11/10/2013 20:52:00 PM
In biology, a repressor is a protein which blocks an operon by binding to an operator gene, inhibiting the expression of one or more genes.
11/08/2013 16:28:00 PM
The source or origin of Missouri River is located in Montana's Rocky Mountains. Thus, the melting snow of these mountain summits gives rise to the longest river in North America. Being the Mississippi River's main tributaries, it is 2,565 mile long a
08/30/2013 20:15:00 PM
Measuring blood pressure is very important preventive medical procedure to check for hipertension or hypotension. It is measured using an air-pumped sphygmomanometer and a stethoscope.How to measure blood pressure in the right professional way
08/28/2013 21:29:00 PM
Someone has hypotension when his blood pressure drops down below normal levels, which is 120 - 70mm for the sistolic and diastolic respectively. Symptoms are somnolence (sleepiness), fatigue, and headache, but if the blood pressure is too low, one fe
08/27/2013 20:52:00 PM
Hypertension is a medical condition characterized by chronic high blood pressure, whose measurement is above 130mm for the sistolic (high) and 80mm for the diastolic, with some patient reaching the 200--110mm for both. If not treated, hypertension ca
08/26/2013 21:11:00 PM
The axillary artery is the origin of all the arteries of the arm. It changes its name for brachial artery after it has crossed the armpit into the upper arm, running behind the teres mayor muscle. The brachial artery goes down along the inner side of
08/24/2013 21:11:00 PM
Scoliosis is a medical condition characterized by an abnormal side-to-side arching deformation of the spinal column, which may cause muscle fatigue and pain in the back. In severe cases of scoliosis, a noticeable asymmetry can be seen when looked fro
08/23/2013 17:32:00 PM
Necrosis caused by ischemia is the death of body tissue by lack of oxygen-rich blood supply, due to occlusion (blockage) of one or several blood vessels or to exposure to extreme low temperatures, since cold weather makes small arteries and veins to
08/16/2013 10:31:00 AM
Myofibrillar degeneration is a heart condition characterized by a series of lesions scattered throughout the myocardium (heart muscle) or a lesion surrounding infarcts necrosis. Under the electronic microscope, dense clusters of damaged myofilaments
08/14/2013 19:54:00 PM
Fibromyalgia is a medical condition marked by chronic pain and stiffness in joints and muscles, sleep disturbances, and fatigue, but there is no inflammation. The cause of this syndrome is unknown. Treatment consists of analgesics (pain killers).
08/13/2013 17:21:00 PM
There are one thousand (1,000) micrometers (um) in a milimeter (mm), that is to say 1 um is equal to 0,001 mm or 1/1000th of one mm, and one million (1,000,000) in a meter.
07/09/2013 18:18:00 PM
Bone resorption is loss of bone tissue induced either by physiological or pathologic means. Although it can lead to bone mass loss and weakening of bone structures, when it is caused by a disease, resorption in a healthy person is an important physio
06/20/2013 19:27:00 PM
A vertebra is any of the 31 bone segments that make up the spinal column. Each one of them has a ring-like hole at the center through which the spinal cord runs. The thoracic vertebrae have three protruding bony projections.
06/18/2013 20:47:00 PM
An osteoclast is a multinucleated giant cell found in osseous tissue and is associated with bone resorption (breaking down of bone). It has between three and several nuclei and many lysosomes.
