6,265 research outputs found
Plasma Electron Beam Welder for Space Vehicles Final Report
Feasibility of developing plasma electron beam welding system for earth orbiting vehicl
Cloning and sequence analysis of cDNAs encoding the cytosolic precursors of subunits GapA and GapB of chloroplast glyceraldehyde-3-phosphate dehydrogenase from pea and spinach
Chloroplast glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is composed of two different subunits, GapA and GapB. cDNA clones containing the entire coding sequences of the cytosolic precursors for GapA from pea and for GapB from pea and spinach have been identified, sequenced and the derived amino acid sequences have been compared to the corresponding sequences from tobacco, maize and mustard. These comparisons show that GapB differs from GapA in about 20% of its amino acid residues and by the presence of a flexible and negatively charged C-terminal extension, possibly responsible for the observed association of the enzyme with chloroplast envelopes in vitro. This C-terminal extension (29 or 30 residues) may be susceptible to proteolytic cleavage thereby leading to a conversion of chloroplast GAPDH isoenzyme I into isoenzyme II. Evolutionary rate comparisons at the amino acid sequence level show that chloroplast GapA and GapB evolve roughly two-fold slower than their cytosolic counterpart GapC. GapA and GapB transit peptides evolve about 10 times faster than the corresponding mature subunits. They are relatively long (68 and 83 residues for pea GapA and spinach GapB respectively) and share a similar amino acid framework with other chloroplast transit peptides
Dusty Planetary Systems
Extensive photometric stellar surveys show that many main sequence stars show
emission at infrared and longer wavelengths that is in excess of the stellar
photosphere; this emission is thought to arise from circumstellar dust. The
presence of dust disks is confirmed by spatially resolved imaging at infrared
to millimeter wavelengths (tracing the dust thermal emission), and at optical
to near infrared wavelengths (tracing the dust scattered light). Because the
expected lifetime of these dust particles is much shorter than the age of the
stars (>10 Myr), it is inferred that this solid material not primordial, i.e.
the remaining from the placental cloud of gas and dust where the star was born,
but instead is replenished by dust-producing planetesimals. These planetesimals
are analogous to the asteroids, comets and Kuiper Belt objects (KBOs) in our
Solar system that produce the interplanetary dust that gives rise to the
zodiacal light (tracing the inner component of the Solar system debris disk).
The presence of these "debris disks" around stars with a wide range of masses,
luminosities, and metallicities, with and without binary companions, is
evidence that planetesimal formation is a robust process that can take place
under a wide range of conditions. This chapter is divided in two parts. Part I
discusses how the study of the Solar system debris disk and the study of debris
disks around other stars can help us learn about the formation, evolution and
diversity of planetary systems by shedding light on the frequency and timing of
planetesimal formation, the location and physical properties of the
planetesimals, the presence of long-period planets, and the dynamical and
collisional evolution of the system. Part II reviews the physical processes
that affect dust particles in the gas-free environment of a debris disk and
their effect on the dust particle size and spatial distribution.Comment: 68 pages, 25 figures. To be published in "Solar and Planetary
Systems" (P. Kalas and L. French, Eds.), Volume 3 of the series "Planets,
Stars and Stellar Systems" (T.D. Oswalt, Editor-in-chief), Springer 201
Information-gathering for self-medication via Eastern Indonesian community pharmacies: a cross-sectional study
BACKGROUND: Gathering sufficient information when handling self-medication requests in community pharmacies is an important factor in assisting patients to obtain appropriate health outcomes. Common types of information usually gathered include patient identity, signs and symptoms, action taken, medical history, and current medications being used. The aims of the study were (1) to describe the types and amount of information gathered by Eastern Indonesian community pharmacy staff when handling self-medication requests, and (2) to identify factors associated with the reported amount of information gathered. METHODS: Patient simulation and pharmacy staff interviews were used. First, patient simulation was conducted using 2 cough scenarios and 1 diarrhoea scenario. Second, a structured interview was administered to eligible pharmacy staff in the setting. The types and amount of information gathered during patient simulation encounters and reported during pharmacy staff interviews were noted. A regression analysis was performed to identify factors associated with the amount of information gathered from the interview data. RESULTS: The most frequent types of information gathered in patient simulation encounters were the nature of symptoms (88% in one of the cough scenarios) and patient identity (96% in the diarrhoea scenario). Other types of information were gathered in <40% of encounters in each scenario. From the pharmacy staff interviews, >90% of the 173 interviewees reported that they gathered information on patient identity, nature