Kids Research Express

Galen, the most outstanding physician of antiquity after Hippocrates. His anatomical studies on animals and observations of how the human body functions dominated medical theory and practice for 1400 years. Galen was born of Greek parents in Pergamum, Asia Minor, which was then part of the Roman Empire. A shrine to the healing god Asclepius was located in Pergamum, and there young Galen observed how the medical techniques of the time were used to treat the ill or wounded. He received his formal medical training in nearby Smyrna and then traveled widely, gaining more medical knowledge. About 161 he settled in Rome, where he became renowned for his skill as a physician, his animal dissections, and his public lectures. About 169, the Roman emperor Marcus Aurelius appointed Galen as the physician to his son Lucius Aelius Aurelius Commodus. Most of Galen's later life was probably spent in Rome. Galen dissected many animals, particularly goats, pigs, and monkeys, to demonstrate ho...

Gabriello Fallopio (1523?-1562), also known as Gabriello Fallopio and Gabriel Fallopius, Italian anatomist, physician, botanist, and surgeon. Born in Modena, Fallopio studied medicine at the University of Ferrara, and after receiving his degree he worked and studied at various European medical schools. Fallopio became professor of anatomy at Ferrara in 1548 and professor of surgery and anatomy at the University of Pisa about a year later. In 1551 Cosimo I dè Medici, grand duke of Tuscany, called him to a similar post at Pisa to succeed Andreas Vesalius, the Belgian anatomist. There he also held the chair of botany and materia medica and was superintendent of the botanical gardens. Fallopio's work dealt primarily with cranial anatomy and he added considerably to the knowledge of the ear. He was the first to use the ear speculum instrument to diagnose diseases of the ear and the first to show the connection between the mastoid, a part of the skull that houses the ear, and the mi...

Forestry is the art and science of managing forests, tree plantations , and related natural resources. The main goal of forestry is to create and implement systems that allow forests to continue a sustainable continuation of environmental supplies and services. The challenge of forestry is to create systems that are socially accepted while sustaining the resource and any other resources that might be affected. Silviculture, a related science, involves the growing and tending of trees and forests. Modern forestry generally embraces a broad range of concerns, including assisting forests to provide timber as raw material for wood products, wildlife habitat, natural water quality management, recreation, landscape and community protection, employment, aesthetically appealing landscapes , biodiversity management, watershed management, erosion control , and preserving forests as 'sinks' for atmospheric carbon dioxide. A practitioner of forestry is known as a forester. Forest...

Lorentz contraction (lôr`ĕnts), in physics, contraction or foreshortening of a moving body in the direction of its motion, proposed by H. A. Lorentz on theoretical grounds and based on an earlier suggestion by G. F. Fitzgerald; it is sometimes called the Fitzgerald, or Lorentz-Fitzgerald, contraction. The Lorentz contraction hypothesis was put forward in an attempt to explain the negative result of the Michelson-Morley experiment of 1887 designed to demonstrate the earth's absolute motion through space (see  ether ;  relativity ). The hypothesis held that any material body is contracted in the direction of its motion by a factor 1− v 2 / c 2 , where  v  is the velocity of the body and  c  is the velocity of light. Although the Lorentz contraction did not succeed entirely in reconciling the results of the Michelson-Morley experiment with classical theory, it did serve as the basis for the mathematics of Einstein's theory of relativity. The equations used in ...

Atomic clock, electric or electronic timekeeping device that is controlled by atomic or molecular oscillations. A timekeeping device must contain or be connected to some apparatus that oscillates at a uniform rate to control the rate of movement of its hands or the rate of change of its digits. Mechanical clocks and watches use oscillating balance wheels, pendulums, and tuning forks. Much greater accuracy can be attained by using the oscillations of atoms or molecules. Because the frequency of such oscillations is so high, it is not possible to use them as a direct means of controlling a clock. Instead, the clock is controlled by a highly stable crystal oscillator whose output is automatically multiplied and compared with the frequency of the atomic system. Errors in the oscillator frequency are then automatically corrected. Time is usually displayed by an atomic clock with digital or other sophisticated readout devices. The first atomic clock, invented in 1948, utilized the vibration...

Astronomy was revolutionized in the second half of the 19th cent. by the introduction of techniques based on photography and spectroscopy. Interest shifted from determining the positions and distances of stars to studying their physical composition (see stellar structure and stellar evolution ). The dark lines in the solar spectrum that had been observed by W. H. Wollaston and Joseph von Fraunhofer were interpreted in an elementary fashion by G. R. Kirchhoff on the basis of classical physics, although a complete explanation came only with the quantum theory . Between 1911 and 1913, Ejnar Hertzsprung and H. N. Russell studied the relation between the colors and luminosities of typical stars (see Hertzsprung-Russell diagram ). With the construction of ever more powerful telescopes (see observatory) , the boundaries of the known universe constantly increased. E. P. Hubble's study of the distant galaxies led him to conclude that the universe is expanding (see Hubble's law ). Usin...

The Copernican Revolution After the fall of Rome, European astronomy was largely dormant, but significant work was carried out by the Muslims and the Hindus. It was by way of Arabic translations that Greek astronomy reached medieval Europe. One of the great landmarks of the revival of learning in Europe was the publication (1543) by Nicolaus Copernicus (1473–1543) of his De revolutionibus orbium coelestium (On the Revolutions of the Celestial Spheres). According to the Copernican system , the earth rotates on its axis and, with all the other planets, revolves around the sun. The assertion that the earth is not the center of the universe was to have profound philosophical and religious consequences. Copernicus's principal claim for his new system was that it made calculations easier. He retained the uniform circular motion of the Ptolemaic system, but by placing the sun at the center, he was able to reduce the number of epicycles. Copernicus also determined the sidereal periods (t...