9,403 research outputs found

    The 1981 Argentina ground data collection

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    Over 600 fields in the corn, soybean and wheat growing regions of the Argentine pampa were categorized by crop or cover type and ancillary data including crop calendars, historical crop production statistics and certain cropping practices were also gathered. A summary of the field work undertaken is included along with a country overview, a chronology of field trip planning and field work events, and the field work inventory of selected sample segments. LANDSAT images were annotated and used as the field work base and several hundred ground and aerial photographs were taken. These items along with segment descriptions are presented. Meetings were held with officials of the State Secretariat of Agriculture (SEAG) and the National Commission on Space Investigations (CNIE), and their support to the program are described

    TEXAS AGRICULTURE BY CONGRESSIONAL DISTRICT: 1993-1996

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    Texas Agriculture by Congressional Districts: 1993-96 is an update of previous editions of this publication. Commodity sales by county are estimates made by county agents and, therefore, are not official. In all but 4 of 30 Texas congressional districts, production agriculture accounts for over 100millioninsales.In18ofthedistricts,farmprogramcommoditiesrepresentover100 million in sales. In 18 of the districts, farm program commodities represent over 50 million in sales.Production Economics,

    Diffusion and Transport Coefficients in Synthetic Opals

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    Opals are structures composed of the closed packing of spheres in the size range of nano-to-micro meter. They are sintered to create small necks at the points of contact. We have solved the diffusion problem in such structures. The relation between the diffusion coefficient and the termal and electrical conductivity makes possible to estimate the transport coefficients of opal structures. We estimate this changes as function of the neck size and the mean-free path of the carriers. The theory presented is also applicable to the diffusion problem in other periodic structures.Comment: Submitted to PR

    The role of science in physical natural hazard assessment : report to the UK Government by the Natural Hazard Working Group

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    Following the tragic Asian tsunami on 26 December 2004, the Prime Minister asked the Government’s Chief Scientific Adviser, Sir David King, to convene a group of experts (the Natural Hazard Working Group) to advise on the mechanisms that could and should be established for the detection and early warning of global physical natural hazards. 2. The Group was asked to examine physical hazards which have high global or regional impact and for which an appropriate early warning system could be put in place. It was also asked to consider the global natural hazard frameworks currently in place and under development and their effectiveness in using scientific evidence; to consider whether there is an existing appropriate international body to pull together the international science community to advise governments on the systems that need to be put in place, and to advise on research needed to fill current gaps in knowledge. The Group was asked to make recommendations on whether a new body was needed, or whether other arrangements would be more effective

    A z=0.9 supercluster of X-ray luminous, optically-selected, massive galaxy clusters

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    We report the discovery of a compact supercluster structure at z=0.9. The structure comprises three optically-selected clusters, all of which are detected in X-rays and spectroscopically confirmed to lie at the same redshift. The Chandra X-ray temperatures imply individual masses of ~5x10^14 Msun. The X-ray masses are consistent with those inferred from optical--X-ray scaling relations established at lower redshift. A strongly-lensed z~4 Lyman break galaxy behind one of the clusters allows a strong-lensing mass to be estimated for this cluster, which is in good agreement with the X-ray measurement. Optical spectroscopy of this cluster gives a dynamical mass in good agreement with the other independent mass estimates. The three components of the RCS2319+00 supercluster are separated from their nearest neighbor by a mere <3 Mpc in the plane of the sky and likely <10 Mpc along the line-of-sight, and we interpret this structure as the high-redshift antecedent of massive (~10^15 Msun) z~0.5 clusters such as MS0451.5-0305.Comment: ApJ Letters accepted. 5 pages in emulateapj, 3 figure

    Imaging of tumor hypoxia with [124I]IAZA in comparison with [18F]FMISO and [18F]FAZA – first small animal PET results

