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Biography
Peter Clive Thonemann
Peter Clive Thonemann (3 June 1917 – 10 February 2018) was an Australian-born British physicist who was a pioneer in the field of fusion power while working in the United Kingdom . Thonemann was born in Melbourne and moved to Oxford University in 1944, becoming one of the earliest researchers on the topic of controlled fusion. He led the fusion research at Oxford in its early years, before mo
  • 955
  • 27 Dec 2022
Biography
Norman Rasmussen
Norman C. Rasmussen (November 12, 1927 – July 18, 2003) was an American physicist.[1] Rasmussen was born in Harrisburg, Pennsylvania. He grew up on a dairy farm as the fifth of six brothers. He attended public school in Hershey, Pennsylvania. His father died when he was in eighth grade, and his family moved to Gettysburg, where his grandparents helped to care for the family. Rasmussen gradu
  • 952
  • 22 Nov 2022
Topic Review
Rigidity Theory
Rigidity theory, or topological constraint theory, is a tool for predicting properties of complex networks (such as glasses) based on their composition. It was introduced by James Charles Phillips in 1979 and 1981, and refined by Michael Thorpe in 1983. Inspired by the study of the stability of mechanical trusses as pioneered by James Clerk Maxwell, and by the seminal work on glass structure done by William Houlder Zachariasen, this theory reduces complex molecular networks to nodes (atoms, molecules, proteins, etc.) constrained by rods (chemical constraints), thus filtering out microscopic details that ultimately don't affect macroscopic properties. An equivalent theory was developed by P.K. Gupta A.R. Cooper in 1990, where rather than nodes representing atoms, they represented unit polytopes. An example of this would be the SiO tetrahedra in pure glassy silica. This style of analysis has applications in biology and chemistry, such as understanding adaptability in protein-protein interaction networks. Rigidity theory applied to the molecular networks arising from phenotypical expression of certain diseases may provide insights regarding their structure and function. In molecular networks, atoms can be constrained by radial 2-body bond-stretching constraints, which keep interatomic distances fixed, and angular 3-body bond-bending constraints, which keep angles fixed around their average values. As stated by Maxwell's criterion, a mechanical truss is isostatic when the number of constraints equals the number of degrees of freedom of the nodes. In this case, the truss is optimally constrained, being rigid but free of stress. This criterion has been applied by Phillips to molecular networks, which are called flexible, stressed-rigid or isostatic when the number of constraints per atoms is respectively lower, higher or equal to 3, the number of degrees of freedom per atom in a three-dimensional system. The same condition applies to random packing of spheres, which are isostatic at the jamming point. Typically, the conditions for glass formation will be optimal if the network is isostatic, which is for example the case for pure silica. Flexible systems show internal degrees of freedom, called floppy modes, whereas stressed-rigid ones are complexity locked by the high number of constraints and tend to crystallize instead of forming glass during a quick quenching.
  • 944
  • 09 Oct 2022
Topic Review
Inflammatory Biomarker Responses to Whole-Body Vibration
Inflammation is considered to be a vital defense mechanism for health, acting as a protective response of the immune system through a satisfactory inflammatory biomarker response (IBR). IBR, as well as being beneficial to the organism, can be also responsible for a variety of chronic inflammatory diseases. Whole-body vibration (WBV) exercise is a type of physical exercise that can act on inflammation responses due its capacity for stimulating the sensory components that promote systemic responses.
