Astronomy Picture of the Day

Astronomy Picture of the Day

Discover the cosmos!Each day a different image or photograph of our fascinating universe isfeatured, along with a brief explanation written by a professional astronomer.

2019 April 11

Explanation: What does a black hole look like?To find out, radio telescopes from around the Earth coordinated observations of black holes with the largest known event horizons on the sky. Alone, black holes are just black, but these monster attractors are known to be surrounded by glowing gas. The first image was released yesterday and resolved the area around the black hole at the center of galaxy M87 on a scale below that expected for its event horizon. Pictured, the dark central region is not the event horizon, but rather the black hole’s shadow — the central region of emitting gas darkened by the central black hole’s gravity.The size and shape of the shadow is determined by bright gas near the event horizon, by strong gravitational lensing deflections, and by the black hole’s spin. In resolving this black hole’s shadow, the Event Horizon Telescope (ETH) bolstered evidence that Einstein’s gravity works even in extreme regions, and gave clear evidence that M87 has a central spinning black hole of about 6 billion solar masses. The EHT is not done — future observations will be geared toward even higher resolution, better tracking of variability, and exploring the immediate vicinity of the black hole in the center of our Milky Way Galaxy.

Authors & editors: Robert Nemiroff(MTU) &Jerry Bonnell (UMCP)NASA Official: Phillip NewmanSpecific rights apply.NASA WebPrivacy Policy and Important NoticesA service of:ASD atNASA /GSFC& Michigan Tech. U.

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Astronomy Picture of the Day

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Since the late 19th century astronomy has expanded to include astrophysics, the application of physical and chemical knowledge to an understanding of the nature of celestial objects and the physical processes that control their formation, evolution, and emission of radiation. In addition, the gases and dust particles around and between the stars have become the subjects of much research. Study of the nuclear reactions that provide the energy radiated by stars has shown how the diversity of atoms found in nature can be derived from a universe that, following the first few minutes of its existence, consisted only of hydrogen, helium, and a trace of lithium. Concerned with phenomena on the largest scale is cosmology, the study of the evolution of the universe. Astrophysics has transformed cosmology from a purely speculative activity to a modern science capable of predictions that can be tested.

Its great advances notwithstanding, astronomy is still subject to a major constraint: it is inherently an observational rather than an experimental science. Almost all measurements must be performed at great distances from the objects of interest, with no control over such quantities as their temperature, pressure, or chemical composition. There are a few exceptions to this limitationnamely, meteorites (most of which are from the asteroid belt, though some are from the Moon or Mars), rock and soil samples brought back from the Moon, samples of comet and asteroid dust returned by robotic spacecraft, and interplanetary dust particles collected in or above the stratosphere. These can be examined with laboratory techniques to provide information that cannot be obtained in any other way. In the future, space missions may return surface materials from Mars, or other objects, but much of astronomy appears otherwise confined to Earth-based observations augmented by observations from orbiting satellites and long-range space probes and supplemented by theory.

The solar system took shape 4.57 billion years ago, when it condensed within a large cloud of gas and dust. Gravitational attraction holds the planets in their elliptical orbits around the Sun. In addition to Earth, five major planets (Mercury, Venus, Mars, Jupiter, and Saturn) have been known from ancient times. Since then only two more have been discovered: Uranus by accident in 1781 and Neptune in 1846 after a deliberate search following a theoretical prediction based on observed irregularities in the orbit of Uranus. Pluto, discovered in 1930 after a search for a planet predicted to lie beyond Neptune, was considered a major planet until 2006, when it was redesignated a dwarf planet by the International Astronomical Union.

The average Earth-Sun distance, which originally defined the astronomical unit (AU), provides a convenient measure for distances within the solar system. The astronomical unit was originally defined by observations of the mean radius of Earths orbit but is now defined as 149,597,870.7 km (about 93 million miles). Mercury, at 0.4 AU, is the closest planet to the Sun, while Neptune, at 30.1 AU, is the farthest. Plutos orbit, with a mean radius of 39.5 AU, is sufficiently eccentric that at times it is closer to the Sun than is Neptune. The planes of the planetary orbits are all within a few degrees of the ecliptic, the plane that contains Earths orbit around the Sun. As viewed from far above Earths North Pole, all planets move in the same (counterclockwise) direction in their orbits.

Most of the mass of the solar system is concentrated in the Sun, with its 1.99 1033 grams. Together, all of the planets amount to 2.7 1030 grams (i.e., about one-thousandth of the Suns mass), and Jupiter alone accounts for 71 percent of this amount. The solar system also contains five known objects of intermediate size classified as dwarf planets and a very large number of much smaller objects collectively called small bodies. The small bodies, roughly in order of decreasing size, are the asteroids, or minor planets; comets, including Kuiper belt, Centaur, and Oort cloud objects; meteoroids; and interplanetary dust particles. Because of their starlike appearance when discovered, the largest of these bodies were termed asteroids, and that name is widely used, but, now that the rocky nature of these bodies is understood, their more descriptive name is minor planets.

The four inner, terrestrial planetsMercury, Venus, Earth, and Marsalong with the Moon have average densities in the range of 3.95.5 grams per cubic cm, setting them apart from the four outer, giant planetsJupiter, Saturn, Uranus, and Neptunewhose densities are all close to 1 gram per cubic cm, the density of water. The compositions of these two groups of planets must therefore be significantly different. This dissimilarity is thought to be attributable to conditions that prevailed during the early development of the solar system (see below Theories of origin). Planetary temperatures now range from around 170 C (330 F, 440 K) on Mercurys surface through the typical 15 C (60 F, 290 K) on Earth to 135 C (210 F, 140 K) on Jupiter near its cloud tops and down to 210 C (350 F, 60 K) near Neptunes cloud tops. These are average temperatures; large variations exist between dayside and nightside for planets closest to the Sun, except for Venus with its thick atmosphere.

The surfaces of the terrestrial planets and many satellites show extensive cratering, produced by high-speed impacts (see meteorite crater). On Earth, with its large quantities of water and an active atmosphere, many of these cosmic footprints have eroded, but remnants of very large craters can be seen in aerial and spacecraft photographs of the terrestrial surface. On Mercury, Mars, and the Moon, the absence of water and any significant atmosphere has left the craters unchanged for billions of years, apart from disturbances produced by infrequent later impacts. Volcanic activity has been an important force in the shaping of the surfaces of the Moon and the terrestrial planets. Seismic activity on the Moon has been monitored by means of seismometers left on its surface by Apollo astronauts and by Lunokhod robotic rovers. Cratering on the largest scale seems to have ceased about three billion years ago, although on the Moon there is clear evidence for a continued cosmic drizzle of small particles, with the larger objects churning (gardening) the lunar surface and the smallest producing microscopic impact pits in crystals in the lunar rocks.

All of the planets apart from the two closest to the Sun (Mercury and Venus) have natural satellites (moons) that are very diverse in appearance, size, and structure, as revealed in close-up observations from long-range space probes. The four outer dwarf planets have moons; Pluto has at least five moons, including one, Charon, fully half the size of Pluto itself. Over 200 asteroids and 80 Kuiper belt objects also have moons. Four planets (Jupiter, Saturn, Uranus, and Neptune), one dwarf planet (Haumea), and one Centaur object (Chariklo) have rings, disklike systems of small rocks and particles that orbit their parent bodies.

During the U.S. Apollo missions a total weight of 381.7 kg (841.5 pounds) of lunar material was collected; an additional 300 grams (0.66 pounds) was brought back by unmanned Soviet Luna vehicles. About 15 percent of the Apollo samples have been distributed for analysis, with the remainder stored at the NASA Johnson Space Center, Houston, Texas. The opportunity to employ a wide range of laboratory techniques on these lunar samples has revolutionized planetary science. The results of the analyses have enabled investigators to determine the composition and age of the lunar surface. Seismic observations have made it possible to probe the lunar interior. In addition, retroreflectors left on the Moons surface by Apollo astronauts have allowed high-power laser beams to be sent from Earth to the Moon and back, permitting scientists to monitor the Earth-Moon distance to an accuracy of a few centimetres. This experiment, which has provided data used in calculations of the dynamics of the Earth-Moon system, has shown that the separation of the two bodies is increasing by 4.4 cm (1.7 inches) each year. (For additional information on lunar studies, see Moon.)

Mercury is too hot to retain an atmosphere, but Venuss brilliant white appearance is the result of its being completely enveloped in thick clouds of carbon dioxide, impenetrable at visible wavelengths. Below the upper clouds, Venus has a hostile atmosphere containing clouds of sulfuric acid droplets. The cloud cover shields the planets surface from direct sunlight, but the energy that does filter through warms the surface, which then radiates at infrared wavelengths. The long-wavelength infrared radiation is trapped by the dense clouds such that an efficient greenhouse effect keeps the surface temperature near 465 C (870 F, 740 K). Radar, which can penetrate the thick Venusian clouds, has been used to map the planets surface. In contrast, the atmosphere of Mars is very thin and is composed mostly of carbon dioxide (95 percent), with very little water vapour; the planets surface pressure is only about 0.006 that of Earth. The outer planets have atmospheres composed largely of light gases, mainly hydrogen and helium.

Each planet rotates on its axis, and nearly all of them rotate in the same directioncounterclockwise as viewed from above the ecliptic. The two exceptions are Venus, which rotates in the clockwise direction beneath its cloud cover, and Uranus, which has its rotation axis very nearly in the plane of the ecliptic.

Some of the planets have magnetic fields. Earths field extends outward until it is disturbed by the solar windan outward flow of protons and electrons from the Sunwhich carries a magnetic field along with it. Through processes not yet fully understood, particles from the solar wind and galactic cosmic rays (high-speed particles from outside the solar system) populate two doughnut-shaped regions called the Van Allen radiation belts. The inner belt extends from about 1,000 to 5,000 km (600 to 3,000 miles) above Earths surface, and the outer from roughly 15,000 to 25,000 km (9,300 to 15,500 miles). In these belts, trapped particles spiral along paths that take them around Earth while bouncing back and forth between the Northern and Southern hemispheres, with their orbits controlled by Earths magnetic field. During periods of increased solar activity, these regions of trapped particles are disturbed, and some of the particles move down into Earths atmosphere, where they collide with atoms and molecules to produce auroras.

Jupiter has a magnetic field far stronger than Earths and many more trapped electrons, whose synchrotron radiation (electromagnetic radiation emitted by high-speed charged particles that are forced to move in curved paths, as under the influence of a magnetic field) is detectable from Earth. Bursts of increased radio emission are correlated with the position of Io, the innermost of the four Galilean moons of Jupiter. Saturn has a magnetic field that is much weaker than Jupiters, but it too has a region of trapped particles. Mercury has a weak magnetic field that is only about 1 percent as strong as Earths and shows no evidence of trapped particles. Uranus and Neptune have fields that are less than one-tenth the strength of Saturns and appear much more complex than that of Earth. No field has been detected around Venus or Mars.

More than 500,000 asteroids with well-established orbits are known, and thousands of additional objects are discovered each year. Hundreds of thousands more have been seen, but their orbits have not been as well determined. It is estimated that several million asteroids exist, but most are small, and their combined mass is estimated to be less than a thousandth that of Earth. Most of the asteroids have orbits close to the ecliptic and move in the asteroid belt, between 2.3 and 3.3 AU from the Sun. Because some asteroids travel in orbits that can bring them close to Earth, there is a possibility of a collision that could have devastating results (see Earth impact hazard).

Comets are considered to come from a vast reservoir, the Oort cloud, orbiting the Sun at distances of 20,00050,000 AU or more and containing trillions of icy objectslatent comet nucleiwith the potential to become active comets. Many comets have been observed over the centuries. Most make only a single pass through the inner solar system, but some are deflected by Jupiter or Saturn into orbits that allow them to return at predictable times. Halleys Comet is the best known of these periodic comets; its next return into the inner solar system is predicted for 2061. Many short-period comets are thought to come from the Kuiper belt, a region lying mainly between 30 AU and 50 AU from the Sunbeyond Neptunes orbit but including part of Plutosand housing perhaps hundreds of millions of comet nuclei. Very few comet masses have been well determined, but most are probably less than 1018 grams, one-billionth the mass of Earth.

Since the 1990s more than a thousand comet nuclei in the Kuiper belt have been observed with large telescopes; a few are about half the size of Pluto, and Pluto is the largest Kuiper belt object. Plutos orbital and physical characteristics had long caused it to be regarded as an anomaly among the planets. However, after the discovery of numerous other Pluto-like objects beyond Neptune, Pluto was seen to be no longer unique in its neighbourhood but rather a giant member of the local population. Consequently, in 2006 astronomers at the general assembly of the International Astronomical Union elected to create the new category of dwarf planets for objects with such qualifications. Pluto, Eris, and Ceres, the latter being the largest member of the asteroid belt, were given this distinction. Two other Kuiper belt objects, Makemake and Haumea, were also designated as dwarf planets.

Smaller than the observed asteroids and comets are the meteoroids, lumps of stony or metallic material believed to be mostly fragments of asteroids. Meteoroids vary from small rocks to boulders weighing a ton or more. A relative few have orbits that bring them into Earths atmosphere and down to the surface as meteorites. Most meteorites that have been collected on Earth are probably from asteroids. A few have been identified as being from the Moon, Mars, or the asteroid Vesta.

Meteorites are classified into three broad groups: stony (chondrites and achondrites; about 94 percent), iron (5 percent), and stony-iron (1 percent). Most meteoroids that enter the atmosphere heat up sufficiently to glow and appear as meteors, and the great majority of these vaporize completely or break up before they reach the surface. Many, perhaps most, meteors occur in showers (see meteor shower) and follow orbits that seem to be identical with those of certain comets, thus pointing to a cometary origin. For example, each May, when Earth crosses the orbit of Halleys Comet, the Eta Aquarid meteor shower occurs. Micrometeorites (interplanetary dust particles), the smallest meteoroidal particles, can be detected from Earth-orbiting satellites or collected by specially equipped aircraft flying in the stratosphere and returned for laboratory inspection. Since the late 1960s numerous meteorites have been found in the Antarctic on the surface of stranded ice flows (see Antarctic meteorites). Some meteorites contain microscopic crystals whose isotopic proportions are unique and appear to be dust grains that formed in the atmospheres of different stars.

The age of the solar system, taken to be close to 4.6 billion years, has been derived from measurements of radioactivity in meteorites, lunar samples, and Earths crust. Abundances of isotopes of uranium, thorium, and rubidium and their decay products, lead and strontium, are the measured quantities.

