13,357 research outputs found
Strong correlations generically protect d-wave superconductivity against disorder
We address the question of why strongly correlated d-wave superconductors,
such as the cuprates, prove to be surprisingly robust against the introduction
of non-magnetic impurities. We show that, very generally, both the
pair-breaking and the normal state transport scattering rates are significantly
suppressed by strong correlations effects arising in the proximity to a Mott
insulating state. We also show that the correlation-renormalized scattering
amplitude is generically enhanced in the forward direction, an effect which was
previously often ascribed to the specific scattering by charged impurities
outside the copper-oxide planes.Comment: 4+e page
Numerical methods for nonlinear Dirac equation
This paper presents a review of the current state-of-the-art of numerical
methods for nonlinear Dirac (NLD) equation. Several methods are extendedly
proposed for the (1+1)-dimensional NLD equation with the scalar and vector
self-interaction and analyzed in the way of the accuracy and the time
reversibility as well as the conservation of the discrete charge, energy and
linear momentum. Those methods are the Crank-Nicolson (CN) schemes, the
linearized CN schemes, the odd-even hopscotch scheme, the leapfrog scheme, a
semi-implicit finite difference scheme, and the exponential operator splitting
(OS) schemes. The nonlinear subproblems resulted from the OS schemes are
analytically solved by fully exploiting the local conservation laws of the NLD
equation. The effectiveness of the various numerical methods, with special
focus on the error growth and the computational cost, is illustrated on two
numerical experiments, compared to two high-order accurate Runge-Kutta
discontinuous Galerkin methods. Theoretical and numerical comparisons show that
the high-order accurate OS schemes may compete well with other numerical
schemes discussed here in terms of the accuracy and the efficiency. A
fourth-order accurate OS scheme is further applied to investigating the
interaction dynamics of the NLD solitary waves under the scalar and vector
self-interaction. The results show that the interaction dynamics of two NLD
solitary waves depend on the exponent power of the self-interaction in the NLD
equation; collapse happens after collision of two equal one-humped NLD solitary
waves under the cubic vector self-interaction in contrast to no collapse
scattering for corresponding quadric case.Comment: 39 pages, 13 figure
Dynamic Studies of Scaffold-dependent Mating Pathway in Yeast
The mating pathway in \emph{Saccharomyces cerevisiae} is one of the best
understood signal transduction pathways in eukaryotes. It transmits the mating
signal from plasma membrane into the nucleus through the G-protein coupled
receptor and the mitogen-activated protein kinase (MAPK) cascade. According to
the current understandings of the mating pathway, we construct a system of
ordinary differential equations to describe the process. Our model is
consistent with a wide range of experiments, indicating that it captures some
main characteristics of the signal transduction along the pathway.
Investigation with the model reveals that the shuttling of the scaffold protein
and the dephosphorylation of kinases involved in the MAPK cascade cooperate to
regulate the response upon pheromone induction and to help preserving the
fidelity of the mating signaling. We explored factors affecting the
dose-response curves of this pathway and found that both negative feedback and
concentrations of the proteins involved in the MAPK cascade play crucial role.
Contrary to some other MAPK systems where signaling sensitivity is being
amplified successively along the cascade, here the mating signal is transmitted
through the cascade in an almost linear fashion.Comment: 36 pages, 9 figure
Quark charge balance function and hadronization effects in relativistic heavy ion collisions
We calculate the charge balance function of the bulk quark system before
hadronization and those for the directly produced and the final hadron system
in high energy heavy ion collisions. We use the covariance coefficient to
describe the strength of the correlation between the momentum of the quark and
that of the anti-quark if they are produced in a pair and fix the parameter by
comparing the results for hadrons with the available data. We study the
hadronization effects and decay contributions by comparing the results for
hadrons with those for the bulk quark system. Our results show that while
hadronization via quark combination mechanism slightly increases the width of
the charge balance functions, it preserves the main features of these functions
such as the longitudinal boost invariance and scaling properties in rapidity
space. The influence from resonance decays on the width of the balance function
is more significant but it does not destroy its boost invariance and scaling
properties in rapidity space either. The balance functions in azimuthal
direction are also presented.Comment: 9 figure
Pairwise Operator Learning for Patch Based Single-image Super-resolution
Motivated by the fact that image patches could be inherently represented by matrices, single-image super-resolution is treated as a problem of learning regression operators in a matrix space in this paper. The regression operators that map low-resolution image patches to high-resolution image patches are generally defined by left and right multiplication operators. The pairwise operators are respectively used to extract the raw and column information of low-resolution image patches for recovering high-resolution estimations. The patch based regression algorithm possesses three favorable properties. Firstly, the proposed super-resolution algorithm is efficient during both training and testing, because image patches are treated as matrices. Secondly, the data storage requirement of the optimal pairwise operator is far less than most popular single-image super-resolution algorithms because only two small sized matrices need to be stored. Lastly, the super-resolution performance is competitive with most popular single-image super-resolution algorithms because both raw and column information of image patches is considered. Experimental results show the efficiency and effectiveness of the proposed patch-based single-image superresolution algorithm
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