23,723 research outputs found
Flexible thermal device
Fabrication of expansion joint, vibration isolator device with sufficient cross sectional area for high thermal conductivity is discussed. Device consists of multiple layers of metal foil which may be designed to meet specific applications. Thermodynamic properties of the device and illustration of construction are provided
Low-energy interaction of composite spin-half systems with scalar and vector fields
We consider a composite spin-half particle moving in spatially-varying scalar
and vector fields. The vector field is assumed to couple to a conserved charge,
but no assumption is made about either the structure of the composite or its
coupling to the scalar field. A general form for the piece of the spin-orbit
interaction of the composite with the scalar and vector fields which is
first-order in momentum transfer and second-order in the fields is
derived.Comment: 10 pages, RevTe
and Perelomov number coherent states: algebraic approach for general systems
We study some properties of the Perelomov number coherent states.
The Schr\"odinger's uncertainty relationship is evaluated for a position and
momentum-like operators (constructed from the Lie algebra generators) in these
number coherent states. It is shown that this relationship is minimized for the
standard coherent states. We obtain the time evolution of the number coherent
states by supposing that the Hamiltonian is proportional to the third generator
of the Lie algebra. Analogous results for the Perelomov
number coherent states are found. As examples, we compute the Perelomov
coherent states for the pseudoharmonic oscillator and the two-dimensional
isotropic harmonic oscillator
On the accuracy of the melting curves drawn from modelling a solid as an elastic medium
An ongoing problem in the study of a classical many-body system is the
characterization of its equilibrium behaviour by theory or numerical
simulation. For purely repulsive particles, locating the melting line in the
pressure-temperature plane can be especially hard if the interparticle
potential has a softened core or contains some adjustable parameters. A method
is hereby presented that yields reliable melting-curve topologies with
negligible computational effort. It is obtained by combining the Lindemann
melting criterion with a description of the solid phase as an elastic
continuum. A number of examples are given in order to illustrate the scope of
the method and possible shortcomings. For a two-body repulsion of Gaussian
shape, the outcome of the present approach compares favourably with the more
accurate but also more computationally demanding self-consistent harmonic
approximation.Comment: 25 pages, 7 figure
The Results of Treatment with Streptomycin Plus Pyrazinamide in Patients with Active Pulmonary Tuberculosis Despite Prolonged Treatment with Isoniazid Plus PAS
This report presents the findings during a year or more of observation of
20 South Indian patients who, after an initial course of isoniazid plus PAS, were
treated with streptomycin plus pyrazinamide for active pulmonary tuberculosis. The
combination of streptomycin plus pyrazinamide was chosen, first, because of its
likely therapeutic effectiveness, since all the patients had streptomycin-sensitive
strains of bacilli, secondly, because it presented an opportunity to study supervised
drug administration in domiciliary patients in a community in which the selfadministration
of antituberculosis drugs could not be depended on (Fox, 1958 ;
Tuberculosis Chemotherapy Centre, 1959, 1960 ; Velu et al., 1960). The patients were
either unsuitable for or unwilling to undergo surgery
Can Everett be Interpreted Without Extravaganza?
Everett's relative states interpretation of quantum mechanics has met with
problems related to probability, the preferred basis, and multiplicity. The
third theme, I argue, is the most important one. It has led to developments of
the original approach into many-worlds, many-minds, and decoherence-based
approaches. The latter especially have been advocated in recent years, in an
effort to understand multiplicity without resorting to what is often perceived
as extravagant constructions. Drawing from and adding to arguments of others, I
show that proponents of decoherence-based approaches have not yet succeeded in
making their ontology clear.Comment: Succinct analysis forthcoming in Found. Phy
Comment on `Renormalization-Group Calculation of the Dependence on Gravity of the Surface Tension and Bending Rigidity of a Fluid Interface'
It is shown that the interface model introduced in Phys. Rev. Lett. 86, 2369
(2001) violates fundamental symmetry requirements for vanishing gravitational
acceleration , so that its results cannot be applied to critical properties
of interfaces for .Comment: A Comment on a recent Letter by J.G. Segovia-L\'opez and V.
Romero-Roch\'{\i}n, Phys. Rev. Lett.86, 2369 (2001). Latex file, 1 page
(revtex
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