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One reason we are able to recognize speech, despite all the acoustic variation in the signal, and even in very difficult listening conditions, is that the speech situation contains a great deal of redundancy-more information than is strictly necessary to decode the message. There is, firstly, our general ability to make predictions about the nature of speech, based on our previous linguistic experience-our knowledge of the speakers, subject matter, language, and so on. But in addition, the wide range of frequencies found in every signal presents us with far more information than we need in order to recognize what is being said. As a result, we are able to focus our auditory attention on just the relevant distinguishing features of the signal-features that have come to be known as acoustic cues.

What are these cues, and how can we prove their role in the perception of speech? It is not possible to obtain this information simply by carrying out an acoustic analysis of natural speech: this would tell us what acoustic information is present but not what features of the signal are actually used by listeners in order to identify speech sounds. The best an acoustic description can do is give us a rough idea as to what a cue might be. But to learn about listener`s perception, we need a different approach.
The primary purpose of the passage is to
The `trophic contamination hypothesis` posits that shorebirds accumulate industrial and urban pollution at stopover sites, toxins that are subsequently released in sudden high doses as fat is burned during migratory flights, disrupting the bird`s ability to make migratory decisions. For example, large contaminant doses might hamper refueling by reducing the satiation signal in shorebirds so that they do not accumulate sufficient fat for migration. A recent study found that, out of those shorebirds that were unable to migrate, some weighed as much as 20% less than the average migrating bird of their species. Whether such findings are a result of shorebirds suffering from trophic contamination, or whether such birds simply cut their migrations short by landing in a foreign ecosystem is unlikely to be resolved until further studies are conducted.?

One promising line of research involves organochlorines, toxins deposited on mudflats in the 1970s and 1980s, now buried by sediments but finally close enough to the surface to be of issue to foraging shorebirds. Organochlorines should be more accessible to long-billed shorebirds that probe deeply for prey than to short-billed species that forage at or near the surface. We predict that an increased number of long-billed shorebirds will either be unable to migrate or will be found along an aberrant flight path.
According to the passage, the long-billed shorebird is expected to be more likely than the short-billed shorebird to have trouble migrating because
Dark matter and dark energy have little effect on conventional matter over familiar distances. Instead, they make their presence known through their prodigious gravitational effects. In tracking them down, therefore, astronomers have had to study gigantic assemblages of matter, extending across spans of millions and billions of light-years. Perhaps the first to take that sweeping viewpoint was the Swiss-American astronomer Fritz Zwicky. In the 1930`s, Zwicky traced the motions of individual galaxies within great clusters of galaxies and made a remarkable discovery: the individual galaxies are moving too fast to be held together in a cluster by the force of gravity exerted by the starry matter visible within them. From his measurements, Zwicky concluded that the great clusters of galaxies must be held together by the gravitational effect of some unseen mass, which he dubbed "dark matter."
Scientists studied "gigantic assemblages of matter, extending across spans of millions and billions of light-years" in order to
The digital revolution has given us, for the first time, the image in its pure form, an image without body. The image conveyed by a painting, on the other hand, is always a material entity, however unobtrusive, a particular thing made out of pigments, binders and a support. Sculpture, in turn, is often far more physically obtrusive than painting, and to the extent that it offers a multiplicity of possible viewpoints, it generates many images, but typically none of them are the image of the work. The physical impression a sculpture makes is more powerful than its imagistic content, which seems merely transitory by comparison. The digitization of culture has only made this more evident.
Which of the following best accounts for why sculpture is not amenable to digitized form?
In the twentieth century, the visual arts have embarked on major experimentation, from cubism to expressionism. While tastes always vary, there are certainly some people who find beautiful objects of each of the art movements of the first half of the twentieth century. In the latter half of the twentieth century, though, most works are so abstract or shocking that neither the critic nor the general public uses the word "beautiful" to describe them: indeed, sometimes late twentieth-century artists have, as one of their expressed goals, the creation of a work that no one?could?find beautiful. Whatever these artists are creating may be intellectually engaging at some level, but it is no longer art.
Which of the following is an assumption that supports drawing the conclusion above from the reasons given for that conclusion?
Oceanologist:?Recently an unprecedented number of dead dolphins washed ashore along the mid-Atlantic coast. In the blood of over half of the dolphins, marine biologists discovered a brevotoxin that had been emitted by the alga?Ptychodiscus brevis,?in what is known as a red tide. Additionally, polychlorinated biphenyls (PCB), a toxic industrial compound, was also found in the dolphin`s blood. A reasonable conclusion, and indeed one many have drawn, is that the dolphins were simply victims of the brevotoxin. Nonetheless, brevotoxins, by themselves, are not lethal to dolphins, though they do tax the dolphins system. Furthermore, most dolphins have some accumulated brevotoxins in their blood without suffering any ill health effects. Therefore, the brevotoxins alone cannot explain the mass beaching of dead dolphins.
Which of the following, if true, does most to help explain the oceanologist`s doubt that the brevotoxins were the primary cause of the dolphins washing upon shore?
Riders who wear bicycle helmets can greatly reduce the risk of significant injury. Therefore, doctors working in an emergency room can expect that out of cyclists admitted to hospitals those wearing bicycle helmets will have injuries that are less severe than those not wearing a helmet.
Which of the following is necessary to evaluate the argument?
Compared to regulations in other countries, those of the United States tends to be narrower in scope, with an emphasis on manufacturing processes and specific categories of pollution, and little or no attention to the many other factors that affect environmental quality. An example is the focus on controlling pollution rather than influencing decisions about processes, raw materials, or products that determine environmental impacts. Regulation in the United States tends to isolate specific aspects of production processes and attempts to control them stringently, which means that some aspects of business are regulated tightly, although sometimes not cost-effectively, while others are ignored. Other countries and several American states have recently made more progress in preventing pollution at its source and considering such issues as product life cycles, packaging waste, and industrial energy efficiency.

