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magnetic pulsation (physics)
...in the magnetic field (hence their older name, micropulsations). These waves typically have amplitudes ranging from 100 to 0.1 nanoteslas, with lower frequencies exhibiting larger amplitudes. Magnetic pulsations have been classified phenomenologically on the basis of waveform into pulsations continuous (Pc) and pulsations irregular (Pi). Each class is subdivided into different frequency......
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magnetic quantum number (physics)
There is a magnetic quantum number also associated with the angular momentum of the quantum state. For a given orbital momentum quantum number l, there are 2l + 1 integral magnetic quantum numbers ml ranging from −l to l, which restrict the fraction of the total angular momentum along the quantization axis so that they are limited to......
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magnetic random access memory (electronics)
Another approach to information storage that is dependent on designing nanometre-thick magnetic layers is under commercial development. Known as magnetic random access memory (MRAM), a line of electrically switchable magnetic material is separated from a permanently magnetized layer by a nanoscale nonmagnetic interlayer. A resistance change that depends on the relative alignment of the fields......
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magnetic reconnection (atmospheric science)
The observed dependence of geomagnetic activity on the orientation of the IMF is explained by most researchers as a consequence of magnetic reconnection. In reconnection, two oppositely directed magnetic fields are brought together by flowing plasmas at an x-type neutral line. Far from the neutral line the magnetic field is frozen in the plasma; however, near the neutral line it becomes......
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magnetic recording (electronics)
method of preserving sounds, pictures, and data in the form of electrical signals through the selective magnetization of portions of a magnetic material. The principle of magnetic recording was first demonstrated by the Danish engineer Valdemar Poulsen in 1900, when he introduced a machine called the telegraphone that recorded speech magnetically on steel wire...
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magnetic repulsion (physics)
attraction or repulsion that arises between electrically charged particles because of their motion; the basic force responsible for the action of electric motors and the attraction of magnets for iron. Electric forces exist among stationary electric charges; both electric and magnetic forces exist among moving electric charges. The magnetic force between two ...
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magnetic resistance (magnetism)
...is related to the current, i, in the circuit by E = Ri, where R is the resistance of the circuit. In the magnetic circuit F = rϕ, where r is the reluctance of the magnetic circuit and is equivalent to resistance in the electric circuit. Reluctance is obtained by dividing the length of the magnetic path l by the permeability times th...
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magnetic resonance (physics)
absorption or emission of electromagnetic radiation by electrons or atomic nuclei in response to the application of certain magnetic fields. The principles of magnetic resonance are applied in the laboratory to analyze the atomic and nuclear properties of matter....
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magnetic resonance accelerator (instrument)
any of a class of devices that accelerates charged atomic or subatomic particles in a constant magnetic field. The first particle accelerator of this type was developed in the early 1930s by the American physicists Ernest O. Lawrence and M. Stanley Livingston. A cyclotron consists of two hollow semicircular electrodes, called dees, mounted ...
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magnetic resonance angiography (physics)
Magnetic resonance angiography, a unique form of MRI technology, can be used to produce an image of flowing blood. This permits the visualization of arteries and veins without the need for needles, catheters, or contrast agents....
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magnetic resonance imaging (medicine)
three-dimensional diagnostic imaging technique used to visualize organs and structures inside the body without the need for X-rays or other radiation. Magnetic resonance imaging (MRI) is valuable for providing detailed anatomical images and can reveal minute changes that occur over time. MRIs can be used to detect structural abnormalities th...
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magnetic resonance spectrometry (chemistry)
Magnetic resonance spectra are indispensable today for studies in heterocyclic chemistry. Proton resonance spectra, the most common type, yield information regarding the number of hydrogen atoms in the molecule, their chemical environment, and their relative orientation in space. Mass spectra are used to determine not only the complete molecular formula of the compound but also the molecular......
