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1.
Sarah Church Peter Ade James Bock Melanie Bowden John Carlstrom Ken Ganga Walter Gear James Hinderks Wayne Hu Brian Keating John Kovac Andrew Lange Eric Leitch Olivier Mallie Simon Melhuish Anthony Murphy Ben Rusholme Creidhe OSullivan Lucio Piccirillo Clem Pryke Andy Taylor Keith Thompson 《New Astronomy Reviews》2003,47(11-12):1083
QUEST on DASI is a ground-based, high-sensitivity, high-resolution (ℓmax2500) experiment designed to map CMB polarization at 100 and 150 GHz and to measure the power spectra from E-modes, B-modes from lensing of the CMB, and B-modes from primordial gravitational waves. The experiment comprises a 2.6 m Cassegrain optical system, equipped with an array of 62 polarization-sensitive bolometers (PSBs), located at the South Pole. The instrument is designed to minimize systematic effects; features include differencing of pairs of orthogonal PSBs within a single feed, a rotatable achromatic waveplate, and axisymmetric rotatable optics. In addition the South Pole location allows both repeatable and highly controlled observations. QUEST on DASI will commence operation in early 2005. 相似文献
2.
Maggie Cusack Yannicke Dauphin Jean-Pierre Cuif Murielle Salom Andy Freer Huabing Yin 《Chemical Geology》2008,253(3-4):172-179
Biominerals are natural composite materials comprising organic and inorganic components. Detailed knowledge of the nature and distribution of both components is a crucial requirement in order to advance our understanding of biomineral formation, their material properties and preservation potential as well as the interpretation of environmental data. Detailed chemical data are essential for our understanding of the nature and distribution of such components. Micro-XANES mapping at the sulphur K-edge reveals that, in the brachiopod Terebratulina retusa, the sulphate concentration is higher in the outer (primary) layer than in the calcite fibres of the secondary layer. This is co-incident with a higher magnesium concentration. In contrast, the sheaths surrounding the calcite fibres contain sulphur as thiol, confirming the presence of protein while, the sulphur within the fibres themselves, occurs as sulphate. Micro-XANES analysis of the insoluble organic extract from T. retusa indicates the presence of organic sulphate while Micro-Raman spectroscopy confirms that structurally substituted sulphate (SSS) is also present although semi-quantitative Raman spectroscopy carried out in this spectral region (wavenumbers 900–1200) indicates that the sulphate present is at the threshold of detection by Raman spectroscopy. The distribution of phosphorus in the shell of T. retusa correlates well with that of protein indicating the presence of phosphorylated proteins in the periostracum, the sheaths surrounding the calcite fibres and the interface between the primary and secondary layer. 相似文献
3.
Oxidation of CH4 provides the major source for atmospheric H2 which is removed mainly by reaction with OH. Biological activity at the Earth's surface appears to represent at most a minor sink for H2. Anthropogenic activity is a significant source for both H2 and CO in the present atmosphere and may be expected to exert a growing influence in the future. Models are presented which suggest a rise in the mixing ratio of H2 from its present value of 5.6 × 10?7 to about 1.8 × 10?6 by the year 2100. The mixing ratio of CO should grow from 9.7 × 10?8 to 2.3 × 10?7 over the same time period and there should be a rise in CH4 by about a factor of 1.5 associated with anthropogenically induced reductions in tropospheric OH. 相似文献
4.
A unique historical data set describing the 142 storms producing losses in excess of $100 million in the United States during the 1950–89 period were analyzed to describe their temporal characteristics. These weather disasters (WDs) caused $66.2 billion in losses, 76% of the nation's insured losses in this period. Disasters were most prevalent in the south, southeast, northeast, and central U.S., with few in and west of the Rockies. The incidence of WDs was high in the 1950s, low in the 1960s-early 1970s, and peaked in the 1980s. Losses due to WDs peaked in the 1950s, again in the late 1960s, and with a lesser peak after 1985. The areal extent of storm losses peaked after 1975 and was least in the 1960s. The temporal variations of the three storm measures (incidence, losses, and extent) had poor agreement, and agreed only when they peaked in the 1950s. Regionally-derived time distributions of WDs showed marked north-south differences with a U-shaped 40-year distribution in the northern half of the nation, whereas southern regions had a relatively flat trend until achieving a peak in the 1980s. The temporal distributions of hurricane-caused disasters differed regionally, with the distributions in the southern, southeastern, and northeastern U.S. each quite different. Temporal distributions of thunderstorm and winter storm-produced disasters were regionally more uniform. The national 5-year WD frequencies correlated moderately well with annual mean temperatures which explained 40% of the variability found in WDs during 1950–89. Weather disasters peaked in the relatively warm-dry 1950s and again in the warm-wet 1980s, and were least in the cool-wet 1960s and 1970s. The distribution of WDs during 1950–89 appears positively related to the temporal fluctuations in cyclonic activity. 相似文献
5.
Bob Forsyth and Andy Breen report from the RAS G Discussion Meeting at the Geological Society on 11 January 2002. Presentations came from both the solar and heliospheric communities, on the 3-D structure and dynamics of the solar corona and heliosphere and their inter-relation during the present maximum in the solar activity cycle. 相似文献
6.
