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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.
Diabetes mellitus is a metabolic disorder that is characterized primarily by chronic hyperglycemia (excessive sugar (glucose) in the blood) resulting from defects in insulin secretion, insulin action, or both. The symptoms of hyperglycemia include those caused by osmotic diuresis (increased urination because of the presence of certain substances, such as glucose, in the kidney tubules) and the resultant loss of calories (including polyuria (passage of copious amounts of urine), polydipsia (excessive thirst), weight loss, and polyphagia (excessive eating)); blurring of vision caused by fluctuations in the diameter of the ocular lens; and increased susceptibility to infections, particularly urinary tract infections and skin infections.
Severe life-threatening acute metabolic complications include diabetic ketoacidosis (excessive amounts of acidic ketones in the blood) and hyperosmolar nonketotic state (a dangerous condition caused by very high levels of blood sugar and dehydration). Chronic effects of poorly controlled diabetes include microvascular complications that affect the eyes (retinopathy, blindness), kidneys (nephropathy, renal failure), and nerves (neuropathy, peripheral and autonomic), as well as macrovascular complications that affect the cardiovascular system, increasing the risk of heart attacks and strokes fourfold compared to the nondiabetic population.
Industry:Science
Humans develop the disease cholera after ingesting water or food contaminated with the bacterium <i>Vibrio cholerae</i>. In parts of the world where cholera appears in a yearly cycle (endemic areas), <i>V. cholerae</i> is constantly present in the environment even when there is no disease. During cholera epidemics the microorganisms are acquired by human hosts and rapidly transmitted via the fecal-oral route from person to person.
When swallowed, <i>V. cholerae</i> colonizes the surface (epithelium) of the small intestine by using specialized adherence structures called toxin co-regulated pili or mannose-sensitive hemagglutinins (the sugar mannose specifically inhibits attachment in vitro). Then the vibrios release a potent enterotoxin that causes enterocytes to temporarily reverse their normal absorptive function and instead hypersecrete water and electrolytes. The resultant voluminous diarrhea can lead to lethal dehydration (cholera gravis); but because the infection is self limited (localized and short term), patients can be treated by simply using oral or intravenous fluid replacement.
Antibiotic treatment is not necessary, but it is often employed to eliminate vibrio shedding into the environment and to decrease the amount of replacement fluids required. Unfortunately, high mortality from cholera occurs in developing countries with inadequate treatment facilities.
Industry:Science
Electronic transmission systems are evolving with the expansion of broadcast satellite, cable, wireless (cellular, local area networks, and LMDS (local multipoint distribution service)), and satellite radio. While the systems are designed for transport of different types of media, convergence is changing this aspect of the systems. More importantly, these systems share the common feature of being multiple-access systems. These transmission systems allow new applications ranging from very small amounts of information directed at a single user to incredibly large amounts of information directed at a large but selective group of individuals.
With these capabilities comes the responsibility to provide security, protecting the property of the content providers and service providers as well as maintaining the privacy demanded by the individual subscribers or users. The conditional access of information involves the three A's: auditing (identifying what has been accessed by whom), authorization (addressing the information only to those entitled to receive it), and authentication (guaranteeing the identity of all the parties involved). This article addresses the threats to modern electronic transmission systems as well as the mechanisms used to prevent these threats. While each system has its unique problems, the generic issues associated with most of the systems will be treated here.
Industry:Science
Hibernation is a seasonal period of extremely low metabolic activity that permits certain animals to survive winter, when little or no food is available. Most hibernators accumulate large amounts of fat over the summer and fall to use as the primary fuel source during the hibernation season. By also reducing energy expenditure and living below ground in burrows, they can survive winter when there is heavy snowfall and air temperature hovers near freezing. Hibernation is, however, only one type of winter dormancy.
