28,000 research outputs found
Thoracic epidural anaesthesia impairs the hemodynamic response to acute pulmonary hypertension by depressing right ventricular contractility in pigs
Evaluation and Management of Sleep Disorders in the Hand Surgery Patient.
Despite posing a significant public health threat, sleep disorders remain poorly understood and often underdiagnosed and mismanaged. Although sleep disorders are seemingly unrelated, hand surgeons should be mindful of these because numerous conditions of the upper extremity have known associations with sleep disturbances that can adversely affect patient function and satisfaction. In addition, patients with sleep disorders are at significantly higher risk for severe, even life-threatening medical comorbidities, further amplifying the role of hand surgeons in the recognition of this condition
U(1) Gauge Theory of the Hubbard Model : Spin Liquid States and Possible Application to k-(BEDT-TTF)_2 Cu_2 (CN)_3
We formulate a U(1) gauge theory of the Hubbard model in the slave-rotor
representation. From this formalism it is argued that spin liquid phases may
exist near the Mott transition in the Hubbard model on triangular and honeycomb
lattices at half filling. The organic compound k-(BEDT-TTF)_2 Cu_2 (CN)_3 is a
good candidate for the spin liquid state on a triangular lattice. We predict a
highly unusual temperature dependence for the thermal conductivity of this
material.Comment: 5 pages, 2 figures; paper shortened and the phase diagram of
anisotropic triangular lattice correcte
A Deep Multicolor Survey V: The M Dwarf Luminosity Function
We present a study of M dwarfs discovered in a large area, multicolor survey.
We employ a combination of morphological and color criteria to select M dwarfs
to a limiting magnitude in V of 22, the deepest such ground-based survey for M
dwarfs to date. We solve for the vertical disk stellar density law and use the
resulting parameters to derive the M dwarf luminosity and mass functions from
this sample. We find the stellar luminosity function peaks at M_V = 12 and
declines thereafter. Our derived mass function for stars with M < 0.6 M_sun is
inconsistent with a Salpeter function at the 3 sigma level; instead, we find
the mass function is relatively flat for 0.6 M_sun > M > 0.1 M_sun.Comment: Accepted for publication in AJ. 19 pages including 4 embedded
postscript figures (AASTEX
Emergence of coherence in the Mott--superfluid quench of the Bose-Hubbard model
We study the quench from the Mott to the superfluid phase in the Bose-Hubbard
model and investigate the spatial-temporal growth of phase coherence, i.e.,
phase locking between initially uncorrelated sites. To this end, we establish a
hierarchy of correlations via a controlled expansion into inverse powers of the
coordination number . It turns out that the off-diagonal long-range order
spreads with a constant propagation speed, forming local condensate patches,
whereas the phase correlator follows a diffusion-like growth rate.Comment: 4 page
Revealing New Physical Structures in the Supernova Remnant N63A through Chandra Imaging Spectroscopy
We present Chandra X-ray observations of the supernova remnant (SNR) N63A in
the Large Magellanic Cloud (LMC). N63A, one of the brightest LMC remnants, is
embedded in an H II region and probably associated with an OB association. The
optical remnant consists of three lobes of emission contained within the
approximately three times larger X-ray remnant. Our Chandra data reveal a
number of new physical structures in N63A. The most striking of these are the
several ``crescent''-shaped structures located beyond the main shell that
resemble similar features seen in the Vela SNR. In Vela, these have been
interpreted as arising from high speed clumps of supernova ejecta interacting
with the ambient medium. Another distinct feature of the remnant is a roughly
triangular ``hole'' in the X-ray emission near the location of the optical
lobes and the brightest radio emission. X-ray spectral analysis shows that this
deficit of emission is a result of absorption by an intervening dense cloud
with a mass of ~450 M_sun that is currently being engulfed by the remnant's
blast wave. We also find that the rim of the remnant, as well as the
crescent-shaped features, have considerably softer X-ray spectra than the
interior. Limits on hard X-ray emission rule out a young, energetic pulsar in
N63A, but the presence of an older or less active one, powering a wind nebula
with a luminosity less than ~4e10^34 erg/s, is allowed.Comment: 18 pages, 5 figures (2 color), accepted for publication in Ap
An ASCA Study of the High Luminosity SNR G349.7+0.2
We present ASCA observations of supernova remnant (SNR) G349.7+0.2. The
remnant has an irregular shell morphology and is interacting with a molecular
cloud, evident from the presence of OH(1720 MHz) masers and shocked molecular
gas. The X-ray morphology is consistent with that at radio wavelengths, with a
distinct enhancement in the south. The X-ray emission from the SNR is well
described by a model of a thermal plasma which has yet to reach ionization
equilibrium. The hydrogen column of ~6.0 X 10^{22} cm^{-2} is consistent with
the large distance to the remnant of ~22 kpc estimated from the maser
velocities. We derive an X-ray luminosity of L_x(0.5-10.0 keV)= 1.8 X 10^{37}
d_{22}^2 erg/s, which makes G349.7+0.2 one of the most X-ray luminous
shell-type SNRs known in the Galaxy. The age of the remnant is estimated to be
about 2800 yrs. The ambient density and pressure conditions appear similar to
those inferred for luminous compact SNRs found in starburst regions of other
galaxies, and provides support for the notion that these may be the result of
SNR evolution in the vicinity of dense molecular clouds.Comment: 5 pages, 3 figures. Accepted for publication in Ap
Large-scale Correlation of Mass and Galaxies with the Lyman-alpha Forest Transmitted Flux
We present predictions of the correlation between the Lyman-alpha forest
absorption in quasar spectra and the mass within \sim 5 Mpc/h (comoving) of the
line of sight, using fully hydrodynamic and hydro-PM numerical simulations of
the cold dark matter model supported by present observations. The observed
correlation based on galaxies and the Lya forest can be directly compared to
our theoretical results, assuming that galaxies are linearly biased on large
scales. Specifically, we predict the average value of the mass fluctuation,
, conditioned to a fixed value of the Lya forest transmitted flux
delta_F, after they have been smoothed over a 10 Mpc/h cube and line of sight
interval, respectively. We find that /sigma_m as a function of
delta_F/sigma_F has a slope of 0.6 at this smoothing scale, where sigma_m and
sigma_F are the rms dispersions (this slope should decrease with the smoothing
scale). We show that this value is largely insensitive to the cosmological
model and other Lya forest parameters. Comparison of our predictions to
observations should provide a fundamental test of our ideas on the nature of
the Lya forest and the distribution of galaxies, and can yield a measurement of
the bias factor of any type of galaxies that are observed in the vicinity of
Lya forest lines of sight.Comment: Submitted to ApJ, 41 page
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