452 research outputs found
The spectral catalogue of INTEGRAL gamma-ray bursts: results of the joint IBIS/SPI spectral analysis
We present the updated INTEGRAL catalogue of gamma-ray bursts (GRBs) observed
between December 2002 and February 2012. The catalogue contains the spectral
parameters for 59 GRBs localized by the INTEGRAL Burst Alert System (IBAS). We
used the data from the two main instruments on board the INTEGRAL satellite:
the spectrometer SPI (SPectrometer on INTEGRAL) nominally covering the energy
range 18 keV - 8 MeV, and the imager IBIS (the Imager on Board the INTEGRAL
Satellite) operating in the range from 15 keV to 10 MeV. For the spectral
analysis we applied a new data extraction technique, developed in order to
explore the energy regions of highest sensitivity for both instruments, SPI and
IBIS. It allowed us to perform analysis of the GRB spectra over a broad energy
range and to determine the bursts' spectral peak energies. The spectral
analysis was performed on the whole sample of GRBs triggered by IBAS, including
all the events observed in period December 2002 - February 2012. The catalogue
contains the trigger times, burst coordinates, positional errors, durations and
peak fluxes for 28 unpublished GRBs observed between September 2008 and
February 2012. The light curves in 20 - 200 keV energy band of these events
were derived using IBIS data. We compare the prompt emission properties of the
INTEGRAL GRB sample with the BATSE and Fermi samples.Comment: 16 pages, 40 figures, accepted for publication in Astronomy &
Astrophysic
Are GRB 980425 and GRB 031203 real outliers or twins of GRB 060218?
GRB 980425 and GRB 031203 are apparently two outliers with respect to the
correlation between the isotropic equivalent energy E_iso emitted in the prompt
radiation phase and the peak frequency E_peak of the spectrum in a vF(v)
representation (the so-called Amati relation). We discuss if these two bursts
are really different from the others or if their location in the E_iso-E_peak
plane is the result of other effects, such as viewing them off-axis, or through
a scattering screen, or a misinterpretation of their spectral properties. The
latter case seems particularly interesting after GRB 060218, that, unlike GRB
031203 and GRB 980425, had a prompt emission detected both in hard and soft
X-rays which lasted ~2800 seconds. This allowed to determine its E_peak and
total emitted energy. Although it shares with GRB 031203 the total energetics,
it is not an outlier with respect to the Amati correlation. We then investigate
if a hard-to-soft spectral evolution in GRB 031203 and GRB 980425, consistent
with all the observed properties, can give rise to a time integrated spectrum
with an E_peak consistent with the Amati relation.Comment: 13 pages, 9 figures, 2 tables. Accepted for publication in MNRA
Behind the dust curtain: the spectacular case of GRB 160623A
We report on the X-ray dust-scattering features observed around the afterglow
of the gamma ray burst GRB 160623A. With an XMM-Newton observation carried out
~2 days after the burst, we found evidence of at least six rings, with angular
size expanding between ~2 and 9 arcmin, as expected for X-ray scattering of the
prompt GRB emission by dust clouds in our Galaxy. From the expansion rate of
the rings, we measured the distances of the dust layers with extraordinary
precision: 528.1 +\- 1.2 pc, 679.2 +\- 1.9 pc, 789.0 +\- 2.8 pc, 952 +\- 5 pc,
1539 +\- 20 pc and 5079 +\- 64 pc. A spectral analysis of the ring spectra,
based on an appropriate dust-scattering model (BARE-GR-B from Zubko et al.
2004}) and the estimated burst fluence, allowed us to derive the column density
of the individual dust layers, which are in the range 7x10^20-1.5x10^22 cm^-2.
