VI of the Civil Rights Act of 1964 and its implementing regulations prohibit recipients of federal financial funding from discriminating based on race, color, or national origin, whether the disproportionate harm is intentional or simply a disproportionate effect of a neutral policy.
However, in 2001 the US Supreme Court ruled in Alexander v. Sandoval that individuals have no right to sue over the discriminatory effects of government actions, and the United States Environmental Protection Agency (EPA) itself is responsible for overseeing and investigating its own actions under Title VI regulations outlined in 40 C.F.R. Part 7. The plaintiffs filed an administrative complaint about disproportionately harmful effects on non-white schoolchildren because the California Department of Pesticide Regulation received federal funds.
Environment
Soil fumigation with chloropicrin (CP) was first introduced in the 1950s and methyl bromide (MB) in the 1960s to improve productivity. Arthropods, nematodes, weeds, fungi and pathogens like Verticillium dahliae, Fusarium oxysporum, and Macrophomina phaseolina can destroy a harvest. Early on, CP and MB were mixed together to allow strawberries to be produced as an annual rather than biennial crop without crop rotation. Fumigants also led to higher and more predictable yields and fruit quality. Strawberry yields statewide ranged from two to four tons an acre before fumigants and reached 16 tons an acre by 1969.
The Montreal Protocol, an international environmental agreement first signed in 1987 in an effort to reduce damage to the ozone layer, included methyl bromine among the chemicals to be phased out because it breaks down in the atmosphere, especially in sunlight, and releases destructive bromine radicals that can take up to two years to break down completely. In 2012 California growers were still using 3.8 million pounds of methyl bromide on 30,000 treated acres, compared to 6.5 million pounds on 53,000 treated acres in 2002, through waivers granted by the EPA.
Complaint
Filed by the Center for Race, Poverty & the Environment, California Rural Legal Assistance and the Farmworker Justice Fund, Inc. on behalf of Latino parents and children at six California schools, complaint 16R-99-R9 said that the CDPR renewal of the registration of methyl bromide caused disproportionate health harm to Latino school children due to their over-representation in schools near the fields where the pesticide was used.
Research by the complainants found that all schools near the release of methyl bromide had a student population that was majority non-white. The student populations of Virginia Rocca Barton Elementary School in Salinas and Ohlone Elementary School both were more than 95% ethnic. In 1995 complainants found that a total of 75,000 pounds of methyl bromide was released within a 1.5 mile radius of 476 students. Notably, the spraying occurred from mid-August through late May, while school was in session.
Investigation
To calculate whether or not spraying methyl bromide had an adverse effect on children in the vicinity, the OCR used data from 1995 to 2001 in the CDPR's previously developed model. and found that both short-term and long-term exposure levels exceeded the EPA's threshold of concern (35 ppb and 1.3 ppb, respectively). It also found merit to the claim of a disproportionate adverse effect on Latino schoolchildren between 1995 and 2001. This was, it said, enough evidence of a prima facie violation of Title VI. This was the EPA's first ever and to date only finding of a prima facie violation.
Many limitations of the EPA investigation impaired its outcome. An open letter to the OCR signed by a long list of advocates in response to a 2016 proposal to loosen its accountability requirements scathingly noted among many other enforcement failures that the agency had taken "nearly twelve years" to respond to Angelita C., which by the EPA's own standards should have had preliminary findings within 180 days. "While the complaint languished, Latino schoolchildren were exposed on a daily basis to toxic pesticides," they said. Even then, another author angrily wrote, the EPA essentially "told the CDPR 'Just try to help people stay out of the way.'" The EPA excluded complainants from the investigation, and did not notify the plaintiffs of its finding of discrimination until it announced the settlement agreement, without giving any relief to Latino schoolchildren from pesticide exposure during mandatory school attendance.
In 2011 when the settlement was reached, the EPA planned to replace methyl bromide with methyl iodide, which breaks down within 12 days and does not deplete the ozone layer. A plaintiffs' attorney in the methyl bromide complaint said:
As a "carcinogen, neurotoxin, and endocrine disruptor" the adverse health effects of methyl iodide on farmworkers and others in the vicinity of its use turned out to be if anything worse than methyl bromide's, and its manufacturer withdrew it from the US market ahead of a decision in litigation brought by Earthjustice.
Regulation
California Department of Pesticide Regulation
"Ongoing, systematic and widespread violations of the civil rights of residents and workers in California's farmworking communities, both through actively discriminatory policies that cause disproportionate harm, but more pervasively through failure to investigate, to protect and to enforce existing state laws and regulations,” have occurred, according to Jane Sellen of the Environmental Health Sciences Center of the University of California at Davis.
A lawsuit filed March 29, 2024 in Monterey Superior Court against the California DPR and the Monterey County Agricultural Commissioner by Earthjustice on behalf of the Pajaro Valley Federation of Teachers, Safe Ag Safe Schools, Center for Farmworker Families, Monterey Bay Central Labor Council and Californians for Pesticide Reform alleged that students at three schools in the Pajaro Valley—including one named in the original Angelita C. complaint—are exposed to more than twice the levels of 1,3-dichloropropene (1,3-D) that the CDR has said was the maximum safe dose, yet the DPR continues to routinely approve applications for further use of the chemical.
EPA
Methyl iodide was approved for use in the United States despite its health risks, after EPA director Stephen Johnson appointed as a regulator Elin Miller, previously the CEO of the North American branch of Arysta, the Japanese manufacturer of methyl iodide. The eminent science journal Nature accused Johnson, a George W. Bush appointee, of "reckless disregard for law, science or the agency's own rules — or, it seems, the anguished protests of his own subordinates." After the approval of methyl iodide's registration as a pesticide available in the United States, Arysta sold for $2.2 billion.
Fifty-four scientists signed a letter of protest to the EPA strongly recommending against its approval, citing omissions of peer-reviewed evidence, failure to document the modeling used, missing information and failure to identify vulnerable subpopulations. The agency's assessment of risk to nearby populations also incorrectly treated exposure as "missing" and it should have used the AERMOD model instead. Estimates of risk due to the length of the workday; "exposure during tarp removal is completely uncharacterized," they said, and "air filtering respirators are inappropriately relied on and respiratory protection factors are overestimated."
"We have had the administrator come in and, in my opinion, lie to this committee." fumed Senator Sheldon Whitehouse of Rhode Island at a 2008 hearing of the United States Senate Committee on Environment and Public Works. "This looks like an agency that is now captive in the hands of industry, and is led by people whose job is not to follow the science, is not to protect the public, but is to deliver for the industry and then say whatever nonsense is necessary to try to cover their tracks."
A 2015 review by the Center for Public Integrity of 265 complaints submitted to the civil-rights office found that "settlements are rare, investigations often cursory and findings of discrimination all but non-existent." Dismissal of complaints by the EPA was the outcome 90% of the time. Documents obtained by the CRPE, representing the plaintiffs, showed that the Office of Pesticide Programs objected to measures suggested by the Office of Civil Rights, such as impermeable films and buffer zones, as it felt that these measures implied that the long-term exposure thresholds established by the EPA had been inadequate. The agency has only ever pulled the registration for 37 pesticides, four of them between 2000 and 2010, and only one since. It has registered more than 16,800 pesticide products and 1,200 active ingredients.
EPA managers at a November 18, 2020 meeting asked the information technology contractors building a tracking system for chemical reviews to add a new button to the interface to allow them to bypass the scientists and send high-priority cases straight to management for approval.
Reporting by The Intercept in 2021 found that pesticide manufacturers frequently hired agency employees and "more than two dozen experts on pesticide regulation — including 14 who worked at the EPA's Office of Pesticide Programs" said the industry spends tens of millions of dollars on lobbying agency employees. Agency whistleblowers described physical intimidation and abusive language, and managers were evaluated on the number of chemicals they approved and whistleblowers reported hearing them advise manufacturer representatives on cellphones to avoid creating public records. "An assessment of 1,3-D that the Environmental Protection Agency issued in 2020 is fraudulent", according to a complaint the environmental group Public Employees for Environmental Responsibility (PEER) submitted to the EPA's Office of Inspector General in February 2021. "If you do decide to work for the [EPA] pesticide program and you go up against the agricultural interest, it will not be good for your career,” former EPA employee Karen McCormack, a veteran of forty years with the agency, told Al-Jazeera in December 2023.
United States Congress
Changes in mmigration law have greatly altered the landscape for migrant workers. Quoting Rudolf Virchow's observation that “Medicine is a social science, and politics is nothing else but medicine on a large scale” Seth M. Holmes noted in his study of migrant farmworker health that "the nexus of political economic structures driving migration with legal structures barring entry to immigrants and widespread anti-immigrant sentiments proves unhealthy and dangerous." Political developments have made life harder for these workers, from bills to give local police the authority to investigate and enforce federal immigration laws, new fences and increased militarization of the US-Mexico border to the George W. Bush proposal of a "poorly defined temporary worker program that appears to make the power differential between worker and employer even greater than it is already."
Pressure on EPA regulators often came from lawmakers. At a 2006 hearing of the House Committee on Agriculture's Subcommittee on Conservation, Credit, Rural Development, and Research, EPA Assistant Administrator James B Gulliford of the Pesticides and Toxic Substances branch was aggressively questioned by Congressman Bob Etheridge of North Carolina about methyl bromide and critical use exemptions. Joe Schwarz of Michigan wanted to know "...why we are not doing more to perhaps try to extricate at least partially from our obligations under the Montreal so that agriculture can use methyl bromide in greater volumes than it is now." He added that methyl bromide "was introduced over 70 years ago and there is no real evidence that there is any kind of a health hazard for humans or there is any runoff because of the gas."
Aftermath
After the EPA issued a preliminary finding against the CDPR on April 22, 2011, it began private settlement discussions with the defendant, to which the complainants were not invited. On August 24, 2011, the EPA and CDPR reached an informal compliance agreement. An appeal of this administrative decision was denied. In 2014 the strawberry growers of California still accounted for roughly 90% of the methyl bromide use in the developed world.
In Garcia v. McCarthy the plaintiffs appealed to first to the District Court for Northern California, then to the US 9th Circuit Court of Appeals, saying that the settlement did not provide recourse to those exposed; the CDPR made no changes to the pesticide's registration in 2013 and re-registered and lawfully certified it as of January 26, 2012, despite its own finding of discriminatory harm. The plaintiffs said that the EPA failed to investigate health effects and “arbitrarily and capriciously” negotiated a voluntary compliance agreement that did not protect schoolchildren and that plaintiffs were excluded from the investigation and the settlement negotiations. The court granted a motion to dismiss, saying that despite the "lamentable" delay the agency was empowered to settle the matter as it saw fit.
An April 2014 report by California's Environmental Health Tracking Program found that Hispanic children were more likely to attend schools near the fields and farms that used the most pesticides of public health concern: 46% more likely than White children to attend schools where any pesticides of concern were used nearby, and 91% more likely than White children to attend schools that w ere in the highest quartile of nearby use.
The director of the California Department of Pesticide Regulation noted in an editorial published in the Sacramento Bee in 2015 that "because land use is a local affair, school locations are exempt from the General Plan and other measures designed to ensure thoughtful planning. As a result, schools are sometimes built on prime agricultural land in the middle of existing farm operations." He said he had directed his staff to draft new regulations and that the depaatment would hold a series of hearings on the subject. When the revised rules were published, they only prohibited pesticide application from 6 a.m. to 6 p.m. on weekdays, within a quarter mile of the schools. A spokesperson confirmed that grower pushback in the public comment period had led the department to drop a requirement to give 48 hours notice before spraying.
in 2018, California counties with a majority Latino population used more than 900% more pesticides per square mile than those with less than 25% Latino populations.
Health risks
All of the alternatives to methyl bromide also pose health risks. A mixture has been considered a likely alternative, but the low solubility of the chemicals means a risk of groundwater contamination.
Methyl bromide
Methyl bromide is a neurotoxin.
Accidental poisonings with methyl bromide have been recorded, but few cases documented the concentrations or duration of exposure. It is practically odorless, even at lethal doses, and can cause headaches, mental disturbances, nausea, vomiting and lung edema. According to the National Research Council, "Daily exposure to methyl bromide at 35 ppm (with possible dermal contact) and acute exposures to several hundred ppm can cause mild to severe symptoms".
1,3-Dichloropropene
The US National Institute for Occupational Safety and Health (NIOSH) considers 1,3-Dichloropropene (1,3-D), sold under the brand name Telone, a carcinogen. Telone was also for years contaminated with 1,2,3-trichloropropane (TCP), another extremely potent carcinogen that persists for centuries, even though the label claimed it had no inert ingredients for the "sales advantage", according to filings in some of the ensuing litigation. The pesticide also causes respiratory problems.
During the Trump administration the federal EPA downgraded the assessed cancer risk of 1,3-D. The inspector-general of the EPA said the move "could lead to significant increases in exposure levels to humans and affect the pesticide's application rate and level of personal protective equipment required by applicators. The EPA needs to take action to improve the scientific credibility of and bolster public trust in the Agency's 1,3-D decision." The Pajaro Valley environmental group Safe Ag/Safe Schools in 2022 called for an increasing the quarter-mile buffer zone around schools, noting that a school in Shafter in Kern County had recorded one of the highest 1,3-D levels ever from an application of 1,3-D in a field 7.5 miles away.
California's Office of Environmental Health Hazard Assessment (OEHHA) set a maximum safe exposure level of 0.04 parts per billion in June 2023. Draft regulations DPR published in November 2023 set the level to 0.56 ppb, 14 times higher than its own employees had said was the maximum safe dose.
Chloropicrin
US EPA re-approved chloropicrin (PS) in 2008 as safe for use in agricultural settings, stating that treatments "can provide benefits to both food consumers and growers. For consumers, it means more fresh fruits and vegetables can be cheaply produced domestically year-round because several severe pest problems can be efficiently controlled." The EPA requires supervision, training and certification of applicators, buffer zones, notice of pesticide application, and fumigant management plans. The US National Institute for Occupational Safety and Health considers it a lung-damaging agent and warns that it may explode.
See also
1986 California Proposition 65
Administrative Procedure Act
California Agricultural Labor Relations Act of 1975
California Environmental Quality Act
Federal Insecticide, Fungicide, and Rodenticide Act
Food Quality Protection Act
Heckler v. Chaney
Migrant and Seasonal Agricultural Workers Protection Act of 1983
Plasticulture
Salad Bowl strike
United Farm Workers
Notes
References
Citations
Bibliography
Further reading
Budnik, L.T., Kloth, S., Velasco-Garrido, M. et al. Prostate cancer and toxicity from critical use exemptions of methyl bromide: Environmental protection helps protect against human health risks. Environ Health 11, 5 (2012). https://doi.org/10.1186/1476-069X-11-5
Cone, Marla, EPA Drops Plan to Approve Pesticide, Los Angeles Times 27 April 2006
De Witte, Melissa; Pesticide predicament for California's strawberry growers: UC Santa Cruz's Julie Guthman examines industry's challenges as heavily used methyl bromide is phased out; NEWSCENTER, University of California, Santa Cruz. 28 September 2016
Environmental Working Group, Study: Communities of color at greatest risk of pesticide exposure in Ventura County, California, Phys.org, September 15, 2022
Gross, Liz; Fields of Toxic Pesticides Surround the Schools of Ventura County, Food & Environment Reporting Network, 6 April 2015
Herdt, Timm, Critic calls methyl iodide unsafe for use in the state, Ventura County Star, 30 April 2010
Hermouet C et al. Methyl iodide poisoning: report of two cases Am J Ind Med . 1996 Dec;30(6):759-64. doi: 10.1002/(SICI)1097-0274(199612)30:6<759::AID-AJIM13>3.0.CO;2-1. PMID 8914723
Holden, Lindsay and Miranda, Mathew; California has a housing crisis. Why are thousands of farmworker apartments closed each year? 28 March 2024
Holmes, Gerald J. Mansouripour, Seyed Mojtaba and Hewavitharana Shashika S; Strawberries at the Crossroads: Management of Soilborne Diseases in California Without Methyl Bromide Phytopathology 6 Apr 2020 https://doi.org/10.1094/PHYTO-11-19-0406-IA
Hoops, Stephanie, Oxnard nursery was the test site for controversial pesticide: State to decide if methyl iodide OK. Ventura County Star, 30 October 2007
Howe, Kevin, Judge to Hear Methyl Iodid Arguments: Groups Say Chemical Used on Strawberries Is Too Harsh, Santa Cruz Sentinel, 11 January 2012
Jones, N. Scientists fume over California's pesticide plans. Nature (2010). https://doi.org/10.1038/news.2010.218
KCAL News, Ventura County Rescinds Permit For Controversial Fumigant, 15 April 2011
Amy Littlefield; Bettina Boxall; Debate over fumigant heats up Assembly labor panel, Los Angeles Times, 21 August 2009
Nair, J.R., Chatterjee, K. Methyl iodide poisoning presenting as a mimic of acute stroke: a case report. J Med Case Reports 4, 177 (2010). https://doi.org/10.1186/1752-1947-4-177
Orozco-Ramírez, Q., Bocco, G., & Solís-Castillo, B. (2020). Cajete maize in the Mixteca Alta region of Oaxaca, Mexico: adaptation, transformation, and permanence. Agroecology and Sustainable Food Systems, 44(9), 1162–1184. https://doi.org/10.1080/21683565.2019.1646374
Sanchez, M.G., 2020. Understanding Environmental Injustice in Toxic Pesticide Exposure along the California's Agricultural Central Coast. University of California, Davis.
Sanchez, Zaydee; California's new pesticide notification system aims to protect public health. Will it work?: Community activists were instrumental in achieving the landmark program. But they worry it won't go far enough to shield rural communities and farmworkers from pesticide harm., Envisonmental Health Network, 10 February 2023
Splinks, Rosie; Refusing to Bend: The children of Central California farmworkers have launched a ground-level battle against agribusiness, Sierra, July 25, 2011
Walters, M., 2021. The Systematic Exclusion of Complainants and Impacted Communities in EPA External Civil Rights Compliance Office's Title VI Resolution Process: Recommendations for ECRCO and States. Geo. Env't L. Rev., 34, p. 527.
