11,586 research outputs found
Faddeev treatment of long-range correlations and the one-hole spectral function of O16
The Faddeev technique is employed to study the influence of both
particle-particle and particle-hole phonons on the one-hole spectral function
of O16.
Collective excitations are accounted for at a random phase approximation
level and subsequently summed to all orders by the Faddeev equations to obtain
the nucleon self-energy. An iterative procedure is applied to investigate the
effects of the self-consistent inclusion of the fragmentation in the
determination of the phonons and the corresponding self-energy. The present
results indicate that the characteristics of hole fragmentation are related to
the low-lying states of O16.Comment: 10 pages, 6 figures, 3 tables. Submitted to Phys.Rev.
Improved Method of Determining Metabolic Function
The present invention provides a novel lactate difference imaging (LDI) technique, allowing assessment of the metabolic response to tissue over a period of time. This approach utiliizes lactate change over a time period as an indiactor of viable tissue, and offers benefits in the management and treatment of the effects of many common diseases, in particular stroke
The Effect of Dissolved Water on the Tribological Properties of Polyalkylene Glycol and Polyolester Oils
The effect of water dissolved in polyalkylene glycol and polyolester oils on the
tribological behavior of two material contact pairs in three test environments is evaluated. The
material contact pairs are M2 tool steel against 390 aluminum and M2 tool steel against gray
cast iron. The three oils are a polyalkylene glycol (PAG) and two polyolester (PEl and PE2)
oils. The test environments are R134a, air and argon. The tests are conducted in a specially
designed high pressure tribometer which provides an accurate control of the test variables.
The results indicate that the P AG oil performed better than the esters for both material
contact pairs. The wear on the aluminum plates for the tests conducted with the P AG oil in all
three environments is greatest at the lowest moisture content levels. From the stand point of
friction and wear, it is beneficial to have a water content level of 5000 ppm or greater in the
PAG oil when the plate material is 390 aluminum. The wear on the cast iron plates, when using
a PAG oil as the lubricant showed a slight increase with water content in a R134a environment.
This trend is opposite when air is the test environment.
Both ester oils lubricated aluminum much better than the cast iron . The difference in
the amount of wear can be as high as two orders of magnitude. This is probably due to the
ability of the esters to form bidentate bonds with aluminum. Esters do not form such bonds
with iron. The plate wear is greater for the PEl tests than for the PE2 tests for both material
contact pairs. This is most likely due to the difference in the viscosity of the oils. In PE2 oil,
water does not seem to affect the friction and wear of both aluminum/steel and cast iron/steel
contacts when R134a is the test environment. On the contrary, for the aluminum/steel contacts,
the water content significantly influences wear when argon or air is the test environment. For
the cast iron/steel contacts, the wear is strongly influenced by the water content when the test is
conducted in argon, but it is not influenced by the water content when the test is conducted in
air.Air Conditioning and Refrigeration Center Project 0
Decoherence, Re-coherence, and the Black Hole Information Paradox
We analyze a system consisting of an oscillator coupled to a field. With the
field traced out as an environment, the oscillator loses coherence on a very
short {\it decoherence timescale}; but, on a much longer {\it relaxation
timescale}, predictably evolves into a unique, pure (ground) state. This
example of {\it re-coherence} has interesting implications both for the
interpretation of quantum theory and for the loss of information during black
hole evaporation. We examine these implications by investigating the
intermediate and final states of the quantum field, treated as an open system
coupled to an unobserved oscillator.Comment: 23 pages, 2 figures included, figures 3.1 - 3.3 available at
http://qso.lanl.gov/papers/Papers.htm
Numerical computation of real or complex elliptic integrals
Algorithms for numerical computation of symmetric elliptic integrals of all
three kinds are improved in several ways and extended to complex values of the
variables (with some restrictions in the case of the integral of the third
kind). Numerical check values, consistency checks, and relations to Legendre's
integrals and Bulirsch's integrals are included
Entropy and Wigner Functions
The properties of an alternative definition of quantum entropy, based on
Wigner functions, are discussed. Such definition emerges naturally from the
Wigner representation of quantum mechanics, and can easily quantify the amount
of entanglement of a quantum state. It is shown that smoothing of the Wigner
function induces an increase in entropy. This fact is used to derive some
simple rules to construct positive definite probability distributions which are
also admissible Wigner functionsComment: 18 page
What is "system": the information-theoretic arguments
The problem of "what is 'system'?" is in the very foundations of modern
quantum mechanics. Here, we point out the interest in this topic in the
information-theoretic context. E.g., we point out the possibility to manipulate
a pair of mutually non-interacting, non-entangled systems to employ
entanglement of the newly defined '(sub)systems' consisting the one and the
same composite system. Given the different divisions of a composite system into
"subsystems", the Hamiltonian of the system may perform in general
non-equivalent quantum computations. Redefinition of "subsystems" of a
composite system may be regarded as a method for avoiding decoherence in the
quantum hardware. In principle, all the notions refer to a composite system as
simple as the hydrogen atom.Comment: 13 pages, no figure
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