David Cohen (physicist)
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David Cohen (physicist)
David Cohen made many of the first pioneering measurements in the area of biomagnetism (magnetic fields produced by the body), although he was initially trained as a nuclear physicist. Early life and education Cohen was born of immigrant parents in Winnipeg, Manitoba, Canada. He was raised there and earned a B.A. degree at the University of Manitoba. Then, he attended graduate school at the University of California, Berkeley, where he gained a Ph.D. in experimental nuclear physics. Career Working in this area, and using large magnets, he became interested in the other extreme; this was the measurement of very weak magnetic fields, which for example might be produced by the weak natural currents in the human body. In 1963, he proposed a method using a magnetically shielded room to keep out external magnetic disturbances, as in radiation shielding in nuclear experiments. At that time others reported the first biomagnetic measurement, where the MCG (''magnetocardiogram'', the magneti ...
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Biomagnetism
Biomagnetism is the phenomenon of magnetic fields ''produced'' by living organisms; it is a subset of bioelectromagnetism. In contrast, organisms' use of magnetism in navigation is magnetoception and the study of the magnetic fields' ''effects'' on organisms is '' magnetobiology''. (The word biomagnetism has also been used loosely to include magnetobiology, further encompassing almost any combination of the words magnetism, cosmology, and biology, such as "magnetoastrobiology".) The origin of the word biomagnetism is unclear, but seems to have appeared several hundred years ago, linked to the expression "animal magnetism". The present scientific definition took form in the 1970s, when an increasing number of researchers began to measure the magnetic fields produced by the human body. The first valid measurement was actually made in 1963, but the field of research began to expand only after a low-noise technique was developed in 1970.{{cite journal , last1=Cohen , first1=David , ...
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Magnetomyography
Magnetomyography (MMG) is a technique for mapping muscle activity by recording magnetic fields produced by electrical currents occurring naturally in the muscles, using arrays of SQUIDs (superconducting quantum interference devices). It has a better capability than electromyography for detecting slow or direct currents. The magnitude of the MMG signal is in the scale of pico (10−12) to femto (10−15) Tesla (T). Miniaturizing MMG offers a prospect to modernize the bulky SQUID to wearable miniaturized magnetic sensors. Two key drivers for the development of the MMG method: 1) poor spatial resolution of the EMG signals when recorded non-invasively on the skin where state-of-the-art EMG measurements are even using needle recording probes, which is possible to accurately assess muscle activity but painful and limited to tiny areas with poor spatial sampling points; 2) poor biocompatibility of the implantable EMG sensors due to the metal-tissue interface. The MMG sensors have the poten ...
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Harvard Medical School Faculty
Harvard University is a private Ivy League research university in Cambridge, Massachusetts. Founded in 1636 as Harvard College and named for its first benefactor, the Puritan clergyman John Harvard, it is the oldest institution of higher learning in the United States and one of the most prestigious and highly ranked universities in the world. The university is composed of ten academic faculties plus Harvard Radcliffe Institute. The Faculty of Arts and Sciences offers study in a wide range of undergraduate and graduate academic disciplines, and other faculties offer only graduate degrees, including professional degrees. Harvard has three main campuses: the Cambridge campus centered on Harvard Yard; an adjoining campus immediately across Charles River in the Allston neighborhood of Boston; and the medical campus in Boston's Longwood Medical Area. Harvard's endowment is valued at $50.9 billion, making it the wealthiest academic institution in the world. Endowment inc ...
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Living People
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Experimental Physicists
An experiment is a procedure carried out to support or refute a hypothesis, or determine the efficacy or likelihood of something previously untried. Experiments provide insight into cause-and-effect by demonstrating what outcome occurs when a particular factor is manipulated. Experiments vary greatly in goal and scale but always rely on repeatable procedure and logical analysis of the results. There also exist natural experimental studies. A child may carry out basic experiments to understand how things fall to the ground, while teams of scientists may take years of systematic investigation to advance their understanding of a phenomenon. Experiments and other types of hands-on activities are very important to student learning in the science classroom. Experiments can raise test scores and help a student become more engaged and interested in the material they are learning, especially when used over time. Experiments can vary from personal and informal natural comparisons (e ...
