On the Second Law of thermodynamics and the piston problem

The piston problem is investigated in the case where the length of the cylinder is infinite (on both sides) and the ratio $m/M$ is a very small parameter, where $m$ is the mass of one particle of the gaz and $M$ is the mass of the piston. Introducing initial conditions such that the stochastic motion of the piston remains in the average at the origin (no drift), it is shown that the time evolution of the fluids, analytically derived from Liouville equation, agrees with the Second Law of thermodynamics. We thus have a non equilibrium microscopical model whose evolution can be explicitly shown to obey the two laws of thermodynamics.Comment: 29 pages, 9 figures submitted to Journal of Statistical Physics (2003

Unique Minimal Liftings for Simplicial Polytopes

For a minimal inequality derived from a maximal lattice-free simplicial polytope in $\R^n$, we investigate the region where minimal liftings are uniquely defined, and we characterize when this region covers $\R^n$. We then use this characterization to show that a minimal inequality derived from a maximal lattice-free simplex in $\R^n$ with exactly one lattice point in the relative interior of each facet has a unique minimal lifting if and only if all the vertices of the simplex are lattice points.Comment: 15 page

The effect of new anthracycline derivatives on the induction of apoptotic processes in human neoplastic cells.

This study was an attempt to determine the effect of a selected anthracycline derivative, WP903, on apoptotic processes in human melanoma cells depending on intracellular concentrations of the compound, and to evaluate the significance of apoptosis induction for the cytotoxic effect of anthracycline antibiotics. It was found that the WP903, contrary to ADR (adriamycin) is a strong inducer of apoptotic processes in ME18 human melanoma cells regardless of their susceptibility to adriamycin and WP903. The cells were treated for 24 h with ADR (1 and 5 microg/ml) or WP903 (0.2 and 2 microg/ml). Apoptosis was detected with the use of annexin V-FITC and PI (propidium iodide) and with TUNEL assay. WP903 used at 0.2 microg/ml induced early apoptosis in 23% of ME18 cells and in 60% of ME18/R cells; at 2 microg/ml in 70% of each of cell line tested. Significant late apoptotic effect was observed in ME18 cells. In contrast, ADR was found to be a weak inducer of apoptotic events. The results suggest that apoptosis is not a mechanism directly related to the cytotoxic effect of anthracycline antibiotics

Hairy canola deters flea beetle feeding

Non-Peer ReviewedFlea beetle, chiefly Phyllotreta crucifrerae, behaviour and feeding on lines of Brassica napus canola with elevated levels of trichomes on true leaves were compared with feeding on leaves of parent seedlings. The beetles became agitated and seldom settled down to feed when exposed to the hairy seedlings. Levels of feeding on the new lines were measured in a laboratory trial at Saskatoon, and in field trials at Saskatoon (2005, 2006) and Lethbridge (2006). Initially, feeding levels were lower on cotyledons of the recombinants than on those of the parental line, possibly because of the increased angle of recombinant cotyledons relative to the soil surface. As cotyledons became more horizontal on recombinant seedlings, feeding upon them increased, but feeding on true leaves of the transgenic lines was less than on true leaves of parental lines The decreased feeding on true leaves of recombinant seedlings is a first step in developing canola resistance to the insect

Lower bound for the segregation energy in the Falicov-Kimball model

In this work, a lower bound for the ground state energy of the Falicov-Kimball model for intermediate densities is derived. The explicit derivation is important in the proof of the conjecture of segregation of the two kinds of fermions in the Falicov-Kimball model, for sufficiently large interactions. This bound is given by a bulk term, plus a term proportional to the boundary of the region devoid of classical particles. A detailed proof is presented for density n=1/2, where the coefficient 10^(-13) is obtained for the boundary term, in two dimensions. With suitable modifications the method can also be used to obtain a coefficient for all densities.Comment: 8 pages, 2 figure

Entropy-driven phase transition in a polydisperse hard-rods lattice system

We study a system of rods on the 2d square lattice, with hard-core exclusion. Each rod has a length between 2 and N. We show that, when N is sufficiently large, and for suitable fugacity, there are several distinct Gibbs states, with orientational long-range order. This is in sharp contrast with the case N=2 (the monomer-dimer model), for which Heilmann and Lieb proved absence of phase transition at any fugacity. This is the first example of a pure hard-core system with phases displaying orientational order, but not translational order; this is a fundamental characteristic feature of liquid crystals