06/17/2013 23:46:00 PM
Epiphysis is the wider and thicker end of a long bone (femur, for example), which develops from a secondary ossification center, separated at the beginning from the main bone body by a cartilaginous disk, but later gets fused into the main bone shaft
06/16/2013 21:04:00 PM
The foramen magnum is the hole at the base of the cranium the spinal cord runs through to become the medulla oblongata once inside the skull. Anatomically, it is situated in the inferior part of the occipital bone. The vertebral arteries and the acce
06/15/2013 19:03:00 PM
The vertebral column is made up of 31 separate bones called vertebrae. These interlock to form a strong flexible column, through which the spinal cord runs. They short pieces of bone, with ring-like hole which encloses the spinal cord. Except for the
06/10/2013 22:42:00 PM
Ischemia is a sharp drop in the oxygen-rich blood flow in an organ tissue due to an occlusion or constriction of an artery, or one of its branches. This lack of blood supply to the tissue cells causes an area of necrosis (dead tissue) and the malfunc
06/08/2013 17:01:00 PM
An infarct is a dead tissue area in an organ caused by lack of blood supply. This ischemia (stoppage of blood flow) that leads to the death of tissue (necrosis) is caused by blockage or occlusion of an artery or an arterial branch. Infarcts usually o
06/06/2013 17:36:00 PM
A vascular spasm is a sudden tightening of blood vessel walls that strangles the blood blow, reducing or completely stopping it. As a result, sometimes a blood vessel could burst and cause a cerebral hemorrhage, or stroke, in the brain, or a heart at
06/04/2013 22:06:00 PM
Graphite is a soft native carbon in hexagonal form, which is found naturally in black to dark-grey masses with metallic luster. It is used in painting, coating, lubricants, and lead pencils.
06/03/2013 20:24:00 PM
Graphene is a one-atom-thick carbon layer arranged in a honeycomb-like two-dimensional structure, which looks like chicken wire. Derived from graphite, it is used to make detection devices, optical components, sensors, and protective coatings. It has
05/23/2013 18:33:00 PM
The Garden eel is a genus of the Congridae eels, which inhabits the Central Pacific sea waters. They thrive in colonies on sandy bottoms.
04/12/2013 12:10:00 PM
The source or origin of the Mississippi River is Lake Itasca, a 1.8-square-mile glacial lake in Clear Water county, central Minesota. This lake, in turn, is fed by Nicollet creek, Elk Lake outlet stream, and winter snowfall. Receiving high volume of
04/01/2013 21:11:00 PM
Convection is the transfer of heat within fluids through the flow of molecules in a circulatory pattern. It is due to the variation of density and the action of gravity.
03/28/2013 10:48:00 AM
The origin of the Nile River is Lake Victoria, situated on the Uganda-Tanzania-Kenya border, in east central Africa. The headstream, or main river, that feeds this lake is Kagera River. As it flows northward, the Nile River receives three times its v
03/23/2013 21:16:00 PM
The Andean Volcanic Belt is a chain of active volcanos that stretches along the Andes Mountain Range, from Colombia to Chile. It is composed of four volcanic zones; the first one begins with Nevado del Ruiz volcano in Colombia and ends in Ecuador; th
03/20/2013 23:20:00 PM
The Andes mountain range originated by the collision of the Nazca tectonic plate against the South American plate 45 million years ago, during the Tertiary. It was the result of a collision of plates, with the Nazca plate sliding underneath the South
03/15/2013 20:10:00 PM
The Marañón River originates at the confluence of Nupe and Lauricocha Rivers, near the town of Rondos, at 5,800 m of altitude in the Andes Range, Peru. With a course of 1,100 miles, it ends at a point where it flows into the Ucayali River, to becom
03/12/2013 21:39:00 PM
Arising in the Parima mountains, the Orinoco River is a 1,500-mile long river that flows across Venezuela and into the Atlantic Ocean. Its main tributaries are Apure, Arauca, Atabaupa, Cauro, etc. Among the fish living in its waters is piranha. Croco
03/11/2013 23:02:00 PM
The origin of Amazon River is the Lauricocha River, which springs from melting water from an Andes Range glacier at 5,800 m of altitude, northeast of Lima, Peru. Having run for 85 kilometers, Lauricocha River meets Nupe River to form Marañón River,
03/08/2013 20:30:00 PM
