Investigation of the anisotropy of dissipation processes in single crystal of Yba2Cu3O7-d system

By means of contactless mechanical method of the measurement of energy losses in superconductors, the anisotropy of dissipation processes has been studied in single crystal high-temperature layered superconductors of Yba2Cu3O7-d system, being in mixed state. The observed anisotropy of energy losses indicates the possibility of the existence of the symmetry of order parameter of dx2-y2 type in these single crystals.Comment: 4 pages, 3 figure

Collisions and drag in debris discs with eccentric parent belts

Context: High-resolution images of circumstellar debris discs reveal off-centred rings that indicate past or ongoing perturbation, possibly caused by secular gravitational interaction with unseen stellar or substellar companions. The purely dynamical aspects of this departure from radial symmetry are well understood. However, the observed dust is subject to additional forces and effects, most notably collisions and drag. Aims: To complement the studies of dynamics, we therefore aim to understand how new asymmetries are created by the addition of collisional evolution and drag forces, and existing ones strengthened or overridden. Methods: We augmented our existing numerical code "Analysis of Collisional Evolution" (ACE) by an azimuthal dimension, the longitude of periapse. A set of fiducial discs with global eccentricities ranging from 0 to 0.4 is evolved over giga-year timescales. Size distribution and spatial variation of dust are analysed and interpreted. The basic impact of belt eccentricity on spectral energy distributions (SEDs) and images is discussed. Results: We find features imposed on characteristic timescales. First, radiation pressure defines size cutoffs that differ between periapse and apoapse, resulting in an asymmetric halo. The differences in size distribution make the observable asymmetry of the halo depend on wavelength. Second, collisional equilibrium prefers smaller grains on the apastron side of the parent belt, reducing the effect of pericentre glow and the overall asymmetry. Third, Poynting-Robertson drag fills the region interior to an eccentric belt such that the apastron side is more tenuous. Interpretation and prediction of the appearance in scattered light is problematic when spatial and size distribution are coupled.Comment: Accepted for publication in A&A, 14 pages, 16 figure

Consumer Preferences for Animal Welfare Attributes: The Case of Gestation Crates

Animal welfare concerns are having dramatic impacts on food and livestock markets. Here we examine consumer preferences for pork products with a focus on use of gestation crates. We examine underlying consumer valuations of pork attributes while considering preference heterogeneity as well as voluntary and legislative alternatives in producing gestation crate-free pork. Our results suggest that prohibiting swine producers from using gestation crates fails to improve consumer welfare in the presence of a labeling scheme documenting voluntary disadoption of gestation crates. Consumers are found to implicitly associate animal welfare attributes with smaller farms. Preference heterogeneity drives notably diverse consumer welfare impacts when pork produced with use of gestation crates is no longer available for consumption.animal welfare, consumer welfare, economics of legislation, gestation crates, pork, swine, voluntary labeling, willingness to pay, Agribusiness, Agricultural and Food Policy, Consumer/Household Economics, Industrial Organization, Livestock Production/Industries, Q11, Q13, Q18,

Verifying Credence Attributes in Livestock Production

Livestock producers can respond to increasing consumer demand for certain production process attributes by providing verifiable information on the practices used. Consumer willingness to pay data were used to inform producer decision-making regarding selection of verification entities for four key production process attributes in the production of pork chops and milk. The potential for informing farm-level decision-making with information about consumer demand for product and production process attributes exists beyond the two products assessed as example cases in this analysis.Key Words: animal welfare, certification, credence attribute, producer decision support, response to consumer demand, verification, willingness to pay, Consumer/Household Economics, Demand and Price Analysis, Livestock Production/Industries, Production Economics, Q11, Q12, Q19,

Media Coverage of Animal Handling and Welfare: Influence on Meat Demand

Replaced with revised version of paper 7/21/09.animal welfare, consumer demand, meat quality, media information, Rotterdam model, source of information, information indices, Agricultural and Food Policy, Demand and Price Analysis,

Producer Technology Use and the Value of Autonomy: The Case of rbST

Farm Management, Production Economics, Productivity Analysis,

Consumer Willingness to Pay for Livestock Credence Attribute Claim Verification

A choice experiment was used to determine consumer value for verification of livestock production process attributes. Willingness to pay for verification of production process attributes varied for both milk and pork chops across attributes and verifying entity. Statistically significant evidence of social desirability bias was found by comparing estimates of consumer preferences solicited using direct and indirect questioning. Indirect questioning may yield more accurate representations of consumer value than direct questioning, and therefore more accurate estimates for agribusiness decision making.animal welfare, certification, consumer demand, credence attribute, social desirability bias, verification, willingness to pay, Food Consumption/Nutrition/Food Safety, Livestock Production/Industries,

Understanding U.S. Consumer Demand for Milk Production Attributes

A choice experiment was used to examine the value of various fluid milk attributes. Respondents were surveyed regarding half or whole gallon milk purchases. A split-sample design was used to examine consumer inferences regarding food safety. Willingness to pay for verification of production process attributes varied across attributes and verifying entity. Consumers were generally willing to pay substantial premiums for milk produced without the use of rbST, on local family farms, with assured food safety enhancement, and for these claims to be verified by the U.S. Department of Agriculture.milk, food safety, grazing, rbST, family farm, local, willingness to pay, Consumer/Household Economics, Food Consumption/Nutrition/Food Safety,

Supercurrent through grain boundaries in the presence of strong correlations

Strong correlations are known to severely reduce the mobility of charge carriers near half-filling and thus have an important influence on the current carrying properties of grain boundaries in the high-$T_c$ cuprates. In this work we present an extension of the Gutzwiller projection approach to treat electronic correlations below as well as above half-filling consistently. We apply this method to investigate the critical current through grain boundaries with a wide range of misalignment angles for electron- and hole-doped systems. For the latter excellent agreement with experimental data is found. We further provide a detailed comparison to an analogous weak-coupling evaluation.Comment: 4 pages, 3 figure