Liquid-Vapor Transition and Critical Behavior of The Ultrasoft Restricted Primitive Model of Polyelectrolytes : a Monte Carlo Study

We present a Monte-Carlo study of the liquid-vapor transition and the critical behavior of a model of polyelectrolytes with soft gaussian charge distributions introduced recently by Coslovich, Hansen, and Kahl [J. Chem. Phys. \textbf{134}, 244514 (2011)]. A finite size study involving four different volumes in the grand canonical ensemble yields a precise determination of the critical temperature, chemical potential, and density of the model. Attempts to determine the nature of the criticality and to obtain reliable values for the critical exponents are not conclusive.Comment: 14 pages, 4 figure

Solvation in atomic liquids: connection between Gaussian field theory and density functional theory

For the problem of molecular solvation, formulated as a liquid submitted to the external potential field created by a molecular solute of arbitrary shape dissolved in that solvent, we draw a connection between the Gaussian field theory derived by David Chandler [Phys. Rev. E, 1993, 48, 2898] and classical density functional theory. We show that Chandler's results concerning the solvation of a hard core of arbitrary shape can be recovered by either minimising a linearised HNC functional using an auxiliary Lagrange multiplier field to impose a vanishing density inside the core, or by minimising this functional directly outside the core --- indeed a simpler procedure. Those equivalent approaches are compared to two other variants of DFT, either in the HNC, or partially linearised HNC approximation, for the solvation of a Lennard-Jones solute of increasing size in a Lennard-Jones solvent. Compared to Monte-Carlo simulations, all those theories give acceptable results for the inhomogeneous solvent structure, but are completely out-of-range for the solvation free-energies. This can be fixed in DFT by adding a hard-sphere bridge correction to the HNC functional.Comment: 14 pages, 4 figure

Non destructive evaluation of absorbing materials using microwave stimulated infrared thermography

The electromagnetic wave nondestructive evaluation methods that appeared some years ago are attractive because many materials can absorb hyperfrequency energy. Nevertheless, generally the detections are achieved point by point which is highly time consuming for NDE of extended structures. We developed a global method which associates electromagnetic stimulation and a detection by an IR camera (EMIR method). For others applications, this method has been used over the past several years [1,2]. The aim of this paper is to give the first results about the possibilities of this new method for NDE

New solid phase of dipolar systems

The systems of molecules with a permanent dipole moment have solid phases with various crystal symmetries. In particular, the solid phases of the simplest of these systems, the dipolar hard sphere model, have been extensively studied in the literature. The article presents Monte Carlo simulation results which, at low temperature, point to the stability of a polarized solid phase of dipolar hard spheres with the unusual number of eleven nearest neighbors, the so-called primitive tetragonal packing or tetragonal close packing.Системи молекул з постiйним дипольним моментом мають твердi фази з кристалами рiзної симетрiї. Зокрема, твердi фази найпростiшої з таких систем, моделi дипольних твердих сфер, широко вивченi у лiтературi. В статтi представленi результати моделювання методом Монте-Карло, якi при низькiй температурi вказують на стабiльнiсть поляризованої твердої фази дипольних твердих сфер з незвичайним числом одинадцяти найближчих сусiдiв, так званої примiтивної тетрагональної упаковки або тетрагональної закритої упаковки

The effect of climate change on mountain pine beetle (Dendroctonus ponderosae Hopkins) in Western Canada

The mountain pine beetle, Dendroctonus ponderosae, (MPB) is the largest forest disturbance factor throughout its range in North America. The most recent MPB outbreak began in the 1990s and has resulted in an approximate loss of 723 million cubic meters of timber. The current global warming trends have seen global temperatures increase by approximately 1°C and are forecasted to rise by an additional 0.5-1.5°C over the preceding decades. These temperature increases are having a large impact on the MPB range, biology, and physiology. The range of MPB has expanded significantly in recent decades and is forecasted to continue to increase significantly in all directions as well as an increase in elevation. With further climate warming, there is a possibility of the MPB invading the boreal forest and using jack pine as host trees. MPB oviposition time, development, and winter survivability rates have been altered due to rising temperatures