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91.
92.
H. Schleicher H. Balthasar M. Knölker W. Schmidt K. Jockers 《Earth, Moon, and Planets》1994,66(1):13-17
Filtergrams of high spatial and temporal resolution were obtained in the methane band centred at 892 nm during the impact of fragment L of comet Shoemaker-Levy 9 on Jupiter. The light curve shows two maxima of an emission ball observed above the limb shortly after the impact. The second maximum was the brightest and had a short life time of about 90 seconds. During it's life, the apparent height of the emission ball declined towards the surface of Jupiter; the amount of displacement is larger than the expected effect caused by Jupiter's rotation. About half an hour after the impact, a domelike feature became visible when the location of the impact rotated into the illuminated hemisphere of Jupiter. 相似文献
93.
We present a self-consistent numerical algorithm aimed at predicting the outcomes of high-velocity impacts between asteroids (or other small bodies of the solar system), based on a set of model input parameters which can be estimated from the available experimental evidence, and including the possible gravitational reaccumulation of ejected fragments whose velocity is less than a suitably defined escape velocity. All the fragment mass distributions are modelled by truncated power laws, and a possible correlation between fragment ejection velocity and mass is taken into account in different ways, including a probabilistic one. We analyze in particular the effectiveness of the gravitational reaccumulation process in terms of different choices of the collisional parameters and the assumed relationship between fragment speed and mass. Both the transition size beyond which solid targets are likely to reaccumulate a large fraction of the fragment mass and the collision energy needed to disperse most of the fragments are sensitive functions of the assumed fragment velocity versus mass relationship. We also give some examples of how our algorithm can be applied to study the origin and collisional history of small solar system bodies, including the asteroid 951 Gaspra (recently imaged by the Galileo probe) and the asteroid families. 相似文献
94.
James D. Ford Lea Berrang-Ford Malcolm King Chris Furgal 《Global Environmental Change》2010,20(4):668-680
Climate change has been identified as potentially the biggest health threat of the 21st century. Canada in general has a well developed public health system and low burden of health which will moderate vulnerability. However, there is significant heterogeneity in health outcomes, and health inequality is particularly pronounced among Aboriginal Canadians. Intervention is needed to prevent, prepare for, and manage climate change effects on Aboriginal health but is constrained by a limited understanding of vulnerability and its determinants. Despite limited research on climate change and Aboriginal health, however, there is a well established literature on Aboriginal health outcomes, determinants, and trends in Canada; characteristics that will determine vulnerability to climate change. In this paper we systematically review this literature, using a vulnerability framework to identify the broad level factors constraining adaptive capacity and increasing sensitivity to climate change. Determinants identified include: poverty, technological capacity constraints, socio-political values and inequality, institutional capacity challenges, and information deficit. The magnitude and nature of these determinants will be distributed unevenly within and between Aboriginal populations necessitating place-based and regional level studies to examine how these broad factors will affect vulnerability at lower levels. The study also supports the need for collaboration across all sectors and levels of government, open and meaningful dialogue between policy makers, scientists, health professionals, and Aboriginal communities, and capacity building at a local level, to plan for climate change. Ultimately, however, efforts to reduce the vulnerability of Aboriginal Canadians to climate change and intervene to prevent, reduce, and manage climate-sensitive health outcomes, will fail unless the broader determinants of socio-economic and health inequality are addressed. 相似文献
95.
Breadth and depth in research on health disparities: commentary on the work of Nancy Krieger 总被引:1,自引:1,他引:0
Ellen K. Cromley 《GeoJournal》2009,74(2):115-121
Geocoding and spatial analysis of data describing populations and health events are important methods in health social science
now carried out using GIS technology. This commentary considers Nancy Krieger’s work on health disparities in light of the
various ways individuals and organizations use geocoded population and health data: analyzing spatial patterns of health and
disease including health disparities, aggregating data spatially, assessing health status of individuals based on characteristics
of aggregates, modeling neighborhood contextual factors affecting health, designing observation and intervention studies,
and delivering health interventions and services. The extent to which her work addresses each of these purposes is considered.
The strengths and limitations of the research including choice of spatial analytic units and techniques as reported in the
published work are discussed. Krieger’s work, with her colleagues, has used standard methods of spatial analysis to raise
the profile of GIS and spatial analysis in the public health community. 相似文献
96.
