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Although many lines of evidence indicate that birds evolved from ground-dwelling theropod dinosaurs, some scientists remain unconvinced. They argue that theropods appeared too late to have given rise to birds, noting that Archaeopteryx lithographic - the oldest known bird - appears in the fossil record about 150 million years ago, whereas the fossil remains of various nonavian maniraptor theropods - the closest known relatives of birds - date only to about 115 million years ago. But investigators have now uncovered bones that evidently belong to nonavian maniraptors dating to the time of Archaeopteryx. In any case, failure to find [hl:2]fossils of a predicted kind[/hl:2] does not rule out their existence in an undiscovered deposit. Skeptics also argue that the fused clavicles (the "wishbone") of birds differ from the unfused clavicles of theropods. This objection was reasonable when only early theropod clavicles had been discovered, but fossilized theropod clavicles that look just like the wishbone of Archaeopteryx have now been unearthed. Finally, some scientists argue that the complex lungs of birds could not have evolved from theropod lungs, an assertion that cannot be supported or falsified at the moment, because no fossil lungs are preserved in the paleontological record.
Earth's surface consists of rigid plates that are constantly shifting and jostling one another. Plate movements are the surface expressions of motions in the mantle—the thick shell of rock that lies between Earth's crust and its metallic core. Although the hot rock of the mantle is a solid, under the tremendous pressure of the crust and overlying rock of the mantle, it flows like a viscous liquid. The mantle's motions, analogous to those in a pot of boiling water, cool the mantle by carrying hot material to the surface and returning cooler material to the depths. When the edge of one plate bends under another and its cooler material is consumed in the mantle, volcanic activity occurs as molten lava rises from the downgoing plate and erupts through the overlying one.Most volcanoes occur at plate boundaries. However, certain "misplaced" volcanoes far from plate edges result from a second, independent mechanism that cools the deep interior of Earth. Because of its proximity to Earth's core, the rock at the base of the mantle is much hotter than rock in the upper mantle. The hotter the mantle rock is, the less it resists flowing. Reservoirs of this hot rock collect in the base of the mantle. When a reservoir is sufficiently large, a sphere of this hot rock forces its way up through the upper mantle to Earth's surface, creating a broad bulge in the topography. The "mantle plume" thus formed, once established, continues to channel hot material from the mantle base until the reservoir is emptied. The surface mark of an established plume is a hot spot—an isolated region of volcanoes and uplifted terrain located far from the edge of a surface plate. Because the source of a hot spot remains fixed while a surface plate moves over it, over a long period of time an active plume creates a chain of volcanoes or volcanic islands, a track marking the position of the plume relative to the moving plate. The natural history of the Hawaiian island chain clearly shows the movement of the Pacific plate over a fixed plume.
[hl:5][hl:1][hl:2]Some historians[/hl:2][/hl:1] contend that conditions in the United States during the Second World War gave rise to a dynamic wartime alliance between trade unions and the African American community, an alliance that advanced the cause of civil rights. They conclude that the postwar demise of this vital alliance constituted a lost opportunity for the civil rights movement that followed the war.[/hl:5] [hl:1]Other scholars[/hl:1], however, have portrayed organized labor as defending all along the relatively privileged position of White workers relative to African American workers.[/hl:1] Clearly, these two perspectives are not easily reconcilable, but the historical reality is not reducible to one or the other. [hl:4]Unions faced a choice between either maintaining the prewar status quo or promoting a more inclusive approach that sought for all members the right to participate in the internal affairs of unions, access to skilled and high-paying positions within the occupational hierarchy, and protection against management's arbitrary authority in the workplace.[/hl:4] While union representatives often voiced this inclusive ideal, in practice unions far more often favored entrenched interests. The accelerating development of the civil rights movement following the Second World War exacerbated the [hl:6]unions' dilemma[/hl:6], forcing trade unionists to confront contradictions in their own practices.
