- 行业: Printing & publishing
- Number of terms: 178089
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- Company Profile:
McGraw Hill Financial, Inc. is an American publicly traded corporation headquartered in Rockefeller Center in New York City. Its primary areas of business are financial, publishing, and business services.
The four cardinal signs of inflammation of tissues are swelling, redness, pain, and heat. Inflammation is caused by a complex network of mediators, receptors, and white blood cells that interact with the vasculature and nerve fibers. In recognizing inflammation histologically, the swelling and redness come from localized edema secondary to enhanced vascular permeability in the postcapillary venules and tissue infiltration by leukocytes. When the leukocytes are predominantly polymorphonuclear neutrophils, the process is usually acute. In chronic inflammation, in contrast, the infiltrating cells are lymphocytes and mononuclear phagocytes. The answer as to why inflammatory response exists lies in the nature of innate and acquired immunity, and the complex response of multicellular organisms to threats from the environment.
Industry:Science
The ejection of electrons from a solid (or less commonly, a liquid) by incident electromagnetic radiation. Photoemission is also referred to as the external photoelectric effect. The visible and ultraviolet regions of the electromagnetic spectrum are most often involved, although the infrared and x-ray regions are also of interest. Photoemission has several distinguishing experimental features: (1) the process of photon absorption and photoelectron generation is instantaneous, that is, there is no detectable time lag; (2) at a given frequency the number of photoelectrons ejected per second is proportional to the intensity of the incident radiation; and (3) the kinetic energies of the photoelectrons depend on the incident photon frequency and the work function of the surface, but are independent of the incident intensity.
Industry:Science
The clade that includes all living and extinct species that share a closer relationship with modern mammals than with modern reptiles. The evolutionary history of synapsids is usually described in terms of three major radiations. The oldest synapsids are Middle Pennsylvanian in age (approximately 320 million years ago (Ma)) and belong to the earliest, “pelycosaur” radiation. Pelycosaur-grade synapsids are known primarily from Texas, Oklahoma, and surrounding states, although several fossils have been discovered in Europe. By the Middle Permian (260 Ma), a group of advanced synapsids, the therapsids, had achieved nearly complete distribution across the supercontinent of Pangea. As with their pelycosaur forebears, therapsids diversified into both carnivorous and herbivorous species, some growing up to 3–4 m (10–13 ft) in length.
Industry:Science
Steel is produced in many forms, and its composition varies greatly from one application to the next. Structural steel is the common name for the material that is used for buildings, bridges, and structures in general. With properties that allow it to withstand the effects of high winds, earthquakes, and other types of loads, it has been the construction material for a very large number of structures since 1874. That was the year of completion of the Eads Bridge in St. Louis, Missouri, recognized worldwide as the first application of what is called structural steel today. Since then, the number and types of projects where steel has been the key material has increased exponentially, including such historical examples as the Eiffel Tower in Paris, the Empire State Building in New York, and the Golden Gate Bridge in San Francisco.
Industry:Science
The branch of geology that deals with the ways in which geology affects people. Examples of the effect of geology on human civilizations include (1) the ways that fertile soils develop from rocks and how these soils can become polluted by human activities; (2) how rocks and soils move down-slope to destroy roads, houses, and other human constructions; (3) sources of surface and subsurface water supplies and how they become polluted; (4) why floods occur where they do and how human activities affect floods; (5) locations of earthquakes and volcanic eruptions and the dangers they pose; (6) location of mineral resources such as copper, oil and gas, and uranium, and how mining these resources can pollute the environment; (7) how human activities can pollute the atmosphere and cause global warming, sea-level rise, and ozone depletion.
Industry:Science
The addition of deoxyribonucleic acid (DNA) to living cells, thereby changing their genetic composition and properties. Such transformation was first reported by Fred Griffith in 1928 as occurring in pneumonia bacteria (pneumococci, or <i>Streptococcus pneumoniae</i>) growing in animals injected in the laboratory. Other investigators produced the same phenomenon in bacteria of the same species growing in the test tube. The process is looked upon as the transfer of a transforming principle, or substance, from donor bacteria to suitable recipient bacteria. The recipient bacteria are usually closely related to the donor strain. It is realized that the process may occur in natural conditions, for example, in a host animal infected with two parasitic strains, and indeed it might play a part in the rapid evolution of pathogenic bacteria.
Industry:Science
Tallgrass prairie is one of the most diverse and productive types of grassland in North America. Historically, tallgrass prairie stretched from Canada to Texas and from Kansas to Ohio. West of the tallgrass prairie lie drier, less productive grasslands, and to the east are deciduous forests. Throughout the presettlement range of this grassland, tallgrass prairie was characterized by three interacting forces: a variable climate that on average provided sufficient precipitation to support forest but was prone to drought; frequent fire that promoted grass growth but suppressed woody species; and grazing by large ungulate herbivores (bison). Today, tallgrass prairie is termed America's most endangered ecosystem because more than 95% of the original prairie has been lost to row crop agriculture, and what remains has been highly fragmented.
Industry:Science
The detection and recording of electrical activity generated by muscle fibers. The basic elements of motor control in the body are the motor units which comprise motor neurons in the brainstem or spinal cord, their axons, and from ten to several hundred muscle fibers supplied by each motor neuron. Motor units vary in the size and properties of their motoneurons, the sizes and conduction velocities of their axons, the morphology of their nerve muscle junctions, and the structure and physiological properties of the muscle fibers supplied by each motor neuron. Voluntary activity recruits motor units in an orderly manner, beginning with smaller, twitch units with more slowly conducting axons recruited in weak contractions and progressing to much-harder-to-recruit, larger and faster-twitch motor units with more rapidly conducting axons.
Industry:Science
The continent of Australia is home to many exotic mammals, including hopping kangaroos, egg-laying platypus, spiky echidnas, carnivorous Tasmanian devils, and cuddly koalas. The ancestors of these present-day Australian mammals lived on the Gondwana supercontinent (the ancient landmass that later fragmented and drifted apart to eventually form the present continents). Splitting of the Gondwana landmass, starting about 145–200 million years ago, separated mammals in Australia from mammals in Africa, South America, India, and Antarctica. Vast oceans between the modern continents created geographical barriers, allowing the independent evolution of the unique mammalian fauna of Australia. It is possible to trace these historical events and understand the relationship of animals with the use of the molecule common to all living things: DNA.
Industry:Science
The force exerted on a body whenever there is a relative velocity between the body and the air. There are only two basic sources of aerodynamic force: the pressure distribution and the frictional shear stress distribution exerted by the airflow on the body surface. The pressure exerted by the air at a point on the surface acts perpendicular to the surface at that point; and the shear stress, which is due to the frictional action of the air rubbing against the surface, acts tangentially to the surface at that point. The pressure and shear stress act at each point on the body surface, and hence the distribution of pressure and shear stress represent a distributed load over the surface. The net aerodynamic force on the body is due to the net imbalance between these distributed loads as they are summed (integrated) over the entire surface.
Industry:Science
