Population inversion of driven two-level systems in a structureless bath

We derive a master equation for a driven double-dot damped by an unstructured phonon bath, and calculate the spectral density. We find that bath mediated photon absorption is important at relatively strong driving, and may even dominate the dynamics, inducing population inversion of the double dot system. This phenomenon is consistent with recent experimental observations.Comment: 4 Pages, Added Reference [30] to Dykman, 1979, available at http://www.pa.msu.edu/people/dykman/pub/Sov.J.LowTemp.Phys_5.pd

Personal propulsion unit Patent

Lightweight propulsion unit for movement of personnel and equipment across lunar surfac

Diets of shags Phalacrocorax aristotelis and cormorants P. carbo in Norway and possible implications for gadoid stock recruitment

The diets of shags and cormorants were studied in Norway through analyses of regurgitated pellets. Although this method has many limitations, indications were that both species rely heavily on small gadoids (Gadidae) and sand eels (Ammodytidae) for food throughout their range, but also eat other fish species when available. There was considerable dietary overlap between species, despite a tendency for cormorants to eat larger fish and more benthic items than shags. Predation by shags and cormorants could be a factor limiting the recruitment of cod and saithe into what are now severely reduced, but commercially important stocks in the Norwegian and Barents Seas

Manifestation of three-body forces in f7/2-shell nuclei

The traditional nuclear shell model approach is extended to include many-body forces. The empirical Hamiltonian with a three-body force is constructed for the identical nucleons on the 0f7/2 shell. Manifestations of the three-body force in spectra, binding energies, seniority mixing, particle-hole symmetry, electromagnetic and particle transition rates are investigated. It is shown that in addition to the usual expansion of the valence space within the tranditional two-body shell model, the three-body component in the Hamiltonian can be an important part improving the quality of the theoretical approach.Comment: 5 pages, 1 figur

AS-204/LM-1 launch vehicle operational flight trajectory

Apollo Saturn-204/LM-1 launch vehicle operational flight trajector

The Construction of Sorkin Triangulations

Some time ago, Sorkin (1975) reported investigations of the time evolution and initial value problems in Regge calculus, for one triangulation each of the manifolds $R*S^3$ and $R^4$. Here we display the simple, local characteristic of those triangulations which underlies the structure found by Sorkin, and emphasise its general applicability, and therefore the general validity of Sorkin's conclusions. We also make some elementary observations on the resulting structure of the time evolution and initial value problems in Regge calculus, and add some comments and speculations.Comment: 5 pages (plus one figure not included, available from author on request), Plain Tex, no local preprint number (Only change: omitted "\magnification" command now replaced

Study of the ground-state energy of 40Ca with the CD-Bonn nucleon-nucleon potential

We have calculated the ground-state energy of the doubly-magic nucleus 40Ca within the framework of the Goldstone expansion using the CD-Bonn nucleon-nucleon potential. The short-range repulsion of this potential has been renormalized by integrating out its high-momentum components so as to derive a low-momentum potential V-low-k defined up to a cutoff momentum Lambda. A simple criterion has been employed to establish a connection between this cutoff momentum and the size of the two-nucleon model space in the harmonic oscillator basis. This model-space truncation approach provides a reliable way to renormalize the free nucleon-nucleon potential preserving its many-body physics. The role of the 3p-3h and 4p-4h excitations in the description of the ground state of 40Ca is discussed.Comment: 4 pages, 1 figure, 1 table, to be published in Physical Review

The complete LQG propagator: I. Difficulties with the Barrett-Crane vertex

Some components of the graviton two-point function have been recently computed in the context of loop quantum gravity, using the spinfoam Barrett-Crane vertex. We complete the calculation of the remaining components. We find that, under our assumptions, the Barrett-Crane vertex does not yield the correct long distance limit. We argue that the problem is general and can be traced to the intertwiner-independence of the Barrett-Crane vertex, and therefore to the well-known mismatch between the Barrett-Crane formalism and the standard canonical spin networks. In a companion paper we illustrate the asymptotic behavior of a vertex amplitude that can correct this difficulty.Comment: 31 page

An algebraic interpretation of the Wheeler-DeWitt equation

We make a direct connection between the construction of three dimensional topological state sums from tensor categories and three dimensional quantum gravity by noting that the discrete version of the Wheeler-DeWitt equation is exactly the pentagon for the associator of the tensor category, the Biedenharn-Elliott identity. A crucial role is played by an asymptotic formula relating 6j-symbols to rotation matrices given by Edmonds.Comment: 10 pages, amstex, uses epsf.tex. New version has improved presentatio