338 research outputs found
Four Years of Extreme Ultraviolet Observations of Markarian 421: II. Temporal Analysis
The Extreme Ultraviolet Explorer (EUVE) satellite accumulated ~one million
seconds of public data between 1994 and 1997 for the BL Lacertae object
Markarian 421. This is the second of two papers in which we present the results
of spectral and temporal analysis of this EUVE data set. We analyze in the
present paper the imaging data by means of power spectrum and structure
function techniques, while the spectral analysis is presented in a companion
paper. We find for MRK 421 a power spectrum with slope -2.14 +- 0.28 with a
break at ~3 days. This is the first time that a break in the power spectrum of
a BL Lacertae object has been found. We also find evidence of non-stationarity
for MRK 421 EUV emissionComment: Accepted for publication in the Astrophysical Journal. 16 pages, 14
Postscript figures, 3 Table
Prediction of hearing recovery in sudden deafness treated with intratympanic steroids
The present study aims to obtain a probability model allowing the prediction of the auditory recovery in patients affected by sudden sensorineural hearing loss treated exclusively with intratympanic steroids. A monocentric retrospective chart review of three-hundred eighty-one patients has been performed. A Probit model was used to investigate the correlation between the success of the treatment (marked or total recovery according to Furuashi's criteria), and the delay between the onset of disease and the beginning of therapy. The age of the patients and the audiometric curve shapes were included in the analysis. Results show that delay is negatively correlated with the variable success. Considering the entire sample, each day of delay decreases by 3% the probability of success. The prediction model shows that for every day that passes from the onset of the disease the probability of success declines in absence of the medical treatment, hence we conclude that early treatment is strongly recommended
Emotion-based analysis of programming languages on Stack Overflow
When developing a software engineering project, selecting the most appropriate programming language is a crucial step. Most often, feeling at ease with the possible options becomes almost as relevant as the technical features of the language. Therefore, it appears to be worth analyzing the role that the emotional component plays in this process. In this article, we analyze the trend of the emotions expressed by developers in 2018 on the Stack Overflow platform in posts concerning 26 programming languages. To do so, we propose a learning model trained by distant supervision and the comparison of two different classifier architectures
The BeppoSAX view of the hard X-ray background
First results on a medium-deep X-ray survey in the "new" 5-10 keV band
carried out with the MECS detectors onboard BeppoSAX are presented. The High
Energy Llarge Area Survey (HELLAS) is aimed to directly explore a band where
the energy density of the X-ray background is more than twice than that in the
soft (0.5-2.0 keV) band. The optical identification follow-up of the first ten
HELLAS hard X-ray sources indicate that Active Galactic Nuclei are the dominant
population at 5-10 keV fluxes of the order of 10e-13 cgs. We discuss the
implications of these findings for the AGN synthesis models for the XRB.Comment: 6 pages, 4 figures, uses psfig.sty. Accepted for publication in
Advances in Space Research, Proceedings of the 32nd Scientific Assembly of
COSPA
A Medium Survey of the Hard X-Ray Sky with ASCA. II.: The Source's Broad Band X-Ray Spectral Properties
A complete sample of 60 serendipitous hard X-ray sources with flux in the
range \ecs to \ecs (2 - 10
keV), detected in 87 ASCA GIS2 images, was recently presented in literature.
Using this sample it was possible to extend the description of the 2-10 keV
LogN(>S)-LogS down to a flux limit of \ecs (the
faintest detectable flux), resolving about a quarter of the Cosmic X-ray
Background. In this paper we have combined the ASCA GIS2 and GIS3 data of these
sources to investigate their X-ray spectral properties using the "hardness"
ratios and the "stacked" spectra method. Because of the sample statistical
representativeness, the results presented here, that refer to the faintest hard
X-ray sources that can be studied with the current instrumentation, are
relevant to the understanding of the CXB and of the AGN unification scheme.Comment: 28 pages plus 6 figures, LaTex manuscript, Accepted for publication
in the Astrophysical Journal, Figure 5 can retrieved via anonymous ftp at
ftp://ftp.brera.mi.astro.it/pub/ASCA/paper2/fig5.ps.g
Reduced number and function of peripheral dendritic cells in coeliac disease.
Dendritic cells (DC) play a pivotal role in shaping the immune response in
both physiological and pathological conditions. In peripheral blood at least
two subsets, the myeloid and plasmacytoid, have been described as having
different T stimulatory functions and a variable degree of maturation. Certainly,
antigen presentation plays a crucial role in the pathogenesis of coeliac
disease and circulating immune cells are thought to reflect the state of
immune response within the gut. Therefore,we aimed to investigate the quantitative
and phenotypical modifications of peripheral bloodDC, together with
their functional properties, in this pathological condition. Blood samples
from 11 untreated patients before and after a course of gluten-free diet, 27
treated patients and 14 controls underwent flow-cytometric analysis, while
immunomagnetically sorted DC from the CD patients and eight human leucocyte
antigen (HLA)-DQ2/8+ bone marrow donors were used to evaluate
maturation status through the CD83 expression, cytokine profile for interleukin
(IL)-6, IL-10, IL-12 and interferon (IFN)-a by enzyme-linked immunosorbent
assay (ELISA), and functional properties by mixed leucocyte reaction
before and after pulsing with digested gliadin. We found that in both
untreated and treated patients, a significant reduction of the entire DC population,
mainly the plasmacytoid subset, in comparison to healthy controls was
observed. In active disease, an impaired allogenic lymphocyte reaction and a
significant reduction of IFN-a production, paralleled by the presence of a
more immature status, were also demonstrated. All the latter modifications
have been reverted by pulsing DC with digested gliadin
Testing current synthesis models of the X-ray background
We present synthesis models of the X-ray background where the available X-ray
observational constraints are used to derive information on the AGN population
properties. We show the need for luminous X-ray absorbed AGNs, the QSO2s, in
reproducing the 2-10 keV source counts at relatively bright fluxes. We compare
a model where the evolution of absorbed AGNs is faster than that of unabsorbed
ones, with a standard model where absorbed and unabsorbed AGNs evolve at the
same rate. It is found that an increase by a factor of ~2 from z=0 to z~1.3 in
the ratio between absorbed and unabsorbed AGNs would provide a significant
improvement in the data description. Finally, we make predictions on the AGNs
to be observed in deep X-ray surveys which contain information on the AGN space
density at high redshift.Comment: 11 pages with 8 figures, A&A accepte
Resolving the extragalactic hard X-ray background
The origin of the hard (2-10 keV) X-ray background has remained mysterious
for over 35 years. Most of the soft (0.5-2 keV) X-ray background has been
resolved into discrete sources, which are primarily quasars; however, these
sources do not have the flat spectral shape required to match the X-ray
background spectrum. Here we report the results of an X-ray survey 30 times
more sensitive than previous studies in the hard band and four times more
sensitive in the soft band. The sources detected in our survey account for at
least 75 per cent of the hard X-ray background. The mean X-ray spectrum of
these sources is in good agreement with that of the background. The X-ray
emission from the majority of the detected sources is unambiguously associated
with either the nuclei of otherwise normal bright galaxies or optically faint
sources, which could either be active nuclei of dust enshrouded galaxies or the
first quasars at very high redshifts.Comment: Nature article in pres
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