585 research outputs found
GRB Observed by IBIS/PICsIT in the MeV Energy Range
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
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
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
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
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
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
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
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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