6,188 research outputs found
Remote sensing utility in a disaster struck urban environment
Six major public health areas which might be affected by a natural disaster were identified. The functions and tasks associated with each area following a disaster, potential ways remote sensing could aid these functions, and the baseline data which would expedite problem solving associated with these functions are discussed
Classical-quantum correspondence in bosonic two-mode conversion systems: polynomial algebras and Kummer shapes
Bosonic quantum conversion systems can be modeled by many-particle
single-mode Hamiltonians describing a conversion of molecules of type A
into molecules of type B and vice versa. These Hamiltonians are analyzed in
terms of generators of a polynomially deformed algebra. In the
mean-field limit of large particle numbers, these systems become classical and
their Hamiltonian dynamics can again be described by polynomial deformations of
a Lie algebra, where quantum commutators are replaced by Poisson brackets. The
Casimir operator restricts the motion to Kummer shapes, deformed Bloch spheres
with cusp singularities depending on and . It is demonstrated that the
many-particle eigenvalues can be recovered from the mean-field dynamics using a
WKB type quantization condition. The many-particle state densities can be
semiclassically approximated by the time-periods of periodic orbits, which show
characteristic steps and singularities related to the fixed points, whose
bifurcation properties are analyzed.Comment: 13 pages, 13 figure
Potential role of remote sensing in disaster relief management
Baseline or predisaster data which would be useful to decision making in the immediate postdisaster period were suggested for the six areas of public health concern along with guidelines for organizing these data. Potential sources of these data are identified. In order to fully assess the impact of a disaster on an area, information about its predisaster status must be known. Aerial photography is one way of acquiring and recording such data
Quasiclassical analysis of Bloch oscillations in non-Hermitian tight-binding lattices
Many features of Bloch oscillations in one-dimensional quantum lattices with
a static force can be described by quasiclassical considerations for example by
means of the acceleration theorem, at least for Hermitian systems. Here the
quasiclassical approach is extended to non-Hermitian lattices, which are of
increasing interest. The analysis is based on a generalised non-Hermitian phase
space dynamics developed recently. Applications to a single-band tight-binding
system demonstrate that many features of the quantum dynamics can be understood
from this classical description qualitatively and even quantitatively. Two
non-Hermitian and -symmetric examples are studied, a Hatano-Nelson lattice
with real coupling constants and a system with purely imaginary couplings, both
for initially localised states in space or in momentum. It is shown that the
time-evolution of the norm of the wave packet and the expectation values of
position and momentum can be described in a classical picture.Comment: 20 pages, 8 figures, typos corrected, slightly extended, accepted for
publication in New Journal of Physics in Focus Issue on Parity-Time Symmetry
in Optics and Photonic
A Global Hypothesis for Women in Journalism and Mass Communications: The Ratio of Recurrent and Reinforced Residuum
This paper examines the status of women in communications industries and on university faculties. It specifically tests the Ratio of Recurrent and Reinforced Residuum or R3 hypothesis, as developed by Rush in the early 1980s [Rush, Buck & Ogan,1982]. The R3 hypothesis predicts that the percentage of women in the communications industries and on university faculties will follow the ratio residing around 1/4:3/4 or 1/3:2/3 proportion females to males. This paper presents data from a nationwide U.S. survey and compares them to data from global surveys and United Nations reports. The evidence is overwhelming and shows the relevance and validity of the R3 hypothesis across different socio-economic and cultural contexts. The paper argues that the ratio is the outcome of systemic discrimination that operates at multiple levels. The obstacles to achieving equality in the academy as well as media industries are discussed and suggestions for breaking out of the R3 ratio are included.
A Global Hypothesis for Women in Journalism and Mass Communications: The Ratio of Recurrent and Reinforced Residuum
This paper examines the status of women in communications industries and on university faculties. It specifically tests the Ratio of Recurrent and Reinforced Residuum or R3 hypothesis, as developed by Rush in the early 1980s [Rush, Buck & Ogan,1982]. The R3 hypothesis predicts that the percentage of women in the communications industries and on university faculties will follow the ratio residing around 1/4:3/4 or 1/3:2/3 proportion females to males. This paper presents data from a nationwide U.S. survey and compares them to data from global surveys and United Nations reports. The evidence is overwhelming and shows the relevance and validity of the R3 hypothesis across different socio-economic and cultural contexts. The paper argues that the ratio is the outcome of systemic discrimination that operates at multiple levels. The obstacles to achieving equality in the academy as well as media industries are discussed and suggestions for breaking out of the R3 ratio are included.
Soft X--Ray Properties of Seyfert Galaxies in the Rosat All--Sky Survey
We present the results of ROSAT All-Sky Survey observations of Seyfert and
IR-luminous galaxies from the Extended 12 Micron Galaxy Sample and the
optically-selected CfA Sample. Roughly half of the Seyferts (mostly Seyfert 1s)
have been fitted to an absorbed power-law model, yielding an average gamma of
2.26+-0.11 for 43 Seyfert 1s and 2.45+-0.18 for 10 Seyfert 2s, with both types
having a median value of 2.3.
