1,816 research outputs found

    The ortho-to-para ratio of ammonia in the L1157 outflow

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    We have measured the ortho-to-para ratio of ammonia in the blueshifted gas of the L1157 outflow by observing the six metastable inversion lines from (J, K) = (1, 1) to (6, 6). The highly excited (5, 5) and (6, 6) lines were first detected in the low-mass star forming regions. The rotational temperature derived from the ratio of four transition lines from (3, 3) to (6, 6) is 130-140 K, suggesting that the blueshifted gas is heated by a factor of ~10 as compared to the quiescent gas. The ortho-to-para ratio of the NH3 molecules in the blueshifted gas is estimated to be 1.3--1.7, which is higher than the statistical equilibrium value. This ratio provides us with evidence that the NH3 molecules have been evaporated from dust grains with the formation temperature between 18 and 25 K. It is most likely that the NH3 molecules on dust grains have been released into the gas phase through the passage of strong shock waves produced by the outflow. Such a scenario is supported by the fact that the ammonia abundance in the blueshifted gas is enhanced by a factor of ~5 with respect to the dense quiescent gas.Comment: 16 pages, including 3 PS figures. To appear in the ApJ (Letters). aastex macro

    A major star formation region in the receding tip of the stellar Galactic bar

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    We present an analysis of the optical spectroscopy of 58 stars in the Galactic plane at l=27l=27\arcdeg, where a prominent excess in the flux distribution and star counts have been observed in several spectral regions, in particular in the Two Micron Galactic Survey (TMGS) catalog. The sources were selected from the TMGS, to have a KK magnitude brighter than +5 mag and be within 2 degrees of the Galactic plane. More than 60% of the spectra correspond to stars of luminosity class I, and a significant proportion of the remainder are very late giants which would also be fast evolving. This very high concentration of young sources points to the existence of a major star formation region in the Galactic plane, located just inside the assumed origin of the Scutum spiral arm. Such regions can form due to the concentrations of shocked gas where a galactic bar meets a spiral arm, as is observed at the ends of the bars of face-on external galaxies. Thus, the presence of a massive star formation region is very strong supporting evidence for the presence of a bar in our Galaxy.Comment: 13 pages (latex) + 4 figures (eps), accepted in ApJ Let

    Fermi surface induced lattice distortion in NbTe2_2

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    The origin of the monoclinic distortion and domain formation in the quasi two-dimensional layer compound NbTe2_2 is investigated. Angle-resolved photoemission shows that the Fermi surface is pseudogapped over large portions of the Brillouin zone. Ab initio calculation of the electron and phonon bandstructure as well as the static RPA susceptibility lead us to conclude that Fermi surface nesting and electron-phonon coupling play a key role in the lowering of the crystal symmetry and in the formation of the charge density wave phase

    Synthetic Spectra and Color-Temperature Relations of M Giants

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    As part of a project to model the integrated spectra and colors of elliptical galaxies through evolutionary synthesis, we have refined our synthetic spectrum calculations of M giants. After critically assessing three effective temperature scales for M giants, we adopted the relation of Dyck et al. (1996) for our models. Using empirical spectra of field M giants as a guide, we then calculated MARCS stellar atmosphere models and SSG synthetic spectra of these cool stars, adjusting the band absorption oscillator strengths of the TiO bands to better reproduce the observational data. The resulting synthetic spectra are found to be in very good agreement with the K-band spectra of stars of the appropriate spectral type taken from Kleinmann & Hall (1986) as well. Spectral types estimated from the strengths of the TiO bands and the depth of the bandhead of CO near 2.3 microns quantitatively confirm that the synthetic spectra are good representations of those of field M giants. The broad-band colors of the models match the field relations of K and early-M giants very well; for late-M giants, differences between the field-star and synthetic colors are probably caused by the omission of spectral lines of VO and water in the spectrum synthesis calculations. Here, we present four grids of K-band bolometric corrections and colors -- Johnson U-V and B-V; Cousins V-R and V-I; Johnson-Glass V-K, J-K and H-K; and CIT/CTIO V-K, J-K, H-K and CO -- for models having 3000 K < Teff < 4000 K and -0.5 < log g < 1.5. These grids, which have [Fe/H] = +0.25, 0.0, -0.5 and -1.0, extend and supplement the color-temperature relations of hotter stars presented in a companion paper (astro-ph/9911367).Comment: To appear in the March 2000 issue of the Astronomical Journal. 60 pages including 15 embedded postscript figures (one page each) and 6 embedded postscript tables (10 pages total

