3,184 research outputs found
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
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