7,848 research outputs found
Reporting participation rates in studies of non-pharmacological interventions for patients with chronic obstructive pulmonary disease: a systematic review
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited
Development of a bedrest muscle stress apparatus
In attempting further to define the deleterious effects of spaceflight on the human body, measurement systems and techniques were devised to determine the loss of skeletal muscle strength and tone as a result of spaceflight exposure. In order to determine how the muscle degradation process progresses with time during nonuse, a system for measuring muscle stress during bedrest was developed. The Bedrest Muscle Stress Apparatus is configured to slip snugly over the foot board of a standard hospital bed. Data collected with this device correlated well with pre- and post-bedrest data collected with the original skeletal muscle stress apparatus
Towards low-latency real-time detection of gravitational waves from compact binary coalescences in the era of advanced detectors
Electromagnetic (EM) follow-up observations of gravitational wave (GW) events
will help shed light on the nature of the sources, and more can be learned if
the EM follow-ups can start as soon as the GW event becomes observable. In this
paper, we propose a computationally efficient time-domain algorithm capable of
detecting gravitational waves (GWs) from coalescing binaries of compact objects
with nearly zero time delay. In case when the signal is strong enough, our
algorithm also has the flexibility to trigger EM observation before the merger.
The key to the efficiency of our algorithm arises from the use of chains of
so-called Infinite Impulse Response (IIR) filters, which filter time-series
data recursively. Computational cost is further reduced by a template
interpolation technique that requires filtering to be done only for a much
coarser template bank than otherwise required to sufficiently recover optimal
signal-to-noise ratio. Towards future detectors with sensitivity extending to
lower frequencies, our algorithm's computational cost is shown to increase
rather insignificantly compared to the conventional time-domain correlation
method. Moreover, at latencies of less than hundreds to thousands of seconds,
this method is expected to be computationally more efficient than the
straightforward frequency-domain method.Comment: 19 pages, 6 figures, for PR
Analytical and experimental study of the dynamics of a single-tube counterflow boiler
Experimental and analytical study of dynamics of single tube counterflow boile
High-Energy Neutrino Signatures of Dark Matter Decaying into Leptons
Decaying dark matter has previously been proposed as a possible explanation
for the excess high energy cosmic ray electrons and positrons seen by PAMELA
and the Fermi Gamma-Ray Space Telescope (FGST). To accommodate these signals
however, the decays must be predominantly leptonic, to muons or taus, and
therefore produce neutrinos, potentially detectable with the IceCube neutrino
observatory. We find that, with five years of data, IceCube (supplemented by
DeepCore) will be able to significantly constrain the relevant parameter space
of decaying dark matter, and may even be capable of discovering dark matter
decaying in the halo of the Milky Way.Comment: 4 pages, 1 figur
Neutrophil gelatinase-associated lipocalin: its response to hypoxia and association with acute mountain sickness.
Acute Mountain Sickness (AMS) is a common clinical challenge at high altitude (HA). A point-of-care biochemical marker for AMS could have widespread utility. Neutrophil gelatinase-associated lipocalin (NGAL) rises in response to renal injury, inflammation and oxidative stress. We investigated whether NGAL rises with HA and if this rise was related to AMS, hypoxia or exercise. NGAL was assayed in a cohort (n = 22) undertaking 6 hours exercise at near sea-level (SL); a cohort (n = 14) during 3 hours of normobaric hypoxia (FiO2 11.6%) and on two trekking expeditions (n = 52) to over 5000 m. NGAL did not change with exercise at SL or following normobaric hypoxia. During the trekking expeditions NGAL levels (ng/ml, mean ± sd, range) rose significantly (P < 0.001) from 68 ± 14 (60-102) at 1300 m to 183 ± 107 (65-519); 143 ± 66 (60-315) and 150 ± 71 (60-357) at 3400 m, 4270 m and 5150 m respectively. At 5150 m there was a significant difference in NGAL between those with severe AMS (n = 7), mild AMS (n = 16) or no AMS (n = 23): 201 ± 34 versus 171 ± 19 versus 124 ± 12 respectively (P = 0.009 for severe versus no AMS; P = 0.026 for mild versus no AMS). In summary, NGAL rises in response to prolonged hypobaric hypoxia and demonstrates a relationship to the presence and severity of AMS
Light emission through a corrugated metal film: The role of cross-coupled surface plasmon polaritons
S. Wedge, Ian R. Hooper, I. Sage, and William L. Barnes, Physical Review B, Vol. 69, article 245418 (2004). "Copyright © 2004 by the American Physical Society."We examine the phenomenon of light emission through a thin metal film that takes place via surface plasmon polaritons. Surface plasmon polariton cross coupling has recently been invoked to explain sharp features observed in the angle dependent emission spectra obtained from surface-emitting (through cathode) organic light-emitting diode structures. We investigated whether such a cross-coupling process is needed to explain such observations. We undertook measurements on samples for a variety of metal film thicknesses. Our results are consistent with the mechanism of surface plasmon polariton cross coupling but also show that the processes underlying the emission from such structures can be rather subtle
Non-Thermal Dark Matter Mimicking An Additional Neutrino Species In The Early Universe
The South Pole Telescope (SPT), Atacama Cosmology Telescope (ACT), and
Wilkinson Microwave Anisotropy Probe (WMAP) have each reported measurements of
the cosmic microwave background's (CMB) angular power spectrum which favor the
existence of roughly one additional neutrino species, in addition to the three
contained in the standard model of particle physics. Neutrinos influence the
CMB by contributing to the radiation density, which alters the expansion rate
of the universe during the epoch leading up to recombination. In this paper, we
consider an alternative possibility that the excess kinetic energy implied by
these measurements was possessed by dark matter particles that were produced
through a non-thermal mechanism, such as late-time decays. In particular, we
find that if a small fraction (<1%) of the dark matter in the universe today
were produced through the decays of a heavy and relatively long-lived state,
the expansion history of the universe can be indistinguishable from that
predicted in the standard cosmological model with an additional neutrino.
Furthermore, if these decays take place after the completion of big bang
nucleosynthesis, this scenario can avoid tension with the value of three
neutrino species preferred by measurements of the light element abundances.Comment: 5 pages, 2 figure
Why Compact Tori For Fusion?
A compact torus (CT) has a toroidal magnetic and plasma geometry, but is contained within a simply-connected vacuum vessel such as a cylinder. Spheromaks and field-reversed configurations fall into this category. Compact tori are translatable and have a high engineering beta. The primary benefit of CTs for fusion is the absence of toroidal field and Ohmic Heating coils and the many problems brought on by them. Studying fusion-relevant plasma in simply-connected geometries affords the world fusion program both physics and technology opportunities not found in other configurations. This paper outlines the technology and physics opportunities of compact tori, and presents a cost model based on geometry for comparison with less compact configurations
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