    Clinical and microbiological assessment of patients with a long-term diagnosis of human immunodeficiency virus infection and Candida oral colonization

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    The objective of this study was to evaluate Candida oral colonization in human immunodeficiency virus (HIV)-infected patients undergoing long-term highly active antiretroviral therapy (ARV). the cross-sectional study included 331 HIV patients, diagnosed from 1983 to 2003. Oral swabs were performed, and Candida species were determined using ID 32C. Isolates were tested for antifungal susceptibility. Clinical and laboratory data were collected to identify the association with Candida colonization. in total, 161 Candida isolates were detected among 147 of the 331 patients (44%), independently of the time when HIV infection was diagnosed. Candida albicans strains represented 137 (85%) of the isolates, and were susceptible to all of the tested antifungal drugs. Among the non-C. albicans strains, six isolates were dose-dependently susceptible to fluconazole, nine to itraconazole, and seven to ketoconazole. the isolation of Candida was significantly higher in patients with virological failure (83/147; p 0.0002) and CD4(+) T-lymphocyte counts < 200 cells/mm(3) (30/83; p 0.0003). Recovery of Candida in the oral cavity was independent of protease inhibitor (PI) usage (p 0.60). Colonized patients typically underwent salvage therapy (p 0.003), and had more episodes of opportunistic fungal infections (p 0.046) and malignancies (p 0.004). Oral Candida colonization in patients under ARV therapy was associated with the immunosupressed status of HIV-infected patients, i.e. low number of CD4(+) T-cells per cubic millimetre, failure of ARV therapy (salvage therapy), and higher number of opportunistic infections and malignancies. Despite the fact that PIs have in vitro antifungal activity, the use of this class of antiretroviral agent did not influence the presence of Candida in the oral cavity of AIDS patients.Univ Estadual Campinas, Dept Internal Med, Fac Med Sci, Div Infect Dis, BR-13081070 Campinas, SP, BrazilUniversidade Federal de SĂŁo Paulo, Div Infect Dis, SĂŁo Paulo, BrazilChiba Univ, Med Mycol Res Ctr, Chiba, JapanUniversidade Federal de SĂŁo Paulo, Div Infect Dis, SĂŁo Paulo, BrazilWeb of Scienc

    Clinical and microbiological assessment of patients with a long-term diagnosis of human immunodeficiency virus infection and Candida oral colonization

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    The objective of this study was to evaluate Candida oral colonization in human immunodeficiency virus (HIV)-infected patients undergoing long-term highly active antiretroviral therapy (ARV). the cross-sectional study included 331 HIV patients, diagnosed from 1983 to 2003. Oral swabs were performed, and Candida species were determined using ID 32C. Isolates were tested for antifungal susceptibility. Clinical and laboratory data were collected to identify the association with Candida colonization. in total, 161 Candida isolates were detected among 147 of the 331 patients (44%), independently of the time when HIV infection was diagnosed. Candida albicans strains represented 137 (85%) of the isolates, and were susceptible to all of the tested antifungal drugs. Among the non-C. albicans strains, six isolates were dose-dependently susceptible to fluconazole, nine to itraconazole, and seven to ketoconazole. the isolation of Candida was significantly higher in patients with virological failure (83/147; p 0.0002) and CD4(+) T-lymphocyte counts < 200 cells/mm(3) (30/83; p 0.0003). Recovery of Candida in the oral cavity was independent of protease inhibitor (PI) usage (p 0.60). Colonized patients typically underwent salvage therapy (p 0.003), and had more episodes of opportunistic fungal infections (p 0.046) and malignancies (p 0.004). Oral Candida colonization in patients under ARV therapy was associated with the immunosupressed status of HIV-infected patients, i.e. low number of CD4(+) T-cells per cubic millimetre, failure of ARV therapy (salvage therapy), and higher number of opportunistic infections and malignancies. Despite the fact that PIs have in vitro antifungal activity, the use of this class of antiretroviral agent did not influence the presence of Candida in the oral cavity of AIDS patients.Univ Estadual Campinas, Dept Internal Med, Fac Med Sci, Div Infect Dis, BR-13081070 Campinas, SP, BrazilUniversidade Federal de SĂŁo Paulo, Div Infect Dis, SĂŁo Paulo, BrazilChiba Univ, Med Mycol Res Ctr, Chiba, JapanUniversidade Federal de SĂŁo Paulo, Div Infect Dis, SĂŁo Paulo, BrazilWeb of Scienc