Robert M. Suggs William J. Cooke Ronnie J. Suggs Wesley R. Swift Nicholas Hollon 《Earth, Moon, and Planets》2008,102(1-4):293-298
NASA’s Meteoroid Environment Office has implemented a program to monitor the Moon for meteoroid impacts from the Marshall
Space Flight Center. Using off-the-shelf telescopes and video equipment, the Moon is monitored for as many as 10 nights per
month, depending on weather. Custom software automatically detects flashes which are confirmed by a second telescope, photometrically
calibrated using background stars, and published on a website for correlation with other observations. Hypervelocity impact
tests at the Ames Vertical Gun Range facility have begun to determine the luminous efficiency and ejecta characteristics.
The purpose of this research is to define the impact ejecta environment for use by lunar spacecraft designers of the Constellation
manned lunar program. The observational techniques and preliminary results will be discussed.
The U.S. Government's right to retain a non-exclusive, royalty-free license in and to any copyright is acknowledged. 相似文献
97.
陈紫云 《地质灾害与环境保护》2019,30(2):41-51
康定至炉霍公路走廊沿鲜水河活动断裂带展布,断层活动造成区域地形地质条件非常复杂:地震频发、山地灾害多发,路线方案的合理布设事关项目成败。本文通过系统地搜集、整理和分析前人成果,研究论述了区域宏观构造格架、鲜水河断裂带及活动性、山地灾害等内外动力地质作用特征及相关的重大工程地质问题,在此基础上分析了断裂活动对路线方案的影响与控制作用,提出了路线方案的宏观思路见解和地震、地质灾害的专题研究建议。为路线方案设计及行业工程技术人员提供参考。 相似文献
98.
HU Zun-fang KANG Feng-xin ZOU An-de YU Lin-song LI Yang TIAN Tong-liang KANG Gui-ling 《地下水科学与工程》2019,(4):333-339
To investigate the evolution trend of water quality in Dongping Lake after South-North Water Transfer Project operation as well as to ensure the safe usage of the water receiving areas, water samples were collected and determined before and after water delivery in different hydrological seasons. Then, comprehensive pollution index method, comprehensive nutrition state index method and health risk assessment model were utilized to evaluate the quality, nutrition, and health risk of Dongping Lake water. Results showed that the quality of Dongping Lake water still met level Ⅲ (light pollution) no matter before or after water delivery. The nutrition state was improved from light eutropher before water delivery to mesotropher after water delivery. The health risk level was reduced from high-medium before water delivery to medium level after water delivery. In summary, the operation of the eastern route of South-North Water Transfer Project is beneficial for water environment improvement of Dongping Lake. 相似文献
99.
100.
安徽省人口年龄结构特征及其社会经济影响研究 总被引:1,自引:0,他引:1
根据人口普查和抽样调查的数据资料,采用对比分析、聚类分析等研究方法分析了1953~2015年安徽省人口年龄结构时间特征、空间特征。从时间上看,安徽省人口年龄结构不断演变,少儿人口数量从不断增加转变为不断减少,劳动适龄人口比重比较稳定,人口老龄化程度不断加深,总抚养系数和少年儿童抚养系数大幅度下降,老年抚养系数上升;从空间上看,人口年龄结构存在较大地区差异。安徽省人口年龄结构对社会经济发展的影响主要表现为:① 人口老年化导致劳动生产率和经济增长速度的减缓,家庭规模小型化,并对社会养老保障和医疗卫生的挑战;② 少儿人口的不断减少影响教育资源的配置;③ 人口年龄结构的区域差异进一步加剧了安徽区域发展的不平衡性。为了尽可能地减缓人口年龄结构演变对安徽省社会经济发展的不利影响,建议采取如下措施:一是充分利用“人口红利”机遇期,加快经济发展,不断促进社会进步;二是要加强引导,因地施策;三是完善社会保障制度,努力扩大社会保障制度的覆盖面,力争全覆盖,尽量减小城乡差距;四是大力发展养老产业,探索建立满足居家养老、社区养老、机构养老等多种方式需求的政府主导、政策扶持、社会参与、市场运作的社会化养老服务体系。 相似文献