7,317 research outputs found
Investigation of the parameters of a dense, inductively generated stripping plasma for the FAIR-Project
New model of calculating the energy transfer efficiency for the spherical theta-pinch device
Ion-beam-plasma-interaction plays an important role in the field of Warm
Dense Matter (WDM) and Inertial Confinement Fusion (ICF). A spherical theta
pinch is proposed to act as a plasma target in various applications including a
plasma stripper cell. One key parameter for such applications is the free
electron density. A linear dependency of this density to the amount of energy
transferred into the plasma from an energy storage was found by C. Teske. Since
the amount of stored energy is known, the energy transfer efficiency is a
reliable parameter for the design of a spherical theta pinch device. The
traditional two models of energy transfer efficiency are based on assumptions
which comprise the risk of systematical errors. To obtain precise results, this
paper proposes a new model without the necessity of any assumption to calculate
the energy transfer efficiency for an inductively coupled plasma device.
Further, a comparison of these three different models is given at a fixed
operation voltage for the full range of working gas pressures. Due to the
inappropriate assumptions included in the traditional models, one owns a
tendency to overestimate the energy transfer efficiency whereas the other leads
to an underestimation. Applying our new model to a wide spread set of operation
voltages and gas pressures, an overall picture of the energy transfer
efficiency results
The Timing of Nine Globular Cluster Pulsars
We have used the Robert C. Byrd Green Bank Telescope to time nine previously
known pulsars without published timing solutions in the globular clusters M62,
NGC 6544, and NGC 6624. We have full timing solutions that measure the spin,
astrometric, and (where applicable) binary parameters for six of these pulsars.
The remaining three pulsars (reported here for the first time) were not
detected enough to establish solutions. We also report our timing solutions for
five pulsars with previously published solutions, and find good agreement with
past authors, except for PSR J1701-3006B in M62. Gas in this system is probably
responsible for the discrepancy in orbital parameters, and we have been able to
measure a change in the orbital period over the course of our observations.
Among the pulsars with new solutions we find several binary pulsars with very
low mass companions (members of the so-called "black widow" class) and we are
able to place constraints on the mass-to-light ratio in two clusters. We
confirm that one of the pulsars in NGC 6624 is indeed a member of the rare
class of non-recycled pulsars found in globular clusters. We also have measured
the orbital precession and Shapiro delay for a relativistic binary in NGC 6544.
If we assume that the orbital precession can be described entirely by general
relativity, which is likely, we are able to measure the total system mass
(2.57190(73) M_sun) and companion mass (1.2064(20) M_sun), from which we derive
the orbital inclination [sin(i) = 0.9956(14)] and the pulsar mass (1.3655(21)
M_sun), the most precise such measurement ever obtained for a millisecond
pulsar. The companion is the most massive known around a fully recycled pulsar.Comment: Published in ApJ; 33 pages, 5 figures, 7 table
Testing the binary hypothesis for the formation and shaping of planetary nebulae
There is no quantitative theory to explain why a high 80% of all planetary
nebulae are non-spherical. The Binary Hypothesis states that a companion to the
progenitor of a central star of planetary nebula is required to shape the
nebula and even for a planetary nebula to be formed at all. A way to test this
hypothesis is to estimate the binary fraction of central stars of planetary
nebulae and to compare it with that of the main sequence population.
Preliminary results from photometric variability and the infrared excess
techniques indicate that the binary fraction of central stars of planetary
nebulae is higher than that of the main sequence, implying that PNe could
preferentially form via a binary channel. This article briefly reviews these
results and current studies aiming to refine the binary fraction.Comment: EUROWD12 Proceeding
Planetary nebulae : getting closer to an unbiased binary fraction
Why 80% of planetary nebulae are not spherical is not yet understood. The
Binary Hypothesis states that a companion to the progenitor of the central star
of a planetary nebula is required to shape the nebula and even for a planetary
nebula to be formed at all. A way to test this hypothesis is to estimate the
binary fraction of central stars of planetary nebula and to compare it with the
main sequence population. Preliminary results from photometric variability and
infrared excess techniques indicate that the binary fraction of central stars
of planetary nebulae is higher than that of the putative main sequence
progenitor population, implying that PNe could be preferentially formed via a
binary channel. This article briefly reviews these results and future studies
aiming to refine the binary fraction.Comment: SF2A 2012 proceeding
Early infant feeding and adiposity risk: from infancy to adulthood
Introduction: Systematic reviews suggest that a longer duration of breast-feeding is associated with a reduction in the risk of later overweight and obesity. Most studies examining breast-feeding in relation to adiposity have not used longitudinal analysis. In our study, we aimed to examine early infant feeding and adiposity risk in a longitudinal cohort from birth to young adulthood using new as well as published data.