A pressing need in the study of organizations is for more research into how an organization's values (an organization's guiding principles and beliefs as perceived by its members) affect managerial decision-making. Traditional theories have been based on a "rational model," which focuses on the decision-maker and either ignores the organizational value climate or conveniently assumes that the organization's values are consistent or clearly prioritized. In reality, however, decisions are shaped not only by a manager's own values, but also by those of the corporate culture and of organizational superiors. A recent study found that managers' most stressful decisions involved "value contention" (conflicts among any of these sets of values). Furthermore, different types of organizational value systems were associated with different frequencies of contending values as well as with different types of managerial response. Explicit corporate values, for example, produced a greater percentage of decisions that were stressful due to value contention. Hidden values (those that an organization practices but does not acknowledge or which a superior furtively pursues in opposition to the values of the organization) produced a lower level of value contention. Although explicit values created more value contention, they were nonetheless more likely to produce flexible, well-reasoned decisions. Conversely, managers perplexed by hidden values reported feeling unable to identify an appropriate range of options.
More selective than most chemical pesticides in that they ordinarily destroy only unwanted species, biocontrol agents (such as insects, fungi, and viruses) eat, infect, or parasitize targeted plant or animal pests. However, biocontrol agents can negatively affect nontarget species by, for example, competing with them for resources: a biocontrol agent might reduce the benefits conferred by a desirable animal species by consuming a plant on which the animal prefers to lay its eggs.[hl:6]Another example of indirect negative consequences occurred in England when a virus introduced to control rabbits reduced the amount of open ground (because large rabbit populations reduce the ground cover), in turn reducing underground ant nests and triggering the extinction of a [hl:3]blue butterfly[/hl:3] that had depended on the nests to shelter its offspring.[/hl:6] The paucity of known extinctions or disruptions resulting from indirect interactions may reflect not the infrequency of such mishaps but rather the failure to look for or to detect them: most organisms likely to be adversely affected by indirect interactions are of little or no known commercial value and the events linking a biocontrol agent with an adverse effect are often unclear. Moreover, determining the potential risks of biocontrol agents before they are used is difficult, especially when a nonnative agent is introduced, because, unlike a chemical pesticide, a biocontrol agent may adapt in unpredictable ways, so that it can feed on or otherwise harm new hosts.
Grassland songbirds often nest in the same grassland-wetland complexes as waterfowl, particularly in a certain part of those complexes, namely, upland habitats surrounding wetlands. Although some wildlife management procedures directed at waterfowl, such as habitat enhancement or restoration, may also benefit songbirds , the impact of others, especially the control of waterfowl predators, remains difficult to predict. For example, most predators of waterfowl nests prey opportunistically on songbird nests, and removing these predators could directly increase songbird nesting success. Alternatively, small mammals such as mice and ground squirrels are important in the diet of many waterfowl-nest predators and can themselves be important predators of songbird nets. Thus. Removing waterfowl-nest predators could affect songbird nesting success through subsequent increases in small-mammal populations.In 1995 and 1996, researchers trapped and removed certain waterfowlnest predators. primary raccoons and striped skunks, then observed subsequent survival rates for songbird nests. Surprisingly. They observed no significant effect on songbird nesting success. This may be due to several factors. [hl:2]Neither raccoons nor striped skunks consume ground squirrels, which are important predators of songbird nests.[/hl:2] Thus, their removal may not have led to significant increases in populations of smaller predators. Additionally, both raccoons and striped skunks prefer wetlands and spend little time in upland habitats; removing these species may not have increased the nesting success of songbirds in the uplands enough to allow detection.
