80,266 research outputs found
Tunnelling of topological line defects in strongly coupled superfluids
The geometric theory of vortex tunnelling in superfluid liquids is developed.
Geometry rules the tunnelling process in the approximation of an incompressible
superfluid, which yields the identity of phase and configuration space in the
vortex collective co-ordinate. To exemplify the implications of this approach
to tunnelling, we solve explicitly for the two-dimensional motion of a point
vortex in the presence of an ellipse, showing that the hydrodynamic collective
co-ordinate description limits the constant energy paths allowed for the vortex
in configuration space. We outline the experimental procedure used in helium II
to observe tunnelling events, and compare the conclusions we draw to the
experimental results obtained so far. Tunnelling in Fermi superfluids is
discussed, where it is assumed that the low energy quasiparticle excitations
localised in the vortex core govern the vortex dynamical equations. The
tunnelling process can be dominated by Hall or dissipative terms, respectively
be under the influence of both, with a possible realization of this last
intermediate case in unconventional, high-temperature superconductors.Comment: 51 pages, 15 figures, uses Ann. Phys. (Leipzig) style file; forms
part of author's dissertation, available at
http://xxx.lanl.gov/abs/cond-mat/9909166v
The Business of Human Resources
[Excerpt] The result of this missing ingredient is the basic reason for the variability that exists within the profession. In fact, a lot of business leaders do not clearly understand what HR is responsible or accountable for. Many are quick to relegate HR to social initiatives planning (e.g., United Way drives, company picnics), missing the value the function can provide to the business. In this paper I seek to address these issues by suggesting a four-factor framework for running the HR function like a business: (1) understanding the business HR is supporting, (2) developing a basic operating philosophy, (3) determining which HR products and services should be linked directly to business success, and (4) operating HR as a business
Interleaving device
An interleaving device for processing energy signals between various logic devices has a first number of spaced energy carrying layer mateials. Each of the first layer materials has a number of juxtaposed conduits passing energy signals through which are passed. Each of the conduits has a longitudinal axis substantially parallel to a diagonal of each of the first layers. A second group of energy carrying materials is arranged between adjacent ones of the spaced first layer materials. Each of the second layer materials has a number of juxtaposed conduits through which the energy signals are also passed. Each of the conduits in the second layer has a longitudinal axis substantially parallel to a diagonal of each of the second layer materials and substantially perpendicular to the axes of the conduits of the first layer materials
Aspects of quark mass generation on a torus
In this talk we report on recent results for the quark propagator on a
compact manifold. The corresponding Dyson-Schwinger equations on a torus are
solved on volumes similar to the ones used in lattice calculations. The
quark-gluon interaction is fixed such that the lattice results are reproduced.
We discuss both the effects in the infinite volume/continuum limit as well as
effects when the volume is small.Comment: 3 pages, 3 figures; talk given by CF at QNP06, Madrid, June 200
Transfer and storage of qubits in the presence of decoherence
The effects of decoherence on the transfer and storage of coherent quantum
states in hybrid systems are studied within the Caldeira-Leggett approach. In
general, we find that a high transfer fidelity can be achieved even if the
decoherence time is less than an order of magnitude larger than the transfer
time, which is approximately half a Rabi period and determined by the
qubit-qubit coupling strength. Finally, we apply our results to assess the
feasibility of a hybrid quantum memory system, comprised of the hyperfine qubit
states of an ultracold atomic Bose-Einstein condensate and the flux qubit of a
SQUID.Comment: 6 pages of EPL2, 3 figure
Dissociating effect of chromophore modifications on C-phycocyanin heterohexamers
The bilin chromophores of the α or β subunit of C-phycocyanin (PC) from Mastigocladus laminosus were modified, and subsequently recombined with the respective complementary unmodified chromophores. The modifications consisted of photobleaching (350 nm) or reversible reduction of the verdin- to rubin-type chromophore(s). Recombination led to heterodimers (αβ)1, but the heterohexameric aggregation state (αβ)3 could not be obtained with the modified chromophores. Autoxidation of the reduced α-84 chromophore in such a hybrid, which occurred on standing under aerobic conditions, induced reaggregation to heterohexamers. Chemical re-oxidation of the reduced chromophores did not produce reaggregation, and it was not promoted by a 22 kDa linker peptide fragment (Gottschalk et al., Photochem. Photobiol., 54 (1991) 283), which in unmodified samples stabilized heterohexameric aggregates. Binding of the mercurial p-chloromercury-benzenesulphonate to the single free cysteine of PC near (approximately 0.4 nm) the β-84 chromophore had only a moderately destabilizing effect on the heterohexamer (αβ)3. It was concluded that the intact chromophore structure is an important factor determining the quaternary structure of biliproteins. The tendency of heterohexamer destabilization is related to the situation in phycoerythrocyanin, where photoisomerization of the violobilin chromophore of the α subunit near the heterodimer—heterodimer contact region is also responsible for aggregate destabilization (Siebzehnrübl et al., Photochem. Photobiol., 46 (1989) 753)
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