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Canadian Nuclear Physicists
Canadians (french: Canadiens) are people identified with the country of Canada. This connection may be residential, legal, historical or cultural. For most Canadians, many (or all) of these connections exist and are collectively the source of their being ''Canadian''. Canada is a multilingual and multicultural society home to people of groups of many different ethnic, religious, and national origins, with the majority of the population made up of Old World immigrants and their descendants. Following the initial period of French and then the much larger British colonization, different waves (or peaks) of immigration and settlement of non-indigenous peoples took place over the course of nearly two centuries and continue today. Elements of Indigenous, French, British, and more recent immigrant customs, languages, and religions have combined to form the culture of Canada, and thus a Canadian identity. Canada has also been strongly influenced by its linguistic, geographic, and e ...
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Canadian Physicists
Canadians (french: Canadiens) are people identified with the country of Canada. This connection may be residential, legal, historical or cultural. For most Canadians, many (or all) of these connections exist and are collectively the source of their being ''Canadian''. Canada is a multilingual and multicultural society home to people of groups of many different ethnic, religious, and national origins, with the majority of the population made up of Old World immigrants and their descendants. Following the initial period of French and then the much larger British colonization, different waves (or peaks) of immigration and settlement of non-indigenous peoples took place over the course of nearly two centuries and continue today. Elements of Indigenous, French, British, and more recent immigrant customs, languages, and religions have combined to form the culture of Canada, and thus a Canadian identity. Canada has also been strongly influenced by its linguistic, geographic, an ...
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Canadian Biophysicists
Canadians (french: Canadiens) are people identified with the country of Canada. This connection may be residential, legal, historical or cultural. For most Canadians, many (or all) of these connections exist and are collectively the source of their being ''Canadian''. Canada is a multilingual and multicultural society home to people of groups of many different ethnic, religious, and national origins, with the majority of the population made up of Old World immigrants and their descendants. Following the initial period of French and then the much larger British colonization, different waves (or peaks) of immigration and settlement of non-indigenous peoples took place over the course of nearly two centuries and continue today. Elements of Indigenous, French, British, and more recent immigrant customs, languages, and religions have combined to form the culture of Canada, and thus a Canadian identity. Canada has also been strongly influenced by its linguistic, geographic, and ec ...
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Biomagnetism
Biomagnetism is the phenomenon of magnetic fields ''produced'' by living organisms; it is a subset of bioelectromagnetism. In contrast, organisms' use of magnetism in navigation is magnetoception and the study of the magnetic fields' ''effects'' on organisms is '' magnetobiology''. (The word biomagnetism has also been used loosely to include magnetobiology, further encompassing almost any combination of the words magnetism, cosmology, and biology, such as "magnetoastrobiology".) The origin of the word biomagnetism is unclear, but seems to have appeared several hundred years ago, linked to the expression "animal magnetism". The present scientific definition took form in the 1970s, when an increasing number of researchers began to measure the magnetic fields produced by the human body. The first valid measurement was actually made in 1963, but the field of research began to expand only after a low-noise technique was developed in 1970.{{cite journal , last1=Cohen , first1=David , ...
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Magnetoencephalography
Magnetoencephalography (MEG) is a functional neuroimaging technique for mapping brain activity by recording magnetic fields produced by electrical currents occurring naturally in the brain, using very sensitive magnetometers. Arrays of SQUIDs (superconducting quantum interference devices) are currently the most common magnetometer, while the SERF (spin exchange relaxation-free) magnetometer is being investigated for future machines. Applications of MEG include basic research into perceptual and cognitive brain processes, localizing regions affected by pathology before surgical removal, determining the function of various parts of the brain, and neurofeedback. This can be applied in a clinical setting to find locations of abnormalities as well as in an experimental setting to simply measure brain activity. History MEG signals were first measured by University of Illinois physicist David Cohen in 1968, before the availability of the SQUID, using a copper induction coil as the ...
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Winnipeg
Winnipeg () is the capital and largest city of the province of Manitoba in Canada. It is centred on the confluence of the Red and Assiniboine rivers, near the longitudinal centre of North America. , Winnipeg had a city population of 749,607 and a metropolitan population of 834,678, making it the sixth-largest city, and eighth-largest metropolitan area in Canada. The city is named after the nearby Lake Winnipeg; the name comes from the Western Cree words for "muddy water" - “winipīhk”. The region was a trading centre for Indigenous peoples long before the arrival of Europeans; it is the traditional territory of the Anishinabe (Ojibway), Ininew (Cree), Oji-Cree, Dene, and Dakota, and is the birthplace of the Métis Nation. French traders built the first fort on the site in 1738. A settlement was later founded by the Selkirk settlers of the Red River Colony in 1812, the nucleus of which was incorporated as the City of Winnipeg in 1873. Being far inland, the loca ...
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