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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.
Bioluminescence is the emission of photons of visible light by living organisms via the chemical reaction of molecular oxygen (O<sub>2</sub>) with a substrate (luciferin) catalyzed by an enzyme (luciferase). Organisms that exhibit bioluminescence are diverse and widely distributed in nature, for example, bacteria, dinoflagellates, fungi, insects (such as click beetles and fireflies), and fish. (Some fish, such as deep-sea angler fish, exhibit bioluminescence through bioluminescent bacterial symbionts, whereas others, such as hatchet fish, exhibit bioluminescence on their own.) The colors of the light produced by bioluminescent organisms differ; for example, bacteria emit a blue-green light (490 nm) and fireflies emit a yellow light (560 nm). The enzymes that catalyze the bioluminescence reaction show no homology to each other, and the substrates are also chemically unrelated. Molecular oxygen is the only common feature of bioluminescence reactions, indicating that the luminescent systems in most organisms may have evolved independently. The terms “luciferase” and “luciferin” are thus generic terms for the enzymes and substrates involved in the different bioluminescent reactions.
Industry:Science
For any system, that is, the volume of substance under discussion, enthalpy is the sum of the internal energy of the system plus the system's volume multiplied by the pressure exerted by the system on its surroundings. This may be expressed as <i>U</i> + <i>PV</i> = <i>H</i>, where <i>U</i> is the system's internal energy, <i>P</i> the pressure of the system, <i>V</i> the system's volume, and <i>H</i> the enthalpy of the system. The sum of <i>U</i> + <i>PV</i> is given the special symbol <i>H</i> primarily as a matter of convenience because this sum appears repeatedly in thermodynamic discussion. Consistent units must, of course, be used in expressing the terms in the above equation. Previously, enthalpy was referred to as total heat or heat content, but these terms are misleading and should be avoided. Enthalpy is, from the viewpoint of mathematics, a point function, as contrasted with heat and work, which are path functions. Point functions depend only on the initial and final states of the system undergoing a change; they are independent of the paths or character of the change. Mathematically, the differential of a point function is a complete or perfect differential.
Industry:Science
Approximately 1 in 1000 children is born with a functionally significant, permanent hearing loss, and about 1 in 500 will have a hearing loss by the age of 9. Audiologic testing demonstrates that this hearing loss is attributable to dysfunction of the inner ear or the auditory nerve. Approximately one-half of these cases are caused by environmental factors such as infections, and the other half are genetic in origin. One-third of genetic cases are inherited as part of a syndrome that affects other organ systems. The other two-thirds exhibit hearing loss as the only clinical feature and are termed nonsyndromic. Early observations of relatively high frequencies of normal-hearing offspring born to two parents with nonsyndromic deafness indicated that there were many different genes in which mutations could cause hearing loss. Although hearing loss is increasingly prevalent among older adults, affecting as many as one in two individuals by the age of 80, the genetic basis of this age-related hearing loss, presbycusis, is not well understood. There is a genetic component, but the genetic basis appears to be complex and may involve more than one gene in any individual with presbycusis.
Industry:Science
Every cell in our body contains genetic information for its proper functioning. This information is present in the long stretch of nucleotides—adenosine (A), cytosine (C), guanosine (G), and thymidine (T)—that form our DNA (deoxyribonucleic acid). Several hundreds to thousands of these A, C, G, and T nucleotides contain the information for one gene, and our DNA contains more than 30,000 genes. Each of these genes has to be intact for proper functioning. However, the integrity of our DNA is threatened by many different agents, such as sunlight, chemicals, and even the oxygen in the air. If damaged DNA were left unrepaired, the cells of our body would quickly lose essential gene functions and life would not be possible. However, all living organisms contain a multitude of enzymes that counteract such damage and restore the proper DNA sequence. Failure of these DNA repair functions can lead to various diseases, such as cancer and developmental disorders. In recent years, considerable progress has been made in understanding the various DNA repair pathways. We are now on the verge of an era in which this knowledge can be exploited to develop more effective and specific anticancer drugs.
Industry:Science
For 1.5 to 2.5 billion people in the world, lack of clean water is a critical issue. It is estimated that by the year 2025 there will be an additional 2.5 billion people who will live in regions already lacking sufficient clean water. In the United States today, it is estimated that 90% of citizens live within 10 mi of a body of contaminated water. Large numbers of point (single, identifiable) and nonpoint sources having low flow volume (50 gal (190 L) per minute or less) contribute significantly to these water contamination problems. These sites pose a major unsolved problem because they also can be intermittent, reducing the cost effectiveness of many current mitigation technologies. The northeastern United States—with its large population, concentrated residential areas, industrial sites, livestock confinement operations, and the like—has many such sites where low-volume-flow water runoff and discharges need to be treated. In addition, it is estimated that there are approximately 500,000 abandoned hard-rock mine sites in the United States, many of them located in or near watersheds where acid mine drainage may release heavy metals into thousands of public drinking-water systems.
