775 research outputs found
Effects of hydrogen on the morphology and electrical properties of GaN grown by plasma-assisted molecular-beam epitaxy
We study the effect of introducing hydrogen gas through the rf-plasma source during plasma-assisted molecular-beam epitaxy of GaN(0001). The well-known smooth-to-rough transition that occurs for this surface as a function of decreasing Ga flux in the absence of H is found to persist even with H present, although the critical Ga flux for this transition increases. Under Ga-rich conditions, the presence of hydrogen is found to induce step bunching (facetting) on the surface. Conductive atomic force microscopy reveals that leakage current through dislocation cores is significantly reduced when hydrogen is present during the growth
Numerical analysis and experimental study of the error of magnetic field strength measurements with single sheet testers
The error of the measurement of the magnetic field strength with a single sheet tester has been studied. Two different methods, determination by means of field sensing coils (1) and from the magnetizing current (2), have been compared. The errors of methods(1) and (2) were calculated by the finite element method (FEM), different parameters having been varied, and method (2) was additionally studied experimentally. SSTs with wound yokes and stacked yokes were considered. The results will help to decide whether the more complicated and more accurate H coil method or the easier to handle, but less accurate m.c.method is chosen.</p
OnabotulinumtoxinA 100U provides significant improvements in overactive bladder symptoms in patients with urinary incontinence regardless of the number of anticholinergic therapies used or reason for inadequate management of overactive bladder
INTRODUCTION: A prespecified pooled analysis of two placebo-controlled, phase 3 trials evaluated whether the number of prior anticholinergics used or reason for their discontinuation affected the treatment response to onabotulinumtoxinA 100U in overactive bladder (OAB) patients with urinary incontinence (UI). METHODS: Patients with symptoms of OAB received intradetrusor injections of onabotulinumtoxinA 100U or placebo, sparing the trigone. Change from baseline at week 12 in UI episodes/day, proportion of patients reporting a positive response (‘greatly improved’ or ‘improved’) on the treatment benefit scale (TBS), micturition and urgency were evaluated by number of prior anticholinergics (1, 2 or ≥ 3) and reason for their discontinuation (insufficient efficacy or side effects). Adverse events (AE) were assessed. RESULTS: Patients had taken an average of 2.4 anticholinergics before study enrolment. OnabotulinumtoxinA reduced UI episodes/day from baseline vs. placebo, regardless of the number of prior anticholinergics (−2.82 vs. −1.52 for one prior anticholinergic; −2.58 vs. −0.58 for two prior anticholinergics; and −2.92 vs. −0.73 for three or more prior anticholinergics; all p < 0.001). The proportion of TBS responders was higher with onabotulinumtoxinA vs. placebo (69.0% vs. 37.2% for one prior anticholinergic; 58.8% vs. 24.8% for two prior anticholinergics and 56.4% vs. 22.5% for three or more prior anticholinergics; all p < 0.001). Similar results were observed regardless of the reason for discontinuation. OnabotulinumtoxinA reduced the episodes of urgency and frequency of micturition vs. placebo in all groups. AEs were well tolerated, with a comparable incidence in all groups. CONCLUSION: In patients with symptoms of OAB who were inadequately managed by one or more anticholinergics, onabotulinumtoxinA 100U provided significant and similar treatment benefit and safety profile regardless of the number of prior anticholinergics used or reason for inadequate management of OAB. ClinicalTrials.gov: NCT00910845, NCT00910520
A biophysical model of prokaryotic diversity in geothermal hot springs
Recent field investigations of photosynthetic bacteria living in geothermal
hot spring environments have revealed surprisingly complex ecosystems, with an
unexpected level of genetic diversity. One case of particular interest involves
the distribution along hot spring thermal gradients of genetically distinct
bacterial strains that differ in their preferred temperatures for reproduction
and photosynthesis. In such systems, a single variable, temperature, defines
the relevant environmental variation. In spite of this, each region along the
thermal gradient exhibits multiple strains of photosynthetic bacteria adapted
to several distinct thermal optima, rather than the expected single thermal
strain adapted to the local environmental temperature. Here we analyze
microbiology data from several ecological studies to show that the thermal
distribution field data exhibit several universal features independent of
location and specific bacterial strain. These include the distribution of
optimal temperatures of different thermal strains and the functional dependence
of the net population density on temperature. Further, we present a simple
population dynamics model of these systems that is highly constrained by
biophysical data and by physical features of the environment. This model can
explain in detail the observed diversity of different strains of the
photosynthetic bacteria. It also reproduces the observed thermal population
distributions, as well as certain features of population dynamics observed in
laboratory studies of the same organisms
A New Mechanism for Generating a Single Transverse Spin Asymmetry
We propose a new mechanism for generating a single transverse spin asymmetry
(STSA) in polarized proton-proton and proton-nucleus collisions in the
high-energy scattering approximation. In this framework the STSA originates
from the q->q G splitting in the projectile (proton) light-cone wave function
followed by a perturbative (C-odd) odderon interaction, together with a C-even
interaction, between the projectile and the target. We show that some aspects
of the obtained expression for the STSA of the produced quarks are in
qualitative agreement with experiment: STSA decreases with decreasing
projectile x_F and is a non-monotonic function of the transverse momentum k_T.