我国实施“天然林保护工程”以来,林区人民积极转产分流,寻找新的就业门路和生计,为走出困境、改善生活做出了不懈的努力。为了进一步开阔视野,拓展思路,借鉴他国的经验,我们选刊了“国际森林趋势组织”的几篇关于寻找新的林区就业渠道和森林环境服务市场开发方面的研究文章,以期对我国的林业改革与建设有所启示。(注:这些文章已经“森林趋势组织”的执行主管Mivhael Jenkins先生同意译成中文在本刊刊登,本刊作了部分删节和改动。原文及参考文献请参阅森林趋势组织的网页:http://www. forest-trends. org) 相似文献
7.
Lipid distribution in a subtropical southern China stalagmite as a record of soil ecosystem response to paleoclimate change 总被引:3,自引:0,他引:3
Shucheng Xie Yi Yi Junhua Huang Chaoyong Hu Yanjun Cai Matthew Collins Andy Baker 《Quaternary Research》2003,60(3):340-347
Lipid extracts from a 61.7-cm-long subtropical stalagmite in southern China, spanning the period of ca. 10,000–21,000 yr ago as constrained by U–Th dating, were analyzed using gas chromatography–mass spectrometry. The higher plants and microorganisms in the overlying soils contribute a proportion of n-alkanes identified in the stalagmite. The occurrence of LMW (lower molecular weight) n-alkanols and n-alkan-2-ones in the stalagmite was mainly related to the soil microorganisms. We suggest that HMW (higher molecular weight) n-alkanols and n-alkan-2-ones identified in the stalagmite originate from soil organics and reflect input from contemporary vegetation. Shifts in the ratio of LMW to HMW n-alkanols or n-alkan-2-ones indicative of the variation of soil ecosystems (e.g., microbial degradation of organic matter and/or the relative abundance of soil microorganisms to higher plants) are comparable with the subtropical alkenone-SST (sea surface temperature) record of the same period. The similar trends seen in the δ13C data and the lipid parameters in this stalagmite imply that the overlying soil ecosystem response to climate might be responsible for the variation of δ13C values. 相似文献
8.
Edward A. Parson Robert W. Corell Eric J. Barron Virginia Burkett Anthony Janetos Linda Joyce Thomas R. Karl Michael C. MacCracken Jerry Melillo M. Granger Morgan David S. Schimel Thomas Wilbanks 《Climatic change》2003,57(1-2):9-42
Based on the experience of the U.S. National Assessment, we propose a program of research and analysis to advance capability for assessment of climate impacts, vulnerabilities, and adaptation options. We identify specific priorities for scientific research on the responses of ecological and socioeconomic systems to climate and other stresses; for improvement in the climatic inputs to impact assessments; and for further development of assessment methods to improve their practical utility to decision-makers. Finally, we propose a new institutional model for assessment, based principally on regional efforts that integrate observations, research, data, applications, and assessment on climate and linked environmental-change issues. The proposed program will require effective collaboration between scientists, resource managers, and other stakeholders, all of whose expertise is needed to define and prioritize key regional issues, characterize relevant uncertainties, and assess potential responses. While both scientifically and organizationally challenging, such an integrated program holds the best promise of advancing our capacity to manage resources and the economy adaptively under a changing climate. 相似文献
9.
The devolution and regionalisation of political and administrative structures following the election of New Labour in 1997 have changed the nature of the state and territorial development and governance in the UK. A regional and sub-national tier has opened up within the existing multi-layered governance system operating at the supra-national, national and local scales. This ‘new institutional space’ is increasingly open to the participation of social institutions--including trade unions--in economic and social governance. Drawing upon empirical analysis of the experience of the Northern Trade Union Congress (NTUC) in the North East region of England, the paper argues that the NTUC--in contrast to its national organisation--is beginning to engage with the emergent institutional structures but its role is inhibited by the centralised strategy and structure of the TUC nationally, its own need for upgrading, capacity building and greater financial resources and the interaction between the North East’s particular legacy of tripartite corporatism and the more pluralist modes of regional development governance emerging in the English regions. Unless such issues are addressed regional trade union centres--such as the NTUC--risk remaining relatively junior partners in the emergent regional governance structures. 相似文献
10.
Primary aragonite and high‐Mg calcite in the late Cambrian (Furongian). Potential evidence from marine carbonates in Oman
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Transient aragonite seas occurred in the early Cambrian but several models suggest the late Cambrian was a time of calcite seas. Here, evidence is presented from the Andam Group, Huqf High, Oman (Gondwana) that suggests a transient Furongian (late Cambrian) aragonite sea, characterized by the precipitation of aragonite and high‐Mg calcite ooids and aragonite isopachous, fibrous, cements. Stable carbon isotope data suggest that precipitation occurred just before and during the SPICE (Steptoean Positive Carbonate Isotope Excursion). Aragonite and high‐Mg calcite precipitation can be accounted for if mMg:Ca ratios were around 1.2 given the very high atmospheric CO2 at that time and if precipitation occurred in warm waters associated with the SPICE. This, together with reported occurrences of early Furongian aragonite ooids from various locations in North America (Laurentia), suggests that aragonite and high‐Mg calcite precipitation from seawater may have been more than just a local phenomenon. 相似文献