Assessment of the chemical composition of the solar system is based on data from Earth, the Moon, and meteorites as well as on the spectral analysis of light from the Sun and planets. In broad outline, the solar system abundances of the chemical elements decrease with increasing atomic weight. Hydrogen atoms are by far the most abundant, constituting 91 percent; helium is next, with 8.9 percent; and all other types of atoms together amount to only 0.1 percent.

The origin of Earth, the Moon, and the solar system as a whole is a problem that has not yet been settled in detail. The Sun probably formed by condensation of the central region of a large cloud of gas and dust, with the planets and other bodies of the solar system forming soon after, their composition strongly influenced by the temperature and pressure gradients in the evolving solar nebula. Less-volatile materials could condense into solids relatively close to the Sun to form the terrestrial planets. The abundant, volatile lighter elements could condense only at much greater distances to form the giant gas planets.

In the1990s astronomers confirmed that other stars have one or more planets revolving around them. Studies of these planetary systems have both supported and challenged astronomers theoretical models of how Earths solar system formed. Unlike the solar system, many extrasolar planetary systems have large gas giants like Jupiter orbiting very close to their stars, and in some cases these hot Jupiters are closer to their star than Mercury is to the Sun.

That so many gas giants, which form in the outer regions of their system, end up so close to their stars suggests that gas giants migrate and that such migration may have happened in the solar systems history. According to the Grand Tack hypothesis, Jupiter may have done so within a few million years of the solar systems formation. In this scenario, Jupiter is the first giant planet to form, at about 3 AU from the Sun. Drag from the protoplanetary disk causes it to fall inward to about 1.5 AU. However, by this time, Saturn begins to form at about 3 AU and captures Jupiter in a 3:2 resonance. (That is, for every three revolutions Jupiter makes, Saturn makes two.) The two planets migrate outward and clear away any material that would have gone to making Mars bigger. Mars should be bigger than Venus or Earth, but it is only half their size. The Grand Tack, in which Jupiter moves inward and then outward, explains Marss small size.

About 500 million years after the Grand Tack, according to the Nice Model (named after the French city where it was first proposed), after the four giant planetsJupiter, Saturn, Uranus, and Neptuneformed, they orbited 517 AU from the Sun. These planets were in a disk of smaller bodies called planetesimals and in orbital resonances with each other. About four billion years ago, gravitational interactions with the planetesimals increased the eccentricity of the planets orbits, driving them out of resonance. Saturn, Uranus and Neptune migrated outward, and Jupiter migrated slightly inward. (Uranus and Neptune may even have switched places.) This migration scattered the disk, causing the Late Heavy Bombardment. The final remnant of the disk became the Kuiper belt.

The origin of the planetary satellites is not entirely settled. As to the origin of the Moon, the opinion of astronomers long oscillated between theories that saw its origin and condensation as simultaneous with the formation of Earth and those that posited a separate origin for the Moon and its later capture by Earths gravitational field. Similarities and differences in abundances of the chemical elements and their isotopes on Earth and the Moon challenged each group of theories. Finally, in the 1980s a model emerged that gained the support of most lunar scientiststhat of a large impact on Earth and the expulsion of material that subsequently formed the Moon. (See Moon: Origin and evolution.) For the outer planets, with their multiple satellites, many very small and quite unlike one another, the picture is less clear. Some of these moons have relatively smooth icy surfaces, whereas others are heavily cratered; at least one, Jupiters Io, is volcanic. Some of the moons may have formed along with their parent planets, and others may have formed elsewhere and been captured.

The measurable quantities in stellar astrophysics include the externally observable features of the stars: distance, temperature, radiation spectrum and luminosity, composition (of the outer layers), diameter, mass, and variability in any of these. Theoretical astrophysicists use these observations to model the structure of stars and to devise theories for their formation and evolution. Positional information can be used for dynamical analysis, which yields estimates of stellar masses.

In a system dating back at least to the Greek astronomer-mathematician Hipparchus in the 2nd century bce, apparent stellar brightness (m) is measured in magnitudes. Magnitudes are now defined such that a first-magnitude star is 100 times brighter than a star of sixth magnitude. The human eye cannot see stars fainter than about sixth magnitude, but modern instruments used with large telescopes can record stars as faint as about 30th magnitude. By convention, the absolute magnitude (M) is defined as the magnitude that a star would appear to have if it were located at a standard distance of 10 parsecs. These quantities are related through the expression m M = 5 log10 r 5, in which r is the stars distance in parsecs.

The magnitude scale is anchored on a group of standard stars. An absolute measure of radiant power is luminosity, which is related to the absolute magnitude and usually expressed in ergs per second (ergs/sec). (Sometimes the luminosity is stated in terms of the solar luminosity, 3.86 1033 ergs/sec.) Luminosity can be calculated when m and r are known. Correction might be necessary for the interstellar absorption of starlight.

There are several methods for measuring a stars diameter. From the brightness and distance, the luminosity (L) can be calculated, and, from observations of the brightness at different wavelengths, the temperature (T) can be calculated. Because the radiation from many stars can be well approximated by a Planck blackbody spectrum (see Plancks radiation law), these measured quantities can be related through the expression L = 4R2T4, thus providing a means of calculating R, the stars radius. In this expression, is the Stefan-Boltzmann constant, 5.67 105 ergs/cm2K4sec, in which K is the temperature in kelvins. (The radius R refers to the stars photosphere, the region where the star becomes effectively opaque to outside observation.) Stellar angular diameters can be measured through interferometrythat is, the combining of several telescopes together to form a larger instrument that can resolve sizes smaller than those that an individual telescope can resolve. Alternatively, the intensity of the starlight can be monitored during occultation by the Moon, which produces diffraction fringes whose pattern depends on the angular diameter of the star. Stellar angular diameters of several milliarcseconds can be measured.

Many stars occur in binary systems (see binary star), in which the two partners orbit their mutual centre of mass. Such a system provides the best measurement of stellar masses. The period (P) of a binary system is related to the masses of the two stars (m1 and m2) and the orbital semimajor axis (mean radius; a) via Keplers third law: P2 = 42a3/G(m1 + m2). (G is the universal gravitational constant.) From diameters and masses, average values of the stellar density can be calculated and thence the central pressure. With the assumption of an equation of state, the central temperature can then be calculated. For example, in the Sun the central density is 158 grams per cubic cm; the pressure is calculated to be more than one billion times the pressure of Earths atmosphere at sea level and the temperature around 15 million K (27 million F). At this temperature, all atoms are ionized, and so the solar interior consists of a plasma, an ionized gas with hydrogen nuclei (i.e., protons), helium nuclei, and electrons as major constituents. A small fraction of the hydrogen nuclei possess sufficiently high speeds that, on colliding, their electrostatic repulsion is overcome, resulting in the formation, by means of a set of fusion reactions, of helium nuclei and a release of energy (see proton-proton cycle). Some of this energy is carried away by neutrinos, but most of it is carried by photons to the surface of the Sun to maintain its luminosity.

Other stars, both more and less massive than the Sun, have broadly similar structures, but the size, central pressure and temperature, and fusion rate are functions of the stars mass and composition. The stars and their internal fusion (and resulting luminosity) are held stable against collapse through a delicate balance between the inward pressure produced by gravitational attraction and the outward pressure supplied by the photons produced in the fusion reactions.

Stars that are in this condition of hydrostatic equilibrium are termed main-sequence stars, and they occupy a well-defined band on the Hertzsprung-Russell (H-R) diagram, in which luminosity is plotted against colour index or temperature. Spectral classification, based initially on the colour index, includes the major spectral types O, B, A, F, G, K and M, each subdivided into 10 parts (see star: Stellar spectra). Temperature is deduced from broadband spectral measurements in several standard wavelength intervals. Measurement of apparent magnitudes in two spectral regions, the B and V bands (centred on 4350 and 5550 angstroms, respectively), permits calculation of the colour index, CI = mB mV, from which the temperature can be calculated.

For a given temperature, there are stars that are much more luminous than main-sequence stars. Given the dependence of luminosity on the square of the radius and the fourth power of the temperature (R2T4 of the luminosity expression above), greater luminosity implies larger radius, and such stars are termed giant stars or supergiant stars. Conversely, stars with luminosities much less than those of main-sequence stars of the same temperature must be smaller and are termed white dwarf stars. Surface temperatures of white dwarfs typically range from 10,000 to 12,000 K (18,000 to 21,000 F), and they appear visually as white or blue-white.

The strength of spectral lines of the more abundant elements in a stars atmosphere allows additional subdivisions within a class. Thus, the Sun, a main-sequence star, is classified as G2 V, in which the V denotes main sequence. Betelgeuse, a red giant with a surface temperature about half that of the Sun but with a luminosity of about 10,000 solar units, is classified as M2 Iab. In this classification, the spectral type is M2, and the Iab indicates a giant, well above the main sequence on the H-R diagram.

The range of physically allowable masses for stars is very narrow. If the stars mass is too small, the central temperature will be too low to sustain fusion reactions. The theoretical minimum stellar mass is about 0.08 solar mass. An upper theoretical bound called the Eddington limit, of several hundred solar masses, has been suggested, but this value is not firmly defined. Stars as massive as this will have luminosities about one million times greater than that of the Sun.

A general model of star formation and evolution has been developed, and the major features seem to be established. A large cloud of gas and dust can contract under its own gravitational attraction if its temperature is sufficiently low. As gravitational energy is released, the contracting central material heats up until a point is reached at which the outward radiation pressure balances the inward gravitational pressure, and contraction ceases. Fusion reactions take over as the stars primary source of energy, and the star is then on the main sequence. The time to pass through these formative stages and onto the main sequence is less than 100 million years for a star with as much mass as the Sun. It takes longer for less massive stars and a much shorter time for those much more massive.

Once a star has reached its main-sequence stage, it evolves relatively slowly, fusing hydrogen nuclei in its core to form helium nuclei. Continued fusion not only releases the energy that is radiated but also results in nucleosynthesis, the production of heavier nuclei.

Stellar evolution has of necessity been followed through computer modeling, because the timescales for most stages are generally too extended for measurable changes to be observed, even over a period of many years. One exception is the supernova, the violently explosive finale of certain stars. Different types of supernovas can be distinguished by their spectral lines and by changes in luminosity during and after the outburst. In Type Ia, a white dwarf star attracts matter from a nearby companion; when the white dwarfs mass exceeds about 1.4 solar masses, the star implodes and is completely destroyed. Type II supernovas are not as luminous as Type Ia and are the final evolutionary stage of stars more massive than about eight solar masses. Type Ib and Ic supernovas are like Type II in that they are from the collapse of a massive star, but they do not retain their hydrogen envelope.

The nature of the final products of stellar evolution depends on stellar mass. Some stars pass through an unstable stage in which their dimensions, temperature, and luminosity change cyclically over periods of hours or days. These so-called Cepheid variables serve as standard candles for distance measurements (see above Determining astronomical distances). Some stars blow off their outer layers to produce planetary nebulas. The expanding material can be seen glowing in a thin shell as it disperses into the interstellar medium while the remnant core, initially with a surface temperature as high as 100,000 K (180,000 F), cools to become a white dwarf. The maximum stellar mass that can exist as a white dwarf is about 1.4 solar masses and is known as the Chandrasekhar limit. More-massive stars may end up as either neutron stars or black holes.

The average density of a white dwarf is calculated to exceed one million grams per cubic cm. Further compression is limited by a quantum condition called degeneracy (see degenerate gas), in which only certain energies are allowed for the electrons in the stars interior. Under sufficiently great pressure, the electrons are forced to combine with protons to form neutrons. The resulting neutron star will have a density in the range of 10141015 grams per cubic cm, comparable to the density within atomic nuclei. The behaviour of large masses having nuclear densities is not yet sufficiently understood to be able to set a limit on the maximum size of a neutron star, but it is thought to be less than three solar masses.

Still more-massive remnants of stellar evolution would have smaller dimensions and would be even denser that neutron stars. Such remnants are conceived to be black holes, objects so compact that no radiation can escape from within a characteristic distance called the Schwarzschild radius. This critical dimension is defined by Rs = 2GM/c2. (Rs is the Schwarzschild radius, G is the gravitational constant, M is the objects mass, and c is the speed of light.) For an object of three solar masses, the Schwarzschild radius would be about three kilometres. Radiation emitted from beyond the Schwarzschild radius can still escape and be detected.

Although no light can be detected coming from within a black hole, the presence of a black hole may be manifested through the effects of its gravitational field, as, for example, in a binary star system. If a black hole is paired with a normal visible star, it may pull matter from its companion toward itself. This matter is accelerated as it approaches the black hole and becomes so intensely heated that it radiates large amounts of X-rays from the periphery of the black hole before reaching the Schwarzschild radius. Some candidates for stellar black holes have been founde.g., the X-ray source Cygnus X-1. Each of them has an estimated mass clearly exceeding that allowable for a neutron star, a factor crucial in the identification of possible black holes. Supermassive black holes that do not originate as individual stars exist at the centre of active galaxies (see below Study of other galaxies and related phenomena). One such black hole, that at the center of the galaxy M87, has a mass 6.5 billion times that of the Sun and has been directly observed.

Whereas the existence of stellar black holes has been strongly indicated, the existence of neutron stars was confirmed in 1968 when they were identified with the then newly discovered pulsars, objects characterized by the emission of radiation at short and extremely regular intervals, generally between 1 and 1,000 pulses per second and stable to better than a part per billion. Pulsars are considered to be rotating neutron stars, remnants of some supernovas.

Stars are not distributed randomly throughout space. Many stars are in systems consisting of two or three members separated by less than 1,000 AU. On a larger scale, star clusters may contain many thousands of stars. Galaxies are much larger systems of stars and usually include clouds of gas and dust.

The solar system is located within the Milky Way Galaxy, close to its equatorial plane and about 8 kiloparsecs from the galactic centre. The galactic diameter is about 30 kiloparsecs, as indicated by luminous matter. There is evidence, however, for nonluminous matterso-called dark matterextending out nearly twice this distance. The entire system is rotating such that, at the position of the Sun, the orbital speed is about 220 km per second (almost 500,000 miles per hour) and a complete circuit takes roughly 240 million years. Application of Keplers third law leads to an estimate for the galactic mass of about 100 billion solar masses. The rotational velocity can be measured from the Doppler shifts observed in the 21-cm emission line of neutral hydrogen and the lines of millimetre wavelengths from various molecules, especially carbon monoxide. At great distances from the galactic centre, the rotational velocity does not drop off as expected but rather increases slightly. This behaviour appears to require a much larger galactic mass than can be accounted for by the known (luminous) matter. Additional evidence for the presence of dark matter comes from a variety of other observations. The nature and extent of the dark matter (or missing mass) constitutes one of todays major astronomical puzzles.

