- Micropterus salmoides (fish)
black bass: Two of them, the largemouth and smallmouth basses (M. salmoides and M. dolomieu), have been introduced in other countries and are prized as hard-fighting game fishes.
- micropyle (plant anatomy)
angiosperm: Ovules: …a small opening called the micropyle at the top. In angiosperms the presence of two integuments is plesiomorphic (unspecialized), and one integument is apomorphic (derived). A single large megasporocyte arises within the nucellus near the micropyle and undergoes meiotic division, resulting in a single linear tetrad of megaspores. Three of…
- micropyle (insect anatomy)
insect: Reproductive system: …chorion is also pierced by micropyles, fine canals that permit entry of one or more spermatozoa for fertilization. As the egg passes down the oviduct before egg laying, the micropyles come to lie opposite the duct of the spermatheca; at this stage fertilization occurs. Eggs must be waterproof to prevent…
- Microraptor (dinosaur)
dromaeosaur: …is debate as to whether Microraptor, the smallest and most birdlike dinosaur known, is a dromaeosaur or a troodontid. Only about the size of a crow, Microraptor appears to have possessed feathers. The single specimen was discovered in China in 2000 from deposits dating to the Early Cretaceous.
- microrecord
microform, any process, photographic or electronic, for reproducing printed matter or other graphic material in a much-reduced size, which can then be re-enlarged by an optical apparatus for reading or reproduction. Microform systems provide durable, extremely compact, and easily accessible file
- microregion (housing)
Kyiv: City layout: The neighbourhood units, known as microregions, consist of groupings of apartment buildings housing 2,500 to 5,000 people, together with basic services, local shops, a health centre, cinema, and primary school. Since the late 1960s the apartment buildings have usually been of 12 to 20 stories and of prefabricated construction. Most…
- microreproduction
microform, any process, photographic or electronic, for reproducing printed matter or other graphic material in a much-reduced size, which can then be re-enlarged by an optical apparatus for reading or reproduction. Microform systems provide durable, extremely compact, and easily accessible file
- microRNA (biochemistry)
Doting on Dodder: Doting on Dodder transcript: …passes what are known as microRNAs back to the host plant. These little pieces of RNA, genetic material, are only a few nucleotides long, but they seem to regulate the expression of host genes in a very direct way. Usually when a plant is injured, a mechanism similar to blood…
- Microryzomys (rodent)
rice rat: … (Oecomys), dark rice rats (Melanomys), small rice rats (Microryzomys), and pygmy rice rats (Oligoryzomys), among others. All belong to the subfamily Sigmodontinae of the “true” mouse and rat family Muridae within the order Rodentia.
- Microsarcops cinereus (bird)
lapwing: Others are the gray-headed lapwing (Microsarcops cinereus), of eastern Asia, and the long-toed lapwing (Hemiparra crassirostris), of Africa.
- microsatellite DNA (biochemistry)
heredity: Repetitive DNA: Microsatellite DNA is composed of tandem repeats of two nucleotide pairs that are dispersed throughout the genome. Minisatellite DNA, sometimes called variable number tandem repeats (VNTRs), is composed of blocks of longer repeats also dispersed throughout the genome. There is no known function for satellite…
- microsaur (fossil amphibian)
amphibian: Annotated classification: †Order Microsauria (microsaurs) Lower Pennsylvanian to Middle Permian. Lepospondylous vertebrae, i.e., spool-shaped bony cylinder around the notochord. †Subclass Temnospondyli (temnospondyls) Upper Mississippian to Middle Cretaceous. Vertebral centrum of large intercentrum and pair of small
- Microsauria (fossil amphibian)
amphibian: Annotated classification: †Order Microsauria (microsaurs) Lower Pennsylvanian to Middle Permian. Lepospondylous vertebrae, i.e., spool-shaped bony cylinder around the notochord. †Subclass Temnospondyli (temnospondyls) Upper Mississippian to Middle Cretaceous. Vertebral centrum of large intercentrum and pair of small
- microsclere (zoology)