Methods: Data from the Western Australian Pregnancy Cohort (Raine) Study in Perth, W.A., Australia, were used to examine associations between breast-feeding and measures of adiposity at 1, 2, 3, 6, 8, 10, 14, 17, and 20 years.
Results: Breast-feeding was measured in a number of ways. Longer breast-feeding (in months) was associated with reductions in weight z-scores between birth and 1 year (β = -0.027; p \u3c 0.001) in the adjusted analysis. At 3 years, breast-feeding for \u3c4 months increased the odds of infants experiencing early rapid growth (OR 2.05; 95% CI 1.43-2.94; p \u3c 0.001). From 1 to 8 years, children breast-fed for ≤4 months compared to ≥12 months had a significantly greater probability of exceeding the 95th percentile of weight. The age at which breast-feeding was stopped and a milk other than breast milk was introduced (introduction of formula milk) played a significant role in the trajectory of the BMI from birth to 14 years; the 4-month cutoff point was consistently associated with a higher BMI trajectory. Introduction of a milk other than breast milk before 6 months compared to at 6 months or later was a risk factor for being overweight or obese at 20 years of age (OR 1.47; 95% CI 1.12-1.93; p = 0.005).
Discussion: Breast-feeding until 6 months of age and beyond should be encouraged and is recommended for protection against increased adiposity in childhood, adolescence, and young adulthood. Adverse long-term effects of early growth acceleration are fundamental in later overweight and obesity. Formula feeding stimulates a higher postnatal growth velocity, whereas breast-feeding promotes slower growth and a reduced likelihood of overweight and obesity. Biological mechanisms underlying the protective effect of breast-feeding against obesity are based on the unique composition and metabolic and physiological responses to human milk
Ariel - Volume 2 Number 7
Editors
Richard J. Bonanno
Robin A. Edwards
Associate Editors
Steven Ager
Stephen Flynn
Shep Dickman
Tom Williams
Lay-out Editor
Eugenia Miller
Contributing Editors
Michael J. Blecker
W. Cherry Light
James J. Nocon
Lynne Porter
Editors Emeritus
Delvyn C. Case, Jr.
Paul M. Fernhof
"Gastroesophageal reflux disease"
Geoffrey C. Wall is an Associate Professor of Pharmacy Practice in the College of Pharmacy and Health Sciences. He can be contacted at [email protected]: Gastroesophageal reflux disease (GERD) is a pathologic condition of injury to the esophagus caused by regurgitation of gastric or gastroduodenal contents into the lumen of the
esophagus. Histopathology of the esophageal mucosa may or may not be present. Gastroesophageal reflux of acid and gastric contents often causes a condition commonly referred to as heartburn. This is characterized as a retro-sternal burning
sensation that radiates to the throat and interscapular region. It may be confused, even in the emergency room, with anginal pain or the onset of myocardial infarction; therefore its rapid
diagnosis is important. In many patients GERD should be considered a chronic and lifelong illness and maintenance therapy is often needed. Repeated exposure of the esophagus to stomach contents leads to esophagitis. In severe cases, this can actually erode esophageal tissue (erosive esophagitis). In the last five to seven years several new treatment options for GERD have become available. These include antise-cretory agents such as the proton pump inhibitors, and new surgical techniques that have improved Nissen fundoplication safety and efficacy rates(3-4). Clinicians caring for patients with this
common disorder need to understand the pathology behind GERD, its common (and uncommon) clinical manifestations, and current treatment options as recommended by the American College of Gastroenterology
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