Findings from several studies on corporate mergers and acquisitions during the 1970's and 1980's raise questions about why firms initiate and consummate such transactions. One study showed, for example, that acquiring firms were on average unable to maintain acquired firms' pre-merger levels of profitability. A second study concluded that post-acquisition gains to most acquiring firms were not adequate to cover the premiums paid to obtain acquired firms. A third demonstrated that, following the announcement of a prospective merger, the stock of the prospective acquiring firm tends to increase in value much less than does that of the firm for which it bids. Yet mergers and acquisitions remain common, and bidders continue to assert that their objectives are economic ones. Acquisitions may well have the desirable effect of channeling a nation's resources efficiently from less to more efficient sectors of its economy, but the individual acquisitions executives arranging these deals must see them as advancing either their own or their companies' private economic interests. It seems that factors having little to do with corporate economic interests explain acquisitions. These factors may include the incentive compensation of executives, lack of monitoring by boards of directors, and managerial error in estimating the value of firms targeted for acquisition. Alternatively, the acquisition acts of bidders may derive from modeling: a manager does what other managers do.
Joseph Glarthaar's Forged in Battle is not the first excellent study of Black soldiers and their White officers in theCivil War, but it uses more soldiers' letters and diaries - including rare material from Black soldiers - and concenrates more intensely on Black-White relations in Black regiments than do any of its predecessors. Glathaar's title expresses his thesis: loyalty, friendship, and respect among White officers and Black soldiers were fostered by the mutual dangers they faced in combat.Glarthaar accurately describes the government's discriminatory treatment of Black soldiers in pay, promotion, medical care, and job assignments, appropriately emphasizing the campaign by Black soldiers and their officers to get the opportunity to fight. That chance remained limited throughout the war by army policies that kept most Black units serving in rear-echelon assignments and working in labor battalions. Thus, while their combat death rate was only one-third that of White units, their mortality rate from disease, a major killer in his war, was twice as great. Despite these obstacles, the courage and effectiveness of several Black units in combat won increasing respect frominitially skeptical or hostile White soldiers. As one White officer put it, "[hl:6]they have fought their way into the respect of all the army.[/hl:6]"In trying to demonstrate the magnitude of this attitudinal change, however, [hl:7]Glarthaar seems to exaggerate the pre-war racism of the White men who became officers in Black regiments.[/hl:7] "Prior to the war," he writes of these men, "virtually all of them held powerful racial prejudices." While perhaps true of those officers who joined Black units for promotion or other self-serving motives, this statement misrepresents the attitudes of the many abolitionists who became officers in Black regiments. Having spent years fighting against the race prejudice endemic in American society; they participated eagerly in this military experiment, which they hoped would help African Americans achieve freedom and post-war civil equality. By current standards of racial egalitarianism, these men's paternalism toward African Americans was racist. But to call their feelings "powerful racial prejudices" is to indulge in [hl:8]generational chauvinism[/hl:8] - to judge past eras by present standards.
Two divergent definitions have dominated sociologists' discussions of the nature of ethnicity. The first emphasizes the primordial and unchanging character of ethnicity. In this view, people have an essential need for belonging that is satisfied by membership in groups based on shared ancestry and culture. A different conception of ethnicity de-emphasizes the cultural component and defines ethnic groups as interest groups. In this view, ethnicity serves as a way of mobilizing a certain population behind issues relating to its economic position. While both of these definitions are useful, neither fully captures the dynamic and changing aspects of ethnicity in the United States. Rather, ethnicity is more satisfactorily conceived of as aprocess in which preexisting communal bonds and common cultural attributes are adapted for instrumental purposes according to changing real-life situations.One example of this process is the rise of participation by Native American people in the broader United States political system since the Civil Rights movement of the1960's. Besides leading Native Americans to participate more actively in politics (the number of Native American legislative officeholders more than doubled), this movement also evoked increased interest in tribal history and traditional culture. Cultural and instrumental components of ethnicity are not mutually exclusive, but rather reinforce one another.The Civil Rights movement