sponge: Mineral skeletons: All of the microscleres apparently are derived from a spherical type with many axons (polyaxon); the result is a series of star-shaped spicules, or asters, with various numbers of rays. Spicules with rays missing or reduced (called spheres, sterrasters, and discasters) often form a protective armour around the…
- microscope (instrument)
microscope, instrument that produces enlarged images of small objects, allowing the observer an exceedingly close view of minute structures at a scale convenient for examination and analysis. Although optical microscopes are the subject of this article, an image may also be enlarged by many other
- microscopic anatomy (biology)
histology: The terms histology and microscopic anatomy are sometimes used interchangeably, but a fine distinction can be drawn between the two studies. The fundamental aim of histology is to determine how tissues are organized at all structural levels, from cells and intercellular substances to organs. Microscopic anatomy, on the other…
- microscopic reversibility, principle of (physics)
principle of microscopic reversibility, principle formulated about 1924 by the American scientist Richard C. Tolman that provides a dynamic description of an equilibrium condition. Equilibrium is a state in which no net change in some given property of a physical system is observable; e.g., in a
- microscopic symptom (plant pathology)
plant disease: Symptoms: Microscopic disease symptoms are expressions of disease in cell structure or cell arrangement seen under a microscope. Macroscopic symptoms are expressions of disease that can be seen with the unaided eye. Specific macroscopic symptoms are classified under one of four major categories: prenecrotic, necrotic, hypoplastic,…
- Microscopium (astronomy)
Microscopium, constellation in the southern sky at about 21 hours right ascension and 35° south in declination. Its brightest star is Gamma Microscopii, with a magnitude of 4.7. The French astronomer Nicolas Louis de Lacaille formed this constellation in 1754; it represents a
- microscopy (instrument)
microscope, instrument that produces enlarged images of small objects, allowing the observer an exceedingly close view of minute structures at a scale convenient for examination and analysis. Although optical microscopes are the subject of this article, an image may also be enlarged by many other
- Microscripts, The (work by Walser)
Robert Walser: …2010 an English-language tribute book, The Microscripts, was published, containing colour illustrations, transcriptions, and translations of 25 short pieces by Walser written in the tiny script he perfected.
- microseism (seismology)
seismograph: Applications of the seismograph: …oscillations of the ground, called microseisms, that do not originate as earthquakes. The occurrence of some microseisms is related to storms at sea.
- Microserfs (novel by Coupland)
Douglas Coupland: The novel Microserfs (1995) had its origins in an assignment for Wired magazine during which Coupland observed employees of Microsoft Corporation in Redmond, Washington, U.S. Microserfs was his fictional account of the experience; it highlighted workers’ pursuit of meaning in a seemingly meaningless environment.
- microsleep (physiology)
sleep: Sleep deprivation: …to be associated with “microsleep”—momentary lapses into sleep. Changes in body chemistry and in workings of the autonomic nervous system sometimes have been noted during deprivation, but it has proved difficult either to establish consistent patterning in such effects or to ascertain whether they should be attributed to sleep…
- Microsoft Corporation (American company)
Microsoft Corporation is an American multinational technology company that has been a key player in the computer industry since its founding in 1975. Headquartered in Redmond, Washington, Microsoft initially gained dominance in the operating systems market during the 1980s and ’90s with MS-DOS and
- Microsoft Disk-Operating System (operating system)
MS-DOS, the dominant operating system for the personal computer (PC) throughout the 1980s. The acquisition and marketing of MS-DOS were pivotal in the Microsoft Corporation’s transition to software industry giant. American computer programmer Timothy Paterson, a developer for Seattle Computer
- Microsoft Edge (Internet browser)
browser: …Explorer and replaced it with Edge in 2015.
