1,057 research outputs found

    Detailed Analysis of Nearby Bulgelike Dwarf Stars III. Alpha and Heavy-element abundances

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    The present sample of nearby bulgelike dwarf stars has kinematics and metallicities characteristic of a probable inner disk or bulge origin. Ages derived by using isochrones give 10-11 Gyr for these stars and metallicities are in the range -0.80< [Fe/H]< +0.40. We calculate stellar parameters from spectroscopic data, and chemical abundances of Mg, Si, Ca, Ti, La, Ba, Y, Zr and Eu are derived by using spectrum synthesis. We found that [alpha-elements/Fe] show different patterns depending on the element. Si, Ca and Ti-to-iron ratios decline smoothly for increasing metallicities, and follow essentially the disk pattern. O and Mg, products of massive supernovae, and also the r-process element Eu, are overabundant relative to disk stars, showing a steeper decline for metallicities [Fe/H] > -0.3 dex. [s-elements/Fe] roughly track the solar values with no apparent trend with metallicity for [Fe/H] < 0, showing subsolar values for the metal rich stars. Both kinematical and chemical properties of the bulgelike stars indicate a distinct identity of this population when compared to disk stars.Comment: 21 pages, 9 figures, to appear in Ap

    Downregulation of HLA Class I Renders Inflammatory Neutrophils More Susceptible to NK Cell-Induced Apoptosis

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    Neutrophils are potent effector cells and contain a battery of harmful substances and degrading enzymes. A silent neutrophil death, i.e., apoptosis, is therefore of importance to avoid damage to the surrounding tissue and to enable termination of the acute inflammatory process. There is a pile of evidence supporting the role for pro-inflammatory cytokines in extending the life-span of neutrophils, but relatively few studies have been devoted to mechanisms actively driving apoptosis induction in neutrophils. We have previously demonstrated that natural killer (NK) cells can promote apoptosis in healthy neutrophils. In this study, we set out to investigate how neutrophil sensitivity to NK cell-mediated cytotoxicity is regulated under inflammatory conditions. Using in vitro-activated neutrophils and a human skin chamber model that allowed collection of in vivo-transmigrated neutrophils, we performed a comprehensive characterization of neutrophil expression of ligands to NK cell receptors. These studies revealed a dramatic downregulation of HLA class I molecules in inflammatory neutrophils, which was associated with an enhanced susceptibility to NK cell cytotoxicity. Collectively, our data shed light on the complex regulation of interactions between NK cells and neutrophils during an inflammatory response and provide further support for a role of NK cells in the resolution phase of inflammation

    Gel chromatographic characterization of immunoreactive adrenocorticotropin in patients with ACTH hypersecretion

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    We investigated the molecular size of circulating immunoreactive ACTH by gel chromatography in patients with ACTH hypersecretion due to various disorders of the hypothalamic-pituitary-adrenal axis. 4 patients with Addison's disease, 2 with Nelson's syndrome, 4 with Cushing's disease, 6 with the ectopic ACTH syndrome (2 bronchial carcinoma, 1 medullary carcinoma, 1 metastatic islett cell carcinoma, 1 benign bronchial carcinoid and 1 patient with occult ectopic Cushing's syndrome) and 1 patient with hypersecretion of ACTH from a clinically nonfunctioning pituitary adenoma were studied. Analysis of the molecular size of immunoreactive ACTH was performed by gel chromatography on a Sephadex G-75 column (superfine, 100×1.5 cm) equilibrated with 1% formic acid. 2 ml fractions were collected and evaporated to dryness. The ACTH content of the recovered samples was determined by RIA. In Addison's disease, Nelson's syndrome and Cushing's disease the plasma showed a single peak of ACTH immunoreactivity at the expected position of 1–39 ACTH. In the ectopic ACTH syndrome the plasma of 4 patients revealed at chromatography at least one other peak eluting between the void volume and 1–39 ACTH suggestive of a high molecular weight form of ACTH whereas plasma of 2 patients showed only a single ACTH peak at the position of labeled 1–39 ACTH. The patient with a clinically non-functioning pituitary adenoma revealed a gel filtration pattern similar to the patients with ectopic ACTH syndrom and secretion of high molecular weight ACTH. We conclude that secretion of high molecular weight forms of ACTH is not a unique feature of the ectopic ACTH syndrome. It may therefore not serve as a marker of the ectopic Cushing's syndrome in the differential diagnosis of the ACTH dependent Cushing's syndrome. Vice versa, lack of high molecular weight ACTH does not exclude an ectopic source of ACTH secretion as cause of Cushing's syndrome

    Elemental Abundance Ratios in Stars of the Outer Galactic Disk. II. Field Red Giants

