12,619 research outputs found
Chern-Simons terms from thermal circles and anomalies
We compute the full contribution of flavor and (or) Lorentz anomalies to the
thermodynamic partition function. Apart from the Wess-Zumino consistency
condition the Euclidean generating function must satisfy an extra requirement
which we refer to as `consistency with the Euclidean vacuum.' The latter
requirement fixes all Chern-Simons terms that arise in a particular
Kaluza-Klein reduction of the theory. The solution to both conditions may be
encoded in a `thermal anomaly polynomial' which we compute. Our construction
fixes all the thermodynamic response parameters of a hydrodynamic theory
associated with anomalies.Comment: 30 page
Probing Noise in Gene Expression and Protein Production
We derive exact solutions of simplified models for the temporal evolution of
the protein concentration within a cell population arbitrarily far from the
stationary state. We show that monitoring the dynamics can assist in modeling
and understanding the nature of the noise and its role in gene expression and
protein production. We introduce a new measure, the cell turnover distribution,
which can be used to probe the phase of transcription of DNA into messenger
RNA.Comment: 10 pages, 3 figures, supplementary information on reques
Proton scattering observables from Skyrme-Hatree-Fock densities
Proton and neutron densities from Skyrme-Hartree-Fock (SHF) calculations are
used to generate non-local (g-folding) proton-nucleus optical potentials. They
are formed by folding the densities with realistic nucleon-nucleon
interactions. The potentials are then used to calculate differential cross
sections and spin observables for proton scattering. Good agreement with data
has been found, supporting those found previously when using SHF charge
densities in analyses of electron scattering data. That agreement was improved
by use of (shell model) occupation numbers to constrain the HF iterations.
That, in part, is also the case with analyses of proton scattering data. The
g-folding method is extended to exotic nuclei by including data for
neutron-rich sd-shell nuclei from the inverse kinematics of scattering from
hydrogen.Comment: 18 pages, 16 figures, submitted to Nuclear Physics
Outgoing gravitational shock-wave at the inner horizon: The late-time limit of black hole interiors
We investigate the interiors of 3+1 dimensional asymptotically flat charged
and rotating black holes as described by observers who fall into the black
holes at late times, long after any perturbations of the exterior region have
decayed. In the strict limit of late infall times, the initial experiences of
such observers are precisely described by the region of the limiting stationary
geometry to the past of its inner horizon. However, we argue that late
infall-time observers encounter a null shockwave at the location of the
would-be outgoing inner horizon. In particular, for spherically symmetric black
hole spacetimes we demonstrate that freely-falling observers experience a
metric discontinuity across this shock, that is, a gravitational shock-wave.
Furthermore, the magnitude of this shock is at least of order unity. A similar
phenomenon of metric discontinuity appears to take place at the inner horizon
of a generically-perturbed spinning black hole. We compare the properties of
this null shockwave singularity with those of the null weak singularity that
forms at the Cauchy horizon.Comment: 23 pages, 4 figures, minor change
Study of an attitude reference system utilizing an electrically suspended gyro final report, 1 aug. 1964 - 31 mar. 1965
Miniature electrically suspended gyroscope for spacecraft attitude reference syste
Neutral Theory and Relative Species Abundance in Ecology
The theory of island biogeography[1] asserts that an island or a local
community approaches an equilibrium species richness as a result of the
interplay between the immigration of species from the much larger metacommunity
source area and local extinction of species on the island (local community).
Hubbell[2] generalized this neutral theory to explore the expected steady-state
distribution of relative species abundance (RSA) in the local community under
restricted immigration. Here we present a theoretical framework for the unified
neutral theory of biodiversity[2] and an analytical solution for the
distribution of the RSA both in the metacommunity (Fisher's logseries) and in
the local community, where there are fewer rare species. Rare species are more
extinction-prone, and once they go locally extinct, they take longer to
re-immigrate than do common species. Contrary to recent assertions[3], we show
that the analytical solution provides a better fit, with fewer free parameters,
to the RSA distribution of tree species on Barro Colorado Island (BCI)[4] than
the lognormal distribution[5,6].Comment: 19 pages, 1 figur
Energy Conversion Alternatives Study (ECAS), Westinghouse phase 1. Volume 5: Combined gas-steam turbine cycles
The energy conversion efficiency of gas-steam turbine cycles was investigated for selected combined cycle power plants. Results indicate that it is possible for combined cycle gas-steam turbine power plants to have efficiencies several point higher than conventional steam plants. Induction of low pressure steam into the steam turbine is shown to improve the plant efficiency. Post firing of the boiler of a high temperature combined cycle plant is found to increase net power but to worsen efficiency. A gas turbine pressure ratio of 12 to 1 was found to be close to optimum at all gas turbine inlet temperatures that were studied. The coal using combined cycle plant with an integrated low-Btu gasifier was calculated to have a plant efficiency of 43.6%, a capitalization of $497/kW, and a cost of electricity of 6.75 mills/MJ (24.3 mills/kwh). This combined cycle plant should be considered for base load power generation
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