A season of relative inactivity occurs in a vast array of plants and animals. A type of winter dormancy occurs in several species of insects, amphibians, reptiles, birds, and mammals. Only one avian species is known to hibernate, although other species become hypometabolic for several hours each day during the winter. It is generally agreed that the primary function of winter dormancy, and hence hibernation, is to conserve energy during an energetically challenging time of year when little or no food is available. Dormant ectotherms remain hypometabolic throughout the entire winter and become active again in the spring when high ambient temperatures return. In contrast, in mammals a season of hibernation is characterized by prolonged intervals (days or weeks) of hypometabolism that alternate with brief intervals of high metabolism (less than 24 h) over the course of 5–6 months.
Industry:Science
Free-surface and multiphase flows are relevant to a variety of industrial and natural processes. At relatively small spatial scales, droplet impacts with solid surfaces are important for spray cooling, ink-jet printers, film coating, spray painting, erosion in steam turbines, and soil erosion due to rainfall. In fuel sprays the disintegration of liquid jets is attained via primary breakup of the fluid column and secondary breakup of the generated droplets. To optimize the injection systems and the subsequent combustion, it is crucial to determine the drop size distribution function. The interaction of a large number of droplets is relevant to boiling water–steam flows in pipes and to rain formation. At greater scales the wind is responsible for the wave formation and breaking on the ocean surface.
Finding the flow around an advancing ship is a difficult free-surface problem whose solution would bring large rewards in design and optimization. All these processes are quite complex in themselves, but it is also necessary to couple the fluid dynamics description to other effects such as the chemistry of combustion or solid mechanics, for example, to determine the stress tensor in the hull of a fast ship moving in rough seas. Experimental techniques have shown the intrinsic beauty of drop impact, formation, and coalescence to such an extent that these processes are widely used in commercial advertisements.
Industry:Science
Cloud microphysical parameterizations are techniques for representing sub-grid-scale microphysical processes using grid-scale information in atmospheric cloud-scale-resolving numerical models. A multimoment cloud microphysical parameterization is one that uses two or more of the following moments including, but not limited to, number concentration (number of hydrometeors per unit volume), characteristic diameter of hydrometeor size distribution (inverse of slope of size distribution), mixing ratio (hydrometeor density divided by density of air), and reflectivity (related to radiation power scattered back to a radar) to predict the evolution of aerosols, clouds, and precipitation.
The prediction of changes in aerosols, clouds, and precipitation involves the development of parameterizations of processes such as nucleation (initiation of cloud particles with or without aerosols), vapor diffusion growth (loss or gain of hydrometeor mass owing to a phase change of water vapor), collection and breakup (one type of particle collecting another and destruction of hydrometeors by collisions), freezing (phase change of liquid water to ice), melting (phase change from ice water to liquid), and sedimentation (fallout of hydrometeors, usually at their terminal velocities). The prediction of aerosols and hydrometeors also requires the need for numerical approximations for positive-definite solutions to transport and turbulent mixing.
Industry:Science
Endoplasmic reticulum quality control is a vital process in all eukaryotic cells that ensures that only properly folded proteins leave the endoplasmic reticulum for transport to their final destination. Under normal cellular conditions, molecular chaperones and lectins recognize aberrant or unfolded proteins and target them for destruction in a procedure known as endoplasmic reticulum–associated degradation. However, when genetic mutations, translational errors, or cell stress lead to a toxic accumulation of unfolded proteins in the endoplasmic reticulum, this degradation process may be insufficient to prevent aggregation or blockage of the endoplasmic reticulum transport machinery, and a signal transduction pathway termed the unfolded protein response is activated. This pathway leads to increased synthesis of folding and degradative enzymes while decreasing overall new protein synthesis, which allows the endoplasmic reticulum to better handle the load of unfolded protein. If endoplasmic reticulum stress cannot be abated, apoptotic pathways can be initiated, ultimately leading to cell death.
Notably, much of the early research to discern the mechanisms of endoplasmic reticulum–associated degradation and the unfolded protein response was done in baker's yeast, <i>Saccharomyces cerevisiae</i>. All of the yeast components of these processes have homologs in mammals, although the mammalian systems are somewhat more complex.
