ACS Scott: input level effects on crop and soil heavy metal and metalloid concentrations

Non-Peer ReviewedDifferent input levels, defined by a combination of tillage intensity and the application of agro-chemicals, affect the availability of heavy metals and metalloids in the soil and subsequently the absorption of heavy metals and metalloids by crops. We studied the effect of organic, high, and reduced input levels in a long-term rotation study on the concentration of 24 heavy metals and metalloids in yellow peas and hard red spring wheat. The Long-Term Agro- Ecosystem Research for the Canadian Prairie Ecozone (Alternative Cropping Systems Project) was established at the AAFC Research Farm in Scott, SK, Canada in 1994, rotating in six-year cycles. We found that selenium concentration in yellow peas and cobalt concentration in hard red spring wheat were highest under the organic input level, while cadmium levels in yellow peas were highest in the high and reduced input levels. The difference in soil heavy metal and metalloid concentration was not significant among input levels but significant between crop types

Ambivalence of the anisotropy of the vortex lattice in an anisotropic type-II superconductor

We present a geometry-based discussion of possible vortex configurations in the mixed state of anisotropic type-II superconductors. It is shown that, if energy considerations assign six nearest neighbors to each vortex, two distinct modifications of the vortex lattice are possible. It is expected that certain conditions lead to a first order phase transition from one modification of the vortex lattice to the other upon varying the external magnetic field.Comment: 3 pages, 2 figure

Surface impedance anisotropy of YBa2_2Cu3_3O6.95_{6.95} single crystals: electrodynamic basis of the measurements

An electrodynamic technique is developed for determining the components of surface impedance and complex conductivity tensors of HTSC single crystals on the basis of measured quantities of a quality factor and a resonator frequency shift. A simple formula is obtained for a geometrical factor of a crystal in the form of a plate with dimensions $b\gg a>c$ in a microwave magnetic field ${\bf H_{\omega}}\perp ab$. To obtain the c-axis complex conductivity from measurements at ${\bf H_{\omega}}\parallel ab$ we propose a procedure which takes account of sample size effects. With the aid of the technique involved temperature dependences of all impedance and conductivity tensors components of YBa$_2$Cu$_3$O$_{6.95}$ single crystal, grown in BaZrO$_3$ crucible, are determined at a frequency of $f=9.4$ GHz in its normal and superconducting states. All of them proved to be linear at $T<T_c/2$, and their extrapolation to zero temperature gives the values of residual surface resistance $R_{ab}(0)\approx 40$ $\mu\Omega$ and $R_c(0)\approx 0.8$ m$\Omega$ and magnetic field penetration depth $\lambda_{ab}(0)\approx 150$ nm and $\lambda_c(0)\approx 1.55$ $\mu$m.Comment: 9 pages, 7 figures. Submitted to Phys.Rev.B 05Jun2002; accepted for publication 21Febr200

Specific heat and thermal conductivity in the vortex state of the two-gap superconductor MgB_2

The specific heat coefficient gamma_s(H) and the electronic thermal conductivity kappa_{es}(H) are calculated for Abrikosov's vortex lattice by taking into account the effects of supercurrent flow and Andreev scattering. First we solve the gap equation for the entire range of magnetic fields. We take into account vertex corrections due to impurity scattering calculated in the Born approximation. The function gamma_s(H)/gamma_n increases from zero and becomes approximately linear above H/H_{c2} \sim 0.1. The dependence on impurity scattering is substantially reduced by the vertex corrections. The upward curvature of kappa_{es}(H)/kappa_{en}, which is caused by decreasing Andreev scattering for increasing field, is reduced for increasing impurity scattering. We also calculate the temperature dependence of the scattering rates 1/tau_{ps}(H) of a phonon and 1/tau_{es}(H) of a quasiparticle due to quasiparticle and phonon scattering, respectively. At low temperatures the ratio tau_{pn}/tau_{ps}(H) increases rapidly to one as H tends to H_{c2} which yields a rapid drop in the phononic thermal conductivity kappa_{ph}. Our results are in qualitative agreement with the experiments on the two-gap superconductor MgB_2.Comment: 12 pages, 5 figures, additions to figures 1, 2, and 3. Accepted by Phys. Rev.

Classical transport equation in non-commutative QED at high temperature

We show that the high temperature behavior of non-commutative QED may be simply obtained from Boltzmann transport equations for classical particles. The transport equation for the charge neutral particle is shown to be characteristically different from that for the charged particle. These equations correctly generate, for arbitrary values of the non-commutative parameter theta, the leading, gauge independent hard thermal loops, arising from the fermion and the gauge sectors. We briefly discuss the generating functional of hard thermal amplitudes.Comment: 11 page

Non-commutative Oscillators and the commutative limit

It is shown in first order perturbation theory that anharmonic oscillators in non-commutative space behave smoothly in the commutative limit just as harmonic oscillators do. The non-commutativity provides a method for converting a problem in degenerate perturbation theory to a non-degenerate problem.Comment: Latex, 6 pages, Minor changes and references adde

The source effect: Person descriptions by self versus others have differential effects on impression formation

Contains fulltext : 77260.pdf (publisher's version ) (Closed access)Self-presentation via favorable self-descriptions may not lead to the desired impression, whereas positive descriptions by others may be more effective because they seem less susceptible to motivated bias. In four experiments, we investigated whether person descriptions have more impact on impressions when provided by third parties than by targets themselves. Results showed that target impressions were consistently more in line with the target description when positive sociability-related or positive competency-related information was given by a third party than by the target. This source effect always occurred for ratings of claimed traits. In addition, ratings of the target's sociability were also affected when the claim was about competency. Source effects were not obtained for negative self-descriptions. The results are discussed in terms of the presumed underlying process on the basis of mediation data.13 p

Impact of crop management systems on Fusarium populations in spring wheat and barley on the Canadian prairies

Non-Peer Reviewe

Transport equation for the photon Wigner operator in non-commutative QED

We derive an exact quantum equation of motion for the photon Wigner operator in non-commutative QED, which is gauge covariant. In the classical approximation, this reduces to a simple transport equation which describes the hard thermal effects in this theory. As an example of the effectiveness of this method we show that, to leading order, this equation generates in a direct way the Green amplitudes calculated perturbatively in quantum field theory at high temperature.Comment: 13 pages, twocolumn revtex4 styl

Noncommutative massive Thirring model in three-dimensional spacetime

We evaluate the noncommutative Chern-Simons action induced by fermions interacting with an Abelian gauge field in a noncommutative massive Thirring model in (2+1)-dimensional spacetime. This calculation is performed in the Dirac and Majorana representations. We observe that in Majorana representation when $\theta$ goes to zero we do not have induced Chern-Simons term in the dimensional regularization scheme.Comment: Accepted to Phys. Rev. D; 9 pages, Revtex4, no figures, references added, minor improvements, Eq.31 correcte