48 research outputs found

    The dominant mode of standing Alfven waves at synchronous orbit

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    Low-frequency oscillations of the earth's magnetic field recorded by the UCLA magnetometer on board ATS-1, have been examined for the six-month interval, January-June, 1968. The initial interpretation, that these oscillations represent the second harmonic of a standing Alfven wave, has been re-examined, and it is concluded that this hypothesis must be withdrawn. Using evidence from OGO-5 and ATS-5, as well as the data from ATS-1, it is argued that the dominant mode at the synchronous orbit must be the fundamental rather than the second harmonic. From 14 instances when the oscillations of distinctly different periods occurred during the same time interval at ATS-1 it is concluded that higher harmonics can exist. The period ratio in 7 of the 14 cases corresponds to the simultaneous occurrence of the second harmonic with the fundamental, and 4 other cases could be identified as the simultaneous occurrence of the fourth harmonic with the fundamental

    Physical Acoustics

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    Contains reports on six research projects.National Science Foundation (Grant G-9330)United States Navy, Office of Naval Research (Contract Nonr-1841(42)

    Similarity of the discriminative stimulus effects of ketamine, cyclazocine, and dextrorphan in the pigeon

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    Separate groups of pigeons were trained to discriminate the IM injection of ketamine, cyclazocine, or dextrorphan from saline. Each of the training drugs and phencyclidine produced dose-related, drug-appropriate responding in each group of birds. In contrast, ethylketazocine and nalorphine generally produced responding appropriate for saline. These results indicate that common elements of discriminable effects exist among ketamine, cyclazocine, and dextrorphan, structurally dissimilar compounds that are generally considered to belong to distinct pharmacological classes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46423/1/213_2004_Article_BF00422419.pd

    Solar ultraviolet radiation and ozone depletion-driven climate change: Effects on terrestrial ecosystems

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    In this assessment we summarise advances in our knowledge of how UV-B radiation (280-315 nm), together with other climate change factors, influence terrestrial organisms and ecosystems. We identify key uncertainties and knowledge gaps that limit our ability to fully evaluate the interactive effects of ozone depletion and climate change on these systems. We also evaluate the biological consequences of the way in which stratospheric ozone depletion has contributed to climate change in the Southern Hemisphere. Since the last assessment, several new findings or insights have emerged or been strengthened. These include: (1) the increasing recognition that UV-B radiation has specific regulatory roles in plant growth and development that in turn can have beneficial consequences for plant productivity via effects on plant hardiness, enhanced plant resistance to herbivores and pathogens, and improved quality of agricultural products with subsequent implications for food security; (2) UV-B radiation together with UV-A (315-400 nm) and visible (400-700 nm) radiation are significant drivers of decomposition of plant litter in globally important arid and semi-arid ecosystems, such as grasslands and deserts. This occurs through the process of photodegradation, which has implications for nutrient cycling and carbon storage, although considerable uncertainty exists in quantifying its regional and global biogeochemical significance; (3) UV radiation can contribute to climate change via its stimulation of volatile organic compounds from plants, plant litter and soils, although the magnitude, rates and spatial patterns of these emissions remain highly uncertain at present. UV-induced release of carbon from plant litter and soils may also contribute to global warming; and (4) depletion of ozone in the Southern Hemisphere modifies climate directly via effects on seasonal weather patterns (precipitation and wind) and these in turn have been linked to changes in the growth of plants across the Southern Hemisphere. Such research has broadened our understanding of the linkages that exist between the effects of ozone depletion, UV-B radiation and climate change on terrestrial ecosystems

    Habilidades e avaliação de executivos

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    Tiger Woods and the New Racial Order

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    There is no more serviceable celebrity than Tiger Woods. He is a colour- free emblem of a new America in which racism is dead and there are no barriers to progress for any member of its citizenry – a new racial order. His success obscures the grimmer reality of contemporary America. This article examines Woods, less as a person, more as a commodity of immense utility: something that effectively advertises a society that has long struggled with the issue of racism, but has finally won. Woods functions as ambulant publicity: he studiously avoids engaging with any political or remotely sensitive issue and refuses to align him- self with any particular ethnic group. In a sense, he is what one writer has called ‘a new kind of white person’. On the evidence presented here, Woods effectively invites consumers not to challenge racism directly, but to buy commodities that externalize success and in this way avoid confronting the racism that continues to bedevil most of America’s black population
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