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magnetic resonance spectroscopy (medicine)
diagnostic imaging technique based on the detection of metabolites in tissues. Magnetic resonance spectroscopy (MRS) is related to magnetic resonance imaging (MRI) in that it uses the same machinery; however, instead of measuring blood flow, MRS measures the concentration of specific chemicals, such as neurotransm...
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magnetic reversal (geophysics)
an alternation of the Earth’s magnetic polarity in geologic time. See polar wandering....
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magnetic Reynolds number (physics)
combination of quantities that indicates the dynamic behaviour of a plasma. This number is analogous to the Reynolds number of ordinary fluid mechanics, which is used to determine whether or not a fluid flow will smooth out or become turbulent. If the magnetic permeability of free space is represented by μ0 (a constant of proportionality used in express...
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magnetic saturation (physics)
...temperature, corresponding to Curie’s law. When the value of (mB/kT) is large enough to align nearly all the dipoles with the field, the magnetization approaches a saturation value....
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magnetic sensor (engineering)
...circuit to the coils, turning them on and off. The reluctor ring is mounted on the crankshaft so that as the crankshaft rotates the magnetic sensor is triggered by notches in the reluctor ring. The magnetic sensor provides position information to the electronic control module, which governs ignition timing....
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magnetic separation
Magnetic separation is based on the differing degrees of attraction exerted on various minerals by magnetic fields. Success requires that the feed particles fall within a special size spectrum (0.1 to 1 millimetre). With good results, strongly magnetic minerals such as magnetite, franklinite, and pyrrhotite can be removed from gangue minerals by low-intensity magnetic separators. High-intensity......
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Magnetic South Pole (geophysics)
The volume of South Polar ice must have fluctuated greatly at times since the birth of the ice sheets. Glacial erratics and glacially striated rocks on mountain summits now high above current ice-sheet levels testify to an overriding by ice at much higher levels. General lowering of levels caused some former glaciers flowing from the polar region through the Transantarctic Mountains to recede......
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magnetic spin quantum number (physics)
...angular momenta. The spin quantum number is s = 12, so in the presence of a magnetic field an electron can have one of two orientations corresponding to magnetic spin quantum number ms = ±12. The Pauli exclusion principle requires that no two electrons in an atom have the same......
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magnetic storm (atmospheric science)
disturbance of the Earth’s upper atmosphere brought on by solar flares—i.e., bright eruptions from the visible portion of the Sun’s chromosphere. The material associated with these flares consists primarily of protons and electrons with an energy of a few thousand electron volts. Called plasma, this material move...
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magnetic survey (geophysics)
one of the tools used by the exploration geophysicist in his search for mineral-bearing ore bodies or even oil-bearing sedimentary structures. The essential feature is the measurement of the magnetic-field intensity and sometimes the magnetic inclination, or dip, and declination (departure from geographic north) at several stations. If the object of the survey is to make a rapi...
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magnetic susceptibility (physics)
quantitative measure of the extent to which a material may be magnetized in relation to a given applied magnetic field. The magnetic susceptibility of a material, commonly symbolized by χm, is equal to the ratio of the magnetization M within the material to the applied magnetic field strength H, or χm...
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magnetic tape (electronics)
Magnetic tape devices. Magnetic tape provides a compact, economical means of preserving and reproducing varied forms of information. Recordings on tape can be played back immediately and are easily erased, permitting the tape to be reused many times without a loss in quality of recording. For these reasons, tape is the most widely used of the various magnetic recording mediums. It......
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magnetic thermometer (instrument)
Other thermometers operate by sensing sound waves or magnetic conditions associated with temperature changes. Magnetic thermometers increase in efficiency as temperature decreases, which makes them extremely useful in measuring very low temperatures with precision. Temperatures can also be mapped, using a technique called thermography that provides a graphic or visual representation of the......
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magnetic variable star (astronomy)
Spectrum and magnetic variables, mostly of spectral type A, show only small amplitudes of light variation but often pronounced spectroscopic changes. Their spectra typically show strong lines of metals such as manganese, titanium, iron, chromium, and the lanthanides (also called rare earths), which vary periodically in intensity. These stars have strong magnetic fields, typically from a few......
