19 research outputs found
Vortex Core Structure and Dynamics in Layered Superconductors
We investigate the equilibrium and nonequilibrium properties of the core
region of vortices in layered superconductors. We discuss the electronic
structure of singly and doubly quantized vortices for both s-wave and d-wave
pairing symmetry. We consider the intermediate clean regime, where the
vortex-core bound states are broadened into resonances with a width comparable
to or larger than the quantized energy level spacing, and calculate the
response of a vortex core to an {\em a.c.} electromagnetic field for vortices
that are pinned to a metallic defect. We concentrate on the case where the
vortex motion is nonstationary and can be treated by linear response theory.
The response of the order parameter, impurity self energy, induced fields and
currents are obtained by a self-consistent calculation of the distribution
functions and the excitation spectrum. We then obtain the dynamical
conductivity, spatially resolved in the region of the core, for external
frequencies in the range, 0.1\Delta < \hbar\omega \lsim 3\Delta. We also
calculate the dynamically induced charge distribution in the vicinity of the
core. This charge density is related to the nonequilibrium response of the
bound states and collective mode, and dominates the electromagnetic response of
the vortex core.Comment: Presented at the 2000 Workshop on ``Microscopic Structure and
Dynamics of Vortices in Unconventional Superconductors and Superfluids'',
held at the Max Planck Institute for the Physics of Complex Systems in
Dresden, Germany (28 pages with 15 figures). Alternate version with higher
resolution figures:
http://snowmass.phys.nwu.edu/~sauls/Eprints/Dresden2000.htm
Chern-Simons theory on L(p,q) lens spaces and Gopakumar-Vafa duality
We consider aspects of Chern-Simons theory on L(p,q) lens spaces and its
relation with matrix models and topological string theory on Calabi-Yau
threefolds, searching for possible new large N dualities via geometric
transition for non-SU(2) cyclic quotients of the conifold. To this aim we find,
on one hand, some novel matrix integral representations of the SU(N) CS
partition function in a generic flat background for the whole L(p,q) family and
provide a solution for its large N dynamics; on the other, we perform in full
detail the construction of a family of would-be dual closed string backgrounds
via conifold geometric transition from T^*L(p,q). We can then explicitly prove
that Gopakumar-Vafa duality in a fixed vacuum fails in the case q>1, and
briefly discuss how it could be restored in a non-perturbative setting.Comment: 17 pages, 6 figures; references adde
Postprandial increases in nitrogenous excretion and urea synthesis in the Chinese soft-shelled turtle, Pelodiscus sinensis
10.1007/s00360-006-0105-8Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology177119-29JCPB