10,413 research outputs found

    A monopole solution in a Lorentz-violating field theory

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    I present a topological defect solution that arises in a theory where Lorentz symmetry is spontaneously broken by a rank-two antisymmetric tensor field, and I discuss its observational signatures.Comment: 4 pages, 1 figur

    Lorentz violation and topological defects

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    If Lorentz symmetry is broken, it must have occurred dynamically, via a vector or tensor field whose potential energy forces it to take on a non-zero background expectation value "in vacuum". If the set of minima of this potential (the vacuum manifold) has a non-trivial topology, then there can arise topological defects: stable solutions in which the field approaches different potential minima as we go to infinity in different directions. I discuss the current status of research into these topological defects in the context of Lorentz symmetry breaking, including recent results concerning the birefringent light-bending of monopole solutions, and the search for models supporting cosmic-string and domain-wall defects.Comment: 4 pages. Presented at the Sixth Meeting on CPT and Lorentz Symmetry, Bloomington, Indiana, June 17-21, 201

    Thermodynamics of genuine non-equilibrium states under feedback control

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    For genuine non-equilibrium states that even at fixed external control parameter exhibit dissipation, we extend the Hatano-Sasa equality to processes with feedback control. The resulting bound on the maximal extractable work is substantially sharper than what would follow from applying the Sagawa-Ueda equality to transitions involving such states. For repeated measurements at short enough intervals, the power thus extracted can even exceed the average cost of driving as demonstrated explicitly with a simple, analytically solvable example.Comment: 5 pages, 3 figure

    A Builder's Guide to Water and Energy

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    The work on which this report is based was supported in part by funds provided by the Office of Water Research and Technology (Project A-Q65-ALAS), US. Department of the interior, Washington, D.C., as authorized by the Water Research and Development Act of 1978

    Solar Energy Resource Potential in Alaska

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    Solar energy applications are receiving attention in Alaska as in much of the rest of the country. Solar energy possibilities for Alaska include domestic water heating, hot-water or hot-air collection for space heating, and the use of passive solar heating in residential or commercial buildings. As a first analysis, this study concentrated on applying solar energy to domestic hot-water heating needs (not space heating) in Alaska, and an analysis of solar hot-water heating economics was performed using the F-CHART solar energy simulation computer program. Results indicate that solar energy cannot compete economically with oil-heated domestic hot water at any of the five study locations in Alaska, but that it may be economical in comparison with electrically heated hot water if solar collector systems can be purchased and installed for 20to20 to 25 per square foot.This work was made possible by a grant from the Solar Planning Office, West, 3333 Quebec, Denver, Colorado. It was performed as the Alaskan response to a western regional solar energy planning grant from the U. S. Department of Energy. The authors wish to acknowledge the support and cooperation of the Alaska State Department of Commerce, Division of Energy and Power Development, through whose efforts the grant was made available, especially Clarissa Quinlan, Grant Peterson, and Don Markle

    Extracting work from a single heat bath through feedback

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    Work can be extracted from a single heat bath if additional information is available. For the paradigmatic case of a Brownian particle in a harmonic potential, whose position has been measured with finite precision, we determine the optimal protocol for manipulating the center and stiffness of the potential in order to maximize this work in a finite-time process. The bound on this work imposed by a generalized second law inequality involving information can be reached only if both position and stiffness of the potential are controlled and the process is quasistatic. Estimates on the power delivered by such an "information machine" operating cyclically follow from our analytical results.Comment: 6 pages, 3 figure

    Hydrologic Properties of Subarctic Organic Soils

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    Completion Report for U. S. Forest Service Institute of Northern Forestry Cooperative Agreement No. 16 USC 581; 581a-581iThe need for understanding the natural system and how it responds to various stresses is important; this is especially so in an environment where the climate not only sustains permafrost, but develops massive seasonal frost as well. Consequently, the role of the shallow surface organic layer is also quite important. Since a slight change in the soil thermal regime may bring about a phase change in the water or ice, therefore, the system response to surface alterations such as burning can be quite severe. The need for a better understanding of the behavior and properties of the organic layer is, therefore, accentuated. The central theme of this study was the examination of the hydrologic and hydraulic properties of subarctic organic soils. Summarized in this paper are the results of three aspects of subarctic organic soil examinations conducted during the duration of the project. First, a field site was set up in Washington Creek with the major emphasis on measuring numerous variables of that soil system during the summer. The greatest variations in moisture content occur in the thick organic soils that exist at this site. Our major emphasis was to study the soil moisture levels in these soils. This topic is covered in the first major section, including associated laboratory studies. Those laboratory studies include investigations of several hydraulic and hydrologic properties of taiga organic and mineral soils. Second, some field data on organic moisture levels was collected at the site of prescribed burns in Washington Creek to ascertain the sustainability of fires as a function of moisture levels. This portion of the study is described under the second major heading. The last element of this study was a continued application of the two-dimensional flow model that was developed in an earlier study funded by the U. S. Forest Service, Institute of Northern Forestry, and reported by Kane, Luthin, and Taylor (1975a). Many of the results and concepts gathered in the field work were integrated into the modeling effort, which is aimed at producing better estimates of the hydrologic effects of surface disturbances in the black spruce taiga subarctic ecosystem. This knowledge should also contribute to better fire management decisions of the same system.The work upon which this report is based was made possible by a cooperative aid agreement funded by the U. S. Forest Service, Institute of Northern Forestry, Fairbanks, Alaska. Contribution to this study was also made by Ohio State University
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