Weimerskirch, Peter J, Burkhart, Keith K, Bono, Michael J, Finch, Albert B, Montes, Jorge E; Methylene iodide poisoning: CASE REPORT. Volume 19, Issue 10, P1171-1176, October 1990. DOI:https://doi.org/10.1016/S0196-0644(05)81524-0
GOSIA WOZNIACKA, Associated Press; Neighbors oppose strawberry farms’ fumigant use San Diego Union-Tribune, 13 May 2011
External links
40 C.F.R. § 7.115, Cornell Law School
Californian Institute for Rural Studies, FARMWORKER HOUSING STUDY AND ACTION PLAN FOR SALINAS VALLEY AND PAJARO VALLEY, June 2018
California Code Section 11135. FindLaw
International Agency for Research on Cancer, IARC Working Group on the Evaluation of Carcinogenic Risks to Humans. Re-evaluation of Some Organic Chemicals, Hydrazine and Hydrogen Peroxide. Lyon (FR): 1999. (IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, No. 71.) Methyl iodide. Available from: https://www.ncbi.nlm.nih.gov/books/NBK498987/
Garcia v. McCarthy, Case No. 13-cv-03939-WHO (N.D. Cal. Jan. 16, 2014)
PUBLIC LAW 110–94—OCT. 9, 2007 PESTICIDE REGISTRATION IMPROVEMENT RENEWAL ACT Federal Insecticide, Fungicide, and Rodenticide Act
Title VI, Civil Rights Act of 1964
Pesticide regulation in the United States
Strawberry production
Farmworkers
Environmental toxicology
United States environmental case law | Angelita C. et al. v. California Department of Pesticide Regulation | [
"Environmental_science"
] | 5,925 | [
"Toxicology",
"Environmental toxicology"
] |
76,655,829 | https://en.wikipedia.org/wiki/PGC%2029820 | PGC 29820 (known as JO204) is a spiral galaxy 600 million light-years from the Solar System, in the Sextans constellation. The galaxy is about 120,000 light-years in diameter and is a member of Abell 957, a low-mass galaxy cluster. The first known reference to this galaxy is from volume I of the Catalogue of Galaxies and of Clusters of Galaxies compiled by Fritz Zwicky in 1961, where it was listed as CGCG 008-077.
Characteristics
PGC 29820 is classified a massive galaxy with a stellar mass of M* = 4 x1010 M. It contains an active galactic nucleus with double-peaked narrow lines. Moreover, it is also a Seyfert 2 galaxy.
PGC 29820 is classified a jellyfish galaxy. According to Gullieuszik, the galaxy is currently in a first phrase of infalling into the cluster where it is subjected to ram pressure by the intracluster medium.
Because dense gas is compressed, it eventually collapses to form new stars in both the galaxy's tail and its disk. According to researchers, the stars inside the tail, has a star formation rate of 0.22 M○ yr1 which began during the last 500 million years.
In additional, PGC 29820 shows a large presence of molecular gas making up H2 mass of 8.3 x 109 M○. Looking at ratio of total molecular hydrogen mass and stellar mass, it is estimated as 0.42.
See also
IC 4141
PGC 65543
PGC 1228197
ESO 137-001
References
029820
Sextans
Spiral galaxies
Seyfert galaxies
029820 | PGC 29820 | [
"Astronomy"
] | 349 | [
"Sextans",
"Constellations"
] |
76,655,971 | https://en.wikipedia.org/wiki/PGC%2065543 | PGC 65543 ( known as JO175), is a spiral galaxy, with extensive star forming regions, located in Indus. It is 650 million light-years away from the Solar System and approximately measuring 90,000 light-years in diameter. The tidal interactions from certain galaxies which PGC 65543 is moving towards to, have caused it to get distorted. Its star-forming gas and dust are dynamically stripped by ram-pressure and formed into tendrils that stretch outwards, thus gives an appearance of a jellyfish galaxy.
See also
PGC 29820
IC 4141
References
Indus (constellation)
Spiral galaxies
65543 | PGC 65543 | [
"Astronomy"
] | 133 | [
"Indus (constellation)",
"Constellations"
] |
76,656,159 | https://en.wikipedia.org/wiki/PGC%201228197 | PGC 1228197 known as WINGS J211347.41+022834.9 and JO206, is a large spiral galaxy located 700 million light-years away towards the constellation of Aquarius. The galaxy is estimated to be at least 160,000 light-years in diameter, making it somehow bigger than the Milky Way. With a radial velocity of 15,226 kilometers per second, it is slowly drifting away.
PGC 1228197 is a member of a poor galaxy cluster called II ZW 108. It has a stellar mass of 8.5 × 1010 M○.
PGC 1228197 is classified as a jellyfish galaxy. It has a lengthy tail that is ≥90 kpc wide, with ionized gas stripped from the galaxy. The galaxy is surrounded by its own magnetized intracluster medium drape.
Such process is caused when it interacts with other galaxies causing it to run into intracluster medium. The galaxy then undergoes a process of ram-pressure where its gas is stripped, forming long galactic tendrils of stars. Because matter is accreted into its supermassive black hole, its active galactic nucleus is trigged.
See also
IC 4141
PGC 29820
PGC 65543
ESO 137-001
References
Aquarius (constellation)
Spiral galaxies
Principal Galaxies Catalogue objects
LEDA objects
J21134738+0228347 | PGC 1228197 | [
"Astronomy"
] | 291 | [
"Constellations",
"Aquarius (constellation)"
] |
76,656,706 | https://en.wikipedia.org/wiki/Jong-Soo%20Rhyee | Jong-Soo Rhyee is a South Korean physicist and materials scientist. He is a professor in the Department of Applied Physics at the Applied Science College of Kyung Hee University and serves as the Outside Director at KPT, the Representative CEO of V-memory, and the CTO of R-Materials in South Korea.
Rhyee's research spans across domains of material science, encompassing magnetic and energy materials, crystal growth, thermoelectric materials, high thermal conductivity materials, magneto-caloric effect materials, unconventional properties of oxides and intermetallics, and superconductivity. He is the recipient of the 2009 Young Investigator Award by the International Thermoelectric Society and the 2018 IAAM Scientist Medal by the International Association of Advanced Materials.
Rhyee holds 19 Korean patents along with 32 international patents.
Education and early career
Rhyee obtained his Bachelor's in Physics from Chung-buk National University in 1998, and a Master's in Experimental Solid-State Physics from Pohang University of Science and Technology (POSTECH) in 2000 under advisor Sung Ik Lee. He pursued a Ph.D. in Magnetic Materials at Gwangju Institute of Science and Technology (GIST) from 2000 to 2005, researching Hexaboride compounds under advisor Beong Ki Cho.
Career
Rhyee worked as a Postdoc Researcher in the Crystal Growth group at Max Planck Institute for Solid State Research in Germany from April 2006 to April 2007 and then served as an R&D Staff Researcher at the Materials Research Lab at Samsung Advanced Institute of Technology (SAIT) from May 2007 to August 2010. He moved into academia as an assistant professor at the Department of Applied Physics of the Applied Science College at Kyung Hee University in South Korea in 2010, becoming associate professor in 2014 and Professor in 2019
While in the role of associate professor, Rhyee concurrently held the position of department chair for the Department of Applied Physics from March 2017 to February 2019, and as the Vice Dean of the Applied Science College at Kyung Hee University from March 2018 to February 2019. He has been serving as the Outside Director at KPT since June 2022, as well as the CTO at R-Materials in South Korea since January 2023, and has also been acting as the Representative CEO of V-memory in South Korea since January 2020.
Research
Rhyee's research has focused on developing new materials in fields such as magnetic, superconductivity, and energy materials. He has investigated crystal growth in intermetallic and oxide compounds, studied thermoelectric materials for waste heat recovery and high thermal conductive materials for electronic applications. Additionally, his research has encompassed magneto-caloric effect materials for solid-state cooling, unconventional properties of oxides and intermetallics, and quasi-one-dimensional electronic transport. He has also explored soft magnetic materials, topological and Weyl semimetallic system, and superconductivity.
Magnetism and thermoelectric research
During his time at SAIT's Materials Research Center, Rhyee developed high-performance thermoelectric materials In4Se3−δ, published in Nature on 2009. This research proposed an approach to enhance ZT thermoelectric materials through Peierls distortion. He provided both experimental evidence and theoretical insights demonstrating that alloying SnTe with Ca significantly improved its transport properties, leading to a ZT of 1.35 at 873 K, the highest reported ZT value for singly doped SnTe materials. The study predicted approximately 10% efficiency for high-temperature thermoelectric power generation using SnTe-based materials, assuming a 400 K temperature difference. Furthermore, his work enhanced the thermoelectric properties of In4Se3–xCl0.03 bulk crystals through Ca alloying, and showed that intercalation of Cu nanoparticles between Te layers in Bi2Te3 transforms its native p-type character to n-type, reducing thermal conductivity and enhancing thermoelectric performance with a figure of merit (ZT) of 1.15 at approximately 300 K. His research also addressed the development of high-mobility transistors using CVD-grown MoSe2 films for applications like high-resolution displays.
Within his magnetism and thermoelectric research, Rhyee has explored unconventional magnetism in boride and intermetallic compounds, with a focus on magnetic polaronic transport and correlated properties. He examined the link between topological states and thermoelectricity, discovering that the topological phase transition in Dirac semimetals boosts thermoelectric performance. Further investigations revealed that selective charge Anderson localization is a novel avenue for enhancing thermoelectricity, yielding a ZT value of 2.0 in n-type thermoelectric power generation. In a collaborative work, he presented a novel magnetic field-induced type II Weyl semimetallic state in the Shastry-Sutherland lattice, characterized by non-trivial Berry phase, magnetic field-induced Weyl nodes and spin chirality, chiral anomaly, anomalous magnetoconductivity, and demonstrated topological phase evolution.
Awards and honors
2009 – Young Investigator Award, by International Thermoelectric Society
2018 – IAAM Scientist Medal, International Association of Advanced Materials
Selected articles
Rhyee, J. S., Lee, K. H., Lee, S. M., Cho, E., Kim, S. I., Lee, E., ... & Kotliar, G. (2009). Peierls distortion as a route to high thermoelectric performance in In4Se3-δ crystals. Nature, 459(7249), 965–968.
Rhyee, J. S., Ahn, K., Lee, K. H., Ji, H. S., & Shim, J. H. (2011). Enhancement of the Thermoelectric Figure‐of‐Merit in a Wide Temperature Range in In4Se3–xCl0. 03 Bulk Crystals. Advanced Materials, 23(19), 2191–2194.
Han, M. K., Ahn, K., Kim, H., Rhyee, J. S., & Kim, S. J. (2011). Formation of Cu nanoparticles in layered Bi 2 Te 3 and their effect on ZT enhancement. Journal of Materials Chemistry, 21(30), 11365–11370.
Al Rahal Al Orabi, R., Mecholsky, N. A., Hwang, J., Kim, W., Rhyee, J. S., Wee, D., & Fornari, M. (2016). Band degeneracy, low thermal conductivity, and high thermoelectric figure of merit in SnTe–CaTe alloys. Chemistry of Materials, 28(1), 376–384.
Rhyee, J. S., Kwon, J., Dak, P., Kim, J. H., Kim, S. M., Park, J., ... & Kim, S. (2016). High‐mobility transistors based on large‐area and highly crystalline CVD‐grown MoSe2 films on insulating substrates. Advanced Materials, 28(12), 2316–2321.
References
South Korean physicists
South Korean scientists
Materials scientists and engineers
Chungbuk National University alumni
Pohang University of Science and Technology alumni
Gwangju University alumni
Academic staff of Kyung Hee University
Year of birth missing (living people)
Living people | Jong-Soo Rhyee | [
"Materials_science",
"Engineering"
] | 1,603 | [
"Materials scientists and engineers",
"Materials science"
] |
76,656,899 | https://en.wikipedia.org/wiki/Arp%20146 | Arp 146 (known as PGC 509 and PGC 510) are a pair of interacting galaxies located 1.05 billion light-years away from Earth in the Cetus constellation. It was discovered by Dewhirst and catalogued by Boris Vorontsov-Velyaminov as VV 790. Under the Atlas of Peculiar Galaxies created by Halton Arp, they are categorized under galaxies that have associated rings.
Arp 146 is classfied as an example of an empty ring galaxy. According to a study, one galaxy appears to have passed through another, leaving behind a ring formed from the bridge material and remnants of the nucleus. The ring is said to be 18"x11" elliptical measuring 20 kpc in diameter but separated from its companion.
References
Ring galaxies
Interacting galaxies
Cetus
146
00509 | Arp 146 | [
"Astronomy"
] | 169 | [
"Galaxy stubs",
"Astronomy stubs",
"Constellations",
"Cetus"
] |
76,659,837 | https://en.wikipedia.org/wiki/UNCOVER-z13 | UNCOVER-z13 is a high-redshift Lyman-break galaxy discovered by the James Webb Space Telescope (JWST) during NIRCam imaging for the JWST Ultradeep NIRSpec and NIRCam Observations before the Epoch of Reionization (UNCOVER) project on November 14, 2023. UNCOVER-z13 is within Abell 2744 supercluster in the constellation Sculptor.
Morphology
UNCOVER-z13 is a Lyman-Break galaxy, and not much more is known about the exact shape of the galaxy.
Discovery
UNCOVER-z13 was first observed when large amounts of gravitational lensing from Abell 2744 made the galaxy visible. Abell 2744 is around 3.5 billion light-years away from the Milky Way. The gravity of Abell 2744 warps the fabric of space-time sufficiently to magnify the light of more faraway galaxies. The James Webb Space Telescope used the gravitational lensing to discover UNCOVER-z13.
UNCOVER-z12
UNCOVER-z12 is a second galaxy which was discovered around the same time. UNCOVER-z12 has a redshift of 12.393, making it the fourth-most distant object ever observed. It is a Lyman-Break galaxy, and was discovered using the same methods as UNCOVER-z13.
Gallery
See also
List of the most distant astronomical objects
JADES-GS-z14-0, furthest galaxy ever recorded
JADES-GS-z13-0, former furthest galaxy ever recorded
References
External links
UNCOVER-z13 at the JWST Feed
UNCOVER-z13 at IOPScience.org
Astronomical objects discovered in 2023
Galaxies
Discoveries by the James Webb Space Telescope
Galaxies discovered in 2023
Sculptor (constellation) | UNCOVER-z13 | [
"Astronomy"
] | 358 | [
"Constellations",
"Sculptor (constellation)"
] |
76,666,752 | https://en.wikipedia.org/wiki/Trichosporon%20asahii | Trichosporon asahii is a non-Candida yeast that has been reported to cause infections in immunocompromised patients. T. asahii is the most prominent human pathogen in its genus, causing more than half of all Trichosporon infections. First discovered and named in 1929, The currently accepted nomenclature of T. asahii was validated in 1994.
Disease
The clinical manifestations of T. asahii infection are non-specific and vary depending on the site of infection. The most common types of infection were urinary tract infections, fungemia, and disseminated infection. Cutaneous infections have also been reported.
Identification and culture
T. asahii grows readily on routine laboratory media, producing white, yellow, or cream, yeast-like colonies on Sabouraud dextrose agar. This fungus has a rapid growth rate and colonies mature in 5 days. When grown on cornmeal-Tween 80 agar, true hyphae, pseudohyphae, and blastoconidia can be seen under microscopic examination. Arthroconidia can be observed in older cultures. This fungus is able to hydrolyze urea through the production of urease.
Treatment
ESCMID/ECMM guidelines recommend the use of voriconazole for the treatment of invasive T. asahii infections. Patients have also been treated with amphotericin B and triazole therapy.
References
Tremellomycetes
Yeasts | Trichosporon asahii | [
"Biology"
] | 304 | [
"Yeasts",
"Fungi"
] |
76,668,625 | https://en.wikipedia.org/wiki/Navizence | The Navizence is a 23-kilometer-long Swiss river located in the Anniviers Valley, in the canton of Valais. It is a left-bank tributary of the Rhône River, joining it at Chippis.
The river originates from the Zinal Glacier and flows northward and then north-northwest. It passes through several streams, particularly from Vissoie, where its bed lies at the bottom of a crevasse. Its main tributary is the Gougra.
The water from the Navizence is utilized by multiple hydroelectric plants and can be pumped to the Moiry Dam via a system of galleries. The Navizence has encountered major floods in 1834 and 2018, resulting in extensive destruction in the Anniviers Valley and Chippis. The river is home to various benthic macroinvertebrates and brown trout.
Hydronymy
In 1267, the river was referred to as aquam de la Navisenchy. Its name could have originated from an early "Anniviers" form, with the suffix -entia, forming Anavisentia. Another possibility is that the name derives from the Gaulish "nava," which means "deep valley, ravine" in Latin, with the suffix -ence. Philologist Paul Aebischer suggests a Gaulish root anavo-, conveying ideas of inspiration and wealth.
The river has multiple spellings: "Navizance", "Navizence", "Navisance", or "Navisence". Its German name is Uzenz. In the local Arpitan dialect, it is referred to as Navijèïngtse.
Geography
Location
The Navizence flows through three municipalities in the canton of Valais: Anniviers, Chalais, and Chippis. The drainage basins of the Rèche surround it to the northwest, the Borgne to the west, the Viège from Zermatt to the south and southeast, the Turtmänna to the east, the Illgraben to the northeast, and the Rhône to the north.
Courses
The Navizence originates at 2,100 meters, at the exit of the Zinal Glacier, at the bottom of the western branch of the Anniviers Valley. At this point, the river also collects water from other glaciers, such as the Moming Glacier and the Lée Glacier. It then flows through a narrow gorge about 600 meters long. At its exit, it passes through the Plat de la Lée where several small streams join it from the Roc de la Vache, the Tracuit Glacier, Les Diablons, or the Garde de Bordon. The Navizence then flows through the village of Zinal.
About 2 km after Zinal, in Mottec, the watercourse descends sharply into a new stream with a direct and consistent slope. At this point, the river changes its direction from northward to north-northwest. Along its right bank, it is fed by water from the small Diablons Glacier, and further downstream in Ayer, it receives water from the Forcletta Pass. At an elevation of 1,287 meters above sea level, the river merges with its main tributary, the Gougra, which carries water from the Moiry Glacier and the Zozanne, Lona, and Marais lakes.
Considerably swollen by the Gougra, the Navizence flows northward and then turns north-northwest after Saint-Jean. It merges with the Moulins stream at Vissoie, which originates from the snowfields of Pointe de Nava, Toûno, and Bella Tola. As the valley narrows from Vissoie, the Navizence disappears into a canyon, receiving water from two tributaries: one from the Orzival Valley under Pinsec and the other from Schwarzhorn at Fang.
At the site known as "des Balmes," the rocky spur of Pontis, located at the base of Illhorn, alters the river course once more, this time flowing northwestward. The Navizence, reaching an elevation of 535 meters east of Chippis, spans a distance of 23 km before merging with the Rhône.
Hydrology
The Navizence basin covers an area of 255.5 km2, with the Zinal valley accounting for 114.7 km2 and the Gougra basin covering 57.1 km2. The watershed altitude ranges from 447 to 516 m, with an average altitude of 2,387 m. The surface composition of the watershed includes 27% rocks, 24% herbaceous vegetation, 21% forests (20% conifers and 1% mixed forests), 13% glaciers, and 9% loose rocks. The remaining area is divided among shrubby vegetation (3%), wetlands (2%), watercourses (1%), and urban areas (1%).
