1,141 research outputs found
The Effect of the Environment on alpha-Al_2O_3 (0001) Surface Structures
We report that calculating the Gibbs free energy of the alpha-Al_2O_3 (0001)
surfaces in equilibrium with a realistic environment containing both oxygen and
hydrogen species is essential for obtaining theoretical predictions consistent
with experimental observations. Using density-functional theory we find that
even under conditions of high oxygen partial pressure, the metal terminated
surface is surprisingly stable. An oxygen terminated alpha-Al_2O_3 (0001)
surface becomes stable only if hydrogen is present on the surface. In addition,
including hydrogen on the surface resolves discrepancies between previous
theoretical work and experimental results with respect to the magnitude and
direction of surface relaxations.Comment: 4 pages including 2 figures. Submitted to Phys. Rev. Lett. Related
publications can be found at http://www.fhi-berlin.mpg.de/th/paper.htm
Stochastic analysis of surface roughness
For the characterization of surface height profiles we present a new
stochastic approach which is based on the theory of Markov processes. With this
analysis we achieve a characterization of the complexity of the surface
roughness by means of a Fokker-Planck or Langevin equation, providing the
complete stochastic information of multiscale joint probabilities. The method
was applied to different road surface profiles which were measured with high
resolution. Evidence of Markov properties is shown. Estimations for the
parameters of the Fokker-Planck equation are based on pure, parameter free data
analysis
Activation mechanism of rabbit skeletal muscle myosin light chain kinase 5′-p-Fluorosulfonylbenzoyl adenosine as a probe of the MgATP-binding site of the calmodulin-bound and calmodulin-free enzyme
Abstract5′-p-Fluorosulfonylbenzoyl adenosine (FSBA), an ATP-like affinity labelling reagent, reacted with rabbit skeletal muscle myosin light chain kinase (skMLCK) and its calmodulin complex in a site-specific manner. Reaction was dependent upon the presence of the adenosine moiety of FSBA, saturated with increasing FSBA, was inhibited by MgATP, and was accompanied by stoichiometric incorporation of [14C]FSBA. The kinetic constants describing the reaction were similar for skMLCK and its calmodulin complex: k3= −0.040 min−1 and −0.038 mint-1, and Ki=0.18 mM and 0.40 mM, respectively. It is concluded that the MgATP-binding site on skMLCK remains accessible at all times and maintains a near constant conformation
Cost Utility of Omalizumab Compared with Standard of Care for the Treatment of Chronic Spontaneous Urticaria.
BACKGROUND: Chronic spontaneous urticaria (CSU) negatively impacts patient quality of life and productivity and is associated with considerable indirect costs to society. OBJECTIVE: The aim of this study was to assess the cost utility of add-on omalizumab treatment compared with standard of care (SOC) in moderate or severe CSU patients with inadequate response to SOC, from the UK societal perspective. METHODS: A Markov model was developed, consisting of health states based on Urticaria Activity Score over 7 days (UAS7) and additional states for relapse, spontaneous remission and death. Model cycle length was 4 weeks, and total model time horizon was 20 years in the base case. The model considered early discontinuation of non-responders (response: UAS7 ≤6) and retreatment upon relapse (relapse: UAS7 ≥16) for responders. Clinical and cost inputs were derived from omalizumab trials and published sources, and cost utility was expressed as incremental cost-effectiveness ratios (ICERs). Scenario analyses included no early discontinuation of non-responders and an altered definition of response (UAS7 <16). RESULTS: With a deterministic ICER of £3183 in the base case, omalizumab was associated with increased costs and benefits relative to SOC. Probabilistic sensitivity analysis supported this result. Productivity inputs were key model drivers, and individual scenarios without early discontinuation of non-responders and adjusted response definitions had little impact on results. ICERs were generally robust to changes in key model parameters and inputs. CONCLUSIONS: In this, the first economic evaluation of omalizumab in CSU from a UK societal perspective, omalizumab consistently represented a treatment option with societal benefit for CSU in the UK across a range of scenarios
