5,515 research outputs found

    The Individual Mandate in Perspective

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    Estimates the number and percentage of Americans who are exempt from the healthcare reform law's requirement to have insurance coverage; those who are subject to it but already have coverage; and those who are required to purchase coverage or pay a fine

    Pressuring Perdue

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    Henry Spira, a moderate among animal-rights activists, aims now at the barnyard

    The determinants of farm investment and residential construction in post-reform China

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    The objective of this paper is to clarify, on the basis of detailed farm level data derived from recent surveys,the importance of factors related to tenure security, farm size and credit availability in constraining farmers'agricultural investment. In particular, a direct measure of farmers'perceptions regarding tenure security will be utilized, as well as information on transactions in the credit market. The next section provides a description of the study areas. It is followed by a discussion of factors affecting farm investment and a description of investment patterns in the study areas. A formal model of farmers'consumption and investment decisions, and an econometric analysis are then presented and results are interpreted. The last section summarizes the paper.Environmental Economics&Policies,Economic Theory&Research,Banks&Banking Reform,International Terrorism&Counterterrorism,Agricultural Knowledge&Information Systems

    Optical guiding in meter-scale plasma waveguides

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    We demonstrate a new highly tunable technique for generating meter-scale low density plasma waveguides. Such guides can enable electron acceleration to tens of GeV in a single stage. Plasma waveguides are imprinted in hydrogen gas by optical field ionization induced by two time-separated Bessel beam pulses: The first pulse, a J_0 beam, generates the core of the waveguide, while the delayed second pulse, here a J_8 or J_16 beam, generates the waveguide cladding. We demonstrate guiding of intense laser pulses over hundreds of Rayleigh lengths with on axis plasma densities as low as N_e0=5x10^16 cm^-3

    Locomotion in Response to Shifting Climate Zones: Not So Fast

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    Although a species’ locomotor capacity is suggestive of its ability to escape global climate change, such a suggestion is not necessarily straightforward. Species vary substantially in locomotor capacity, both ontogenetically and within/among populations, and much of this variation has a genetic basis. Accordingly, locomotor capacity can and does evolve rapidly, as selection experiments demonstrate. Importantly, even though this evolution of locomotor capacity may be rapid enough to escape changing climate, genetic correlations among traits (often due to pleiotropy) are such that successful or rapid dispersers are often limited in colonization or reproductive ability, which may be viewed as a trade-off. The nuanced assessment of this variation and evolution is reviewed for well-studied models: salmon, flying versus flightless insects, rodents undergoing experimental evolution, and metapopulations of butterflies. This work reveals how integration of physiology with population biology and functional genomics can be especially informative

    Credit's effect on productivity in Chinese agriculture : a microeconomic model of disequilibrium

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    Many government programs want to provide more credit to the farm sector to increase agricultural productivity. If the marginal effect on productivity is small, those resources might be put to better use elsewhere. The authors conducted an econometric analysis of the effect of credit on output supply which recognizies that credit markets are not necessarily at equilibrium - so that credit rationing and nonborrowing are both possible. Only about 37 percent of the farmers in the study area were constrained by inadequate formal credit. Informal credit sources provided funds for specific non-agricultural activities that were not fungible. The results indicate that one additional yuan of liquidity yielded 0.235 yuan of additional gross value of output. These results suggest that for the area of China covered in the study, a good part of the short-term credit may actually be used for consumption and investment. Two conclusions are suggested for evaluating the probable effect of expanding agricultural credit. First, not all farmers, and sometimes only a minority, are constrained in their farming operations by inadequate credit. And second, greater supplies of formal credit will be diverted in part to consumption, so the likely effect on output will be smaller than what one might expect if all funds are assumed to be used productively.Banks&Banking Reform,Financial Intermediation,International Terrorism&Counterterrorism,Economic Theory&Research,Environmental Economics&Policies

    Compaction dynamics in ductile granular media

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    Ductile compaction is common in many natural systems, but the temporal evolution of such systems is rarely studied. We observe surprising oscillations in the weight measured at the bottom of a self-compacting ensemble of ductile grains. The oscillations develop during the first ten hours of the experiment, and usually persist through the length of an experiment (one week). The weight oscillations are connected to the grain--wall contacts, and are directly correlated with the observed strain evolution and the dynamics of grain--wall contacts during the compaction. Here, we present the experimental results and characteristic time constants of the system, and discuss possible reasons for the measured weight oscillations.Comment: 11 pages, 14 figure
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