3,307 research outputs found
Defect-mediated turbulence in systems with local deterministic chaos
We show that defect-mediated turbulence can exist in media where the
underlying local dynamics is deterministically chaotic. While many of the
characteristics of defect-mediated turbulence, such as the exponential decay of
correlations and a squared Poissonian distribution for the number of defects,
are identical to those seen in oscillatory media, the fluctuations in the
number of defects differ significantly. The power spectra suggest the existence
of underlying correlations that lead to a different and non-universal scaling
structure in chaotic media.Comment: 4 pages, 5 figure
Reduction and reconstruction of stochastic differential equations via symmetries
An algorithmic method to exploit a general class of infinitesimal symmetries
for reducing stochastic differential equations is presented and a natural
definition of reconstruction, inspired by the classical reconstruction by
quadratures, is proposed. As a side result the well-known solution formula for
linear one-dimensional stochastic differential equations is obtained within
this symmetry approach. The complete procedure is applied to several examples
with both theoretical and applied relevance
Self-limited self-assembly of chiral filaments
The assembly of filamentous bundles with controlled diameters is common in
biological systems and desirable for the development of nanomaterials. We
discuss dynamical simulations and free energy calculations on patchy spheres
with chiral pair interactions that spontaneously assemble into filamentous
bundles. The chirality frustrates long-range crystal order by introducing twist
between interacting subunits. For some ranges of system parameters this
constraint leads to bundles with a finite diameter as the equilibrium state,
and in other cases frustration is relieved by the formation of defects. While
some self-limited structures can be modeled as twisted filaments arranged with
local hexagonal symmetry, other structures are surprising in their complexity.Comment: 5 pages, 5 figure
Life and Death at the Edge of a Windy Cliff
The survival probability of a particle diffusing in the two dimensional
domain near a ``windy cliff'' at is investigated. The particle dies
upon reaching the edge of the cliff. In addition to diffusion, the particle is
influenced by a steady ``wind shear'' with velocity , \ie, no average bias either toward or away from the cliff.
For this semi-infinite system, the particle survival probability decays with
time as , compared to in the absence of wind. Scaling
descriptions are developed to elucidate this behavior, as well as the survival
probability within a semi-infinite strip of finite width with particle
absorption at . The behavior in the strip geometry can be described in
terms of Taylor diffusion, an approach which accounts for the crossover to the
decay when the width of the strip diverges. Supporting numerical
simulations of our analytical results are presented.Comment: 13 pages, plain TeX, 5 figures available upon request to SR
(submitted to J. Stat. Phys.
The accuracy of interpreting key psychiatric terms by ad hoc interpreters at a South African psychiatric hospital
Objective: This study examined the competence and accuracy of ad hoc interpreters in interpreting key psychiatric terms at a South African psychiatric hospital.Method: Nine individuals were asked to translate key psychiatric terms from English to Xhosa. These translations were then back-translated by independent translators, who do not have knowledge of psychiatric terminology. These back-translations were then compared with the original English. Results: It was clear that not all the participants were fully competent in English. None had formal training in interpreting or psychiatric terminology. Not all of the participants were familiar with the psychiatric concepts that clinicians use and they often made mistakes while interpreting. Conclusion: The competency levels of interpreters are unsatisfactory to ensure the optimal delivery of mental health care. It is clear that there is a need for trained interpreters in South Africa, as the continuous use of untrained interpreters compromises the effectiveness of mental health care and could lead to adverse health outcomes.Keywords: Translation; Cultural Diversity; South Africa; Health Care Quality; Access and EvaluationAfrican Journal of Psychiatry • November 2013, 16(6
COVID-19: Clean up on IL-6
The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) represents the latest threat to global health security, and the pressure to identify effective therapeutics during this pandemic is immense. This stress has led to the use of unproven therapies with greater than minimal risk. One example is the use of IL-6 receptor antagonists. After an early report of a “cytokine storm” in patients with coronavirus disease (COVID-19), there is increased interest in anti–IL-6 therapy as a treatment option, with ill-defined criteria for use (1)
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