The Baldwin 0-6-6-0 1000 was a diesel-electric locomotive designed and manufactured by Baldwin Locomotive Works from 1945, for the Soviet State-owned Railways. It was powered by an 8-cylinder 1000 hp diesel engine that reached 60 mph (97km/h). It had
03/07/2013 19:34:00 PM
The M62 is a Russian V12 diesel engine locomotive, delivering 1,974 hp and capable of developing 62 miles per hour (100 km/h). It was made by the State-run Voroshilovgrad Locomotive Factory, from 1965 to 1994, to draw heavy freight trains on standard
03/04/2013 21:31:00 PM
Designed by George and Robert Stephenson, the Adler was a British-made German steam locomotive, which entered service in 1835, running on standard gauge tracks, from Nurumberg to Früh and back, for the Bavarian Ludwig Railway. The firebox used coke
03/03/2013 21:44:00 PM
The GWR 6800 Grange Class was a steam locomotive model built by Great Western Railways between 1936 and 1939, used in England until the 1960s. It had a 4-6-0 configuration and drove on standard-gauge tracks (1.435 m). It used coal as fuel, running wi
03/01/2013 21:56:00 PM
A fire-tube boiler is a type of boiler used in steam locomotives in the 19th and first half of the 20th century. It consisted of a series of tubes running through water contained in a sealed vessel; hot gases from burning coal or wood in a firebox we
02/28/2013 13:33:00 PM
Anthracite is a mineral coal which burns almost without flame. Black, hard and brittle, it has a high degree of metamorphism. It is used to heat water in boilers to produce steam to propel turbines in power plants. In the past anthracite was the powe
02/26/2013 20:46:00 PM
Helium is an inert, very light, gaseous element, present in the Sun's atmosphere, some minerals, natural gas, etc. It also occurs as a radioactive decomposition product and is used as substitute for flammable gases in dirigible balloons. Symbol He; a
02/25/2013 20:11:00 PM
The Very Large Telescope array is a astronomical optical system that is composed of four telescopes, which are combined into an astronomical interferometer, which probes the celestial bodies and structures of the universe with higher resolution by me
02/24/2013 17:27:00 PM
The Archimedes' Principle is the law which establishes that a body immersed in a fluid is buoyed up by a force equal to the weight of the fluid displaced by the body. This upward force which pushed up the body is called "buoyant force". The body will
02/22/2013 20:51:00 PM
Neon is a chemically inert gaseous element, occurring in small amounts in the Earth's atmosphere. It is used mainly in orang-red tubular electrical discharge lamps. One liter of Neon, at 0ºC and at 760 millibars of pressure, weighs 0.9002 grams. Sym
02/21/2013 20:44:00 PM
Titanium is a dark-grey, very hard, light and corrosion-resistant metallic element, occurring combined with various minerals. It is used in metallurgy to remove oxygen and nitrogen from steel and to toughen it. Due to its lightness and hardness, tita
02/20/2013 14:57:00 PM
After more than 10 years of research, scientists of the Ohio State Universty have found a way to get energy from coal without burning it, avoiding and removing 99% of the pollution from this mineral through a process called coal-direct chemical loopi
02/18/2013 19:05:00 PM
Inertial mass is the mass of a body as determined by Newton's Second Law of Motion (the body's momentum), which states that "the acceleration of a falling body is inversely proportional to its inertial mass but directly proportional to its gravitatio
02/16/2013 09:03:00 AM
A meteoroid is any of the small celestial rocky bodies that drift in outer space and that are smaller in size than an asteroid. They are often remnants of comets or any other celestial object that got fragmented upon collision and became spacial debr
02/15/2013 11:51:00 AM
Also called minor planet, an asteroid is any of the thousands of small celestial bodies, measuring from 500 miles to less than one mile in diameter, that drift in outer space. In the Solar System, asteroids revolve about the Sun in orbits that lie mo
02/12/2013 20:52:00 PM
Metrology is the science of measures and weights. It establishes a ratio to another fixed quantity, length or weight called patron unit. For example, the meter is the patron unit of length in the metric system. Today, metrology is very important in s
02/09/2013 08:59:00 AM
Gallium is a rare, steely-gray, trivalent metallic element, which is used in high temperature thermometers because it has a high boiling point (1983ºC). Symbol Ga; atomic number 31; atomic weight 69.72.