There are about 100 billion stars in the Milky Way Galaxy. Star concentrations within the galaxy fall into three types: open clusters, globular clusters, and associations (see star cluster). Open clusters lie primarily in the disk of the galaxy; most contain between 50 and 1,000 stars within a region no more than 10 parsecs in diameter. Stellar associations tend to have somewhat fewer stars; moreover, the constituent stars are not as closely grouped as those in the clusters and are for the most part hotter. Globular clusters, which are widely scattered around the galaxy, may extend up to about 100 parsecs in diameter and may have as many as a million stars. The importance to astronomers of globular clusters lies in their use as indicators of the age of the galaxy. Because massive stars evolve more rapidly than do smaller stars, the age of a cluster can be estimated from its H-R diagram. In a young cluster the main sequence will be well populated, but in an old cluster the heavier stars will have evolved away from the main sequence. The extent of the depopulation of the main sequence provides an index of age. In this way, the oldest globular clusters have been found to be about 12.5 billion years old, which should therefore be the minimum age for the galaxy.

The interstellar medium, composed primarily of gas and dust, occupies the regions between the stars. On average, it contains less than one atom in each cubic centimetre, with about 1 percent of its mass in the form of minute dust grains. The gas, mostly hydrogen, has been mapped by means of its 21-cm emission line. The gas also contains numerous molecules. Some of these have been detected by the visible-wavelength absorption lines that they impose on the spectra of more-distant stars, while others have been identified by their own emission lines at millimetre wavelengths. Many of the interstellar molecules are found in giant molecular clouds, wherein complex organic molecules have been discovered.

In the vicinity of a very hot O- or B-type star, the intensity of ultraviolet radiation is sufficiently high to ionize the surrounding hydrogen out to a distance as great as 100 parsecs to produce an H II region, known as a Strmgren sphere. Such regions are strong and characteristic emitters of radiation at radio wavelengths, and their dimensions are well calibrated in terms of the luminosity of the central star. Using radio interferometers, astronomers are able to measure the angular diameters of H II regions even in some external galaxies and can thereby deduce the great distances to those remote systems. This method can be used for distances up to about 30 megaparsecs. (For additional information on H II regions, see nebula: Diffuse nebulae (H II regions).)

Interstellar dust grains scatter and absorb starlight, the effect being roughly inversely proportional to wavelength from the infrared to the near ultraviolet. As a result, stellar spectra tend to be reddened. Absorption typically amounts to about one magnitude per kiloparsec but varies considerably in different directions. Some dusty regions contain silicate materials, identified by a broad absorption feature around a wavelength of 10 m. Other prominent spectral features in the infrared range have been sometimes, but not conclusively, attributed to graphite grains and polycyclic aromatic hydrocarbons (PAHs).

Starlight often shows a small degree of polarization (a few percent), with the effect increasing with stellar distance. This is attributed to the scattering of the starlight from dust grains that have been partially aligned in a weak interstellar magnetic field. The strength of this field is estimated to be a few microgauss, very close to the strength inferred from observations of nonthermal cosmic radio noise. This radio background has been identified as synchrotron radiation, emitted by cosmic-ray electrons traveling at nearly the speed of light and moving along curved paths in the interstellar magnetic field. The spectrum of the cosmic radio noise is close to what is calculated on the basis of measurements of the cosmic rays near Earth.

Cosmic rays constitute another component of the interstellar medium. Cosmic rays that are detected in the vicinity of Earth comprise high-speed nuclei and electrons. Individual particle energies, expressed in electron volts (eV; 1 eV = 1.6 1012 erg), range with decreasing numbers from about 106 eV to more than 1020 eV. Among the nuclei, hydrogen nuclei are the most plentiful at 86 percent, helium nuclei next at 13 percent, and all other nuclei together at about 1 percent. Electrons are about 2 percent as abundant as the nuclear component. (The relative numbers of different nuclei vary somewhat with kinetic energy, while the electron proportion is strongly energy-dependent.)

A minority of cosmic rays detected in Earths vicinity are produced in the Sun, especially at times of increased solar activity (as indicated by sunspots and solar flares). The origin of galactic cosmic rays has not yet been conclusively identified, but they are thought to be produced in stellar processes such as supernova explosions, perhaps with additional acceleration occurring in the interstellar regions. (For additional information on interstellar matter, see Milky Way Galaxy: The general interstellar medium.)

The central region of the Milky Way Galaxy is so heavily obscured by dust that direct observation has become possible only with the development of astronomy at nonvisual wavelengthsnamely, radio, infrared, and, more recently, X-ray and gamma-ray wavelengths. Together, these observations have revealed a nuclear region of intense activity, with a large number of separate sources of emission and a great deal of dust. Detection of gamma-ray emission at a line energy of 511,000 eV, which corresponds to the annihilation of electrons and positrons (the antimatter counterpart of electrons), along with radio mapping of a region no more than 20 AU across, points to a very compact and energetic source, designated Sagittarius A*, at the centre of the galaxy. Sagittarius A* is a supermassive black hole with a mass equivalent to 4,310,000 Suns.

Galaxies are normally classified into three principal types according to their appearance: spiral, elliptical, and irregular. Galactic diameters are typically in the tens of kiloparsecs and the distances between galaxies typically in megaparsecs.

Spiral galaxiesof which the Milky Way system is a characteristic exampletend to be flattened, roughly circular systems with their constituent stars strongly concentrated along spiral arms. These arms are thought to be produced by traveling density waves, which compress and expand the galactic material. Between the spiral arms exists a diffuse interstellar medium of gas and dust, mostly at very low temperatures (below 100 K [280 F, 170 C]). Spiral galaxies are typically a few kiloparsecs in thickness; they have a central bulge and taper gradually toward the outer edges.

Ellipticals show none of the spiral features but are more densely packed stellar systems. They range in shape from nearly spherical to very flattened and contain little interstellar matter. Irregular galaxies number only a few percent of all stellar systems and exhibit none of the regular features associated with spirals or ellipticals.

Properties vary considerably among the different types of galaxies. Spirals typically have masses in the range of a billion to a trillion solar masses, with ellipticals having values from 10 times smaller to 10 times larger and the irregulars generally 10100 times smaller. Visual galactic luminosities show similar spreads among the three types, but the irregulars tend to be less luminous. In contrast, at radio wavelengths the maximum luminosity for spirals is usually 100,000 times less than for ellipticals or irregulars.

Quasars are objects whose spectra display very large redshifts, thus implying (in accordance with the Hubble law) that they lie at the greatest distances (see above Determining astronomical distances). They were discovered in 1963 but remained enigmatic for many years. They appear as starlike (i.e., very compact) sources of radio waveshence their initial designation as quasi-stellar radio sources, a term later shortened to quasars. They are now considered to be the exceedingly luminous cores of distant galaxies. These energetic cores, which emit copious quantities of X-rays and gamma rays, are termed active galactic nuclei (AGN) and include the object Cygnus A and the nuclei of a class of galaxies called Seyfert galaxies. They are powered by the infall of matter into supermassive black holes.

The Milky Way Galaxy is one of the Local Group of galaxies, which contains about four dozen members and extends over a volume about two megaparsecs in diameter. Two of the closest members are the Magellanic Clouds, irregular galaxies about 50 kiloparsecs away. At about 740 kiloparsecs, the Andromeda Galaxy is one of the most distant in the Local Group. Some members of the group are moving toward the Milky Way system while others are traveling away from it. At greater distances, all galaxies are moving away from the Milky Way Galaxy. Their speeds (as determined from the redshifted wavelengths in their spectra) are generally proportional to their distances. The Hubble law relates these two quantities (see above Determining astronomical distances). In the absence of any other method, the Hubble law continues to be used for distance determinations to the farthest objectsthat is, galaxies and quasars for which redshifts can be measured.

Cosmology is the scientific study of the universe as a unified whole, from its earliest moments through its evolution to its ultimate fate. The currently accepted cosmological model is the big bang. In this picture, the expansion of the universe started in an intense explosion 13.8 billion years ago. In this primordial fireball, the temperature exceeded one trillion K, and most of the energy was in the form of radiation. As the expansion proceeded (accompanied by cooling), the role of the radiation diminished, and other physical processes dominated in turn. Thus, after about three minutes, the temperature had dropped to the one-billion-K range, making it possible for nuclear reactions of protons to take place and produce nuclei of deuterium and helium. (At the higher temperatures that prevailed earlier, these nuclei would have been promptly disrupted by high-energy photons.) With further expansion, the time between nuclear collisions had increased and the proportion of deuterium and helium nuclei had stabilized. After a few hundred thousand years, the temperature must have dropped sufficiently for electrons to remain attached to nuclei to constitute atoms. Galaxies are thought to have begun forming after a few million years, but this stage is very poorly understood. Star formation probably started much later, after at least a billion years, and the process continues today.

Observational support for this general model comes from several independent directions. The expansion has been documented by the redshifts observed in the spectra of galaxies. Furthermore, the radiation left over from the original fireball would have cooled with the expansion. Confirmation of this relic energy came in 1965 with one of the most striking cosmic discoveries of the 20th centurythe observation, at short radio wavelengths, of a widespread cosmic radiation corresponding to a temperature of almost 3 K (about 270 C [454 F]). The shape of the observed spectrum is an excellent fit with the theoretical Planck blackbody spectrum. (The present best value for this temperature is 2.735 K, but it is still called three-degree radiation or the cosmic microwave background.) The spectrum of this cosmic radio noise peaks at approximately a one-millimetre wavelength, which is in the far infrared, a difficult region to observe from Earth; however, the spectrum has been well mapped by the Cosmic Background Explorer (COBE), Wilkinson Microwave Anisotropy Probe, and Planck satellites. Additional support for the big bang theory comes from the observed cosmic abundances of deuterium and helium. Normal stellar nucleosynthesis cannot produce their measured quantities, which fit well with calculations of production during the early stages of the big bang.

Early surveys of the cosmic background radiation indicated that it is extremely uniform in all directions (isotropic). Calculations have shown that it is difficult to achieve this degree of isotropy unless there was a very early and rapid inflationary period before the expansion settled into its present mode. Nevertheless, the isotropy posed problems for models of galaxy formation. Galaxies originate from turbulent conditions that produce local fluctuations of density, toward which more matter would then be gravitationally attracted. Such density variations were difficult to reconcile with the isotropy required by observations of the 3 K radiation. This problem was solved when the COBE satellite was able to detect the minute fluctuations in the cosmic background from which the galaxies formed.

The very earliest stages of the big bang are less well understood. The conditions of temperature and pressure that prevailed prior to the first microsecond require the introduction of theoretical ideas of subatomic particle physics. Subatomic particles are usually studied in laboratories with giant accelerators, but the region of particle energies of potential significance to the question at hand lies beyond the range of accelerators currently available. Fortunately, some important conclusions can be drawn from the observed cosmic helium abundance, which is dependent on conditions in the early big bang. The observed helium abundance sets a limit on the number of families of certain types of subatomic particles that can exist.

The age of the universe can be calculated in several ways. Assuming the validity of the big bang model, one attempts to answer the question: How long has the universe been expanding in order to have reached its present size? The numbers relevant to calculating an answer are Hubbles constant (i.e., the current expansion rate), the density of matter in the universe, and the cosmological constant, which allows for change in the expansion rate. In 2003 a calculation based on a fresh determination of Hubbles constant yielded an age of 13.7 billion 200 million years, although the precise value depends on certain assumed details of the model used. Independent estimates of stellar ages have yielded values less than this, as would be expected, but other estimates, based on supernova distance measurements, have arrived at values of about 15 billion years, still consistent, within the errors. In the big bang model the age is proportional to the reciprocal of Hubbles constant, hence the importance of determining H as reliably as possible. For example, a value for H of 100 km/sec/Mpc would lead to an age less than that of many stars, a physically unacceptable result.

A small minority of astronomers have developed alternative cosmological theories that are seriously pursued. The overwhelming professional opinion, however, continues to support the big bang model.

Finally, there is the question of the future behaviour of the universe: Is it open? That is to say, will the expansion continue indefinitely? Or is it closed, such that the expansion will slow down and eventually reverse, resulting in contraction? (The final collapse of such a contracting universe is sometimes termed the big crunch.) The density of the universe seems to be at the critical density; that is, the universe is neither open nor closed but flat. So-called dark energy, a kind of repulsive force that is now believed to be a major component of the universe, appears to be the decisive factor in predictions of the long-term fate of the cosmos. If this energy is a cosmological constant (as proposed in 1917 by Albert Einstein to correct certain problems in his model of the universe), then the result would be a big chill. In this scenario, the universe would continue to expand, but its density would decrease. While old stars would burn out, new stars would no longer form. The universe would become cold and dark. The dark (nonluminous) matter component of the universe, whose composition remains unknown, is not considered sufficient to close the universe and cause it to collapse; it now appears to contribute only a fourth of the density needed for closure.

An additional factor in deciding the fate of the universe might be the mass of neutrinos. For decades the neutrino had been postulated to have zero mass, although there was no compelling theoretical reason for this to be so. From the observation of neutrinos generated in the Sun and other celestial sources such as supernovas, in cosmic-ray interactions with Earths atmosphere, and in particle accelerators, investigators have concluded that neutrinos have some mass, though only an extremely small fraction of the mass of an electron. Although there are vast numbers of neutrinos in the universe, the sum of such small neutrino masses appears insufficient to close the universe.

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Astronomy | Definition of Astronomy by Merriam-Webster

The Difference Between Astronomy and Astrology

Some may find it easy to confuse astronomy and astrology. At one time, these two words actually were synonymous (that is, astronomy once meant what astrology means today), but they have since moved apart from each other. In current use, astronomy is concerned with the study of objects and matter outside the earth’s atmosphere, while astrology is the purported divination of how stars and planets influence our lives. Put bluntly, astronomy is a science, and astrology is not.

Middle English astronomie, from Anglo-French, from Latin astronomia, from Greek, from astr- + -nomia -nomy

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Medicine | Define Medicine at Dictionary.com

n.

c.1200, “medical treatment, cure, remedy,” also used figuratively, of spiritual remedies, from Old French medecine (Modern French mdicine) “medicine, art of healing, cure, treatment, potion,” from Latin medicina “the healing art, medicine; a remedy,” also used figuratively, perhaps originally ars medicina “the medical art,” from fem. of medicinus (adj.) “of a doctor,” from medicus “a physician” (see medical); though OED finds evidence for this is wanting. Meaning “a medicinal potion or plaster” in English is mid-14c.

