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Per Bak
Per Bak (8 December 1948 – 16 October 2002) was a Danish theoretical physicist who coauthored the 1987 academic paper that coined the term "self-organized criticality." Life and work After receiving his Ph.D. from the Technical University of Denmark in 1974, Bak worked at Brookhaven National Laboratory. He specialized in phase transitions, such as those occurring when an insulator suddenly becomes a conductor or when water freezes. In that context, he also did important work on complicated spatially modulated (magnetic) structures in solids. This research led him to the more general question of how organization emerges from disorder. In 1987, he and two postdoctoral researchers, Chao Tang and Kurt Wiesenfeld, published an article in ''Physical Review Letters'' setting a new concept they called self-organized criticality. The first discovered example of a dynamical system displaying such self-organized criticality, the Bak-Tang-Wiesenfeld sandpile model, was named after the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brønderslev
Brønderslev is a city in Denmark with a population of 12,549 (1 January 2022). The city is the largest urban area in Brønderslev Municipality and is the municipal seat. It is the fourth largest city of Vendsyssel within the North Jutland Region. History The name of the town is derived from a local Norsemen chief, Brunder. Brønderslev was formerly known as ''Vester Brønderslev'', in contrast to the neighboring ''Øster Brønderslev''. As of 2020, Øster Brønderslev has a population of just 943. Vester Brønderslev was once a small farming village. In 1682, it consisted of just 27 farms and 47 houses. The town was not initially located on any major thoroughfares and saw very little traffic. Thus, the town grew comparatively gradually. By the 1850s, however, an inn and an established market had begun to draw more traders to settle on the road near the city. In 1871, the Vendsyssel railway line opened which connected Brønderslev to Aalborg and Hjørring. The station was locate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrical Insulation
An electrical insulator is a material in which electric current does not flow freely. The atoms of the insulator have tightly bound electrons which cannot readily move. Other materials—semiconductors and conductors—conduct electric current more easily. The property that distinguishes an insulator is its resistivity; insulators have higher resistivity than semiconductors or conductors. The most common examples are non-metals. A perfect insulator does not exist because even insulators contain small numbers of mobile charges ( charge carriers) which can carry current. In addition, all insulators become electrically conductive when a sufficiently large voltage is applied that the electric field tears electrons away from the atoms. This is known as the breakdown voltage of an insulator. Some materials such as glass, paper and PTFE, which have high resistivity, are very good electrical insulators. A much larger class of materials, even though they may have lower bulk resistivit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deaths From Myelodysplastic Syndrome
Death is the irreversible cessation of all biological functions that sustain an organism. For organisms with a brain, death can also be defined as the irreversible cessation of functioning of the whole brain, including brainstem, and brain death is sometimes used as a legal definition of death. The remains of a former organism normally begin to decompose shortly after death. Death is an inevitable process that eventually occurs in almost all organisms. Death is generally applied to whole organisms; the similar process seen in individual components of an organism, such as cells or tissues, is necrosis. Something that is not considered an organism, such as a virus, can be physically destroyed but is not said to die. As of the early 21st century, over 150,000 humans die each day, with ageing being by far the most common cause of death. Many cultures and religions have the idea of an afterlife, and also may hold the idea of judgement of good and bad deeds in one's life (heaven, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1948 Births
Events January * January 1 ** The General Agreement on Tariffs and Trade (GATT) is inaugurated. ** The Constitution of New Jersey (later subject to amendment) goes into effect. ** The railways of Britain are nationalized, to form British Railways. * January 4 – Burma gains its independence from the United Kingdom, becoming an independent republic, named the ''Union of Burma'', with Sao Shwe Thaik as its first President, and U Nu its first Prime Minister. * January 5 ** Warner Brothers shows the first color newsreel (''Tournament of Roses Parade'' and the ''Rose Bowl Game''). ** The first Kinsey Reports, Kinsey Report, ''Sexual Behavior in the Human Male'', is published in the United States. * January 7 – Mantell UFO incident: Kentucky Air National Guard pilot Thomas Mantell crashes while in pursuit of an unidentified flying object. * January 12 – Mahatma Gandhi begins his fast-unto-death in Delhi, to stop communal violence during the Partition of India. * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
University Of Calgary
The University of Calgary (U of C or UCalgary) is a public research university located in Calgary, Alberta, Canada. The University of Calgary started in 1944 as the Calgary branch of the University of Alberta, founded in 1908, prior to being instituted into a separate, autonomous university in 1966. It is composed of 14 faculties and over 85 research institutes and centres. The main campus is located in the northwest quadrant of the city near the Bow River and a smaller south campus is located in the city centre. The main campus houses most of the research facilities and works with provincial and federal research and regulatory agencies, several of which are housed next to the campus such as the Geological Survey of Canada. The main campus covers approximately . A member of the U15, the University of Calgary is also one of Canada's top research universities (based on the number of Canada Research Chairs). The university has a sponsored research revenue of $380.4 million, wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maya Paczuski