- Microsoft Encarta Multimedia Encyclopedia (encyclopedia)
Encarta, multimedia digital encyclopaedia produced by Microsoft Corporation (1993–2009). Initially a CD-ROM product, the Encarta brand later expanded to include an Internet-based incarnation and was bundled with other Microsoft products. The possibility of a digital encyclopaedia was first
- Microsoft Excel (software)
Microsoft Excel, spreadsheet application launched in 1985 by the Microsoft Corporation. Excel is a popular spreadsheet system, which organizes data in columns and rows that can be manipulated through formulas that allow the software to perform mathematical functions on the data. Lotus 1-2-3, first
- Microsoft Internet Explorer (Internet browser)
Internet Explorer (IE), World Wide Web (WWW) browser and set of technologies created by Microsoft Corporation, a leading American computer software company. After being launched in 1995, Internet Explorer became one of the most popular tools for accessing the Internet. There were 11 versions
- Microsoft PowerPoint (software)
Microsoft PowerPoint, virtual presentation software developed by Robert Gaskins and Dennis Austin for the American computer software company Forethought, Inc. The program, initially named Presenter, was released for the Apple Macintosh in 1987. In July of that year, the Microsoft Corporation, in
- Microsoft TerraServer (database)
James Nicholas Gray: …database technologies, Gray helped develop Microsoft TerraServer, a free searchable database of satellite images of the Earth’s surface, which went online in 1998, many years before the comparable Google Earth was launched. Beginning in 2002 Gray was also instrumental in developing SkySearch—released to the public in 2008 as the Microsoft…
- Microsoft Windows (operating system)
Microsoft Windows, computer operating system (OS) developed by Microsoft Corporation to run personal computers (PCs). Featuring the first graphical user interface (GUI) for IBM-compatible PCs, the Windows OS soon dominated the PC market. Approximately 90 percent of PCs run some version of Windows.
- Microsoft Word (software)
Microsoft Word, word-processor software launched in 1983 by the Microsoft Corporation. Software developers Richard Brodie and Charles Simonyi joined the Microsoft team in 1981, and in 1983 they released Multi-Tool Word for computers that ran a version of the UNIX operating system (OS). Later that
- Microsoft Worldwide Telescope (computer application)
James Nicholas Gray: …public in 2008 as the Microsoft Worldwide Telescope—which combines astronomical images from various sources into a free searchable and viewable application.
- microsome (cytology)
ribosome, particle that is present in large numbers in all living cells and serves as the site of protein synthesis. Ribosomes occur both as free particles in prokaryotic and eukaryotic cells and as particles attached to the membranes of the endoplasmic reticulum in eukaryotic cells. The small
- microsound (physics)
ultrasonics: Hypersound, sometimes called praetersound or microsound, is sound waves of frequencies greater than 1013 hertz. At such high frequencies it is very difficult for a sound wave to propagate efficiently; indeed, above a frequency of about 1.25 × 1013 hertz it is impossible for longitudinal…
- microsphere (glass)
industrial glass: Beads and microspheres: Solid glass beads and microspheres used in blast cleaners, shot peening, and reflective paints can be made simply by passing finely fritted glass through a hot flame. Hollow microspheres, used mostly as low-density fillers, may be produced by one of many processes. In one…
- microsporangium (plant anatomy)
plant: Heterosporous life histories: Microsporangia (male sporangia) produce microsporocytes (micromeiocytes) that yield microspores. Megasporangia (female sporangia) produce megasporocytes (megameiocytes) that yield megaspores. The sporangia may be borne in specialized structures such as sori in ferns, cones (strobili) in some pteridophytes and most gymnosperms, or flowers in angiosperms.
- microspore (plant anatomy)
spore: …form two kinds of spores: microspores, which give rise to male gametophytes, and megaspores, which produce female gametophytes.
- Microsporidia (fungus)
microsporidian, any parasitic fungus of the phylum Microsporidia (kingdom Fungi), found mainly in cells of the gut epithelium of insects and the skin and muscles of fish. They also occur in annelids and some other invertebrates. Infection is characterized by enlargement of the affected tissue.
- microsporidian (fungus)
microsporidian, any parasitic fungus of the phylum Microsporidia (kingdom Fungi), found mainly in cells of the gut epithelium of insects and the skin and muscles of fish. They also occur in annelids and some other invertebrates. Infection is characterized by enlargement of the affected tissue.
- microsporocyte (plant anatomy)
angiosperm: Anthers: These tissues are composed of microsporocytes, which are diploid cells capable of undergoing meiosis to form a tetrad (four joined cells) of haploid microspores. The microspores become pollen grains and may eventually separate.
