On Calculation of Thermal Conductivity from Einstein Relation in Equilibrium MD

In equilibrium molecular dynamics, Einstein relation can be used to calculate the thermal conductivity. This method is equivalent to Green-Kubo relation and it does not require a derivation of an analytical form for the heat current. However, it is not commonly used as Green-Kubo relationship. Its wide use is hindered by the lack of a proper definition for integrated heat current (energy moment) under periodic boundary conditions. In this paper, we developed an appropriate definition for integrated heat current to calculate thermal conductivity of solids under periodic conditions. We applied this method to solid argon and silicon based systems; compared and contrasted with the Green-Kubo approach.Comment: We updated this manuscript from second version by changing the title and abstract. This paper is submitted to J. Chem. Phy

Preliminary Results on Chemical Thinning of Apple Blossoms with Ammonium Thiosulphate, NAA, and Ethephon

Preliminary tests were carried out using ammonium thiosulphate as a chemical thinning agent for apple ('Cox's Orange Pippin' and 'Braeburn') blossoms. Ethephon and NAA (1-napthylacetic acid) were included for comparison. Whole tree sprays of 37g/l ammonium thiosulphate over-thinned 'Cox's Orange Pippin' blossoms and severely scorched blossoms, foliage, and apical meristems. Ethephon at 0.35 g/l also over-thinned, and NAA thinned to an intermediate extent when compared with the controls. When the lower concentration of 3.7 g/l ammonium thiosulphate was directly applied to stamens and styles of 'Braeburn' blossoms by brush, initial fruit set was only 30% that of untreated blossoms. When 0.35 g/I ethephon was directly applied by brush to spur leaves or petals of 'Braeburn' blossoms at pink bud, initial fruit set was only 23% that of untreated blossoms. lt is concluded that ammonium thiosulphate has the potential to thin apple blossoms. Further experiments to define optimum concentrations and spray volumes are needed

Fossil biomass preserved as graphitic carbon in a late paleoproterozoic banded iron formation metamorphosed at more than 550°C

Metamorphism is thought to destroy microfossils, partly through devolatilization and graphitization of biogenic organic matter. However, the extent to which there is a loss of molecular, elemental and isotope signatures from biomass during high-temperature metamorphism is not clearly established. We report on graphitic structures inside and coating apatite grains from the c. 1850 Ma Michigamme silicate banded iron formation from Michigan, metamorphosed above 550°C. Traces of N, S, O, H, Ca and Fe are preserved in this graphitic carbon and X-ray spectra show traces of aliphatic groups. Graphitic carbon has an expanded lattice around 3.6 Å, forms microscopic concentrically-layered and radiating polygonal flakes and has homogeneous δ13C values around −22‰, identical to bulk analyses. Graphitic carbon inside apatite is associated with nanometre-size ammoniated phyllosilicate. Precursors of these metamorphic minerals and graphitic carbon originated from ferruginous clayrich sediments with biomass. We conclude that graphite coatings and inclusions in apatite grains indicate fluid remobilization during amphibolite-facies metamorphism of precursor biomass. This new evidence fills in observational gaps of metamorphosed biomass into graphite and supports the existence of biosignatures in the highly metamorphosed iron formation from the Eoarchean Akilia Association, which dates from the beginning of the sedimentary rock record

Integration of genetic, genomic and transcriptomic information identifies putative regulators of adventitious root formation in Populus

Clustering the difference in transcriptome response of PtQTL and PdQTL genotypes. Modulated Modularity Clustering of genes displaying a similar pattern of expression differences between genotypes from the PtQTL and PdQTL categories, at all time points. (DOCX 25 kb

Pore-size dependence of the thermal conductivity of porous silicon : a phonon hydrodynamic approach

Phononhydrodynamics is used to analyze the influence of porosity and of pore size on reduction in thermal conductivity in porous silicon, with respect to crystalline silicon. The expressions predict that the thermal conductivity is lower for higher porosity and for smaller pore radius, as a consequence of phononballisticeffects. The theoretical results describe experimental data better than the assumption that they only depend on porosity

Optimized Trigger for Ultra-High-Energy Cosmic-Ray and Neutrino Observations with the Low Frequency Radio Array

When an ultra-high energy neutrino or cosmic ray strikes the Lunar surface a radio-frequency pulse is emitted. We plan to use the LOFAR radio telescope to detect these pulses. In this work we propose an efficient trigger implementation for LOFAR optimized for the observation of short radio pulses.Comment: Submitted to Nuclear Instruments and Methods in Physics Research Section

Ground State Vortex Lattice Structures in d-wave Superconductors

We show in a realistic $d_{x^{2}-y^{2}}$ symmetry gap model for a cuprate superconductor that the clean vortex lattice has discontinuous structural transitions (at and near T=0), as a function of the magnetic field $B$ along the c-axis. The transitions arise from the singular nonlocal and anisotropic susceptibility of the $d_{x^{2}-y^{2}}$ superconductor to the perturbation caused by supercurrents associated with vortices. The susceptibility, due to virtual Dirac quasiparticle-hole excitation, is calculated carefully, and leads to a ground state transition for the triangular lattice from an orientation along one of the crystal axis to one at 45$^o$ to them, i.e, along the gap zero direction. The field scale is seen to be 5 Tesla $\sim (\Delta_{0}/ta)^{2}\Phi_{0}$, where $\Delta_{0}$ is the gap maximum, $t$ is the nearest neighbour hopping, $a$ is the lattice constant, and $\Phi_{0}$ is the flux quantum. At much higher fields ($\sim 28T$) there is a discontinuous transition to a centred square structure. The source of the differences from existing calculations, and experimental observability are discussed, the latter especially in view of the very small (a few degrees $K$ per vortex) differences in the ground state energy.Comment: To be published in Phys. Rev.