8,259 research outputs found
Abundance analysis for long-period variables II. RGB and AGB stars in the globular cluster 47\,Tuc
Asymptotic giant branch (AGB) stars play a key role in the enrichment of
galaxies with heavy elements. Due to their large amplitude variability, the
measurement of elemental abundances is a highly challenging task that has not
been solved in a satisfactory way yet.
Following our previous work we use hydrostatic and dynamical model
atmospheres to simulate observed high-resolution near-infrared spectra of 12
variable and non-variable red giants in the globular cluster 47 Tuc. The 47 Tuc
red giants are independently well-characterized in important parameters (mass,
metallicity, luminosity). The principal aim was to compare synthetic spectra
based on the dynamical models with observational spectra of 47 Tuc variables.
Assuming that the abundances are unchanged on the upper giant branch in these
low-mass stars, our goal is to estimate the impact of atmospheric dynamics on
the abundance determination.
We present new measurements of the C/O and 12C/13C ratio for 5 non-variable
red giants in 47Tuc. The equivalent widths measured for our 7 variable stars
strongly differ from the non-variable stars and cannot be reproduced by either
hydrostatic or dynamical model atmospheres. Nevertheless, the dynamical models
fit the observed spectra of long-period variables much better than any
hydrostatic model. For some spectral features, the variations in the line
intensities predicted by dynamical models over a pulsation cycle give similar
values as a sequence of hydrostatic models with varying temperature and
constant surface gravity.Comment: 16 pages, 12 figures; accepted for publication in A&
Nuclei embedded in an electron gas
The properties of nuclei embedded in an electron gas are studied within the
relativistic mean-field approach. These studies are relevant for nuclear
properties in astrophysical environments such as neutron-star crusts and
supernova explosions. The electron gas is treated as a constant background in
the Wigner-Seitz cell approximation. We investigate the stability of nuclei
with respect to alpha and beta decay. Furthermore, the influence of the
electronic background on spontaneous fission of heavy and superheavy nuclei is
analyzed. We find that the presence of the electrons leads to stabilizing
effects for both decay and spontaneous fission for high electron
densities. Furthermore, the screening effect shifts the proton dripline to more
proton-rich nuclei, and the stability line with respect to beta decay is
shifted to more neutron-rich nuclei. Implications for the creation and survival
of very heavy nuclear systems are discussed.Comment: 35 pages, latex+ep
Recent innovations in UHPLC columns and instrumentation
AbstractTen years after the introduction of the first commercial ultra-high-performance liquid chromatography (UHPLC) system, the pace of progress has not slowed. We describe recent innovations in UHPLC columns and instruments, focusing on those intended primarily for reversed-phase separations of analytes with molecular weights less than about 5000 Daltons, using columns with internal diameters of 2.1 mm. New columns packed with sub-2-µm solid-core particles have produced efficiencies greater than 400,000 plates/m, more than 40% higher than those of columns packed with sub-2-µm fully porous particles. In addition, columns containing charged surface particles give higher peak capacities for separations of positively charged analytes when using the low ionic strength, acidic mobile phases preferred for electrospray mass spectrometric detection. The narrow peaks produced by these columns require instruments having extremely low dispersion. We review recent progress in measuring and reducing system dispersion
THE ECONOMICS OF CARCASS BEEF PRODUCTION: AN APPRAISAL OF FLORIDA'S FEEDLOT POTENTIAL
Livestock Production/Industries,
The radial variation of HI velocity dispersions in dwarfs and spirals
Gas velocity dispersions provide important diagnostics of the forces
counteracting gravity to prevent collapse of the gas. We use the 21 cm line of
neutral atomic hydrogen (HI) to study HI velocity dispersion and HI phases as a
function of galaxy morphology in 22 galaxies from The HI Nearby Galaxy Survey
(THINGS). We stack individual HI velocity profiles and decompose them into
broad and narrow Gaussian components. We study the HI velocity dispersion and
the HI surface density, as a function of radius. For spirals, the velocity
dispersions of the narrow and broad components decline with radius and their
radial profiles are well described by an exponential function. For dwarfs,
however, the profiles are much flatter. The single Gaussian dispersion profiles
are, in general, flatter than those of the narrow and broad components. In most
cases, the dispersion profiles in the outer disks do not drop as fast as the
star formation profiles, derived in the literature. This indicates the
importance of other energy sources in driving HI velocity dispersion in the
outer disks. The radial surface density profiles of spirals and dwarfs are
similar. The surface density profiles of the narrow component decline more
steeply than those of the broad component, but not as steep as what was found
previously for the molecular component. As a consequence, the surface density
ratio between the narrow and broad components, an estimate of the mass ratio
between cold HI and warm HI, tends to decrease with radius. On average, this
ratio is lower in dwarfs than in spirals. This lack of a narrow, cold HI
component in dwarfs may explain their low star formation activity.Comment: Accepted for publication in The Astronomical Journal, 13 pages, 10
figures, 4 table
Involvement of UDP-Glucuronosyltransferases and Sulfotransferases in the Excretion and Tissue Distribution of Resveratrol in Mice.
