|
Bioelectrodynamics
Bioelectrodynamics is a branch of medical physics and bioelectromagnetism which deals with rapidly changing electric and magnetic fields in biological systems, i.e. high frequency endogenous electromagnetic phenomena in living cells. Unlike the events studied by the electrophysiology, the generating mechanism of bioelectrodynamic phenomenon is not connected with currents of ions and its frequency is typically much higher. Examples include vibrations of electrically polar intracellular structures and non-thermal emission of photons as a result of metabolic activity. Theories and Hypotheses Plenty of theoretical work was published on theories and hypotheses describing generation of electromagnetic field by living cells in very broad frequency range. The most influential one was once probably the Fröhlich's hypothesis of coherence in biological systems introduced by Herbert Fröhlich in the late 1960s. Despite the fact that experimental evidence for Fröhlich's hypothesis does not exi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Herbert Fröhlich
Herbert Fröhlich (9 December 1905 – 23 January 1991) FRS was a German-born British physicist. Career In 1927, Fröhlich entered Ludwig-Maximilians University in Munich to study physics, and received his doctorate under Arnold Sommerfeld in 1930. His first position was as Privatdozent at the University of Freiburg. Due to rising anti-Semitism and the Deutsche Physik movement under Adolf Hitler, and at the invitation of Yakov Frenkel, Fröhlich went to the Soviet Union, in 1933, to work at the Ioffe Physico-Technical Institute in Leningrad. During the Great Purge following the murder of Sergei Kirov, he fled to England in 1935. Except for a short visit to the Netherlands and a brief internment during World War II, he worked in Nevill Francis Mott's department, at the University of Bristol, until 1948, rising to the position of Reader. At the invitation of James Chadwick, he took the Chair for Theoretical Physics at the University of Liverpool. In 1950 Bell Telephone Laborato ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Medical Physics
Medical physics deals with the application of the concepts and methods of physics to the prevention, diagnosis and treatment of human diseases with a specific goal of improving human health and well-being. Since 2008, medical physics has been included as a health profession according to International Standard Classification of Occupation of the International Labour Organization. Although medical physics may sometimes also be referred to as ''biomedical physics'', ''medical biophysics'', ''applied physics in medicine'', ''physics applications in medical science'', ''radiological physics'' or ''hospital radio-physics'', however a "medical physicist" is specifically a health professional with specialist education and training in the concepts and techniques of applying physics in medicine and competent to practice independently in one or more of the subfields of medical physics. Traditionally, medical physicists are found in the following healthcare specialties: radiation oncology (a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electromagnetic Spectrum
The electromagnetic spectrum is the range of frequencies (the spectrum) of electromagnetic radiation and their respective wavelengths and photon energies. The electromagnetic spectrum covers electromagnetic waves with frequencies ranging from below one hertz to above 1025 hertz, corresponding to wavelengths from thousands of kilometers down to a fraction of the size of an atomic nucleus. This frequency range is divided into separate bands, and the electromagnetic waves within each frequency band are called by different names; beginning at the low frequency (long wavelength) end of the spectrum these are: radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays at the high-frequency (short wavelength) end. The electromagnetic waves in each of these bands have different characteristics, such as how they are produced, how they interact with matter, and their practical applications. There is no known limit for long and short wavelengths. Extreme ultr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bioelectromagnetism
Bioelectromagnetics, also known as bioelectromagnetism, is the study of the interaction between electromagnetic fields and biological entities. Areas of study include electromagnetic fields produced by living cells, tissues or organisms, the effects of man-made sources of electromagnetic fields like mobile phones, and the application of electromagnetic radiation toward therapies for the treatment of various conditions. Biological phenomena Bioelectromagnetism is studied primarily through the techniques of electrophysiology. In the late eighteenth century, the Italian physician and physicist Luigi Galvani first recorded the phenomenon while dissecting a frog at a table where he had been conducting experiments with static electricity. Galvani coined the term ''animal electricity'' to describe the phenomenon, while contemporaries labeled it galvanism. Galvani and contemporaries regarded muscle activation as resulting from an electrical fluid or substance in the nerves. Short-liv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Medical Physics
Medical physics deals with the application of the concepts and methods of physics to the prevention, diagnosis and treatment of human diseases with a specific goal of improving human health and well-being. Since 2008, medical physics has been included as a health profession according to International Standard Classification of Occupation of the International Labour Organization. Although medical physics may sometimes also be referred to as ''biomedical physics'', ''medical biophysics'', ''applied physics in medicine'', ''physics applications in medical science'', ''radiological physics'' or ''hospital radio-physics'', however a "medical physicist" is specifically a health professional with specialist education and training in the concepts and techniques of applying physics in medicine and competent to practice independently in one or more of the subfields of medical physics. Traditionally, medical physicists are found in the following healthcare specialties: radiation oncology (a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Poisson Distribution
In probability theory and statistics, the Poisson distribution is a discrete probability distribution that expresses the probability of a given number of events occurring in a fixed interval of time or space if these events occur with a known constant mean rate and Statistical independence, independently of the time since the last event. It is named after France, French mathematician Siméon Denis Poisson (; ). The Poisson distribution can also be used for the number of events in other specified interval types such as distance, area, or volume. For instance, a call center receives an average of 180 calls per hour, 24 hours a day. The calls are independent; receiving one does not change the probability of when the next one will arrive. The number of calls received during any minute has a Poisson probability distribution with mean 3: the most likely numbers are 2 and 3 but 1 and 4 are also likely and there is a small probability of it being as low as zero and a very smal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coherent States
