1,591 research outputs found
Student Characteristics and the Workplace
As the cost of higher education rises (Gardner, 2022) many are beginning to question just how much completing a college degree helps to prepare them for the workforce (Forbes, 2017, Gerth, 2017). The purpose of this investigation is to examine the perceptions of college students on their employability including the ways in which their own characteristics may relate to these perceptions. Data collection is currently underway. Students will report their perceived employability (EmployABILITY scale, Bennet & Ananthram, 2021; and Employability Scale, Rothwell et al., 2008), demographic characteristics (age, gender, major, year in college, etc.) temperament (Adult Temperament Questionnaire, Evans & Rothbart, 2007), locus of control (Rotter, 1966), and self-regulation (Brown et al., 1999). Results and their implications will be discussed
Coming clean: understanding and mitigating optical contamination and laser induced damage in advanced LIGO
The cleanliness of optical surfaces is of great concern as the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) project transitions from installation to operation at full power. More particulates than expected were observed on and near the core optics as a result of assembly and installation work, prompting a re-evaluation of longheld contamination control practices. Even low particulate levels can potentially damage the fused silica optics and reduce overall interferometer sensitivity. These risks are mitigated from a combination of the following approaches: quantifying the extent of the contamination, identifying its sources, improving practices to reduce the generation of particulates, introducing a non-contact in-situ cleaning technique for suspended optics in air, qualifying cleanliness levels against induced damage, and developing methods for remotely measuring and cleaning suspended optics under vacuum. While significant progress has been made in understanding and mitigating contamination, and thus, protecting the optics from losses and damage, there is still more work to be done to reach ultimate performance requirements
Equilibrium Sampling From Nonequilibrium Dynamics
We present some applications of an Interacting Particle System (IPS)
methodology to the field of Molecular Dynamics. This IPS method allows several
simulations of a switched random process to keep closer to equilibrium at each
time, thanks to a selection mechanism based on the relative virtual work
induced on the system. It is therefore an efficient improvement of usual
non-equilibrium simulations, which can be used to compute canonical averages,
free energy differences, and typical transitions paths
Free energies of crystalline solids: a lattice-switch Monte Carlo method
We present a method for the direct evaluation of the difference between the
free energies of two crystalline structures, of different symmetry. The method
rests on a Monte Carlo procedure which allows one to sample along a path,
through atomic-displacement-space, leading from one structure to the other by
way of an intervening transformation that switches one set of lattice vectors
for another. The configurations of both structures can thus be sampled within a
single Monte Carlo process, and the difference between their free energies
evaluated directly from the ratio of the measured probabilities of each. The
method is used to determine the difference between the free energies of the fcc
and hcp crystalline phases of a system of hard spheres.Comment: 5 pages Revtex, 3 figure
Monte Carlo simulation and global optimization without parameters
We propose a new ensemble for Monte Carlo simulations, in which each state is
assigned a statistical weight , where is the number of states with
smaller or equal energy. This ensemble has robust ergodicity properties and
gives significant weight to the ground state, making it effective for hard
optimization problems. It can be used to find free energies at all temperatures
and picks up aspects of critical behaviour (if present) without any parameter
tuning. We test it on the travelling salesperson problem, the Edwards-Anderson
spin glass and the triangular antiferromagnet.Comment: 10 pages with 3 Postscript figures, to appear in Phys. Rev. Lett
The structure of fluid trifluoromethane and methylfluoride
We present hard X-ray and neutron diffraction measurements on the polar
fluorocarbons HCF3 and H3CF under supercritical conditions and for a range of
molecular densities spanning about a factor of ten. The Levesque-Weiss-Reatto
inversion scheme has been used to deduce the site-site potentials underlying
the measured partial pair distribution functions. The orientational
correlations between adjacent fluorocarbon molecules -- which are characterized
by quite large dipole moments but no tendency to form hydrogen bonds -- are
small compared to a highly polar system like fluid hydrogen chloride. In fact,
the orientational correlations in HCF3 and H3CF are found to be nearly as small
as those of fluid CF4, a fluorocarbon with no dipole moment.Comment: 11 pages, 9 figure
An equation-free computational approach for extracting population-level behavior from individual-based models of biological dispersal
The movement of many organisms can be described as a random walk at either or
both the individual and population level. The rules for this random walk are
based on complex biological processes and it may be difficult to develop a
tractable, quantitatively-accurate, individual-level model. However, important
problems in areas ranging from ecology to medicine involve large collections of
individuals, and a further intellectual challenge is to model population-level
behavior based on a detailed individual-level model. Because of the large
number of interacting individuals and because the individual-level model is
complex, classical direct Monte Carlo simulations can be very slow, and often
of little practical use. In this case, an equation-free approach may provide
effective methods for the analysis and simulation of individual-based models.
In this paper we analyze equation-free coarse projective integration. For
analytical purposes, we start with known partial differential equations
describing biological random walks and we study the projective integration of
these equations. In particular, we illustrate how to accelerate explicit
numerical methods for solving these equations. Then we present illustrative
kinetic Monte Carlo simulations of these random walks and show a decrease in
computational time by as much as a factor of a thousand can be obtained by
exploiting the ideas developed by analysis of the closed form PDEs. The
illustrative biological example here is chemotaxis, but it could be any random
walker which biases its movement in response to environmental cues.Comment: 30 pages, submitted to Physica
Grundstate Properties of the 3D Ising Spin Glass
We study zero--temperature properties of the 3d Edwards--Anderson Ising spin
glass on finite lattices up to size . Using multicanonical sampling we
generate large numbers of groundstate configurations in thermal equilibrium.
Finite size scaling with a zero--temperature scaling exponent describes the data well. Alternatively, a descriptions in terms of Parisi
mean field behaviour is still possible. The two scenarios give significantly
different predictions on lattices of size .Comment: LATEX 9pages,figures upon request ,SCRI-9
Multicanonical Hybrid Monte Carlo: Boosting Simulations of Compact QED
We demonstrate that substantial progress can be achieved in the study of the
phase structure of 4-dimensional compact QED by a joint use of hybrid Monte
Carlo and multicanonical algorithms, through an efficient parallel
implementation. This is borne out by the observation of considerable speedup of
tunnelling between the metastable states, close to the phase transition, on the
Wilson line. We estimate that the creation of adequate samples (with order 100
flip-flops) becomes a matter of half a year's runtime at 2 Gflops sustained
performance for lattices of size up to 24^4.Comment: 15 pages, 8 figure
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