From 1981 to 2010, the average annual rainfall in the watershed was 1,020 mm/year, with precipitation increasing with altitude. May receives the highest precipitation, averaging 125 mm, and has the highest snow water equivalent at 310 mm.
The Navizence has different river regimes. It has a glacial regime from the Zinal Glacier to its confluence with the Gougra. From that point until it meets the Rhône, it is a snow-fed regime. The Strahler number of the Navizence is 5 until Vissoie, where the addition of the Moulins stream increases it to 6.
Two flow measurement discharges were established on the Navizence. The first station was located 250 m downstream of the Gougra mouth and operated from September 1928 to June 1935. The second station was situated 450 m downstream of the Vissoie road bridge and operated from January 1956 to December 1962. The average flow recorded during this period was 7.82 m3/s, with the lowest daily average of 0.89 m3/s recorded in 1959. From 1961 to 1980, the average annual flow of the Navizence was 6.19 m3/s at Vissoie and 7.21 m3/s at Chippis.
Weather
Developments
The major developments along the Navizence are located from the Chippis mill to its confluence with the Rhône. In this section, the river has been straightened with rock blocks on the left bank and a stone wall on the right bank. The remaining part of the river has been preserved in its natural state, except for stabilizations around Mottec and near certain structures.
Two compensation basins are situated along the Navizence, at Mottec and Vissoie. The first basin is utilized to regulate the flow towards Vissoie during the summer and can also pump water towards the Moiry Dam during off-peak hours. The Vissoie basin is designed to supply water to the Vissoie-Chippis open-flowing gallery.
Fauna
In samplings conducted in the 1980s, 32 taxa of benthic macroinvertebrates were recorded in the Navizence. These taxa mainly consist of insect larvae, including species of Tricladida, one of Hydrachnidia, and two of Oligochaeta. Phyla involved are Platyhelminthes (Crenobia alpina), Annelida (Lumbricidae and Tubificidae), and arthropods from the orders Ephemeroptera, Plecoptera, Coleoptera, Trichoptera, and Diptera.
The rapids at the entrance of the Anniviers Valley pose a challenge for fish migration. In the 1930s, brown trout (Salmo trutta fario) populations were introduced by catching them in the Rhône Valley and releasing them in various locations in the Anniviers Valley. From 2012 to 2014, 15,000 brown trout were released annually into the Navizence River from the Sierre fish farm.
Flooding history
The Navizence experienced two floods that resulted in a significant overflow. The first flood occurred in August 1834, caused by the obstruction of the river's flow at the Zinal Glacier by a proglacial lake. This obstruction was a result of an exceptionally dry summer, heavy rainfall, and a south wind. When the lake suddenly burst, it swept away several bridges, barns, stables, and mills in Ayer. In Chippis, the river deposited a layer of sand and silt measuring between 1 and 2 meters.
In July 2018, a new overflow occurred due to a violent thunderstorm covering 35 km2 and the melting of large amounts of snow. The Navizence reached a 120 m3/s flow, which is half the Rhône nominal flow. The overflow impacted various areas between Zinal and Chippis: the FC Anniviers football stadium was submerged, and a bridge in Chippis had to be urgently demolished by rescuers. The sewage treatment plant in Anniviers at Fang suffered significant damage, leading to the direct discharge of wastewater from Zinal and Grimentz into the Navizence. The estimated damage from the event was between 30 and 40 million Swiss francs.
Activities
Water use
Water from the Navizence has been utilized for hydroelectric power generation since 1908 in Chippis by the "Navizence" hydroelectric plant. This plant initially supplied electricity to the Alusuisse factory in Chippis from a water intake in Vissoie. A new plant harnessing the Navizence was constructed in Vissoie in 1909, and the "Navizence" plant underwent renovation in the 1950s. The Moiry Dam was constructed between 1954 and 1958 on the Gougra River, along with a network of galleries in the Anniviers Valley, enabling water to be pumped from the Navizence from Mottec to the dam. Local hydroelectric operators have a total of nine intakes in the Navizence basins. The maintenance of a minimum discharge at each intake is regulated by the Federal Law on Water Protection of January 24, 1991. At the Vissoie intake, the Navizence flow must be at least 470 l/s before abstraction.
There are ten groundwater drinking water intakes in the Navizence watershed. Additionally, water is extracted at eight locations along the banks of the Navizence to supply irrigation channels (bisses): the Gillou alp, the Sarrasin channel in Saint-Jean and Chalais, the Briey channel in Saint-Luc and Chalais, the Chararogne and Ricard channel in Chalais and Chippis, as well as the Lacher, Tinda, and Neuf Bénou channel. Furthermore, a sewage treatment plant releases treated water into the Navizence at Fang.
Tourism
Since 1922, the Niouc suspension bridge has spanned the Navizence River at a height of nearly 200 meters. Visitors can cross the bridge and participate in activities such as bungee jumping or pendulum jumping. In 2021, a via ferrata route was made accessible either by crossing the suspension bridge or starting from Chippis.
Environmental protection
Two sectors of the Navizence watershed are classified in the federal inventory of alluvial areas of national importance: the Plat de la Lée (30.85 ha) and the Zinal Glacier (186.09 ha). Additionally, the downstream part of the watershed intersects the Pfynwald-Illgraben area, which is included in the Federal Inventory of Landscapes and Natural Monuments.
Among the aquifers in the watershed, 34% are highly vulnerable to pollution penetration, while 24% have a high vulnerability. This indicates that these aquifers lack adequate protection from low-permeability layers.
Fishing is prohibited in the section of the Navizence between the mouth of the Pinsec stream and the Vissoie accumulation basin, as it is designated as a reserve. However, fishing is permitted downstream of the Gougra mouth with a cantonal permit.
In culture
The theater troupe in Vissoie is called "Les Compagnons de la Navizence." In 1993, an exhibition titled Oh! Navizence, conceptualized by Jean-Jacques Le Joncour, was held in Sierre. The exhibition depicted the banks of the Navizence in a post-apocalyptic future scenario set in 2009.
Notes
References
Bibliography
External links
Anniviers
Moming Glacier
Zinal Glacier
List of rivers of Switzerland
Rhône
Val d'Anniviers
For all the points mentioned on this page, see:
OpenStreetMap
archive
Bing Maps
archive
download in KML format
archive
Rivers of Valais
Rhône basin
Hydrology | Navizence | [
"Chemistry",
"Engineering",
"Environmental_science"
] | 2,581 | [
"Hydrology",
"Environmental engineering"
] |
76,669,457 | https://en.wikipedia.org/wiki/John%20R.%20Ragazzini%20Award | The John R. Ragazzini Education Award is an annual accolade bestowed by the American Automatic Control Council (AACC) since 1979, named in honor of John R. Ragazzini, a pioneering American electrical engineer and educator. This prestigious award recognizes outstanding contributions to education in the field of automatic control.
Overview
The award celebrates those who have made significant advancements in control education in the United States, either through teaching, textbook authorship, mentoring, or other forms of educational activity that promote the discipline of automatic control. It is one of the highest honors in the field of control education and underscores the commitment to academic excellence and innovation in engineering education.
Recipients
1979: John R. Ragazzini
1980: Michael Athans
1981: Yasundo Takahashi
1982: Arthur E. Bryson
1983: Charles A. Desoer
1984: H. M. Paynter
1985: Gene F. Franklin
1986: Thomas Kailath
1987: George J. Thaler
1988: Wallace E. Vander Velde
1989: W. Harmon Ray
1990: Kumpati S. Narendra
1991: Michael J. Rabins
1992: Thomas F. Edgar
1993: Dale E. Seborg
1995: J. Boyd Pearson
1996: David M. Auslander
1997: William R. Perkins
1998: Peter Dorato
1999: Katsuhiko Ogata
2000: Hassan K. Khalil
2001: Dimitri P. Bertsekas
2002: Robert F. Stengel
2003: Stephen P. Boyd
2004: Mark W. Spong
2005: S. Shankar Sastry
2006: Masayoshi Tomizuka
2007: Manfred Morari
2008: Stephen Yurkovich
2009: George Stephanopoulos
2010: Tzyh Jong Tarn
2011: James B. Rawlings
2013: Mathukumalli Vidyasagar
2014: Roger W. Brockett
2015: Magnus Egerstedt
2016: Brian D. O. Anderson
2017: Miroslav Krstić
2018: Frank L. Lewis
2019: Richard M. Murray
2020: Naomi Leonard
2021: Graham Goodwin
2022: Bonnie Ferri
2023: Richard D. Braatz
2024: John D. Hedengren
See also
List of people in systems and control
List of engineering awards
American Automatic Control Council
List of education awards
References
External links
AACC John R. Ragazzini Education Award page
Systems sciences awards
Control engineering
Education awards | John R. Ragazzini Award | [
"Engineering"
] | 487 | [
"Control engineering"
] |
76,669,611 | https://en.wikipedia.org/wiki/Carrimycin | Carrimycin is a macrolide antibiotic. It was approved by the National Medical Products Administration of China in 2019. It is approved for the treatment of acute tracheal bronchitis caused by Haemophilus influenzae, Streptococcus pneumoniae, and for the treatment of acute sinusitis caused by S. pneumoniae, H. influenzae, Streptococcus pyogenes, Moraxella catarrhalis, and Staphylococcus. Carrimycin is mainly used for the treatment of upper respiratory tract infections.
Carrimycin is a mixture of related chemical compounds, carrimycin I through III, which are each ester derivatives of spiramycin.
Carrimycin has also been investigated for the treatment of COVID-19.
References
Macrolide antibiotics
Dimethylamino compounds
Tetrahydropyrans
Methoxy compounds
Esters
Diols
Lactones | Carrimycin | [
"Chemistry"
] | 195 | [
"Organic compounds",
"Esters",
"Functional groups"
] |
76,671,176 | https://en.wikipedia.org/wiki/JANNAF | The JANNAF Interagency Propulsion Committee (JANNAF IPC, or simply JANNAF) is a joint-agency committee chartered by the USDOD and NASA. JANNAF is composed of two committees: the Technical Committee and the Programmatic & Industrial Base (PIB) Committee. The Technical Committee is itself divided into subcommittees focused on specific technology areas of mutual interest to the DoD and NASA. The JANNAF PIB Committee is a forum for the discussion of strategic program planning and industrial base capabilities in the area of rocket propulsion and energetic systems and components for military and civil space, tactical and strategic missiles, and large gun systems.
JANNAF was re-chartered on June 19th 2014 with the signatures of Frank Kendall III, Under Secretary of Defense for Acquisition, Technology, and Logistics (USD(AT&L)) and Robert Lightfoot Jr., Associate Administrator of the National Aeronautics and Space Administration (NASA)
References
External links
NIST-JANAF Thermochemical Tables
JANNAF/GL-2016-0001 Simulation Credibility - Advances in Verification, Validation, and Uncertainty Quantification
JANNAF DRAFT: Test and Evaluation Guideline for Liquid Rocket Engines
United States military associations
Aerospace engineering organizations
1945 establishments in Maryland | JANNAF | [
"Engineering"
] | 255 | [
"Aeronautics organizations",
"Aerospace engineering organizations",
"Aerospace engineering"
] |
76,671,601 | https://en.wikipedia.org/wiki/UGC%20934 | UGC 934, known as PGC 5085, is a large spiral galaxy about 470 million light-years away from the solar system. It is located in the constellation of Pisces and about 285,000 thousand light-years in diameter.
With its neighboring galaxy PGC 212740, they together form the galaxy pair, VV 341. They are also known as Arp 70, the 70th number in the Atlas of Peculiar Galaxies, created by Halton Arp. In this class, they fall under spiral galaxies that have a small high-surface brightness companions.
According to Laurikainen, Salo & Aparicio, UGC 934 and the neighboring galaxy are examples of M51- type galaxies, i.e. a system where a large galaxy with two spiral arms is seen interacting with a smaller companion. It is likely the interaction with PGC 212740 would result UGC 934 having grand design spiral arms.
The SIMBAD database and by Lacerda et al. (2020) classifies UGC 934 as a Seyfert type 2 galaxy with an active galactic nucleus.
A giant H II region in the galaxy has been discovered in one of its spiral arms. It has a luminosity of (7.5 ± 0.5) x 1040 ergs−1. Additionally, the rate of star formation in UGC 934 is 0.59 ± 0.04 M⊙ yr−1.
Supernovae
Two supernovae have been discovered in UGC 934 so far, SN 2003lc and SN 2005ly.
SN 2003lc
SN 2003lc, was an apparent supernova located 32.1" west and 10.7" north of its nucleus. It was discovered by two astronomers, T. Puckett and L. Cox in December 2003, via an unfiltered CCD frame but no supernova classification was confirmed.
SN 2005ly
SN 2005ly was discovered by T. Puckett and G. Sostero in December 2005, using another unfiltered CCD frame observed with the Puckett Observatory supernova patrol telescope in Ellijay, Georgia. It was located 5".4 east and 18".2 south. Unlike SN 2003lc, SN 2005ly was classified a type-IIn supernova by astronomers from Harvard-Smithsonian Center for Astrophysics and the National Optical Astronomy Observatory who obtained its spectrum. They confirmed it has Balmer emission lines, having both a narrow and wide component, and a blue continuum indicating a relative young age for the spectrum.
References
Interacting galaxies
Spiral galaxies
Pisces (constellation)
00934
070a
5085
5085
+05-04-042
J012328.30+304703.9 | UGC 934 | [
"Astronomy"
] | 566 | [
"Pisces (constellation)",
"Constellations"
] |
76,671,625 | https://en.wikipedia.org/wiki/Furcula%20granulifer | Furcula is a genus of extinct plant from Late Triassic Greenland. It contains one species, F. granulifer. The leaves of Furcula have complex net-like veins like those of angiosperms (flowering plants); because of this, it was long considered a possible stem-group angiosperm. However, a recent reinvestigation suggests it is a peltasperm (a type of "seed fern") that convergently evolved angiosperm-like veins.
References
Triassic plants
Prehistoric plants
Fossils of Greenland
Peltaspermales
Rhaetian first appearances
Late Triassic extinctions
Fossil taxa described in 1932 | Furcula granulifer | [
"Biology"
] | 131 | [
"Prehistoric plants",
"Plants"
] |
76,672,405 | https://en.wikipedia.org/wiki/IC%204461 | IC 4461 is a spiral galaxy located in the Boötes constellation, located at distance of 417 million light-years from both the Milky Way and Andromeda Galaxy.
The galaxy was first discovered by Stephane Javelle on June 22, 1895 who found it as a faint and round object. It is listed as PGC 52119 by Javelle. Together with IC 4462, they make up Arp 95 in the Atlas of Peculiar Galaxies, which they fall under galaxies with elliptical companions. IC 4461 is sometimes confused with another spiral galaxy PGC 52120, which lies at a much further distance of 855 million light-years.
References
Boötes
Spiral galaxies
52119
095
4461
J14350187+2632378
9384
+05-34-077
Astronomical objects discovered in 1895
Interacting galaxies | IC 4461 | [
"Astronomy"
] | 175 | [
"Boötes",
"Constellations"
] |
76,672,588 | https://en.wikipedia.org/wiki/LHASA | LHASA (Logic and Heuristics Applied to Synthetic Analysis) is a computer program developed in 1971 by the research group of Elias James Corey at the Harvard University Department of Chemistry. The program uses artificial intelligence techniques to discover sequences of reactions which may be used to synthesize a molecule. This program was one of the first to use a graphical interface to input and display chemical structures.
References
Computational chemistry software
Total synthesis
Organic synthesis | LHASA | [
"Chemistry",
"Technology"
] | 89 | [
"Software stubs",
"Computational chemistry software",
"Organic synthesis",
"Chemistry software",
"Computational chemistry",
"Chemical synthesis",
"Total synthesis",
"Computing stubs"
] |
76,672,591 | https://en.wikipedia.org/wiki/IC%204462 | IC 4462 is an elliptical galaxy located in the Boötes constellation. It is located 417 million light-years away from the Solar System and was found by Stephane Javelle on June 22, 1895 the same day he discovered IC 4461, a spiral galaxy. It is gravitationally interacting with IC 4461 and possibly might merge with the latter in the future. Both galaxies form Arp 95, which they are classified under galaxies that have elliptical companions. Sometimes the galaxy is confused with IC 4461.
References
Elliptical galaxies
Boötes
4462
095
52123
J14350418+2632268
+05-34-078
Astronomical objects discovered in 1895
Interacting galaxies | IC 4462 | [
"Astronomy"
] | 144 | [
"Boötes",
"Constellations"
] |
76,672,760 | https://en.wikipedia.org/wiki/Intraoral%20scanner | An intraoral scanner is a device used in dentistry to capture digital images of the inside of the mouth. These images are an alternative to traditional dental impressions.
Introduction
Intraoral scanners are devices used in dentistry which create digital scans of the teeth and soft tissue anatomy. These devices replace the use of dental putty impressions by using a light source and image sensors to record the tissues inside the mouth accurately and create a virtual alternative to traditional impression plaster models
Background
Dental impressions are the first step for creating a dental prosthesis. The most common material used for traditional impressions is polyvinyl siloxane, however this material has a poor smell and odour which makes it not favourable for patient or dentist alike. Intraoral scanners have been introduced into dentistry to make the impression process less uncomfortable to the patient.
Function
Intraoral scanners are placed into the mouth and emit a laser or light source which hits the teeth and surrounding tissues, this light is then captured by image sensors and using point clouds, a 3D digital model is made.
Use
Intraoral scanners are of high use in CAD/CAM dental use. This is where a computer system can design and mill dental prosthetic framework, such as a crown or bridge, from a digital model.
As these scanners record images of the teeth, they can be used to identify the correct shade for a dental crown.
Benefits and limitations
These devices improve time-management as they show the image in real time. They are also quicker than plaster impressions and more comfortable to the dental patient.
Intraoral scanners have shown to be beneficial to patients suffering from a large gap-reflex which prevents traditional plaster impressions from being taken.
Due to the ‘impressions’ being digital, it means there is no risk of them breaking in transit in comparison with traditional models where they frequently break.
The scanners create a 3D digital scan replicating the intraoral cavity.
They can detect dental caries, erosion and issues with the periodontium.
Some research has found that digital impressions using intraoral scanners may not be as accurate as traditional plaster impressions.