In physics, specifically in quantum mechanics, a coherent state is the specific quantum state of the quantum harmonic oscillator, often described as a state which has dynamics most closely resembling the oscillatory behavior of a classical harmonic oscillator. It was the first example of quantum dynamics when Erwin Schrödinger derived it in 1926, while searching for solutions of the Schrödinger equation that satisfy the correspondence principle. The quantum harmonic oscillator (and hence the coherent states) arise in the quantum theory of a wide range of physical systems.J.R. Klauder and B. Skagerstam, ''Coherent States'', World Scientific, Singapore, 1985. For instance, a coherent state describes the oscillating motion of a particle confined in a quadratic potential well (for an early reference, see e.g. Schiff's textbook). The coherent state describes a state in a system for which the ground-state wavepacket is displaced from the origin of the system. This state can be relate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coherence (physics)
In physics, two wave sources are coherent if their frequency and waveform are identical. Coherence is an ideal property of waves that enables stationary (i.e., temporally or spatially constant) interference. It contains several distinct concepts, which are limiting cases that never quite occur in reality but allow an understanding of the physics of waves, and has become a very important concept in quantum physics. More generally, coherence describes all properties of the correlation between physical quantities of a single wave, or between several waves or wave packets. Interference is the addition, in the mathematical sense, of wave functions. A single wave can interfere with itself, but this is still an addition of two waves (see Young's slits experiment). Constructive or destructive interference are limit cases, and two waves always interfere, even if the result of the addition is complicated or not remarkable. When interfering, two waves can add together to create a wave of g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fritz-Albert Popp
Fritz-Albert Popp (11 May 1938 – 4 August 2018) was a German researcher in biophysics, particularly in the study of biophotons. Biography Popp was born in 1938 in Frankfurt. He has a diploma in Experimental Physics (1966, University Würzburg), a Ph.D. in Theoretical Physics (1969, University Mainz), and a habilitation in Biophysics and Medicine (1973, University Marburg). He was awarded Professorship (H2) by the Senate of Marburg University, and lectured at Marburg University from 1973 to 1980. In the mid-1970s, Popp rediscovered and made the first extensive physical analysis of biophotons (they were originally discovered in 1922). He was head of a research group in the pharmaceutical industry in Worms from 1981 to 1983 and head of a research group at the Institute of Cell Biology (University of Kaiserslautern) from 1983 to 1986 and of another research group at the Technology Center in Kaiserslautern. Popp became an Invited Member and of the New York Academy of Sciences ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dielectrophoresis
Dielectrophoresis (DEP) is a phenomenon in which a force is exerted on a dielectric particle when it is subjected to a non-uniform electric field. This force does not require the particle to be charged. All particles exhibit dielectrophoretic activity in the presence of electric fields. However, the strength of the force depends strongly on the medium and particles' electrical properties, on the particles' shape and size, as well as on the frequency of the electric field. Consequently, fields of a particular frequency can manipulate particles with great selectivity. This has allowed, for example, the separation of cells or the orientation and manipulation of nanoparticles and nanowires. Furthermore, a study of the change in DEP force as a function of frequency can allow the electrical (or electrophysiological in the case of cells) properties of the particle to be elucidated. Background and properties Although the phenomenon we now call dielectrophoresis was described in passing ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemiluminescent
Chemiluminescence (also chemoluminescence) is the emission of light (luminescence) as the result of a chemical reaction. There may also be limited emission of heat. Given reactants A and B, with an excited intermediate ◊, : + -> lozenge -> roducts+ light For example, if is luminol and is hydrogen peroxide in the presence of a suitable catalyst we have: :\underset + \underset -> 3-APAlozenge-> + light where: * 3-APA is 3-aminophthalate * 3-APA ''◊is the vibronic excited state fluorescing as it decays to a lower energy level. General description The decay of this excited state ''◊to a lower energy level causes light emission. In theory, one photon of light should be given off for each molecule of reactant. This is equivalent to the Avogadro number of photons per mole of reactant. In actual practice, non-enzymatic reactions seldom exceed 1% QC, quantum efficiency. In a chemical reaction, reactants collide to form a transition state, the enthalpic maximum in a re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reactive Oxygen Species
In chemistry, reactive oxygen species (ROS) are highly reactive chemicals formed from diatomic oxygen (). Examples of ROS include peroxides, superoxide, hydroxyl radical, singlet oxygen, and alpha-oxygen. The reduction of molecular oxygen () produces superoxide (), which is the precursor to most other reactive oxygen species: :O2 + e^- -> \ ^\bullet O2- Dismutation of superoxide produces hydrogen peroxide (): :2 H+ + \ ^\bullet O2^- + \ ^\bullet O2^- -> H2O2 + O2 Hydrogen peroxide in turn may be partially reduced, thus forming hydroxide ions and hydroxyl radicals (), or fully reduced to water: :H2O2 + e^- -> HO^- + \ ^\bullet OH :2 H+ + 2 e- + H2O2 -> 2 H2O In a biological context, ROS are byproducts of the normal metabolism of oxygen. ROS have roles in cell signaling and homeostasis. ROS are intrinsic to cellular functioning, and are present at low and stationary levels in normal cells. In plants, ROS are involved in metabolic processes related to photoprotection and toleran ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.gif "Click for more on -> Medical Physics")