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magnetic variation (compass)
...needle did not point true north from all locations but made an angle with the local meridian. This phenomenon was originally called by seamen the northeasting of the needle but is now called the variation or declination. For a time, compass makers in northern countries mounted the needle askew on the card so that the fleur-de-lis indicated true north when the needle pointed to magnetic......
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magnetic videodisc
The magnetic videodisc has an oxide-coated surface onto which input signals are recorded as magnetic patterns in spiral tracks. The video heads of the playback unit pick up these impressions and produce electrical signals that are converted back into pictures and sounds (see also magnetic recording)....
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magnetic-core storage (computing)
any of a class of computer memory devices consisting of a large array of tiny toruses of a hard magnetic material that can be magnetized in either of two directions (see computer memory)....
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magnetic-flux quantization (physics)
...properties, including the fact that any internal magnetic flux in superconductors exists only in discrete amounts (instead of in a continuous spectrum of values), an effect called the quantization of magnetic flux. This flux quantization, which had been predicted from quantum mechanical principles, was first observed experimentally in 1961....
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magnetic-polarity time scale (geology)
...lavas were extruded from the mid-oceanic ridges, they were alternately magnetized parallel and opposite to the present magnetic field of the Earth and are thus referred to as normal and reversed. A magnetic-polarity time scale for the stratigraphy of normal and reversed magnetic stripes can be constructed back as far as the middle of the Jurassic Period, about 170 million years ago, which is......
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magnetism (physics)
phenomenon associated with the motion of electric charges. This motion can take many forms. It can be an electric current in a conductor or charged particles moving through space, or it can be the motion of an electron in atomic orbit. Magnetism is also associated with elementary particles, such as the electron, that have a property called spin....
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magnetism, terrestrial (geophysics)
magnetic field associated with the Earth. It primarily is dipolar (i.e., it has two poles, these being the north and south magnetic poles) on the Earth’s surface. Away from the surface the dipole becomes distorted....
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magnetite (mineral)
iron oxide mineral (FeFe2O4, or Fe3O4) that is the chief member of one of the series of the spinel group. Minerals in this series form black to brownish, metallic, moderately hard octahedrons and masses in igneous and metamorphic rocks and in granite pegmatites, stony meteorites, and high-temperature sulfide veins. The magnetite series...
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magnetite series (mineralogy)
...group is divided into three immiscible series: the spinel (aluminum-spinel) series, in which B is aluminum; the chromite (chromium-spinel) series, in which B is chromium; and the magnetite (iron-spinel) series, in which B is iron....
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magnetization (physics)
...field, matter is either attracted or repelled in the direction of the gradient of the field. This property is described by the magnetic susceptibility of the matter and depends on the degree of magnetization of the matter in the field. Magnetization depends on the size of the dipole moments of the atoms in a substance and the degree to which the dipole moments are aligned with respect to......
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magnetization electron (physics)
...are thought to be the result of the magnetic moment associated with the spin of an electron in an outer atomic shell—specifically, the third d shell. Such electrons are referred to as magnetization electrons. The Pauli exclusion principle prohibits two electrons from having identical properties; for example, no two electrons can be in the same location and have spins in the same.....
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magneto (instrument)
permanent-magnet generator mainly employed for ignition of compressed gasses in internal combustion engines. Primary applications have been in small aircraft, marine, tractor, and motorcycle engines, which may not have an available battery supply. The major parts of the magneto are a permanent-magnet rotor, an armature with a primary winding containing a small...
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magneto-optical disk (computing)
Magneto-optical discs are a hybrid storage medium. In reading, spots with different directions of magnetization give different polarization in the reflected light of a low-power laser beam. In writing, every spot on the disk is first heated by a strong laser beam and then cooled under a magnetic field, magnetizing every spot in one direction, to store all 0s. The writing process then reverses......