To take (one’s) medicine “submit to something disagreeable” is first recorded 1865. North American Indian medicine-man “shaman” is first attested 1801, from American Indian adoption of the word medicine in sense of “magical influence.” The U.S.-Canadian boundary they called Medicine Line (first attested 1910), because it conferred a kind of magic protection: punishment for crimes committed on one side of it could be avoided by crossing over to the other. Medicine show “traveling show meant to attract a crowd so patent medicine can be sold to them” is American English, 1938. Medicine ball “stuffed leather ball used for exercise” is from 1889.

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Medicine | Define Medicine at Dictionary.com

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Men often have a hard time acknowledging erectile dysfunction, or ED. But it can leave their partner feeling confused or even blaming themselves for something not within their control.First, know that while the odds of ED rise after age 50, many men experience normal physical changes that are not ED. Erections may not be as firm as they once were,…

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WebMD My Medicine Help

Q: What is an interaction?

A: Mixing certain medicines together may cause a bad reaction. This is called an interaction. For example, one medicine may cause side effects that create problems with other medicines. Or one medicine may make another medicine stronger or weaker.

Q: How do you classify the seriousness of an interaction?

A: The following classification is used:

Contraindicated: Never use this combination of drugs because of high risk for dangerous interaction

Serious: Potential for serious interaction; regular monitoring by your doctor required or alternate medication may be needed

Significant: Potential for significant interaction (monitoring by your doctor is likely required)

Mild: Interaction is unlikely, minor, or nonsignificant

Q: What should I do if my medications show interactions?

A: Call your doctor or pharmacist if you are concerned about an interaction. Do not stop taking any prescribed medication without your doctor’s approval. Sometimes the risk of not taking the medication outweighs the risk or the interaction.

Q: Why can’t I enter my medication?

A: There may be medications, especially otc or supplements, that have not been adequately studied for interactions. If we do not have interaction information for a certain medication it can’t be saved in My Medicine.

Q: Do you cover all FDA warnings?

A: WebMD will alert users to the most important FDA warnings and alerts affecting consumers such as recalls, label changes and investigations. Not all FDA actions are included. Go to the FDA for a comprehensive list of warnings.

Q: Can I be alerted by email if there is an FDA warning or alert?

A: Yes. If you are signed in to WebMD.com and using My Medicine you can sign up to receive email alerts when you add a medicine. To unsubscribe click here.

Q: Can I add medicines for family members?

A: Yes. Click the arrow next to your picture to add drug profiles for family or loved ones.

Q: Can I access My Medicine from my mobile phone?

A: Yes. Sign in to the WebMD Mobile App. Your saved medicine can be found under “Saved.”

Q: Why are there already medicines saved when this my first time using this tool?

A: If you have previously saved a medication on WebMD, for example, in the WebMD Mobile App, these may display in My Medicine.

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Medicine – definition of medicine by The Free Dictionary

Quotations”Formerly, when religion was strong and science weak, men mistook magic for medicine; now, when science is strong and religion weak, men mistake medicine for magic” [Thomas Szasz The Second Skin]

Branches of medicine aetiology or etiology, anaesthetics, anaplasty, anatomy, andrology, angiology, audiology, aviation medicine, bacteriology, balneology, bioastronautics, biomedicine, cardiology, chiropody, dental hygiene or oral hygiene, dental surgery, dentistry, dermatology, diagnostics, eccrinology, electrophysiology, electrotherapeutics, embryology, encephalography, endocrinology, endodontics, epidemiology, exodontics, forensic or legal medicine, gastroenterology, genitourinary medicine, geratology, geriatrics, gerontology, gynaecology or (U.S.) gynecology, haematology or (U.S.) hematology, hydrotherapeutics, immunochemistry, immunology, industrial medicine, internal medicine, laryngology, materia medica, midwifery, morbid anatomy, myology, neonatology, nephrology, neuroanatomy, neuroendocrinology, neurology, neuropathology, neurophysiology, neuropsychiatry, neurosurgery, nosology, nostology, nuclear medicine, nutrition, obstetrics, odontology, oncology, ophthalmology, optometry, orthodontics or orthodontia, orthopaedics or (U.S.) orthopedics, orthoptics, orthotics, osteology, osteoplasty, otolaryngology, otology, paediatrics or (U.S.) pediatrics, pathology, periodontics, pharyngology, physical medicine, physiotherapy or (U.S.) physiatrics, plastic surgery, posology, preventive medicine, proctology, psychiatry, psychoanalysis, psychology, radiology, rheumatology, rhinology, serology, space medicine, spare-part surgery, speech therapy, sports medicine, stomatology, surgery, symptomatology, syphilology, therapeutics, tocology or tokology, toxicology, trichology, urology, venereology, veterinary science or medicine, virology

Medical practitioners and specialists aetiologist or etiologist, anaesthetist, anatomist, andrologist, audiologist, bacteriologist, balneologist, barefoot doctor, cardiologist, chiropodist, consultant, dental hygienist or oral hygienist, dentist or dental surgeon, dermatologist, diagnostician, dietitian, district nurse, doctor, electrophysiologist, embryologist, endocrinologist, endodontist, epidemiologist, exodontist, extern or externe (U.S. & Canad.), forensic scientist, gastroenterologist, general practitioner or GP, geriatrician or geriatrist, gerontologist, gynaecologist or (U.S.) gynecologist, haematologist or (U.S.) hematologist, health visitor, house physician, houseman, hydrotherapist, immunologist, intern or interne (U.S. & Canad.), internist, junior doctor, laboratory technician, laryngologist, matron, midwife, myologist, neonatologist, nephrologist, neuroanatomist, neurologist, neuropathologist, neurophysiologist, neuropsychiatrist, neurosurgeon, nosologist, nurse, nursing officer, nutritionist, obstetrician, occupational therapist, odontologist, oncologist, ophthalmologist, optician, optometrist, orderly, orthodontist, orthopaedist or (U.S.) orthopedist, orthoptist, orthotist, osteologist, otolaryngologist, otologist, paediatrician or (U.S.) pediatrician, paramedic, pathologist, pharyngologist, physiotherapist or physio, plastic surgeon, proctologist, psychiatrist, psychoanalyst, psychologist, radiographer, radiologist, registrar, resident (U.S. & Canad.), rheumatologist, rhinologist, serologist, speech therapist, surgeon, syphilologist, therapist, toxicologist, trichologist, urologist, venereologist, veterinary surgeon, vet or (U.S.) veterinarian, virologist

Medical and surgical instruments and equipment arthroscope, artificial heart, artificial kidney, aspirator, bandage, bedpan, bistoury, bronchoscope, cannula or canula, cardiograph, catheter, catling, clamp, clinical thermometer, colonoscope, colposcope, compressor, CT scanner or CAT scanner, curet or curette, cystoscope, defibrillator, depressor, dialysis machine, drain, electrocardiograph, electroencephalograph, electromyograph, encephalogram, endoscope, fetoscope, fibrescope or (U.S.) fiberscope, fluoroscope, forceps, gamma camera, gastroscope, gonioscope, haemostat or (U.S.) hemostat, heart-lung machine, heat lamp, hypodermic or hypodermic needle, hypodermic or hypodermic syringe, inhalator, inspirator, iron lung, kidney machine, kymograph or cymograph, lancet or lance, laparoscope, laryngoscope, life-support machine, microscope, nebulizer, needle, nephroscope, oesophagoscope or (U.S.) esophagoscope, ophthalmoscope, orthoscope, otoscope, oxygen mask, oxygen tent, pacemaker, packing, perimeter, pharyngoscope, plaster cast, pneumatometer, pneumograph, probe, proctoscope, Pulmotor (trademark), raspatory, respirator, resuscitator, retinoscope, retractor, rheometer, rhinoscope, roentgenoscope or rntgenoscope, scalpel, scanner, skiascope, sling, sound, specimen bottle, speculum, sphygmograph, sphygmomanometer, spirograph, spirometer, splint, stethoscope, stomach pump, stretcher, stupe, stylet, styptic pencil, suture, swab, syringe, thoracoscope, tourniquet, trepan, trephine, trocar, ultrasound scanner, urethroscope, urinometer, ventilator, wet pack, X-ray machine

Branches of alternative medicine acupressure, acupuncture, Alexander technique, aromatherapy, autogenic training, Bach flower remedy, biofeedback, chiropractic, herbalism, homeopathy or homoeopathy, hydrotherapy, hypnosis, hypnotherapy, iridology, kinesiology, massage, moxibustion, naturopathy, osteopathy, radionics, reflexology, shiatsu

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Medicine – definition of medicine by The Free Dictionary

medicine | Definition, Fields, Research, & Facts | Britannica.com

Organization of health services

It is generally the goal of most countries to have their health services organized in such a way to ensure that individuals, families, and communities obtain the maximum benefit from current knowledge and technology available for the promotion, maintenance, and restoration of health. In order to play their part in this process, governments and other agencies are faced with numerous tasks, including the following: (1) They must obtain as much information as is possible on the size, extent, and urgency of their needs; without accurate information, planning can be misdirected. (2) These needs must then be revised against the resources likely to be available in terms of money, manpower, and materials; developing countries may well require external aid to supplement their own resources. (3) Based on their assessments, countries then need to determine realistic objectives and draw up plans. (4) Finally, a process of evaluation needs to be built into the program; the lack of reliable information and accurate assessment can lead to confusion, waste, and inefficiency.

Health services of any nature reflect a number of interrelated characteristics, among which the most obvious, but not necessarily the most important from a national point of view, is the curative function; that is to say, caring for those already ill. Others include special services that deal with particular groups (such as children or pregnant women) and with specific needs such as nutrition or immunization; preventive services, the protection of the health both of individuals and of communities; health education; and, as mentioned above, the collection and analysis of information.

In the curative domain there are various forms of medical practice. They may be thought of generally as forming a pyramidal structure, with three tiers representing increasing degrees of specialization and technical sophistication but catering to diminishing numbers of patients as they are filtered out of the system at a lower level. Only those patients who require special attention either for diagnosis or treatment should reach the second (advisory) or third (specialized treatment) tiers where the cost per item of service becomes increasingly higher. The first level represents primary health care, or first contact care, at which patients have their initial contact with the health-care system.

Primary health care is an integral part of a countrys health maintenance system, of which it forms the largest and most important part. As described in the declaration of Alma-Ata, primary health care should be based on practical, scientifically sound and socially acceptable methods and technology made universally accessible to individuals and families in the community through their full participation and at a cost that the community and country can afford to maintain at every stage of their development. Primary health care in the developed countries is usually the province of a medically qualified physician; in the developing countries first contact care is often provided by nonmedically qualified personnel.

The vast majority of patients can be fully dealt with at the primary level. Those who cannot are referred to the second tier (secondary health care, or the referral services) for the opinion of a consultant with specialized knowledge or for X-ray examinations and special tests. Secondary health care often requires the technology offered by a local or regional hospital. Increasingly, however, the radiological and laboratory services provided by hospitals are available directly to the family doctor, thus improving his service to patients and increasing its range. The third tier of health care, employing specialist services, is offered by institutions such as teaching hospitals and units devoted to the care of particular groupswomen, children, patients with mental disorders, and so on. The dramatic differences in the cost of treatment at the various levels is a matter of particular importance in developing countries, where the cost of treatment for patients at the primary health-care level is usually only a small fraction of that at the third level; medical costs at any level in such countries, however, are usually borne by the government.

Ideally, provision of health care at all levels will be available to all patients; such health care may be said to be universal. The well-off, both in relatively wealthy industrialized countries and in the poorer developing world, may be able to get medical attention from sources they prefer and can pay for in the private sector. The vast majority of people in most countries, however, are dependent in various ways upon health services provided by the state, to which they may contribute comparatively little or, in the case of poor countries, nothing at all.

The costs to national economics of providing health care are considerable and have been growing at a rapidly increasing rate, especially in countries such as the United States, Germany, and Sweden; the rise in Britain has been less rapid. This trend has been the cause of major concerns in both developed and developing countries. Some of this concern is based upon the lack of any consistent evidence to show that more spending on health care produces better health. There is a movement in developing countries to replace the type of organization of health-care services that evolved during European colonial times with some less expensive, and for them, more appropriate, health-care system.

In the industrialized world the growing cost of health services has caused both private and public health-care delivery systems to question current policies and to seek more economical methods of achieving their goals. Despite expenditures, health services are not always used effectively by those who need them, and results can vary widely from community to community. In Britain, for example, between 1951 and 1971 the death rate fell by 24 percent in the wealthier sections of the population but by only half that in the most underprivileged sections of society. The achievement of good health is reliant upon more than just the quality of health care. Health entails such factors as good education, safe working conditions, a favourable environment, amenities in the home, well-integrated social services, and reasonable standards of living.

The developing countries differ from one another culturally, socially, and economically, but what they have in common is a low average income per person, with large percentages of their populations living at or below the poverty level. Although most have a small elite class, living mainly in the cities, the largest part of their populations live in rural areas. Urban regions in developing and some developed countries in the mid- and late 20th century have developed pockets of slums, which are growing because of an influx of rural peoples. For lack of even the simplest measures, vast numbers of urban and rural poor die each year of preventable and curable diseases, often associated with poor hygiene and sanitation, impure water supplies, malnutrition, vitamin deficiencies, and chronic preventable infections. The effect of these and other deprivations is reflected by the finding that in the 1980s the life expectancy at birth for men and women was about one-third less in Africa than it was in Europe; similarly, infant mortality in Africa was about eight times greater than in Europe. The extension of primary health-care services is therefore a high priority in the developing countries.

The developing countries themselves, lacking the proper resources, have often been unable to generate or implement the plans necessary to provide required services at the village or urban poor level. It has, however, become clear that the system of health care that is appropriate for one country is often unsuitable for another. Research has established that effective health care is related to the special circumstances of the individual country, its people, culture, ideology, and economic and natural resources.

The rising costs of providing health care have influenced a trend, especially among the developing nations, to promote services that employ less highly trained primary health-care personnel who can be distributed more widely in order to reach the largest possible proportion of the community. The principal medical problems to be dealt with in the developing world include undernutrition, infection, gastrointestinal disorders, and respiratory complaints, which themselves may be the result of poverty, ignorance, and poor hygiene. For the most part, these are easy to identify and to treat. Furthermore, preventive measures are usually simple and cheap. Neither treatment nor prevention requires extensive professional training: in most cases they can be dealt with adequately by the primary health worker, a term that includes all nonprofessional health personnel.

