1,018 research outputs found

    High resolution infrared spectroscopy of the old open cluster NGC6791

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    We report abundance analysis for 6 M giant members of the old open cluster NGC6791, based on infrared spectroscopy (1.5-1.8 micron) at R=25,000, using the NIRSPEC spectrograph at the Keck II telescope. We find the iron abundance = +0.35 +/- 0.02$, confirming the super solar metallicity of this cluster derived from optical medium-high resolution spectroscopy. We also measure C, O and other alpha element abundances, finding roughly solar [alpha/Fe] and = -0.35. Our approach constrains [O/Fe] especially well, based on the measurement of a number of OH lines near 1.6micron; we find [O/Fe]=-0.07 +/-0.03. The Solar alpha enhancement is in contrast to the composition of similar stars in the Galactic bulge. We also find low 12C/13C~10, confirming the presence of extra-mixing processes during the red giant phase of evolution, up to super solar metallicities.Comment: 14 pages, 3 figures, accepted for publication on Ap

    A chemotaxonomic investigation on Vitis vinifera L. 3. Characterization of Vitis biotypes via root apex proteins

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    Soluble proteins from root tips were used as biochemical markers to study, taxonomically and systematically, Vitis biotypes. Analyses of total proteins in the pH range 3.5-10 and of the enzymes AcP, ADH, EST, PGM and POD indicate that only in the case of proteins and AcP the staining intensity of all samples and the variation of band pattern is taxonomically informative. A comparison between seed storage proteins and root tip proteins and an automatic data acquisition system is included

    The WFC3 Galactic Bulge Treasury Program: Metallicity Estimates for the Stellar Population and Exoplanet Hosts

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    We present new UV-to-IR stellar photometry of four low-extinction windows in the Galactic bulge, obtained with the Wide Field Camera 3 on the Hubble Space Telescope (HST). Using our five bandpasses, we have defined reddening-free photometric indices sensitive to stellar effective temperature and metallicity. We find that the bulge populations resemble those formed via classical dissipative collapse: each field is dominated by an old (~10 Gyr) population exhibiting a wide metallicity range (-1.5 < [Fe/H] < 0.5). We detect a metallicity gradient in the bulge population, with the fraction of stars at super-solar metallicities dropping from 41% to 35% over distances from the Galactic center ranging from 0.3 to 1.2 kpc. One field includes candidate exoplanet hosts discovered in the SWEEPS HST transit survey. Our measurements for 11 of these hosts demonstrate that exoplanets in the distinct bulge environment are preferentially found around high-metallicity stars, as in the solar neighborhood, supporting the view that planets form more readily in metal-rich environments.Comment: Accepted for publication in The Astrophysical Journal Letters. Latex, 5 pages, ApJ forma

    Extinction ratios in the inner Galaxy as revealed by the VVV survey

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    Accepted for publication in ApJ Letters, 10 pages, 3 Figures, 2 Tables © 2017 The American Astronomical Society. All rights reserved.Interstellar extinction towards the Galactic Center is large and significantly differential. Its reddening and dimming effects in red clump stars in the Galactic Bulge can be exploited to better constrain the extinction law towards the innermost Galaxy. By virtue of a deep and complete catalog of more than 30 million objets at l2.7deg|l|\le2.7\deg and b1.55deg|b|\le1.55\deg obtained from VVV survey observations, we apply the red clump method to infer the selective-to-total extinction ratios in the ZZ, YY, JJ, HH and KsK_s broadband near-infrared filters. The measured values are smaller than previously reported, and are not constant, with mean values, e.g., AKS/E(JKs)=0.428±0.005±0.04A_{K_S}/E(J-K_s)=0.428\pm0.005\pm0.04 and AKS/E(HKs)=1.104±0.022±0.2A_{K_S}/E(H-K_s)=1.104\pm0.022\pm0.2. We also obtain a ratio AZA_Z:AYA_Y:AJA_J:AHA_H:AKSA_{K_S} of 7.74:5.38:3.30:1.88:1.0, implying extinction towards the Galactic Center to follow a distribution as a function of wavelength steeper than previously reported, consistent with a power law Aλλ2.47A_{\lambda}\propto{\lambda}^{-2.47} in the near-infrared.Peer reviewedFinal Accepted Versio

