6,811 research outputs found
Time-delayed feedback in neurosystems
The influence of time delay in systems of two coupled excitable neurons is
studied in the framework of the FitzHugh-Nagumo model. Time-delay can occur in
the coupling between neurons or in a self-feedback loop. The stochastic
synchronization of instantaneously coupled neurons under the influence of white
noise can be deliberately controlled by local time-delayed feedback. By
appropriate choice of the delay time synchronization can be either enhanced or
suppressed. In delay-coupled neurons, antiphase oscillations can be induced for
sufficiently large delay and coupling strength. The additional application of
time-delayed self-feedback leads to complex scenarios of synchronized in-phase
or antiphase oscillations, bursting patterns, or amplitude death.Comment: 13 pages, 13 figure
Biology, Genetics, and Environment: Underlying Factors Influencing Alcohol Metabolism.
Gene variants encoding several of the alcohol-metabolizing enzymes, alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH), are among the largest genetic associations with risk for alcohol dependence. Certain genetic variants (i.e., alleles)--particularly the ADH1B*2, ADH1B*3, ADH1C*1, and ALDH2*2 alleles--have been associated with lower rates of alcohol dependence. These alleles may lead to an accumulation of acetaldehyde during alcohol metabolism, which can result in heightened subjective and objective effects. The prevalence of these alleles differs among ethnic groups; ADH1B*2 is found frequently in northeast Asians and occasionally Caucasians, ADH1B*3 is found predominantly in people of African ancestry, ADH1C*1 varies substantially across populations, and ALDH2*2 is found almost exclusively in northeast Asians. Differences in the prevalence of these alleles may account at least in part for ethnic differences in alcohol consumption and alcohol use disorder (AUD). However, these alleles do not act in isolation to influence the risk of AUD. For example, the gene effects of ALDH2*2 and ADH1B*2 seem to interact. Moreover, other factors have been found to influence the extent to which these alleles affect a person's alcohol involvement, including developmental stage, individual characteristics (e.g., ethnicity, antisocial behavior, and behavioral undercontrol), and environmental factors (e.g., culture, religion, family environment, and childhood adversity)
Hyperon forward spin polarizability gamma0 in baryon chiral perturbation theory
We present the calculation of the hyperon forward spin polarizability gamma0
using manifestly Lorentz covariant baryon chiral perturbation theory including
the intermediate contribution of the spin 3/2 states. As at the considered
order the extraction of gamma0 is a pure prediction of chiral perturbation
theory, the obtained values are a good test for this theory. After including
explicitly the decuplet states, our SU(2) results have a very good agreement
with the experimental data and we extend our framework to SU(3) to give
predictions to the hyperons' gamma0 values. Prominent are the Sigma^- and Xi^-
baryons as their photon transition to the decuplet is forbidden in SU(3)
symmetry and therefore they are not sensitive to the explicit inclusion of the
decuplet in the theory
Sara J. Brenneis. Genre Fusion: A New Approach to History, Fiction, and Memory in Contemporary Spain. West Lafayette, Indiana: Purdue UP, 2014. viii + 241 pp.
Review of Sara J. Brenneis. Genre Fusion: A New Approach to History, Fiction, and Memory in Contemporary Spain. West Lafayette, Indiana: Purdue UP, 2014. viii + 241 pp
Dirk van Hulle. Modern Manuscripts: The Extended Mind and Creative Undoing from Darwin to Beckett and Beyond. London: Bloomsbury, 2014. xiii + 271 pp.
Review of Dirk van Hulle. Modern Manuscripts: The Extended Mind and Creative Undoing from Darwin to Beckett and Beyond. London: Bloomsbury, 2014. xiii + 271 pp
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