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    We summarize a selection process to identify red giants in the direction of the southern warp of the Galactic disk, employing VI_C photometry and multi-object spectroscopy. We also present results from follow-up high-resolution, high-S/N echelle spectroscopy of three field red giants, finding [Fe/H] values of about -0.5. The field stars, with Galactocentric distances estimated at 10 to 15 kpc, support the conclusion of Yong, Carney, & de Almeida (2005) that the Galactic metallicity gradient disappears beyond R_GC values of 10 to 12 kpc for the older stars and clusters of the outer disk. The field and cluster stars at such large distances show very similar abundance patterns, and, in particular, all show enhancements of the "alpha" elements O, Mg, Si, Ca, and Ti and the r-process element Eu. These results suggest that Type II supernovae have been significant contributors to star formation in the outer disk relative to Type Ia supernovae within the past few Gyrs. We also compare our results with those available for much younger objects. The limited results for the H II regions and B stars in the outer disk also suggest that the radial metallicity gradient in the outer disk is shallow or absent. The much more extensive results for Cepheids confirm these trends, and that the change in slope of the metallicity gradient may occur at a larger Galactocentric distance than for the older stars and clusters. However, the younger stars also show rising alpha element enhancements with increasing R_GC, at least beyond 12 kpc. These trends are consistent with the idea of a progressive growth in the size of the Galactic disk with time, and episodic enrichment by Type II supernovae as part of the disk's growth. [Abridged]Comment: Accepted for publication in A

    Magnesium isotope ratios in Hyades stars

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    Using classical model atmospheres and an LTE analysis, Mg isotope ratios 24Mg:25Mg:26Mg are measured in 32 Hyades dwarfs covering 4000K < Teff < 5000K. We find no significant trend in any isotope ratio versus Teff and the mean isotope ratio is in excellent agreement with the solar value. We determine stellar parameters and Fe abundances for 56 Hyades dwarfs covering 4000K < Teff < 6200K. For stars warmer than 4700K, we derive a cluster mean value of [Fe/H] = 0.16 +/- 0.02 (sigma=0.1), in good agreement with previous studies. For stars cooler than 4700K, we find that the abundance of Fe from ionized lines exceeds the abundance of Fe from neutral lines. At 4700K [Fe/H]_II - [Fe/H]_I = 0.3 dex while at 4000K [Fe/H]_II - [Fe/H]_I = 1.2 dex. This discrepancy between the Fe abundance from neutral and ionized lines likely reflects inadequacies in the model atmospheres and the presence of Non-LTE or other effects. Despite the inability of the models to reproduce ionization equilibrium for Fe, the Mg isotope ratios appear immune to these problems and remain a powerful tool for studying Galactic chemical evolution.Comment: ApJ in press (March 10 2004

    Why nature matters: A systematic review of intrinsic, instrumental, and relational values

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    \ua9 2023 The Author(s). Published by Oxford University Press on behalf of the American Institute of Biological Sciences. In this article, we present results from a literature review of intrinsic, instrumental, and relational values of nature conducted for the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services, as part of the Methodological Assessment of the Diverse Values and Valuations of Nature. We identify the most frequently recurring meanings in the heterogeneous use of different value types and their association with worldviews and other key concepts. From frequent uses, we determine a core meaning for each value type, which is sufficiently inclusive to serve as an umbrella over different understandings in the literature and specific enough to help highlight its difference from the other types of values. Finally, we discuss convergences, overlapping areas, and fuzzy boundaries between different value types to facilitate dialogue, reduce misunderstandings, and improve the methods for valuation of nature\u27s contributions to people, including ecosystem services, to inform policy and direct future research

    Search for the decay J/ψ→γ+invisibleJ/\psi\to\gamma + \rm {invisible}

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    We search for J/ψJ/\psi radiative decays into a weakly interacting neutral particle, namely an invisible particle, using the J/ψJ/\psi produced through the process ψ(3686)→π+π−J/ψ\psi(3686)\to\pi^+\pi^-J/\psi in a data sample of (448.1±2.9)×106(448.1\pm2.9)\times 10^6 ψ(3686)\psi(3686) decays collected by the BESIII detector at BEPCII. No significant signal is observed. Using a modified frequentist method, upper limits on the branching fractions are set under different assumptions of invisible particle masses up to 1.2  GeV/c2\mathrm{\ Ge\kern -0.1em V}/c^2. The upper limit corresponding to an invisible particle with zero mass is 7.0×10−7\times 10^{-7} at the 90\% confidence level

    First observations of hc→h_c \to hadrons

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    Based on (4.48±0.03)×108(4.48 \pm 0.03) \times 10^{8} ψ(3686)\psi(3686) events collected with the BESIII detector, five hch_c hadronic decays are searched for via process ψ(3686)→π0hc\psi(3686) \to \pi^0 h_c. Three of them, hc→ppˉπ+π−h_c \to p \bar{p} \pi^+ \pi^-, π+π−π0\pi^+ \pi^- \pi^0, and 2(π+π−)π02(\pi^+ \pi^-) \pi^0 are observed for the first time, with statistical significances of 7.4σ\sigma, 4.9σ4.9\sigma, and 9.1σ\sigma, and branching fractions of (2.89±0.32±0.55)×10−3(2.89\pm0.32\pm0.55)\times10^{-3}, (1.60±0.40±0.32)×10−3(1.60\pm0.40\pm0.32)\times10^{-3}, and (7.44±0.94±1.56)×10−3(7.44\pm0.94\pm1.56)\times10^{-3}, respectively, where the first uncertainties are statistical and the second systematic. No significant signal is observed for the other two decay modes, and the corresponding upper limits of the branching fractions are determined to be B(hc→3(π+π−)π0)<8.7×10−3B(h_c \to 3(\pi^+ \pi^-) \pi^0)<8.7\times10^{-3} and B(hc→K+K−π+π−)<5.8×10−4B(h_c \to K^+ K^- \pi^+ \pi^-)<5.8\times10^{-4} at 90% confidence level.Comment: 17 pages, 16 figure
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