1,350 research outputs found
Overcoming Barriers to the Use of Osteopathic Manipulation Techniques in the Emergency Department
Background: Osteopathic Manipulation Techniques (OMT) have been shown to be effective therapeutic modalities in various clinical settings, but appear to be underutilized in the emergency department (ED) setting.Objective: To examine barriers to the use of OMT in the ED and provide suggestions to ameliorate these barriers.Methods: Literature reviewResults: While the medical literature cites numerous obstacles to the use of OMT in the ED setting, most can be positively addressed through education, careful planning, and ongoing research into use of these techniques. Recent prospective clinical trials of OMT have demonstrated the utility of these modalities.Conclusion: Osteopathic Manipulation Techniques are useful therapeutic modalities that could be utilized to a greater degree in the ED. As the number of osteopathic emergency physicians increases, the opportunity to employ these techniques should increase.[WestJEM. 2009;10:184-189.
Lower Limits on Aperture Size for an ExoEarth-Detecting Coronagraphic Mission
The yield of Earth-like planets will likely be a primary science metric for
future space-based missions that will drive telescope aperture size. Maximizing
the exoEarth candidate yield is therefore critical to minimizing the required
aperture. Here we describe a method for exoEarth candidate yield maximization
that simultaneously optimizes, for the first time, the targets chosen for
observation, the number of visits to each target, the delay time between
visits, and the exposure time of every observation. This code calculates both
the detection time and multi-wavelength spectral characterization time required
for planets. We also refine the astrophysical assumptions used as inputs to
these calculations, relying on published estimates of planetary occurrence
rates as well as theoretical and observational constraints on terrestrial
planet sizes and classical habitable zones. Given these astrophysical
assumptions, optimistic telescope and instrument assumptions, and our new
completeness code that produces the highest yields to date, we suggest lower
limits on the aperture size required to detect and characterize a
statistically-motivated sample of exoEarths.Comment: Accepted for publication in ApJ; 38 pages, 16 Figures, 3 Table
Optical Coronagraphic Spectroscopy of AU Mic: Evidence of Time Variable Colors?
We present coronagraphic long slit spectra of AU Mic's debris disk taken with
the STIS instrument aboard the Hubble Space Telescope (HST). Our spectra are
the first spatially resolved, scattered light spectra of the system's disk,
which we detect at projected distances between approximately 10 and 45 AU. Our
spectra cover a wavelength range between 5200 and 10200 angstroms. We find that
the color of AU Mic's debris disk is bluest at small (12-35 AU) projected
separations. These results both confirm and quantify the findings qualitatively
noted by Krist et al. (2005), and are different than IR observations that
suggested a uniform blue or gray color as a function of projected separation in
this region of the disk. Unlike previous literature that reported the color of
AU Mic's disk became increasingly more blue as a function of projected
separation beyond approximately 30 AU, we find the disk's optical color between
35-45 AU to be uniformly blue on the southeast side of the disk and
decreasingly blue on the northwest side. We note that this apparent change in
disk color at larger projected separations coincides with several fast, outward
moving "features" that are passing through this region of the southeast side of
the disk. We speculate that these phenomenon might be related, and that the
fast moving features could be changing the localized distribution of sub-micron
sized grains as they pass by, thereby reducing the blue color of the disk in
the process. We encourage follow-up optical spectroscopic observations of the
AU Mic to both confirm this result, and search for further modifications of the
disk color caused by additional fast moving features propagating through the
disk.Comment: Accepted by AJ, 13 pages, 8 figures, 1 tabl
On the discretization of physical momenta in lattice QCD
The adoption of two distinct boundary conditions for two fermions species on
a finite lattice allows to deal with arbitrary relative momentum between the
two particle species, in spite of the momentum quantization rule due to a
limited physical box size. We test the physical significance of this
topological momentum by checking in the continuum limit the validity of the
expected energy-momentum dispersion relations.Comment: 9 pages, 3 figures; references added; no changes in text or results;
version accepted for pubblication in Phys. Lett.
The penetration of FUV radiation into molecular clouds
The solution of the FUV radiative transfer equation can be complicated if the
most relevant radiative processes such as dust scattering and gas line
absorption are included, and have realistic (non-uniform) properties. We have
extended the spherical harmonics method to solve for the FUV radiation field in
illuminated clouds taking into account gas absorption and coherent,
nonconservative and anisotropic scattering by dust grains. Our formalism allows
us to consistently include: (i) varying dust populations and (ii) gas lines in
the FUV radiative transfer. The FUV penetration depth rises for increasing dust
albedo and anisotropy of the scattered radiation (e.g. when grains grow towards
cloud interiors). Illustrative models of illuminated clouds where only the dust
populations are varied confirm earlier predictions for the FUV penetration in
diffuse clouds (A_V1) we show
that the FUV radiation field inside the cloud can differ by orders of magnitude
depending on the grain properties. We show that the photochemical and thermal
gradients can be very different depending on grain growth. Therefore, the
assumption of uniform dust properties and averaged extinction curves can be a
crude approximation to determine the resulting scattering properties,
prevailing chemistry and atomic/molecular abundances in ISM clouds or
protoplanetary disks.Comment: Accepted for publication in Astronomy & Astrophysics. Section 2.