References
Dental technology
Image scanners | Intraoral scanner | [
"Biology"
] | 436 | [
"Dental technology",
"Medical technology"
] |
76,672,792 | https://en.wikipedia.org/wiki/UGC%204457 | UGC 4457 known as PGC 23935, is a barred spiral galaxy, containing an active galactic nucleus in the Cancer constellation. It is located 500 million light-years away from the Solar System and has a diameter of 290,000 light-years, making it slightly more massive compared to the Milky Way. The galaxy is moving away at a speed of 11,162 kilometers per second.
UGC 4457 is interacting with the compact galaxy, PGC 23937. Together, they form Arp 58 and are classified under spiral galaxies that have small companions with high surface brightness. In addition, this interacting galaxy pair is also an M51 type system.
UGC 4457 shows disturbed spiral arms, indicating signs of velocity disturbance levels and regions of scattered ionized gas, typically normal for interacting galaxies. A faint spiral bridge can be seen thus representing the remains of an older mode of spiral waves.
References
Barred spiral galaxies
Interacting galaxies
Cancer (constellation)
4457
058
23935
+03-22-017
23935 | UGC 4457 | [
"Astronomy"
] | 207 | [
"Cancer (constellation)",
"Constellations"
] |
58,368,757 | https://en.wikipedia.org/wiki/Clary%20DE-60 | The Clary DE-60 was an early transistorized digital computer made by Clary Corporation. It was a compact (desk-sized) general-purpose computer intended for both scientific and business applications. It operated on 18-digit binary-coded decimal words used fixed-point arithmetic. Main memory was a 32-word magnetic drum memory. Input and output devices included a console keyboard, printer, paper tape and punched card system. For programming, the system used sequential instructions from the keyboard and plug-boards.
Custom modules for trigonometric and other functions could be installed.
The system was introduced in 1959. By 1961, about 18 systems were operating or on order. Clary Corporation was founded by Hugh L. Clary in 1939. Today the company manufactures products such as uninterruptible power supply systems.
References
External links
Photos:
1950s computers
Transistorized computers | Clary DE-60 | [
"Technology"
] | 175 | [
"Computing stubs",
"Computer hardware stubs"
] |
58,373,976 | https://en.wikipedia.org/wiki/Generalized%20periodic%20epileptiform%20discharges | Generalized periodic epileptiform discharges (GPEDs) are very rare abnormal patterns found in EEG.
Types
Based on the interval between the discharges they are classified as:
Periodic short-interval diffuse discharges (PSIDDs)
Periodic long-interval diffuse discharges (PLIDDs)
Burst suppression patterns
References
Electroencephalography
Neuroscience | Generalized periodic epileptiform discharges | [
"Biology"
] | 73 | [
"Neuroscience"
] |
58,374,837 | https://en.wikipedia.org/wiki/Active%20ester | In organic chemistry, an active ester is an ester functional group that is highly susceptible toward nucleophilic attack. Activation can be imparted by modifications of the acyl or the alkoxy components of a normal ester, say ethyl acetate. Typical modifications call for electronegative substituents. Active esters are employed in both synthetic and biological chemistry.
Reactivity
Active esters are mainly used as acylating agents. They undergo the same reactions as their unactivated analogues but do so more rapidly. They are prone to hydrolysis, for example. Of great interest is the enhanced reactivity of active esters toward amines to give amides.
Examples
Thioesters are prominent active esters, as illustrated by the esters of coenzyme A.
In synthetic chemistry, active esters include derivatives of nitrophenols and pentafluorophenol. Active esters are often used in peptide synthesis, e.g., N-hydroxysuccinimide, hydroxybenzotriazole. Active esters of acrylic acid are precursors to polymers with reactive side chains.
The concept of active esters extends to esters of phosphoric and sulfuric acids. One such case is dimethylsulfate, a strong methylating agent.
References
Functional groups
Esters | Active ester | [
"Chemistry"
] | 282 | [
"Organic compounds",
"Esters",
"Functional groups"
] |
58,376,089 | https://en.wikipedia.org/wiki/EA-2192 | EA-2192 is an extremely toxic degradation product of the VX, a very potent nerve agent. It is a white solid that is very soluble and stable in water.
EA-2192 is an extremely potent acetylcholinesterase inhibitor. It is almost as toxic as VX itself.
EA-2192 behaves similar to aged soman as it is the dealkylated form of VX and cannot be reversed with common oxime reactivators.
See also
Nerve agent
References
V-series nerve agents
Phosphonothioates
Phosphonic acids
Acetylcholinesterase inhibitors
Diisopropylamino compounds | EA-2192 | [
"Chemistry"
] | 131 | [
"Phosphonothioates",
"Functional groups",
"Organic compounds",
"Organic compound stubs",
"Organic chemistry stubs"
] |
58,376,884 | https://en.wikipedia.org/wiki/Elmer%20and%20Elsie%20%28robots%29 | Elmer and Elsie (ELectroMEchanical Robot, Light-Sensitive) were two electronic robots that were built in the late 1940s by neurobiologist and cybernetician William Grey Walter. They were the first robots in history that were programmed to "think". Elmer and Elsie were often labeled as tortoises because of how they were shaped and the manner in which they moved. They were capable of phototaxis, which is the movement that occurs in response to light stimulus.
Description
Elmer and Elsie, or the "tortoises" as they were known, were constructed between 1948 and 1949 using war surplus materials and old alarm clocks. They had a single light or touch sensor hooked up to two different paths that ran two different motors acting as two separate neuron brains. The robots had a plastic shell which was phototropic in that it could follow light and act as a bumper sensor.
The robots were designed to show the interaction between both light-sensitive and touch-sensitive control mechanisms which were basically two nerve cells with visual and tactile inputs. These systems interacted with the motor drive in such a way that the tortoises were actually finding their way around obstacles.
In one experiment a light was placed on the nose of one of the tortoises. It appeared that the robot was looking at itself in a mirror. Its light began flickering and the robot started shaking as if excited to see itself in the mirror. Walter argued that if this behavior were seen in an animal it "might be accepted as evidence of some degree of self-awareness."
Legacy
Elmer and Elsie inspired later generations of robotics researchers such as Rodney Brooks, Hans Moravec and Mark Tilden. Rodney Brooks' "Intelligence without Representation" is in many ways a modern take on Elmer and Elsie. Modern replicas of the tortoises may be found in the form of BEAM robotics. An original tortoise is on display in London UK in the Science Museum's Making the Modern World gallery. In 1995, one was replicated by Owen Holland, of the University of the West of England, which used some of the original parts. An original tortoise as seen at the Festival of Britain is in the collection of the Smithsonian Institution.
See also
Robotic vacuum cleaner
Turtle (robot)
References
Robots
Cybernetics | Elmer and Elsie (robots) | [
"Physics",
"Technology"
] | 467 | [
"Physical systems",
"Machines",
"Robots"
] |
58,377,656 | https://en.wikipedia.org/wiki/Genghis%20%28robot%29 | Genghis was a six legged insect-like robot that was created by roboticist Rodney Brooks at MIT around 1991. Brooks wanted to solve the problem of how to make robots intelligent and suggested that it is possible to create robots that displayed intelligence by using a "subsumption architecture" which is a type of reactive robotic architecture where a robot can react to the world around them. His paper "Intelligence Without Representation", which is still widely respected in the fields of robotics and Artificial Intelligence, further outlines his theories on this.
Design
The design of the Genghis robot was inspired by insects who have limited brain functions yet possess tremendous functionality. In order to mimic this trait found in insects Brooks "removed all cognition processors from Genghis and left only the sensors and the code/hardware to allow it to walk". This enabled Genghis to link sensation to an action taken where the robot did not have any pre-planned path to follow but took action as each sensor detected an obstacle. With Genghis, Brooks pioneered his "sensation-action theory of intelligence which was to bypass explicit cognition hubs in favor of pairing perception more directly with action".
Genghis was not designed to have a central controller to direct all possible functions in the robot, particularly in the legs. Instead, each leg had its own built-in sensors that would sense the various obstacles in its path. Each leg was programmed with a few basic behaviors and knew how to react under different scenarios based on sensor feedback. The act of walking became a coordinated effort between all of the legs resulting in the robots movement. These processes exist independently, run at all times and fire whenever the sensory preconditions are true.
Genghis was designed to navigate difficult terrain with many obstacles and elevations. In order to achieve this type of functionality while reducing overall complexity Brooks created a method of finite-state machine thought that relied on "layered processing"; a basic layering of new traits over older ones. In Genghis the control system was organized into "eight incremental layers: Stand up, Simple Walk, Force Balancing, Leg Lifting, Whiskers, Pitch Stabilization, Prowling and Steered Prowling". On a processing level the complexity of each of the eight layers of the final movement are addressed separately by each layer, reducing the burden of complex processing from the processors at each level.
Genghis now resides in the Smithsonian Air and Space Museum.
References
Robots | Genghis (robot) | [
"Physics",
"Technology"
] | 496 | [
"Physical systems",
"Machines",
"Robots"
] |
58,377,746 | https://en.wikipedia.org/wiki/Path%20of%20the%20Puma | Path of the Puma: The Remarkable Resilience of the Mountain Lion, by Jim Williams, is a non-fiction book presenting the research of the author, a wildlife biologist and supervisor for Montana Fish, Wildlife and Parks' Region 1 in Kalispell. Williams also discusses DNA research conducted by others on these animals, and makes the case for coexistence with these big, wild cats.
Synopsis
With a foreword by Doug Chadwick, the book chronicles Williams' journey, from his early work at a Florida marine park, to his conversion to "a lifelong devotee of the species". Williams has fitted Puma concolors (also known as cougars and mountain lions) with radio collars and has installed cameras in their caves to track and study them. According to Mountain West News, "Montana-based wildlife biologist Jim Williams celebrates wildlife research and conservation of ghost cats from Canada's Yukon Territory to Tierra del Fuego in Argentina and Chile..."
Critical reception
Path of the Puma has received positive reviews. Publishers Weekly said, "Williams writes movingly of the challenges these animals face, many due to human encroachment on their habitats. He makes a strong case for the necessity of preserving—or at least peacefully coexisting with—the puma." Kirkus Reviews noted, "While the book is an undisguised conservationist's plea ... it is not a harangue. The author's passion and his firsthand knowledge of his subject make the narrative highly readable. A noteworthy feature of this work is the presence of numerous full-color photographs..." Kirkus concluded, "A handsome book that is well-balanced, instructive, and authoritative." The Natural History Book Service wrote that the puma's story, "...is fascinating for the lessons it can afford the protection of all species in times of dire challenge and decline."
Susan Waggoner of PressReader notes Williams' "...enthusiasm for nature and animals jumps off every page... Williams's writing is expert, friendly, and interesting. Well organized and clearly presented, information emerges from field work examples, such as the tracking studies that showed that pumas feed almost exclusively on wild prey rather than domestic herds." Tristan Scott of the Flathead Beacon wrote, "Path of the Puma doesn't sugarcoat the risks of predators living among humans — mountain lions live at the intersection of human landscapes, livelihoods and lifestyles — but it points out the critical role predatory species play in the natural world."
Awards
In March 2019, Path of the Puma was named a finalist in two categories for the Foreword INDIES Book of the Year Awards. In June, it was declared the INDIES 2018 Gold winner for Nature in the Adult Non-Fiction category, a category described as "Books that examine not only nature and its inhabitants, but people's connection with nature. Authors present their personal responses to the outdoors, comment on environmental issues, and demonstrate how each person can enjoy and relate to nature." Path of the Puma also won the INDIES 2018 Bronze award for Ecology and Environment in Adult Non-fiction. That award is described, "Books that comment on environmental themes, particularly as applied to the relationships between man, society, and the environment. Often, environmental literature is understood to promote care and concern for the environment and advocates a more thoughtful and ecologically sensitive relationship of man with nature."
References
External links
Path Of The Puma With Jim Williams (video, 28:57)
This is the Author, S4, E57: Jim Williams, Robert Pondiscio, and Rhonda Magee (audio, first 6:10 minutes)
2018 non-fiction books
American non-fiction books
Ecology books
Nature books
Wildlife conservation
Zoology books
Non-fiction books about cats | Path of the Puma | [
"Biology"
] | 787 | [
"Wildlife conservation",
"Biodiversity"
] |
58,377,750 | https://en.wikipedia.org/wiki/NitrosBase | NitrosBase is a Russian
high-performance multi-model database system. The database system supports relational, graph and document database models.
History
The developer initially implemented the database as a triplestore, being a Semantic Web pioneer in Russia. Remodelling into a multi-model database was supported by the Skolkovo Innovation Center in 2017.
The database is used in information systems that support the health-care reform in modern Russia.
Characteristics
In NitrosBase, all data are stored in the format of the internal graph model, while data in other models are their views (representations; similar to SQL views). Regardless of the model in which format data were imported, it is possible to query them using the same query language thereby uniformly addressing data imported in different models.
Moreover, it is possible to query data in any model using query language that is native for that model. NitrosBase supports the following languages:
SQL (with elements of object syntax) – for querying data in relational view;
SPARQL and Gremlin-style language Graph-it – for querying data in graph view;
JSONiq and MongoDB Query – for querying data in document view.
Implementation details
The internal graph model is close to RDF* which is used in Blazegraph and Amazon Neptune. That allows it to treat the internal data graph both as RDF graph and as Property Graph, performing queries both in SPARQL and Gremlin-style languages.
Instead of indexes based on B+-trees traditionally used in graph databases, NitrosBase uses a sparse link index of its own devising. Another source of performance gain is storage optimization on the physical level in order to reduce the number of random access operations.
Like memSQL, NitrosBase translates a query into C++ code.
Awards and achievements
Nitrosbase-derived product MS SQL Server Accelerator was awarded first prize at the Silicon Valley Open Doors conference in 2009 and named "startup of the day" of the Microsoft BizSpark program on 3 March 2010.
References
External links
Official website
Graph databases
Document-oriented databases
Relational database management systems
Proprietary database management systems | NitrosBase | [
"Mathematics"
] | 445 | [
"Graph databases",
"Mathematical relations",
"Graph theory"
] |
58,378,131 | https://en.wikipedia.org/wiki/Henry%20Mahler | Henry Ralph Mahler (1921–1983) was an Austrian-born American biochemist known for his research in the fields of both mitochondrial biogenesis and neurochemistry.
Biography
Mahler was born in 1921 in Vienna, Austria. He emigrated to the United States in 1938, where he enrolled in Swarthmore College, from which he graduating in 1943. The same year, he enrolled at the University of California, Berkeley, where he received his Ph.D. in 1948. At Berkeley, he conducted research on aspects of mechanism of photosynthesis in plant chloroplasts under the direction of Nobel Prize winner Melvin Calvin. He then completed his postdoc at the Texas Research Foundation before joining the faculty of the University of Wisconsin, Madison's Institute for Enzyme Research in 1949 as a senior research associate. In 1951, he became an assistant professor there.
In 1955, he moved to Bloomington, Indiana to join the faculty of Indiana University as an associate professor. He was promoted to full professor at Indiana University in 1957, and was named research professor of biochemistry and neural sciences as well as National Institutes of Health Research Career Investigator there in 1966. In the 1976–77 academic year, he served as an honor fellow at University College London, a visiting professor at the C.N.R.S. Institute of Molecular Genetics, Gif-sur-Yvette, France, and visiting professor at the Institut fur Allgemeine Biochemie of the University of Vienna. During Professor Mahler's career, he published more than 300 research articles with his many former students, postdoctoral fellows and colleagues. He also coauthored two editions (1966 and 1971) of a well known textbook Biological Chemistry with his colleague Professor Eugene H. Cordes. In 1972, he collaborated with his Indiana University colleague Rudolf Raff on a paper criticizing the theory that mitochondria in the cells of higher organisms originated as independent, single-celled organisms.
He died on July 6, 1983, of heart failure at Woods Hole, Massachusetts.
References
External links
Chemistry Tree - Henry R. Mahler
Austrian emigrants to the United States
1921 births
1983 deaths
Neurochemists
Swarthmore College alumni
University of California, Berkeley alumni
University of Wisconsin–Madison faculty
Indiana University faculty
Scientists from Vienna
20th-century American biochemists | Henry Mahler | [
"Chemistry"
] | 470 | [
"Biochemistry stubs",
"Biochemists",
"Biochemist stubs"
] |
58,381,580 | https://en.wikipedia.org/wiki/International%20Journal%20of%20Technology%20Assessment%20in%20Health%20Care | The International Journal of Technology Assessment in Health Care is a bimonthly peer-reviewed healthcare journal covering health technology assessment. Established in 1985, it is published by Cambridge University Press, and is the official journal of Health Technology Assessment International. The editor-in-chief is Wendy Babidge (Royal Australasian College of Surgeons). According to the Journal Citation Reports, the journal has a 2022 impact factor of 3.2, ranking it 18th out of 31 journals in the category "Medical Informatics", 48th out of 106 in the category "Health Care Sciences & Services", and 106th out of 207 in the category "Public, Environmental & Occupational Health".
References
External links
Biomedical informatics journals
Cambridge University Press academic journals
Academic journals established in 1985
Bimonthly journals
English-language journals
Healthcare journals
Public health journals | International Journal of Technology Assessment in Health Care | [
"Biology"
] | 169 | [
"Bioinformatics",
"Biomedical informatics journals"
] |
58,383,744 | https://en.wikipedia.org/wiki/Separation%20principle%20in%20stochastic%20control | The separation principle is one of the fundamental principles of stochastic control theory, which states that the problems of optimal control and state estimation can be decoupled under certain conditions. In its most basic formulation it deals with a linear stochastic system
with a state process , an output process and a control , where is a vector-valued Wiener process, is a zero-mean Gaussian random vector independent of , , and , , , , are matrix-valued functions which generally are taken to be continuous of bounded variation. Moreover, is nonsingular on some interval . The problem is to design an output feedback law which maps the observed process to the control input in a nonanticipatory manner so as to minimize the functional
where denotes expected value, prime () denotes transpose. and and are continuous matrix functions of bounded variation, is positive semi-definite and is positive definite for all . Under suitable conditions, which need to be properly stated, the optimal policy can be chosen in the form
where is the linear least-squares estimate of the state vector obtained from the Kalman filter
where is the gain of the optimal linear-quadratic regulator obtained by taking and deterministic, and where is the Kalman gain. There is also a non-Gaussian version of this problem (to be discussed below) where the Wiener process is replaced by a more general square-integrable martingale with possible jumps. In this case, the Kalman filter needs to be replaced by a nonlinear filter providing an estimate of the (strict sense) conditional mean
where
is the filtration generated by the output process; i.e., the family of increasing sigma fields representing the data as it is produced.
In the early literature on the separation principle it was common to allow as admissible controls all processes that are adapted to the filtration . This is equivalent to allowing all non-anticipatory Borel functions as feedback laws, which raises the question of existence of a unique solution to the equations of the feedback loop. Moreover, one needs to exclude the possibility that a nonlinear controller extracts more information from the data than what is possible with a linear control law.
