Minimal coupling in oscillator models of quantum dissipation

The dissipative harmonic oscillator has two representations. In the first representation the central oscillator couples with its position to an oscillator bath. In the second one it couples with its momentum to the bath. Both representations are related by a unitary transformation. If the central oscillator couples with its position and momentum to two independent baths, no such unitary transformation exists. We discuss two possible models of this type and their physical relevance

Studies on the Life Cycle and Transmission of \u3ci\u3eCougourdella\u3c/i\u3e Sp., A Microsporidian Parasite of \u3ci\u3eGlossosoma Nigrior\u3c/i\u3e (Trichoptera: Glossosomatidae)

The trichopteran Glossosoma nigrior, the dominant benthic invertebrate grazer in Michigan trout streams, hosts a microsporidian (Protozoa) pathogen, Cougourdella sp., which strongly regulates the population density of larvae in the stream. In order to better understand the interactions between these two species, two possible modes of pathogen transmission, oral and transovum, were investigated. While both sexes of adult G. nigrior were found to be infected with mature environmental spores, spores were not found associated with reproductive tissue. This suggests that transovum transmission does not occur in this system. Glossosoma nigrior, when ex- posed to viable spores taken from infected larvae, did not produce Cougourdella sp. infections, which suggests that oral transmission also does not occur. It is possible that an intermediate host is required

Geology, Characteristics, and Resource Potential of the Low-Temperature Geothermal System Near Midway, Wasatch County, Utah

Recent awareness of the finite nature of fossil-fuel resources has resulted in an increased interest in alternate sources of energy such as geothermal. To evaluate the geothermal energy potential of the hot springs system near Midway, Wasatch Co., Utah, consideration was given to heat flow, water chemistry, and structural controls. Abnormal heat flow was indicated qualitatively by snow-melt patterns and quantitatively by heat-flow measurements that were obtained from two of four temperature-gradient wells drilled in the area. These measurements indicated that the area north of the town of Midway is characterized by heat flow equal to 321.75 mW/m2, which is over four times the value generally considered as normal heat flow. Chemical analyses of water from six selected thermal springs and wells were used in conjunction with the silica and Na-K-Ca geothermometers to estimate the reservoir temperature of the thermal system. Because the calculated temperature was more than 25 degrees C above the maximum observed temperature, a mixing model calculation was used to project an upper limit for the reservoir temperature. Based on these calculations, the system has a reservoir temperature ranging from 46 to 125 degrees C. Structural information obtained from published from published geologic maps of the area and from an unpublished gravity survey, enabled two models to be developed for the system. The first model, based geologic relationships in the mountains to the north and west of Midway, assumes that the heat for the thermal system comes from a relatively young intrusive or related hydrothermal convection system in the vicinity of the Mayflower mine. Meteoric waters would be heated as they approach the heat source and then move laterally to the south through faults and fractures in the rocks. These thermal waters then rise to the surface through fractures in the crest of an anticline underneath the Midway area. The second model, based on the gravity survey, assumes an igneous intrusion directly beneath Midway as the heat source. The first model is considered more likely. The Midway geothermal system is a low temperature resource, suitable for space-heating and other direct-use applications

Of Flags And Menorahs: The Power Of Individual And Governmental Symbolic Speech

The aim of this article will be to explore the nature of symbolic speech, both individual and governmental. Using Johnson and Allegheny County as a backdrop, four themes will emerge from the article. First, both individuals and government speak and speak powerfully through symbols and symbolic conduct. Second, medium-based regulation of individual speech should receive careful judicial scrutiny. Third, unlike individual symbolic expression, governmental symbolic speech is subject to substantial content-based restrictions. Finally, careful distinctions must be drawn between government-initiated symbolic speech and governmental endorsement of individual symbolic speech

Coulomb blockade effects in driven electron transport

We study numerically the influence of strong Coulomb repulsion on the current through molecular wires that are driven by external electromagnetic fields. The molecule is described by a tight-binding model whose first and last site is coupled to a respective lead. The leads are eliminated within a perturbation theory yielding a master equation for the wire. The decomposition into a Floquet basis enables an efficient treatment of the driving field. For the electronic excitations in bridged molecular wires, we find that strong Coulomb repulsion significantly sharpens resonance peaks which broaden again with increasing temperature. By contrast, Coulomb blockade has only a small influence on effects like non-adiabatic electron pumping and coherent current suppression.Comment: 9 pages, 7 figures. Added a plot for temperature dependence of resonance peaks. Published versio

Surprising relations between parametric level correlations and fidelity decay

Unexpected relations between fidelity decay and cross form--factor, i.e., parametric level correlations in the time domain are found both by a heuristic argument and by comparing exact results, using supersymmetry techniques, in the framework of random matrix theory. A power law decay near Heisenberg time, as a function of the relevant parameter, is shown to be at the root of revivals recently discovered for fidelity decay. For cross form--factors the revivals are illustrated by a numerical study of a multiply kicked Ising spin chain.Comment: 4 pages 3 figure