Those concerned with providing health care in the developed countries face a different set of problems. The diseases so prevalent in the Third World have, for the most part, been eliminated or are readily treatable. Many of the adverse environmental conditions and public health hazards have been conquered. Social services of varying degrees of adequacy have been provided. Public funds can be called upon to support the cost of medical care, and there are a variety of private insurance plans available to the consumer. Nevertheless, the funds that a government can devote to health care are limited and the cost of modern medicine continues to increase, thus putting adequate medical services beyond the reach of many. Adding to the expense of modern medical practices is the increasing demand for greater funding of health education and preventive measures specifically directed toward the poor.

In many parts of the world, particularly in developing countries, people get their primary health care, or first-contact care, where available at all, from nonmedically qualified personnel; these cadres of medical auxiliaries are being trained in increasing numbers to meet overwhelming needs among rapidly growing populations. Even among the comparatively wealthy countries of the world, containing in all a much smaller percentage of the worlds population, escalation in the costs of health services and in the cost of training a physician has precipitated some movement toward reappraisal of the role of the medical doctor in the delivery of first-contact care.

In advanced industrial countries, however, it is usually a trained physician who is called upon to provide the first-contact care. The patient seeking first-contact care can go either to a general practitioner or turn directly to a specialist. Which is the wisest choice has become a subject of some controversy. The general practitioner, however, is becoming rather rare in some developed countries. In countries where he does still exist, he is being increasingly observed as an obsolescent figure, because medicine covers an immense, rapidly changing, and complex field of which no physician can possibly master more than a small fraction. The very concept of the general practitioner, it is thus argued, may be absurd.

The obvious alternative to general practice is the direct access of a patient to a specialist. If a patient has problems with vision, he goes to an eye specialist, and if he has a pain in his chest (which he fears is due to his heart), he goes to a heart specialist. One objection to this plan is that the patient often cannot know which organ is responsible for his symptoms, and the most careful physician, after doing many investigations, may remain uncertain as to the cause. Breathlessnessa common symptommay be due to heart disease, to lung disease, to anemia, or to emotional upset. Another common symptom is general malaisefeeling run-down or always tired; others are headache, chronic low backache, rheumatism, abdominal discomfort, poor appetite, and constipation. Some patients may also be overtly anxious or depressed. Among the most subtle medical skills is the ability to assess people with such symptoms and to distinguish between symptoms that are caused predominantly by emotional upset and those that are predominantly of bodily origin. A specialist may be capable of such a general assessment, but, often, with emphasis on his own subject, he fails at this point. The generalist with his broader training is often the better choice for a first diagnosis, with referral to a specialist as the next option.

It is often felt that there are also practical advantages for the patient in having his own doctor, who knows about his background, who has seen him through various illnesses, and who has often looked after his family as well. This personal physician, often a generalist, is in the best position to decide when the patient should be referred to a consultant.

The advantages of general practice and specialization are combined when the physician of first contact is a pediatrician. Although he sees only children and thus acquires a special knowledge of childhood maladies, he remains a generalist who looks at the whole patient. Another combination of general practice and specialization is represented by group practice, the members of which partially or fully specialize. One or more may be general practitioners, and one may be a surgeon, a second an obstetrician, a third a pediatrician, and a fourth an internist. In isolated communities group practice may be a satisfactory compromise, but in urban regions, where nearly everyone can be sent quickly to a hospital, the specialist surgeon working in a fully equipped hospital can usually provide better treatment than a general practitioner surgeon in a small clinic hospital.

Before 1948, general practitioners in Britain settled where they could make a living. Patients fell into two main groups: weekly wage earners, who were compulsorily insured, were on a doctors panel and were given free medical attention (for which the doctor was paid quarterly by the government); most of the remainder paid the doctor a fee for service at the time of the illness. In 1948 the National Health Service began operation. Under its provisions, everyone is entitled to free medical attention with a general practitioner with whom he is registered. Though general practitioners in the National Health Service are not debarred from also having private patients, these must be people who are not registered with them under the National Health Service. Any physician is free to work as a general practitioner entirely independent of the National Health Service, though there are few who do so. Almost the entire population is registered with a National Health Service general practitioner, and the vast majority automatically sees this physician, or one of his partners, when they require medical attention. A few people, mostly wealthy, while registered with a National Health Service general practitioner, regularly see another physician privately; and a few may occasionally seek a private consultation because they are dissatisfied with their National Health Service physician.

A general practitioner under the National Health Service remains an independent contractor, paid by a capitation fee; that is, according to the number of people registered with him. He may work entirely from his own office, and he provides and pays his own receptionist, secretary, and other ancillary staff. Most general practitioners have one or more partners and work more and more in premises built for the purpose. Some of these structures are erected by the physicians themselves, but many are provided by the local authority, the physicians paying rent for using them. Health centres, in which groups of general practitioners work have become common.

In Britain only a small minority of general practitioners can admit patients to a hospital and look after them personally. Most of this minority are in country districts, where, before the days of the National Health Service, there were cottage hospitals run by general practitioners; many of these hospitals continued to function in a similar manner. All general practitioners use such hospital facilities as X-ray departments and laboratories, and many general practitioners work in hospitals in emergency rooms (casualty departments) or as clinical assistants to consultants, or specialists.

General practitioners are spread more evenly over the country than formerly, when there were many in the richer areas and few in the industrial towns. The maximum allowed list of National Health Service patients per doctor is 3,500; the average is about 2,500. Patients have free choice of the physician with whom they register, with the proviso that they cannot be accepted by one who already has a full list and that a physician can refuse to accept them (though such refusals are rare). In remote rural places there may be only one physician within a reasonable distance.

Until the mid-20th century it was not unusual for the doctor in Britain to visit patients in their own homes. A general practitioner might make 15 or 20 such house calls in a day, as well as seeing patients in his office or surgery, often in the evenings. This enabled him to become a family doctor in fact as well as in name. In modern practice, however, a home visit is quite exceptional and is paid only to the severely disabled or seriously ill when other recourses are ruled out. All patients are normally required to go to the doctor.

It has also become unusual for a personal doctor to be available during weekends or holidays. His place may be taken by one of his partners in a group practice, a provision that is reasonably satisfactory. General practitioners, however, may now use one of several commercial deputizing services that employs young doctors to be on call. Although some of these young doctors may be well experienced, patients do not generally appreciate this kind of arrangement.

Whereas in Britain the doctor of first contact is regularly a general practitioner, in the United States the nature of first-contact care is less consistent. General practice in the United States has been in a state of decline in the second half of the 20th century, especially in metropolitan areas. The general practitioner, however, is being replaced to some degree by the growing field of family practice. In 1969 family practice was recognized as a medical specialty after the American Academy of General Practice (now the American Academy of Family Physicians) and the American Medical Association created the American Board of General (now Family) Practice. Since that time the field has become one of the larger medical specialties in the United States. The family physicians were the first group of medical specialists in the United States for whom recertification was required.

There is no national health service, as such, in the United States. Most physicians in the country have traditionally been in some form of private practice, whether seeing patients in their own offices, clinics, medical centres, or another type of facility and regardless of the patients income. Doctors are usually compensated by such state and federally supported agencies as Medicaid (for treating the poor) and Medicare (for treating the elderly); not all doctors, however, accept poor patients. There are also some state-supported clinics and hospitals where the poor and elderly may receive free or low-cost treatment, and some doctors devote a small percentage of their time to treatment of the indigent. Veterans may receive free treatment at Veterans Administration hospitals, and the federal government through its Indian Health Service provides medical services to American Indians and Alaskan natives, sometimes using trained auxiliaries for first-contact care.

In the rural United States first-contact care is likely to come from a generalist. The middle- and upper-income groups living in urban areas, however, have access to a larger number of primary medical care options. Children are often taken to pediatricians, who may oversee the childs health needs until adulthood. Adults frequently make their initial contact with an internist, whose field is mainly that of medical (as opposed to surgical) illnesses; the internist often becomes the family physician. Other adults choose to go directly to physicians with narrower specialties, including dermatologists, allergists, gynecologists, orthopedists, and ophthalmologists.

Patients in the United States may also choose to be treated by doctors of osteopathy. These doctors are fully qualified, but they make up only a small percentage of the countrys physicians. They may also branch off into specialties, but general practice is much more common in their group than among M.D.s.

It used to be more common in the United States for physicians providing primary care to work independently, providing their own equipment and paying their own ancillary staff. In smaller cities they mostly had full hospital privileges, but in larger cities these privileges were more likely to be restricted. Physicians, often sharing the same specialties, are increasingly entering into group associations, where the expenses of office space, staff, and equipment may be shared; such associations may work out of suites of offices, clinics, or medical centres. The increasing competition and risks of private practice have caused many physicians to join Health Maintenance Organizations (HMOs), which provide comprehensive medical care and hospital care on a prepaid basis. The cost savings to patients are considerable, but they must use only the HMO doctors and facilities. HMOs stress preventive medicine and out-patient treatment as opposed to hospitalization as a means of reducing costs, a policy that has caused an increased number of empty hospital beds in the United States.

While the number of doctors per 100,000 population in the United States has been steadily increasing, there has been a trend among physicians toward the use of trained medical personnel to handle some of the basic services normally performed by the doctor. So-called physician extender services are commonly divided into nurse practitioners and physicians assistants, both of whom provide similar ancillary services for the general practitioner or specialist. Such personnel do not replace the doctor. Almost all American physicians have systems for taking each others calls when they become unavailable. House calls in the United States, as in Britain, have become exceedingly rare.

In Russia general practitioners are prevalent in the thinly populated rural areas. Pediatricians deal with children up to about age 15. Internists look after the medical ills of adults, and occupational physicians deal with the workers, sharing care with internists.

Teams of physicians with experience in varying specialties work from polyclinics or outpatient units, where many types of diseases are treated. Small towns usually have one polyclinic to serve all purposes. Large cities commonly have separate polyclinics for children and adults, as well as clinics with specializations such as womens health care, mental illnesses, and sexually transmitted diseases. Polyclinics usually have X-ray apparatus and facilities for examination of tissue specimens, facilities associated with the departments of the district hospital. Beginning in the late 1970s was a trend toward the development of more large, multipurpose treatment centres, first-aid hospitals, and specialized medicine and health care centres.

Home visits have traditionally been common, and much of the physicians time is spent in performing routine checkups for preventive purposes. Some patients in sparsely populated rural areas may be seen first by feldshers (auxiliary health workers), nurses, or midwives who work under the supervision of a polyclinic or hospital physician. The feldsher was once a lower-grade physician in the army or peasant communities, but feldshers are now regarded as paramedical workers.

In Japan, with less rigid legal restriction of the sale of pharmaceuticals than in the West, there was formerly a strong tradition of self-medication and self-treatment. This was modified in 1961 by the institution of health insurance programs that covered a large proportion of the population; there was then a great increase in visits to the outpatient clinics of hospitals and to private clinics and individual physicians.

When Japan shifted from traditional Chinese medicine with the adoption of Western medical practices in the 1870s, Germany became the chief model. As a result of German influence and of their own traditions, Japanese physicians tended to prefer professorial status and scholarly research opportunities at the universities or positions in the national or prefectural hospitals to private practice. There were some pioneering physicians, however, who brought medical care to the ordinary people.

Physicians in Japan have tended to cluster in the urban areas. The Medical Service Law of 1963 was amended to empower the Ministry of Health and Welfare to control the planning and distribution of future public and nonprofit medical facilities, partly to redress the urban-rural imbalance. Meanwhile, mobile services were expanded.

The influx of patients into hospitals and private clinics after the passage of the national health insurance acts of 1961 had, as one effect, a severe reduction in the amount of time available for any one patient. Perhaps in reaction to this situation, there has been a modest resurgence in the popularity of traditional Chinese medicine, with its leisurely interview, its dependence on herbal and other natural medicines, and its other traditional diagnostic and therapeutic practices. The rapid aging of the Japanese population as a result of the sharply decreasing death rate and birth rate has created an urgent need for expanded health care services for the elderly. There has also been an increasing need for centres to treat health problems resulting from environmental causes.

On the continent of Europe there are great differences both within single countries and between countries in the kinds of first-contact medical care. General practice, while declining in Europe as elsewhere, is still rather common even in some large cities, as well as in remote country areas.

In The Netherlands, departments of general practice are administered by general practitioners in all the medical schoolsan exceptional state of affairsand general practice flourishes. In the larger cities of Denmark, general practice on an individual basis is usual and popular, because the physician works only during office hours. In addition, there is a duty doctor service for nights and weekends. In the cities of Sweden, primary care is given by specialists. In the remote regions of northern Sweden, district doctors act as general practitioners to patients spread over huge areas; the district doctors delegate much of their home visiting to nurses.

In France there are still general practitioners, but their number is declining. Many medical practitioners advertise themselves directly to the public as specialists in internal medicine, ophthalmologists, gynecologists, and other kinds of specialists. Even when patients have a general practitioner, they may still go directly to a specialist. Attempts to stem the decline in general practice are being made by the development of group practice and of small rural hospitals equipped to deal with less serious illnesses, where general practitioners can look after their patients.

Although Israel has a high ratio of physicians to population, there is a shortage of general practitioners, and only in rural areas is general practice common. In the towns many people go directly to pediatricians, gynecologists, and other specialists, but there has been a reaction against this direct access to the specialist. More general practitioners have been trained, and the Israel Medical Association has recommended that no patient should be referred to a specialist except by the family physician or on instructions given by the family nurse. At Tel Aviv University there is a department of family medicine. In some newly developing areas, where the doctor shortage is greatest, there are medical centres at which all patients are initially interviewed by a nurse. The nurse may deal with many minor ailments, thus freeing the physician to treat the more seriously ill.

Nearly half the medical doctors in Australia are general practitionersa far higher proportion than in most other advanced countriesthough, as elsewhere, their numbers are declining. They tend to do far more for their patients than in Britain, many performing such operations as removal of the appendix, gallbladder, or uterus, operations that elsewhere would be carried out by a specialist surgeon. Group practices are common.

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Future Physicians Meet Their Match

Its a moment when lives are changed and career paths determined. More than 300 students from the four campuses of the University of Illinois College of Medicine learned their residency placements on Friday, March 15, during Match Day 2019.