    New Particles from Belle

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    I report recent results on hidden charm spectroscopy from Belle. These include: observation of a near-threshold enhancement in the omega-J/psi invariant mass distribution for exclusive B-->K omega J/psi decays; evidence for the decay X(3872)-->pi+pi-pi0 J/psi, where the pi+pi-pi0 invariant mass distribution has a strong peak between 750 MeV and the kinematic limit of 775 MeV, suggesting that the process is dominated by the sub-threshold decay X-->omega J/psi; and the observation of a peak near 3940 MeV in the J/psi recoil mass spectrum for the inclusive continuum process e+e- --> J/psi X. The results are based on a study of a 287 fb-1 sample of e+e- annihilation data collected at center- of-mass energies around the Upsilon(4S) in the Belle detector at the KEKB collider.Comment: 10 pages 12 figures. Invited talk at the 1st meeting of the APS Topical Group on Hadronic Physics, Fermilab, October 24-26, 2004; revised to correct some reference

    Detection of Bursts from FRB 121102 with the Effelsberg 100-m Radio Telescope at 5 GHz and the Role of Scintillation

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    FRB 121102, the only repeating fast radio burst (FRB) known to date, was discovered at 1.4 GHz and shortly after the discovery of its repeating nature, detected up to 2.4 GHz. Here we present three bursts detected with the 100-m Effelsberg radio telescope at 4.85 GHz. All three bursts exhibited frequency structure on broad and narrow frequency scales. Using an autocorrelation function analysis, we measured a characteristic bandwidth of the small-scale structure of 6.4±\pm1.6 MHz, which is consistent with the diffractive scintillation bandwidth for this line of sight through the Galactic interstellar medium (ISM) predicted by the NE2001 model. These were the only detections in a campaign totaling 22 hours in 10 observing epochs spanning five months. The observed burst detection rate within this observation was inconsistent with a Poisson process with a constant average occurrence rate; three bursts arrived in the final 0.3 hr of a 2 hr observation on 2016 August 20. We therefore observed a change in the rate of detectable bursts during this observation, and we argue that boosting by diffractive interstellar scintillations may have played a role in the detectability. Understanding whether changes in the detection rate of bursts from FRB 121102 observed at other radio frequencies and epochs are also a product of propagation effects, such as scintillation boosting by the Galactic ISM or plasma lensing in the host galaxy, or an intrinsic property of the burst emission will require further observations.Comment: Accepted to ApJ. Minor typos correcte

    Alterations in Mucin Expression in Ovarian Mucinous Tumors: Immunohistochemical Analysis of MUC2, MUC5AC, MUC6, and CD10 Expression

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    The aim of this study was to evaluate the immunohistochemical expression of MUC2, MUC5AC, MUC6, and CD10 in ovarian mucinous adenoma (MA), mucinous borderline tumor (MB), and mucinous adenocarcinoma (MC), and to analyze the relationship between prognosis and these expressions. The expression of MUC2, MUC5AC, MUC6, and CD10 was evaluated by immunohistochemical analysis in 29 cases of MA, 29 cases of MB, and 26 cases of MC and scored based on the percentage of positive cells. Moreover, the ovarian mucinous tumors were classified into 4 phenotypes based on the staining patterns: intestinal, gastrointestinal, gastric, and unclassified patterns. The gastrointestinal pattern and the expression of MUC2 and CD10 increased from MA to MC. Conversely, the gastric pattern and MUC5AC expression decreased from MA to MC. Low MUC2 expression in MC was correlated with a better long-term survival rate. MUC2 expression in MC may be a useful predictor of the clinical outcome. The expression patterns of MUC2, MUC5AC, MUC6, and CD10 indicated that intestinal metaplasia may arise from the gastric-like epithelium in MA and that a close association exists between carcinogenesis and intestinal metaplasia in major ovarian mucinous tumors
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