of symptoms, and associated symptoms. Information on medical history and medication used was gathered by 20% and 26% respectively of the 173 interviewees. The majority of pharmacy staff asked 0 to 2 questions in the patient simulation encounters compared to 5 questions pharmacy staff reported as their usual practice during the interviews. Being qualified as a pharmacist or a pharmacy technician was one of the factors positively associated with the reported amount of information gathered. CONCLUSION: There were deficits in the types of information gathered when pharmacy staff handling self-medication requests. Having a pharmacy educational background and additional work experience in the pharmacy was positively associated with the reported amount of information gathered. There could be other factors contributing to shortcomings in the actual practice which need to be explored
The effect of Auger heating on intraband carrier relaxation in semiconductor quantumrods
The rate at which excited charge carriers relax to their equilibrium state
affects many aspects of the performance of nanoscale devices, including
switching speed, carrier mobility and luminescent efficiency. Better
understanding of the processes that govern carrier relaxation therefore has
important technological implications. A significant increase in carrier-carrier
interactions caused by strong spatial confinement of electronic excitations in
semiconductor nanostructures leads to a considerable enhancement of Auger
effects, which can further result in unusual, Auger-process-controlled
recombination and energy-relaxation regimes. Here, we report the first
experimental observation of efficient Auger heating in CdSe quantum rods at
high pump intensities, leading to a strong reduction of carrier cooling rates.
In this regime, the carrier temperature is determined by the balance between
energy outflow through phonon emission and energy inflow because of Auger
heating. This equilibrium results in peculiar carrier cooling dynamics that
closely correlate with recombination dynamics, an effect never before seen in
bulk or nanoscale semiconductors.Comment: 7 pages, 4 figure
Branch Mode Selection during Early Lung Development
Many organs of higher organisms, such as the vascular system, lung, kidney,
pancreas, liver and glands, are heavily branched structures. The branching
process during lung development has been studied in great detail and is
remarkably stereotyped. The branched tree is generated by the sequential,
non-random use of three geometrically simple modes of branching (domain
branching, planar and orthogonal bifurcation). While many regulatory components
and local interactions have been defined an integrated understanding of the
regulatory network that controls the branching process is lacking. We have
developed a deterministic, spatio-temporal differential-equation based model of
the core signaling network that governs lung branching morphogenesis. The model
focuses on the two key signaling factors that have been identified in
experiments, fibroblast growth factor (FGF10) and sonic hedgehog (SHH) as well
as the SHH receptor patched (Ptc). We show that the reported biochemical
interactions give rise to a Schnakenberg-type Turing patterning mechanisms that
allows us to reproduce experimental observations in wildtype and mutant mice.
The kinetic parameters as well as the domain shape are based on experimental
data where available. The developed model is robust to small absolute and large
relative changes in the parameter values. At the same time there is a strong
regulatory potential in that the switching between branching modes can be
achieved by targeted changes in the parameter values. We note that the sequence
of different branching events may also be the result of different growth
speeds: fast growth triggers lateral branching while slow growth favours
bifurcations in our model. We conclude that the FGF10-SHH-Ptc1 module is
sufficient to generate pattern that correspond to the observed branching modesComment: Initially published at PLoS Comput Bio
Relative efficacy of topical non-steroidal anti-inflammatory drugs and topical capsaicin in osteoarthritis: protocol for an individual patient data meta-analysis
Background
Pain is the most troubling issue to patients with osteoarthritis (OA), yet current pharmacological treatments offer only small-to-moderate pain reduction. Current guidelines therefore emphasise the need to identify predictors of treatment response. In line with these recommendations, an individual patient data (IPD) meta-analysis will be conducted. The study aims to investigate the relative treatment effects of topical non-steroidal anti-inflammatory drugs (NSAIDs) and topical capsaicin in OA and to identify patient-level predictors of treatment response.
Methods
IPD will be collected from randomised controlled trials (RCTs) of topical NSAIDs and capsaicin in OA. Multilevel regression modelling will be conducted to determine predictors for the specific and the overall treatment effect.
Discussion
Through the identification of treatment responders, this IPD meta-analysis may improve the current understanding of the pain mechanisms in OA and guide clinical decision-making. Identifying and prescribing the treatment most likely to be beneficial for an individual with OA will improve the efficiency of patient management
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