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    PURPOSE: This study was performed to compare the 2-nitroimidazole derivatives [124I]IAZA, [18F]FAZA and well known [18F]FMISO in visualization of tumor hypoxia in a mouse model of human cancer using small animal PET. METHODS: PET imaging of female Balb/c nude mice bearing A431 tumors on a Phillips Mosaic small animal PET scanner was performed 3 h p.i. for all three tracers. Mice injected with [124I]IAZA were scanned again after 24 h and 48 h. In addition to the mice breathing air, in the case of [18F]FAZA and [124I]IAZA a second group of mice for each tracer was kept in an atmosphere of carbogen gas (5% of CO2 + 95 % of O2; from 1 h before to 3 h after injection) to evaluate the oxygenation dependency on uptake (all experiments n = 4). After the final PET scan animals were sacrificed and biodistribution was studied. RESULTS: Mice injected with [18F]FAZA displayed significantly higher tumor-to background (T/B) ratios (5.19 +/- 0.73) compared to those injected with [18F]FMISO (3.98 +/- 0.66; P lt;0.05)or[124I]IAZA(2.06+/−0.26;Plt; 0.05) or [124I]IAZA (2.06 +/- 0.26; P lt; 0.001) 3 h p.i. Carbogen breathing mice showed lower ratios ([18F]FAZA: 4.06 +/- 0.59; [124I]IAZA: 2.02 +/- 0.36). The T/B ratios increased for [124I]IAZA with time (24 h: 3.83 +/- 0.61; 48 h: 4.20 +/- 0.80), but after these late time points the absolute whole body activity was very low, as could be seen from the biodistribution data (< 0.1 %ID/g for each investigated organ) and ratios were still lower than for [18F]FAZA 3 h p.i. Due to de-iodination uptake in thyroid was high. Biodistribution data were in good agreement with the PET results. CONCLUSIONS: [18F]FAZA showed superior biokinetics compared to [18F]FMISO and [124I]IAZA in this study. Imaging at later time points that are not possible with the short lived 18F labeled tracers resulted in no advantage for [124I]IAZA, i. e. tumor to normal tissue ratios could not be improved. © 1999 Canadian Society for Pharmaceutical Sciences

    What matters to whom and why? Understanding the importance of coastal ecosystem services in developing coastal communities

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    Coastal ecosystems support the livelihoods and wellbeing of millions of people worldwide. However, the marine and terrestrial ecosystem services that coastal ecosystems provide are particularly vulnerable to global environmental change, as are the coastal communities who directly depend on them. To navigate these changes and ensure the wellbeing of coastal communities, policy-makers must know which coastal ecosystem services matter to whom, and why. Yet, in developing coastal settings, capturing people's perceptions of the importance of ecosystem services is challenging for several reasons. Firstly, coastal ecosystem services encompass both terrestrial and marine services across multiple categories (i.e. provisioning, supporting, and cultural) that are difficult to value together. Secondly, widely used monetary valuation techniques are often inappropriate because of culturally specific attributions of value, and the intangible nature of key cultural ecosystem services. Thirdly, people within communities may hold different ecosystem services values. In this paper, we examine how people ascribe and explain the importance of a range of marine and terrestrial ecosystem services in three coastal communities in Papua New Guinea. We use a mixed-methods approach that combines a non-monetary ranking and rating assessment of multiple ecosystem services, with a socio-economic survey (N = 139) and qualitative explanations of why ecosystem services matter. We find that people uniformly ascribe the most importance to marine and terrestrial provisioning services that directly support their livelihoods and material wellbeing. However, within communities, gender, wealth, and years of formal schooling do shape some differences in how people rate ecosystem services. In addition, although cultural ecosystem services were often rated lower, people emphasized that they ranked provisioning services highly, in part, because of their contribution to cultural values like bequest. People also expressed concern about extractive ecosystem services, like fuelwood, that were perceived to be destructive, and were rated low. We contend that comprehensive ecosystem services assessments that include narratives can capture the broad importance of a range of ecosystem services, alongside relational values and normative judgements. This exploratory approach is a useful step towards understanding the complexities of ecosystem services in developing coastal settings

    Thermoelectric Figure of Merit of Strongly Correlated Superlattice Semiconductors

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    We solved the Anderson Lattice Hamiltonian to get the energy bands of a strongly correlated semiconductor by using slave boson mean field theory. The transport properties were calculated in the relaxation-time approximation,and the thermoelectric figure of merit was obtained for the strongly correlated semiconductor and its superlattice structures. We found that at room temperature ZTZT can reach nearly 2 for the quantum wire lattice structure.We believe that it is possible to find high values of thermoelectric figure of merit from strongly correlated semiconductor superlattice systems.Comment: 4 pages, 3 figure
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