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  • 1
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    The CHANDRA HETGS X-ray Grating Spectrum of Eta Carinae (2001)
    In:  CASI
    Details
    Publikationsdatum: 2013-08-29
    Beschreibung: Eta Carinae may be the most massive and luminous star in the Galaxy and is suspected to be a massive, colliding wind binary system. The CHANDRA X-ray observatory has obtained a calibrated, high-resolution X-ray spectrum of the star uncontaminated by the nearby extended soft X-ray emission. Our 89 ksec CHANDRA observation with the High Energy Transmission Grating Spectrometer (HETGS) shows that the hot gas near the star is non-isothermal. The temperature distribution may represent the emission on either side of the colliding wind bow shock, effectively 'resolving' the shock. If so, the pre-shock wind velocities are approximately 700 and 1800 km/s in our analysis, and these velocities may be interpreted as the terminal velocities of the winds from 71 Carinae and from the hidden companion star. The forbidden-to-intercombination line ratios for the He-like ions of S, Si, and Fe are large, indicating that the line forming region lies far from the stellar photosphere. The iron fluorescent line at 1.93 angstroms, first detected by ASCA, is clearly resolved from the thermal iron line in the CHANDRA grating spectrum. The Fe fluorescent line is weaker in our CHANDRA observation than in any of the ASCA spectra. The CHANDRA observation also provides the first high-time resolution lightcurve of the uncontaminated stellar X-ray emission from 77 Carinae and shows that there is no significant, coherent variability during the CHANDRA observation. The 77 Carinae CHANDRA grating spectrum is unlike recently published X-ray grating spectra of single massive stars in significant ways and is generally consistent with colliding wind emission in a massive binary.
    Schlagwort(e): Astronomy
    Format: application/pdf
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  • 2
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    Measurement of the small-scale structure of the intergalactic medium using close quasar pairs (2017)
    American Association for the Advancement of Science (AAAS)
    In: Science
    Details
    Publikationsdatum: 2017-04-28
    Beschreibung: The distribution of diffuse gas in the intergalactic medium (IGM) imprints a series of hydrogen absorption lines on the spectra of distant background quasars known as the Lyman-α forest. Cosmological hydrodynamical simulations predict that IGM density fluctuations are suppressed below a characteristic scale where thermal pressure balances gravity. We measured this pressure-smoothing scale by quantifying absorption correlations in a sample of close quasar pairs. We compared our measurements to hydrodynamical simulations, where pressure smoothing is determined by the integrated thermal history of the IGM. Our findings are consistent with standard models for photoionization heating by the ultraviolet radiation backgrounds that reionized the universe.
    Schlagwort(e): Astronomy
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Geologie und Paläontologie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Publiziert von American Association for the Advancement of Science (AAAS)
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  • 3
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    Aortic wave reflection and input impedance as a function of posture in a chronic primate model (1992)
    In:  Other Sources
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    Publikationsdatum: 2011-08-24
    Beschreibung: No abstract available
    Schlagwort(e): Life Sciences (General)
    Materialart: The Physiologist (ISSN 0031-9376); Volume 35; 1 Suppl; S53-4
    Format: text
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  • 4
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    A homolog of an Escherichia coli phosphate-binding protein gene from Xanthomonas oryzae pv. oryzae (1995)
    In:  Other Sources
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    Publikationsdatum: 2011-08-24
    Beschreibung: A Xanthomonas oryzae pv. oryzae gene with sequence similarity to an Escherichia coli phosphate-binding protein gene (phoS) produces a periplasmic protein of apparent M(r) 35,000 when expressed in E. coli. Amino terminal sequencing revealed that a signal peptide is removed during transport to the periplasm in E. coli.