The soft X-ray (SXR) luminosity correlates with the 12um luminosity, with
Seyfert 1s having relatively more SXR emission than Seyfert 2s of similar
mid-infrared luminosities, by a factor of 1.6+-0.3. Several physical
interpretations of these results are discussed, including the standard unified
model for Seyfert galaxies. Infrared-luminous non-Seyferts are shown to have
similar distributions of SXR luminosity and X-ray-to-IR slope as Seyfert 2s,
suggesting that some of them may harbor obscured active nuclei (as has already
been shown to be true for several objects) and/or that the soft X-rays from
some Seyferts 2s may be non-nuclear.
A SXR luminosity function (XLF) is calculated for the 12um sample, which is
well described by a single power-law with a slope of -1.75. The normalization
of this XLF agrees well with that of a HXR selected sample. Several of our
results, related to the XLF and the X-ray-to-IR relation are shown to be
consistent with the HXR observations of the 12um sample by Barcons et al.Comment: AASTeX, 40 pages. Text and Table 2 only. PostScript versions of this
file, figures, and Table 1, and a latex version of Table 1 are available by
ftp://ftp.astro.ucla.edu/pub/rush/papers, get rmfv*. Accepted by ApJ ~1996
May 10. Should be published in late 199
An Application of the Unscented Kalman Filter for Spacecraft Attitude Estimation on Real and Simulated Light Curve Data
In the past, analyses of lightcurve data have been applied to asteroids in order to determine their axis of rotation, rotation rate and other parameters. In recent decades, these analyses have begun to be applied in the domain of Earth orbiting spacecraft. Due to the complex geometry of spacecraft and the wide variety of parameters that can influence the way in which they reflect light, these analyses require more complex assumptions and a greater knowledge about the object being studied. Previous investigations have shown success in extracting attitude parameters from unresolved spacecraft using simulated data. This paper presents a focused attempt to derive attitude parameters using an Unscented Kalman Filter from both simulated and real data provided by Lockheed Martin Space.
This thesis characterizes and presents the differences in performance between three simulated geometries in low, medium, and geostationary orbit in both cases where they are spinning about a constant axis and in cases in which they are tumbling.
Additionally, this thesis hypothesizes and tests the idea that a predictable and extraneous angular velocity solution exists which is the reflection of the true solution about the plane defined by the sun and observation vectors. This thesis encountered multiple instances of this type solution appearing in simulation and provides an example as well as a visualization.
Finally, this thesis demonstrates the ability to converge to a solution from real data although there were large discrepancies between the measurement model and the data. This thesis discusses the validity of these solutions and sources of error
Richard L. Epstein, “Reasoning in Science and Mathematics: Essays on Logic as The Art of Reasoning Well”
Book Reviews: Richard L. Epstein, Reasoning in Science and Mathematics: Essayson Logic as The Art of Reasoning Well, Advanced Reasoning Forum,2011, 134 pp., ISBN-13: 978-0983452126, ISBN-10: 0983452121
Emission Line Properties of Seyfert Galaxies in the 12 Micron Sample
We present spectroscopy of emission lines for 81 Seyfert 1 and 104 Seyfert 2
galaxies in the IRAS 12m galaxy sample. We analyzed the emission-line
luminosity functions, reddening, and other gas diagnostics. The narrow-line
regions (NLR) of Sy1 and 2 galaxies do not significantly differ from each other
in most of these diagnostics. Combining the H/H ratio with a new
reddening indicator-the [SII]6720/[OII]3727 ratio, we find the average
for Sy1s and for Sy2s. The NLR of Sy1
galaxies has only marginally higher ionization than the Sy2s. Our sample
includes 22 Sy1.9s and 1.8s. In their narrow lines, these low-luminosity
Seyferts are more similar to the Sy2s than the Sy1s. We construct a BPT
diagram, and include the Sy1.8s and 1.9s. They overlap the region occupied by
the Sy2s. The C IV equivalent width correlates more strongly with [O
III]/H than with UV luminosity. The Sy1 and Sy2 luminosity functions of
[OII]3727 and [OIII]5007 are indistinguishable. Unlike the LF's of Seyfert
galaxies measured by SDSS, ours are nearly flat at low L. The larger number of
faint Sloan "AGN" is attributable to their inclusion of weakly emitting LINERs
and H II+AGN "composite" nuclei, which do not meet our classification criteria
for Seyferts. An Appendix investigates which emission line luminosities provide
the most reliable measures of the total non-stellar luminosity. The hard X-ray
or near-ultraviolet continuum luminosity can be crudely predicted from either
the [O III]5007 luminosity, or the combination of [O III]+H, or [N
II]+H lines, with a scatter of times for the Sy1s and
times for the Sy2s. The latter two hybrid (NLR+BLR) indicators have
the advantage of predicting the same HX luminosity independent of Seyfert type.Comment: 70 pages, including 15 Figures and 10 Tables. Accepted for
publication in The Astrophysical Journa
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