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221.
Delegates at the simultaneous National Astronomy Meeting, UK Solar Physics meeting and Spring MIST meeting were impressed by the warm welcome and efficient organization from the hosts, the University of Central Lancaster in Preston. The meetings were successful in terms of the number of participants and the breadth and depth of science discussed, but also in terms of the spread of that science across the media. 相似文献
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Larry R. Nittler Richard D. Starr Lucy Lim Timothy J. Mccoy Thomas H. Burbine Robert C. Reedy Jacob I. Trombka Paul Gorenstein Steven W. Squyres William V. Boynton Timothy P. Mcclanahan Jesse S. Bhangoo Pamela E. Clark Mary Ellen Murphy Rosemary Killen 《Meteoritics & planetary science》2001,36(12):1673-1695
Abstract— We report major element ratios determined for the S‐class asteroid 433 Eros using remote‐sensing x‐ray fluorescence spectroscopy with the near‐Earth asteroid rendezvous Shoemaker x‐ray spectrometer (XRS). Data analysis techniques and systematic errors are described in detail. Data acquired during five solar flares and during two extended “quiet Sun” periods are presented; these results sample a representative portion of the asteroid's surface. Although systematic uncertainties are potentially large, the most internally consistent and plausible interpretation of the data is that Eros has primitive Mg/Si, Al/Si, Ca/Si and Fe/Si ratios, closely similar to H or R chondrites. Global differentiation of the asteroid is ruled out. The S/Si ratio is much lower than that of chondrites, probably reflecting impact‐induced volatilization and/or photo‐ or ion‐induced sputtering of sulfur at the surface of the asteroid. An alternative explanation for the low S/Si ratio is that it reflects a limited degree of melting with loss of an FeS‐rich partial melt. Size‐sorting processes could lead to segregation of Fe‐Ni metal from silicates within the regolith of Eros; this could indicate that the Fe/Si ratios determined by the x‐ray spectrometer are not representative of the bulk Eros composition. 相似文献
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Given an incomplete rotation curve of a spiral galaxy, various assumptions about the Galaxy beyond the last observed point are made: (A) the force falls off as 1/r
2, (B) the mass density is zero, and (C) the mass density falls off as 1/r
3. The msss distributions obtained from each of these assumptions are all well behaved, and it is impossible to choose the correct curve from considerations of the resulting mass distributions alone. The correct mass distribution in the disk system of a galaxy cannot be deduced from an incomplete rotation curve. 相似文献
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Sharon K. Greene Mark A. Schmidt Mary Grace Stobierski Mark L. Wilson 《Journal of Geographical Systems》2005,7(1):85-99
To characterize Michigans high viral meningitis incidence rates, 8,803 cases from 1993–2001 were analyzed for standard epidemiological indices, geographic distribution, and spatio-temporal clusters. Blacks and infants were found to be high-risk groups. Annual seasonality and interannual variability in epidemic magnitude were apparent. Cases were concentrated in southern Michigan, and cumulative incidence was correlated with population density at the county level (r=0.45, p<0.001). Kulldorffs Scan test identified the occurrence of spatio-temporal clusters in Lower Michigan during July–October 1998 and 2001 (p=0.01). More extensive data on cases, laboratory isolates, sociodemographics, and environmental exposures should improve detection and enhance the effectiveness of a Space-Time Information System aimed at prevention.The authors gratefully acknowledge Dr. Duane Newton, former manager of the Virology Section, Michigan Department of Community Health Bureau of Laboratories, for his provision of data on viral isolates. We also appreciate the contributions of Drs. Leah Estberg and Dunrie Greiling for ClusterSeer support, Scott Swan for his assistance with ArcView GIS, and Dr. Edward L. Ionides for his advice on time series analysis. We are grateful to Dr. Pierre Goovaerts and two anonymous reviewers for their insightful comments on an earlier draft of this paper. This project was supported in part by a grant from the National Oceanic and Atmospheric Administrations Joint Program on Climate Variability and Human Health, a consortium including the EPA, NASA, NSF, and EPRI (NA16GP2361) to MLW. 相似文献
230.
Sue Walker 《Climatic change》2005,70(1-2):311-318
Agricultural meteorologists are concerned with many operational aspects of the effects of climate on crop production, livestock,
and natural resource management. For them to continue to make a contribution to the economy of a country they must continually
sharpen their skills and remain updated on the latest available information. Training should include a variety of skills,
including transferable skills (e.g. communication, numeracy), professional skills (including cognitive skills) and information
technology skills. Problem-based learning can be used to promote critical thinking, decision making and analytical skills.
More use should be made of computer-aided learning for agricultural meteorologists’ in-service training. In particular, the
Internet or CDs could be used to disseminate specific recently developed techniques and applications to improve the understanding
of the variability in climate and its effect on agricultural production and natural resource management. Examples that can
address the vulnerability of farmers include crop–climate matching, the use of indices, crop modelling and risk assessment
together with seasonal outlooks. A strategy needs to be formulated to address these needs and implement changes in the education
and training of agricultural meteorologists. These training needs must be constantly updated to meet the changing demands
of new technology to cope with climate change and climate variability. 相似文献