Environmental regulation in the United States is also more prescriptive than elsewhere, in the sense of requiring specific actions, with little discretion left to the regulated firm. There also is a great reliance on action-forcing laws and technology standards.

These contrasts are illustrated nicely in a 1974 book that used a hare and tortoise analogy to compare air quality regulation in the United States and Sweden. While the United States (the hare) codified ambitious goals in statutes that drove industry to adopt new technologies under the threat of sanctions, Sweden (the tortoise) used a more collaborative process that stressed results but worked with industry in deciding how to achieve them. In the end air quality results were about the same. Similar results have been found in other comparative analyses of environmental regulation. For example, one study of a multinational firm with operations in the United States and Japan found that pollution levels in both countries were similar, despite generally higher pollution abatement expenditures in the United States. The higher costs observed in the United States thus were due in large part, not to more stringent standards, but to the higher regulatory transaction costs. Because agencies in different countries share information about technologies, best practices, and other issues, the pollution levels found acceptable in different countries tends to be quite similar.
According to the passage, as a result of stringent regulation of specific aspects of the production process other aspects of the production process are
In Metroville, the KP subway line follows the riverfront from downtown to the neighborhoods surrounding the university. ?No matter how many trains the subway runs on the KP line, there are always congestion and delays on the KP line. ?The subway submitted a proposal for an alternate subway line that would travel from downtown to the neighborhoods surrounding the university via the inland neighborhoods, hoping to draw some of the congestion from the KP line. ?The city hired urban planning consultants who concluded the subway's proposal of a new line would not reduce commuter congestion on the KP line.
Which of the following, if true, most helps to explain the urban planning consultants' position?
Originally, scientists predicted small asteroids to be hard and rocky, as any loose surface material (called regolith) generated by impacts was expected to escape their weak gravity. Aggregate small bodies were not thought to exist, because the slightest sustained relative motion would cause them to separate. But observations and computer modeling are proving otherwise. Most asteroids larger than a kilometer are now believed to be composites of smaller pieces. Those imaged at high-resolution show evidence for copious regolith despite the weak gravity. Most of them have one or more extraordinarily large craters, some of which are wider than the mean radius of the whole body. Such colossal impacts would not just gouge out a crater-they would break any monolithic body into pieces. In short, asteroids larger than a kilometer across may look like nuggets of hard rock but are more likely to be aggregate assemblages-or even piles of loose rubble so pervasively fragmented that no solid bedrock is left.

The rubble hypothesis, proposed decades ago by scientists, lacked evidence, until the planetologist Shoemaker realized that the huge craters on the asteroid Mathilde and its very low density could only make sense together: a porous body such as a rubble pile can withstand a battering much better than an integral object. It will absorb and dissipate a large fraction of the energy of an impact; the far side might hardly feel a thing. At first, the rubble hypothesis may appear conceptually troublesome. The material strength of an asteroid is nearly zero, and the gravity is so low one is tempted to neglect that too. The truth is neither strength nor gravity can be ignored. Paltry though it may be, gravity binds a rubble pile together. And anybody who builds sandcastles knows that even loose debris can cohere. Oft-ignored details of motion begin to matter: sliding friction, chemical bonding, damping of kinetic energy, etc. We are just beginning to fathom the subtle interplay of these minuscule forces.

The size of an asteroid should determine which force dominates. One indication is the observed pattern of asteroidal rotation rates. Some collisions cause an asteroid to spin faster; others slow it down. If asteroids are monolithic rocks undergoing random collisions, a graph of their rotation rates should show a bell-shaped distribution with a statistical "tail" of very fast rotators. If nearly all asteroids are rubble piles, however, this tail would be missing, because any rubble pile spinning faster than once every two or three hours would fly apart. Recently, several astronomers discovered that all but five observed asteroids obey a strict rotation limit. The exceptions are all smaller than about 150 meters in diameter, with an abrupt cutoff for asteroids larger than 200 meters. The evident conclusion-that asteroids larger than 200 meters across are rubble piles-agrees with recent computer modeling of collisions. A collision can blast a large asteroid to bits, but those bits will usually be moving slower than their mutual escape velocity (the lowest velocity that a body must have in order to escape the orbit of a planet). Over several hours, gravity will reassemble all but the fastest pieces into a rubble pile.
According to the rubble-pile hypothesis, an advantage conferred on an asteroid held together by weak forces is that it is
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