Maya Paczuski is the head and founder of the Complexity Science Group at the University of Calgary. She is a well-cited physicist whose work spans self-organized criticality, avalanche dynamics, earthquake, and complex networks. She was born in Israel in 1963, but grew up in the United States. Maya Paczuski received a B.S. and M.S. in Electrical Engineering and Computer Science from M.I.T. in 1986 and then went on to study with Mehran Kardar, earning her Ph.D in Condensed matter physics from the same institute. Before founding the Complexity Science Group at the University of Calgary, she held appointments at numerous institutions around the world, most notably, M.I.T., Brookhaven National Laboratory, the Niels Bohr Institute (Copenhagen, Denmark), the University of Houston, NORDITA (Copenhagen, Denmark), Imperial College London, the von Neumann Institute for Computing at Forschungszentrum Jülich, and the Perimeter Institute for Theoretical Physics, where she organized and ran t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Myelodysplastic Syndrome
A myelodysplastic syndrome (MDS) is one of a group of cancers in which immature blood cells in the bone marrow do not mature, and as a result, do not develop into healthy blood cells. Early on, no symptoms typically are seen. Later, symptoms may include feeling tired, shortness of breath, bleeding disorders, anemia, or frequent infections. Some types may develop into acute myeloid leukemia. Risk factors include previous chemotherapy or radiation therapy, exposure to certain chemicals such as tobacco smoke, pesticides, and benzene, and exposure to heavy metals such as mercury or lead. Problems with blood cell formation result in some combination of low red blood cell, platelet, and white blood cell counts. Some types have an increase in immature blood cells, called blasts, in the bone marrow or blood. The types of MDS are based on specific changes in the blood cells and bone marrow. Treatments may include supportive care, drug therapy, and hematopoietic stem cell transplantati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bak-Tang-Wiesenfeld Sandpile
The Abelian sandpile model (ASM) is the more popular name of the original Bak–Tang–Wiesenfeld model (BTW). BTW model was the first discovered example of a dynamical system displaying self-organized criticality. It was introduced by Per Bak, Chao Tang and Kurt Wiesenfeld in a 1987 paper. Three years later Deepak Dhar discovered that the BTW sandpile model indeed follows the abelian dynamics and therefore referred to this model as the Abelian sandpile model. The model is a cellular automaton. In its original formulation, each site on a finite grid has an associated value that corresponds to the slope of the pile. This slope builds up as "grains of sand" (or "chips") are randomly placed onto the pile, until the slope exceeds a specific threshold value at which time that site collapses transferring sand into the adjacent sites, increasing their slope. Bak, Tang, and Wiesenfeld considered process of successive random placement of sand grains on the grid; each such placemen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dynamical System
In mathematics, a dynamical system is a system in which a Function (mathematics), function describes the time dependence of a Point (geometry), point in an ambient space. Examples include the mathematical models that describe the swinging of a clock pendulum, fluid dynamics, the flow of water in a pipe, the Brownian motion, random motion of particles in the air, and population dynamics, the number of fish each springtime in a lake. The most general definition unifies several concepts in mathematics such as ordinary differential equations and ergodic theory by allowing different choices of the space and how time is measured. Time can be measured by integers, by real number, real or complex numbers or can be a more general algebraic object, losing the memory of its physical origin, and the space may be a manifold or simply a Set (mathematics), set, without the need of a Differentiability, smooth space-time structure defined on it. At any given time, a dynamical system has a State ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Physical Review Letters
''Physical Review Letters'' (''PRL''), established in 1958, is a peer-reviewed, scientific journal that is published 52 times per year by the American Physical Society. As also confirmed by various measurement standards, which include the ''Journal Citation Reports'' impact factor and the journal ''h''-index proposed by Google Scholar, many physicists and other scientists consider ''Physical Review Letters'' to be one of the most prestigious journals in the field of physics. ''According to Google Scholar, PRL is the journal with the 9th journal h-index among all scientific journals'' ''PRL'' is published as a print journal, and is in electronic format, online and CD-ROM. Its focus is rapid dissemination of significant, or notable, results of fundamental research on all topics related to all fields of physics. This is accomplished by rapid publication of short reports, called "Letters". Papers are published and available electronically one article at a time. When published in s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kurt Wiesenfeld
Kurt Wiesenfeld is an American physicist working primarily on non-linear dynamics. His works primarily concern stochastic resonance, spontaneous synchronization of coupled oscillators, and non-linear laser dynamics. Since 1987, he has been professor of physics at the Georgia Institute of Technology. Life and work Kurt Wiesenfeld received his Bachelor of Science in Physics from the Massachusetts Institute of Technology in 1979, after which he moved to University of California, Berkeley and received his doctorate in 1985. From 1984 to 1985 he was a Lecturer and Research Scientist at the University of California at Santa Cruz. In 1987, as a post-doctoral research scientist in the Solid State Theory Group of Brookhaven National Laboratory, he and another fellow post-doctoral scientist, Chao Tang, along with their mentor, Per Bak, presented new ideas in group organization with a concept they coined self-organized criticality in their paper in ''Physical Review Letters.'' The first ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