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magneto-optical shutter (photography)
The shortest exposure with mechanical shutters is about 14,000 second. Special high-speed shutter systems are magneto-optical, electro-optical, or electronic. A magneto-optical shutter (Faraday shutter) consists of a glass cylinder placed inside a magnetic coil between two crossed polarizing filters; so long as the filters remain crossed, virtually no light......
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magneto-sonic wave (physics)
...propagates parallel to the magnetic field at a speed roughly equal to the average thermal velocity of the ions. Perpendicular to the magnetic field a different type of longitudinal wave called a magnetosonic wave can occur....
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magnetoelectronics (electronics)
Spintronics refers to electronic devices that perform logic operations based on not just the electrical charge of carriers but also their spin. For example, information could be transported or stored through the spin-up or spin-down states of electrons. This is a new area of research, and issues include the injection of spin-polarized carriers, their transport, and their detection. The role of......
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magnetoencephalography (imaging technique)
imaging technique that measures the weak magnetic fields emitted by neurons. An array of cylinder-shaped sensors monitors the magnetic field pattern near the patient’s head to determine the position and strength of activity in various regions of the brain. In contrast with other imaging techniques, MEG can characterize rapidly changin...
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magnetofluid mechanics (physics)
the description of the behaviour of a plasma, or, in general, any electrically conducting fluid in the presence of electric and magnetic fields....
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magnetogram (geophysics)
...Typical scale factors for such observatories correspond to 2–10 nanoteslas per millimetre vertically and 20 millimetres per hour horizontally. A print of the developed negative is called a magnetogram....
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magnetohydrodynamic instability (physics)
...each type of configuration. Various types of instabilities can occur in plasma. These lead to a loss of plasma and a catastrophic decrease in containment time. The most important of these is called magnetohydrodynamic instability. Although an equilibrium state may exist, it may not correspond to the lowest possible energy. The plasma, therefore, seeks a state of lower potential energy, just as....
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magnetohydrodynamic power generator (physics)
any of a class of devices that generate electric power by means of the interaction of a moving fluid (usually an ionized gas or plasma) and a magnetic field. Magnetohydrodynamic (MHD) power plants offer the potential for large-scale electrical power generation with reduced impact on the environment. Since 1970, several countries have undertaken MHD research pr...
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magnetohydrodynamic wave (physics)
...the magnitude and the direction of Earth’s magnetic field vary erratically, occurs between 10 and 13 Earth radii toward the Sun. This disturbed region is thought to be caused by the production of magnetohydrodynamic shock waves, which in turn are caused by high-velocity solar wind particles. Ahead of this bow shock boundary, toward the Sun, is the undisturbed solar wind....
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magnetohydrodynamics (physics)
the description of the behaviour of a plasma, or, in general, any electrically conducting fluid in the presence of electric and magnetic fields....
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magnetometer (instrument)
instrument for measuring the strength and sometimes the direction of magnetic fields, including those on or near the Earth and in space. Magnetometers are also used to calibrate electromagnets and permanent magnets and to determine the magnetization of materials....
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magnetomotive force (physics)
The magnetic flux is analogous to the electric current. The magnetomotive force, mmf, is analogous to the electromotive force and may be considered the factor that sets up the flux. The mmf is equivalent to a number of turns of wire carrying an electric current and has units of ampere-turns. If either the current through a coil (as in an electromagnet) or the number of turns of wire in the coil......
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magneton (physics)
unit of magnetic moment (the product of a magnet’s pole strength and the distance between its poles) used in the study of subatomic particles. The Bohr magneton, named for the 20th-century Danish physicist Niels Bohr, is equal to about 9.273 × 10-21 erg per gauss per particle. The nuclear magneton, calculated using the mass of the pro...
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magnetopause (atmospheric science)
...escaping from Earth’s gravity is comparable to the opposing pressure associated with the solar wind. This equilibrium region, with a characteristic thickness of 100 km (60 miles), is called the magnetopause and marks the outer boundary of the magnetosphere. The lower boundary of the magnetosphere is several hundred kilometres above Earth’s surface....