Choices of the class of admissible control laws
Linear-quadratic control problems are often solved by a completion-of-squares argument. In our present context we have
in which the first term takes the form
where is the covariance matrix
The separation principle would now follow immediately if were independent of the control. However this needs to be established.
The state equation can be integrated to take the form
where is the state process obtained by setting and is the transition matrix function. By linearity, equals
where . Consequently,
but we need to establish that does not depend on the control. This would be the case if
where is the output process obtained by setting . This issue was discussed in detail by Lindquist. In fact, since the control process is in general a nonlinear function of the data and thus non-Gaussian, then so is the output process . To avoid these problems one might begin by uncoupling the feedback loop and determine an optimal control process in the class of stochastic processes that are adapted to the family of sigma fields. This problem, where one optimizes over the class of all control processes adapted to a fixed filtration, is called a stochastic open loop (SOL) problem. It is not uncommon in the literature to assume from the outset that the control is adapted to ; see, e.g., Section 2.3 in Bensoussan, also van Handel and Willems.
In Lindquist 1973 a procedure was proposed for how to embed the class of admissible controls in various SOL classes in a problem-dependent manner, and then construct the corresponding feedback law. The largest class of admissible feedback laws consists of the non-anticipatory functions such that the feedback equation has a unique solution and the corresponding control process is adapted to .
Next, we give a few examples of specific classes of feedback laws that belong to this general class, as well as some other strategies in the literature to overcome the problems described above.
Linear control laws
The admissible class of control laws could be restricted to contain only certain linear ones as in Davis. More generally, the linear class
where is a deterministic function and is an kernel, ensures that is independent of the control. In fact, the Gaussian property will then be preserved, and will be generated by the Kalman filter. Then the error process is generated by
which is clearly independent of the choice of control, and thus so is .
Lipschitz-continuous control laws
Wonham proved a separation theorem for controls in the class , even for a more general cost functional than J(u). However, the proof is far from simple and there are many technical assumptions. For example, must square and have a determinant bounded away from zero, which is a serious restriction. A later proof by Fleming and Rishel is considerably simpler. They also prove the separation theorem with quadratic cost functional for a class of Lipschitz continuous feedback laws, namely , where is a non-anticipatory function of which is Lipschitz continuous in this argument. Kushner proposed a more restricted class , where the modified state process is given by
leading to the identity .
Imposing delay
If there is a delay in the processing of the observed data so that, for each , is a function of , then , , see Example 3 in Georgiou and Lindquist. Consequently, is independent of the control. Nevertheless, the control policy must be such that the feedback equations have a unique solution.
Consequently, the problem with possibly control-dependent sigma fields does not occur in the usual discrete-time formulation. However, a procedure used in several textbooks to construct the continuous-time as the limit of finite difference quotients of the discrete-time , which does not depend on the control, is circular or a best incomplete; see Remark 4 in Georgiou and Lindquist.
Weak solutions
An approach introduced by Duncan and Varaiya and Davis and Varaiya, see also Section 2.4 in Bensoussan
is based on weak solutions of the stochastic differential equation. Considering such solutions of
we can change the probability measure (that depends on ) via a Girsanov transformation so that
becomes a new Wiener process, which (under the new probability measure) can be assumed to be unaffected by the control. The question of how this could be implemented in an engineering system is left open.
Nonlinear filtering solutions
Although a nonlinear control law will produce a non-Gaussian state process, it can be shown, using nonlinear filtering theory (Chapters 16.1 in Lipster and Shirayev
), that the state process is conditionally Gaussian given the filtration . This fact can be used to show that is actually generated by a Kalman filter (see Chapters 11 and 12 in Lipster and Shirayev). However, this requires quite a sophisticated analysis and is restricted to the case where the driving noise is a Wiener process.
Additional historical perspective can be found in Mitter.
Issues on feedback in linear stochastic systems
At this point it is suitable to consider a more general class of controlled linear stochastic systems that also covers systems with time delays, namely
with a stochastic vector process which does not depend on the control. The standard stochastic system is then obtained as a special case where , and . We shall use the short-hand notation
for the feedback system, where
is a Volterra operator.
In this more general formulation the embedding procedure of Lindquist defines the class of admissible feedback laws as the class of non-anticipatory functions such that the feedback equation has a unique solution and is adapted to .
In Georgiou and Lindquist a new framework for the separation principle was proposed. This approach considers stochastic systems as well-defined maps between sample paths rather than between stochastic processes and allows us to extend the separation principle to systems driven by martingales with possible jumps. The approach is motivated by engineering thinking where systems and feedback loops process signals, and not stochastic processes per se or transformations of probability measures. Hence the purpose is to create a natural class of admissible control laws that make engineering sense, including those that are nonlinear and discontinuous.
The feedback equation has a unique strong solution if there exists a non-anticipating function such that satisfies the equation with probability one and all other solutions coincide with with probability one. However, in the sample-wise setting, more is required, namely that such a unique solution exists and that holds for all , not just almost all. The resulting feedback loop is deterministically well-posedin the sense that the feedback equations admit a unique solution that causally depends on the input for each input sample path.
In this context, a signal is defined to be a sample path of a stochastic process with possible discontinuities. More precisely, signals will belong to the Skorohod space , i.e., the space of functions which are continuous on the right and have a left limit at all points (càdlàg functions). In particular, the space of continuous functions is a proper subspace of . Hence the response of a typical nonlinear operation that involves thresholding and switching can be modeled as a signal. The same goes for sample paths of counting processes and other martingales. A system is defined to be a measurable non-anticipatory map sending sample paths to sample paths so that their outputs at any time is a measurable function of past values of the input and time. For example, stochastic differential equations with Lipschitz coefficients driven by a Wiener process
induce maps between corresponding path spaces, see page 127 in Rogers and Williams, and pages 126-128 in Klebaner. Also, under fairly general conditions (see e.g., Chapter V in Protter), stochastic differential equations driven by martingales with sample paths in have strong solutions who are semi-martingales.
For the time setting , the feedback system can be written , where can be interpreted as an input.
Definition. A feedback loop is deterministically well-posed if it has a unique solution for all inputs and is a system.
This implies that the processes and define identical filtrations. Consequently, no new information is created by the loop. However, what we need is that for . This is ensured by the following lemma (Lemma 8 in Georgiou and Lindquist).
Key Lemma. If the feedback loop is deterministically well-posed, is a system, and is a linear system having a right inverse that is also a system, then is a system and for .
The condition on in this lemma is clearly satisfied in the standard linear stochastic system, for which , and hence . The remaining conditions are collected in the following definition.
Definition. A feedback law is deterministically well-posed for the system if is a system and the feedback system deterministically well-posed.
Examples of simple systems that are not deterministically well-posed are given in Remark 12 in Georgiou and Lindquist.
A separation principle for physically realizable control laws
By only considering feedback laws that are deterministically well-posed, all admissible control laws are physically realizable in the engineering sense that they induce a signal that travels through the feedback loop.
The proof of the following theorem can be found in Georgiou and Lindquist 2013.
Separation theorem.
Given the linear stochastic system
where is a vector-valued Wiener process, is a zero-mean Gaussian random vector independent of , consider the problem of minimizing the quadratic functional J(u) over the class of all deterministically well-posed feedback laws . Then the unique optimal control law is given by where is defined as above and is given by the Kalman filter. More generally, if is a square-integrable martingale and is an arbitrary zero mean random vector, , where , is the optimal control law provided it is deterministically well-posed.
In the general non-Gaussian case, which may involve counting processes, the Kalman filter needs to be replaced by a nonlinear filter.
A Separation principle for delay-differential systems
Stochastic control for time-delay systems were first studied in Lindquist,
and Brooks, although Brooks relies on the strong assumption that the observation is functionally independent of the control , thus avoiding the key question of feedback.
Consider the delay-differential system
where is now a (square-integrable) Gaussian (vector) martingale, and where and are of bounded variation in the first argument and continuous on the right in the second, is deterministic for , and .
More precisely, for , for , and the total variation of is bounded by an integrable function in the variable , and the same holds for .
We want to determine a control law which minimizes
where is a positive Stieltjes measure. The corresponding deterministic problem obtained by setting is given by
with .
The following separation principle for the delay system above can be found in Georgiou and Lindquist 2013 and generalizes the corresponding result in Lindquist 1973
Theorem. There is a unique feedback law in the class of deterministically well-posed control laws that minimizes , and it is given by
where is the deterministic control gain and is given by the linear (distributed) filter
where is the innovation process
and the gain is as defined in page 120 in Lindquist.
References
Control theory
Stochastic control | Separation principle in stochastic control | [
"Mathematics"
] | 2,812 | [
"Applied mathematics",
"Control theory",
"Dynamical systems"
] |
58,384,279 | https://en.wikipedia.org/wiki/Periodic%20short-interval%20diffuse%20discharges | Periodic short-interval diffuse discharges are a type of EEG abnormality with periodicity less than 4.0 seconds. They can consist of sharp waves or spikes, spike and wave, polyspikes or triphasics with background attenuation in between transients.
References
Electroencephalography
Neuroscience | Periodic short-interval diffuse discharges | [
"Biology"
] | 65 | [
"Neuroscience"
] |
58,387,667 | https://en.wikipedia.org/wiki/Multi-tip%20scanning%20tunneling%20microscopy | Multi-tip scanning tunneling microscopy (Multi-tip STM) extends scanning tunneling microscopy (STM) from imaging to dedicated electrical measurements at the nanoscale like a ″multimeter at the nanoscale″. In materials science, nanoscience, and nanotechnology, it is desirable to measure electrical properties at a particular position of the sample. For this purpose, multi-tip STMs in which several tips are operated independently have been developed. Apart from imaging the sample, the tips of a multi-tip STM are used to form contacts to the sample at desired locations and to perform local electrical measurements.
Introduction
As microelectronics evolves into nanoelectronics, it is essential to perform electronic transport measurements at nanoscale. The standard approach is to use lithographic methods to contact nanostructures, as it is also used in the final nanoelectronic device. In research and development stages, however, other methods to contact nanoelectronic devices or generally nanostructures may be more suitable. An alternative approach for contacting nanostructures uses the tips of a multi-tip scanning tunneling microscope—in analogy to the test leads of a multimeter used at macroscale. The advantages of this approach are: (a) in situ contacting of ″as grown″ nanostructures still under vacuum helps keep delicate nanostructures free from contamination induced by lithography steps performed for contacting. (b) Flexible positioning of the contacting tips and different contact configurations are easy to realize, while lithographic contacts are fixed. (c) Probing with sharp tips can be non-invasive (high ohmic), while lithographic contacts are typically invasive (low ohmic). To use a scanning tunneling microscope (STM) for electrical transport measurements at nanostructures or at surfaces, more than one tip is required. This motivates the use of multi-tip scanning tunneling microscopes which give access to the above outlined advantages in nanoprobing. Several review articles about multi-tip STM can be found in the further reading section below.
Principle of operation
Multi-tip scanning tunneling microscopes consist usually of four STM units positioning each of the tips individually to the desired position on the sample. To reduce thermal drift of the tips, the four STM units, should be as small and compact as possible. It is important that the motion of the tips can be observed, either by an optical microscope, or by a scanning electron microscope (SEM). This allows to bring the tips close together and to position them at the desired measurement locations. The tips in a multi tip STM are usually mounted under 45° relative to the vertical direction to facilitate positioning all tips at one region on the sample.
After the first multi-tip STM was introduced, several home-built instruments were designed and today, several commercial instruments are available as well.
An extension of the multi-tip STM technique is the upgrade to atomic force microscopy (AFM) operation. For applications in nanoelectronics, most of the samples consist of conducting "target" areas at the surface, separated by non-conducting areas. To guide the tip to the conducting areas, AFM imaging instead of or in addition to optical microscope or SEM guided positioning of the tips, can be very useful.
When performing electrical measurements on the nanoscale, it should be stressed that the contact resistance is often very large at the STM tip contact to the sample because the contact area is very small, so that four-point measurements are indispensable in resistance measurements with a muti-tip STM. This is even more important in measuring nano-scale objects, because the contacts to these objects are inevitably nano-scale. In a two-point resistance measurement, the two current injecting tips are used for voltage probing as well. Therefore, the measured resistance R = V/I also includes the contribution from the two contact resistances RC. In a four-point measurement the current injecting circuit is separated from the voltage sensing circuit. If the voltage measurement is performed with a large internal resistance RV, the influence of the contact resistances can be neglected. This is the main advantage of the four-point measurement.
Performing electrical measurements with a multi-tip STM demands more than four tips and the ability to position them as required. Concerted measurements of currents and voltages with all four tips must be performed. The electronics allows operating each tip either as (biased) current probe, or as voltage probe. Different I-V ramps are applied between different tips (and/or the sample). In the simplest case a current is injected between the two outer tips and a potential difference is measured between the inner tips (classical four-point measurement), also as a function of temperature.
However, also various kinds of other measurements can be performed, e.g., a tip or the sample can be used as gate electrode.
Applications of multi-tip STM
Graphene nanoribbons and graphene nanostructures
The local transport properties of 40 nm wide graphene nanoribbons grown on silicon carbide (SiC) substrates, are studied by means of a multi-tip STM. The graphene nanoribbons exhibit exceptional transport properties, such as ballistic conduction even at room temperature with mean free paths up to several μm. Such epitaxial graphene nanoribbons are important not only in fundamental science, but also because they can be readily produced in thousands in advanced nanoelectronics, which can make use of their room-temperature ballistic transport properties.
Resistance profiling along freestanding GaAs nanowires
The multi-tip STM can be used for resistance mapping along freestanding GaAs nanowires with a diameter of about 100 nm. The nanowires are still “as grown” upright and attached to the substrate, thus it is not possible to contact nanowires by lithographic techniques. In the measurement configuration shown in the figure, the sample is tilted by 45° to facilitate optimal SEM imaging of the nanowires. Three tips brought into contact with a nanowire realize a four-point resistance measurement (with the sample as fourth contact). Tip 1 injects the current to the nanowire with the sample acting as current drain, while tip 2 and tip 3 act as voltage probes. While it is relatively easy to study the structure of these nanowires e.g., with high resolution electron microscopy, it is difficult to access the electrical properties determined by the doping profile along the nanowire. From the measuremed four-point resistance along the nanowire a doping profile along the nanowire can be obtained.
Multi-tip potentiometry
A method giving valuable insight into the charge transport properties of nanostructures is the scanning tunneling potentiometry (STP). STP can be performed with a multi-tip STM and allows to map the potential landscape while a current flows through the film, nanostructure, or surface under study. Potentiometry maps give insight into fundamental transport properties, such as the influence of defects on the local electric transport. The implementation is shown in the figure, with the outer tips injecting a current into the nanostructure or surface being studied, while then
center tip simultaneously measures the topography and also records the electric potential at each image point which is induced by the flowing current. This way a potential map measured e.g. on a silicon surface can be acquired with a potential resolution is a couple of μV. The potential map in the figure shows that the largest potential drop occurs at the atomic step edges. From these data the resistance of a single atomic step, or a domain boundary can be obtained. Moreover, if a current flows around a nanoscale defect like. e.g.. a void, the potential map developing due to the flowing current can be measured.
Disentangling surface conductivity from bulk conductivity
As nano-devices become smaller and smaller, the surface to volume ratio (i.e., the fraction of atoms located at the surface) increases constantly. The increasing importance of surface conductance compared to conductance through the bulk in modern nanoelectronic devices calls for a reliable determination of the surface conductivity to minimize the influence of undesired leakage currents on the device performance or to use surfaces as functional units. A model system for corresponding investigations is the Si(111)-7×7 surface. The challenge is to disentangle the contribution due to the surface conductivity from the bulk conductivity. Using multi-tip STM, researchers developed a method that uses distance dependent four-probe measurements in the linear configuration to determine surface conductivity.
Spin current in quantum materials
Multi-tip STM is used as a method for the detection of the spin-voltage in topological insulators using spin-polarized four-probe scanning tunneling microscopy on Bi2Te2Se surfaces. The spin-dependent electrochemical potential is separated from the ohmic contribution. This component is identified as the spin-chemical potential arising from the 2D charge current through the spin momentum locked topological surface states (TSS). The new method uses a magnetic tip to observe the spin behavior of electrons on the material's surface.
See also
Scanning tunneling microscopy
Atomic force microscopy
Four-terminal sensing
Nanoprobing
Scanning electron microscope
References
Further reading
Microscopy | Multi-tip scanning tunneling microscopy | [
"Chemistry"
] | 1,946 | [
"Microscopy"
] |
58,388,186 | https://en.wikipedia.org/wiki/Korg%20Collection | The Korg Collection (initially launched as the Korg Legacy Collection in 2004) is a suite of virtual instruments and effects that emulate Korg's various hardware synthesizers. The original release included virtual versions of the MS-20, Polysix and Wavestation. Subsequent additions have expanded the collection to feature emulations of the Mono/Poly, M1, ARP Odyssey, Triton, miniKORG 700S, Prophecy and microKORG. These plugins utilize Korg's Component Modeling Technology (CMT) to simulate the analog characteristics of the original instruments. The collection is compatible with VST, AU, and AAX plugin formats and includes standalone versions for use outside a digital audio workstation (DAW).
History
Korg Legacy Collection (2004)
Launched in 2004, the initial Korg Legacy Collection featured emulations of the MS-20, Polysix, and Wavestation, along with a combination module named Legacy Cell, which integrates the MS20 and Polysix. The MS-20 plugin upgrades the original's monophonic capabilities to 32-voice polyphony, uses virtual patch cables and features MIDI-controllable knobs. The Polysix plug upgrades the original 6-voice polyphony to 32 voices, with added functionalities like MIDI clock synchronization for the LFO and arpeggiator. The Wavestation plugin offers sample rates from 44.1 kHz to 96 kHz, enhancing the original's 32 kHz rate, and comes with 550 presets. The original Legacy Collection also included MS-20iC, a USB controller designed for the MS-20 software that mirrors the appearance of the original MS-20, providing MIDI control and simulated patch cable manipulation.
Korg introduced the Legacy Collection Digital Edition in 2006, pairing the Wavestation plugin with a newly emulated Korg M1 plugin. The M1 plugin features 8-part multitimbrality, a maximum of 256-note polyphony, and includes presets from all 19 optional ROM cards. A free update added the entire preset collection from the T-series workstations to the M1 plugin.
Korg launched the Legacy Collection Analogue Edition in 2007, which combined the MS20 and Polysix plugins with a new emulation of the Mono/Poly. This new Mono/Poly plugin features eight virtual patches for enhanced modulation possibilities and increased polyphony of 128 voices.
