174 research outputs found
Magnetic Effect on Potential Barrier for Nucleosynthesis II
We investigate the impact of magnetic fields on the potential barrier between
two interacting nuclei. We addressed this by solving the Boltzmann equation and
Maxwell's theory in the presence of a magnetic field, resulting in the
determination of magnetized permittivity. Additionally, we derived the
magnetized Debye potential, which combines the conventional Debye potential
with an additional magnetic component. We then compared the Boltzmann approach
with the Debye method. Both methods consistently demonstrate that magnetic
fields increase permittivity. This enhanced permittivity leads to a reduction
in the potential barrier, consequently increasing the reaction rate for
nucleosynthesis. Furthermore, the dependence on temperature and electron
density in each approach is consistent. Our findings suggest that magnetized
plasmas, which have existed since the Big Bang, have played a crucial role in
nucleosynthesis.Comment: This manuscript is a revised version of our previous submission
titled 'Magnetic Effect on Potential Barrier. Submitte
An Alternative to Variance: Gini Deviation for Risk-averse Policy Gradient
Restricting the variance of a policy's return is a popular choice in
risk-averse Reinforcement Learning (RL) due to its clear mathematical
definition and easy interpretability. Traditional methods directly restrict the
total return variance. Recent methods restrict the per-step reward variance as
a proxy. We thoroughly examine the limitations of these variance-based methods,
such as sensitivity to numerical scale and hindering of policy learning, and
propose to use an alternative risk measure, Gini deviation, as a substitute. We
study various properties of this new risk measure and derive a policy gradient
algorithm to minimize it. Empirical evaluation in domains where risk-aversion
can be clearly defined, shows that our algorithm can mitigate the limitations
of variance-based risk measures and achieves high return with low risk in terms
of variance and Gini deviation when others fail to learn a reasonable policy
Functional cooperation of of IL-1β and RGS4 in the brachial plexus avulsion mediated brain reorganization
<p>Abstract</p> <p>Backgrounds</p> <p>There is considerable evidence that central nervous system is continuously modulated by activity, behavior and skill acquisition. This study is to examine the reorganization in cortical and subcortical regions in response to brachial plexus avulsion.</p> <p>Methods</p> <p>Adult C57BL/6 mice were divided into four groups: control, 1, 3 and 6 month of brachial plexus avulsion. IL-1β, IL-6 and RGS4 expression in cortex, brainstem and spinal cord were detected by BiostarM-140 s microarray and real-time PCR. RGS4 subcellular distribution and modulation were further analyzed by primary neuron culture and Western Blot.</p> <p>Results</p> <p>After 1, 3 and 6 months of brachial plexus avulsion, 49 (0 up, 49 down), 29 (17 up, 12 down), 13 (9 up, 4 down) genes in cerebral cortex, 40 (8 up, 32 down), 11 (7 up, 4 down), 137 (63 up, 74 down) in brainstem, 27 (14 up, 13 down), 33 (18 up, 15 down), 60 (29 up, 31 down) in spinal cord were identified. Among the regulated gene, IL-1β and IL-6 were sustainable enhanced in brain stem, while PKACβ and RGS4 were up-regulated throughout cerebral cortex, brainstem and spinal cord in 3 and 6 month of nerve injury. Intriguingly, subcellular distribution of RGS4 in above three regions was dependent on the functional correlation of PKA and IL-1β.</p> <p>Conclusion</p> <p>Data herein indicated that brachial plexus avulsion could efficiently initiate and perpetuate the brain reorganization. Network involved IL-1β and RGS4 signaling might implicate in the re-establish and strengthening of the local circuits at the cortical and subcortical levels.</p
A new study of multi-phase mass and heat transfer in natural gas hydrate reservoir with an embedded discrete fracture model
Acknowledgments The authors are grateful to the National Natural Science Foundation of China (51991365), China Geological Survey Project (No. DD20211350), and Guangdong Major Project of Basic and Applied Basic Research (No. 2020B0301030003).Peer reviewedPublisher PD
Growth of curvature perturbations for PBH formation & detectable GWs in non-minimal curvaton revisited
We revisit the growth of curvature perturbations in non-minimal curvaton
scenario with a non-trivial field metric where is an
inflaton field, and incorporate the effect from the non-uniform onset of
curvaton's oscillation in terms of an axion-like potential. The field metric
plays a central role in the enhancement of curvaton field
perturbation , serving as an effective friction term which can be
either positive or negative, depending on the shape of , namely
the first derivative . Our analysis reveals that
undergoes the superhorizon growth when the condition is
satisfied. This is analogous to the mechanism responsible for the amplification
of curvature perturbations in the context of ultra-slow-roll inflation, namely
the growing modes dominate curvature perturbations. As a case study, we examine
the impact of a Gaussian dip in and conduct a thorough
investigation of both the analytical and numerical aspects of the inflationary
dynamics.Our findings indicate that the behavior of the curvaton perturbation
during inflation is not solely determined by the depth of the dip in
. Rather, the shape of the dip also plays a significant role, a
feature that has not been previously highlighted in the literature.Utilizing
the formalism, we derive analytical expressions for both
the final curvature power spectrum and the non-linear parameter
in terms of an axion-like curvaton's potential leading to the non-uniform
curvaton's oscillation.Additionally, the resulting primordial black hole
abundance and scalar-induced gravitational waves are calculated, which provide
observational windows for PBHs.Comment: 23 pages, 9 figure
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