Resveratrol is a naturally occurring polyphenolic compound with various pharmacological activities. It is unknown whether the expression of metabolizing enzymes correlates with resveratrol levels in organs and tissues. Therefore, we investigated the metabolism and tissue distribution of resveratrol in mice and assessed its association with the expression of UDP-glucuronosyltransferase (Ugt) and sulfotransferase (Sult) genes. Plasma, urine, feces, and various organs were analyzed using high-performance liquid chromatography at up to 8 h after intragastric resveratrol administration. The metabolism of resveratrol was pronounced, leading to the formation of resveratrol glucuronides and sulfates. Concentrations of resveratrol and its metabolites were high in the gastrointestinal organs, urine, and feces, but low in the liver and kidneys. In lung, heart, thymus, and brain tissues, parent resveratrol levels exceeded the sulfate and glucuronide concentrations. The formation of resveratrol conjugates correlated with the expression of certain Ugt and Sult genes. Reverse transcription quantitative PCR (RT-qPCR) analysis revealed high mRNA expression of Ugt1a1 and Ugt1a6a in the liver, duodenum, jejunum, ileum, and colon, leading to high concentrations of resveratrol-3-O-glucuronide in these organs. Strong correlations of resveratrol-3-O-sulfate and resveratrol-3-O-4'-O-disulfate formation with Sult1a1 mRNA expression were also observed, particularly in the liver and colon. In summary, our data revealed organ-specific expression of Sults and Ugts in mice that strongly affects resveratrol concentrations; this may also be predictive in humans following oral uptake of dietary resveratrol
Economic appraisal of service forester activities in Mississippi
The importance of nonindustrial private forest( NIPF) lands to national timber output potential is well-documented (USDA Forest Service 1981, 1982; Wall 1981). The NIPF sector controls 58 percent of the Nation\u27s commercial fm·est area, compared to 14- percent in forest industry holdings, and 28 percent in public forests (Figure 1). Approximately 71 percent of the commercial forest area in the eastern United States is held by the NIPF sector
Smart Cardiovascular Stent against In-Stent Restenosis
Jump Starting Technologies, Patent Issues, & Translational Medicine Poster SessionA smart cardiovascular stent to be used as a single set of theranostics (therapeutics and diagnostics) is developed. The stent is aimed at delivering nitric oxide as a therapeutic agent and monitoring stent-induced restenosis. This novel approach is intended to reduce the risks stemmed from implanted stents and lowering manufacturing cost. The proposed stent will provide a non-invasive and continuous monitoring of restenosis caused by the stent. To assess the level of restenosis, pressure and blood flow will be monitored inside the blood vessel where the stent is placed. Existing techniques that employ catheters to measure pressure inside blood vessels are not suitable because they are too invasive, cannot monitor pressure for long periods of time and restrict the patient to be in a hospital setting. Our approach consists of two miniature pressure sensors and a small microchip incorporated into the stent. The pressure sensors are placed at the opposite sides of the stent. Blood flow is obtained by assessing the pressure difference at these two points. The microchip reads out the pressure sensors outputs and wirelessly transmits them to a reader outside the body. Due to size constraints and safety reasons a battery cannot be used as a power source for the microchip. Instead, power is provided from the reader via electromagnetic coupling. In order to reduce the number of components to be implanted, we are proposing to employ the stent body not only as a mechanical supporter but also as an antenna. To provide an optimal power match between the microchip and the antenna, the impedance of the stent was fully characterized. This characterization has been performed using computer simulations of five different commercially available stent designs. It was found that at the frequencies of interest (902 to 928 MHz) the impedance is highly reactive. To compensate for the reactive impedance of the antenna, a matching network was designed. A prototype microchip with different components has been designed and is currently being fabricated. Future work includes micro-assembly of a prototype stent for the collection of pressure measurements using an aortic bifurcation model. Once completed, this stent will be useful in monitoring the level of restenosis and will lower the risks presented by implantable stents
Integration of HIV Care with Primary Health Care Services: Effect on Patient Satisfaction and Stigma in Rural Kenya.
HIV departments within Kenyan health facilities are usually better staffed and equipped than departments offering non-HIV services. Integration of HIV services into primary care may address this issue of skewed resource allocation. Between 2008 and 2010, we piloted a system of integrating HIV services into primary care in rural Kenya. Before integration, we conducted a survey among returning adults ≥18-year old attending the HIV clinic. We then integrated HIV and primary care services. Three and twelve months after integration, we administered the same questionnaires to a sample of returning adults attending the integrated clinic. Changes in patient responses were assessed using truncated linear regression and logistic regression. At 12 months after integration, respondents were more likely to be satisfied with reception services (adjusted odds ratio, aOR 2.71, 95% CI 1.32-5.56), HIV education (aOR 3.28, 95% CI 1.92-6.83), and wait time (aOR 1.97 95% CI 1.03-3.76). Men's comfort with receiving care at an integrated clinic did not change (aOR = 0.46 95% CI 0.06-3.86). Women were more likely to express discomfort after integration (aOR 3.37 95% CI 1.33-8.52). Integration of HIV services into primary care services was associated with significant increases in patient satisfaction in certain domains, with no negative effect on satisfaction
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