A Spatially Resolved `Inside-out' Outburst of IP Pegasi
We present a comprehensive photometric dataset taken over the entire outburst
of the eclipsing dwarf nova IP Peg in September/October 1997. Analysis of the
lightcurves taken over the long rise to the peak-of-outburst shows conclusively
that the outburst started near the centre of the disc and moved outwards. This
is the first dataset that spatially resolves such an outburst. The dataset is
consistent with the idea that long rise times are indicative of such
`inside-out' outbursts. We show how the thickness and the radius of the disc,
along with the mass transfer rate change over the whole outburst. In addition,
we show evidence of the secondary and the irradiation thereof. We discuss the
possibility of spiral shocks in the disc; however we find no conclusive
evidence of their existence in this dataset.Comment: 8 pages, 8 figures, to be appear in MNRA
Modeling the impact of sea-spray on particle concentrations in a coastal city
Abstract 18 An atmospheric chemistry-transport model is used to assess the impacts of sea-spray chemistry 19 on the particle composition in and downwind of a coastal city -Vancouver, British Columbia. 20 Reactions in/on sea-spray affect the entire particle ensemble and particularly the size distribution 21 of particle nitrate. 2
Mechanical Percussion Devices: A Survey of Practice Patterns Among Healthcare Professionals
# Background
Mechanical percussion devices have become popular among sports medicine professionals. These devices provide a similar effect as manual percussion or tapotement used in therapeutic massage. To date, there are few published studies or evidence-based guidelines for these devices. There is a need to understand what professionals believe about this technology and how they use these devices in clinical practice.
# Purpose
To survey and document the knowledge, clinical application methods, and use of mechanical percussion devices among healthcare professionals in the United States.
# Design
Cross-sectional survey study.
# Methods
A 25 question online survey was emailed to members of the National Athletic Trainers Association, Academy of Orthopedic Physical Therapy, and American Academy of Sports Physical Therapy.
# Results
Four hundred twenty-five professionals completed the survey. Most professionals (92%, n=391) used devices from two manufacturers: Hyperice® and Theragun®. Seventy-seven percent directed clients to manufacturer and generic websites (n=329) to purchase devices. Most respondents used a medium and low device speed setting for pre- and post-exercise (62%, n=185), pain modulation (59%, n=253), and myofascial mobility (52%, n=222). A large proportion of respondents preferred a total treatment time between 30 seconds and three minutes (36-48%, n=153-204) or three to five minutes (18-22%, n=76-93). Most respondents (54-69%, n=229-293) believed that mechanical percussion increases local blood flow, modulates pain, enhances myofascial mobility, and reduces myofascial restrictions. Most respondents (72%, n=305) were influenced by other colleagues to use these devices. Sixty-six percent used patient reported outcomes (n=280) to document treatment efficacy. Live instruction was the most common mode of education (79%, n=334).
# Conclusion
These results are a starting point for future research and provide insight into how professionals use mechanical percussion devices. This survey also highlights the existing gap between research and practice. Future research should examine the efficacy of this technology and determine consensus-based guidelines.