also brought changes in the uses to which ethnicity was put by Mexican American people. In the 1960's, Mexican Americans formed community-based political groups that emphasized ancestral heritage as a way of mobilizing constituents. Such emerging issues as immigration and voting rights gave Mexican American advocacy groups the means by which to promote ethnic solidarity. Like European ethnic groups in the nineteenth-century United States, late-twentieth-century Mexican American leaders combined ethnic with contemporary civic symbols. In 1968 Henry Censors, then mayor of San Antonio, Texas, cited Mexican leader Benito Juarezas a model for Mexican Americans in their fight for contemporary civil rights. And every year, Mexican Americans celebrate Cinco de Mayo as fervently as many Irish American people embrace St. Patrick's Day (both are major holidays in the countries of origin), with both holidays having been reinvented in the context of the United States and linked to ideals, symbols, and heroes of the United States
Modern manufacturers, who need reliable sources of materials and technologically advancedcomponents to operate profitably, face an increasingly difficult choice between owning theproducers of these items (a practice known as backward integration) and buying from independentproducers. Manufacturers who integrate may reap short-term rewards, but they often restrict theirfuture capacity for innovative product development.Backward integration removes the need for some purchasing and marketing functions, centralizersoverhead, and permits manufacturers to eliminate duplicated efforts in research and development.Where components are commodities (ferrous metals or petroleum, for example), backwardintegration almost certainly boosts profits. Nevertheless, because product innovation meansadopting the most technologically advanced and cost-effective ways of making components,backward integration may entail a serious risk for a technologically active company-for example,a producer of sophisticated consumer electronics.A company that decides to make rather than buy important parts can lock itself into an outdatedtechnology. Independent suppliers may be unwilling to share innovations with assemblers withwhom they are competing. Moreover, when an assembler sets out to master the technology ofproducing advanced components, the resulting demands on its resources may compromise itsability to assemble these components successfully into end products. Long-term contracts withsuppliers can achieve many of the same cost benefits as backward integration withoutcompromising a company's ability to innovate.However, moving away from backward integration is not a complete solution either. Developinginnovative technologies requires independent suppliers of components to invest huge sums inresearch and development. The resulting low profit margins on the sale of components threaten thelong-term financial stability of these firms. Because the ability of end-product assemblers torespond to market opportunities depends heavily on suppliers of components, assemblers are oftenforced to integrate by purchasing the suppliers of components just to keep their suppliers inbusiness.
Biologists have advanced two theories to explain why schooling of fish occurs in so many fish species. Because schooling is particularly widespread among species of small fish, both theories assume that schooling offers the advantage of some protection from predators.Proponents of theory A dispute the assumption that a school of thousands of fish is highly visible. Experiments have shown that any fish can be seen, even in very clear water, only within a sphere of 200 meters in diameter. When fish are in a compact group, the spheres of visibility overlap. Thus the chance of a predator finding the school is only slightly greater than the chance of the predator finding a single fish swimming alone. Schooling is advantageous to the individual fish because a predator's chance of finding any particular fish swimming in the school is much smaller than its chance of finding at least one of the same group of fish if the fish were dispersed throughout an area.However, critics of theory A point out that some fish form schools even in areas where predators are abundant and thus little possibility of escaping detection exists. They argue that the school continues to be of value to its members even after detection. They advocate theory B, the "confusion effect," which can be explained in two different ways.Sometimes, proponents argue, predators simply cannot decide which fish to attack. This indecision supposedly results from a predator's preference for striking prey that is distinct from the rest of the school in appearance. In many schools the fish are almost identical in appearance, making it difficult for a predator to select one. The second explanation for the "confusion effect" has to do with the sensory confusion caused by a large number of prey moving around the predator. Even if the predator makes the decision to attack a particular fish, the movement of other prey in the school can be distracting. The predator's difficulty can be compared to that of a tennis player trying to hit a tennis ball when two are approaching simultaneously.