02/08/2013 08:31:00 AM
The bacterium that causes gas gangrene is the Clostridium perfringens, which is a Gram-negative rod-shaped anaerobic bacterium (bacillus). It is found widely in nature: humid soil, stagnant water, milk, and the human and animal intestinal tract. Cont
02/07/2013 14:10:00 PM
The origin of mammals go back to Protungulatum donnae, an ant-eating animal that had the size of a rat and that lived in the late Cretaceous, about 145 million years ago. The ancestor of mammals was an archaic warm-blooded ungulate with a long furry
02/06/2013 19:37:00 PM
The deer fly is a hematophagus (blood-sucking) fly of the genus Chrysops. It is found widely scattered in the tropical regions of West Africa. Most of the species of Chrysops are vectors that transmit the loa loa nematode parasite which causes a type
02/05/2013 19:14:00 PM
Beryllium is a steel-grey, bivalent, hard, light metallic element, the salts of which are sweet. It is used in copper alloys for better fatigue endurance, in springs and in electrical contacts. Its melting point is 1,278º C. Symbol Be; atomic weight
02/04/2013 20:49:00 PM
The Grampus griseus, commonly known as Risso's dolphin, is a cetacean of the dolphin family. It is widely found in northern seas, measuring up to 13 ft (4 m) long. It has a large dorsal fin and a round protruding head.
02/03/2013 18:49:00 PM
A spark gap is the space between to electrodes where sparks occur between them to ignite a combustion engine. At power substation there are big spark gaps, which are used to in high voltage switches.
02/03/2013 09:28:00 AM
Boron is a non-metallic element, occurring naturally only in combination, as in borar, boric acid, etc. It is obtained in amorphous and crystalline form when reduced from its compounds. Symbol B; atomic weight10.812; atomic number 5.
01/31/2013 11:23:00 AM
Hymenoptera is an order of insects comprising the wasps, bees, ants, and sawflies, whose legs and wings are attached to the thorax and are characterized by clearly differentiated head, thorax, and abdomen, and complete metamorphosis. They have two pa
01/28/2013 20:16:00 PM
A stator is the part of an electric motor, generator, or turbine, which remains fixed with respect to a rotating part called rotor. In a motor and generator, it has insulated copper wire coils, which generate a magnetic field. A stator is composed of
01/27/2013 09:45:00 AM
Nickel is a hard silvery-white, ductile and malleable, metallic element, allied to iron and cobalt, not readily oxidized, and with a crystalline structure. It is used chiefly in alloys, in electroplating, and as catalyst in organic synthesis. Its mel
01/23/2013 21:22:00 PM
Lithium is a soft, silver-white, metallic element, which is the lightest of all metals, occurring combined in cerains minerals. With a melting point of 179º C, it is used in ceramics, alloys and optics. Symbol Li; atomic weight 6.94; atomic number 3
01/22/2013 13:11:00 PM
An electromagnet is a device consisting of an iron or steel core which is magnetized by electric current flowing through an enamel-insulated copper coil wound around it. The strength of the magnetic field thus produced will depend on the number loops
01/20/2013 19:47:00 PM
Radon is a chemically inert, radioactive gaseous element, produced by the decay of radium. It is considered a serious health hazard. Symbol Rn; atomic weight 222; atomic number 86.
01/18/2013 20:25:00 PM
Fermium is a synthetic radioactive element, which has ten isotopes, produced by bombardment of plutonium or uranium. Symbol Fm; atomic number 100; valence 2 and 3. It was named after Enrico Fermi, the Italian physicist.
01/16/2013 20:06:00 PM
Dentary is one member of a pair of membrane bones that in lower vertebrates form the distal part of the lower jaws and in mammals comprise the mandible.
01/15/2013 20:08:00 PM
Rhodium is a silvery-white metallic element of the platinum family, forming salts which give rose-colored solutions. It is used in electroplate microscope and instrument parts to prevent corrosion. Its melting point is 1964ºC. Symbol Rh; atomic weig
01/14/2013 17:56:00 PM
Ametropia is an abnormal condition of the eye causing faulty refraction of light rays, as in astigmatism, miopia, etc. In this eye abnormality, images do not fall on the retina.
01/12/2013 19:39:00 PM
The Ampere's law is the law that a magnetic field induced by an electric current is, at any point, directly proportional to the product of the current intensity and the length of the current conductor, inversely proportional to the square of the dist
01/12/2013 19:28:00 PM
Terbium is a rare-earth, metallic element present in certain minerals, such as gadolinite and monazite and yielding colorless salts. It has a melting point of 1356º C. Symbol Tb; atomic weight 158.92; atomic number 65; valence 3, 4.
01/11/2013 19:16:00 PM
Americium is a radioactive metallic element, one of the products of high-energy helium bombardment of uranium and plutonium. It is used in smoke detectors and industrial gauges. Symbol Am; atomic number 95; atomic weight; valence 3, 4, 5, 6.