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magnetopause current (geomagnetic field)
Farther still from the Earth, at about 10 Re along the Earth–Sun line, is yet another current system that affects the surface field and profoundly changes the nature of the Earth’s field in space. This system is called the magnetopause current, or Chapman-Ferraro current system for the English physicist Sydney Chapman and his student V.C.A. Ferraro, who first suggested its...
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magnetophone (electronics)
Magnetic tape was initially designed for sound recording. German engineers developed an audio tape recording machine called the magnetophone during World War II. U.S. and British researchers adopted the basic design of this device to create a magnetic tape recorder capable of high-quality sound reproduction in the late 1940s. Within a decade magnetic tape supplanted phonograph records for radio......
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magnetoreception (physiology)
Much interest has been shown in various animals’ ability to sense the Earth’s magnetic field. It has been demonstrated that birds and fish use magnetoreception in migration, and theories to explain why cetaceans beach themselves in mass strandings (see below) have included magnetic detection. Although magnetite has been found in some skulls of the common dolphin (Delphinu...
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magnetoresistance (physics)
...The process of epitaxy is general, however, and so can occur for other classes of materials, such as metals and oxides, which have been used since the 1980s to create materials that display giant magnetoresistance (a property that has been used to produce higher-density digital storage devices)....
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magnetoresistive random-access memory (electronics)
Another approach to information storage that is dependent on designing nanometre-thick magnetic layers is under commercial development. Known as magnetic random access memory (MRAM), a line of electrically switchable magnetic material is separated from a permanently magnetized layer by a nanoscale nonmagnetic interlayer. A resistance change that depends on the relative alignment of the fields......
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magnetosheath (atmospheric science)
The magnetosheath, a region of magnetic turbulence in which both the magnitude and the direction of Earth’s magnetic field vary erratically, occurs between 10 and 13 Earth radii toward the Sun. This disturbed region is thought to be caused by the production of magnetohydrodynamic shock waves, which in turn are caused by high-velocity solar wind particles. Ahead of this bow shock boundary,.....
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magnetosonic wave (physics)
...propagates parallel to the magnetic field at a speed roughly equal to the average thermal velocity of the ions. Perpendicular to the magnetic field a different type of longitudinal wave called a magnetosonic wave can occur....
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magnetosphere (atmospheric science)
region in the atmosphere where magnetic phenomena and the high atmospheric conductivity caused by ionization are important in determining the behaviour of charged particles....
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magnetospheric convection (atmospheric science)
...earthward. The field lines cannot return along the same path. Instead, they return through the interior of the Earth’s field. The motion of these closed field lines in two closed loops is called magnetospheric convection. This mechanism, together with the more important one due to reconnection, produces the tail current system....
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magnetospheric substorm (atmospheric science)
Magnetospheric substorm is the name applied to the collection of processes that occur throughout the magnetosphere at the time of an auroral and magnetic disturbance. The term substorm was originally used to signify that the processes produce an event, localized in time and space, which is distinct from a magnetic storm. During a typical three-hour substorm, the......
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magnetostatic field (physics)
Around a permanent magnet or a wire carrying a steady electric current in one direction, the magnetic field is stationary and referred to as a magnetostatic field. At any given point its magnitude and direction remain the same. Around an alternating current or a fluctuating direct current, the magnetic field is continuously changing its magnitude and direction....
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magnetostatics (physics)
...electricity as a mathematical science during the latter half of the 18th century. He transformed Priestley’s descriptive observations into the basic quantitative laws of electrostatics and magnetostatics. He also developed the mathematical theory of electric force and invented the torsion balance that was to be used in electricity experiments for the next 100 years. Coulomb used the......
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magnetostriction (physics)
change in the dimensions of a ferromagnetic material, such as iron or nickel, produced by a change in the direction and extent of its magnetization. An iron rod placed in a magnetic field directed along its length stretches slightly in a weak magnetic field and contracts slightly in a strong magnetic field. Mechanically stretching and compressing a magnetized...