Korg Collection (2017)
In December 2017, Korg renamed the Legacy Collection series to the Korg Collection and added an emulation of the Arp Odyssey, which followed the physical hardware reissue of the ARP Odyssey in 2015 with help from David Friend, co-founder of ARP Instruments.
Korg Collection 2 (2020)
In April 2020, Korg introduced the Collection 2, which provided updates to the previous plugins including scalable user interfaces and modern, high-definition graphics. These enhancements were provided free to existing users. The release also debuted an emulation of the Korg Triton, offering all 4,000 PCM-based presets, encompassing most sounds from Korg’s eight PCM Expansion boards. This version enhanced the polyphony to 256 voices but omitted the sampler, sequencer, and the capability to run a MOSS engine found in the original instrument.
Korg Collection 3 (2021)
In July 2021, Korg released the Korg Collection 3, adding three new software emulations to its lineup. This update featured an emulation of the miniKORG 700S, which added an arpeggiator, an eight-slot modulation matrix, and a six-effect virtual stompbox pedalboard. An emulation of the Prophecy upgraded the original monophonic limitation to support 256-voice polyphony and allowed for the import of Prophecy presets through sysex files. Additionally, a Korg Triton Extreme plugin was introduced, incorporating the valve amplifier effect from the original instrument.
Korg Collection 4 (2022)
The Korg Collection 4, launched in November 2022, featured a microKORG emulation that included the original's vocoder effect. This update also introduced a software effect named Electribe-R, inspired by iElectribe for iPad, but with enhanced beat modes and the integration of effects and step sequencing capabilities from the Electribe-R hardware and its mkII iteration. Additionally, a new Kaoss Pad effect was added, offering insights into its intricate internal architecture while maintaining the intuitive pad control interface.
Korg Collection 5 (2024)
On July 19th, 2024, Korg released the Korg Collection 5, expanding its software suite with three new additions: the ARP 2600, EP-1 electric piano, and Vox Super Continental organ. This latest update includes the semi-modular ARP 2600 synthesizer, renowned for its distinct sounds and now featuring both classic modifications and entirely new modules. The EP-1 electric piano engine introduces seven models previously part of the Nautilus series, while the Vox Super Continental offers a digital version of the combo organ. Notably, the ARP 2600 joins the ARP Odyssey in the collection, marking continued collaboration with ARP Instruments co-founder David Friend.
References
External links
KORG Collection
Software synthesizers
Audio software
Music technology
Korg | Korg Collection | [
"Engineering"
] | 1,091 | [
"Audio engineering",
"Audio software"
] |
58,388,209 | https://en.wikipedia.org/wiki/Gtel%20SL%205.5 | On 29 October 2014, GTel Zimbabwe launched the slimmest mobile phone handset in Africa and 2nd slimmest in the world in 2014, the Gtel SL 5.5 which is 5.60mm thin.
References
Mobile phones | Gtel SL 5.5 | [
"Technology"
] | 50 | [
"Mobile technology stubs",
"Mobile phone stubs"
] |
65,059,134 | https://en.wikipedia.org/wiki/Mercury%20%28crystallography%29 | Mercury is a freeware developed by the Cambridge Crystallographic Data Centre, originally designed as a crystal structure visualization tool. Mercury helps three dimensional visualization of crystal structure and assists in drawing and analysis of crystal packing and intermolecular interactions. Current version Mercury can read "cif", ".mol", ".mol2", ".pdb", ".res", ".sd" and ".xyz" types of files. Mercury has its own file format with filename extension ".mryx".
History
The Cambridge Crystallographic Data Centre (CCDC) developed and launched two programs, named ConQuest and Mercury that run under Windows and various types of Unix, including Linux. ConQuest as a search interface to the Cambridge Structural Database (CSD), with Fortran code that performs a large variety of tasks, such as two dimensional and three-dimensional substructure searching. Mercury introduced as a crystal structure visualizer having the facilities for exploring the intermolecular contacts. The mercury program entirely written in object oriented C++. The C++ Qt library is used for building the GUI and OpenGL for three-dimensional graphics rendering. The primary objective of the first generation Mercury is to provide the three dimensional viewing of crystal structures with .MOL2, .PDB, .CIF, .MOL file formats. The first version have approximately 2800 users signed on to the Mercury e-mail announcement list. Mercury 2.0 launched in 2008, with additional tools to interpret and compare packing trends in crystal structures. Mercury version released in 2015 and later provides an additional functionality to generate 3D print. The current Version 4.0 of Mercury developed its visual interface up to a greater extent by comparing with its old versions.
Licence
Mercury is available as a free download software and full version Mercury with more advanced features available with a CSD licence, advanced features are disabled in the absence of such a licence. Cambridge Crystallographic Data Centre (CCDC) provides CSD licence to academic institutions.
See also
Cambridge Crystallographic Data Centre
Crystallographic Information File
International Union of Crystallography
Protein Data Bank (file format)
CrystalExplorer
References
External links
Computational chemistry software | Mercury (crystallography) | [
"Chemistry"
] | 457 | [
"Computational chemistry",
"Computational chemistry software",
"Chemistry software"
] |
65,062,767 | https://en.wikipedia.org/wiki/Matthias%20L%C3%BCtolf | Matthias Lutolf (born in 1973, also known as Matthias Lütolf) is a bio-engineer and a professor at EPFL (École Polytechnique Fédérale de Lausanne) where he leads the Laboratory of Stem Cell Bioengineering. He is specialised in biomaterials, and in combining stem cell biology and engineering to develop improved organoid models. In 2021, he became the scientific director for Roche's Institute for Translation Bioengineering in Basel.
Career
Lutolf studied materials engineering at ETH Zurich where he graduated in 1998. In 2002, he received his PhD in biomedical engineering from ETH Zurich for his studies on cell-responsive hydrogels for tissue engineering and cell culture, in the group of Jeffrey Hubbell. He completed postdoctoral studies in the laboratory of Helen Blau at Stanford University, where he worked on novel cell culture approaches for blood and muscle stem cells, so called synthetic niches. In 2007, he founded his own laboratory at EPFL, where he was promoted to associate professor in 2014 and full professor in 2018. From 2014 to 2018, he was director of EPFL's Institute of Bioengineering. In June 2021, Lutolf became scientific director of the newly established Roche Institute for Translational Bioengineering in Basel, Switzerland.
Research
Lutolf's laboratory develops in vitro organoids mimicking healthy and diseased tissues and organs. Specifically, Lutolf uses bioengineering strategies to guide stem cell-based development to build novel organoids with improved reproducibility and physiological relevance for basic science and in vitro testing of drug candidates. His team has developed approaches to generate organoids in fully controllable 3D matrices, and has contributed to the understanding of how extrinsic biochemical and physical factors control stem cell fate and organogenesis. His team has developed concepts based on microfabrication, bioprinting, and microfluidics to improve the reproducibility, size, shape, and function of organoids.
Distinctions
In 2007, Lutolf received the European Young Investigator (EURYI) Award by the European Science Foundation. Since 2018, he is elected as member of the European Molecular Biology Organization (EMBO). He serves as associate editor of The Company of Biologists' journal Development.
Publications
External links
Website of the Laboratory of Stem Cell Bioengineering
References
Academic staff of the École Polytechnique Fédérale de Lausanne
ETH Zurich alumni
Stanford University people
21st-century Swiss biologists
Living people
1973 births
Bioengineers | Matthias Lütolf | [
"Engineering",
"Biology"
] | 521 | [
"Bioengineers",
"Biological engineering"
] |
65,063,436 | https://en.wikipedia.org/wiki/Feed%20ratio | A feed ratio is a measure of profitability of animal husbandry, expressed as the ratio between the cost of food and the price of the final product.
For example, in pig farming, the hog/corn ratio is the number of bushels of corn equal in value to 100 pounds of live hogs. Put another way, it is the price of hogs, per hundredweight, divided by the price of corn per bushel. Since corn is a major input cost to hog producers, the higher the price of hogs relative to corn, the more profit there is in feeding hogs.
In dairy farming, the milk-feed price ratio is a measure of the value of 16% protein ration to one pound of whole milk. As with the hog/corn ratio, this relationship is an indicator of the profitability of milk production.
See also
Pork cycle
References
Animal husbandry
Pig farming
Dairy farming
Financial ratios | Feed ratio | [
"Mathematics"
] | 186 | [
"Financial ratios",
"Quantity",
"Metrics"
] |
65,063,585 | https://en.wikipedia.org/wiki/Terraced%20wall | A terraced wall, also a terrace wall, or a terraced retaining wall is a wall that is divided into sections (terraces) over a slope. Such designs are useful when building on a steep grade. Terraced walls may be built with many different materials.
Some craters have terraced walls, which includes complex craters.
Types of terraced walls
A partially terraced wall is designed so that the upper terrace and lower terrace come back together, forming a taller wall. The wall may still work well, but may have aesthetic issues.
There are two types. In an independent terraced wall, the upper wall applies little or no weight load on the lower wall. In a dependent terraced wall, the upper wall places a weight load on the lower wall.
See also
Buttress
Buttress dam
Flying buttress
Load-bearing wall
Retaining wall
Terrace (building)
Terrace (earthworks)
Terrace garden
References
External links and references
Information on building a terraced garden
US government's NASA on a crater with a terraced wall
A youtube, on constructing a terrace wall
Another youtube
A youtube, on building rock walls for garden terraces
Types of wall | Terraced wall | [
"Engineering"
] | 229 | [
"Architecture stubs",
"Types of wall",
"Structural engineering",
"Architecture"
] |
65,064,571 | https://en.wikipedia.org/wiki/Shopping%20court | A shopping court is a type of neighborhood shopping center that developed, particularly in Greater Los Angeles, in the 1920s. Most had a few boutiques, themed shops (as today in a festival marketplace), and cafes, up to a dozen and sometimes included offices and studios. A linear walkway or patio connected the units, which was relatively new, as up to then, collections of shops under a management or coordination were connected by a public sidewalk, as in Westwood Village or Country Club Plaza. Patios of buildings in Mexico, Latin America and the Mediterranean inspired the design on the shopping court, as those regions also inspired much of the Southern California architecture during that era, e.g. Spanish Colonial Revival architecture. Shopping courts proliferated in the 1930s in affluent residential areas such as Hollywood, Beverly Hills, and Pasadena, and in resorts like Palm Springs and Santa Barbara. They were limited in impact as the scale could not accommodate larger stores and store windows did not draw attention of passing motorists.
Examples
Carmel-by-the-Sea – Carmel Plaza
Carthay Circle – Carthay Center (planned, mostly unbuilt
Downtown Los Angeles – Olvera Street (in form a pedestrian mall, but the selection of shops, restaurants and stands were selected as for a themed shopping court)
Fairfax District –
Farmers Market (not a true farmer's market)
Town & Country Market
Hollywood – Crossroads of the World
Southwest Los Angeles – Producer's Public Market
Santa Barbara – El Paseo
Ventura – La Floreira
In Mexico:
Pasaje Polanco in Mexico City, 1938; Colonial californiano style
References
Culture of Los Angeles
Architectural terminology
Shopping malls by type | Shopping court | [
"Engineering"
] | 334 | [
"Architectural terminology",
"Architecture"
] |
65,066,606 | https://en.wikipedia.org/wiki/Lydia%20Contreras | Lydia Contreras is a full professor at the University of Texas at Austin. She is an American chemical engineer most notable for her work on biomolecular engineering, genetics, and drug discovery.
Education
Contreras earned her B.S.E. in Chemical Engineering in 2003 from Princeton University and her Ph.D. in Chemical and Biomolecular Engineering in 2008 from Cornell University.
Academic career
Contreras is known for her experimental and computational work on understanding molecular features that lead to the interaction of RNAs and proteins. Her work has led to the development of new methods and understanding of, for instance, the capacity of RNA nucleotides to establish intermolecular RNA interactions via high-throughput characterization of RNA interfaces.
Following the completion of her PhD, she served as an NIH Postdoctoral Fellow in the Division of Genetics and Bioinformatics, Wadsworth Center at the New York State Department of Health from 2008 to 2010. She then served as a visiting Postdoctoral Fellow in the Department of Biochemistry at the Max F. Perutz Laboratories in Vienna before she began serving as an assistant professor at the University of Texas at Austin. In 2017, she was promoted to Associate Professor in the department of chemical engineering.
References
Living people
Year of birth missing (living people)
American chemical engineers
Chemical engineering academics
Women chemical engineers
21st-century American chemists
Dominican Republic emigrants to the United States
People from Santo Domingo
Cornell University College of Engineering alumni
Princeton University School of Engineering and Applied Science alumni
University of Texas at Austin faculty | Lydia Contreras | [
"Chemistry"
] | 310 | [
"Chemical engineering academics",
"Chemical engineers"
] |
65,068,961 | https://en.wikipedia.org/wiki/Temporary%20appropriation | Temporary appropriation refers to the action in which a person or a group of people realises an activity in a public space for which it was not designed for. According to Lara-Hernandez and Melis, it is process that implies dynamism similar to what Graumann called the humanisation of the space, which is the fundamental societal defined meanings interiorised by the individual. Representative activities of temporary appropriation can be grouped in three main categories: 1) sports, leisure and cultural activities; 2) activities related to economy such as work and services; and 3) activities related to sacralisation or worship. Authors stress two main factors that encourage the temporary appropriation phenomenon, on the one hand the cultural factor (also known as Synthetic psychological environment) while on the other the configuration or design of the built environment. The former refers to the group of symbols, values, attitudes, skills, knowledge, meanings, communication ways, social structure and physical objects that make possible the life of a determinate society. While the latter refers to human-made structures, features, and facilities viewed collectively as an environment in which people live and work. Temporary appropriation is an example of Architectural Exaptation in the urban environment.
Theoretical explanation
The term appropriation was firstly introduced by Korosec-Serfaty in the Proceedings of the Strasbourg conference in 1976. Within the field of environmental psychology, the term appropriation is described as a temporary phenomenon that implies a dynamic process of interaction between the individual and its surroundings. It is a process similar to that of humanisation. Since then, several authors such as Purcell, Pol, and Yory with the theory of topophilia, have used the term to explain the theoretical link between people and places. These authors consider the appropriation as an inborn necessity of humans that can be expressed through activities that occur in the urban landscape. Public spaces are an essential part of the urban landscape and their design is therefore strongly linked to the possibility of occurring activities related to the Temporary Appropriation. In other words, while appropriation is a broader term, its temporary variation refers more specifically to public spaces. The accent in the latter has always been placed on the informality of this action ( for more details see Temporary appropriation and urban informality: Exploring the subtle distinction). Dr. Lara-Hernandez conceptualises temporary appropriation instead as a consequence of the necessity of adapting human needs to a city that deprives the population of reference points due to sudden and unexpected changes. Additionally, it has been claimed that temporary appropriation plays a key role in enhancing urban resilience (see Temporary Appropriation in Cities: Human Spatialisation in Public Spaces and Community Resilience).
References
Public space
Urban design
Architecture | Temporary appropriation | [
"Engineering"
] | 551 | [
"Construction",
"Architecture"
] |
65,069,059 | https://en.wikipedia.org/wiki/WASP-35 | WASP-35 is a G-type main-sequence star about 660 light-years away. The star's age cannot be well constrained, but it is probably older than the Sun. WASP-35 is similar in concentration of heavy elements compared to the Sun.
The star has no detectable starspot activity. An imaging survey in 2015 found no detectable stellar companions, although a spectroscopic survey in 2016 yielded a suspected red dwarf companion with a temperature of .
Planetary system
In 2011 a transiting hot Jupiter planet b was detected. The planet's equilibrium temperature is .
References
Eridanus (constellation)
G-type main-sequence stars
Planetary systems with one confirmed planet
Planetary transit variables
J05041962-0613473
Durchmusterung objects | WASP-35 | [
"Astronomy"
] | 159 | [
"Eridanus (constellation)",
"Constellations"
] |
65,069,409 | https://en.wikipedia.org/wiki/Velmanase%20alfa | Velmanase alfa, sold under the brand name Lamzede, is a medication used for the treatment of alpha-mannosidosis. Velmanase alfa is a recombinant human lysosomal alpha-mannosidase.
The most common adverse reactions include hypersensitivity reactions including anaphylaxis, a severe, potentially life-threatening allergic reaction.
Velmanase alfa was approved for medical use in the European Union in March 2018, and in the United States in February 2023. Velmanase alfa is the first enzyme replacement therapy approved in the US for the treatment of the non-central nervous system manifestations of alpha-mannosidosis. The US Food and Drug Administration (FDA) considers it to be a first-in-class medication.
Medical uses
Velmanase alfa is indicated for the treatment of the non-central nervous system manifestations of alpha-mannosidosis.
Alpha-mannosidosis is a rare genetic lysosomal storage disorder. The symptoms of the disorder vary, but often include mild to moderate intellectual disability, hearing loss, weakened immune system, distinctive facial features (e.g., a large head, prominent forehead, and protruding jaw), skeletal abnormalities, and muscle weakness. Alpha-mannosidosis is caused by genetic changes in the MAN2B1 gene, which codes for the lysosomal alpha-mannosidase enzyme. Mutations of the MAN2B1 gene result in the lack of production of the alpha-D-mannosidase enzyme or the production of a defective, inactive form of the enzyme. Alpha-mannosidosis affects about 1 in every 500,000 people worldwide.
History
The effectiveness of velmanase alfa was evaluated in participants with alpha-mannosidosis in a phase III multicenter, randomized, double-blind, placebo-controlled, parallel group study. The trial evaluated the efficacy of velmanase alfa over 52 weeks at a dose of 1 mg/kg given weekly as an intravenous infusion. A total of 25 participants were enrolled (14 males, 11 females), including 13 adult participants (age range: ≥18 to 35 years; mean: 25 years) and 12 pediatric participants (age range: ≥6 to <18 years; mean: 11 years); all participants were White. Fifteen participants (8 adult and 7 pediatric) received velmanase alfa and 10 participants (5 adult and 5 pediatric) received placebo.
Society and culture
Names
Velmanase alfa is the international nonproprietary name.
References
External links
Orphan drugs
Recombinant proteins | Velmanase alfa | [
"Biology"
] | 536 | [
"Recombinant proteins",
"Biotechnology products"
] |
65,069,448 | https://en.wikipedia.org/wiki/GSC%2003949-00967 | GSC 03949-00967 is a G-type main-sequence star about 1179 light-years away. It is older than the Sun, yet is enriched by heavy elements compared to the Sun, having 160% of solar abundance.
Planetary system
TrES-5b
In 2011 a transiting hot Jupiter planet TrES-5b was detected. The host star was one of the faintest stars to which a planetary companion was detected by the transit method at the time of discovery. The planet’s equilibrium temperature is .