- microsporophyll (plant anatomy)
gymnosperm: Pinophyta: …arrangement, reduced fertile leaves (the microsporophylls). On the lower surfaces of the microsporophylls are borne elongated microsporangia; two microsporangia per microsporophyll is common, but some genera have more. The ovulate cone, the megastrobilus, is more complex than the microstrobilus. The megastrobilus bears seeds on flattened dwarf branches, all parts of…
- microstate (politics)
micronation: Micronations are distinct from microstates, such as Liechtenstein or Vatican City, whose sovereignty over extremely small territories and populations is internationally recognized.
- Microstomum (flatworm genus)
planarian: …of others in the genus Microstomum and may remain attached to the parent for some time; chains formed of three or four buds sometimes occur. Because of their remarkable ability to regenerate lost parts, planarians are often used experimentally to study the process of regeneration.
- microstrainer
water supply system: Filtration: Microstrainers consist of a finely woven stainless-steel wire cloth mounted on a revolving drum that is partially submerged in the water. Water enters through an open end of the drum and flows out through the screen, leaving suspended solids behind. Captured solids are washed into…
- microstrobilus (plant anatomy)
gymnosperm: General features: …the male pollen cones, called microstrobili, contain reduced leaves called microsporophylls. Microsporangia, or pollen sacs, are borne on the lower surfaces of the microsporophylls. The number of microsporangia may vary from two in many conifers to hundreds in some cycads. Within the microsporangia are cells which undergo meiotic division to…
- Microstromatales (order of fungi)
fungus: Annotated classification: Order Microstromatales Parasitic on plants, some found in the nectar of orchids; some are nonteliosporic; some are anamorphic yeasts lacking septal pores; example genera include Microstroma, Sympodiomycopsis, and Volvocisporium. Order Tilletiales Parasitic on grasses (family Poaceae
- microstructure fabrication (science)
spectroscopy: Optical detectors: Microfabrication techniques developed for the integrated-circuit semiconductor industry are used to construct large arrays of individual photodiodes closely spaced together. The device, called a charge-coupled device (CCD), permits the charges that are collected by the individual diodes to be read out separately and displayed as…
- microsurgery (medicine)
microsurgery, the specialized surgical technique of observing through a compound microscope when operating on minute structures of the human body. Microsurgery has made possible significant advances in surgery on humans, especially in delicate operations on the inner ear, eye, brain, and nerve
- microsurgical epididymal sperm aspiration (medical procedure)
infertility: Treatment options: …in a procedure known as microsurgical epididymal sperm aspiration (MESA). Eggs that are successfully fertilized are placed in the woman’s uterus.
- MicroTAC (cell phone)
Motorola, Inc.: Consumer telecommunications business: …1989 the company introduced the MicroTAC flip cellular phone, which quickly became an international status symbol as well as a useful personal communications device. The overwhelming success of cellular telephony inspired the development of Iridium, a system of 66 small satellites deployed in low Earth orbit that enabled communications over…
- microtasimeter (instrument)
Thomas Edison: The electric light: …needs Edison devised a “microtasimeter” employing a carbon button. This was a time when great advances were being made in electric arc lighting, and during the expedition, which Edison accompanied, the men discussed the practicality of “subdividing” the intense arc lights so that electricity could be used for lighting…
- Microtatobiotes (formerly proposed taxon)
Microtatobiotes, a class name proposed earlier for the viruses and rickettsias, infective agents that grow and reproduce only inside living cells. The order Virales comprises the viruses of bacteria, plants, and animals. The order Rickettsiales comprises the rickettsias, somewhat larger parasites,
- microteiid (reptile family)
lizard: Annotated classification: Family Gymnophthalmidae (spectacled lizards or microteiids) Small lizards with relatively small limbs, reduced limbs, or no limbs. Restricted to the Neotropics. 38 genera with more than 160 species. Family Lacertidae (lacertids and wall lizards) Osteoderms absent, supratemporal
- microtektite (geology)
tektite: Microtektites of millimetre and smaller size, first discovered in 1968, exhibit wider variation in composition than the large tektites; e.g., their silica content can be as low as 50 percent, similar to that of terrestrial basalts. Microtektites have been found so far only in deep-sea…
- microthermal stream (hydrology)
river: Variation of stream regime: Microthermal regimes, which are influenced by snow cover, include winter minima and summer maxima resulting from snowmelt and convectional rain; alternatively, spring meltwater maxima are accompanied by secondary fall maxima that are associated with late-season thunder rain, or spring snowmelt maxima can be followed by…
- Microthyriales (order of fungi)
fungus: Annotated classification: Order Microthyriales (incertae sedis; not placed in any subclass) Saprotrophic or epiphytic on stems and leaves. Order Patellariales (incertae sedis; not placed in any subclass) Parasitic and saprotrophic; flask-shaped (perithecium-like) fruiting bodies; example genus is Patellaria. Order
- Microtityus fundorai (scorpion)
scorpion: Size range and diversity of structure: …the smallest scorpions, the Caribbean Microtityus fundorai, is 12 mm (0.5 inch). A few precursors of modern scorpions were comparative giants. Fossils of two species (Gigantoscorpio willsi and Brontoscorpio anglicus) measure from 35 cm (14 inches) to a metre (3.3 feet) or more, and an undescribed species is estimated to…
- microtome (instrument)
Wilhelm His: In 1865 His invented the microtome, a mechanical device used to slice thin tissue sections for microscopic examination. He was the author of Anatomie menschlicher Embryonen, 3 vol. (1880–85; “Human Embryonic Anatomy”), considered the first accurate and exhaustive study of the development of the human embryo.