In our framework the STSA peaks at k_T near the saturation scale Q_s. Our
mechanism predicts that the quark STSA in proton-nucleus collisions should be
much smaller than in proton-proton collisions. We also observe that in our
formalism the STSA for prompt photons is zero.Comment: 28 pages, 17 figues; v2: minor corrections, a subsection, discussion
and references added; v3: minor corrections and a new figure added; v4: minor
corrections; v5: minor corrections in figure
Characterization of an autotrophic sulfide-oxidizing marine Arcobacter sp. that produces filamentous sulfur
Author Posting. © American Society for Microbiology, 2002. This article is posted here by permission of American Society for Microbiology for personal use, not for redistribution. The definitive version was published in Applied and Environmental Microbiology 68 (2002): 316-325, doi:10.1128/AEM.68.1.316-325.2002.A coastal marine sulfide-oxidizing autotrophic bacterium produces hydrophilic filamentous sulfur as a novel metabolic end product. Phylogenetic analysis placed the organism in the genus Arcobacter in the epsilon subdivision of the Proteobacteria. This motile vibrioid organism can be considered difficult to grow, preferring to grow under microaerophilic conditions in flowing systems in which a sulfide-oxygen gradient has been established. Purified cell cultures were maintained by using this approach. Essentially all 4',6-diamidino-2-phenylindole dihydrochloride-stained cells in a flowing reactor system hybridized with Arcobacter-specific probes as well as with a probe specific for the sequence obtained from reactor-grown cells. The proposed provisional name for the coastal isolate is "Candidatus Arcobacter sulfidicus." For cells cultured in a flowing reactor system, the sulfide optimum was higher than and the CO2 fixation activity was as high as or higher than those reported for other sulfur oxidizers, such as Thiomicrospira spp. Cells associated with filamentous sulfur material demonstrated nitrogen fixation capability. No ribulose 1,5-bisphosphate carboxylase/oxygenase could be detected on the basis of radioisotopic activity or by Western blotting techniques, suggesting an alternative pathway of CO2 fixation. The process of microbial filamentous sulfur formation has been documented in a number of marine environments where both sulfide and oxygen are available. Filamentous sulfur formation by "Candidatus Arcobacter sulfidicus" or similar strains may be an ecologically important process, contributing significantly to primary production in such environments.This work was supported by National Science Foundation grant
IBN-9630054
Communicating Josephson Qubits
We propose a scheme to implement a quantum information transfer protocol with
a superconducting circuit and Josephson charge qubits. The information exchange
is mediated by an L-C resonator used as a data bus. The main decoherence
sources are analyzed in detail.Comment: 4 pages, 2 figure
Bridging the data gaps in the epidemiology of hepatitis C virus infection in Malaysia using multi-parameter evidence synthesis
BACKGROUND: Collecting adequate information on key epidemiological indicators is a prerequisite to informing a public health response to reduce the impact of hepatitis C virus (HCV) infection in Malaysia. Our goal was to overcome the acute data shortage typical of low/middle income countries using statistical modelling to estimate the national HCV prevalence and the distribution over transmission pathways as of the end of 2009. METHODS: Multi-parameter evidence synthesis methods were applied to combine all available relevant data sources - both direct and indirect - that inform the epidemiological parameters of interest. RESULTS: An estimated 454,000 (95% credible interval [CrI]: 392,000 to 535,000) HCV antibody-positive individuals were living in Malaysia in 2009; this represents 2.5% (95% CrI: 2.2-3.0%) of the population aged 15-64 years. Among males of Malay ethnicity, for 77% (95% CrI: 69-85%) the route of probable transmission was active or a previous history of injecting drugs. The corresponding proportions were smaller for male Chinese and Indian/other ethnic groups (40% and 71%, respectively). The estimated prevalence in females of all ethnicities was 1% (95% CrI: 0.6 to 1.4%); 92% (95% CrI: 88 to 95%) of infections were attributable to non-drug injecting routes of transmission. CONCLUSIONS: The prevalent number of persons living with HCV infection in Malaysia is estimated to be very high. Low/middle income countries often lack a comprehensive evidence base; however, evidence synthesis methods can assist in filling the data gaps required for the development of effective policy to address the future public health and economic burden due to HCV. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12879-014-0564-6) contains supplementary material, which is available to authorized users
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