1,099 research outputs found
On the reliability of mean-field methods in polymer statistical mechanics
The reliability of the mean-field approach to polymer statistical mechanics
is investigated by comparing results from a recently developed lattice
mean-field theory (LMFT) method to statistically exact results from two
independent numerical Monte Carlo simulations for the problems of a polymer
chain moving in a spherical cavity and a polymer chain partitioning between two
confining spheres of different radii. It is shown that in some cases the
agreement between the LMFT and the simulation results is excellent, while in
others, such as the case of strongly fluctuating monomer repulsion fields, the
LMFT results agree with the simulations only qualitatively. Various
approximations of the LMFT method are systematically estimated, and the
quantitative discrepancy between the two sets of results is explained with the
diminished accuracy of the saddle-point approximation, implicit in the
mean-field method, in the case of strongly fluctuating fields.Comment: 27 pages, 9 figure
Relationships among Multicultural Educational Practices, Student Self-Efficacy, and Student Cultural Identity in the High School Setting.
The purpose of this study was to examine the relationships between multicultural educational (ME) practices, student self-efficacy, and student cultural identity in the high school English setting. Surveys were administered to first-semester college freshmen which assessed their perceptions of their high school English/literature ME experiences, self-efficacy, and current ethnic identity status, with predictions that ME would positively predict self-efficacy and identity
Identifying Appropriate Games for the Missouri S& T Introduction to Artificial Intelligence Course & Tournament
The CS 347: Introduction to Artificial Intelligence (Al) class and the following Al versus human tournaments have shown that some testing of a game should be done before it is used as an educational vehicle, such as whether it provides a fair and challenging contest in a tournament. Until now, very little work has been done to study how well a game would perform in a tournament with both human and Al players before holding the tournament itself.
This research identifies several possible ways a game can be ill-suited to this class and/or tournament from previous experience and describes and utilizes a general test schema that can be applied to any turn-based two-player game to quantify a game\u27s suitability in each of these respects
Local Simulation Algorithms for Coulomb Gases with Dynamical Dielectric Effects
We discuss the application of the local lattice technique of Maggs and
Rossetto to problems that involve the motion of objects with different
dielectric constants than the background. In these systems the simulation
method produces a spurious interaction force which causes the particles to move
in an unphysical manner. We show that this term can be removed using a variant
of a method known from high-energy physics simulations, the multiboson method,
and demonstrate the effectiveness of this corrective method on a system of
neutral particles. We then apply our method to a one-component plasma to show
the effect of the spurious interaction term on a charged system.Comment: 13 pages, 4 figure
The Sarbanes-Oxley Act of 2002: Are Stricter Internal Controls Constricting International Companies?
The Role of the Dielectric Barrier in Narrow Biological Channels: a Novel Composite Approach to Modeling Single-channel Currents
A composite continuum theory for calculating ion current through a protein channel of known structure is proposed, which incorporates information about the channel dynamics. The approach is utilized to predict current through the Gramicidin A ion channel, a narrow pore in which the applicability of conventional continuum theories is questionable. The proposed approach utilizes a modified version of Poisson-Nernst-Planck (PNP) theory, termed Potential-of-Mean-Force-Poisson-Nernst-Planck theory (PMFPNP), to compute ion currents. As in standard PNP, ion permeation is modeled as a continuum drift-diffusion process in a self-consistent electrostatic potential. In PMFPNP, however, information about the dynamic relaxation of the protein and the surrounding medium is incorporated into the model of ion permeation by including the free energy of inserting a single ion into the channel, i.e., the potential of mean force along the permeation pathway. In this way the dynamic flexibility of the channel environment is approximately accounted for. The PMF profile of the ion along the Gramicidin A channel is obtained by combining an equilibrium molecular dynamics (MD) simulation that samples dynamic protein configurations when an ion resides at a particular location in the channel with a continuum electrostatics calculation of the free energy. The diffusion coefficient of a potassium ion within the channel is also calculated using the MD trajectory. Therefore, except for a reasonable choice of dielectric constants, no direct fitting parameters enter into this model. The results of our study reveal that the channel response to the permeating ion produces significant electrostatic stabilization of the ion inside the channel. The dielectric self-energy of the ion remains essentially unchanged in the course of the MD simulation, indicating that no substantial changes in the protein geometry occur as the ion passes through it. Also, the model accounts for the experimentally observed saturation of ion current with increase of the electrolyte concentration, in contrast to the predictions of standard PNP theory
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