- microtonal music
microtonal music, music using tones in intervals that differ from the standard semitones (half steps) of a tuning system or scale. In the division of the octave established by the tuning system used on the piano, equal temperament, the smallest interval (e.g., between B and C, F and F♯, A♭ and A)
- microtonality
microtonal music, music using tones in intervals that differ from the standard semitones (half steps) of a tuning system or scale. In the division of the octave established by the tuning system used on the piano, equal temperament, the smallest interval (e.g., between B and C, F and F♯, A♭ and A)
- Microtonus brevicollis (insect)
hymenopteran: Reproduction: …first generation of the braconid Microtonus brevicollis is parthenogenetic and parasitizes the adult form of the beetle Haltica amphelophaga. The second generation, however, lives in the larvae of the same beetle, and the females are impregnated by males. The occurrence of parthenogenesis is determined by a nutritional or hormonal factor…
- microtoponymy (linguistics)
name: Categories of names: …parts of forests) are called microtoponymy; names of streets, roads, and the like are called hodonymy; names of bodies of water, hydronymy; and names of mountains, oronymy. Additional terms are not generally used (though one occasionally hears words like chrematonymy—names of things).
- microtrauma (pathology)
joint disease: Degenerative joint disease: On the other hand, repetitive microtrauma (small injuries), such as that arising from heavy pneumatic drill vibrations or certain athletic activities, is more likely to do so. Lifting heavy weights has been implicated in some studies of spinal involvement. The first metatarsophalangeal (MTP) joint, located between the big toe and…
- microtriches (anatomy)
microvillus, any of numerous microscopic bristlelike protrusions that occur on the surface of a wide variety of cell types, including intestinal epithelial cells, neurons, photoreceptors (light-sensitive cells), and certain cells of the immune system, such as dendritic cells and lymphocytes.
- microtubule (biology)
microtubule, tubular structure of indefinite length, constructed from globular proteins called tubulins, which are found only in eukaryotic cells. Microtubules have several functions. For example, they provide the rigid, organized components of the cytoskeleton that give shape to many cells, and
- Microtus breweri (mammal)
meadow vole: …closest living relative is the beach vole (M. breweri) of Muskeget Island off the coast of Massachusetts, which evolved from mainland populations of the meadow vole only during the last 3,000 years. The genus Microtus contains about half of all vole species. Voles, lemmings, and the muskrat are all classified…
- Microtus ochrogaster (rodent)
cotton rat: …the native prairie vole (Microtus ochrogaster). These two rodents are similar in both appearance and behaviour, the cotton rat being the prairie vole’s larger-bodied ecological equivalent. Indeed, the meadow vole (M. pennsylvanicus), ranging from Alaska to the Eastern Seaboard, is also prolific and is the most abundant mammal in…
- Microtus pennsylvanicus (rodent)
meadow vole, (Microtus pennsylvanicus), one of the most common and prolific small mammals in North America. Weighing less than 50 grams (1.8 ounces), this stout vole is 15 to 20 cm (5.9 to 7.9 inches) long, including its short tail (3 to 6 cm). The dense, soft fur is chestnut-brown above and gray
- Microtus pinetorum (rodent)
woodland vole, (Microtus pinetorum), a small mouselike rodent of the eastern United States that is well adapted to burrowing, as reflected by its slender, cylindrical body, strong feet, and large front claws. The very small eyes and ears are hidden in short, dense molelike fur; prominent whiskers
- Microtus quasiater (rodent)
woodland vole: …closest living relative is the Jalapan pine vole (M. quasiater), which inhabits cool and wet forests of eastern Mexico in the states of San Luis Potosí and Oaxaca.
