Pressure-induced Superconductivity in CaLi2

A search for superconductivity has been carried out on the hexagonal polymorph of Laves-phase CaLi2, a compound for which Feng, Ashcroft, and Hoffmann predict highly anomalous behavior under pressure. No superconductivity is observed above 1.10 K at ambient pressure. However, high-pressure ac susceptibility and electrical resistivity studies to 81 GPa reveal bulk superconductivity in CaLi2 at temperatures as high as 13 K. The normal-state resistivity shows a dramatic increase with pressure.Comment: bulk superconductivity in CaLi2 now confirme

First-Order Transition and Critical End-Point in Vortex Liquids in Layered Superconductors

We calculate various thermodynamic quantities of vortex liquids in a layered superconductor by using the nonperturbative parquet approximation method, which was previously used to study the effect of thermal fluctuations in two-dimensional vortex systems. We find there is a first-order transition between two vortex liquid phases which differ in the magnitude of their correlation lengths. As the coupling between the layers increases,the first-order transition line ends at a critical point. We discuss the possible relation between this critical end-point and the disappearance of the first-order transition which is observed in experiments on high temperature superconductors at low magnetic fields.Comment: 9 pages, 5 figure

Gauge-invariant strings in the 3d U(1)+Higgs theory

We describe how the strings, which are classical solutions of the continuum three-dimensional U(1)+Higgs theory, can be studied on the lattice. The effect of an external magnetic field is also discussed and the first results on the string free energy are presented. It is shown that the string free energy can be used as an order parameter when the scalar self-coupling is large and the transition is continuous.Comment: LATTICE98(higgs); missing author added, no changes to tex

UNCOVERING FACTORS INFLUENCING PUBLIC PERCEPTIONS OF FOOD BIOTECHNOLOGY

Significant divergence exists in public opinions about biotechnology. Although there is broad support for plant biotechnology for health benefits, opinions differ on the issue of animal genetics for pure economic benefits. While some are opposed to it, many are undecided about genetically modified foods. Considerable skepticism exists about scientists, corporations and government which have negative influence on public acceptance of food biotechnology. Consumers' personal attributes have significant influence on their views about various biotechnology issues.Research and Development/Tech Change/Emerging Technologies,

Diffractive photoproduction of opposite-charge pseudoscalar meson pairs at high energies

We calculate the cross section for diffractive photoproduction of opposite-charge pseudoscalar meson pairs $M^+M^- = \pi^+ \pi^-$, $K^+ K^-$, $D^+ D^-$ and $B^+ B^-$ in a broad range of center-of-mass energies relevant for GlueX/Hall D, FOCUS, COMPASS and HERA experiments. In the case of $\pi^+\pi^-$ production we find that the interference of the $\rho^0$ resonance and the two-pion continuum leads to a considerable deformation of the shape of $\rho^0$ in agreement with the data from the ZEUS collaboration. We also discuss the spectral shape of the $\rho^0$ as a function of the momentum transfer and the contribution of higher partial waves to the $\pi^+\pi^-$ mass spectrum. We predict a sizeable energy-dependent forward-backward asymmetry in the Gottfried-Jackson frame. For the heavy meson production we find that the cross section for diffractive production increases much slower than the one for open charm or bottom production. We discuss lower and upper limits for the cross sections for diffractive production of $D^+ D^-$ and $B^+ B^-$ pairs, which we find can be as large as 10% of the open flavor production.Comment: 14 pages, 19 figure

CONSUMER ACCEPTANCE OF FOOD BIOTECHNOLOGY: WILLINGNESS TO BUY GENETICALLY MODIFIED FOOD PRODUCTS

Biotechnology is often viewed as the defining technology for the future of food and agriculture with the potential to deliver a wide range of economic and health benefits. Public acceptance of genetically modified food products is a critical factor for this emerging technology. Using data from a national survey, this study examines public acceptance of food biotechnology by modeling consumers' willingness to buy genetically modified foods. Empirical results suggest that younger, white, male and college educated individuals are more likely to accept food biotechnology. Public confidence in scientists, corporations, as well as government has significant effects on consumer acceptance of food biotechnology. While religious views influence consumer acceptance of food biotechnology, income and social/political orientations do not have significant effects. Empirical results indicate regional differences in the acceptance of genetically modified foods.Consumer/Household Economics,

PUBLIC PERCEPTIONS OF BIOTECHNOLOGY AND ACCEPTANCE OF GENETICALLY MODIFIED FOOD

Public debate on biotechnology is embroiled in controversy over the risks and benefits associated with this emerging technology. Using data from a national survey, this study analyzes public acceptance of biotechnology in food production. Empirical results suggest that while there is general optimism about biotechnology, and support for its use in plants, public approval of its use in animals is perhaps more limited. Younger and more educated individuals are generally more supportive of biotechnology. Attitudes towards biotechnology differ substantially between males and females, and between whites and non-whites. While people's religious and social views, confidence in scientists, corporations and government have significant influence, income and regional differences do not have significant effects on public acceptance of biotechnology.Consumer/Household Economics,

One-dimensional quasi-relativistic particle in the box

Two-term Weyl-type asymptotic law for the eigenvalues of one-dimensional quasi-relativistic Hamiltonian (-h^2 c^2 d^2/dx^2 + m^2 c^4)^(1/2) + V_well(x) (the Klein-Gordon square-root operator with electrostatic potential) with the infinite square well potential V_well(x) is given: the n-th eigenvalue is equal to (n pi/2 - pi/8) h c/a + O(1/n), where 2a is the width of the potential well. Simplicity of eigenvalues is proved. Some L^2 and L^infinity properties of eigenfunctions are also studied. Eigenvalues represent energies of a `massive particle in the box' quasi-relativistic model.Comment: 40 pages, 4 figures; minor correction

Studies on the Weak Itinerant Ferromagnet SrRuO3 under High Pressure to 34 GPa

The dependence of the Curie temperature Tc on nearly hydrostatic pressure has been determined to 17.2 GPa for the weak itinerant ferromagnetic SrRuO3 in both polycrystalline and single-crystalline form. Tc is found to decrease under pressure from 162 K to 42.7 K at 17.2 GPa in nearly linear fashion at the rate dTc/dP = -6.8 K/GPa. No superconductivity was found above 4 K in the pressure range 17 to 34 GPa. Room-temperature X-ray diffraction studies to 25.3 GPa reveal no structural phase transition but indicate that the average Ru-O-Ru bond angle passes through a minimum near 15 GPa. The bulk modulus and its pressure derivative were determined to be B =192(3) GPa and B' = 5.0(3), respectively. Parallel ac susceptibility studies on polycrystalline CaRuO3 at 6 and 8 GPa pressure found no evidence for either ferromagnetism or superconductivity above 4 K