933 research outputs found
D-Brane Interactions in a Gravitational Shock Wave Background
We study D-branes in the background of a gravitational shock wave. We
consider the case of parallel D-branes located on opposite sides with respect
to the shock wave. Their interaction is studied by evaluating the cylinder
diagram using the boundary states technique. Boundary states are defined at
each D-brane and their scalar product is evaluated after propagation through
the shock wave. Taking the limit where the gravitational shock wave vanishes we
show that the amplitude evaluated is consistent with the flat space-time
result.Comment: To be published in Modern Physics Letters A, revised version with
references added, 12 page
The Visible and Near Infrared module of EChO
The Visible and Near Infrared (VNIR) is one of the modules of EChO, the
Exoplanets Characterization Observatory proposed to ESA for an M-class mission.
EChO is aimed to observe planets while transiting by their suns. Then the
instrument had to be designed to assure a high efficiency over the whole
spectral range. In fact, it has to be able to observe stars with an apparent
magnitude Mv= 9-12 and to see contrasts of the order of 10-4 - 10-5 necessary
to reveal the characteristics of the atmospheres of the exoplanets under
investigation. VNIR is a spectrometer in a cross-dispersed configuration,
covering the 0.4-2.5 micron spectral range with a resolving power of about 330
and a field of view of 2 arcsec. It is functionally split into two channels
respectively working in the 0.4-1 and 1.0-2.5 micron spectral ranges. Such a
solution is imposed by the fact the light at short wavelengths has to be shared
with the EChO Fine Guiding System (FGS) devoted to the pointing of the stars
under observation. The spectrometer makes use of a HgCdTe detector of 512 by
512 pixels, 18 micron pitch and working at a temperature of 45K as the entire
VNIR optical bench. The instrument has been interfaced to the telescope optics
by two optical fibers, one per channel, to assure an easier coupling and an
easier colocation of the instrument inside the EChO optical bench.Comment: 26 page
Impact of IFN lambda 3/4 single nucleotide polymorphisms on the cytomegalovirus reactivation in autologous stem cell transplant patients
Cytomegalovirus (CMV) infection represents one of the main cause mortality after Stem Cell Transplantation. Recently, a protective effect of the T allele of rs12979860 IL28B Single Nucleotide Polymorphisms (SNPs) against CMV infection in the allogenic stem cell transplantation was suggested. We investigate whether the rs12979860 IL28B SNP and the relative rs368234815 (IFNλ4) genotype may affect the incidence of active CMV infection in Autologous stem cell transplantation (Auto-SCT) setting. The study included 99 patients who underwent to Auto-SCT. IL28 and IFNÎ4 SNPs were correlated with CMV reactivation along with other clinical and treatment parameters. CMV reactivation by CMV DNAemia was evaluated once a week until day 100 from Auto-SCT. CMV reactivation was documented in 50% (TT-ÎG/ÎG), 35% (CC-TT/TT) and 29.2% (CT-TT/ÎG) of the patients respectively. No differences in CMV copies number were recorded at reactivation between different IL28/IFNλ4 genotypes. The analysis of patients older than 60 years showed a significantly higher incidence of active CMV infection in the TT-ÎG/ÎG (83%) population with respect to CC-TT/TT (21%) and CT-TT/ÎG (40%) patients. Our data suggest a negative role of TT-ÎG/ÎG genotype in the CMV reactivation in Auto-SCT. The exposure to rituximab and the pre-infusion presence of anti CMV IgG also significantly influenced CMV reactivation
Stationary waves and slowly moving features in the night upper clouds of Venus
At the cloud top level of Venus (65-70 km altitude) the atmosphere rotates 60
times faster than the underlying surface, a phenomenon known as superrotation.
Whereas on Venus's dayside the cloud top motions are well determined and Venus
general circulation models predict a mean zonal flow at the upper clouds
similar on both day and nightside, the nightside circulation remains poorly
studied except for the polar region. Here we report global measurements of the
nightside circulation at the upper cloud level. We tracked individual features
in thermal emission images at 3.8 and 5.0 obtained between
2006 and 2008 by the Visible and Infrared Thermal Imaging Spectrometer
(VIRTIS-M) onboard Venus Express and in 2015 by ground-based measurements with
the Medium-Resolution 0.8-5.5 Micron Spectrograph and Imager (SpeX) at the
National Aeronautics and Space Administration Infrared Telescope Facility
(NASA/IRTF). The zonal motions range from -110 to -60 m s, consistent
with those found for the dayside but with larger dispersion. Slow motions (-50
to -20 m s) were also found and remain unexplained. In addition,
abundant stationary wave patterns with zonal speeds from -10 to +10 m s
dominate the night upper clouds and concentrate over the regions of higher
surface elevation.Comment: 15 pages, 4 figures, 6 supplementary figure
Two-year observations of the Jupiter polar regions by JIRAM on board Juno
We observed the evolution of Jupiter's polar cyclonic structures over two years between February 2017 and February 2019, using polar observations by the Jovian InfraRed Auroral Mapper, JIRAM, on the Juno mission. Images and spectra were collected by the instrument in the 5âÎŒm wavelength range. The images were used to monitor the development of the cyclonic and anticyclonic structures at latitudes higher than 80° both in the northern and the southern hemispheres. Spectroscopic measurements were then used to monitor the abundances of the minor atmospheric constituents water vapor, ammonia, phosphine and germane in the polar regions, where the atmospheric optical depth is less than 1. Finally, we performed a comparative analysis with oceanic cyclones on Earth in an attempt to explain the spectral characteristics of the cyclonic structures we observe in Jupiter's polar atmosphere
Ultrasonographic diagnosis of placenta accreta spectrum (PAS) disorder: Ideation of an ultrasonographic score and correlation with surgical and neonatal outcomes
The objective of this study was to evaluate a novel ultrasonographic scoring system for the diagnosis of PAS and the prediction of maternal and neonatal outcomes. In this retrospective study, 138 patients with at least one previous caesarean section (CS) and placenta previa were included. They were divided into four groups ranging from Group 0 (Non PAS) to Group 3 (Placenta Percreta) according to the histological or surgical confirmation. Their ultrasound examinations during pregnancy were reviewed according to the nine different ultrasound signs reported by the European Working Group on Abnormally Invasive Placenta. For each parameter, 0 to 2 points were assigned. The sum of the points reflects the severity of PAS with a maximum score of 20. The scoring system revealed good performances in evaluation metrics, with an overall accuracy of 94%. In addition to this, patientsâ characteristics and surgical and neonatal outcomes were analyzed with an evidence of higher incidence of complications in severe forms. Our study suggests that antenatal ultrasonographic diagnosis of PAS is feasible with sufficient level of accuracy. This will be important in identifying high-risk patients and implementing preventive strategy
The role of SARS-COV-2 infection in promoting abnormal immune response and sepsis: A comparison between SARS-COV-2-related sepsis and sepsis from other causes
Background: COVID-19 caused by SARS-CoV-2 virus is characterized by respiratory compromise and immune
system involvement, even leading to serious disorders, such as cytokine storm.
Methods: We then conducted a literature review on the topic of sepsis and covid-19, and in parallel conducted an
experimental study on the histological finding of patients who died from SARS-Covid 19 infection and a control
group.
Results: Sepsis associated with covid-19 infection has some similarities and differences from that from other
causes.
Conclusion: In this paper the complex interplay between the 2 disorders was discussed, focusing on the similarities
and on the effect that one could have on the other. A preliminary experimental section that demonstrates the
multisystemic involvement in subjects who die from SARS-CoV-2 is also proposed
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