    A new near-IR window of low extinction in the Galactic plane

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    Reproduced with permission from Astronomy & Astrophysics. © 2018 ESO. Comments: 6 pages, 6 figures. Accepted for publication in Astronomy & AstrophysicsAims. The windows of low extinction in the Milky Way (MW) plane are rare but important because they enable us to place structural constraints on the opposite side of the Galaxy, which has hither to been done rarely. Methods. We use the near-infrared (near-IR) images of the VISTA Variables in the Vía Láctea (VVV) Survey to build extinction maps and to identify low extinction windows towards the Southern Galactic plane. Here we report the discovery of VVV WIN 1713-3939, a very interesting window with relatively uniform and low extinction conveniently placed very close to the Galactic plane. Results. The new window of roughly 30 arcmin diameter is located at Galactic coordinates (l, b) = (347.4, -0.4) deg. We analyse the VVV near-IR colour-magnitude diagrams in this window. The mean total near-IR extinction and reddening values measured for this window are A Ks = 0.46 and E(J - K s) = 0.95. The red clump giants within the window show a bimodal magnitude distribution in the K s band, with peaks at K s = 14.1 and 14.8 mag, corresponding to mean distances of D = 11.0 ± 2.4 and 14.8 ± 3.6 kpc, respectively. We discuss the origin of these red clump overdensities within the context of the MW disk structure.Peer reviewe

    The Collection of Adipose Derived Stem Cells using Water-Jet Assisted Lipoplasty for their Use in Plastic and Reconstructive Surgery: A Preliminary Study

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    The graft of autologous fat for the augmentation of soft tissue is a common practice frequently used in the field of plastic and reconstructive surgery. In addition, the presence of adipose derived stem cells (ASCs) in adipose tissue stimulates the regeneration of tissue in which it is applied after the autologous fat grafting improving the final clinical results. Due to these characteristics, there is an increasing interest in the use of ASCs for the treatment of several clinical conditions. As a consequence, the use of clean room environment is required for the production of cell-based therapies. The present study is aimed to describe the biological properties of adipose tissue and cells derived from it cultured in vitro in clean room environment according to current regulation. The collection of adipose tissue was performed using the water-jet assisted liposuction in order to preserve an high cell viability increasing their chances of future use for different clinical application in the field of plastic and reconstructive surgery

    Vitamin D: Daily vs. Monthly Use in Children and Elderly-What Is Going On?

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    Vitamin D deficiency is highly prevalent among children and adults worldwide. Agreement exists that vitamin D deficiency should be corrected. However, the definitions of vitamin deficiency and effective vitamin D replacement therapy are inconsistent in the literature. Not only is the dosing regimen still under debate, but also the time and period of administration (i.e., daily vs. monthly dose). In pediatric as well as elderly subjects, dosing regimens with high vitamin D doses at less frequent intervals were proposed to help increase compliance to treatment: these became widespread in clinical practice, despite mounting evidence that such therapies are not only ineffective but potentially harmful, particularly in elderly subjects. Moreover, in the elderly, high doses of vitamin D seem to increase the risk of functional decline and are associated with a higher risk of falls and fractures. Achieving good adherence to recommended prophylactic regimens is definitely one of the obstacles currently being faced in view of the wide segment of the population liable to the treatment and the very long duration of prophylaxis. The daily intake for extended periods is in fact one of the frequent causes of therapeutic drop-outs, while monthly doses of vitamin D may effectively and safely improve patient compliance to the therapy. The aim of our paper is a quasi-literature review on dosing regimens among children and elderly. These two populations showed a particularly significant beneficial effect on bone metabolism, and there could be different outcomes with different dosing regimens

    AN EMPIRICAL TOOL TO DERIVE METALLICITY, REDDENING, AND DISTANCE FOR OLD STELLAR POPULATIONS FROM NEAR-INFRARED COLOR-MAGNITUDE DIAGRAMS 1

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    ABSTRACT We present an empirical method to derive photometric metallicity, reddening, and distance to old stellar populations by using a few major features of the red giant branch (RGB) in near-IR color-magnitude diagrams. We combine the observed RGB features with a set of equations linking the global metallicity [M/H] to suitable RGB parameters (colors, magnitudes, and slope), as calibrated from a homogeneous sample of Galactic globular clusters with different metallicities. This technique can be applied to efficiently derive the main population parameters of old stellar systems, with the goal of using ground-based adaptive optics and space facilities to probe the stellar content of remote galaxies
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