585 research outputs found

    GRB Observed by IBIS/PICsIT in the MeV Energy Range

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    We present the preliminary results of a systematic search for GRB and other transients in the publicly available data for the IBIS/PICsIT (0.2-10 MeV) detector on board INTEGRAL. Lightcurves in 2-8 energy bands with time resolution from 1 to 62.5 ms have been collected and an analysis of spectral and temporal characteristics has been performed. This is the nucleus of a forthcoming first catalog of GRB observed by PICsIT.Comment: 6 pages, 3 figures. Poster presented at COSPAR 2008. Advaces in Space Research, accepted for publicatio

    The first gamma-ray outburst of a Narrow-Line Seyfert 1 Galaxy: the case of PMN J0948+0022 in July 2010

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    We report on a multiwavelength campaign on the radio-loud Narrow-Line Seyfert 1 (NLS1) Galaxy PMN J0948+0022 (z=0.5846) performed in 2010 July-September and triggered by a high-energy gamma-ray outburst observed by the Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope. The peak flux in the 0.1-100 GeV energy band exceeded, for the first time in this type of source, the value of 10^-6 ph cm^-2 s^-1, corresponding to an observed luminosity of 10^48 erg s^-1. Although the source was too close to the Sun position to organize a densely sampled follow-up, it was possible to gather some multiwavelength data that confirmed the state of high activity across the sampled electromagnetic spectrum. The comparison of the spectral energy distribution of the NLS1 PMN J0948+0022 with that of a typical blazar - like 3C 273 - shows that the power emitted at gamma rays is extreme.Comment: 8 pages, 7 figures, 2 tables. Accepted for the publication on MNRAS Main Journal. Typo in bibliography correcte

    Optical and infrared photometry of the blazar PKS0537-441

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    We present a large collection of photometric data on the Blazar PKS 0537-441 in the VRIJHK bands taken in 2004-2009. At least three flare-like episodes with months duration, and >3 mag amplitude are apparent. The spectral energy distribution is consistent with a power law, and no indication of a thermal component is found. We searched for short time scale variability, and an interesting event was identified in the J band, with a duration of ~25 minutes.Comment: 10 pages, 3 figures, in press in ApJ

    Ketamine for Postpartum Depression: A Systematic Review

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    The purpose of this review is to explore perinatal ketamine’s potential for reducing postpartum depression after cesarean section. Articles reviewed from Pubmed, Cochrane, and Web of Science using specific search terms. 8 final papers were used for review after excluding duplicates and irrelevant titles and abstracts. Ketamine showed potential in reducing postpartum depression symptoms post C-section, although some studies reported no significant effects. All studies were randomized control trials. Ketamine may help prevent or lessen postpartum depression symptoms post C-section, but more research is needed to understand dosing and its casual relationship with PPD in this context

    Radio jet emission from GeV-emitting narrow-line Seyfert 1 galaxies

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    We studied the radio emission from four radio-loud and gamma-ray-loud narrow-line Seyfert 1 galaxies. The goal was to investigate whether a relativistic jet is operating at the source, and quantify its characteristics. We relied on the most systematic monitoring of such system in the cm and mm radio bands which is conducted with the Effelsberg 100 m and IRAM 30 m telescopes and covers the longest time-baselines and the most radio frequencies to date. We extract variability parameters and compute variability brightness temperatures and Doppler factors. The jet powers were computed from the light curves to estimate the energy output. The dynamics of radio spectral energy distributions were examined to understand the mechanism causing the variability. All the sources display intensive variability that occurs at a pace faster than what is commonly seen in blazars. The flaring events show intensive spectral evolution indicative of shock evolution. The brightness temperatures and Doppler factors are moderate, implying a mildly relativistic jet. The computed jet powers show very energetic flows. The radio polarisation in one case clearly implies a quiescent jet underlying the recursive flaring activity. Despite the generally lower flux densities, the sources appear to show all typical characteristics seen in blazars that are powered by relativistic jets.Comment: Accepted for publication in 4 - Extragalactic astronomy of Astronomy and Astrophysic

    Variable X-ray Absorption toward Gravitationally-Lensed Blazar PKS1830-211

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    We present X-ray spectral analysis of five Chandra and XMM-Newton observations of the gravitationally-lensed blazar PKS1830-211 from 2000 to 2004. We show that the X-ray absorption toward PKS1830-211 is variable, and the variable absorption is most likely to be intrinsic with amplitudes of about 2-30e22 cm^-2 depending on whether or not the absorber is partially covering the X-ray source. Our results confirm the variable absorption observed previously, although interpreted differently, in a sequence of ASCA observations. This large variation in the absorption column density can be interpreted as outflows from the central engine in the polar direction, consistent with recent numerical models of inflow/outflows in AGNs. In addition, it could possibly be caused by the interaction between the blazar jet and its environment, or the variation from the geometric configuration of the jet. While the spectra can also be fitted with a variable absorption at the lens redshift, we show that this model is unlikely. We also rule out the simple microlensing interpretation of variability which was previously suggested.Comment: 15 pages, 4 figures, Accepted to A

    Relativistic jets in Narrow-Line Seyfert 1

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    Narrow-Line Seyfert 1 (NLS1) class of active galactic nuclei (AGNs) is generally radio-quiet, but a small percent of them are radio-loud. The recent discovery by Fermi/LAT of high-energy gamma-ray emission from 4 NLS1s proved the existence of relativistic jets in these systems. It is therefore important to study this new class of gamma-ray emitting AGNs. Here we report preliminary results about the observations of the July 2010 gamma-ray outburst of PMN J0948+0022, when the source flux exceeded for the first time 10^-6 ph cm^-2 s^-1 (E > 100 MeV).Comment: 2 pages, 1 figure. To be presented at IAU Symposium 275 "Jets at all scales", Buenos Aires, 13-17 September 201

    Comparison of Cytogenetic and Static Cytometry Procedures in the Evaluation of Potentially Malignant Oral Lesions

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    Gross genomic damage or specific chromosomal alterations have been revealed by different laboratory procedures in potentially malignant oral lesions, but two or more procedures have never been applied at the same time to the same cell population. In the present study we considered cell suspensions obtained from 34 oral lesions at risk of malignancy to see whether they might harbour genetic alterations and whether a correlation exists between the results obtained by two different methods of assessing DNA aberrations. Each suspension underwent DNA-content assessment by static cytometry, and cytogenetic G-banding analysis of short-term primary cultures. DNA content was determined in a minimum of 1000 cells on a Fairfield ploidy analyser and results expressed as percent of aneuploid cells in the S-phase; cytogenetic analysis was carried out according to standard procedures on in situ G-banding metaphases, and results expressed as percent of metaphases with chromosomal alterations. The results showed that the percentage of metaphases with chromosomal alterations was significantly correlated with the percentage of aneuploid cells in the S-phase. In conclusion, genetic alterations can be revealed in the same oral specimen either by procedures studying DNA content in fixed cells or by procedures investigating chromosomal alterations in cultured and proliferating cells
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