1,403 research outputs found
Urgent Aeromedical Evacuation Network Capacity Planning
Aeromedical Evacuation (AE) has been steadily utilized during Operation Iraqi Freedom and Operation Enduring Freedom. AE is a global enterprise. The current structure of AE is facing changes as forces scale down from operations in Iraq and Afghanistan. AE will, however, continue to be important in its domestic use in the continental USA (CONUS). Current practice is to pull aircraft (e.g. C-17, C-130 or KC-135) from their normal operations to meet Urgent and Priority patient needs when local alternatives are infeasible. An alternative to the current system would be having a centralized bed-down location for AE operations that would house dedicated aircraft as well as AE personnel. In this thesis, a hybrid queuing and discrete-event simulation approach is used to determine how many aircraft are needed for a given level of AE patient care and an integer programming model is used to locate aircraft within the provider network. The high costs associated with operating current aircraft drive this research to look for solutions that better represent the future of Urgent and Priority patient movement operations whether CONUS or global
Microwave ISM Emission Observed by WMAP
We investigate the nature of the diffuse Galactic emission in the Wilkinson
Microwave Anisotropy Probe (WMAP) temperature anisotropy data. Substantial
dust-correlated emission is observed at all WMAP frequencies, far exceeding the
expected thermal dust emission in the lowest frequency channels (23, 33, 41
GHz). The WMAP team (Bennett et al.) interpret this emission as dust-correlated
synchrotron radiation, attributing the correlation to the natural association
of relativistic electrons produced by SNae with massive star formation in dusty
clouds, and deriving an upper limit of 5% on the contribution of Draine &
Lazarian spinning dust at K-band (23 GHz). We pursue an alternative
interpretation that much, perhaps most, of the dust-correlated emission at
these frequencies is indeed spinning dust, and explore the spectral dependence
on environment by considering a few specific objects as well as the full sky
average. Models similar to Draine & Lazarian spinning dust provide a good fit
to the full-sky data. The full-sky fit also requires a significant component
with free-free spectrum uncorrelated with \Halpha, possibly hot (~million K)
gas within 30 degrees of the Galactic center.Comment: ApJ in press (accepted 5 Dec 2003), version 2: corrected typos and
added references. 23 pages, 5 figures, 2 tables. Free-free haze map is
available at http://skymaps.inf
Evidence Of Dark Matter Annihilations In The WMAP Haze
The WMAP experiment has revealed an excess of microwave emission from the
region around the center of our Galaxy. It has been suggested that this signal,
known as the ``WMAP Haze'', could be synchrotron emission from relativistic
electrons and positrons generated in dark matter annihilations. In this letter,
we revisit this possibility. We find that the angular distribution of the WMAP
Haze matches the prediction for dark matter annihilations with a cusped density
profile, in the inner kiloparsecs. Comparing the
intensity in different WMAP frequency bands, we find that a wide range of
possible WIMP annihilation modes are consistent with the spectrum of the haze
for a WIMP with a mass in the 100 GeV to multi-TeV range. Most interestingly,
we find that to generate the observed intensity of the haze, the dark matter
annihilation cross section is required to be approximately equal to the value
needed for a thermal relic, cm/s. No
boost factors are required. If dark matter annihilations are in fact
responsible for the WMAP Haze, and the slope of the halo profile continues into
the inner Galaxy, GLAST is expected to detect gamma rays from the dark matter
annihilations in the Galactic Center if the WIMP mass is less than several
hundred GeV.Comment: 4 pages, 3 figure
Realizing Omega-regular Hyperproperties
We studied the hyperlogic HyperQPTL, which combines the concepts of trace
relations and -regularity. We showed that HyperQPTL is very expressive,
it can express properties like promptness, bounded waiting for a grant,
epistemic properties, and, in particular, any -regular property. Those
properties are not expressible in previously studied hyperlogics like HyperLTL.
