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Most farmers attempting to control slugs and snails turn to baited slug poison, or molluscicide, which usually consists of a bran pellet containing either methiocarb or metaldehyde. Both chemicals are neurotoxins that disrupt that part of the brain charged with making the mouth move in a coordinated fashion - the "central pattern generator" - as the slug feeds. Thus, both neurotoxins, while somewhat effective, interfere with the slugs' feeding behavior and limit their ingestion of the poison, increasing the probability that some will stop feeding before receiving a lethal dose. Moreover, slugs are not the only consumers of these poisons: methiocarb may be toxic to a variety of species, including varieties of worms, carabid beetles, and fish.Researchers are experimenting with an [hl:4]alternative compound[/hl:4] based on aluminum, which may solve these problems, but this may well have a limited future as we learn more about the hazards of aluminum in the environment. For example, some researchers suggest that acid rain kills trees by mobilizing aluminum in the soil, while others have noted that the human disease Alzheimer's is more prevalent in areas where levels of aluminum in the soil are high. With farmers losing as much as 20 percent of their crops to slugs and snails even after treatment with currently available molluscicides, there is considerable incentive for researchers to come up with better and environmentally safer solutions.
190310 The bottom surface of the inverted conical vessel is parallel to the horizontal plane. The height of the cone is twice of the radius of the bottom. The container is partially filled with water. There is a small hole at the tip of the conical container. The speed of water leakage is 2cm^3/min. How long does it take for the water in the container to run out?
1: The water surface area is 9 π cm2
2: The distance between the water surface and the bottom of the container is 4 cm
Determining whether a given population of animals constitutes a distinct species can be difficult because no single accepted definition of the term exists. One approach, called the biological species concept, bases the definition on reproductive compatibility. According to this view, a species is a group of animals that can mate with one another to produce fertile offspring but cannot mate successfully with members of a different group.Yet this idea can be too restrictive. [line:10][hl:4]First, mating between groups labeled as different species (hybridization), as often occurs in the canine family, is quite common in nature.[/hl:4][/line:10] Second, sometimes the differences between two populations might not prevent them from interbreeding, even though they are dissimilar in traits unrelated to reproduction; some biologists question whether such disparate groups should be considered a single species. A third problem with the biological species concept is that investigators cannot always determine whether [line:21][hl:2]two groups that live in different places[/hl:2][/line:21] are capable of interbreeding. When the biological species concept is difficult to apply, some investigators use phenotype, an organism's observable characteristics, instead. Two groups that have evolved separately are likely to display measurable differences in many of their traits, such as skull size or width of teeth. If the distribution of measurements from one group does not overlap with those of another, the two groups might reasonably be considered distinct species.
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Cruise Cancellation Fees

Days Prior to Departure

Percent of Package Price
61 or more 10%
46 − 60 25%
31 − 45 40%
6 − 30 60%
5 or fewer 100%

 

The table above shows the cancellation fee schedule that a cruise company uses to determine the fee charged to a tourist who cancels a trip prior to departure. If a tourist canceled a trip with a package price of $3,800 and a departure date of August 5, on what day was the trip canceled?

(1) The cancellation fee was $950.

(2) If the trip had been canceled one day later, the cancellation fee would have been $570 more.
One [hl:2]proposal[/hl:2] for preserving rain forests is to promote the adoption of new agricultural technologies, such as improved plant varieties and use of chemical herbicides, which would increase productivity and slow deforestation by reducing demand for new cropland. Studies have shown that farmers in developing countries who have achieved certain levels of education, wealth, and security of land tenure are more likely to adopt such technologies. But these studies have focused on villages with limited land that are tied to a market economy rather than on the relatively isolated, self-sufficient communities with ample land characteristic of rain-forest regions. A recent [hl:4][hl:3]study[/hl:3][/hl:4] of the Tawahka people of the Honduran rain forest found that farmers with some formal education were more likely to adopt improved plant varieties but less likely to use chemical herbicides and that those who spoke Spanish (the language of the market economy) were more likely to adopt both technologies. Nonland wealth was also associated with more adoption of both technologies, but availability of uncultivated land reduced the incentive to employ the productivity-enhancing tech nologies. Researchers also measured land-tenure security: in Tawahka society, kinship ties are a more important indicator of this than are legal property rights, so researchers measured it by a household's duration of residence in its village. They found that longer residence correlated with more adoption of improved plant varieties but less adoption of chemical herbicides.
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Plan: As part of its Healthy Students Initiative, Happy Meadows Elementary School decided two years ago to raise its school lunch budget by 20 percent in order to serve healthier food to its students. Result: The nutritional quality of Happy Meadows’ school lunches is no better now than it was two years ago. Further information: the annual rate of inflation since the budget change has been below 4 percent, and all of the money budgeted for lunches has been received by the school cafeteria.