This is a pretty awesome way to start a new job, UI COM Executive Dean Mark Rosenblatt told the students moments before they, and thousands across the country, opened their envelopes simultaneously at 11 a.m. With you at the helm, the future of medicine is truly bright.

Learn about the unforgettable moments at the Chicago campus, the Peoria campus, the Rockford campus, and the Urbana campus.

SAVE THE DATE2019 College of Medicine Research Forum

The 2019 College of Medicine Research Forum will be held Friday, November 22, 2019. There were over 150 participants and research poster presentations at last years events.

Please click here or visit College of Medicine Research page for a complete list of winners and pictures from the event.

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Medicine | Define Medicine at Dictionary.com

n.

c.1200, “medical treatment, cure, remedy,” also used figuratively, of spiritual remedies, from Old French medecine (Modern French mdicine) “medicine, art of healing, cure, treatment, potion,” from Latin medicina “the healing art, medicine; a remedy,” also used figuratively, perhaps originally ars medicina “the medical art,” from fem. of medicinus (adj.) “of a doctor,” from medicus “a physician” (see medical); though OED finds evidence for this is wanting. Meaning “a medicinal potion or plaster” in English is mid-14c.

To take (one’s) medicine “submit to something disagreeable” is first recorded 1865. North American Indian medicine-man “shaman” is first attested 1801, from American Indian adoption of the word medicine in sense of “magical influence.” The U.S.-Canadian boundary they called Medicine Line (first attested 1910), because it conferred a kind of magic protection: punishment for crimes committed on one side of it could be avoided by crossing over to the other. Medicine show “traveling show meant to attract a crowd so patent medicine can be sold to them” is American English, 1938. Medicine ball “stuffed leather ball used for exercise” is from 1889.

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Posted today in FDA Alerts

Investigation ongoing This page to be updated as more information is availableIMPORTANT: Medications containing only amlodipine or hydrochlorothiazide (HCTZ) are not being recalled. Manufacturers are recalling medications containing amlodipine in combination with valsartan or losartan, and medications containing hydrochlorothiazide HCTZ in combination…

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— More than 20 percent of adults in the United States report having at least one tattoo.Because ink is injected into the skin, the Centers for Disease Control and Prevention urges consumers to be wary of the ink’s origin. Manufacturers may use unsuitable inks (calligraphy, drawing or printer ink) to make products for tattooing.To reduce the risk…

Posted yesterday in New Drug Approvals

Jazz Pharmaceuticals plc today announced that the U.S. Food and Drug Administration (FDA) approved Sunosi (solriamfetol) to improve wakefulness in adult patients with excessive daytime sleepiness associated with narcolepsy or obstructive sleep apnea (OSA). Once-daily Sunosi is approved with doses of 75 mg and 150 mg for patients with narcolepsy and…

Posted 3 days ago in New Drug Approvals

The U.S. Food and Drug Administration today approved Zulresso (brexanolone) injection for intravenous (IV) use for the treatment of postpartum depression (PPD) in adult women. This is the first drug approved by the FDA specifically for PPD.”Postpartum depression is a serious condition that, when severe, can be life-threatening. Women may…

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— About 1 in 3 Americans between the ages of 65 and 74 has hearing loss. And about half of those over 75 have trouble hearing.Though age-related hearing loss is difficult to prevent, noise-induced hearing loss can be minimized. People should actively reduce exposure to loud noise, the U.S. National Institute on Deafness and Other Communication Disorders…

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Recent research shows that eggs can be part of a healthful diet.Eggs are highly nutritious because they deliver the essential amino acids your body needs to build and repair muscle and help keep your metabolism humming. Egg yolks in particular contain many nutrients, including vitamin A, B vitamins and hard-to-get vitamin D.Whether white or brown,…

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It’s never too soon to teach kids to be culturally competent — to learn about, respect and accept people whose culture is different from their own.Children as young as 2 start to become aware of differences among people — starting with gender — and to be sensitive to attitudes held by those around them. Experts believe that a child’s cultural attitudes…

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Expectant moms often try to plan as many aspects of their upcoming delivery as they can. But one thing they might not consider is what type of pain relief they will choose if they need to have a C-section.Now, new research from the University of Texas suggests that while opioids can control pain, a combination of other painkillers could offer similar…

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Tipping the scales at 233 pounds, Charles Joy realized he needed to make some changes.The 28-year-old Louisville, Kentucky, native already had tried many diet plans to varying degrees of success. In 2013, he lost more than 100 pounds through exercise and diet. But afterward, his weight slowly began to creep back up.In 2017, Joy decided to try time-restricted…

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Gun-related deaths among school-age children in the United States are increasing at alarming rates, researchers report.In 2017, gun violence claimed more 5- to 18-year-olds than police officers or active-duty members of the U.S. military, according to a chilling new study led by investigators from Florida Atlantic University.”It is sobering that in…

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If you take medication for blood pressure or heart failure, chances are you have been affected by, or at least heard of, the recent recall of over 75 different generics of valsartan, losartan, and irbesartan and their combinations. 75 different generics? But how can so many different manufacturers be affected when the FDA strictly oversees []

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Many people believe HIV started sometime in the 1980s in the United States. But this is not true. In fact, the first acquisition of HIV most likely happened in the 1920s, in the Democratic Republic of Congos (DRC) capital, Kinshasa, as a result of an adaption of the Simian Immunodeficiency Virus (SIV) that was able []

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Becoming a parent is a wonderful, amazing experience. But it can also be a confusing and overwhelming one too. Firstly, theres constant worry over whether your baby is sleeping, feeding, or pooping enough or too much. Secondly, theres a whole range of never-heard-of-before conditions to deal with such as baby acne, colic, cradle cap, diaper []

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Organization of health services

It is generally the goal of most countries to have their health services organized in such a way to ensure that individuals, families, and communities obtain the maximum benefit from current knowledge and technology available for the promotion, maintenance, and restoration of health. In order to play their part in this process, governments and other agencies are faced with numerous tasks, including the following: (1) They must obtain as much information as is possible on the size, extent, and urgency of their needs; without accurate information, planning can be misdirected. (2) These needs must then be revised against the resources likely to be available in terms of money, manpower, and materials; developing countries may well require external aid to supplement their own resources. (3) Based on their assessments, countries then need to determine realistic objectives and draw up plans. (4) Finally, a process of evaluation needs to be built into the program; the lack of reliable information and accurate assessment can lead to confusion, waste, and inefficiency.

Health services of any nature reflect a number of interrelated characteristics, among which the most obvious, but not necessarily the most important from a national point of view, is the curative function; that is to say, caring for those already ill. Others include special services that deal with particular groups (such as children or pregnant women) and with specific needs such as nutrition or immunization; preventive services, the protection of the health both of individuals and of communities; health education; and, as mentioned above, the collection and analysis of information.

In the curative domain there are various forms of medical practice. They may be thought of generally as forming a pyramidal structure, with three tiers representing increasing degrees of specialization and technical sophistication but catering to diminishing numbers of patients as they are filtered out of the system at a lower level. Only those patients who require special attention either for diagnosis or treatment should reach the second (advisory) or third (specialized treatment) tiers where the cost per item of service becomes increasingly higher. The first level represents primary health care, or first contact care, at which patients have their initial contact with the health-care system.

Primary health care is an integral part of a countrys health maintenance system, of which it forms the largest and most important part. As described in the declaration of Alma-Ata, primary health care should be based on practical, scientifically sound and socially acceptable methods and technology made universally accessible to individuals and families in the community through their full participation and at a cost that the community and country can afford to maintain at every stage of their development. Primary health care in the developed countries is usually the province of a medically qualified physician; in the developing countries first contact care is often provided by nonmedically qualified personnel.

The vast majority of patients can be fully dealt with at the primary level. Those who cannot are referred to the second tier (secondary health care, or the referral services) for the opinion of a consultant with specialized knowledge or for X-ray examinations and special tests. Secondary health care often requires the technology offered by a local or regional hospital. Increasingly, however, the radiological and laboratory services provided by hospitals are available directly to the family doctor, thus improving his service to patients and increasing its range. The third tier of health care, employing specialist services, is offered by institutions such as teaching hospitals and units devoted to the care of particular groupswomen, children, patients with mental disorders, and so on. The dramatic differences in the cost of treatment at the various levels is a matter of particular importance in developing countries, where the cost of treatment for patients at the primary health-care level is usually only a small fraction of that at the third level; medical costs at any level in such countries, however, are usually borne by the government.

Ideally, provision of health care at all levels will be available to all patients; such health care may be said to be universal. The well-off, both in relatively wealthy industrialized countries and in the poorer developing world, may be able to get medical attention from sources they prefer and can pay for in the private sector. The vast majority of people in most countries, however, are dependent in various ways upon health services provided by the state, to which they may contribute comparatively little or, in the case of poor countries, nothing at all.

The costs to national economics of providing health care are considerable and have been growing at a rapidly increasing rate, especially in countries such as the United States, Germany, and Sweden; the rise in Britain has been less rapid. This trend has been the cause of major concerns in both developed and developing countries. Some of this concern is based upon the lack of any consistent evidence to show that more spending on health care produces better health. There is a movement in developing countries to replace the type of organization of health-care services that evolved during European colonial times with some less expensive, and for them, more appropriate, health-care system.

In the industrialized world the growing cost of health services has caused both private and public health-care delivery systems to question current policies and to seek more economical methods of achieving their goals. Despite expenditures, health services are not always used effectively by those who need them, and results can vary widely from community to community. In Britain, for example, between 1951 and 1971 the death rate fell by 24 percent in the wealthier sections of the population but by only half that in the most underprivileged sections of society. The achievement of good health is reliant upon more than just the quality of health care. Health entails such factors as good education, safe working conditions, a favourable environment, amenities in the home, well-integrated social services, and reasonable standards of living.

The developing countries differ from one another culturally, socially, and economically, but what they have in common is a low average income per person, with large percentages of their populations living at or below the poverty level. Although most have a small elite class, living mainly in the cities, the largest part of their populations live in rural areas. Urban regions in developing and some developed countries in the mid- and late 20th century have developed pockets of slums, which are growing because of an influx of rural peoples. For lack of even the simplest measures, vast numbers of urban and rural poor die each year of preventable and curable diseases, often associated with poor hygiene and sanitation, impure water supplies, malnutrition, vitamin deficiencies, and chronic preventable infections. The effect of these and other deprivations is reflected by the finding that in the 1980s the life expectancy at birth for men and women was about one-third less in Africa than it was in Europe; similarly, infant mortality in Africa was about eight times greater than in Europe. The extension of primary health-care services is therefore a high priority in the developing countries.

The developing countries themselves, lacking the proper resources, have often been unable to generate or implement the plans necessary to provide required services at the village or urban poor level. It has, however, become clear that the system of health care that is appropriate for one country is often unsuitable for another. Research has established that effective health care is related to the special circumstances of the individual country, its people, culture, ideology, and economic and natural resources.

The rising costs of providing health care have influenced a trend, especially among the developing nations, to promote services that employ less highly trained primary health-care personnel who can be distributed more widely in order to reach the largest possible proportion of the community. The principal medical problems to be dealt with in the developing world include undernutrition, infection, gastrointestinal disorders, and respiratory complaints, which themselves may be the result of poverty, ignorance, and poor hygiene. For the most part, these are easy to identify and to treat. Furthermore, preventive measures are usually simple and cheap. Neither treatment nor prevention requires extensive professional training: in most cases they can be dealt with adequately by the primary health worker, a term that includes all nonprofessional health personnel.

Those concerned with providing health care in the developed countries face a different set of problems. The diseases so prevalent in the Third World have, for the most part, been eliminated or are readily treatable. Many of the adverse environmental conditions and public health hazards have been conquered. Social services of varying degrees of adequacy have been provided. Public funds can be called upon to support the cost of medical care, and there are a variety of private insurance plans available to the consumer. Nevertheless, the funds that a government can devote to health care are limited and the cost of modern medicine continues to increase, thus putting adequate medical services beyond the reach of many. Adding to the expense of modern medical practices is the increasing demand for greater funding of health education and preventive measures specifically directed toward the poor.

In many parts of the world, particularly in developing countries, people get their primary health care, or first-contact care, where available at all, from nonmedically qualified personnel; these cadres of medical auxiliaries are being trained in increasing numbers to meet overwhelming needs among rapidly growing populations. Even among the comparatively wealthy countries of the world, containing in all a much smaller percentage of the worlds population, escalation in the costs of health services and in the cost of training a physician has precipitated some movement toward reappraisal of the role of the medical doctor in the delivery of first-contact care.

In advanced industrial countries, however, it is usually a trained physician who is called upon to provide the first-contact care. The patient seeking first-contact care can go either to a general practitioner or turn directly to a specialist. Which is the wisest choice has become a subject of some controversy. The general practitioner, however, is becoming rather rare in some developed countries. In countries where he does still exist, he is being increasingly observed as an obsolescent figure, because medicine covers an immense, rapidly changing, and complex field of which no physician can possibly master more than a small fraction. The very concept of the general practitioner, it is thus argued, may be absurd.

The obvious alternative to general practice is the direct access of a patient to a specialist. If a patient has problems with vision, he goes to an eye specialist, and if he has a pain in his chest (which he fears is due to his heart), he goes to a heart specialist. One objection to this plan is that the patient often cannot know which organ is responsible for his symptoms, and the most careful physician, after doing many investigations, may remain uncertain as to the cause. Breathlessnessa common symptommay be due to heart disease, to lung disease, to anemia, or to emotional upset. Another common symptom is general malaisefeeling run-down or always tired; others are headache, chronic low backache, rheumatism, abdominal discomfort, poor appetite, and constipation. Some patients may also be overtly anxious or depressed. Among the most subtle medical skills is the ability to assess people with such symptoms and to distinguish between symptoms that are caused predominantly by emotional upset and those that are predominantly of bodily origin. A specialist may be capable of such a general assessment, but, often, with emphasis on his own subject, he fails at this point. The generalist with his broader training is often the better choice for a first diagnosis, with referral to a specialist as the next option.

It is often felt that there are also practical advantages for the patient in having his own doctor, who knows about his background, who has seen him through various illnesses, and who has often looked after his family as well. This personal physician, often a generalist, is in the best position to decide when the patient should be referred to a consultant.