    Schlagwort(e): Life Sciences (General)
    Materialart: DNA sequence : the journal of DNA sequencing and mapping (ISSN 1042-5179); Volume 5; 5; 299-305
    Format: text
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  • 5
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    Molecular microbial diversity of a spacecraft assembly facility (2001)
    In:  Other Sources
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    Publikationsdatum: 2011-08-24
    Beschreibung: In ongoing investigations to map and archive the microbial footprints in various components of the spacecraft and its accessories, we have examined the microbial populations of the Jet Propulsion Laboratory's Spacecraft Assembly Facility (JPL-SAF). Witness plates made up of spacecraft materials, some painted with spacecraft qualified paints, were exposed for approximately 7 to 9 months at JPL-SAF and examined the particulate materials collected for the incidence of total cultivable aerobic heterotrophs and heat-tolerant (80 degrees C for 15-min.) spore-formers. The results showed that the witness plates coated with spacecraft qualified paints attracted more dust particles than the non-coated stainless steel witness plates. Among the four paints tested, witness plates coated with NS43G accumulated the highest number of particles, and hence attracted more cultivable microbes. The conventional microbiological examination revealed that the JPL-SAF harbors mainly Gram-positive microbes and mostly spore-forming Bacillus species. Most of the isolated microbes were heat resistant to 80 degrees C and proliferate at 60 degrees C. The phylogenetic relationships among 23 cultivable heat-tolerant microbes were examined using a battery of morphological, physiological, molecular and chemotaxonomic characterizations. By 16S rDNA sequence analysis, the isolates fell into seven clades: Bacillus licheniformis, B. pumilus, B. cereus, B. circulans, Staphylococcus capitis, Planococcus sp. and Micrococcus lylae. In contrast to the cultivable approach, direct DNA isolation, cloning and 16S rDNA sequencing analysis revealed equal representation of both Gram-positive and Gram-negative microorganisms.
    Schlagwort(e): Life Sciences (General)
    Materialart: Systematic and applied microbiology (ISSN 0723-2020); Volume 24; 2; 311-20
    Format: text
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  • 6
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    Polyphasic taxonomy of the genus Shewanella and description of Shewanella oneidensis sp. nov (1999)
    In:  Other Sources
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    Publikationsdatum: 2011-08-24
    Beschreibung: The genus Shewanella has been studied since 1931 with regard to a variety of topics of relevance to both applied and environmental microbiology. Recent years have seen the introduction of a large number of new Shewanella-like isolates, necessitating a coordinated review of the genus. In this work, the phylogenetic relationships among known shewanellae were examined using a battery of morphological, physiological, molecular and chemotaxonomic characterizations. This polyphasic taxonomy takes into account all available phenotypic and genotypic data and integrates them into a consensus classification. Based on information generated from this study and obtained from the literature, a scheme for the identification of Shewanella species has been compiled. Key phenotypic characteristics were sulfur reduction and halophilicity. Fatty acid and quinone profiling were used to impart an additional layer of information. Molecular characterizations employing small-subunit 16S rDNA sequences were at the limits of resolution for the differentiation of species in some cases. As a result, DNA-DNA hybridization and sequence analyses of a more rapidly evolving molecule (gyrB gene) were performed. Species-specific PCR probes were designed for the gyrB gene and used for the rapid screening of closely related strains. With this polyphasic approach, in addition to the ten described Shewanella species, two new species, Shewanella oneidensis and 'Shewanella pealeana', were recognized; Shewanella oneidensis sp. nov. is described here for the first time.
    Schlagwort(e): Life Sciences (General)
    Materialart: International journal of systematic bacteriology (ISSN 0020-7713); Volume 49 Pt 2; 705-24
    Format: text
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  • 7
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    The dynamics of herpesvirus and polyomavirus reactivation and shedding in healthy adults: a 14-month longitudinal study (2003)
    In:  Other Sources
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    Publikationsdatum: 2011-08-24
    Beschreibung: Humans are infected with viruses that establish long-term persistent infections. To address whether immunocompetent individuals control virus reactivation globally or independently and to identify patterns of sporadic reactivation, we monitored herpesviruses and polyomaviruses in 30 adults, over 14 months. Epstein-Barr virus (EBV) DNA was quantitated in saliva and peripheral blood mononuclear cells (PBMCs), cytomegalovirus (CMV) was assayed in urine, and JC virus (JCV) and BK virus (BKV) DNAs were assayed in urine and PBMCs. All individuals shed EBV in saliva, whereas 67% had 〉or=1 blood sample positive for EBV. Levels of EBV varied widely. CMV shedding occurred infrequently but occurred more commonly in younger individuals (P〈.03). JCV and BKV virurias were 46.7% and 0%, respectively. JCV shedding was age dependent and occurred commonly in individuals 〉or=40 years old (P〈.03). Seasonal variation was observed in shedding of EBV and JCV, but there was no correlation among shedding of EBV, CMV, and JCV (P〉.50). Thus, adults independently control persistent viruses, which display discordant, sporadic reactivations.