In light of the further information, which of the following, if true, would best explain the result that followed from the implementation of the plan?
Frazier and Mosteller assert that medical research could be improved by a move toward larger, simpler clinical trials of medical treatments. Currently, researchers collect far more background information on patients than is strictly required for their trials-substantially more than hospitals collect-thereby escalating costs of data collection, storage, and analysis. Although limiting information collection could increase the risk that researchers will overlook facts relevant to a study, Frazier and Mosteller contend that such risk, never entirely eliminable from research, would still be small in most studies. Only in research on entirely new treatments are new and unexpected variables likely to arise.Frazier and Mosteller propose not only that researchers limit data collection on individual patients but also that researchers enroll more patients in clinical trials, thereby obtaining a more representative sample of the total population with the disease under study.[line:20][hl:4][hl:5]Often researchers restrict study participation to patients who have no ailments besides those being studied.[/hl:5][/hl:4][/line:20] A treatment judged successful under these ideal conditions can then be evaluated under normal conditions. Broadening the range of trial participants, Frazier and Mosteller suggest, would enable researchers to evaluate a treatment's efficacy for diverse patients under various conditions and to evaluate its effectiveness for different patient subgroups. For example, the value of a treatment for a progressive disease may vary according to a patient's stage of disease. [line:32][hl:2]Patients' ages[/hl:2][/line:32] may also affect a treatment's efficacy.
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If the recruitment agency does what it is to be doing, then everyone benefits—the client gets a suitable candidate for the vacant position, the candidate is placed in a satisfying position, and the agency receives a fee commensurate to its work.
Ready4 Like many other professional wrestlers, grappler and showman Jeff Hardy began to wear neon clothing and ultraviolet body paint to make a statement.
Ready4 At the beginning of the 17th century, medical practice in England was divided between the physician, who was seen as elite and usually held a university degree, with the surgeon, who was typically hospital-trained and did an apprenticeship.
Using all the information provided, select Yes if the statement about eligibility / promotion is possible. Otherwise, select No.
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A box contains only pens, pencils, and pads. If an item is randomly selected from the box, what is the probability that the item will be either a pencil or a pad?