Astrophysical processes. Version 2: minor language corrections added. Figs.
2, 4 and 8 bitmapped to lower resolutio
Origin of the anomalous Hall Effect in overdoped n-type cuprates: current vertex corrections due to antiferromagnetic fluctuations
The anomalous magneto-transport properties in electron doped (n-type)
cuprates were investigated using Hall measurements at THz frequencies. The
complex Hall angle was measured in overdoped PrCeCuO samples (x=0.17 and 0.18) as a continuous function of
temperature above at excitation energies 5.24 and 10.5 meV. The results,
extrapolated to low temperatures, show that inelastic scattering introduces
electron-like contributions to the Hall response. First principle calculations
of the Hall angle that include current vertex corrections (CVC) induced by
electron interactions mediated by magnetic fluctuations in the Hall
conductivity reproduce the temperature, frequency, and doping dependence of the
experimental data. These results show that CVC effects are the source of the
anomalous Hall transport properties in overdoped ntype cuprates.Comment: 5 pages, 3 figure
Observations of 51 Ophiuchi with MIDI at the VLTI
We present interferometric observations of the Be star 51 Ophiuchi. These
observations were obtained during the science demonstration phase of the MIDI
instrument at the Very Large Telescope Interferometer (VLTI). Using MIDI, a
Michelson 2 beam combiner that operates at the N band (8 to 13 microns), we
obtained for the first time observations of 51 Oph in the mid-infrared at
high-angular resolution. It is currently known that this object presents a
circumstellar dust and gas disk that shows a very different composition from
other Herbig Ae disks. The nature of the 51 Oph system is still a mystery to be
solved. Does it have a companion? Is it a protoplanetary system? We still don't
know. Observations with MIDI at the VLTI allowed us to reach high-angular
resolution (20 mas).We have several uv points that allowed us to constrain the
disk model. We have modeled 51 Oph visibilities and were able to constrain the
size and geometry of the 51 Oph circumstellar disk.Comment: 5 pages, 3 figures, 2 tables, to be published in the proceedings of
"The Power of Optical / IR Interferometry: Recent Scientific Results and 2nd
Generation VLTI Instrumentation", Garching, April 4-8, 200
The Exozodiacal Dust Problem for Direct Observations of ExoEarths
Debris dust in the habitable zones of stars - otherwise known as exozodiacal
dust - comes from extrasolar asteroids and comets and is thus an expected part
of a planetary system. Background flux from the Solar System's zodiacal dust
and the exozodiacal dust in the target system is likely to be the largest
source of astrophysical noise in direct observations of terrestrial planets in
the habitable zones of nearby stars. Furthermore, dust structures like clumps,
thought to be produced by dynamical interactions with exoplanets, are a
possible source of confusion. In this paper, we qualitatively assess the
primary impact of exozodical dust on high-contrast direct imaging at optical
wavelengths, such as would be performed with a coronagraph. Then we present the
sensitivity of previous, current, and near-term facilities to thermal emission
from debris dust at all distances from nearby solar-type stars, as well as our
current knowledge of dust levels from recent surveys. Finally, we address the
other method of detecting debris dust, through high-contrast imaging in
scattered light. This method is currently far less sensitive than thermal
emission observations, but provides high spatial resolution for studying dust
structures. This paper represents the first report of NASA's Exoplanet
Exploration Program Analysis Group (ExoPAG).Comment: 21 pages, 5 figures, 2 tables. Accepted for publication in PASP
2012-06-0
FUSE and HST STIS Observations of Hot and Cold Gas in the AB Aurigae System
We present the first observations of a Herbig Ae star with a circumstellar
disk by the Far Ultraviolet Spectroscopic Explorer (FUSE), as well as a
simultaneous observation of the star obtained with the Hubble Space Telescope
Space Telescope Imaging Spectrograph (STIS). The spectra of AB Aurigae show
emission and absorption features arising from gasses that have a wide range in
temperature, from hot OVI emission to cold molecular hydrogen and CO
absorption. Emissions from the highly ionized species OVI and CIII present in
the FUSE spectrum are redshifted, while absorption features arising from
low-ionization species like OI, NI, and SiII are blueshifted and show
characteristic stellar wind line-profiles. We find the total column density of
molecular hydrogen toward AB Aur from the FUSE apectrum, N(H_2) = (6.8 +/- 0.5)
x 10^19 cm^-2. The gas kinetic temperature of the molecular hydrogen derived
from the ratio N(J=1)/N(J=0) is 65 +/- 4 K. The column density of the CO
observed in the STIS spectrum is N(CO) = (7.1 +/- 0.5) x 10^13 cm^-2, giving a
CO/H_2 ratio of (1.04 +/- 0.11) x 10^-6. We also use the STIS spectrum to find
the column density of HI, permitting us to calculate the total column density
of hydrogen atoms, the fractional abundance of H_2, and the gas-to-dust ratio.Comment: 5 pages, including 6 figures. LaTex2e (emulateapj5.sty). Accepted for
publication in ApJ Letter
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