- Microvariability and Oscillations of Stars (Canadian orbiting telescope)
MOST, Canadian telescope that studied physical processes in stars and properties of extrasolar planets. MOST was launched on June 30, 2003, from Plestek, Russia, and was Canada’s first space telescope. It was a small spacecraft that weighed about 60 kg (130 pounds) and carried a telescope 15 cm (6
- microvilli (anatomy)
microvillus, any of numerous microscopic bristlelike protrusions that occur on the surface of a wide variety of cell types, including intestinal epithelial cells, neurons, photoreceptors (light-sensitive cells), and certain cells of the immune system, such as dendritic cells and lymphocytes.
- microvillus (anatomy)
microvillus, any of numerous microscopic bristlelike protrusions that occur on the surface of a wide variety of cell types, including intestinal epithelial cells, neurons, photoreceptors (light-sensitive cells), and certain cells of the immune system, such as dendritic cells and lymphocytes.
- microwave (physics)
microwave, electromagnetic radiation having a frequency within the range of 1 gigahertz to 1 terahertz (109–1012 cycles per second) and a wavelength between 1 mm and 1
- microwave (physics)
microwave, electromagnetic radiation having a frequency within the range of 1 gigahertz to 1 terahertz (109–1012 cycles per second) and a wavelength between 1 mm and 1
- microwave ablation (therapeutics)
lung cancer: Treatment: …treatment of lung cancer is microwave ablation, which relies on heat derived from microwave energy to kill cancer cells. Early studies in small subsets of patients have demonstrated that microwave ablation can shrink and possibly even eliminate some lung tumours.
- microwave absorptiometry
chemical analysis: Microwave absorptiometry: In a manner that is similar to that described for nuclear magnetic resonance spectrometry, electron spin resonance spectrometry is used to study spinning electrons. The absorbed radiation falls in the microwave spectral region and induces transitions in the spin states of the electrons.…
- microwave amplification by stimulated emission of radiation (physics)
maser, device that produces and amplifies electromagnetic radiation in the microwave range of the spectrum. The first maser was built by the American physicist Charles H. Townes. Its name is an acronym for “microwave amplification by stimulated emission of radiation.” The wavelength produced by a
- microwave diathermy (medicine)
diathermy: clinics: shortwave, ultrasound, and microwave. In shortwave diathermy, the part to be treated is placed between two condenser plates, and the highest temperature is concentrated in the subcutaneous tissues. Shortwave usually is prescribed as treatment for deep muscles and joints and is sometimes used to localize deep inflammatory disease.…
- microwave landing system
traffic control: New concepts: …continued expansion in use of microwave landing systems (MLS), which are replacing aging instrument landing system (ILS) equipment. The MLS is a more accurate and reliable contemporary technology.
- microwave monolithic integrated circuit (electronics)
integrated circuit: Monolithic microwave ICs: A special type of RFIC is known as a monolithic microwave IC (MMIC; also called microwave monolithic IC). These circuits usually run in the 2- to 100-GHz range, or microwave frequencies, and are used in radar systems, in satellite communications, and as…
- microwave oven
microwave oven, appliance that cooks food by means of high-frequency electromagnetic waves called microwaves. A microwave oven is a relatively small, boxlike oven that raises the temperature of food by subjecting it to a high-frequency electromagnetic field. The microwaves are absorbed by water,
- microwave radio (computer science)
computer: Networking: Microwave radio also carries computer network signals, generally as part of long-distance telephone systems. Low-power microwave radio is becoming common for wireless networks within a building.
