205 research outputs found

    Experience with the Hubble Space Telescope: 20 years of an archetype

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    The Hubble Space Telescope's mission is summarized, with special emphasis placed on the Space Telescope Science Institute's unique experience with Hubble's behavior as an astronomical telescope in the environment of low earth orbit for over two decades. Historical context and background are given, and the project's early scientific expectations are described. A general overview of the spacecraft is followed by a more detailed look at the optical design, both as intended and as built. Basic characteristics of the complete complement of science instruments are also summarized. Experience with the telescope on-orbit is reviewed, starting with the major initial problems, solutions, human servicing missions, and the associated expansion of the observatory's capabilities over this time. Specific attention is then given to understanding Hubble's optical quality and pointing/jitter performance, two fundamental characteristics of a telescope. Experience with-and the important mitigation of-radiation damage and contamination is also related. Beyond the telescope itself, the advances in data reduction, calibration, and observing techniques are briefly discussed, as well as the subsequent emergence of highly accessible high-level archival science products. Hubble's scientific impact concludes the discussion.Comment: Also found at http://www.stsci.edu/institute/org/telescopes/Reports/LalloOE2012.pd

    Analysis of four new enterococcus faecalis phages and modeling of a hyaluronidase catalytic domain from saphexavirus

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    Background: Phage therapy (PT), as a method to treat bacterial infections, needs identification of bacteriophages targeting specific pathogenic host. Enterococcus faecalis, a Gram-positive coccus resident in the human gastrointestinal tract, may become pathogenic in hospitalized patients showing acquired resistance to vancomycin and thus representing a possible target for PT. Materials and Methods: We isolated four phages that infect E. faecalis and characterized them by host range screening, transmission electron microscopy, and genome sequencing. We also identified and three-dimensional modeled a new hyaluronidase enzyme. Results: The four phages belong to Siphoviridae family: three Efquatrovirus (namely vB_EfaS_TV51, vB_EfaS_TV54, and vB_EfaS_TV217) and one Saphexavirus (vB_EfaS_TV16). All of them are compatible with lytic cycle. vB_EfaS_TV16 moreover presents a gene encoding for a hyaluronidase enzyme. Conclusions: The identified phages show features suggesting their useful application in PT, particularly the Saphexavirus that may be of enhanced relevance in PT because of its potential biofilm-digestion capability

    Gestational age and hospital utilization : three-years follow-up of an area-based birth cohort

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    OBJECTIVE: To investigate differences by gestational age in emergency department visits and re-hospitalizations during the three years following childbirth discharge. METHODS: We performed a historical cohort study in Lazio Region, Italy, for infants born in 2007-2008 to resident mothers. Health administrative data were used. Analysis was performed by multinomial logistic regression. RESULTS: Of 90 545 infants, more than 50% had at least one emergency department visit, and 18.8% at least one re-hospitalization. After the exclusion of infants with congenital anomalies, relative risk ratios of re-hospitalization and, to a lesser extent, of emergency department visits increased by decreasing gestational age; the two events were also higher for mothers ≤35 years of age, with low education and of Italian nationality. Residency outside the metropolitan area was associated with an increased risk of re-hospitalization and a decreased risk of emergency department visits. CONCLUSION: During the three years following childbirth discharge, re-hospitalizations and, to a lesser extent, emergency department use are inversely related to gestational age at birth; socio-demographic factors have an effect on the risk of infant use of hospital resources independent of gestational age

    Analisis Zerumbone Dalam Zingiber Zerumbet Dan Aktivitas Penghambatannya Terhadap Bakteri Mycobacterium Tuberculosis: Analysis of Zerumbone in Zingiber Zerumbet and Inhibitory Activity Against Mycobacterium Tuberculosis