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magnetostrictive transducer (instrument)
...including drying, ultrasonic cleaning, and injection of fuel oil into burners. Electromechanical transducers are far more versatile and include piezoelectric and magnetostrictive devices. A magnetostrictive transducer makes use of a type of magnetic material in which an applied oscillating magnetic field squeezes the atoms of the material together, creating a periodic change in the......
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magnetotail current (atmospheric science)
Radially outward near local midnight rather than at local noon, there is an entirely different current system. Beginning at approximately 10 Re and extending well beyond 200 Re is the tail current system. This current is from dawn to dusk in the same direction as the ring current on the nightside of the Earth. In fact, it is produced by the same mechanism except that, in......
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magnetotelluric method (geophysics)
...lightning strikes) and bombardment of the upper atmosphere by the solar wind—a radial flow of protons, electrons, and nuclei of heavier elements emanating from the outer region of the Sun. Magnetotelluric methods measure orthogonal components of the electric and magnetic fields induced by these natural currents. Such measurements allow researchers to determine resistivity as a function.....
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magnetron (electronics)
diode vacuum tube consisting of a cylindrical (straight wire) cathode and a coaxial anode, between which a dc (direct current) potential creates an electric field. A magnetic field is applied longitudinally by an external magnet. Connected to a resonant line, it can act as an oscillator. Magnetrons are capable of generating extremely high frequencies and also short bursts of very high power. They...
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Magnificat (biblical canticle)
in Christianity, the hymn of praise by Mary, the mother of Jesus, found in Luke 1:46–55 and incorporated into the liturgical services of the Western churches (at vespers) and of the Eastern Orthodox churches (at the morning services). Though some scholars have contended that this canticle was a song of Elizabeth (the wife of Zechariah and the mother of John the Baptist), ...
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magnification (optics)
in optics, the size of an image relative to the size of the object creating it. Linear (sometimes called lateral or transverse) magnification refers to the ratio of image length to object length measured in planes that are perpendicular to the optical axis. A negative value of linear magnification denotes an inverted image. Longitudinal magnification denotes the factor by which an image increases...
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Magnificent Ambersons, The (work by Tarkington)
...classic film Citizen Kane (1941), which portrayed the life of a newspaper magnate (suggestive of William Randolph Hearst, who sought to ban the movie), and The Magnificent Ambersons (1942), a screen version of Booth Tarkington’s novel of the same name. Welles directed and starred in The Stranger (1946), ......
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Magnificent Cuckold, The (work by Crommelynck)
...including such plays as Nous n’irons plus au bois (1906; “We’ll Not Go to the Woods Anymore”), Crommelynck won international honours with his play Le Cocu magnifique (The Magnificent Cuckold). First produced in Paris in 1920, it was revived many times. It is one of the few French-language plays from this period to have retained its appeal. The pl...
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magnificent frigate bird (bird)
The largest species (to about 115 cm [45 inches]) is the magnificent frigate bird, Fregata magnificens, found on both coasts of America, the Caribbean Sea, and Cape Verde. The great and lesser frigate birds, F. minor (see photograph) and F. ariel, breed on islands worldwide....
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Magnificent Magyars (Hungarian football team)
...States at the World Cup finals in Brazil. Most devastating were later, crushing losses to Hungary: 6–3 in 1953 at London’s Wembley Stadium, then 7–1 in Budapest a year later. The “Magnificent Magyars” opened English eyes to the dynamic attacking and tactically advanced football played on the Continent and to the technical superiority of players such as Ferenc....
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Magnificent Obsession (film by Sirk)
...Hudson graduated from bit parts to larger roles in a succession of westerns and adventure films, and he completed some 28 films in six years. He played a leading role in Douglas Sirk’s tearjerker Magnificent Obsession (1954) as a repentant scoundrel who selflessly dedicates himself to the woman he accidentally blinded. The film established Hudson as a star, and he went on to play....