- microwave region (physics)
microwave, electromagnetic radiation having a frequency within the range of 1 gigahertz to 1 terahertz (109–1012 cycles per second) and a wavelength between 1 mm and 1
- microwave sintering
advanced ceramics: Rapid heating: …heating are plasma sintering and microwave sintering. Plasma sintering takes place in an ionized gas. Energetic ionized particles recombine and deposit large amounts of energy on the surfaces of the ceramic being sintered. Extremely high sintering rates have been achieved with this method. In microwave sintering, electromagnetic radiation at microwave…
- microwave spectroscopy
spectroscopy: Microwave spectroscopy: For diatomic molecules the rotational constants for all but the very lightest ones lie in the range of 1–200 gigahertz (GHz). The frequency of a rotational transition is given approximately by ν = 2B(J + 1), and so molecular rotational spectra will exhibit…
- microworld (computer science)
artificial intelligence: Microworld programs: To cope with the bewildering complexity of the real world, scientists often ignore less relevant details; for instance, physicists often ignore friction and elasticity in their models. In 1970 Marvin Minsky and Seymour Papert of the MIT AI Laboratory proposed that, likewise, AI…
- micrurgy (medicine)
microsurgery, the specialized surgical technique of observing through a compound microscope when operating on minute structures of the human body. Microsurgery has made possible significant advances in surgery on humans, especially in delicate operations on the inner ear, eye, brain, and nerve
- Micruroides euryxanthus
coral snake: The Arizona coral snake (Micruroides euryxanthus) is a small (40–50-cm) inhabitant of the American Southwest.
- Micrurus (snake genus)
coral snake: Micrurus has the most species of the New World coral snake genera, about 80. They range from the southern United States to Argentina. Only two species, however, live in the United States. The eastern coral snake, or harlequin snake (Micrurus fulvius), which lives in the…
- Micrurus fulvius (reptile)
coral snake: The eastern coral snake, or harlequin snake (Micrurus fulvius), which lives in the southeastern U.S., is about 1 metre (3.3 feet) long and has wide red and black rings separated by narrow rings of yellow. The Arizona coral snake (Micruroides euryxanthus) is a small (40–50-cm) inhabitant…
- Mictacea (crustacean)
crustacean: Annotated classification: Order Mictacea Holocene; no functional eyes; carapace forms small lateral folds covering bases of mouthparts and maxillipeds; all trunk segments free; antennules biramous; thoracic limbs with exopods; abdominal appendages reduced, uniramous; 2.7–3.5 mm; deep-sea or in marine caves; 2 species. Order Tanaidacea Permian to present; carapace…
- Mictecacihuatl (Aztec deity)
Day of the Dead: Led by the goddess Mictecacihuatl, known as “Lady of the Dead,” the celebration lasted a month. After the Spanish arrived in Mexico and began converting the native peoples to Roman Catholicism, the holiday was moved to coincide with All Saints’ Day and All Souls’ Day (November 1 and 2,…
- mictic egg (biology)
reproductive behaviour: Flatworms and rotifers: …the male population increases, most mictic eggs become fertilized, resulting in the production of a heavy-shelled dormant egg with much yolk. The dormant egg survives the winter and gives rise to the amictic females of the next spring. Thus, despite the many generations produced in the summer by so-called sexual…
- Mictlantecuhtli (Aztec deity)
Mictlantecuhtli, Aztec god of the dead, usually portrayed with a skull face. With his wife, Mictecacíhuatl, he ruled Mictlan, the underworld. The souls of those whose manner of death failed to call them to various paradises (i.e., for those dead by war, sacrifice, childbirth, drowning, lightning,
- micturition (physiology)
urination, the process of excreting urine from the urinary bladder. Nerve centres for the control of urination are located in the spinal cord, the brainstem, and the cerebral cortex (the outer substance of the large upper portion of the brain). Both involuntary and voluntary muscles are involved.
- Micu-Klein, Ion Inochentie (Romanian bishop)
Romania: Romanians in Transylvania: …under the guidance of Bishop Ion Inochentie Micu-Klein (in office 1729–51). In the second half of the 18th century, Micu-Klein’s disciples strove to achieve recognition of the Romanians as a constituent nation of Transylvania. They also elaborated a modern, ethnic idea of nationhood based on the theory of Roman origins…