13,343 research outputs found
Gap Symmetry an Thermal Conductivity in Nodal Superconductors
There are now many nodal superconductors in heavy fermion (HF) systems,
charge conjugated organic metals, high Tc cuprates and ruthenates. On the other
hand only few of them have a well established gap function. We present here a
study of the angular dependent thermal conductivity in the vortex state of some
of the nodal superconductors. We hope it will help to identify the nodal
directions in the gap function of UPd_2Al_3, UNi_2Al_3, UBe_13 and URu_2Si_2.Comment: 4 pages, 5 figure
Nonlinear response and scaling law in the vortex state of d-wave superconductors
We study the field dependence of the quasi-particle density of states, the
thermodynamics and the transport properties in the vortex state of d-wave
superconductors when a magnetic field is applied perpendicular to the
conducting plane, specially for the low field and the low temperature compared
to the upper critical field and transition temperature, respectively, and . Both the superfluid density and the spin
susceptibility exhibit the characteristic -field dependence, while
the nuclear spin lattice relaxation rate T and the thermal
conductivity are linear in field . With increasing temperature, these
quantities exhibit the scaling behavior in . The present theory
applies to 2D -wave superconductor as well; a possible candidate of the
superconductivity in SrRuO.Comment: 11 pages, 4 figure
Central limit theorems and diffusion approximations for multiscale Markov chain models
Ordinary differential equations obtained as limits of Markov processes appear
in many settings. They may arise by scaling large systems, or by averaging
rapidly fluctuating systems, or in systems involving multiple time-scales, by a
combination of the two. Motivated by models with multiple time-scales arising
in systems biology, we present a general approach to proving a central limit
theorem capturing the fluctuations of the original model around the
deterministic limit. The central limit theorem provides a method for deriving
an appropriate diffusion (Langevin) approximation.Comment: Published in at http://dx.doi.org/10.1214/13-AAP934 the Annals of
Applied Probability (http://www.imstat.org/aap/) by the Institute of
Mathematical Statistics (http://www.imstat.org
AN ECONOMIC ANALYSIS OF INTERNATIONAL FEED AND MALTING BARLEY MARKETS: AN ECONOMETRIC SPATIAL OLIGOPOLISTIC APPROACH
A "hybrid" spatial price equilibrium model is developed to evaluate changes in production, consumption, and trade of feed and malting barley under alternative domestic and agricultural trade policy regimes. The analysis includes the economic welfare impacts of changes in various farm subsidy programs on the United States, Canada, Australia, and European Union (EU-15) which are the four major barley exporting countries in the world. The actions of competitive U.S. grain traders under the Export Enhancement Program cause feed barley exports to be segmented into two distinct markets. A spatial equilibrium is established in which the Canadian Wheat Board and Australian marketing boards behave as oligopolists in export markets under arbitrage conditions induced by U.S. and EU-15 grain traders.Malting, Feed, Farm Subsidy, Trade Policy, Export Market, Welfare, International Relations/Trade,
Elasticity-based polymer sorting in active fluids: A Brownian dynamics study
While the dynamics of polymer chains in equilibrium media is well understood
by now, the polymer dynamics in active non-equilibrium environments can be very
different. Here we study the dynamics of polymers in a viscous medium
containing self-propelled particles in two dimensions by using Brownian
dynamics simulations. We find that the polymer center of mass exhibits a
superdiffusive motion at short to intermediate times and the motion turns
normal at long times, but with a greatly enhanced diffusivity. Interestingly,
the long time diffusivity shows a non-monotonic behavior as a function of the
chain length and stiffness. We analyze how the polymer conformation and the
accumulation of the self-propelled particles, and therefore the directed motion
of the polymer, are correlated. At the point of maximal polymer diffusivity,
the polymer has preferentially bent conformations maintained by the balance
between the chain elasticity and the propelling force generated by the active
particles. We also consider the barrier crossing dynamics of actively-driven
polymers in a double-well potential. The barrier crossing times are
demonstrated to have a peculiar non-monotonic dependence, related to that of
the diffusivity. This effect can be potentially utilized for sorting of
polymers from solutions in \textit{in vitro} experiments.Comment: 11 pages, 7 figure
Possible f-wave superconductivity in SrRuO?
Until recently it has been believed that the superconductivity in
SrRuO is described by p-wave pairing. However, both the recent specific
heat and the magnetic penetration depth measurements on the purest single
crystals of SrRuO appear to be explained more consistently in terms of
f-wave superconductivity. In order to further this hypothesis, we study
theoretically the thermodynamics and thermal conductivity of f-wave
superconductors in a planar magnetic field. We find the simple expressions for
these quantities when and , which should be
readily accessible experimentally.Comment: 6 pages, 2 figure
Low-lying excitations around a single vortex in a d-wave superconductor
A full quantum-mechanical treatment of the Bogoliubov-de Gennes equation for
a single vortex in a d-wave superconductor is presented. First, we find
low-energy states extended in four diagonal directions, which have no
counterpart in a vortex of s-wave superconductors. The four-fold symmetry is
due to 'quantum effect', which is enhanced when is small. Second,
for , a peak with a large energy gap is
found in the density of states, which is due to the formation of the lowest
bound states.Comment: 7pages, Revte
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