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Magnificent Seven, The (American film)
In the early 1960s, McQueen attained stardom when he appeared in two action films directed by John Sturges. The first of these was the western The Magnificent Seven (1960), in which he starred with Yul Brynner and Charles Bronson as defenders of a Mexican village. The second action film to refine McQueen’s image was The Great Escape (1963), in which he portrayed an allied capt...
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Magnifico, il (Italian banker)
The first member of the family to win more than local eminence was Agostino Chigi, “il Magnifico” (c. 1465–1520), a merchant prince who, as a banker in Rome, developed one of the richest business houses in Europe, lending money to popes, administering church revenue, and spending lavishly on display and the patronage of artists and writers. It was he who built the......
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magnifier (microscope)
A magnifier permits the user to place the eye close to an object of interest and retain a focused image. The closer the object is to the eye, the larger the angle that it subtends at the eye, and thus the larger the object appears. If an object is brought too close, however, the eye can no longer form a clear image. The use of the magnifying lens between the observer and the object enables the......
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magnifying power (optics)
The magnifying power, or extent to which the object being viewed appears enlarged, and the field of view, or size of the object that can be viewed, are related by the geometry of the optical system. A working value for the magnifying power of a lens can be found by dividing the least distance of distinct vision by the lens’ focal length, which is the distance from the lens to the plane at w...
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Magnitogorsk (Russia)
city, Chelyabinsk oblast (province), western Russia, on both banks of the Ural River. It was founded in 1929 to exploit the rich magnetite iron ore of Mt. Magnitnaya, just east of the city. The gigantic iron- and steelworks, several times enlarged, was one of the world’s largest in 1975, with a steel capacity of about 15,000,000 tons annually. By then local ores were nearing exhaust...
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magnitude (astronomy)
in astronomy, measure of the brightness of a star or other celestial body. The brighter the object, the lower the number assigned as a magnitude. In ancient times, stars were ranked in six magnitude classes, the first magnitude class containing the brightest stars. In 1850 the English astronomer Norman Robert Pogson proposed the system presently in use. One magnitude is defined ...
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magnitude (mathematics)
...significant conceptually, he set aside Viète’s principle of homogeneity, showing by means of a simple construction how to represent multiplication and division of lines by lines; thus, all magnitudes (lines, areas, and volumes) could be represented independently of their dimension in the same way....
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magnitude, earthquake (geology)
Earthquake magnitude is a measure of the “size,” or amplitude, of the seismic waves generated by an earthquake source and recorded by seismographs. (The types and nature of these waves are described in the section Seismic waves.) Because the size of earthquakes varies enormously, it is necessary for purposes of comparison to compress the range of wave amplitudes measured on......
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magnitude-frequency analysis (hydrology)
...streams, in contrast to the long durations of flood waves far downstream, combine with analytical studies to suggest, however, that percentage frequency is in some respects an unsuitable measure. Magnitude–frequency analysis, setting discharge against time, is directly applicable in studies of hydraulic geometry and flood-probability forecasting....
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magnocellular layer (anatomy)
The LGN in humans contain six layers of cells. Two of these layers contain large cells (the magnocellular [M] layers), and the remaining four layers contain small cells (the parvocellular [P] layers). This division reflects a difference in the types of ganglion cells that supply the M and P layers. The M layers receive their input from so-called Y-cells, which have fast responses, relatively......
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Magnoli (altarpiece by Veneziano)
...executed in Florence. Its accurate perspective and the sculptural quality of the figures suggest he was influenced by Masaccio. The second work is an altarpiece for the Church of Santa Lucia dei Magnoli, usually called the St. Lucy altarpiece, which was probably painted about 1447. The central panel, the Virgin and Child with four saints (Uffizi, Florence), is one of the outstanding......
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magnolia (plant)
any member of the genus Magnolia (family Magnoliaceae; order Magnoliales), about 225 species of trees and shrubs native to North and South America, the Himalayas, and East Asia. They are valued for their large and fragrant white, yellow, pink, or purple flowers and frequently handsome leaves and conelike fruits. Some are important garden ornamentals; others are local timber sources. They ha...