# Level of Evidence
Ecological Consequences of Anomalies in Atmospheric Moisture and Snowpack
Although increased frequency of extreme‐weather events is one of the most secure predictions associated with contemporary climate change, effects of such events on distribution and abundance of climate‐sensitive species remain poorly understood. Montane ecosystems may be especially sensitive to extreme weather because of complex abiotic and biotic interactions that propagate from climate‐driven reductions in snowpack. Snowpack not only protects subnivean biotas from extreme cold, but also influences forage availability through timing of melt‐off and water availability. We related relative abundances of an alpine mammal, the American pika (Ochotona princeps), to measures of weather and snowpack dynamics over an 8‐yr period that included before and after a year of record‐low snowpack in Washington, USA. We sought to (1) quantify any change in pika abundance associated with the snowpack anomaly and (2) identify aspects of weather and snowpack that influenced abundance of pikas. Pikas showed a 1‐yr lag response to the snowpack anomaly and exhibited marked declines in abundance at elevations below 1,400 m simultaneous with increased abundances at higher elevations. Atmospheric moisture, indexed by vapor pressure deficit (VPD), was especially important, evidenced by strong support for the top‐ranked model that included the interaction of VPD with snowpack duration. Notably, our novel application of VPD from gridded climate data for analyses of animal abundances shows strong potential for improving species distribution models because VPD represents an important aspect of weather that influences the physiology and habitat of biota. Pikas were apparently affected by cold stress without snowpack at mid elevations, whereas changes to forage associated with snowpack and VPD were influential at high and low elevations. Our results reveal context dependency in pika responses to weather and illustrate how snow drought can lead to rapid change in the abundance of subnivean animals
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Modeling the impact of sea-spray on particle concentrations in a coastal city
An atmospheric chemistry-transport model is used to assess the impacts of sea-spray chemistry on the particle composition in and downwind of a coastal city--Vancouver, British Columbia. Reactions in/on sea-spray affect the entire particle ensemble and particularly the size distribution of particle nitrate. Urban air quality, and particularly airborne particles, is a major concern in terms of human health impacts. Sea-spray is known to be a major component of the particle ensemble at coastal sites yet relatively few air quality models include the interaction of gases with sea-spray and the fate of the particles produced. Sea-spray is not an inert addition to the particle ensemble because heterogeneous chemistry in/on sea-spray droplets changes the droplets composition and the particle size distribution, which impacts deposition and the ion balance in different particle size fractions. It is shown that the ISOPART model is capable of simulating gas and particle concentrations in the coastal metropolis of Vancouver and the surrounding valley. It is also demonstrated that to accurately simulate ambient concentrations of particles and reactive/soluble gases in a coastal valley it is absolutely critical to include heterogeneous chemistry in/on sea-spray. Partitioning of total particle-NO{sub 3}{sup -} between sea-spray and NH{sub 4}NO{sub 3} is highly sensitive to the amount of sea-spray present, and hence the initial vertical profile, sea-spray source functions [48] and the wind speed. When a fixed wind speed is used to initialize the sea-spray vertical profiles, as expected, the sea-spray concentration decays with distance inland, but the particle-NO{sub 3}{sup -} concentration decays more slowly because it is also a function of the uptake rate for HNO{sub 3}. The simulation results imply model analyses of air quality in coastal cities conducted without inclusion of sea-spray interactions may yield highly misleading results in terms of emission sensitivities of the PM size distribution. The sensitivity of the model results to the initial sea spray profile further suggests there would be great benefit in better definition of the vertical profile of size resolved sea-spray for use in such model studies
Circulating β-endorphin, adrenocorticotrophic hormone and cortisol levels of stallions before and after short road transport: stress effect of different distances
<p>Abstract</p> <p>Background</p> <p>Since transport evokes physiological adjustments that include endocrine responses, the objective of this study was to examine the responses of circulating β-endorphin, adrenocorticotrophic hormone (ACTH) and cortisol levels to transport stress in stallions.</p> <p>Methods</p> <p>Forty-two healthy Thoroughbred and crossbred stallions were studied before and after road transport over distances of 100, 200 and 300 km. Blood samples were collected from the jugular vein: first in a single box immediately before loading (pre-samples), then immediately after transport and unloading on arrival at the breeding stations (post-samples).</p> <p>Results</p> <p>An increase in circulating β-endorphin levels after transport of 100 km (<it>P </it>< 0.01), compared to basal values was observed. Circulating ACTH levels showed significant increases after transport of 100 km (<it>P </it>< 0.001) and 200 km (<it>P </it>< 0.001). Circulating cortisol levels showed significant increases after road transport over distances of 100, 200 and 300 km (<it>P </it>< 0.001). An effect of transport on β-endorphin, ACTH and cortisol variations was therefore evident for the different distances studied. No significant differences (<it>P </it>> 0.05) between horses of different ages and different breeds were observed for β-endorphin, ACTH and cortisol levels.</p> <p>Conclusion</p> <p>The results obtained for short term transportation of stallions showed a very strong reaction of the adrenocortical system. The lack of response of β-endorphin after transport of 200–300 km and of ACTH after transport of 300 km seems to suggest a soothing effect of negative feedback of ACTH and cortisol levels.</p
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