At the same time, we argued that the expressiveness of HyperQPTL is optimal in
a sense that a more expressive logic for -regular hyperproperties would
have an undecidable model checking problem. We furthermore studied the
realizability problem of HyperQPTL. We showed that realizability is decidable
for HyperQPTL fragments that contain properties like promptness. But still, in
contrast to the satisfiability problem, propositional quantification does make
the realizability problem of hyperlogics harder. More specifically, the
HyperQPTL fragment of formulas with a universal-existential propositional
quantifier alternation followed by a single trace quantifier is undecidable in
general, even though the projection of the fragment to HyperLTL has a decidable
realizability problem. Lastly, we implemented the bounded synthesis problem for
HyperQPTL in the prototype tool BoSy. Using BoSy with HyperQPTL specifications,
we have been able to synthesize several resource arbiters. The synthesis
problem of non-linear-time hyperlogics is still open. For example, it is not
yet known how to synthesize systems from specifications given in branching-time
hyperlogics like HyperCTL.Comment: International Conference on Computer Aided Verification (CAV 2020
Microwave ISM Emission in the Green Bank Galactic Plane Survey: Evidence for Spinning Dust
We observe significant dust-correlated emission outside of H II regions in
the Green Bank Galactic Plane Survey (-4 < b < 4 degrees) at 8.35 and 14.35
GHz. The rising spectral slope rules out synchrotron and free-free emission as
majority constituents at 14 GHz, and the amplitude is at least 500 times higher
than expected thermal dust emission. When combined with the Rhodes (2.326 GHz),
and WMAP (23-94 GHz) data it is possible to fit dust-correlated emission at
2.3-94 GHz with only soft synchrotron, free-free, thermal dust, and an
additional dust-correlated component similar to Draine & Lazarian spinning
dust. The rising component generally dominates free-free and synchrotron for
\nu >~ 14 GHz and is overwhelmed by thermal dust at \nu > 60 GHz. The current
data fulfill most of the criteria laid out by Finkbeiner et al. (2002) for
detection of spinning dust.Comment: ApJ in press. 26 pages, 11 figures, figures jpeg compressed to save
spac
Pseudo-Dipole Signal Removal from WMAP Data
It is discovered in our previous work that different observational
systematics, e.g., errors of antenna pointing directions, asynchronous between
the attitude and science data, can generate pseudo-dipole signal in full-sky
maps of the cosmic microwave background (CMB) anisotropy published by The
Wilkinson Microwave Anisotropy Probe (WMAP) team. Now the antenna sidelobe
response to the Doppler signal is found to be able to produce similar effect as
well. In this work, independent to the sources, we uniformly model the
pseudo-dipole signal and remove it from published WMAP7 CMB maps by model
fitting. The result demonstrates that most of the released WMAP CMB quadrupole
is artificial.Comment: V3: using WMAP7 dat
A determination of the Spectra of Galactic components observed by WMAP
WMAP data when combined with ancillary data on free-free, synchrotron and
dust allow an improved understanding of the spectrum of emission from each of
these components. Here we examine the sky variation at intermediate latitudes
using a cross-correlation technique. In particular, we compare the observed
emission in 15 selected sky regions to three ``standard'' templates.
The free-free emission of the diffuse ionised gas is fitted by a well-known
spectrum at K and Ka band, but the derived emissivity corresponds to a mean
electron temperature of ~4000-5000K. This is inconsistent with estimates from
galactic HII regions. The origin of the discrepancy is unclear.
The anomalous emission associated with dust is clearly detected in most of
the 15 fields studied; it correlates well with the Finkbeiner et al. model 8
predictions (FDS8) at 94 GHz, with an effective spectral index between 20 and
60GHz of -2.85. Furthermore, the emissivity varies by a factor of ~2 from cloud
to cloud. A modestly improved fit to the anomalous dust at K-band is provided
by modulating the template by an estimate of the dust colour temperature,
specifically FDS8*T^n. We find a preferred value n~1.6.
The synchrotron emission steepens between GHz frequencies and the WMAP bands.
There are indications of spectral index variations across the sky but the
current data are not precise enough to accurately quantify this from region to
region. Our analysis of the WMAP data indicates strongly that the
dust-correlated emission at the low WMAP frequencies has a spectrum which is
compatible with spinning dust; we find no evidence for a synchrotron component
correlated with dust (abridged).Comment: 18 pages, 6 figures, revised version uses cross-correlation method
rather than T-T method. Paper re-organised and sent back to refere
A Limit on the Polarized Anomalous Microwave Emission of Lynds 1622
The dark cloud Lynds 1622 is one of a few specific sites in the Galaxy where,
relative to observed free-free and vibrational dust emission, there is a clear
excess of microwave emission. In order to constrain models for this microwave
emission, and to better establish the contribution which it might make to
ongoing and near-future microwave background polarization experiments, we have
used the Green Bank Telescope to search for linear polarization at 9.65 Ghz
towards Lynds 1622. We place a 95.4% upper limit of 88 micro-Kelvin (123
micro-Kelvin at 99.7 confidence) on the total linear polarization of this
source averaged over a 1'.3 FWHM beam. Relative to the observed level of
anomalous emission in Stokes I these limits correspond to fractional linear
polarizations of 2.7% and 3.5%.Comment: replaced with version accepted by Ap
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