10,413 research outputs found
A monopole solution in a Lorentz-violating field theory
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
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
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
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
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 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
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
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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