01/10/2013 17:33:00 PM
Yttrium is a rare, trivalent, silvery, metallic element which is found in gadolinite and other minerals. It oxidizes when heated and reacts with water, but remains stable in air. Yttrium is used as a catalyst and in alloys. Symbol Y; atomic weight 88
01/09/2013 20:14:00 PM
Diphtheria is a febrile, infectious disease caused by a bacterium: Klebs-Löffler bacillus, or Corynebacterium diphtheriae, which produces toxins that destroy the cells of the body. It is marked by fever and the development of a false membrane or pat
01/08/2013 16:54:00 PM
Strontium is a bivalent, silvery metallic element whose compounds resemble those of calcium. It is found in nature only in the combined state, as in strontianite, which is used in fireworks, flares, and tracer bullets. Strontium melting point is 770
01/07/2013 18:39:00 PM
Zircon is a brown common mineral, ziconium silicate Zr2Si04, occurring in small tetragonal crystals or grains of various colors, usually opaque. It is found in ignious and metamorphic rocks in Brazil, Australia, the United States, etc.
01/05/2013 17:22:00 PM
The martial eagle (Polemaetus bellicosus) is a bird of prey, which inhabits the open regions of sub-Saharan Africa. It is a large and heavy eagle, with a wingspan of up to 2.20 m and a weight of 6 kg (12.5 lb). Its head, wings, and back are black and
01/04/2013 19:06:00 PM
The crested eagle is a tropical eagle of the genus Morphnus. It weighs between 4 and 6 pounds and has greyish white head and breast and black back and wings. It is found in Central and South America, from Guatemala to northern Argentina. The crested
01/03/2013 14:22:00 PM
Zirconium is a metallic element found combined in zircon, baddeleyite, etc., resembling titanium chemically. It is used in steel metallurgy, as a refractory, as scavenger, and as opacifier in vitrous enamel. It has a melting point of 1,855ºC. Symbol
01/02/2013 20:31:00 PM
Palladium is a rare metallic element of the platinum group. It is silver-white, ductile, and malleable. Found in nickel and gold ores, it is used chiefly as catalyst and in dentistry, surgical instruments, and other alloys. It has a melting point of
01/01/2013 11:01:00 AM
Rubidium is a silver-white, metallic, active element, which resembles potassium. It ignites in air and reacts with water. It is used in photoelectric cells and electronic vacuum tubes. Rubidium is found world wide in carnallite and pullocite. Symbol
12/29/2012 16:38:00 PM
Cadmium is a white, ductile, divalent, metallic element which resembles tin in appearance. It is used in plating, in making alloys, and in rechargeable batteries. It is found in copper and zinc ores. Symbol Cd; atomic weight 112.41; atomic number 48;
12/28/2012 19:01:00 PM
The transverse cervical artery is a blood vessel which arises from the thyrocervical trunk and travels backward across the base of the neck, giving off two branches; a superficial branch and a deep branch.
12/27/2012 13:36:00 PM
Polonium is a radioactive metallic element, discovered by M and Mme Curie in 1898. It is found in small quantities in uranium ores. The isotope polonium-210 is produced by bombarding bismuth with neutrons. It is used in the control of static electric
12/26/2012 17:37:00 PM
Platinum is a heavy, greyish-white, highly malleable and ductile metallic element. It is resistant to the majority of chemicals, practically unoxidizable, except by the presence of bases. It is fusable only to extremely high temperatures (melting poi
12/23/2012 17:06:00 PM
Barium is a whitish malleable, metallic element. It is divalent, occurring in combination chiefly as barite and witherite. Symbol Ba; atomic weight 137.34; atomic number 56; valence 2. Barium has a boiling point of 1,140º. It is used in alloys with
12/22/2012 17:39:00 PM
Krypton is an inert, monatomic, oderless, gaseous element, present in very small amounts at high altitudes in the atmosphere. It has a melting point of -156.6º C. It is used in high-power tungsten-filament light bulbs. Symbol Kr, atomic weight 83.8,
12/21/2012 19:41:00 PM
Scheelite is a calcium tungstate (mineral containing calcium and tungsten), usually occurring in tetragonal crystal. It is found in limestones intruded by granites. Its symbol is CaWO4.
