- 行业: Printing & publishing
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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.
El Niño is a warming of the tropical Pacific Ocean that occurs roughly every 3 to 7 years. It develops in association with swings in atmospheric pressure known as the Southern Oscillation. During El Niño, the tradewinds weaken along the Equator as atmospheric pressure rises in the western Pacific and falls in the eastern Pacific. This condition allows warm water, normally confined to the far western Pacific, to migrate eastward. Upwelling, a process which brings nutrient-rich cold water to the surface along the coast of South America and along the Equator, is shut down, and sea surface temperatures warm in the central and eastern Pacific. Deep cumulus clouds and heavy rains, normally occurring in the western Pacific over the warmest water, migrate eastward in response to these surface temperature changes. These changes leave the western Pacific dry but bring torrential rains to the islands of the central Pacific and the west coast of South America.
Industry:Science
Electronic circuits for locking an oscillator in phase with an arbitrary input signal. A phase-locked loop (PLL) is used in three fundamentally different ways: (1) as a demodulator, where it is employed to follow (and demodulate) frequency or phase modulation; (2) as a tracker of a carrier or synchronizing signal which may vary in frequency with time; and (3) as a frequency synthesizer, where an oscillator is locked to a multiple of an accurate reference frequency. When operating as a demodulator, the phase-locked loop may be thought of as a matched filter operating as a coherent detector. When used to track a carrier, it may be thought of as a narrow-band filter for removing noise from the signal and regenerating a clean replica of the signal. When used as a frequency synthesizer, a voltage-controlled oscillator (VCO) is divided down to a reference frequency that is locked to a frequency derived from an accurate source such as a crystal oscillator.
Industry:Science
DARPP-32 is a master molecular regulator in neurons that receive the neurotransmitter dopamine. For over two decades, an intense research effort has demonstrated that DARPP-32 occupies a unique position as a central molecular control point, integrating multiple information streams that converge through a variety of neurotransmitters, neuromodulators, neuropeptides, and steroid hormones onto dopaminoceptive neurons. Since dopaminergic neurotransmission is critical for motivated behavior, working memory, and reward-related learning and is implicated in, among other conditions, schizophrenia, alcoholism, Parkinson's disease, and pathological gambling, DARPP-32 has received considerable attention not only in basic neuroscience, but also in studies of the pathogenesis of these disorders and as a promising target for innovative drug treatment in psychiatry. In addition, DARPP-32 is found in nonneuronal tissues and may have relevance for certain types of cancer.
Industry:Science
Fungi which usually produce neither sexual (meiotic) nor asexual (mitotic) spores. These fungi have been denoted by various names. The most common names are Mycelia Sterilia (having sterile mycelium), Agonomycetales (used when classifying these fungi at the level of order), or Agonomycetes (used when assigning their rank at the level of class). These fungi make up an artificial (nonphylogenetic) group consisting of both ascomycetes and basidiomycetes. A few species have associated sexual states, but these sexual states are infrequently produced. Although true spores are mostly lacking in this group, some species produce sporelike structures which function effectively in survival and dispersal of the species. Some of these sporelike structures mimic true spores so well in form and function that the genera producing them (for example, <i>Beverwykella</i>, <i>Cancellidium</i>, and <i>Tretopileus</i>) have occasionally been classified with spore-forming fungi.
Industry:Science
Construction of new nuclear power plants is expected to restart shortly in the United States, and the number of nuclear plants worldwide is expected to jump beyond the 435 current plants producing 15% of the world's electricity. Most nuclear plants use nuclear fission of fissionable uranium-235 to produce large amounts of energy due to mass conversion into energy. That heat generation is removed by coolants which go on to produce electricity. The fissions generate fission products (FP) and neutrons absorbed into fertile uranium-238 to produce plutonium (Pu) and minor actinides (MA), consisting of americium (Am), curium (Cm), and neptunium (Np). There are two principal types of reactors: thermal and fast. Thermal reactors use a moderator to reduce their energy level, while fast reactors with no moderator operate at a much higher energy level and can better fission plutonium and minor actinides. Also, they produce more neutrons and can breed fissile material.