The advantages of general practice and specialization are combined when the physician of first contact is a pediatrician. Although he sees only children and thus acquires a special knowledge of childhood maladies, he remains a generalist who looks at the whole patient. Another combination of general practice and specialization is represented by group practice, the members of which partially or fully specialize. One or more may be general practitioners, and one may be a surgeon, a second an obstetrician, a third a pediatrician, and a fourth an internist. In isolated communities group practice may be a satisfactory compromise, but in urban regions, where nearly everyone can be sent quickly to a hospital, the specialist surgeon working in a fully equipped hospital can usually provide better treatment than a general practitioner surgeon in a small clinic hospital.

Before 1948, general practitioners in Britain settled where they could make a living. Patients fell into two main groups: weekly wage earners, who were compulsorily insured, were on a doctors panel and were given free medical attention (for which the doctor was paid quarterly by the government); most of the remainder paid the doctor a fee for service at the time of the illness. In 1948 the National Health Service began operation. Under its provisions, everyone is entitled to free medical attention with a general practitioner with whom he is registered. Though general practitioners in the National Health Service are not debarred from also having private patients, these must be people who are not registered with them under the National Health Service. Any physician is free to work as a general practitioner entirely independent of the National Health Service, though there are few who do so. Almost the entire population is registered with a National Health Service general practitioner, and the vast majority automatically sees this physician, or one of his partners, when they require medical attention. A few people, mostly wealthy, while registered with a National Health Service general practitioner, regularly see another physician privately; and a few may occasionally seek a private consultation because they are dissatisfied with their National Health Service physician.

A general practitioner under the National Health Service remains an independent contractor, paid by a capitation fee; that is, according to the number of people registered with him. He may work entirely from his own office, and he provides and pays his own receptionist, secretary, and other ancillary staff. Most general practitioners have one or more partners and work more and more in premises built for the purpose. Some of these structures are erected by the physicians themselves, but many are provided by the local authority, the physicians paying rent for using them. Health centres, in which groups of general practitioners work have become common.

In Britain only a small minority of general practitioners can admit patients to a hospital and look after them personally. Most of this minority are in country districts, where, before the days of the National Health Service, there were cottage hospitals run by general practitioners; many of these hospitals continued to function in a similar manner. All general practitioners use such hospital facilities as X-ray departments and laboratories, and many general practitioners work in hospitals in emergency rooms (casualty departments) or as clinical assistants to consultants, or specialists.

General practitioners are spread more evenly over the country than formerly, when there were many in the richer areas and few in the industrial towns. The maximum allowed list of National Health Service patients per doctor is 3,500; the average is about 2,500. Patients have free choice of the physician with whom they register, with the proviso that they cannot be accepted by one who already has a full list and that a physician can refuse to accept them (though such refusals are rare). In remote rural places there may be only one physician within a reasonable distance.

Until the mid-20th century it was not unusual for the doctor in Britain to visit patients in their own homes. A general practitioner might make 15 or 20 such house calls in a day, as well as seeing patients in his office or surgery, often in the evenings. This enabled him to become a family doctor in fact as well as in name. In modern practice, however, a home visit is quite exceptional and is paid only to the severely disabled or seriously ill when other recourses are ruled out. All patients are normally required to go to the doctor.

It has also become unusual for a personal doctor to be available during weekends or holidays. His place may be taken by one of his partners in a group practice, a provision that is reasonably satisfactory. General practitioners, however, may now use one of several commercial deputizing services that employs young doctors to be on call. Although some of these young doctors may be well experienced, patients do not generally appreciate this kind of arrangement.

Whereas in Britain the doctor of first contact is regularly a general practitioner, in the United States the nature of first-contact care is less consistent. General practice in the United States has been in a state of decline in the second half of the 20th century, especially in metropolitan areas. The general practitioner, however, is being replaced to some degree by the growing field of family practice. In 1969 family practice was recognized as a medical specialty after the American Academy of General Practice (now the American Academy of Family Physicians) and the American Medical Association created the American Board of General (now Family) Practice. Since that time the field has become one of the larger medical specialties in the United States. The family physicians were the first group of medical specialists in the United States for whom recertification was required.

There is no national health service, as such, in the United States. Most physicians in the country have traditionally been in some form of private practice, whether seeing patients in their own offices, clinics, medical centres, or another type of facility and regardless of the patients income. Doctors are usually compensated by such state and federally supported agencies as Medicaid (for treating the poor) and Medicare (for treating the elderly); not all doctors, however, accept poor patients. There are also some state-supported clinics and hospitals where the poor and elderly may receive free or low-cost treatment, and some doctors devote a small percentage of their time to treatment of the indigent. Veterans may receive free treatment at Veterans Administration hospitals, and the federal government through its Indian Health Service provides medical services to American Indians and Alaskan natives, sometimes using trained auxiliaries for first-contact care.

In the rural United States first-contact care is likely to come from a generalist. The middle- and upper-income groups living in urban areas, however, have access to a larger number of primary medical care options. Children are often taken to pediatricians, who may oversee the childs health needs until adulthood. Adults frequently make their initial contact with an internist, whose field is mainly that of medical (as opposed to surgical) illnesses; the internist often becomes the family physician. Other adults choose to go directly to physicians with narrower specialties, including dermatologists, allergists, gynecologists, orthopedists, and ophthalmologists.

Patients in the United States may also choose to be treated by doctors of osteopathy. These doctors are fully qualified, but they make up only a small percentage of the countrys physicians. They may also branch off into specialties, but general practice is much more common in their group than among M.D.s.

It used to be more common in the United States for physicians providing primary care to work independently, providing their own equipment and paying their own ancillary staff. In smaller cities they mostly had full hospital privileges, but in larger cities these privileges were more likely to be restricted. Physicians, often sharing the same specialties, are increasingly entering into group associations, where the expenses of office space, staff, and equipment may be shared; such associations may work out of suites of offices, clinics, or medical centres. The increasing competition and risks of private practice have caused many physicians to join Health Maintenance Organizations (HMOs), which provide comprehensive medical care and hospital care on a prepaid basis. The cost savings to patients are considerable, but they must use only the HMO doctors and facilities. HMOs stress preventive medicine and out-patient treatment as opposed to hospitalization as a means of reducing costs, a policy that has caused an increased number of empty hospital beds in the United States.

While the number of doctors per 100,000 population in the United States has been steadily increasing, there has been a trend among physicians toward the use of trained medical personnel to handle some of the basic services normally performed by the doctor. So-called physician extender services are commonly divided into nurse practitioners and physicians assistants, both of whom provide similar ancillary services for the general practitioner or specialist. Such personnel do not replace the doctor. Almost all American physicians have systems for taking each others calls when they become unavailable. House calls in the United States, as in Britain, have become exceedingly rare.

In Russia general practitioners are prevalent in the thinly populated rural areas. Pediatricians deal with children up to about age 15. Internists look after the medical ills of adults, and occupational physicians deal with the workers, sharing care with internists.

Teams of physicians with experience in varying specialties work from polyclinics or outpatient units, where many types of diseases are treated. Small towns usually have one polyclinic to serve all purposes. Large cities commonly have separate polyclinics for children and adults, as well as clinics with specializations such as womens health care, mental illnesses, and sexually transmitted diseases. Polyclinics usually have X-ray apparatus and facilities for examination of tissue specimens, facilities associated with the departments of the district hospital. Beginning in the late 1970s was a trend toward the development of more large, multipurpose treatment centres, first-aid hospitals, and specialized medicine and health care centres.

Home visits have traditionally been common, and much of the physicians time is spent in performing routine checkups for preventive purposes. Some patients in sparsely populated rural areas may be seen first by feldshers (auxiliary health workers), nurses, or midwives who work under the supervision of a polyclinic or hospital physician. The feldsher was once a lower-grade physician in the army or peasant communities, but feldshers are now regarded as paramedical workers.

In Japan, with less rigid legal restriction of the sale of pharmaceuticals than in the West, there was formerly a strong tradition of self-medication and self-treatment. This was modified in 1961 by the institution of health insurance programs that covered a large proportion of the population; there was then a great increase in visits to the outpatient clinics of hospitals and to private clinics and individual physicians.

When Japan shifted from traditional Chinese medicine with the adoption of Western medical practices in the 1870s, Germany became the chief model. As a result of German influence and of their own traditions, Japanese physicians tended to prefer professorial status and scholarly research opportunities at the universities or positions in the national or prefectural hospitals to private practice. There were some pioneering physicians, however, who brought medical care to the ordinary people.

Physicians in Japan have tended to cluster in the urban areas. The Medical Service Law of 1963 was amended to empower the Ministry of Health and Welfare to control the planning and distribution of future public and nonprofit medical facilities, partly to redress the urban-rural imbalance. Meanwhile, mobile services were expanded.

The influx of patients into hospitals and private clinics after the passage of the national health insurance acts of 1961 had, as one effect, a severe reduction in the amount of time available for any one patient. Perhaps in reaction to this situation, there has been a modest resurgence in the popularity of traditional Chinese medicine, with its leisurely interview, its dependence on herbal and other natural medicines, and its other traditional diagnostic and therapeutic practices. The rapid aging of the Japanese population as a result of the sharply decreasing death rate and birth rate has created an urgent need for expanded health care services for the elderly. There has also been an increasing need for centres to treat health problems resulting from environmental causes.

On the continent of Europe there are great differences both within single countries and between countries in the kinds of first-contact medical care. General practice, while declining in Europe as elsewhere, is still rather common even in some large cities, as well as in remote country areas.

In The Netherlands, departments of general practice are administered by general practitioners in all the medical schoolsan exceptional state of affairsand general practice flourishes. In the larger cities of Denmark, general practice on an individual basis is usual and popular, because the physician works only during office hours. In addition, there is a duty doctor service for nights and weekends. In the cities of Sweden, primary care is given by specialists. In the remote regions of northern Sweden, district doctors act as general practitioners to patients spread over huge areas; the district doctors delegate much of their home visiting to nurses.

In France there are still general practitioners, but their number is declining. Many medical practitioners advertise themselves directly to the public as specialists in internal medicine, ophthalmologists, gynecologists, and other kinds of specialists. Even when patients have a general practitioner, they may still go directly to a specialist. Attempts to stem the decline in general practice are being made by the development of group practice and of small rural hospitals equipped to deal with less serious illnesses, where general practitioners can look after their patients.

Although Israel has a high ratio of physicians to population, there is a shortage of general practitioners, and only in rural areas is general practice common. In the towns many people go directly to pediatricians, gynecologists, and other specialists, but there has been a reaction against this direct access to the specialist. More general practitioners have been trained, and the Israel Medical Association has recommended that no patient should be referred to a specialist except by the family physician or on instructions given by the family nurse. At Tel Aviv University there is a department of family medicine. In some newly developing areas, where the doctor shortage is greatest, there are medical centres at which all patients are initially interviewed by a nurse. The nurse may deal with many minor ailments, thus freeing the physician to treat the more seriously ill.

Nearly half the medical doctors in Australia are general practitionersa far higher proportion than in most other advanced countriesthough, as elsewhere, their numbers are declining. They tend to do far more for their patients than in Britain, many performing such operations as removal of the appendix, gallbladder, or uterus, operations that elsewhere would be carried out by a specialist surgeon. Group practices are common.

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medicine | Definition, Fields, Research, & Facts …

My Medicine – WebMD

WebMD My Medicine Help

Q: What is an interaction?

A: Mixing certain medicines together may cause a bad reaction. This is called an interaction. For example, one medicine may cause side effects that create problems with other medicines. Or one medicine may make another medicine stronger or weaker.

Q: How do you classify the seriousness of an interaction?

A: The following classification is used:

Contraindicated: Never use this combination of drugs because of high risk for dangerous interaction

Serious: Potential for serious interaction; regular monitoring by your doctor required or alternate medication may be needed

Significant: Potential for significant interaction (monitoring by your doctor is likely required)

Mild: Interaction is unlikely, minor, or nonsignificant

Q: What should I do if my medications show interactions?

A: Call your doctor or pharmacist if you are concerned about an interaction. Do not stop taking any prescribed medication without your doctor’s approval. Sometimes the risk of not taking the medication outweighs the risk or the interaction.

Q: Why can’t I enter my medication?

A: There may be medications, especially otc or supplements, that have not been adequately studied for interactions. If we do not have interaction information for a certain medication it can’t be saved in My Medicine.

Q: Do you cover all FDA warnings?

A: WebMD will alert users to the most important FDA warnings and alerts affecting consumers such as recalls, label changes and investigations. Not all FDA actions are included. Go to the FDA for a comprehensive list of warnings.

Q: Can I be alerted by email if there is an FDA warning or alert?

A: Yes. If you are signed in to WebMD.com and using My Medicine you can sign up to receive email alerts when you add a medicine. To unsubscribe click here.

Q: Can I add medicines for family members?

A: Yes. Click the arrow next to your picture to add drug profiles for family or loved ones.

Q: Can I access My Medicine from my mobile phone?

A: Yes. Sign in to the WebMD Mobile App. Your saved medicine can be found under “Saved.”

Q: Why are there already medicines saved when this my first time using this tool?

A: If you have previously saved a medication on WebMD, for example, in the WebMD Mobile App, these may display in My Medicine.

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My Medicine – WebMD

Elon Musk: $47,000 Model Y SUV “Will Ride Like a Sports Car”

A Familiar Car

First, it was supposed to feature Model-X-style “falcon wing” doors, and then it didn’t. It was supposed to be built in the Shanghai factory, but that didn’t work out either.

Tesla finally unveiled its fifth production car, the Model Y, at its design studio outside of Los Angeles Thursday evening.

“It has the functionality of an SUV, but it will ride like a sports car,” Tesla CEO Elon Musk said during the event. “So this thing will be really tight on corners.”

Bigger than the 3, Smaller Than the X

Yes, acceleration is still zippy: zero to 60 in 3.5 seconds.

But the vehicle is less than revolutionary. It’s arguably the company’s second crossover sports utility vehicle, after the Model X, and it borrows heavily from the company’s successful Model 3. In fact, 75 percent of its parts are the same, according to CEO Elon Musk.

The back of the Y is slightly elevated in the back for a roomier cargo space. A long-range model will feature seven seats — just like the Model X, despite being slightly smaller. Range: still 300 miles with the Long Range battery pack, thanks to its aerodynamic shape.

It will also be “feature complete” according to Musk, referring to the fact that the Model Y will one day be capable of “full self-driving” that he says “will be able to do basically anything just with software upgrades.”

10 Percent Cheaper

As expected, the Model Y is ten percent bigger and costs roughly ten percent more than the Model 3: the first Model Y — the Long Range model — will be released in the fall of 2020 and will sell for $47,000. A dual-motor all-wheel drive version and a performance version will sell for $51,000 and $60,000, respectively.