TrES-5c/TrES-5B
An additional planet on a 4-day orbit in the system was suspected since 2018, but refuted in 2021. Another object on a wide orbit, either star or planet, is still suspected.
References
Cygnus (constellation)
G-type main-sequence stars
Planetary systems with one confirmed planet
Planetary transit variables
J20205324+5926556 | GSC 03949-00967 | [
"Astronomy"
] | 191 | [
"Cygnus (constellation)",
"Constellations"
] |
65,069,987 | https://en.wikipedia.org/wiki/Xiao%20Guangyan | Xiaoguang Yan (, sometimes written as Xiaoguang Yan or Xiao Guang Yan, – ) was a Chinese petrochemist who researched catalysts used in petroleum processing. He was born in Japan to Chinese parents. When he was young, he moved to the United States to study and work, earning a B.A. in chemistry from Pomona College in 1942 after transferring from Pasadena City College in 1940, and later a Ph.D. from the University of Chicago. He returned to China in 1951 after the establishment of the People's Republic of China. He became one of the pioneers of petrochemical research in the PRC, researching various catalysts for hydrocracking, hydroisomerization, and other petroleum processing techniques. He fell out of favor during the Cultural Revolution and committed suicide in 1968 along with his wife and daughter, but was posthumously rehabilitated in 1972.
Biography
Early life and US years
Xiao Guangyan was born in Tokyo Prefecture, Great Japanese Empire, September 15, 1920. His father was Xiao Quanxuan, a military attache at the Embassy of the Republic of China in Japan, and later served as minister in the Wang Jingwei regime. Xiao Guangyan studied at Shanghai Nanyang Model Middle and Primary School from 1928 to 1937, and in February 1937 moved to the United States. Xiao Guangyan entered the Pasadena City College, completed high school in 1938, and completed the freshman and sophomore courses with honors in 1940; he entered the Chemistry Department of Pomona College in 1940, and graduated as a senior in 1942. In the fall of the same year, he became a graduate student in the Department of Chemistry at the University of Chicago, studying for a Ph.D. under James Franck. During this period, he served as a teaching assistant in organic chemistry, physical chemistry and advanced physical chemistry courses. He received a doctorate in physical chemistry in March 1946.
After graduation, Xiao Guangyan was employed as an assistant researcher in the Department of Chemistry at the University of Chicago from January 1946 to August 1946. From September 1946 to October 1950, he was a researcher at the Metallurgical Laboratory of the University of Chicago. During November, he worked in the basic research catalysis group of Mobil.
While in US Xiao Guangyan participated in the North American Chinese Student Christian Association and other student club activities. The club gatherings were often held at his home. Through these activities he was exposed to Marxism-Leninism and other ideas, and he was increasingly yearning for the newly established People's Republic of China. In addition, at that time Chinese overseas students discussed whether to return to China and participate in the construction of the new China. Xiao Guangyan was acquainted with some students who returned to China, who influenced him to take the same decision. The US immigration officials tried to retain Xiaoguang Yan, explaining that they would complete the formalities for him to live in US within two to three months, but he refused to stay.
Relocation to China
Therefore, in 1950 Xiao Guangyan traveled to China as a literature student at the University of Chicago (not as a PhD, so as not to be obstructed by the Immigration Bureau). He set off in November 1950 and boarded the President Wilson cruise in Los Angeles, USA, passing through Honolulu and Manila, in late December he arrived to Hong Kong, and to Beijing in March 1951.
Once in China, Xiao Guangyan was assigned to work in the Ministry of Petroleum Industry of the People's Republic of China. After living in Beijing for some time, Xiao Guangyan moved to Dalian and worked in the Dalian branch of the Northeast Institute of Science (Dalian Institute of Chemical Physics). After the outbreak of the Korean War, the Chinese society began to distrust of intellectuals who had returned from the United States; with the development of the ideological reform movement in 1951, and people started to reject Xiao Guangyan, and later questioned his motives for returning to China, and was criticized for talking about his previous life in the United States, and for "worshiping foreigners and wooing foreigners". Facing criticism, Xiaoguang Yan developed a strong sense of anger. Xiaoguang Yan was anxious, experiencing mood swings, some days he would miss work to protest, and on occasions took large doses of sleeping pills. After the ideological reform movement ended, Xiao Guangyan's life calmed down, and the leader of the institute apologized to him for his unfounded suspicion, and Xiao worked hard to resume work regardless of previous suspicions.
In early 1956, the Beijing Petroleum Refining Research Institute was established and Xiao Guangyan was invited to work here; he came to Beijing to experience the working environment for a while, and finally thought that Dalian had more basic research and the environment was more suitable for him, so he decided to refuse the invitation. While the practice of choosing a more ideal job is common in the United States, the Chinese society at that time pursued the idea of strictly obeying superiors, which made Xiao Guangyan once again been questioned. In 1957, Mao Zedong launched the "Da Ming Da Fang" Hundred Flowers Campaign (encouraging citizens to express openly their opinions of the communist regime), Xiaoguang Yan then submitted an article to the Chinese Communist Party Committee Secretary, criticizing the attitude of people to question their own thinking during the reform movement; but suddenly Da Ming Da Fang turned into an anti-rightist movement. Although some intellectuals who had previously expressed opinions were classified as rightists and punished, Xiao Guangyan was not classified as rightists. In 1958, Xiao Guangyan's Catalytic Process Laboratory planned to move to Lanzhou, Gansu, but he asked to stay in Dalian, which has better scientific research conditions, and the request was approved by the research institute. However, this request violated the mainstream values of the Chinese society at that time.
In the Great Leap Forward period of "pulling out the white flags and planting the red ones in their stead" campaign, once again Xiaoguang Yan faced criticism. People questioned his motives for returning to China, work attitude, and living habits, and attacked him for being "demanding", "pampering with dignity", "greedy", "school lords", and "profiteer", big-character posters with these contents appeared everywhere. In the New Year, people performed live newspaper dramas that insulted Xiao Guangyan at the New Year's party, portraying him as a clown, and mocking his words and deeds. In this regard, Xiao Guangyan was extremely angry and became silent and distressed; he gradually lost himself after a long period of political criticism, and he did not dare to express his opinions directly as before. Later, people stopped criticizing scientific researchers, and the leaders of the institute apologized to Xiao Guangyan himself in 1961, and he resumed his work regardless of previous suspicions.
Persecution and suicide
During the movement to purify the class ranks during the Cultural Revolution, Xiao Guangyan was pinpointed as a "counter-revolutionary agent", and denounced and criticized through posters, and was forced to move to different neighbourhood. On October 5, 1968, Xiao Guangyan was ransacked by the Workers' Propaganda Team and imprisoned in a bullpen (a place where intellectuals were detained during the Cultural Revolution). He was desperate. The Workers Propaganda Team referred to Xiao Guangyan as a member of the secret service agency, and people joined in attacking Xiao Guangyan. He was interrogated with perseverance, using force methods such as punches, kicks, and torture to extract confessions, and was requested to continue to write confessions and expose his crimes. On the morning of December 11, 1968, Xiao Guangyan was found dead. The autopsy revealed that he committed suicide by taking barbital.
Personal life
Xiao Guangyan married Zhen Suhui in 1945. Zhen Suhui was born and raised in the United States and didn't speak Chinese. Her father used to be Sun Yat-sen's secretary. Later, he was sent by the Nationalist Government to work as an expatriate in the United States.
Zhen Suhui initially resisted Guanyan's plans for moving to China due to the language barrier and the political situation there. However, Xiao Guangyan had decided, and even proposed to go to China alone and let Zhen Suhui stay in the United States; she finally gave in and accompanied her husband to China. She served as English teacher at Dalian Maritime University. When Xiao Guangyan was troubled by political struggles, Zhen Suhui provided him understanding and comfort. The couple gave birth to their daughter in 1952, Xiao Luo Lin (nickname "Lolo").
During the Cultural Revolution, Zhen Suhui accepted to do labor work at Dalian Yingchengzi Farm, while Xiao Luolian was left alone at home. After Xiao Guangyan committed suicide, the work propaganda team called Zhen Suhui to Dahua Office to notify her of the death of her husband; she reacted calmly and asked the work propaganda team to give her two days off to take care of her daughter. On December 13, 1968, Zhen Suhui and Xiao Luolian took barbital together and died hugging each other in bed at home.
Rehabilitation
After Xiao Guangyan's death, he was accused of being the central figure of the "301 Special Agent Group". His death triggered the "301" case, which was a major case and was later regarded as a model of "working class occupation of scientific research department". The work propaganda team described Xiao Guangyan's death as "the choice when class enemies are desperate" and "the great victory of the dictatorship of the proletariat ", and announced it as "extraordinarily good news" to inform all members of the Chinese Academy of Sciences, and classified him as a "counter-revolutionary agent".
Xiao Guangyan's former friend Bai Jiefu indicated that the prime minister Zhou Enlai personally asked to be informed about Xiao Guangyan's death and pursued those involved. In the end, two members of the work propaganda team (one was the leader and the other was the principal offender of the beating of Xiao Guangyan) were punished.
In August 1972, Xiao Guangyan's former friend and McGill University professor Lin Daguang visited China and was received by Zhou Enlai. During the period, he mentioned to Zhou Xiao's experience during the Cultural Revolution. Zhou Enlai said at the time that if it is found that Xiao Guangyan was indeed wronged, he should be rehabilitated. On September 9, 1972, the Chinese Communist Party Committee of the Dalian Institute of Chemical Physics of the Chinese Academy of Sciences published the "Examination Conclusions on Xiao Guangyan's Historical Issues", denying the accusations against Xiao Guangyan of being a "secret agent" during the Cultural Revolution, defining these accusations as false, and concluding that his return to China was out Yu's patriotic behavior, praised him for his love of the Chinese Communist Party and the socialist system, and affirmed that he made certain contributions to the country during his lifetime. On March 11, 1978, a memorial service for Xiao Guangyan was held in the auditorium of the Dalian Institute of Chemical Physics. The director of the institute said in his memorial speech: "Comrade Xiao Guangyan loves Chairman Mao, loves the Communist Party, and loves socialism. He has made contributions and is a talented person. The death of Comrade Xiao Guangyan was a major loss to the scientific research work of the Institute." Since then, Xiao Guangyan has been completely rehabilitated in the People's Republic of China.
Notes
References
People from Fuzhou
Chemists from Fujian
University of Chicago alumni
Pomona College alumni
Chemical engineering academics
ExxonMobil people | Xiao Guangyan | [
"Chemistry"
] | 2,431 | [
"Chemical engineering academics",
"Chemical engineers"
] |
65,071,138 | https://en.wikipedia.org/wiki/Neuropixels | Neuropixels probes (or "Neuropixels") are electrodes developed in 2017 to record the activity of hundreds of neurons in the brain. The probes are based on CMOS technology and have 1,000 recording sites arranged in two rows on a thin, 1-cm long shank.
The probes are used in hundreds of neuroscience laboratories including the International Brain Laboratory, to record brain activity mostly in mice and rats. By revealing the activity of vast numbers of neurons, Neuropixels probes are allowing new approaches to the study of brain processes such as sensory processing, decision making, internal state, and emotions and to create brain-machine interfaces.
The probes were announced in 2017. They are designed and fabricated by imec, an electronics research center in Belgium. In 2022, Neuropixels probes were inserted in human patients.
References
External links
UCL Neuropixels page
neuropixels.org
SpikeGLX: Neuropixels acquisition software
Open Ephys GUI: Neuropixels acquisition software
Neuropixels slack channel
Neuroscience
Neural engineering | Neuropixels | [
"Biology"
] | 235 | [
"Neuroscience"
] |
65,071,349 | https://en.wikipedia.org/wiki/4-Vinylanisole | 4-Vinylanisole is an organic compound with the formula CH3OC6H4CH=CH2. It is one of three isomers of vinylanisole. A colorless liquid, 4-vinylanisole is found in a number of foods and drinks. It is also a monomer for the synthesis of modified polystyrenes. It is an aggregation pheromone used by locusts.
References
Pheromones
4-Methoxyphenyl compounds
Allyl compounds | 4-Vinylanisole | [
"Chemistry"
] | 106 | [
"Pheromones",
"Chemical ecology"
] |
65,071,929 | https://en.wikipedia.org/wiki/Hydrocinnamaldehyde | Hydrocinnamaldehyde is the organic compound with the formula C6H5CH2CH2CHO. It is produced by the hydrogenation of cinnamaldehyde. The compound is used in many mechanistic studies. It is a common substrate in organic synthesis.
References
Phenylpropanoids | Hydrocinnamaldehyde | [
"Chemistry"
] | 66 | [
"Biomolecules by chemical classification",
"Phenylpropanoids"
] |
65,072,138 | https://en.wikipedia.org/wiki/Asus%20ZenFone%207 | The ZenFone 7 and ZenFone 7 Pro are Android-based smartphones manufactured, released and marketed by Asus. The phones were unveiled on 26 August 2020, and succeed the ZenFone 6.
Introduction
On 26 August 2020, Asus launched the ZenFone 7 series in a Mandarin online press conference from their Taiwan headquarters. The ZenFone 7 series consists of the ZenFone 7 and ZenFone 7 Pro, retaining the hallmark flip-up camera form factor of the ZenFone 6 with the addition of a 3x telephoto camera, Sony IMX686 main sensor, 8K video recording capabilities, improved actuation mechanism, and optical image stabilisation exclusive to the Pro model. The ZenFone 7 series features a 6.67-inch 90 Hz AMOLED display with 200 Hz touch sampling and a 5G-capable Snapdragon 865 system on a chip, with the higher-clocked Snapdragon 865 Plus on the Pro model. Other changes include the removal of the headphone jack, ZenUI 7, 30W fast charging, combined side-mounted fingerprint scanner–power button–smart key, UFS 3.1 storage, three-microphone array utilising Nokia’s OZO Audio processing, and a larger and heavier overall form factor. The ZenFone 7 and 7 Pro are priced starting at and , respectively. The ZenFone 7 series will not be available in North America because of a lack of 5G band support.
References
External links
Mobile phones introduced in 2020
Mobile phones with multiple rear cameras
Mobile phones with 8K video recording
Asus ZenFone
Discontinued flagship smartphones | Asus ZenFone 7 | [
"Technology"
] | 341 | [
"Mobile technology stubs",
"Discontinued flagship smartphones",
"Flagship smartphones",
"Mobile phone stubs"
] |
75,063,524 | https://en.wikipedia.org/wiki/Bromal%20hydrate | Bromal hydrate is an organobromine compound with the chemical formula . It is the bromine analogue of chloral hydrate. Bromal hydrate forms when bromal is reacted with water. It decomposes to bromal and water upon distillation. It has hypnotic and analgesic properties but acts like a stimulant at lower doses. Bromal hydrate is more physiologically active than its chlorine analogue, chloral hydrate. Its direct effect on the heart muscles is stronger than that of chloral hydrate. Its analgesic effects were attributed to the proposed metabolism to bromoform.
It was also tried as a medication for epilepsy, but was found ineffective.
References
Hydrates
Hypnotics
Geminal diols
Organobromides | Bromal hydrate | [
"Chemistry",
"Biology"
] | 164 | [
"Hypnotics",
"Behavior",
"Sleep",
"Hydrates"
] |
75,064,357 | https://en.wikipedia.org/wiki/Tris%28bipyridine%29iron%28II%29%20chloride | Tris(bipyridine)iron(II) chloride is the chloride salt of the coordination complex tris(bipyridine)iron(II), . It is a red solid. In contrast to tris(bipyridine)ruthenium(II), this iron complex is not a useful photosensitizer because its excited states relax too rapidly, a consequence of the primogenic effect.
Tris(bipyridine)iron(II) chloride features an octahedral Fe(II) center bound to three 2,2'-Bipyridine ligands. The complex has been isolated as salts with many anions.
Synthesis and reactions
The sulfate salt is produced by combining ferrous sulfate with excess bipy in aqueous solution. This result illustrates the preference of Fe(II) for bipyridine vs water. Addition of cyanide to this solution precipitates solid .
Related complexes
Tris(o-phenanthroline)iron(II)
Reference
Iron complexes
Bipyridine complexes
Iron(II) compounds
Chlorides | Tris(bipyridine)iron(II) chloride | [
"Chemistry"
] | 229 | [
"Chlorides",
"Inorganic compounds",
"Salts"
] |
75,065,896 | https://en.wikipedia.org/wiki/Visible%20difference | A visible difference refers to a physical characteristic, such as a scar, mark, disfigurement, or condition on the face or body that distinguishes an individual from what is conventionally considered to be the societal norm. These visible differences can arise due to a multitude of factors including but not limited to congenital conditions, accidents, diseases, or surgical procedures. Such differences often carry significant psychological, social, and sometimes physical implications for the affected individual.
Terminology
While the terms visible difference and disfigurement are sometimes used interchangeably, they are not synonymous and possess distinct connotations both in medical and social contexts.
The term visible difference is a more neutral, encompassing descriptor for any physical characteristic that sets an individual apart from what is generally considered the societal norm. This could be due to congenital conditions, acquired conditions, diseases, or even personal choices like tattoos or piercings. The critical element is that the difference is visible, but the term does not inherently imply any impairment, disadvantage, or negative valuation.
Disfigurement is a term that has traditionally been used in both legal and medical contexts to refer to physical alterations that are often perceived as impairing the appearance of an individual in a significant way. Disfigurement generally carries a more negative connotation and often implies a level of severity or permanence to the condition that may result in social, emotional, or functional difficulties for the affected individual.
Background and history
Early perceptions
The concept of visible differences has existed throughout human history, although the terminology and social attitudes have evolved. In many ancient cultures, visible differences were often attributed to supernatural causes or seen as a sign of divine intervention. For example, birthmarks were sometimes viewed as omens or indicators of future events, both positive and negative.
Modern medicine
With the advent of modern medicine, understanding the causes behind various types of visible differences has become more scientific. In the 19th and early 20th centuries, significant strides were made in dermatology and plastic surgery, which allowed for a more nuanced comprehension and treatment of these conditions. The latter half of the 20th century saw further research into the psychological and emotional impact of visible differences, paralleling the rise of psychology as a distinct scientific discipline.
Activism and milestones
The latter part of the 20th century also saw the rise of activism aimed at destigmatizing visible differences and advocating for legal protections. Landmark legislation, such as the Americans with Disabilities Act (ADA) in the United States and the Equality Act in the United Kingdom, have created legal protections for people with visible differences.
Changing Faces is a UK-based organization that advocates for people living with visible differences.
Types of visible differences
Visible differences can be categorized based on origin, location, and impact.