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    Zerumbone has been reported for their several biological activities. In our interest to this compound, we have identified and analyzed its content in Zingiber zerumbet, a medicinal plant from Indonesian traditional medicine and investigated its inhibitory activity against Mycobacterium tuberculosis, a known infection bacteria of tuberculosis. Analysis of zerumbone was performed with densitometry to leave, rhizome, flower, and stem of Z. zerumbet which was extracted with various solvent system and extraction methods to determine the best method to isolate zerumbone from Z. zerumbet. Result showed that the highest zerumbone was in rhizome while was not observed in other part. Analysis with various solvent and extraction methods showed the highest yield of zerumbone can be extracted by n-hexane (maceration) and reflux extraction method (methanol). Furthermore, inhibitory activity of zerumbone against M. tuberculosis was tested using Lowenstein Jensen medium by counting the number of M. tuberculosis colony growth in medium. Resulted inhibitory activity of zerumbone at all test concentration (0.5, 0.1, 0.05, 0.01, 0.005%) with the growth of 10, 12, 14, 15, and 50 colonies of M. tuberculosis was observed, respectively. This is indicate that zerumbone can be used as an alternative choice for treatment tuberculosis in the future

    A Year of Wavefront Sensing with JWST in Flight: Cycle 1 Telescope Monitoring and Maintenance Summary

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    We summarize JWST's measured telescope performance across science Cycle 1. The stability of segments alignments is typically better than 10 nanometers RMS between measurements every two days, leading to highly stable point spread functions. The frequency of segment "tilt events" decreased significantly, and larger tilt events ceased entirely, as structures gradually equilibrated after cooldown. Mirror corrections every 1-2 months now maintain the telescope below 70 nm RMS wavefront error. Observed micrometeoroid impacts during cycle 1 had negligible effect on science performance, consistent with preflight predictions. As JWST begins Cycle 2, its optical performance and stability are equal to, and in some ways better than, the performance reported at the end of commissioning.Comment: STScI Technical Memo. 2.5 pages text, 1 figur

    Performance of the Space Telescope Imaging Spectrograph after SM4

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    On May 17, 2009, during the fourth EVA of SM4, astronauts Michael Good and Mike Massimino replaced the failed LVPS-2 circuit board on the Space Telescope Imaging Spectrograph (STIS), restoring this HST instrument to operation after a nearly 6 year hiatus. STIS after this 2009 repair operates in much the same way as it did during the 2001-2004 period of operations with the Side-2 electronics. Internal and external alignments of the instrument are similar to what they had been in 2004, and most changes in performance are modest. The STIS CCD detector continued to experience radiation damage during the hiatus in operations, leading to decreased charge transfer efficiency (CTE) and an increased number of hot pixels. The sensitivities for most modes are surprisingly close to what was expected from simple extrapolation of the 2003-2004 trends, although the echelle modes show somewhat more complex behavior. The biggest surprise was that the dark count rate for the NUV MAMA detector after SM4 has been much larger than had been expected; it is currently about 2.5 times bigger than it was in 2004 and is only slowly decreasing. We discuss how these changes will affect science with STIS now and in the future

    Obstetric near-miss cases among women admitted to intensive care units in Italy

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    Objective. Maternal near-miss defines a narrow category of morbidity encompassing potentially life-threatening episodes. The purpose of this study was to detect near-miss instances among women admitted to intensive care units or coronary units, analyze associated causes, and compute absolute and specific maternal morbidity rates in six Italian regions. Design. Observational retrospective study. Setting. Six Italian regions representing 49% of all resident Italian women aged 15-49 years. Population. The study population included all pregnant women aged 15-49 years admitted to intensive care units or coronary care units in the participating regions. Cases were defined as women aged 15-49 years resident in the participating regions, with one or more hospitalizations in intensive care for pregnancy or any pregnancy outcome between 2004 and 2005. Methods. Cases were identified through the Hospital Discharge Database. Enrolled cases were diagnosed according to the 9th International Classification of Diseases. Main outcome measure. Maternal near-miss rate (number of women experiencing an admission to intensive care units/all women with live or stillborn babies). Results. A total of 1259 near-miss cases were identified and the total maternal near-miss rate was 2.0/1000 deliveries. Seventy percent of the women were admitted to intensive care units or coronary units after a cesarean section. The leading associated risk factors were obstetric hemorrhage/disseminated intravascular coagulation (40%) and hypertensive disorders of pregnancy (29%). Conclusions. Monitoring of near-miss morbidity in conjunction with mortality surveillance could help to identify effective preventive measures for potentially life-threatening episodes
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