9,925 research outputs found
Multicanonical Simulations Step by Step
The purpose of this article is to provide a starter kit for multicanonical
simulations in statistical physics. Fortran code for the -state Potts model
in dimensions can be downloaded from the Web and this paper
describes simulation results, which are in all details reproducible by running
prepared programs. To allow for comparison with exact results, the internal
energy, the specific heat, the free energy and the entropy are calculated for
the Ising () and the Potts model. % in a temperature range
from down to sufficiently low % temperatures, such that the
groundstates are included in the sampling. Analysis programs, relying on an
all-log jackknife technique, which is suitable for handling sums of very large
numbers, are introduced to calculate our final estimators
An ERTS-1 study of coastal features on the North Carolina coast
There are no author-identified significant results in this report
Stepping into the Intersection: The Unintended Consequences of Presenting a ‘Latina Educational’ at a Feminist Health Organisation
An intersectional approach is typically applied to individuals, but this lens is also needed at the level of systems. Similar to large institutions, human service agencies may maintain racism due to established patterns of Eurocentricity. Agencies also function as entities where change can be affected. The following case study is about the process of decentering whiteness at a feminist health organisation located in an urban centre in the United States. The author, a white, non-binary woman, serving on the board of directors, offered to present a graduate paper at an agency-wide meeting. Preparations for this presentation evolved into a year-long process, during which time the agency began to grapple with the limitations of a cultural competence framework in its services for women’s and trans health.Feminist intersectionality theory is used to examine the organisation’s steps towards facing its Eurocentricity. This case study provides examples from organisational practice, during a year of racial turbulence, to explore three strategies that human service agencies commonly use to avoid confronting internal issues of race. It deconstructs past events in which staff maintained systemic racism through (1) disowning past harm, (2) suppression of criticism, and (3) deflection of responsibility through white feminine fragility.A narrative of events is analysed with the support of scholarship to explore how an intersectional approach can address gaps in the flawed implementation of a cultural competence framework. Intersectionality theory can transform ways of thinking among human service providers to promote critical analysis of racism within agency settings. This framework also shows the connection between systemic racism and the delegitimisation of individuals, an essential concept to the task of decentering whiteness within human service organisations
The Problem of the "Prebiotic and Never Born Proteins"
It has been argued that the limited set of proteins used by life as we know
it could not have arisen by the process of Darwinian selection from all
possible proteins. This probabilistic argument has a number of implicit
assumptions that may not be warranted. A variety of considerations are
presented to show that the number of amino-acid sequences that need have been
sampled during the evolution of proteins is far smaller than assumed by the
argument.Comment: 14 Pages; International Journal of Astrobiology / FirstView Article /
October 2012, pp 1
On the null-controllability of the heat equation in unbounded domains
We make two remarks about the null-controllability of the heat equation with
Dirichlet condition in unbounded domains. Firstly, we give a geometric
necessary condition (for interior null-controllability in the Euclidean
setting)which implies that one can not go infinitely far away from the control
region without tending to the boundary (if any), but also applies when the
distance to the control region is bounded. The proof builds on heat kernel
estimates. Secondly, we describe a class of null-controllable heat equations on
unbounded product domains. Elementary examples include an infinite strip in the
plane controlled from one boundary and an infinite rod controlled from an
internal infinite rod. The proof combines earlier results on compact manifolds
with a new lemma saying that the null-controllability of an abstract control
system and its null-controllability cost are not changed by taking its tensor
product with a system generated by a non-positive self-adjoint operator.Comment: References [CdMZ01, dTZ00] added, abstract modifie
Magnetic Spectrometer for the IUCF Cooler
This research was sponsored by the National Science Foundation Grant NSF PHY-931478
Probability of graphs with large spectral gap by multicanonical Monte Carlo
Graphs with large spectral gap are important in various fields such as
biology, sociology and computer science. In designing such graphs, an important
question is how the probability of graphs with large spectral gap behaves. A
method based on multicanonical Monte Carlo is introduced to quantify the
behavior of this probability, which enables us to calculate extreme tails of
the distribution. The proposed method is successfully applied to random
3-regular graphs and large deviation probability is estimated.Comment: 3pages 4figure
Surface effects in the crystallization process of elastic flexible polymers
Investigating thermodynamic properties of liquid-solid transitions of
flexible homopolymers with elastic bonds by means of multicanonical Monte Carlo
simulations, we find crystalline conformations that resemble ground-state
structures of Lennard-Jones clusters. This allows us to set up a structural
classification scheme for finite-length flexible polymers and their freezing
mechanism in analogy to atomic cluster formation. Crystals of polymers with
"magic length" turn out to be perfectly icosahedral
Effective Sampling in the Configurational Space by the Multicanonical-Multioverlap Algorithm
We propose a new generalized-ensemble algorithm, which we refer to as the
multicanonical-multioverlap algorithm. By utilizing a non-Boltzmann weight
factor, this method realizes a random walk in the multi-dimensional,
energy-overlap space and explores widely in the configurational space including
specific configurations, where the overlap of a configuration with respect to a
reference state is a measure for structural similarity. We apply the
multicanonical-multioverlap molecular dynamics method to a penta peptide,
Met-enkephalin, in vacuum as a test system. We also apply the multicanonical
and multioverlap molecular dynamics methods to this system for the purpose of
comparisons. We see that the multicanonical-multioverlap molecular dynamics
method realizes effective sampling in the configurational space including
specific configurations more than the other two methods. From the results of
the multicanonical-multioverlap molecular dynamics simulation, furthermore, we
obtain a new local-minimum state of the Met-enkephalin system.Comment: 15 pages, (Revtex4), 9 figure
The non-zero baryon number formulation of QCD
We discuss the non-zero baryon number formulation of QCD in the quenched
limit at finite temperature. This describes the thermodynamics of gluons in the
background of static quark sources. Although a sign problem remains in this
theory, our simulation results show that it can be handled quite well
numerically. The transition region gets shifted to smaller temperatures and the
transition region broadens with increasing baryon number. Although the action
is in our formulation explicitly Z(3) symmetric the Polyakov loop expectation
value becomes non-zero already in the low temperature phase and the heavy quark
potential gets screened at non-vanishing number density already this phase.Comment: LATTICE99(Finite Temperature and Density), Latex2e using espcrc2.sty,
3 pages, 7 figure
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