  • 939
  • 17 Jan 2023
Biography
Robert Spencer Stone
Robert Spencer Stone (5 June 1895 – 18 December 1966) was a Canadian American and pioneer in radiology, radiation therapy and radiation protection.[1] Robert Spencer Stone, M.D., LLD was born in Chatham, Kent County, Ontario the son of Spencer ‘Pen’ Stone and Flora Maude Campbell. The Pen Stone family consisted of children Robert, Thomas, John, and Elizabeth. R.S. Stone married Wilhemin
  • 937
  • 08 Dec 2022
Topic Review
RESOLFT
RESOLFT, an acronym for REversible Saturable OpticaL Fluorescence Transitions, denotes a group of optical fluorescence microscopy techniques with very high resolution. Using standard far field visible light optics a resolution far below the diffraction limit down to molecular scales can be obtained. With conventional microscopy techniques, it is not possible to distinguish features that are located at distances less than about half the wavelength used (i.e. about 200 nm for visible light). This diffraction limit is based on the wave nature of light. In conventional microscopes the limit is determined by the used wavelength and the numerical aperture of the optical system. The RESOLFT concept surmounts this limit by temporarily switching the molecules to a state in which they cannot send a (fluorescence-) signal upon illumination. This concept is different from for example electron microscopy where instead the used wavelength is much smaller.
  • 933
  • 25 Nov 2022
Topic Review
KTHNY Theory
The KTHNY-theory describes melting of crystals in two dimensions (2D). The name is derived from the initials of the surnames of John Michael Kosterlitz, David J. Thouless, Bertrand Halperin, David R. Nelson, and A. Peter Young, who developed the theory in the 1970s. It is, beside the Ising model in 2D and the XY model in 2D, one of the few theories, which can be solved analytically and which predicts a phase transition at a temperature [math]\displaystyle{ T \gt 0 }[/math].
  • 931
  • 02 Nov 2022
Topic Review
Tanpopo (Mission)
The Tanpopo mission is an orbital astrobiology experiment investigating the potential interplanetary transfer of life, organic compounds, and possible terrestrial particles in the low Earth orbit. The purpose is to assess the panspermia hypothesis and the possibility of natural interplanetary transport of microbial life as well as prebiotic organic compounds. The collection and exposure phase took place from May 2015 through February 2018 utilizing the Exposed Facility located on the exterior of Kibo, the Japanese Experimental Module of the International Space Station. The mission, designed and performed by Japan, used ultra-low density silica gel (aerogel) to collect cosmic dust by, which is being analyzed for amino acid-related compounds and microorganisms following their return to Earth. The last samples were retrieved in February 2018 and analyses are ongoing. The principal investigator is Akihiko Yamagishi, who heads a team of researchers from 26 universities and institutions in Japan, including JAXA.
  • 929
  • 14 Oct 2022
Biography
Rudolph Koenig
Karl Rudolph Koenig (26 November 1832 – 2 October 1901) was born in Königsberg of Prussia. Koenig was a businessman, instrument maker, and Germany physicist, chiefly concerned with acoustic phenomena. He was best known for designing and building acoustical instruments such as the tuning fork and sound analyser. Karl Rudolph Koening was born on 26 November 1832, a descendant of a prominent
  • 926
  • 23 Nov 2022
Topic Review
Mechanisms of Co-Evolution of Wheat and Rust Pathogens
Wheat (Triticum spp.) is a cereal crop domesticated >8000 years ago and the second-most-consumed food crop nowadays. Ever since mankind has written records, cereal rust diseases have been a painful awareness in antiquity documented in the Old Testament (about 750 B.C.). The pathogen causing the wheat stem rust disease is among the first identified plant pathogens in the 1700s, suggesting that wheat and rust pathogens have co-existed for thousands of years. With advanced molecular technologies, wheat and rust genomes have been sequenced, and interactions between the host and the rust pathogens have been extensively studied at molecular levels.
  • 926
  • 08 Jun 2023
Topic Review
Outline of Nanotechnology
The following outline is provided as an overview of and topical guide to nanotechnology: Nanotechnology is science, engineering, and technology conducted at the nanoscale, which is about 1 to 100 nanometers.