  1. The probability that the item will be a pad is 14.
  2. The probability that the item will be a pen is 13.
When asteroids collide, some collisions cause an asteroid to spin faster; others slow it down. If asteroids are all monoliths-single rocks-undergoing random collisions, a graph of their rotation rates should show a bell-shaped distribution with statistical "tails" of very fast and very slow rotators. If asteroids are rubble piles, however, the tail representing the very fast rotators would be missing, because any loose aggregate spinning faster than once every few hours (depending on the asteroid`s bulk density) would fly apart. Researchers have discovered that [line:12]all but five observed asteroids obey a strict limit on[/line:12] rate of rotation. The exceptions are all smaller than 200 meters in diameter, with an abrupt cutoff for asteroids larger than that.The evident conclusion-[line:16][hl:2]that asteroids larger than 200 meters across are multicomponent structures or rubble piles[/hl:2][/line:16]-agrees with recent computer modeling of collisions, which also finds a transition at that diameter. A collision can blast a large asteroid to bits, but after the collision those bits will usually move slower than their mutual [line:22][hl:4]escape velocity[/hl:4][/line:22]. Over several hours, gravity will reassemble all but the fastest pieces into a rubble pile. Because collisions among asteroids are relatively frequent, most large bodies have already suffered this fate. Conversely, most small asteroids should be monolithic, because impact fragments easily escape their feeble gravity.
Exactly when in the early modern era Native Americans began exchanging animal furs with Europeans for European-made goods is uncertain. What is fairly certain, even though they left no written evidence of having done so, is that the first Europeans to conduct such trade during the modern period were fishing crews working the waters around Newfoundland. Archaeologists had noticed that sixteenth-century Native American sites were strewn with iron bolts and metal pins. [line:11][hl:4]Only later, upon reading Nicolas Denys`s 1672 account of seventeenth-century European settlements in North America, did archaeologists realize that sixteenth-century European fishing crews had dismantled and exchanged parts of their ships for furs.[/hl:4][/line:11] By the time Europeans sailing the Atlantic coast of North America first documented the fur trade, it was apparently well underway. The first to record such trade-the captain of a Portuguese vessel sailing from Newfoundland in 1501-observed that a Native American aboard the ship wore Venetian silver earrings. Another early chronicler noted in 1524 that[line:24][hl:6] Native Americans living along the coast of what is now[/hl:6][/line:24] New England had become selective about European trade goods: they accepted only knives, fishhooks, and sharp metal. By the time Cartier sailed the Saint Lawrence River ten years later, Native Americans had traded with Europeans for more than thirty years, perhaps half a century.
Citing the fact that the real gross domestic product (GDP) per capita was higher in 1997 than ever before, some [hl:3]journalists[/hl:3] have argued that the United States economy performed ideally in 1997. However, [hl:4]the real GDP is almost always higher than ever before[/hl:4]; it falls only during recessions. One point these journalists overlooked is that in 1997, as in the twenty-four years immediately preceding it, the real GDP per capita grew nearly one-half percent a year more slowly than it had on average between 1873 and 1973. Were the 1997 economy as robust as claimed, the growth rate of real GDP per capita in 1997 would have surpassed the average growth rate of real GDP per capita between 1873 and 1973 because over fifty percent of the population worked for wages in 1997 whereas only forty percent worked for wages between 1873 and 1973. If the growth rate of labor productivity (output per hour of goods and services) in 1997 had equaled its average growth rate between 1873 and 1973 of more than two percent, then, given the proportionately larger workforce that existed in 1997, real GDP per capita in 1997 would have been higher than it actually was, since output is a major factor in GDP. However, because labor productivity grew by only one percent in 1997, real GDP per capita grew more slowly in 1997 than it had on average between 1873 and 1973.
Frazier and Mosteller assert that medical research could be improved by a move toward larger, simpler clinical trials of medical treatments. Currently, researchers collect far more background information on patients than is strictly required for their trials-substantially more than hospitals collect-thereby escalating costs of data collection, storage, and analysis. Although limiting information collection could increase the risk that researchers will overlook facts relevant to a study, Frazier and Mosteller contend that such risk, never entirely eliminable from research, would still be small in most studies. Only in research on entirely new treatments are new and unexpected variables likely to arise.Frazier and Mosteller propose not only that researchers limit data collection on individual patients but also that researchers enroll more patients in clinical trials, thereby obtaining a more representative sample of the total population with the disease under study. Often researchers restrict [hl:2][hl:4]study[/hl:4][/hl:2] participation to patients who have no ailments besides those being studied. A treatment judged successful under these ideal conditions can then be evaluated under normal conditions. Broadening the range of trial participants, Frazier and Mosteller suggest, would enable researchers to evaluate a treatment's efficacy for diverse patients under various conditions and to evaluate its effectiveness for different patient subgroups. For example, the value of a treatment for a progressive disease may vary according to a patient's stage of disease. [hl:5]Patients` ages[/hl:5] may also affect a treatment's efficacy.
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Recent research on preschoolers suggests that the more the children participate in shared story-reading, their development is faster in oral and written language.
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In some cases, two clouds may break apart from the collapsing matter that typically forms a star, then holding each other in orbit around their common center of mass as a binary star.
GMAT、gmat题库、gmat模考、gmat考满分On Days 1 through 4 of a recent week, Product X was out of stock at Retailer R. Day 1 shoppers are those shoppers who came to Retailer R on Day 1 of that week seeking Product X. For each of the first 3 days of that week, the graph shows the subsequent behavior of all Day 1 shoppers who came to Retailer R seeking Product X on that day. Shoppers at Retailer R who purchased a different item in lieu of Product X paid an average of 30% more for the item.From each drop-down menu, select the option that creates the most accurate statement based on information provided.
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The ability to adapt to high-altitude living appears to have genetic roots, since tribesmen from low altitude regions were found to experience increased difficulties breathing in mountainous regions.