9,626 research outputs found
Two Stages in the evolution of binary alkali Bose-Einstein condensate mixtures towards phase segregation
Two stages of quantum spinodal decomposition is proposed and analyzed for
this highly non-equilibrium process. Both time and spatial scales for the
process are found. Qualitative agreement with existing data is found. Some
cases the agreements are quantitative. Further experimental verifications are
indicated.Comment: late
Blow up solutions for Sinh-Gordon equation with residual mass
We are concerned with the Sinh-Gordon equation in bounded domains. We construct blow up solutions with residual mass exhibiting either partial or asymmetric blow up, i.e. where both the positive and negative part of the solution blow up. This is the first result concerning residual mass for the Sinh-Gordon equation showing in particular that the concentration-compactness theory with vanishing residuals of Brezis-Merle can not be extended to this class of problems
Wave equations associated with Liouville-type problems: global existence in time and blow-up criteria
We are concerned with wave equations associated with some Liouville-type problems on compact surfaces, focusing on sinh-Gordon equation and general Toda systems. Our aim is on one side to develop the analysis for wave equations associated with the latter problems and second, to substantially refine the analysis initiated in Chanillo and Yung (Adv Math 235:187\u2013207, 2013) concerning the mean field equation. In particular, by exploiting the variational analysis recently derived for Liouville-type problems we prove global existence in time for the subcritical case and we give general blow-up criteria for the supercritical and critical case. The strategy is mainly based on fixed point arguments and improved versions of the Moser\u2013Trudinger inequality
Idealized Slab Plasma approach for the study of Warm Dense Matter
Recently, warm dense matter (WDM) has emerged as an interdisciplinary field
that draws increasing interest in plasma physics, condensed matter physics,
high pressure science, astrophysics, inertial confinement fusion, as well as
materials science under extreme conditions. To allow the study of well-defined
WDM states, we have introduced the concept of idealized-slab plasmas that can
be realized in the laboratory via (i) the isochoric heating of a solid and (ii)
the propagation of a shock wave in a solid. The application of this concept
provides new means for probing the dynamic conductivity, equation of state,
ionization and opacity. These approaches are presented here using results
derived from first-principles (density-functional type) theory, Thomas-Fermi
type theory, and numerical simulations.Comment: 37 pages, 21 figures, available, pdf file only. To appear in: Laser
and Particle beams. To appear more or less in this form in Laser and Particle
beam
Dissipative Tunneling in 2 DEG: Effect of Magnetic Field, Impurity and Temperature
We have studied the transport process in the two dimensional electron gas
(2DEG) in presence of a magnetic field and a dissipative environment at
temperature T. By means of imaginary time series functional integral method we
calculate the decay rates at finite temperature and in the presence of
dissipation. We have studied decay rates for wide range of temperatures -- from
the thermally activated region to very low temperature region where the system
decays by quantum tunneling. We have shown that dissipation and impurity helps
the tunneling. We have also shown that tunneling is strongly affected by the
magnetic field. We have demonstrated analytical results for all the cases
mentioned above.Comment: 8 pages, 2 figure
CREB activity maintains the survival of cingulate cortical pyramidal neurons in the adult mouse brain
Cyclic AMP-responsive element binding protein (CREB) activity is known to contribute to important neuronal functions, such as synaptic plasticity, learning and memory. Using a microelectroporation technique to overexpress dominant negative mutant CREB (mCREB) in the adult mouse brain, we found that overexpression of mCREB in the forebrain cortex induced neuronal degeneration. Our findings suggest that constitutively active CREB phosphorylation is important for the survival of mammalian cells in the brain
Nonequilibrium Approach to Bloch-Peierls-Berry Dynamics
We examine the Bloch-Peierls-Berry dynamics under a classical nonequilibrium
dynamical formulation. In this formulation all coordinates in phase space
formed by the position and crystal momentum space are treated on equal footing.
Explicitly demonstrations of the no (naive) Liouville theorem and of the
validity of Darboux theorem are given. The explicit equilibrium distribution
function is obtained. The similarities and differences to previous approaches
are discussed. Our results confirm the richness of the Bloch-Peierls-Berry
dynamics
Stochastic Dynamical Structure (SDS) of Nonequilibrium Processes in the Absence of Detailed Balance. III: potential function in local stochastic dynamics and in steady state of Boltzmann-Gibbs type distribution function
From a logic point of view this is the third in the series to solve the
problem of absence of detailed balance. This paper will be denoted as SDS III.
The existence of a dynamical potential with both local and global meanings in
general nonequilibrium processes has been controversial. Following an earlier
explicit construction by one of us (Ao, J. Phys. {\bf A37}, L25 '04,
arXiv:0803.4356, referred to as SDS II), in the present paper we show
rigorously its existence for a generic class of situations in physical and
biological sciences. The local dynamical meaning of this potential function is
demonstrated via a special stochastic differential equation and its global
steady-state meaning via a novel and explicit form of Fokker-Planck equation,
the zero mass limit. We also give a procedure to obtain the special stochastic
differential equation for any given Fokker-Planck equation. No detailed balance
condition is required in our demonstration. For the first time we obtain here a
formula to describe the noise induced shift in drift force comparing to the
steady state distribution, a phenomenon extensively observed in numerical
studies. The comparison to two well known stochastic integration methods, Ito
and Stratonovich, are made ready. Such comparison was made elsewhere (Ao, Phys.
Life Rev. {\bf 2} (2005) 117. q-bio/0605020).Comment: latex. 13 page
Gain Saturation in Gain-Guided Slab Waveguides with Large-Index Antiguiding
We investigate numerically and analytically the effects of gain saturation on the propagation of the fundamental mode in a gain-guided index-antiguided slab waveguide. The propagating mode adapts to gain saturation by becoming less confined, while at the same time its peak intensity increases more slowly. At steady state, both the mode shape and the power remain constant
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