Industry:Science
Earthquakes occur when the friction that prevents a fault from slipping is overcome by the gradual accumulation of stress acting across the fault and starts the material on the two sides of the fault slipping past each other. As slip occurs, frictional resistance drops, and the resulting rapid and unstable slip generates seismic waves that radiate outward in all directions from the initiation point, or hypocenter. These seismic waves are recorded by seismographs deployed on the Earth's surface, and their arrival times are the information that is used to determine the hypocenter. The distribution of earthquake hypocenters is one of the principal tools that seismologists use to understand earthquake behavior. Thus, it is important to minimize the uncertainties in determining earthquake hypocenters. Because networks of seismographs are set up to locate and catalog earthquakes automatically, refinement of earthquake locations is often referred to as relocation.
Industry:Science
Analysis of the geothermal gradient near the surface of the Earth is extending knowledge of land surface temperatures hundreds of years into the past before the advent of the instrumental meteorological record. Vertical temperature versus depth profiles of the upper crust (down to 600 m; 2000 ft) contain a recoverable record of surface temperature change over the past few centuries due to particular thermophysical properties of the continental crust, low thermal diffusivity, and a steady-state surface heat flux from the interior. This new method of climate change research provides a direct record of past temperatures, unlike proxy data such as tree rings, paleobotany, stable isotopes, and lake salinity, which rely on analogy or transfer functions. Continued data collection and analysis on all continental areas has the potential to yield a global temperature record that may enable scientists to understand different forcing mechanisms in global climate change.
Industry:Science
Diesel engines remain the dominant means of ship propulsion. In recent years, they have shown continuing progress in areas of refined manufacturing, higher power output per unit of engine volume (power density) and per unit weight, reduced fuel and lubricating oil consumption, improved tolerance for fuels of low quality, simplified maintenance requirements, suppression of vibration, application of electronic monitoring and control, and reduction of exhaust emissions. There have been promising developments in the use of natural gas as a marine fuel. There has been a dramatic consolidation in the diesel-engine manufacturing industry, resulting from the increasing sophistication (and cost) of the research, design processes, prototype testing, manufacturing methods, and after-service sales obligations that have become part of the manufacturing process, leaving fewer engine designs of increasing similarity to be built worldwide by closely cooperating manufacturers.
Industry:Science
Extensive research in humans and animals has established that exercise has beneficial effects on general health as well as on the health and functioning of the brain. For example, the benefits of exercise on cardiovascular health, obesity, diabetes, and cancer progression have been well described. Moreover, recent research has elucidated aspects of cognitive health and function that are improved by exercise, as well as mechanisms that might be mediating these cognitive benefits. In humans, the greatest benefits of exercise on cognitive function have been demonstrated in aged populations, in part because much human research focuses on interventions to counteract the normal cognitive decline that is associated with aging. The breadth of human exercise studies has expanded in recent years, revealing that beneficial effects of exercise on the brain extend across the life span, from the aged to young adults, adolescents, and children, and even to prenatal development.
Industry:Science
Foods are physicochemical systems in which a number of phases and chemical compounds can coexist in a metastable condition (that is, far from true thermodynamic equilibrium), and in the presence of microbes, whose metabolism may cause significant modifications of the chemical composition and physical properties of the hosting product. For this reason, food science not only deals with protection from external chemical, physical, and microbial injuries (for example, through the use of suitable additives or packaging), but also investigates the intrinsic causes of food instability, such as phase separations of dispersed systems, phase transitions (which mainly concern food polymers, such as starch, gluten and other proteins, and fats), enzymatic reactions (often related to the “endogenous” microbial agents), and preparation procedures (such as cooking, extruding, and freezing), all of which can profoundly modify the nutritional and sensory properties of the product.
Industry:Science