The farthest dust-layer (i.e. the one responsible for the smallest ring) is
also the one with the lowest column density and it is possibly very extended,
indicating a diffuse dust region. The properties derived for the six
dust-layers (distance, thickness, and optical depth) are generally in good
agreement with independent information on the reddening along this line of
sight and on the distribution of molecular and atomic gas.Comment: 9 pages, 10 figures, 1 table; accepted for publication in MNRA
Emerging evidence for Q fever in humans in Denmark: role of contact with dairy cattle
AbstractUntil recently, Q fever was notified in very low numbers annually in Denmark and it was always considered to be acquired abroad. Preliminary reports now describe Coxiella burnetii in milk samples from Danish dairy cattle. Serum samples of a large cohort of farmers, veterinarians, inseminators and hoof trimmers, all having occupational contact with dairy cattle, were tested for the presence of IgG to phase I and phase II antigens of C. burnetii. In 39 of 359 individuals studied (11%), the presence of antibodies to C. burnetii was found. Veterinarians had the highest seropositivity rate (36%). This survey suggests that C. burnetii is a recently recognized domestic infection in Denmark and that risk of infection is associated with occupation
Integrity and life estimation of turbine runner cover in a hydro power plant
This paper presents integrity and life estimation of turbine runner cover in a vertical pipe turbines,Kaplan 200 MW nominal output power, produced in Russia, and built in six hydro-generation units ofhydroelectric power plant âÄerdap 1â in Serbia. Fatigue and corrosion-fatigue interaction have been taken intoaccount using experimentally obtained material properties, as well as analytical and numerical calculations ofstress state, to estimate appropriate safety factors. Fatigue crack growth rate, da/dN, was also calculated,indicated that internal defects of circular or elliptical shape, found out by ultrasonic testing, do not affect reliableoperation of runner cover
Gene electrotransfer of IL-2 and IL-12 plasmids effectively eradicated murine B16.F10 melanoma
Gene therapy has become an important approach for treating cancer, and electroporation represents a technology for introducing therapeutic genes into a cell. An example of cancer gene therapy relying on gene electrotransfer is the use of immunomodulatory cytokines, such as interleukin 2 (IL-2) and 12 (IL-12), which directly stimulate immune cells at the tumour site. The aim of our study was to determine the effects of gene electrotransfer with two plasmids encoding IL-2 and IL-12 in vitro and in vivo. Two different pulse protocols, known as EP1 (600 V/cm, 5 ms, 1 Hz, 8 pulses) and EP2 (1300 V/cm, 100 ”s, 1 Hz, 8 pulses), were assessed in vitro for application in subsequent in vivo experiments. In the in vivo experiment, gene electrotransfer of pIL-2 and pIL-12 using the EP1 protocol was performed in B16.F10 murine melanoma. Combined treatment of tumours using pIL2 and pIL12 induced significant tumour growth delay and 71% complete tumour regression. Furthermore, in tumours coexpressing IL-2 and IL-12, increased accumulation of dendritic cells and M1 macrophages was obtained along with the activation of proinflammatory signals, resulting in CD4 + and CD8 + T-lymphocyte recruitment and immune memory development in the mice. In conclusion, we demonstrated high antitumour efficacy of combined IL-2 and IL-12 gene electrotransfer protocols in low-immunogenicity murine B16.F10 melanoma
\u3ci\u3eIn Vitro and In Vivo\u3c/i\u3e Correlation of Skin and Cellular Responses to Nucleic Acid Delivery
Skin, the largest organ in the body, provides a passive physical barrier against infection and contains elements of the innate and adaptive immune systems. Skin consists of various cells, including keratinocytes, fibroblasts, endothelial cells and immune cells. This diversity of cell types could be important to gene therapies because DNA transfection could elicit different responses in different cell types. Previously, we observed the upregulation and activation of cytosolic DNA sensing pathways in several non-tumor and tumor cell types as well in tumors after the electroporation (electrotransfer) of plasmid DNA (pDNA). Based on this research and the innate immunogenicity of skin, we correlated the effects of pDNA electrotransfer to fibroblasts and keratinocytes to mouse skin using reverse transcription real-time PCR (RT-qPCR) and several types of protein quantification. After pDNA electrotransfer, the mRNAs of the putative DNA sensors DEAD (AspGlu-Ala-Asp) box polypeptide 60 (Ddx60), absent in melanoma 2 (Aim2), Z-DNA binding protein 1 (Zbp1), interferon activated gene 202 (Ifi202), and interferon-inducible protein 204 (Ifi204) were upregulated in keratinocytes, while Ddx60, Zbp1 and Ifi204 were upregulated in fibroblasts. Increased levels of the mRNAs and proteins of several cytokines and chemokines were detected and varied based on cell type. Mouse skin experiments in vivo confirmed our in vitro results with increased expression of putative DNA sensor mRNAs and of the mRNAs and proteins of several cytokines and chemokines. Finally, with immunofluorescent staining, we demonstrated that skin keratinocytes, fibroblasts and macrophages contribute to the immune response observed after pDNA electrotransfer
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