While the most abundant and dominant species within a particular ecosystem is often crucial in perpetuating the ecosystem, a "keystone" species, here defined as one whose effects are much larger than would be predicted from its abundance, can also play a vital role. But because complex species interactions may be involved, identifying a keystone species by removing the species and observing changes in the ecosystem is problematic. It might seem that certain traits would clearly define a species as a keystone species; for example, Pisaster ochraceus is often a keystone predator because it consumes and suppresses mussel populations, which in the absence of this starfish can be a dominant species. But such predation on a dominant or potentially dominant species occurs in systems that do as well as in systems that do not have species that play keystone roles. Moreover, whereas P. ochraceus occupies an unambiguous keystone role on wave-exposed rocky headlands, in more wave-sheltered habitats the impact of P. ochraceus predation is weak or nonexistent, and at certain sites sand burial is responsible for eliminating mussels. Keystone status appears to depend on context, whether of particular geography or of such factors as community diversity (for example, a reduction in species diversity may thrust more of the remaining species into keystone roles) and length of species interaction (since newly arrived species in particular may dramatically affect ecosystems).
The idea of the brain as an information processor—a machine manipulating blips of energy according to fathomable rules—has come to dominate neuroscience. However, one enemy of the brain-as-computer metaphor is John R. Searle, a philosopher who argues that since computers Simply follow algorithms, they cannot deal with important aspects of human thought such as meaning and content. Computers are syntactic, rather than semantic, creatures. People, on the other hand, understand meaning because they have something Searle obscurely calls the causal powers of the brain.Yet how would a brain work if not by reducing what it learns about the world to information—some kind of code that can be transmitted from neuron to neuron? What else could meaning and content be? If the code can be cracked, a computer should be able to simulate it, at least in principle. But even if a computer could simulate the workings of the mind, Searle would claim that the machine would not really be thinking; it would just be acting as if it were. His argument proceeds thus: if a computer were used to simulate a stomach, with the stomach's churnings faithfully reproduced on a video screen, the machine would not be digesting real food. It would just be blindly manipulating the symbols that generate the visual display.Suppose, though, that a stomach were simulated using plastic tubes, a motor to do the churning, a supply of digestive juices, and a timing mechanism. If food went in one end of the device, what came out the other end would surely be digested food. Brains, unlike stomachs, are information processors, and if one information processor were made to simulate another information processor, it is hard to see how one and not the other could be said to think. Simulated thoughts and real thoughts are made of the same element: information. The representations of the world that humans carry around in their heads are already simulations. To accept Searle's argument, one would have to deny the most fundamental notion in psychology and neuroscience: that brains work by processing information.
Women's grassroots activism and their vision of a new civic consciousness lay at the heart of social reform in the United States throughout the Progressive Era, the period between the depression of 1893 and America's entry into the Second World War. Though largely disenfranchised except for school elections, white middle-class women reformers won a variety of victories, notably in the improvement of working conditions, especially for women and children. Ironically, though, child labor legislation pitted women of different classes against one another. To the reformers, child labor and industrial home work were equally inhumane practices that should be outlawed, but, as a number of [hl:3]women historians have recently observed[/hl:3], working-class mothers did not always share this [hl:2]view[/hl:2]. Given the precarious finances of working-class families and the necessity of pooling the wages of as many family members as possible, working-class families viewed the passage and enforcement of stringent child labor statutes as a personal economic disaster and made strenuous efforts to circumvent child labor laws. Yet reformers rarely understood this resistance in terms of the desperate economic situation of working-class families, interpreting it instead as evidence of poor parenting. This is not to dispute women reformers' perception of child labor as a terribly exploitative practice, but their understanding of child labor and their legislative solutions for ending it failed to take account of the economic needs of working-class families.
