56,127 research outputs found
New vacuum solutions of conformal Weyl gravity
The Bach equation, i.e., the vacuum field equation following from the
Lagrangian L=C_{ijkl}C^{ijkl}, will be completely solved for the case that the
metric is conformally related to the cartesian product of two 2-spaces; this
covers the spherically and the plane symmetric space-times as special subcases.
Contrary to other approaches, we make a covariant 2+2-decomposition of the
field equation, and so we are able to apply results from 2-dimensional gravity.
Finally, some cosmological solutions will be presented and discussed.Comment: 15 pages, LaTeX, no figures, submitted to J. Math. Phy
On a Possibility to Measure Thermoelectric Power in SNS Structures
Two dissimilar Josephson junctions, which are connected to a heater can act
as precise batteries. Because of the difference in thermoelectric power of
these batteries, circuit with two dissimilar batteries, under heat flow would have a net EMF around the zero-resistance
loop leading to a loop's magnetic flux oscillating in time. It is shown its
theoretical value is proportional to both the temperature difference as well as
the disparity in the thermoelectric powers of the two junctions.Comment: 5 page
A two-dimensional representation of four-dimensional gravitational waves
The Einstein equation in D dimensions, if restricted to the class of
space-times possessing n = D - 2 commuting hypersurface-orthogonal Killing
vectors, can be equivalently written as metric-dilaton gravity in 2 dimensions
with n scalar fields. For n = 2, this results reduces to the known reduction of
certain 4-dimensional metrics which include gravitational waves. Here, we give
such a representation which leads to a new proof of the Birkhoff theorem for
plane-symmetric space--times, and which leads to an explanation, in which sense
two (spin zero-) scalar fields in 2 dimensions may incorporate the (spin two-)
gravitational waves in 4 dimensions. (This result should not be mixed up with
well--known analogous statements where, however, the 4-dimensional space-time
is supposed to be spherically symmetric, and then, of course, the equivalent
2-dimensional picture cannot mimic any gravitational waves.) Finally, remarks
on hidden symmetries in 2 dimensions are made.Comment: 12 pages, LaTeX, no figures, Int. J. Mod. Phys. D in prin
Reaction mechanisms involved in the production of neutron-rich isotopes
The reaction mechanisms best suited for the production of neutron-rich
nuclei, fragmentation and fission, are discussed. Measurements of the
production cross sections of reaction residues together with model calculations
allow to conclude about the expected production rates of neutron-rich isotopes
in future facilities.Comment: 9 pages, 8 figures Proceedings of the Third International Conference
on Fission and Properties of Neutron-Rich Nuclei November 3-9, 2002, Sanibel
Island, Florida, US
Fano interference effect on the transition spectrum of single electron transistors
We theoretically study the intraband transition spectrum of single electron
transistors (SETs) composed of individual self-assembled quantum dots. The
polarization of SETs is obtained by using the nonequilibrium Green's function
technique and the Anderson model with three energy levels. Owing to
nonradiative coupling between two excited states through the continuum of
electrodes, the Fano interference effect significantly influences the peak
position and intensity of infrared wavelength single-photon spectrum.Comment: 4 pages, 5 figure
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