15,000 research outputs found
Asymmetric velocity correlations in shearing media
A model of soft frictionless disks in two dimensions at zero temperature is
simulated with a shearing dynamics to study various kinds of asymmetries in
sheared systems. We examine both single particle properties, the spatial
velocity correlation function, and a correlation function designed to separate
clockwise and counter-clockwise rotational fields from one another. Among the
rich and interesting behaviors we find that the velocity correlation along the
two different diagonals corresponding to compression and dilation,
respectively, are almost identical and, furthermore, that a feature in one of
the correlation functions is directly related to irreversible plastic events
Diffusion and Velocity Auto-Correlation in Shearing Granular Media
We perform numerical simulations to examine particle diffusion at steady
shear in a model granular material in two dimensions at the jamming density and
zero temperature. We confirm findings by others that the diffusion constant
depends on shear rate as with , and set out to
determine a relation between and other exponents that characterize the
jamming transition. We then examine the the velocity auto-correlation function,
note that it is governed by two processes with different time scales, and
identify a new fundamental exponent, , that characterizes an algebraic
decay of correlations with time
Sensor Adaptation and Development in Robots by Entropy Maximization of Sensory Data
A method is presented for adapting the sensors of a robot to the statistical structure of its current environment. This enables the robot to compress incoming sensory information and to find informational relationships between sensors. The method is applied to creating sensoritopic maps of the informational relationships of the sensors of a developing robot, where the informational distance between sensors is computed using information theory and adaptive binning. The adaptive binning method constantly estimates the probability distribution of the latest inputs to maximize the entropy in each individual sensor, while conserving the correlations between different sensors. Results from simulations and robotic experiments with visual sensors show how adaptive binning of the sensory data helps the system to discover structure not found by ordinary binning. This enables the developing perceptual system of the robot to be more adapted to the particular embodiment of the robot and the environment
Vortex glass transitions in disordered three-dimensional XY models: Simulations for several different sets of parameters
The anisotropic frustrated 3D XY model with strong disorder in the coupling
constants is studied as a model of a disordered superconductor in an applied
magnetic field. Simulations with the exchange Monte Carlo method are performed
for frustrations f=1/5 and f=1/4, corresponding to two different values of the
magnetic field along the z direction. The anisotropy is also varied. The
determination of the helicity modulus from twist histograms is discussed in
some detail and the helicity modulus is used in finite size scaling analyses of
the vortex glass transition. The general picture is that the behavior in [Phys.
Rev. Lett. 91, 077002 (2003)] is confirmed. For strong (e.g. isotropic)
coupling in the z direction the helicity modulus fails to scale and it is
argued that this is due to a too small effective randomness of such systems for
the accessible system sizes
Using shared online blogs to structure and support informal coach learning. Part 2: The participants’ view and implications for coach education
In part one of this paper, Stoszkowski and Collins (2015) showed that shared online blogs were a useful tool to structure and support the informal learning of a cohort of final year undergraduate sports coaching students. The aim of the present study was to offer insight into student coaches’ perceptions of their use and experiences of structured group blogging for reflection and learning. Twenty-three student coaches (5 females, 18 males), purposely sampled from the original study, took part in four semi-structured focus group interviews. Interview data were inductively analysed. Student coaches were generally very positive about their learning experiences and the pedagogical approach employed. This was especially apparent in terms of perceived increases in levels of reflection, knowledge acquisition and improvements in coaching practice; changes corroborated by the data presented in part one. A range of reasons emerged for these outcomes, alongside several potential limiters of engagement in shared group blogging as a learning endeavour. Whilst these findings support recent, and growing proposals to systematically incorporate Web 2.0 technologies such as blogs into coach education pedagogy, several key considerations for the process of using such tools are outlined. Finally, the implications for coach educators are discussed
DNA extraction from formalin-fixed Franciscana tissues
The present paper reports the extraction of DNA from formalin-fixed Pontoporia blainvillei tissues. Following the Vachot and Monerot (1996) protocol, fragmented DNA (300-700bp) was extracted from more than 95% of liver and muscle samples. DNA yield in liver samples was significantly higher than in muscle samples (4.574 ± 1.169mg DNA/mg versus 0.808 ± 0.297mg DNA/mg). Similar results were obtained from nine other species of cetaceans and five species of pinnipeds. It is of special interest to have a method that allows the utilisation of museum specimens not originally preserved for genetic studies,
which may include rarely available, declining or extinct species.
SPANISH: El presente trabajo reporta la extracción de ADN a partir de tejidos formolizados de Pontoporia blainvillei. Siguiendo el protocolo de Vachot y Monerot (1996) se pudo extraer ADN degradado (300-700pb) en más del 95% de las muestras de hÃgado y músculo analizadas. El rendimiento en ADN fue significativamente mayor en muestras de hÃgado que en muestras de músculo (4.574 ± 1.169mg DNA/mg tejido húmedo versus 0.808 ± 0.297mg DNA/mg tejido húmedo). Resultados similares se obtuvieron en otras nueve especies de Cetáceos y cinco de PinnÃpedos. Resulta de gran interés contar con un método que permita la utilización de especÃmenes depositados en museos y que no hayan sido originalmente colectados para estudios genéticos, incluyendo especies de difÃcil obtención, en franca declinación o extintas
Duality in Shearing Rheology Near the Athermal Jamming Transition
We consider the rheology of soft-core frictionless disks in two dimensions in
the neighborhood of the athermal jamming transition. From numerical simulations
of bidisperse, overdamped, particles, we argue that the divergence of the
viscosity below jamming is characteristic of the hard-core limit, independent
of the particular soft-core interaction. We develop a mapping from soft-core to
hard-core particles that recovers all the critical behavior found in earlier
scaling analyses. Using this mapping we derive a duality relation that gives
the exponent of the non-linear Herschel-Bulkley rheology above jamming in terms
of the exponent of the diverging viscosity below jamming.Comment: 5 pages, 4 figures. Manuscript revisions: new title, additional text
concerning connections to experiment, revised Fig. 4, other minor changes and
clarifications in text. Conclusions remain essentially unchanged. Accepted
for publication in Phys. Rev. Let
I-Sharing in Group Therapy: An Approach to Improve Client Outcomes for Depression
The psychotherapeutic process rests partly on the relationship between the therapist and the client. Improved client-clinician relationships directly correlate with improved client psychological well-being. The purpose of this research project is to examine the methods in which I-sharing can improve client-clinician relationships, particularly in group therapy settings. I-sharing, a social psychological phenomenon whereby two individuals feel connected over a shared subjective experience, presents a unique approach to improving client experiences and therefore the psychological well-being of clients in therapy. This research project will focus on the potential benefits and shortcomings of employing I-Sharing in group therapy to treat Major Depressive Disorder
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