Many United States companies believe that the rising cost of employees' health care benefits has hurt the country's competitive position in the global market by raising production costs and thus increasing the prices of exported and domestically sold goods. As a result, these companies have shifted health care costs to employees in the form of wage deductions or high deductibles. This strategy, however, has actually hindered companies' competitiveness. For example, cost shifting threatens employees' health because many do not seek preventive screening. Also, labor relations have been damaged: the percentage of strikes in which health benefits were a major issue rose from 18 percent in 1986 to 78 percent in 1989.Health care costs can be managed more effectively if companies intervene in the supply side of health care delivery just as they do with other key suppliers: strategies used to procure components necessary for production would work in procuring health care. For example, the make/buy decision--the decision whether to produce or purchase parts used in making a product--can be applied to health care. At one company, for example, employees receive health care at an on-site clinic maintained by the company. The clinic fosters morale, resulting in a low rate of employees leaving the company. Additionally, the company has constrained the growth of health care costs while expanding medical services.
What kinds of property rights apply to Algonquian family hunting territories, and how did they come to be? The dominant [hl:3][hl:2]view[/hl:2][/hl:3] in recent decades has been that family hunting territories, like other forms of private landownership, were not found among Algonquians (a group of North American Indian tribes) before contact with Europeans but are the result of changes in Algonquian society brought about by the European-Algonquian fur trade, in combination with other factors such as ecological changes and consequent shifts in wildlife harvesting patterns. [hl:3]Another view[/hl:3] claims that Algonquian family hunting territories predate contact with Europeans and are forms of private landownership by individuals and families. More recent fieldwork, however, has shown that individual and family rights to hunting territories form part of a larger land-use system of multifamilial hunting groups, that rights to hunting territories at this larger community level take precedence over those at the individual or family level, and that this system reflects a concept of spiritual and social reciprocity that conflicts with European concepts of private property. In short, there are now strong reasons to think that it was erroneous to claim that Algonquian family hunting territories ever were, or were becoming, a kind of private property system.
Solar ponds are bodies of water in which circulation is incomplete and there is a very high salt concentration that increases with depth. This vertical change in salinity serves to trap heat because concentrated brine in the lowest water level acts as a collector and storage area for solar heat, while the less saline, lighter water at the upper levels provides insulation. Heat is thus retained in the depths.An artificial pond of this type has been constructed on the western shore of the Dead Sea in Israel in order to test its suitability as a source of low-grade heat for conversion into electricity. An immediate threat to the success of the venture was the growth of algae. Water in solar ponds must be kept maximally transparent to allow penetration of light to the deep storage area. Therefore, any particles of matter in the water, such as algae cells, that scatter or absorb light will interfere with the collection of heat.One proposed method of controlling the algae was the application of an algicide. However, the Dead Sea is a closed body of water without any outlet and as such is very easily contaminated. Extensive use of chemicals in numerous future full-scale solar ponds would lead to such contamination of the Dead Sea, which now enjoys a lucrative tourist trade.A recent experiment has supplied a more promising method for controlling the algae. To repress the algae cells' capacity for accommodating themselves to environmental changes, the water in the solar pond was first made more saline through evaporation and then diluted by a rapid inflow of fresh water. This shock reduced the cells' ability to regulate the movement of water through their membranes. They rapidly absorbed water, resulting in distortions of shape, increase in volume, and impairment to motility. Their buoyancy adversely affected, the cells sank to the bottom of the pond, where they encountered the hot waters of the storage layer and were destroyed. This method allows for effective control of nuisance algae while leaving solar ponds as one of the cleanest technologies providing energy for human use.
From the earliest days of the tribe, kinship determined the way in which the Ojibwa society organized its labor, provided access to its resources, and defined rights and obligations involved in the distribution and consumption of those resources.
PREP08 Test 1 Noting that the Federal Reserve had raised a key short-term interest rate again last month, analysts said that they expected orders for durable goods to decline soon because rising interest rates makes it more expensive to buy them on credit
GWD PREP08 Test 2 In archaeology, there must be a balance between explanation of the value and workings of archaeology, revealing the mysteries of past and present cultures, and to promote respect for archaeological sites.