Congenital conditions
These are visible differences present from birth and are often the result of genetic factors or prenatal influences.
Birthmark: Size, shape, and color can vary.
Cleft lip or palate: A condition with an opening in the upper lip and/or palate.
Port-wine stain: Reddish or purplish marks that usually occur on the face.
Acquired conditions
These visible differences arise due to external factors, such as accidents or medical treatments.
Scar: Can result from injuries, surgeries, or severe acne.
Vitiligo: This condition causes patches of skin to lose their pigment.
Burn: Severe burns can lead to scarring and discoloration of the skin.
Amputation: Removal of a limb, often due to injury or infection.
Diseases
Certain diseases can cause visible differences either directly or as a side effect of treatment.
Acne: Often associated with adolescence but can persist into adulthood, leading to scarring or pigmentation.
Psoriasis: Characterized by red, scaly patches on the skin.
Autoimmune disease: Diseases like lupus can cause visible skin rashes or facial flushing.
Alopecia areata: Leads to hair loss, commonly on the scalp.
Psychological impact
The presence of a visible difference can have profound psychological implications for an individual, affecting their self-esteem, mental health, and overall well-being. Importantly, research has indicated that there is not a strong correlation between the visibility or severity of the physical characteristic and the level of psychological distress an individual might experience. This counterintuitive finding emphasizes the complexity of the emotional and psychological dimensions involved.
Self-esteem and body image
People with a visible difference often face self-esteem and body image challenges. Concerns about appearance can dominate their self-perception, which may lead to feelings of inadequacy or unattractiveness. This can be particularly challenging during adolescence when physical appearance is often highly emphasized.
Anxiety and depression
Studies have shown that individuals with visible differences are at a higher risk of developing anxiety disorders and depression. The constant awareness of being different and the fear of being judged or rejected can increase anxiety levels. Similarly, chronic feelings of isolation or stigmatization can lead to depressive symptoms.
Social isolation
The social implications of having a visible difference can sometimes lead to withdrawal or isolation. Avoidance behavior, such as skipping social events or avoiding public places, can exacerbate feelings of loneliness and perpetuate a cycle of emotional distress.
Body dysmorphic disorder
In some cases, individuals with a visible difference may develop body dysmorphic disorder, a mental health condition characterized by obsessive focus on perceived flaws in physical appearance. Importantly, these perceived flaws may be minor and not very noticeable to others.
Coping mechanisms
Individuals may employ various coping mechanisms, both adaptive and maladaptive, to deal with the psychological impact. While some may resort to avoidance or denial, others may seek social support or engage in constructive problem-solving.
Visibility and distress
Contrary to common assumptions, the psychological distress associated with having a visible difference does not necessarily correlate with the visibility or severity of the condition. Factors such as personal resilience, availability of social support, and pre-existing mental health conditions often play a more significant role in determining the level of psychological impact.
See also
Changing Faces (charity)
References
Human appearance
Human body | Visible difference | [
"Physics"
] | 1,227 | [
"Human body",
"Physical objects",
"Matter"
] |
75,065,921 | https://en.wikipedia.org/wiki/Emergent%20Universe | An emergent Universe scenario is a cosmological model that features the Universe being in a low-entropy "dormant" state before the Big Bang or the beginning of the cosmic inflation. Several such scenarios have been proposed in the literature.
"Cosmic egg" scenarios
A popular version proposed by George Ellis and others involves the Universe shaped like a 3-dimensional sphere (or another compact manifold) until a rolling scalar field begins inflating it. These models are notable as potentially avoiding both a Big Bang singularity and a quantum gravity era.
Criticism
This proposal has been criticised by Vilenkin and Mithani and on different grounds by Aguirre and Kehayias as inconsistent if quantum-mechanical effects are taken into account.
References
Physical cosmology | Emergent Universe | [
"Physics",
"Astronomy"
] | 152 | [
"Astrophysics",
"Theoretical physics",
"Physical cosmology",
"Astronomical sub-disciplines"
] |
75,067,461 | https://en.wikipedia.org/wiki/Alfred%20J.%20Stamm | Alfred J. Stamm (1897–1985) was an American chemist and pioneering wood scientist, who worked at the Forest Products Laboratory and was a honorary fellow of the International Academy of Wood Science. His research contributions in the chemical modification of wood (acetylation, furfurylation, etc.) have been well recorded in the literature and gained a global attention in the scientific area of wood science.
Stamm attained his PhD degree in the field of physical chemistry from the University of Wisconsin. Following a long and fruitful 34-year tenure at the Forest Products Laboratory in Madison, Wisconsin, Stamm assumed a position at the School of Forestry at North Carolina State University in 1959, where he dedicated his efforts to both pedagogy and scholarly research until his retirement in 1970.
During his career, Stamm authored numerous publications on the subjects of wood physics and chemistry, and his contributions earned him several awards in recognition of his scholarly achievements. He has had almost 12,000 citations for his research works at Google Scholar, as of June 2024.
References
External links
Google Scholar
1897 births
1985 deaths
20th-century American scientists
Wood sciences
Wood scientists
Fellows of the International Academy of Wood Science | Alfred J. Stamm | [
"Materials_science",
"Engineering"
] | 243 | [
"Wood sciences",
"Wood scientists",
"Materials science"
] |
75,068,099 | https://en.wikipedia.org/wiki/Dolly%20pot | A dolly pot, also known as a dolly, is a portable tool used for crushing small quantities of gold-bearing rock, by hand, in a process known as dollying.
In principle, a dolly pot is somewhat like a large mortar and pestle, but is always made of metal and is intended specifically to crush hard rocks like quartz. It is typically flat at the bottom, rather than rounded as in a typical mortar. 19th-century versions were often made of cast iron. Modern dolly pots are typically fabricated from steel. The place of the pestle is taken by a long heavy steel rod, at one end provided with a stamping surface.
The process of dollying is highly labour-intensive. It involves pulverising the rock, by hand, until the gold separates from the surrounding rock matrix. It typically is used only to test for the presence of gold in samples taken from a quartz reef.
References
Gold prospecting | Dolly pot | [
"Physics"
] | 189 | [
"Metallic objects",
"Physical objects",
"Matter"
] |
75,068,654 | https://en.wikipedia.org/wiki/Cryptomator | Cryptomator is open source encryption software that provides encryption for cloud drives. It provides transparent, client-side encryption for personal cloud storage. Cryptomator encrypts each file separately and then allows the user to sync files with a cloud or local storage of choice. It is available for all major operating system including Android, iOS, Windows, Mac, Linux.
Cryptomator uses AES-256 standard encryption and WebDAV and relies on its open-source model for software verifiability, trust and bug fixing. The software encrypts each file individually.
History
In 2017, Cure53 audited the software. Cryptomator was lauded for its high degree of robustness in cryptographic implementation, but criticized use of AES in insecure ECB mode. Tobias Hagemann, however, said this was a false positive. "This is due to the Java Cryptography Extension, where the ECB mode must be specified for the creation of the SIV mode, even though this is and was never used by Cryptomator."
In December 2021, Cryptomator 2.0 was released for iOS, which was rewritten in Swift and integrated with the native iOS Files app.
In January 2022, an update was released for a bug that leaked file path to Apple, because of the integration with Apple's file and use of File Provider Extension API.
Reception
Cryptomator received the CeBIT innovation award in 2016 for "Usable Security and Privacy".
References
External links
Cryptomator Community
Cryptographic software
Free and open-source software
Java platform software
Software using the GNU General Public License
Free software programmed in Java (programming language) | Cryptomator | [
"Mathematics"
] | 337 | [
"Cryptographic software",
"Mathematical software"
] |
75,068,957 | https://en.wikipedia.org/wiki/282%20%28number%29 | 282 (two hundred [and] eighty-two) is the natural number following 281 and preceding 283.
In mathematics
282 is an even composite number with three prime factors.
282 is a palindromic number. This is a number that is the same backwards as it is forwards. 282 is the smallest multi-digit palindromic number that is between twin primes, numbers that are prime and are 2 away from another prime number.
282 is equal to the sum of its divisors containing the number 4. It is the sum of 47 + 94 + 141.
282 is the number of planar partitions of 9. This means that 282 is the number of ways to separate 9 units.
References
Integers | 282 (number) | [
"Mathematics"
] | 146 | [
"Elementary mathematics",
"Integers",
"Mathematical objects",
"Numbers"
] |
75,073,083 | https://en.wikipedia.org/wiki/Psychological%20barriers%20to%20effective%20altruism | In the philosophy of effective altruism, an altruistic act such as charitable giving is considered more effective, or cost-effective, if it uses a set of resources to do more good per unit of resource than other options, with the goal of trying to do the most good. In a book written by effective altruism scholars Stefan Schubert and Lucius Caviola, the effectiveness of helping is defined by how many lives you save or how much good you otherwise do with a given amount of resources.
Following this definition of effectiveness, researchers in psychology and related fields have identified psychological barriers to effective altruism that can cause people to choose less effective options when they engage in altruistic activities such as charitable giving. These barriers can include evolutionary influences as well as motivational and epistemic obstacles.
Overview
In general, humans are motivated to do good things in the world, whether that is through donations to charity, volunteering time for a cause, or just lending a hand to someone who needs help. In 2022, approximately 4.2 billion people donated their money, time, or helped a stranger. Donating money to charity is especially substantial. For instance, 2% of the GDP of the United States goes to charitable organizations—a total of more than $450 billion in annual donations. Despite the human tendency and motivation to give and engage in altruistic behavior, research has shed light on an unequal motivation to give effectively.
Humans are motivated to give, but often not motivated to give most effectively. In the title of an article published in Nature Human Behaviour in 2020, Bethany Burum, Martin Nowak, and Moshe Hoffman termed this phenomenon , that is, relatively less sensitivity to cost-effectiveness in altruistic behaviour. In the domain of business decisions, investors look for how much return they will get for each dollar they invest. However, when it comes to the domain of altruistic decision-making, this line of thinking is far less common. Most donors seem to prioritize giving to charitable organizations that spend the least possible amount on running costs in the hopes of having more of their donation reach the destination.
Evolutionary explanations
While plenty of studies in the behavioral sciences have demonstrated the cognitive and emotional limitations in charitable giving, some argue that the reasons behind ineffective giving run deeper. A study by Martin Nowak and fellow academics at Harvard University and the Massachusetts Institute of Technology suggested that the human tendency to ineffective altruism can be explained through evolutionary motives and evolutionary game theory. They argue that society rewards the act of giving but generally provides no motivation or incentive to give effectively. Past research suggests that altruistic motives are distorted by, among other things, parochialism, status seeking and conformity.
Parochialism
People are sensitive to effectiveness when they or their kin are at stake, but not so much when confronted with a needy stranger. Donors have been shown to respond to impact and efficacy when giving to themselves, but less so when donating to charity. While cost-effectiveness information of charities tends to be hard to evaluate, studies have shown that people are less scope insensitive when the beneficiaries are family members.
Throughout human evolutionary history, residing in small, tightly-knit groups has given rise to prosocial emotions and intentions towards kin and ingroup members, rather than universally extending to those outside the group boundaries. Humans tend to exhibit parochial tendencies, showing concern for their in-groups, but not out-groups. This parochial inclination can hinder effective altruism, especially as a significant portion of human suffering occurs in distant regions. Despite the potential impact of donations in different parts of the world, individuals in rich and developed countries often view assistance to physically distant others as less important than helping those in close proximity. Contrary to maximizing impact and effectiveness with their donations, many individuals commit to donating money to local charities and organizations to which they have a personal connection, thus living by the notion of "charity begins at home." Similarly, people are more inclined to help a needy child from their neighborhood rather than their city or country.
Status seeking
Humans assign value to their social status within a group for survival and reproduction. People tend to pursue high-status positions to enjoy benefits, such as desirable mating partners. Therefore, behaviors that can produce reputational benefits are desirable to enhance one's standing in society. Altruistic acts are generally viewed positively, yield social rewards, and are cumulative. However, effective altruism, that is, altruistic behavior that focuses on maximizing others' welfare, is often not socially rewarded. Evidence-based reasoning in charitable giving may be perceived negatively, as amoral, and so will reduce a person's likability. Some have even argued that the reputational costs incurred for engaging in effective giving explain people's aversion to prioritizing some causes over more impactful ones.
Conformity
Many living organisms have demonstrated conformity, that is, the tendency to use dominant group norms (or descriptive norms) as guiding rules of behavior. Research on humans has also shown that social norms have the power to influence what others do. In the judgment and decision-making research, this observation has come to be known as the bandwagon effect. The power of this bias has also been demonstrated in the field of charitable giving. In fact, people have been shown to donate more, or to exhibit an increased likelihood to donate, when they perceived donating to charity as the social norm or the default choice. Therefore, the fact that many people become increasingly in favor of donating to ineffective options, then society will see the creation of a norm for people to give ineffectively. As a result, people rely more strongly on their intuitions which lead them to choosing to give ineffectively simply because they know that most others would do the same thing.
Motivational obstacles
Subjective preferences
People often prioritize giving to charities that align with their subjectively preferred causes. Commonly, people believe charity to be a subjective decision which should not be motivated by numbers, but by care for the cause given the lack of responsibility attributed to the effects of donations. This aligns with the theory of warm-glow giving originally proposed by the economist James Andreoni. According to Andreoni (1990), individuals gain satisfaction from the act of giving but are not concerned about the benefits generated by their act.
Narrow moral circle
Moral circle expansion is the concept of increasing one's number and kind of subjects deserving of moral concern over time. The establishment of one's moral circle depends on spatial, biological, and temporal proximity. For instance, many donors in WEIRD countries tend to favor charities that conduct work within their respective geographical boundaries. In terms of biological distance, people favor donating money to help humans instead of animals, even in cases when animals can have equal cognitive and suffering capacities. The idea of temporal proximity relates to people's tendency to prefer helping current generations over future ones.
Scope neglect (insensitivity)
Scope neglect (or scope insensitivity) is the idea that people are numb to the number of victims in large, high-stake humanitarian situations. Some research has compared this cognitive bias to the economic concept of diminishing marginal utility wherein people demonstrate a decreasing non-linear concern for individuals as the number of people increases.
Epistemic obstacles
Overhead aversion
Donors are averse to giving to charities that devote a lot of their expenses to administration or running costs. Several studies have demonstrated the ubiquitous effect of overhead aversion which is commonly attributed to people's conflation between overhead spending and charity cost-effectiveness (or impact). Furthermore, some have argued that when donors learn that a charity uses their donation to fund running costs, donors experience a diminished feeling of warm-glow, which is a significant driver of donation behavior.
Quantifiability scepticism
Intangible outcomes (such as health interventions, charity effectiveness) are hard to quantify, and many people doubt that they can every be quantified and compared. However, in disciplines such as health economics, health outcomes and interventions are quantified and evaluated using metrics such as quality-adjusted life years (QALYs). In a similar vein, happiness economists have developed the concept of wellbeing-years (WELLBYs) which evaluates effectiveness in terms of life-years lived up to full life satisfaction. Put simply, a WELLBY is given by:Where is the number of lives remaining from the region's life expectancy and is the change in life satisfaction expected to result from a particular action or intervention. Thus, charity cost-effectiveness analyses use a number of different measures grounded in academic research to quantify their impact, allowing direct comparisons of charities that address multiple causes.
Limited awareness
The effective altruism movement does substantial work on identifying the world's most effective charities through charity evaluators such as GiveWell, Giving What We Can, and Animal Charity Evaluators. However, many people are unaware of these organizations and the charities they evaluate, and are strongly driven by emotional responses when estimating the effectiveness of a charity; choosing instead to prioritize those causes to which they have a personal connection.
See also
References
Wikipedia Student Program
Effective altruism
Moral psychology
Social psychology | Psychological barriers to effective altruism | [
"Biology"
] | 1,872 | [
"Effective altruism",
"Behavior",
"Altruism"
] |
75,075,997 | https://en.wikipedia.org/wiki/267%20%28number%29 | 267 (two hundred [and] sixty-seven) is the natural number following 266 and preceding 268.
In mathematics
267 is an odd composite number with two prime factors.
267 is the number of planar partitions of the number 12. Planar partitions are the number of ways in which the given number can be organized as split in an array.
267 is the sum of perfect cubes in two different ways. It is the sum of 1³+2³+2³+5³+5³ and 2³+2³+2³+3³+6³
References
Integers | 267 (number) | [
"Mathematics"
] | 122 | [
"Elementary mathematics",
"Integers",
"Mathematical objects",
"Numbers"
] |
75,076,512 | https://en.wikipedia.org/wiki/Blue%20Ring | Blue Ring is a spacecraft platform designed to support spacecraft operation, under development by Blue Origin. The platform is to be capable of refueling, transporting, and hosting satellites. A prototype was launched on New Glenn's inaugural flight in January 2025.
The Blue Ring platform accommodates satellites using a primary payload adapter, capable of supporting a satellite, as well as 12 ESPA and ESPA Grande adapters, capable of supporting -class satellites. In total, the platform can carry up to of payload, depending on the target orbit. The platform is marketed toward a number of destination orbits, include geosynchronous orbits, Lagrange points, cislunar and lunar orbits, and potentially Interplanetary Space. Because of this capability, Blue Origin markets Blue Ring as a space tug as well as a satellite support platform. Other capabilities of Blue Ring include thermal management, communications relaying, and spacecraft refueling. Blue Ring itself is to be capable of refueling in orbit.
The spacecraft is to use a combination of chemical and electric propulsion—chemical propulsion for major maneuvers and electric propulsion for station-keeping maneuvers or to reduce the propellant demands of orbit changes. Electric power is provided by solar array wings made up of roll-out solar array blankets.
Blue Ring is designed to be launch-vehicle agnostic, allowing launch aboard carrier rockets with EELV-class fairings such as the Vulcan Centaur, Falcon 9, and Atlas V. The platform is also to be launched on Blue Origin's own New Glenn space launch vehicle.
References
Blue Origin
Service satellites | Blue Ring | [
"Astronomy"
] | 315 | [
"Astronomy stubs",
"Spacecraft stubs"
] |
75,077,678 | https://en.wikipedia.org/wiki/Overhaul%20hook%20ball | An overhaul hook ball, also known as an overhaul ball or headache ball, is a heavy weight that is attached to the end of a crane's cable, above the lifting hook. It is used to keep the cable under sufficient tension even when no load is attached. Although commonly spherical as the name suggests, overhaul balls may also be ellipsoidal or cylindrical.
Overhaul balls should be distinguished from wrecking balls, which although superficially similar looking, are different and serve a different purpose.
References
Lifting equipment | Overhaul hook ball | [
"Physics",
"Technology"
] | 104 | [
"Physical systems",
"Machines",
"Lifting equipment"
] |
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