15,976 research outputs found
U.S. NEW ENGLAND GROUNDFISH MANAGEMENT UNDER THE MAGNUSON-STEVENS FISHERY CONSERVATION AND MANAGEMENT ACT
Resource /Energy Economics and Policy,
Role of oxygen-oxygen hopping in the three-band copper-oxide model: quasiparticle weight, metal insulator and magnetic phase boundaries, gap values and optical conductivity
We investigate the effect of oxygen-oxygen hopping on the three-band
copper-oxide model relevant to high- cuprates, finding that the physics is
changed only slightly as the oxygen-oxygen hopping is varied. The location of
the metal-insulator phase boundary in the plane of interaction strength and
charge transfer energy shifts by eV or less along the charge transfer
axis, the quasiparticle weight has approximately the same magnitude and doping
dependence and the qualitative characteristics of the electron-doped and
hole-doped sides of the phase diagram do not change. The results confirm the
identification of LaCuO as a material with intermediate correlation
strength. However, the magnetic phase boundary as well as higher-energy
features of the optical spectrum are found to depend on the magnitude of the
oxygen-oxygen hopping. We compare our results to previously published one-band
and three-band model calculations.Comment: 13.5 pages, 16 figure
Control over stress induces plasticity of individual prefrontal cortical neurons: A conductance-based neural simulation
Behavioral control over stressful stimuli induces resilience to future conditions when control is lacking. The medial prefrontal cortex(mPFC) is a critically important brain region required for plasticity of stress resilience. We found that control over stress induces plasticity of the intrinsic voltage-gated conductances of pyramidal neurons in the PFC. To gain insight into the underlying biophysical mechanisms of this plasticity we used the conductance- based neural simulation software tool, NEURON, to model the increase in membrane excitability associated with resilience to stress. A ball and stick multicompartment conductance-based model was used to realistically fit passive and active data traces from prototypical pyramidal neurons in neurons in rats with control over tail shock stress and those lacking control. The results indicate that the plasticity of membrane excitability associated with control over stress can be attributed to an increase in Na+ and Ca2+ T-type conductances and an increase in the leak conductance. Using simulated dendritic synaptic inputs we observed an increase in excitatory postsynaptic summation and amplification resulting in elevated action potential output. This realistic simulation suggests that control over stress enhances the output of the PFC and offers specific testable hypotheses to guide future electrophysiological mechanistic studies in animal models of resilience and vulnerability to stress
Effects of Unstable Dark Matter on Large-Scale Structure and Constraints from Future Surveys
In this paper we explore the effect of decaying dark matter (DDM) on
large-scale structure and possible constraints from galaxy imaging surveys. DDM
models have been studied, in part, as a way to address apparent discrepancies
between the predictions of standard cold dark matter models and observations of
galactic structure. Our study is aimed at developing independent constraints on
these models. In such models, DDM decays into a less massive, stable dark
matter (SDM) particle and a significantly lighter particle. The small mass
splitting between the parent DDM and the daughter SDM provides the SDM with a
recoil or "kick" velocity vk, inducing a free-streaming suppression of matter
fluctuations. This suppression may be probed via weak lensing power spectra
measured by a number of forthcoming imaging surveys that aim primarily to
constrain dark energy. Using scales on which linear perturbation theory alone
is valid (multipoles < 300), surveys like Euclid or LSST can be sensitive to vk
> 90 km/s for lifetimes ~ 1-5 Gyr. To estimate more aggressive constraints, we
model nonlinear corrections to lensing power using a simple halo evolution
model that is in good agreement with numerical simulations. In our most
ambitious forecasts, using multipoles < 3000, we find that imaging surveys can
be sensitive to vk ~ 10 km/s for lifetimes < 10 Gyr. Lensing will provide a
particularly interesting complement to existing constraints in that they will
probe the long lifetime regime far better than contemporary techniques. A
caveat to these ambitious forecasts is that the evolution of perturbations on
nonlinear scales will need to be well calibrated by numerical simulations
before they can be realized. This work motivates the pursuit of such a
numerical simulation campaign to constrain dark matter with cosmological weak
lensing.Comment: 15 pages, 7 figures. Submitted to PR
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