273 research outputs found
Magnesium-lithium alloys developed for low temperature use
Three new magnesium-lithium alloys have been developed for application at cryogenic temperatures. These lightweight alloys have approximately doubled the tensile and yield strengths at room temperature of previously described magnesium-lithium alloys
Development of light weight magnesium alloys for low temperature applications Final summary report, Mar. 21, 1966 - Mar. 25, 1967
Fabrication of light weight aluminum alloys for cryogenic application
Development of light weight magnesium alloys for low temperature applications Annual progress report, Jun. 19, 1965 - Mar. 20, 1966
Lightweight magnesium alloys for cryogenic application
Development of Light Weight Magnesium Alloys for Low Temperature Applications Annual Progress Report, 19 Jun. 1964 - 18 Jun. 1965
Lightweight, wrought magnesium alloys for high strength and ductility and low notch sensitivity applications at cryogenic temperature
Variations in hydrological connectivity of Australian semiarid landscapes indicate abrupt changes in rainfall-use efficiency of vegetation
[1] Dryland vegetation frequently shows selfâorganized spatial patterns as mosaicâlike structures of sources (bare areas) and sinks (vegetation patches) of water runoff and sediments with variable interconnection. Good examples are banded landscapes displayed by Mulga in semiarid Australia, where the spatial organization of vegetation optimizes the redistribution and use of water (and other scarce resources) at the landscape scale. Disturbances can disrupt the spatial distribution of vegetation causing a substantial loss of water by increasing landscape hydrological connectivity and consequently, affecting ecosystem function (e.g., decreasing the rainfallâuse efficiency of the landscape). We analyze (i) connectivity trends obtained from coupled analysis of remotely sensed vegetation patterns and terrain elevations in several Mulga landscapes subjected to different levels of disturbance, and (ii) the rainfallâuse efficiency of these landscapes, exploring the relationship between rainfall and remotely sensed Normalized Difference Vegetation Index. Our analyses indicate that small reductions in the fractional cover of vegetation near a particular threshold can cause abrupt changes in ecosystem function, driven by large nonlinear increases in the length of the connected flowpaths. In addition, simulations with simple vegetationâthinning algorithms show that these nonlinear changes are especially sensitive to the type of disturbance, suggesting that the amount of alterations that an ecosystem can absorb and still remain functional largely depends on disturbance type. In fact, selective thinning of the vegetation patches from their edges can cause a higher impact on the landscape hydrological connectivity than spatially random disturbances. These results highlight surface connectivity patterns as practical indicators for monitoring landscape health
Definition of a temporal distribution index for high temporal resolution precipitation data over Peninsular Spain and the Balearic Islands: the fractal dimension; and its synoptic implications
Precipitation on the Spanish mainland and in the Balearic archipelago exhibits a high degree of spatial and temporal variability, regardless of the temporal resolution of the data considered. The fractal dimension indicates the property of self-similarity, and in the case of this study, wherein it is applied to the temporal behaviour of rainfall at a fine (10-min) resolution from a total of 48 observatories, it provides insights into its more or less convective nature. The methodology of Jenkinson & Collison which automatically classifies synoptic situations at the surface, as well as an adaptation of this methodology at 500Â hPa, was applied in order to gain insights into the synoptic implications of extreme values of the fractal dimension. The highest fractal dimension values in the study area were observed in places with precipitation that has a more random behaviour over time with generally high totals. Four different regions in which the atmospheric mechanisms giving rise to precipitation at the surface differ from the corresponding above-ground mechanisms have been identified in the study area based on the fractal dimension. In the north of the Iberian Peninsula, high fractal dimension values are linked to a lower frequency of anticyclonic situations, whereas the opposite occurs in the central region. In the Mediterranean, higher fractal dimension values are associated with a higher frequency of the anticyclonic type and a lower frequency of the advective type from the east. In the south, lower fractal dimension values indicate higher frequency with respect to the anticyclonic type from the east and lower frequency with respect to the cyclonic type
Optimum Tariffs and Exhaustible Resources: Theory and Evidence for Gasoline
Domestic consumption taxes on oil products largely differ across countries, ranging from very high subsidies to very high taxes. The empirical literature on the issue has highlighted the role of revenue-raising (Ramsey commodity taxation) and externalitycorrection (Pigovian taxation) motives for national taxation. Isolatedly, the theoretical literature on non-renewable-resource taxation has emphasized the role of the optimumtariff dimension of excise taxes which reflects countriesâ non-cooperative exercise of their market power. This paper reconciles these two strands by comprehensively addressing the issue. First, we propose a multi-country model of national taxation with oil â modeled as a polluting exhaustible resource â and some regular commodities. Domestic welfare is maximized with respect to domestic taxes under a revenue-collection constraint. The optimal domestic tax on oil consumption not only consists of a Ramsey inverse-elasticity term and of a Pigovian term, but also of an optimum-tariff component. In fact, resource exhaustibility implies a form of supply inelasticity that magnifies optimum-tariff arguments. Second, based on a multiple regression using a data set with a large number of countries, we test the power of the optimum-tariff tax component in explaining national gasoline taxes. We find strong evidence that this component plays a crucial role in countriesâ taxation of gasoline
Including the public in pandemic planning: a deliberative approach
Background: Against a background of pandemic threat posed by SARS and avian H5N1 influenza, this study used deliberative forums to elucidate informed community perspectives on aspects of pandemic planning. Methods: Two deliberative forums were carried out with members of the South Australian community. The forums were supported by a qualitative study with adults and youths, systematic reviews of the literature and the involvement of an extended group of academic experts and policy makers. The forum discussions were recorded with simultaneous transcription and analysed thematically. Results: Participants allocated scarce resources of antiviral drugs and pandemic vaccine based on a desire to preserve society function in a time of crisis. Participants were divided on the acceptability of social distancing and quarantine measures. However, should such measures be adopted, they thought that reasonable financial, household and psychological support was essential. In addition, provided such support was present, the participants, in general, were willing to impose strict sanctions on those who violated quarantine and social distancing measures. Conclusions: The recommendations from the forums suggest that the implementation of pandemic plans in a severe pandemic will be challenging, but not impossible. Implementation may be more successful if the public is engaged in pandemic planning before a pandemic, effective communication of key points is practiced before and during a pandemic and if judicious use is made of supportive measures to assist those in quarantine or affected by social isolation measures.Annette J Braunack-Mayer, Jackie M Street, Wendy A Rogers, Rodney Givney, John R Moss, Janet E Hiller, Flu Views tea
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