  • 923
  • 26 Oct 2022
Topic Review
Hinode
Hinode (/ˈhiːnoʊdeɪ/; Japanese: ひので, IPA: [çinode], Sunrise), formerly Solar-B, is a Japan Aerospace Exploration Agency Solar mission with United States and United Kingdom collaboration. It is the follow-up to the Yohkoh (Solar-A) mission and it was launched on the final flight of the M-V-7 rocket from Uchinoura Space Center, Japan on 22 September 2006 at 21:36 UTC (23 September, 06:36 JST). Initial orbit was perigee height 280 km, apogee height 686 km, inclination 98.3 degrees. Then the satellite maneuvered to the quasi-circular sun-synchronous orbit over the day/night terminator, which allows near-continuous observation of the Sun. On 28 October 2006, the probe's instruments captured their first images. The data from Hinode are being downloaded to the Norway , terrestrial Svalsat station, operated by Kongsberg a few kilometres west of Longyearbyen, Svalbard. From there, data was transmitted by Telenor through a fibre-optic network to mainland Norway at Harstad, and on to data users in North America, Europe and Japan.
  • 919
  • 15 Nov 2022
Biography
Sharon Glotzer
Sharon C. Glotzer is an United States "digital alchemist,"[1] the John Werner Cahn Distinguished University Professor of Engineering and the Stuart W. Churchill Collegiate Professor of Chemical Engineering at the University of Michigan, where she is also Professor of Materials Science & Engineering, Professor of Physics, Professor of Macromolecular Science & Engineering, and Professor of Applied
  • 913
  • 28 Nov 2022
Biography
Chih-Kung Jen
Chih-Kung Jen (Chinese: 任之恭; pinyin: Rén Zhīgōng; August 15 or October 2, 1906 – November 19, 1995) was a Chinese physicist who emigrated to the U.S. and participated in some of the 20th century's major scientific, political and social developments in both the United States and China. Born in a mud house in a remote and largely illiterate village in China, he was awarded a scholarshi
  • 911
  • 09 Dec 2022
Topic Review
Natural Circulation
Convection is single or multiphase fluid flow that occurs spontaneously due to the combined effects of material property heterogeneity and body forces on a fluid, most commonly density and gravity (see buoyancy). When the cause of the convection is unspecified, convection due to the effects of thermal expansion and buoyancy can be assumed. Convection may also take place in soft solids or mixtures where particles can flow. Convective flow may be transient (such as when a multiphase mixture of oil and water separates) or steady state (see Convection cell). The convection may be due to gravitational, electromagnetic or fictitious body forces. Heat transfer by natural convection plays a role in the structure of Earth's atmosphere, its oceans, and its mantle. Discrete convective cells in the atmosphere can be identified by clouds, with stronger convection resulting in thunderstorms. Natural convection also plays a role in stellar physics. Convection is often categorised or described by the main effect causing the convective flow, e.g. Thermal convection. Convection cannot take place in most solids because neither bulk current flows nor significant diffusion of matter can take place.
  • 910
  • 07 Nov 2022
Topic Review
Locating an Electron with an Ideal Microscope
A photon (from grc φῶς, φωτός (Script error: No such module "Ancient Greek".) 'light') is an elementary particle that is a quantum of the electromagnetic field, including electromagnetic radiation such as light and radio waves, and the force carrier for the electromagnetic force. Photons are massless,[lower-alpha 1] so they always move at the speed of light in vacuum, 299792458 m/s (or about 186,282 mi/s). The photon belongs to the class of bosons. Like all elementary particles, photons are currently best explained by quantum mechanics, and exhibit wave–particle duality, their behavior featuring properties of both waves and particles. The modern photon concept originated during the first two decades of the 20th century with the work of Albert Einstein, who built upon the research of Max Planck. While trying to explain how matter and electromagnetic radiation could be in thermal equilibrium with one another, Planck proposed that the energy stored within a material object should be regarded as composed of an integer number of discrete, equal-sized parts. To explain the photoelectric effect, Einstein introduced the idea that light itself is made of discrete units of energy. In 1926, Gilbert N. Lewis popularized the term photon for these energy units. Subsequently, many other experiments validated Einstein's approach. In the Standard Model of particle physics, photons and other elementary particles are described as a necessary consequence of physical laws having a certain symmetry at every point in spacetime. The intrinsic properties of particles, such as charge, mass, and spin, are determined by gauge symmetry. The photon concept has led to momentous advances in experimental and theoretical physics, including lasers, Bose–Einstein condensation, quantum field theory, and the probabilistic interpretation of quantum mechanics. It has been applied to photochemistry, high-resolution microscopy, and measurements of molecular distances. Moreover, photons have been studied as elements of quantum computers, and for applications in optical imaging and optical communication such as quantum cryptography.