Industry:Science
Functional neuroimaging of healthy adults has enabled the mapping of brain functions and revolutionized cognitive neuroscience. Increasingly, functional neuroimaging is being used as a diagnostic and prognostic tool in the clinical setting and to view brain development. Its expanding application in the study of disease and development necessitates new, more flexible tools. The logistics of traditional functional brain scanners (for example, magnetic resonance imaging (MRI) systems) are not well suited to subjects who are in an intensive-care unit or who might otherwise require sedation for imaging, such as infants and young children. Diffuse optical imaging (DOI)—an emerging, noninvasive technique with unique portability and hemodynamic (blood circulation) contrast capabilities—can record evoked brain function in clinical environments. However, despite its unique strengths, DOI as a standard tool for functional mapping has been limited by low spatial resolution, limited depth penetration, and a lack of reliable and repeatable mapping. To address these weaknesses, there recently has been significant interest in applying tomographic optical approaches to the problem of imaging brain function.
Industry:Science
Any chemical used to destroy or inhibit plant growth, especially of weeds or other undesirable vegetation. The concepts of modern herbicide technology began to develop about 1900 and accelerated rapidly with the discovery of dichlorophenoxyacetic acid (2,4-D) as a growth-regulator-type herbicide in 1944–1945. A few other notable events should be mentioned. During 1896–1908, metal salts and mineral acids were introduced as selective sprays for controlling broad-leafed weeds in cereals; during 1915–1925 acid arsenical spray, sodium chlorate, and other chemicals were recognized as herbicides; and in 1933–1934, sodium dinitrocresylate became the first organic selective herbicide to be used in culture of cereals, flax, and peas. Since the introduction of 2,4-D, a wide variety of organic herbicides have been developed and have received wide usage in agriculture, forestry, and other industries. Today, the development of highly specific herbicides that are intended to control specific weed types continues. Modern usage often combines two or more herbicides to provide the desired weed control. Worldwide usage of herbicides continues to increase, making their manufacture and sale a major industry.
Industry:Science
For millennia, physicians' literature has addressed means of ensuring that purchased medicines are what they are claimed to be. Herbs are much more likely than cultivated vegetables to be accidentally confused: most botanicals are not highly modified in form and may closely resemble related or even unrelated species, and many are collected from the wild, where similar-looking species may also occur. Furthermore, inexpensive botanicals have sometimes been fraudulently substituted for or commingled with rare and costly botanicals. While most botanicals are correctly identified, substitution of the wrong species can cause serious harm. At worst, people have been poisoned after using a toxic species that was confused with an unrelated plant; in a relatively recent case, contamination of cultivated plantain with digitalis resulted in several reported illnesses. More commonly, the substituted plant may provide the consumer lesser benefits than the desired species, or none at all. In modern practice, every marketer of crude botanicals or manufacturer of botanical products should have explicit quality-control procedures to ensure that materials sold are correctly identified and of acceptable purity.
Industry:Science
Certain mushrooms have long been valued as flavorful and nutritious foods by many societies worldwide. Furthermore, some of these societies, especially in the Far East, have long recognized that extracts from certain mushroom species possess health-promoting benefits and, consequently, use them as ingredients in many herbal medicines, such as traditional Chinese medicine (TCM). While approximately 14,000 species of mushrooms are believed to exist worldwide, at least 600 have been shown to possess various therapeutic properties, and the term “medicinal mushroom” is gaining worldwide recognition for such species. (The term medicinal mushroom was derived in the Far East but is now accepted, in broad terms, by Western medicine standards.) The most commercialized edible mushrooms that demonstrate principal medicinal or functional properties include species of <i>Lentinus</i>, <i>Hericium</i>, <i>Grifola</i>, <i>Flammulina</i>, <i>Pleurotus</i>, and <i>Tremella</i>, while others known only for their medicinal properties, such as <i>Ganoderma</i> spp., <i>Schizophyllum commune</i>, and <i>Trametes</i> (<i>Coriolus</i>) <i>versicolor</i>, are nonedible because of their coarse texture and bitter taste.
Industry:Science
Behavior related to the production of offspring; it includes such patterns as the establishment of mating systems, courtship, sexual behavior, parturition, and the care of young. Successful reproductive efforts require the establishment of a situation favorable for reproduction, often require behavior leading to the union of male and female gametes, and often require behavior that facilitates or ensures the survival and development of the young; the mere union of gametes is not generally sufficient for successful reproduction.
For each species, there is a complex set of behavioral adaptations that coordinate the timing and patterning of reproductive activity. Typically, this entails integration of both overt behavioral and internal physiological events in both male and female, all of which are intricately enmeshed in manners adapted to the environment in which the animals live. The behavioral patterns related to reproduction tend to be relatively stereotyped within a species, but diverse among different species—especially distantly related species. The end products of cycles of reproductive activity are viable, fertile offspring which, in turn, will reproduce and thus perpetuate the species.
Industry:Science