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Magnolia (Arkansas, United States)
city, seat (1853) of Columbia county, southwestern Arkansas, U.S. It is on the West Gulf Coastal Plain between Texarkana and El Dorado, about 80 miles (129 km) northeast of Shreveport, Louisiana. Founded in 1853, it was named for the southern magnolia, or laurel, tree (Magnolia grandiflora), native to Arkansas. It evolved as a cotton town and a farm mar...
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Magnolia (plant)
any member of the genus Magnolia (family Magnoliaceae; order Magnoliales), about 225 species of trees and shrubs native to North and South America, the Himalayas, and East Asia. They are valued for their large and fragrant white, yellow, pink, or purple flowers and frequently handsome leaves and conelike fruits. Some are important garden ornamentals; others are local timber sources. They ha...
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Magnolia × soulangeana (magnolia hybrid)
Many of the cultivated magnolias are hybrids. Probably the most widely cultivated of these is Magnolia × soulangeana (saucer magnolia), a spreading deciduous shrub with leaves that measure up to 15–20 cm (6–8 inches) long. Its flowers appear in early spring before the leaves, and this flowering continues after the leaves have developed. The flowers are typically....
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Magnolia acuminata (plant)
...It is cultivated in almost all temperate regions of the world, and it flowers five to seven years after planting. Another cultivated magnolia native to the United States is the M. acuminata (yellow cucumber tree), which grows in open woods in the Appalachian region, Ozark Mountains, and the Ohio and Mississippi river valleys. M. acuminata derives its popular name from its yellow.....
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Magnolia ashei (plant)
...Magnolia grandiflora (bull bay, or Southern magnolia), for example, grows in forests from southern Virginia to eastern Texas and extends into the West Indies. Another American species, M. ashei, however, is found only in a few counties in Florida....
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Magnolia champaca (plant)
Asian tree of the magnolia family (Magnoliaceae). Lustrous leaved, pyramidal, and about 30 metres (100 feet) tall, the mature plant bears fragrant, star-shaped yellow flowers, which are the source of champac perfume and of a yellow dye. It is often grown as a boulevard tree in the tropics and is frequently planted on Hindu temple grounds because it is consider...
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Magnolia compressa (plant)
...its long stalk. Champac wood takes a good polish and is used for making boats, drums, and religious images. In India, however, where it is revered, the tree is rarely cut. A related species, Magnolia compressa, is a 12-metre (39-foot) Japanese tree with 2.5-cm (1-inch) fragrant yellow flowers....
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magnolia family (plant family)
magnolia family of the order Magnoliales that contains 7 genera and 227 species, including many handsome, fragrant-flowering trees and shrubs. Most have simple leaves and an elongated conelike floral axis with flowers that have six tepals (sepals and petals that are not distinctly different), many spirally arranged stamens, and one, two, or many carpels (female reproductive structures). The seeds ...
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Magnolia Flag (Mississippi history)
...of Secession prior to joining the Confederate States of America. The blue-and-white flag became known throughout the South as the Bonnie Blue Flag. On January 26, 1861, Mississippi adopted the Magnolia Flag, featuring the native tree on a white field; the canton was blue with a central white star, thus incorporating the Bonnie Blue design. The Magnolia Flag seems not to have been used......
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Magnolia grandiflora (plant)
...species are found in the temperate southeastern United States, Central America, northern South America, and Brazil. Many species of Magnolia are cultivated; Magnolia grandiflora (bull bay, or Southern magnolia), for example, grows in forests from southern Virginia to eastern Texas and extends into the West Indies. Another American species, M. ashei, however, is found only in a few...
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Magnolia Manor (historical building, Cairo, Illinois, United States)
...manufacture of polyurethane foam and pet products. Notable attractions include the Custom House (1872), which is now a local museum, and the mansions along “Millionaire’s Row,” including Magnolia Manor (1869), a five-story Italianate building. Fort Defiance State Park, site of the Civil War garrison, is just south; Mound City National Cemetery, just north of Cairo, contains...
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