  • 909
  • 09 Nov 2022
Biography
Wilhelm Hanle
Wilhelm Hanle (13 January 1901 – 29 April 1993, Gießen) was a German experimental physicist. He is known for the Hanle effect. During World War II, he made contributions to the German nuclear energy project, also known as the Uranium Club. From 1941 until emeritus status in 1969, he was an ordinarius professor of experimental physics and held the chair of physics at the University of Giessen.
  • 909
  • 18 Nov 2022
Topic Review
Minimal Model
In theoretical physics, a minimal model or Virasoro minimal model is a two-dimensional conformal field theory whose spectrum is built from finitely many irreducible representations of the Virasoro algebra. Minimal models have been classified and solved, and found to obey an ADE classification. The term minimal model can also refer to a rational CFT based on an algebra that is larger than the Virasoro algebra, such as a W-algebra.
  • 906
  • 17 Oct 2022
Topic Review
Copernicus Programme
Copernicus is the European Union's Earth observation programme coordinated and managed by the European Commission in partnership with the European Space Agency (ESA), the EU Member States and EU Agencies. It aims at achieving a global, continuous, autonomous, high quality, wide range Earth observation capacity. Providing accurate, timely and easily accessible information to, among other things, improve the management of the environment, understand and mitigate the effects of climate change, and ensure civil security. The objective is to use vast amount of global data from satellites and from ground-based, airborne and seaborne measurement systems to produce timely and quality information, services and knowledge, and to provide autonomous and independent access to information in the domains of environment and security on a global level in order to help service providers, public authorities and other international organizations improve the quality of life for the citizens of Europe. In other words, it pulls together all the information obtained by the Copernicus environmental satellites, air and ground stations and sensors to provide a comprehensive picture of the "health" of Earth. One of the benefits of the Copernicus Programme is that the data and information produced in the framework of Copernicus are made available free-of-charge to all its users and the public, thus allowing downstream services to be developed. The services offered by Copernicus cover six main interacting themes: atmosphere, marine, land, climate, emergency and security. Copernicus builds upon three components: Its cost during 1998 to 2020 are estimated at 6.7 billion euros with around €4.3bn spent in the period 2014 to 2020 and shared between the EU (66%) and ESA (33%) with benefits of the data to the EU economy estimated at roughly 30 billion euros through 2030. ESA as a main partner has performed much of the design and oversees and co-funds the development of Sentinel missions 1, 2, 3, 4, 5 and 6 with each Sentinel mission consisting of at least 2 satellites and some, such as Sentinel 1, consisting of 4 satellites. They will also provide the instruments for Meteosat Third Generation and MetOp-SG weather satellites of EUMETSAT where ESA and EUMETSAT will also coordinate the delivery of data from upwards of 30 satellites that form the contributing satellite missions to Copernicus.
  • 904
  • 11 Nov 2022
Topic Review
Chromatin Architecture and Damage Response
DNA double-strand breaks (DSBs) have been recognized as the most serious lesions in irradiated cells. While several biochemical pathways capable of repairing these lesions have been identified, the mechanisms by which cells select a specific pathway for activation at a given DSB site remain poorly understood. The impact of chromatin and repair foci architecture on these mechanisms can be elucidated by super-resolution microscopy in combination with mathematical approaches of topology. These aspects are discussed in relation to state of the art knowledge of ionizing radiation induced damaging of cell nuclei and DNA repair.
  • 902
  • 20 Feb 2021
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