Industry:Science
Crewed space flight, especially aboard spacecraft in low Earth orbit, is now commonplace. The space shuttle, able to carry the <i>Spacelab</i> module in its payload bay, provides an orbiting scientific laboratory in which scientists and astronauts can perform experiments in a low-acceleration (or nearly weightless) environment. Doing science in space is important for two reasons.
First, as more people work and live in a weightless environment, practical knowledge of how systems, materials, and even the human body perform in and respond to extended exposure to low gravity is critical to continued space exploration. Thus, many applied-science experiments are performed aboard the shuttle to gain insight into the effects of long-term weightlessness.
Second, the Earth's gravity is a dominant and pervasive force in ground-based laboratories and, in the case of experiments in fluids, can mask more subtle forces. In the relative absence of thermal and buoyant convection and their effects in orbit, surface tension becomes the dominant fluid force, and ideal experiments can be performed to provide absolute and rigorous tests of fluid-dynamic theories, which would be impossible on the ground. In one such experiment, liquid drops nearly 2.5 cm (1 in.) in diameter were allowed to float aboard the space shuttle, where they were deformed by an acoustic standing wave and then released to execute free oscillations about a perfect spherical equilibrium.
Industry:Science
Elevation of triglycerides (hypertriglyceridemia) is an independent risk factor for atherosclerosis-related cardiovascular disease. Similar to low-density lipoproteins (LDLs), triglyceride-rich lipoproteins (TRLs) accumulate in atherosclerotic plaques. Hypertriglyceridemia is associated with an overproduction of very low density lipoprotein (VLDL) particles or delayed catabolism of TRLs, their remnants, and apolipoprotein B (ApoB)–containing lipoproteins. (An apolipoprotein is a protein that combines with a lipid (fat) to form a lipoprotein.)
The delayed catabolism of TRLs and their remnants is a direct consequence of reduced lipoprotein lipase activities, hepatic (liver) remnant receptors, and increased apolipoprotein C-III (ApoC-III) levels. ApoC-III resides on a broad distribution of ApoB lipoproteins, including chylomicrons (very large lipoproteins rich in triglycerides, found in blood after the ingestion of fat), VLDLs, LDLs, and high-density lipoproteins (HDLs). It is the major regulator of lipolysis (the enzyme-catalyzed hydrolysis (removal) of fatty acids from triglycerides), noncompetitively inhibiting endothelial-bound lipoprotein lipase, which is the enzyme that hydrolyzes triacylglycerols in TRLs. ApoC-III can also inhibit hepatic lipase as well as the uptake of triacylglycerol-rich lipoprotein remnants by hepatic lipoprotein receptors. In addition, it has direct cellular effects that can contribute to cardiovascular disease.
Industry:Science
Both microorganisms and higher organisms display a variety of motile responses to light as an environmental signal. Such light-elicited motility responses are generally referred to as photomovement. The organisms use the photomovement to adapt to optimal physiological and growth conditions. Phototaxis refers to the movement of a motile organism toward (positive phototaxis) or away from (negative phototaxis) the source of light. Rigorously speaking, the positive and negative phototaxis refers to the organism's response with respect to the direction of light source. However, the term phototaxis often is used in reference to the light-elicited movement behavior of a population of organisms toward or away from the source of light, which may or may not be in response to the direction of light propagation. Phototaxis can result from different mechanisms of the light-elicited movement.
For example, an individual ciliate cell may stop its swimming upon encountering a sudden increase in light intensity, and it then steers away from the higher to the lower light intensity area. This response is called step-up photophobic response, and results in a negative phototaxis, as the cell swims away from the high-intensity light. To define various light-elicited movements of organisms that may result in phototaxis, it is necessary to discuss various photomovement responses. The photomovements of specific ciliates and bacteria will be used as typical examples.
Industry:Science