If you want to save a buck and get the ten-percent-cheaper-than-the-Model-3 version, you’ll have to wait: a Standard Range (230 miles) model will go on sale in 2021 for just $39,000.

Overall, the Model Y seems like a compromise: it’s not a radical shift, but it seems carefully designed to land with a certain type of consumer — and, if Musk is to be believed, without sacrificing Tesla’s carefully-cultivated “cool factor.”

Investors seemed slightly underwhelmed, too — the company’s stock reportedly slid up to five percent after the announcement.

READ MORE:  Tesla unveils Model Y electric SUV with 300 miles range and 7-seats [Electrek]

More on the Model Y: Elon Musk: Tesla Will Unveil Model Y Next Week

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Elon Musk: $47,000 Model Y SUV “Will Ride Like a Sports Car”

Special Announcement: Futurism Media and Singularity University

Futurism acquired by Singularity University

So, Readers –

As always, we’ve got some news about the future. Except this time, it’s about us.

We’re about to enter the next chapter of Futurism, one that will usher in a new era for this site. It’ll come with new ways we’ll be able to deliver on everything you’ve grown to read, watch, subscribe to, and love about what we do here. And also, more in volume of what we do, with larger ambitions, and ultimately, a higher level of quality with which we’re able to bring those ambitions to fruition.

As of today, Futurism Media is proud to announce that we’re joining operations with Singularity University. In other words: They bought us, they own us, and quite frankly, we’re excited about the deal.

It’s an excitement and an occasion we share in with you, our community of readers — aspiring and working technologists, scientists, engineers, academics, and fans, who carried us to where we are, who helped make this independent media company what it is today. We’ve always been humbled by your support, and we’ve worked to reciprocate it by publishing one of the most crucial independent technology and science digital digests, every day, full stop.

What this changes for you? Nothing. Really. Except: More of what you’ve come to count on Futurism.com to deliver every time you’ve read our stories, opened our emails, swiped up on our ‘Gram, watched our videos, dropped in on our events, clicked through a Byte, and so on. This partnership represents the sum total of the work you’ve engaged with, and the start of a new chapter in which we’ll be able to deliver on more of the above.

That means increased coverage of the emergent, cutting-edge innovation and scientific developments changing the world, and the key characters and narratives shaping them (or being shaped by them). It means an expanded, in-depth feature publishing program, arriving this Spring (it’s rad, and it’s gonna blow your socks off). It means more breaking news reporting and analysis. It means original media products you haven’t seen from us before — new verticals, microsites, other ways for you to get in the mix with our coverage. And yes, by working in concert with Singularity University, we’re going to have a pretty decent competitive advantage: Direct access to the characters and personas shaping our future, the people, ideas, and innovations right at the frontier of exponential growth technologies. Our branded content team, Futurism Creative, will also continue to produce guideline-abiding, cutting-edge, thoughtful and engaging content for our partners, and for the partners of SU, too. And finally, our Futurism Studios division will continue to push the envelope of feature-length narrative storytelling of the science fiction (and science fact) stories of that future.

Will this change our journalism? Not in the slightest. We’ll still be operating as an independent, objective news outlet, without interference from our partners, who will continue to hold us to the same ethics and accountability standards we’ve held ourselves to these last few years. There might be more appearances from the folks at SU in our work (not that SU’s proliferate network of notable alumni or board members haven’t previously made appearances around these parts prior to this), but by no means will SU be shoehorning themselves into what we do here.

Yet: Where the opportunity exists, we’ll absolutely seize on the chance to co-create and catalyze action together to shape the technology and science stories on the horizon, to say nothing of that future itself. We’ll continue to make quality the primary concern — and they’re here to support that mandate, and augment this team with additional resources to accomplish it. If even the appearance of a conflict presents itself, as always, we’ll default to disclosure. But it’d be absurd of us not to take advantage of the immense base of knowledge our new partners in Mountain View have on offer (an apt comparison here would be, say, Harvard Business Review to H.B.S. or M.I.T. and our contemporaries at the MIT Technology Review).

We’ve been circling this partnership for a while; they, fans of ours, and us, fans of theirs. The original mandate of Futurism as written by our C.E.O. Alex Klokus was to increase the rate of human adaptability towards the future through delivering on the news of where that future is headed. Singularity University concerns itself with educating the world on the exponential growth technologies changing our lives. It’s a perfect merging of interests. Where exponential growth technologies are concerned: One only need look as far as the way online advertising and social platforms changed the economics of media to see this. To find a home with a growing institution that will prove increasingly vital to the growing global community they’ve already established in spades is the best possible outcome. And no, we didn’t get crazy-rich or anything. But we did galvanize the future (and all its possibilities) for everyone at this company, and our ability to keep serving you, our readers.

We’re immensely proud of the scrappy, tight team here; and especially you, our community of readers and partners we’ve grown with these last few years. We’re proud of the product we’ve created, especially last year, when we steered away from reliance on social media platforms for an audience, and reconfigured an editorial strategy around the priority of driving you directly to Futurism.com daily, by prioritizing quality, topicality, reliability, and on-site presentation (shocker: it worked). Now, we proud to be able to do more, better, of what we’ve always done here:

Tell the stories of tomorrow, today. On behalf of the entire Brooklyn-based Futurism team, thanks for being along for the ride so far, and on behalf of the new Futurism x Singularity University family, here’s to more of where that came from.

The future, as ever, is looking bright. We can’t wait to tell you about it.

– Foster Kamer
Director of Content

James Del
Publisher

Sarah Marquart
Director of Strategic Operations

Geoff Clark
President of Futurism Studios

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Special Announcement: Futurism Media and Singularity University

Just 19 Percent of Americans Trust Self-Driving Cars With Kids

A new survey by AAA shows that most Americans distrust self-driving cars. In the past two years, public trust in the emerging technology has gone down.

Poor Turnout

While tech companies like Waymo, Uber, and Tesla race to be the first to build a fully-autonomous vehicle, the public is left eating their dust.

About 71 percent of Americans say that they don’t trust self-driving cars, according to a new American Automobile Association (AAA) survey. That’s roughly the same percentage as last year’s survey, but it’s eight points higher than in 2017, according to Bloomberg and just 19 percent say they’d put their children or family members into an autonomous vehicle.

Overall, the data is a striking sign of public fatigue with self-driving cars.

Track Record

Autonomous vehicles, unlike some other emerging technologies, have suffered very public setbacks, including when an Uber vehicle struck and killed a pedestrian a year ago.

“It’s possible that the sustained level of fear is rooted in a heightened focus, whether good or bad, on incidents involving these types of vehicles,” said AAA director of automotive engineering Greg Brannon in a statement obtained by Bloomberg. “Also it could simply be due to a fear of the unknown.”

Uphill Battle

The AAA survey found that Americans are more accepting of autonomous vehicle tech in limited-use cases. For example, 53 percent of survey respondents were okay with self-driving trams or shuttles being used in areas like theme parks, while 44 percent accepted the idea of autonomous food-delivery bots.

Self-driving car companies are currently engaging in public relations efforts to earn people’s trust, Bloomberg reports. But if these AAA numbers are any indication, there’s a long way to go.

READ MORE: Americans Still Fear Self-Driving Cars [Bloomberg]

More on autonomous vehicles: Exclusive: A Waymo One Rider’s Experiences Highlight Autonomous Rideshare’s Shortcomings

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Just 19 Percent of Americans Trust Self-Driving Cars With Kids

This Guy Spent a Whole Week In a VR Headset

Jak Wilmot, co-founder of Disrupt VR, an Atlanta-based VR content studio, spent 168 consecutive hours in a VR headset, locked up in his apartment.

The Dumbest Thing

Jak Wilmot, the co-founder of Atlanta-based VR content studioDisrupt VR, spent 168 consecutive hours in a VR headset — that’s a full week — pent up in his apartment.

“This is quite possibly the dumbest thing I’ve ever done, but welcome to a week in the future,” he said in a video about the experiment.

To make the experience even more futuristic, Wilmot livestreamed the entire week on Twitch late last month, later uploading a wrapup video on his entire week on YouTube.

The rules were simple: he could switch from a computer-based Oculus headset to a different, untethered headset for thirty seconds while his eyes were closed. His windows were blacked out, he said, so that his physical body didn’t have to rely on the daylight-dependent circadian rhythm.

His more mobile VR headset had a built in camera in the front, so that he was able to “see” his physical surroundings — but not directly with his own eyes.

“Everything is in the Headset”

Wilmot worked, ate and exercised inside virtual reality. Sleeping in the headset turned out to be “more comfortable” than Wilmot anticipated, though his eyes burned a bit.

“If one is feeling stressed, they can load into a natural environment for ten minutes and relax,” he said in the video. “If one is feeling energetic, they can dispel energy in a fitness game — these are like the new rules of the reality I’ve thrown myself in. Everything is in the headset.”

VR Connection

Wilmot believes that virtual reality is what you make it. If you want to be alone, you can spend time by yourself in a gaming session, slaying dragons in Skyrim VR. Or you can chose to join the cacophony of VRChat — a communal free-for-all multiplayer online platform that allows you to interact with avatars controlled by complete strangers.

“VR is stepping into the shoes of someone else, or stepping into a spaceship and talking to friends,” said Wilmot. “It’s very easy to find your tribe, to make friends, to communicate with others through a virtual landscape, where its no longer through digital window [like a monitor], but actually being there with them. To me that’s what VR is — connection.”

Escaping Virtual Reality

After seven days of living inside the headset, Wilmot took off the goggles and relearned what it’s like to live in the real world.

Experiment_01… ????????

Subject Status… ????? pic.twitter.com/HC0Jqb3aZq

— jak (@JakWilmot) February 27, 2019

Apart from slight dizziness and some disorientation, he came back to normal almost instantly.

One major advantage to not living inside a VR headset: “oh my gosh,” he said, “the graphics are so good.”

READ MORE: This Guy Is Spending A Full Week In VR, For Science [VR Scout]

More on virtual reality: Sex Researchers: For Many, Virtual Lovers Will Replace Humans

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This Guy Spent a Whole Week In a VR Headset

How Can We Build Cities to Accommodate 6.5 Billion People?

By 2050, 6.5 billion people will choose to live in cities. These individuals will require employment and access to better healthcare from an infrastructure that is already extremely vulnerable. The Global Maker Challenge asked makers and innovators to help put forward solutions for this issue, and they delivered.

The post How Can We Build Cities to Accommodate 6.5 Billion People? appeared first on Futurism.

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How Can We Build Cities to Accommodate 6.5 Billion People?

Samsung Is Working on Phone With “Invisible” Camera Behind Screen

A Samsung exec has shared new details on the company's efforts to create a full-screen phone, one with the camera embedded beneath the display.

Punch It

Just last month, South Korean tech giant Samsung unveiled the Galaxy S10, a phone with just a single hole punched in the screen to accommodate its front-facing camera.

On Thursday, a Samsung exec shared new details on the company’s intentions to create a “perfect full-screen” phone, with an “invisible” camera behind the screen to eliminate the need for any visible holes or sensors — confirming that one of the biggest players in tech sees edge-to-edge screens as the future of mobile devices.

Hidden Tech

During a press briefing covered by Yonhap News Agency, Samsung’s Mobile Communication R&D Group Display Vice President Yang Byung-duk said the company’s goal is to create a phone with a screen that covers the entire front of the device — but consumers shouldn’t expect it in the immediate future.

“Though it wouldn’t be possible to make (a full-screen smartphone) in the next 1-2 years,” Yang said, “the technology can move forward to the point where the camera hole will be invisible, while not affecting the camera’s function in any way.”

Quest for Perfection

This isn’t Samsung’s first mention of an uninterrupted full-screen phone — as pointed out by The Verge, the company discussed its ambitions to put the front-facing camera under a future device’s screen during a presentation in October.

That presentation included a few additional details on how the camera in a full-screen phone would work.

Essentially, the entire screen would serve as a display whenever the front-facing camera wasn’t in use. When in use, however, the screen would become transparent, allowing the camera to see through so you could snap the perfect selfie — and based on Yang’s comments, that new innovation could be just a few years away.

READ MORE: Samsung Seeks Shift to Full Screen in New Smartphones [Yonhap News Agency]

More on Samsung: Samsung Just Revealed a $1,980 Folding Smartphone

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Samsung Is Working on Phone With “Invisible” Camera Behind Screen

Slack Just Removed a Bunch of Hate Groups

Workplace messaging app Slack just announced that it banned 28 accounts that were known to be affiliated with hate groups.

Violating Terms

Slack, the team collaboration app commonly used to connect people within workplaces, announced Thursday that it had deleted 28 accounts that were clearly affiliated with hate groups, according to the company’s blog.

The announcement, sparse on concrete details or specifics, states that hate groups are explicitly unwelcome on the app and that Slack will continue to investigate and act on any future reports of hate speech or illegal activity.

“Today we removed 28 accounts because of their clear affiliation with known hate groups,” the statement reads. “The use of Slack by hate groups runs counter to everything we believe in at Slack and is not welcome on our platform.”

Joining the Fight

In recent years, major platforms like Facebook and Twitter have struggled to keep white supremacists and other hate groups from spreading their messages across the internet, though both ban Nazi messaging in Germany, where Holocaust denial is illegal.

Smaller scale platforms like Discord also recently started acting against hate groups, according to The Verge, which speculates that Slack’s focus on business communications instead of cultivating largescale communities may have helped the company avoid the issue of online hatemongering.

Real World Consequences

When hate speech is allowed to propagate online, it can lead to real-world violence — like the murder of Heather Heyer at a 2017 white supremacist rally. But banning hate groups and de-platforming the people behind them, as Slack claims to have done, is a successful strategy.

When right-wing activist Milo Yiannopolous was no longer permitted by online platforms to spread his racist and misogynistic viewpoints, he found himself effectively powerless and millions of dollars in debt, according to The Guardian.

“Using Slack to encourage or incite hatred and violence against groups or individuals because of who they are is antithetical to our values and the very purpose of Slack,” the company’s statement reads. “When we are made aware of an organization using Slack for illegal, harmful, or other prohibited purposes, we will investigate and take appropriate action and we are updating our terms of service to make that more explicit.”

READ MORE: Slack says it removed dozens of accounts affiliated with hate groups [The Verge]

More on content moderation: The UK Government Is Planning to Regulate Hate Speech Online

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Slack Just Removed a Bunch of Hate Groups