    Schlagwort(e): Life Sciences (General)
    Materialart: The Journal of infectious diseases (ISSN 0022-1899); Volume 187; 10; 1571-80
    Format: text
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  • 8
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    The ROSAT variable sky (1996)
    In:  CASI
    Details
    Publikationsdatum: 2004-12-03
    Beschreibung: The spectral and timing characteristics from a sample, of 91 objects, of the variable sources obtained using the Kolmogorov-Smirnov test technique are presented. The data were extracted from the catalog constructed by White, Giommi and Angelini, the WGACAT, based on the pointed observations from the Rosat missions. The application of the test revealed more than 2400 individual variable candidates, with 'sq chi' greater than 12. The sample of these variable sources, mostly unidentified, probably contains many flare stars, a few cataclysmic variables and a possible transient source.
    Schlagwort(e): Astronomy
    Materialart: ; 645-646
    Format: text
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  • 9
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    Iron K Line Variability in the Low-Luminosity AGN NGC 4579 (2000)
    In:  CASI
    Details
    Publikationsdatum: 2009-11-16
    Beschreibung: We present results of new ASCA observations of the low-luminosity AGN (LLAGN) NGC 4579 obtained in 1998 December 18 and 28, and we report on detection of variability of an iron K emission line. The X-ray luminosities in the 2-10 keV band for the two observations are nearly identical, L(sub X) approximately = 2 x 10(exp 4l) ergs/s, but they are approximately 35% larger than that measured in 1995 July by Terashima et al. (1998). An Fe K emission line is detected at 6.39 +/- 0.09 keV (source rest frame) which is lower than the line energy 6.73(sup +0.13, sub -0.12) keV in the 1995 observation. If we fit the Fe lines with a blend of two Gaussians centered at 6.4 keV and 6.73 KeV, the intensity of the 6.7 keV line decreased, while the intensity of the 6.4 keV line increased, within an interval of 3.5 years. This variability rules out thermal plasmas in the host galaxy as the origin of the ionized Fe line in this LLAGN. The detection and variability of the 6.4 keV line suggest that an optically thick standard accretion disk is present and subtends a large solid angle viewed from the nucleus at the Eddington ratio of L(sub Bol)/L(sub Eddington) approximately 2 x 10(exp -3) (Ho 1999). A broad disk-line profile is not clearly seen and the structure of the innermost part of accretion disk remains unclear.
    Schlagwort(e): Astronomy
    Format: text
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  • 10
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    Initial clinical experience of real-time three-dimensional echocardiography in patients with ischemic and idiopathic dilated cardiomyopathy (1999)
    In:  Other Sources
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    Publikationsdatum: 2011-08-24
    Beschreibung: The geometry of the left ventricle in patients with cardiomyopathy is often sub-optimal for 2-dimensional ultrasound when assessing left ventricular (LV) function and localized abnormalities such as a ventricular aneurysm. The aim of this study was to report the initial experience of real-time 3-D echocardiography for evaluating patients with cardiomyopathy. A total of 34 patients were evaluated with the real-time 3D method in the operating room (n = 15) and in the echocardiographic laboratory (n = 19). Thirteen of 28 patients with cardiomyopathy and 6 other subjects with normal LV function were evaluated by both real-time 3-D echocardiography and magnetic resonance imaging (MRI) for obtaining LV volumes and ejection fractions for comparison. There were close relations and agreements for LV volumes (r = 0.98, p 〈0.0001, mean difference = -15 +/- 81 ml) and ejection fractions (r = 0.97, p 〈0.0001, mean difference = 0.001 +/- 0.04) between the real-time 3D method and MRI when 3 cardiomyopathy cases with marked LV dilatation (LV end-diastolic volume 〉450 ml by MRI) were excluded. In these 3 patients, 3D echocardiography significantly underestimated the LV volumes due to difficulties with imaging the entire LV in a 60 degrees x 60 degrees pyramidal volume. The new real-time 3D echocardiography is feasible in patients with cardiomyopathy and may provide a faster and lower cost alternative to MRI for evaluating cardiac function in patients.
    Schlagwort(e): Life Sciences (General)
    Materialart: The American journal of cardiology (ISSN 0002-9149); Volume 84; 9; 1068-73
    Format: text
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