986 resultados para Agricultural machinery--United States--History
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"December 1987"--P. i.
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Reprinted 1904.
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Michael S. Henry examined the first 30 years of the AP United States History exam’s essay section. This study examined changes that have occurred over the last 20 years by classifying questions into one of six categories and found little change in the types of essays used during this timeframe.
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Hector Orr began recording entries in this commonplace book during his first year as a student at Harvard and continued writing in the volume sporadically until 1804. The entries written while he was a student, from 1789 to 1792, include themes written on the following topics: Time, Discontent, Patriotism, Virtue, Conscience, Patience, Avarice, Compassion, Mortality, Self-knowledge, Benevolence, Morning, Anger, Profanity, Bribery, Autumn and Winter, Hermitage, Conscience and Anticipation. He also wrote detailed entries about the forensic disputations in which he and his classmates participated, explaining both the affirmative and negative positions. One of these disputations involved discussion of the Stamp Act, which was then quite recent history. Orr's entries about the disputations list the names of students involved and specify their position in the argument.
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http://www.archive.org/details/historyofcatholi00sheaiala
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The Prairie Pothole Region of North America has been modified by agriculture during the past 100 yr, resulting in habitat loss, fragmentation, and degradation that have reduced the abundance and productivity of many wildlife species. The 1985 U.S. Farm Bill provided economic incentives to agriculture that are considered by many to be beneficial to nesting waterfowl and other wildlife. Canada has not experienced an equally comprehensive legislative initiative, which would seem to indicate that benefits to waterfowl in Canada should lag behind those in the United States. However, with the removal of some agricultural subsidies in Canada during the 1990s, the amount of perennial cover in the Canadian prairies increased to levels similar to those of the 1970s. Therefore, it is unclear whether and how the U.S. and Canadian prairies might differ with regard to habitat quality for nesting waterfowl. We used historical and contemporary data to compare temporal trends in duck nest success between the United States and Canada and to assess how mean nest success varied with proportion of cropland and wetland density. The data best supported models with nonlinear temporal trends that varied between the two countries and suggested that mean nest success in Canada declined from its high point in 1930s and remained below the long-term value of 0.16 until the end of the time series in 2005. Mean nest success in the United States also declined from its high point in the 1930s, but increased to above the long-term value of 0.25 during the early 2000s. Mean nest success varied negatively with proportion of cropland in both the United States and Canada. Mean nest success was positively correlated with pond density at Canadian sites, but showed only a weak association with pond density at U.S. sites. All models explained the low proportions of the variation in nest success, suggesting that unmeasured factors such as the abundance and identity of nest predators may have strong effects on nest success. Nonetheless, these results support earlier suggestions that agricultural policy that encourages permanent cover positively influences duck reproductive success. We also found that, for reasons that are not entirely clear, nest success for the same intensity of row cropping was generally higher in the United States than in Canada. Further research is required to elucidate the exact nature of the composition, size, and distribution of permanent cover that coincides with greater average nest success by dabbling ducks in the United States. In addition, the data suggest that the benefits that might accrue from increases in the amount of perennial cover in Canada would be better realized if these efforts are accompanied by strong measures to conserve wetlands.