123,890 research outputs found
A Finite Size Scaling Study of Lattice Models in the three-dimensional Ising Universality Class
We simulate the spin-1/2 Ising model and the Blume-Capel model at various
values of the parameter D on the simple cubic lattice. We perform a finite size
scaling study of lattices of a linear size up to L=360 to obtain accurate
estimates for critical exponents. We focus on values of D, where the amplitudes
of leading corrections are small. Furthermore we employ improved observables
that have a small amplitude of the leading correction. We obtain
nu=0.63002(10), eta=0.03627(10) and omega=0.832(6). We compare our results with
those obtained from previous Monte Carlo simulations and high temperature
series expansions of lattice models, by using field theoretic methods and
experiments.Comment: 25 pages, 6 figures, typos corrected, references added, conclusions
extende
Enabling transition into higher education for students with asperger syndrome
This project report provides an insight into the lives of students with Asperger Syndrome (AS) during their transition into higher education. It details the experiences of eight students with AS. Students were interviewed multiple times at various junctures throughout their first academic year. Although they told stories of everyday disabling barriers, they also shared experiences of academic and social successes. The project was primarily focused on students with AS; however, its findings will hopefully help inform inclusive policy and practice within higher education institutions
Quantum nature of cosmological bounces
Several examples are known where quantum gravity effects resolve the
classical big bang singularity by a bounce. The most detailed analysis has
probably occurred for loop quantum cosmology of isotropic models sourced by a
free, massless scalar. Once a bounce has been realized under fairly general
conditions, the central questions are how strongly quantum it behaves, what
influence quantum effects can have on its appearance, and what quantum
space-time beyond the bounce may look like. This, then, has to be taken into
account for effective equations which describe the evolution properly and can
be used for further phenomenological investigations. Here, we provide the first
analysis with interacting matter with new effective equations valid for weak
self-interactions or small masses. They differ from the free scalar equations
by crucial terms and have an important influence on the bounce and the
space-time around it. Especially the role of squeezed states, which have often
been overlooked in this context, is highlighted. The presence of a bounce is
proven for uncorrelated states, but as squeezing is a dynamical property and
may change in time, further work is required for a general conclusion.Comment: 26 page
Universal amplitude ratios in the 3D Ising Universality Class
We compute a number of universal amplitude ratios in the three-dimensional
Ising universality class. To this end, we perform Monte Carlo simulations of
the improved Blume-Capel model on the simple cubic lattice. For example, we
obtain A_+/A_-=0.536(2) and C_+/C_-=4.713(7), where A_+- and C_+- are the
amplitudes of the specific heat and the magnetic susceptibility, respectively.
The subscripts + and - indicate the high and the low temperature phase,
respectively. We compare our results with those obtained from previous Monte
Carlo simulations, high and low temperature series expansions, field theoretic
methods and experiments.Comment: 18 pages, two figures, typos corrected, discussion on finite size
corrections extende
Confirming what we know: Understanding questionable research practices in intro physics labs
Many institutions are changing the focus of their introductory physics labs
from verifying physics content towards teaching students about the skills and
nature of science. As instruction shifts, so too will the ways students
approach and behave in the labs. In this study, we evaluated students' lab
notes from an early activity in an experimentation-focused lab course. We found
that about 30% of student groups (out of 107 groups at three institutions)
recorded questionable research practices in their lab notes, such as subjective
interpretations of results or manipulating equipment and data. The large
majority of these practices were associated with confirmatory goals, which we
suspect stem from students' prior exposure to verification labs. We propose
ways for experimentation-focused labs to better engage students in the
responsible conduct of research and authentic scientific practice.Comment: 4 pages, 4 figure
Probing Hadronic Structure with The Decay
We compute the branching ratio for and
in chiral perturbation theory and find that
both decays should be observable at CEBAF. With sufficiently low thresholds on
the invariant mass a branching ratio of may be observed
for . For the decay
mode we predict a branching ratio of . The dependence of the
M1 and E2 amplitudes on the momentum transfer will provide a useful test of
chiral perturbation theory which predicts variation over the
allowed kinematic range.Comment: 6 pages, 3 figures, UCSD/PTH 93-06, QUSTH-93-02, Duke-TH-93-4
Instabilities leading to vortex lattice formation in rotating Bose-Einstein condensates
We present a comprehensive theoretical study of vortex lattice formation in
atomic Bose-Einstein condensates confined by a rotating elliptical trap. We
consider rotating solutions of the classical hydrodynamic equations, their
response to perturbations, as well as time-dependent simulations. We
discriminate three distinct, experimentally testable, regimes of instability:
{\em ripple}, {\em interbranch}, and {\em catastrophic}. Under
symmetry-breaking perturbations these instabilities lead to lattice formation
even at zero temperature. While our results are consistent with previous
theoretical and experimental results, they shed new light on lattice formation.Comment: 5 pages, 2 figure
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