12/21/2012 17:40:00 PM
Wolframite is a mineral, iron manganese tungstate (Fe, Mn) WO4, which occurs in heavy greyish-black to brownish-black tabular or bladed crystals. Found in quartz veins, it is an important ore of tungsten.
12/19/2012 20:31:00 PM
Tungsten is a rare metallic element having a bright-gray color. It is extremely hard and dense, has a metallic luster and a very high melting point of 3410º C. Found in wolframite, tungstite and other minerals, it is used in alloys of high speed cut
12/18/2012 16:50:00 PM
Radium is a highly radiactive metallic element which produces radon and alpha rays when it disintegrates, with the latter being regarded a positively charged particles of helium. The disintegration of radium is understood to be a process by which an
12/17/2012 18:21:00 PM
Plutonium (Pu) is a radioactive element, capable of self-maintained explosive fission. It was isolated from uranium 238 during research on the atomic bomb in 1940 by neutron bombardment. It has 13 isotopes, from which Pu 239 and Pu 244, with a half-l
12/15/2012 18:47:00 PM
Monazite is a reddish brown mineral, which is a phosphate of cerium and lanthanum, containing about 10% of thorium. Purified from other minerals, it is found in South Africa, North America, Brazil, and Australia.
12/14/2012 19:24:00 PM
Thorium is a greyish white, lustrous, malleable, radioactive, metallic element present in monazite. It is used as a source of nuclear energy, in vacuum tube filament coating, and in alloys. Symbol Th, its atomic number is 90, atomic weigh 232.038, an
12/13/2012 19:16:00 PM
Iridium is a hard metallic element resembling platinum. Dense and corrosion-resistant, it is used in platinum alloys, in bearings, surgical tools, and for the points of gold pens. It has valence 3, 4, an atomic weight 192.2, and an atomic number 77.
12/12/2012 17:08:00 PM
Osmium is a hard heavy metallic element, whose symbol is Os. It has the greatest density of the known chemical elements. It forms octavalent compounds, as OsO4. Osmium is used chiefly as a catalyst, in alloys, and in the manufacture of electric light
12/11/2012 16:47:00 PM
Like all state-organized societies, the United States is a stratified and has a complex system of classes, minorities and other hierarchical groups. Emic (subjective) versions of US stratification hierarchies differ from one class to another and bear
12/09/2012 17:45:00 PM
Also called Bullet Cluster, the Cluster 1E0657 is a group of individual galaxies lying at 3.4 billion light years away. The observation and studies of these colliding galaxies have provided evidence of the dark matter, which is a type of matter that
12/07/2012 18:03:00 PM
Mercury is a planet of the Solar System, lying at 36 million miles (57.9 million Km) away from the Sun; the closest, followed by Venus. It has a rotational period around the Sun of 88 days. The surface of Mercury is rough and full of craters; not onl
12/06/2012 18:48:00 PM
A remora is any of several species of elongated ocean fish which swim attached to bigger fish, such as swordfish, sharks, whales, marlins, etc., event to ships hulls. They feed on their host parasites. Aside from their 3 ft-long, elongated body, remo
12/05/2012 18:03:00 PM
The Southern Cross is a small constellation of bright stars lying in such a manner to form the shape of a cross (Crux in Latin). It is seen only from the Earth's southern hemisphere as one looks southward. Located in the Milky Way, close to Centaurus
12/04/2012 19:55:00 PM
Quantum fluctuation is a transient alteration in the amount of energy in a point in space, which leads to the creation of particle-antiparticle pairs of virtual particles. It is part of the uncertainty principle of German physicist Werner Heisenberg.
12/03/2012 16:27:00 PM
A comet is a celestial object composed of water ice, frozen gases and small particles. It has nucleus or head, which is enveloped by ammonia and carbon dioxide gas that form a long tail-like beam called "coma". Comets orbit around the Sun in an ellip
12/02/2012 20:12:00 PM
Mars is a planet of the Solar System, the nearest to the Earth, occupying the fourth position in distance from the Sun at 229 million km away from it. With a diameter of 4,200 miles (6,800 km), Mars is about half the size of the Earth. It has ice cap