395 research outputs found
Formal and Informal Volunteering and Health in Mediterranean Europe
In this paper, we compare the correlation among formal and informal volunteering and self-perceived health across Mediterranean European countries after controlling for socio-economic characteristics, housing features, neighborhood quality, size of municipality, social and cultural participation and regional dummies. We find that informal volunteering has a significant, positive correlation with self-perceived health in France, Spain, Greece and a significant, negative relationship in Italy
Afterglows from precursors in Gamma Ray Bursts. Application to the optical afterglow of GRB 091024
About 15% of Gamma Ray Bursts have precursors, i.e. emission episodes
preceding the main event, whose spectral and temporal properties are similar to
the main emission. We propose that precursors have their own fireball,
producing afterglow emission due to the dissipation of the kinetic energy via
external shock. In the time lapse between the precursor and the main event, we
assume that the central engine is not completely turned off, but it continues
to eject relativistic material at a smaller rate, whose emission is below the
background level. The precursor fireball generates a first afterglow by the
interaction with the external circumburst medium. Matter injected by the
central engine during the "quasi-quiescent" phase replenishes the external
medium with material in relativistic motion. The fireball corresponding to the
main prompt emission episode crashes with this moving material, producing a
second afterglow, and finally catches up and merges with the first precursor
fireball. We apply this new model to GRB 091024, an event with a precursor in
the prompt light curve and two well defined bumps in the optical afterglow,
obtaining an excellent agreement with the existing data.Comment: 11 pages, 6 figures, 3 tables. Accepted for publication in MNRAS,
Main Journa
Unveiling the population of orphan Gamma Ray Bursts
Gamma Ray Bursts are detectable in the gamma-ray band if their jets are
oriented towards the observer. However, for each GRB with a typical theta_jet,
there should be ~2/theta_jet^2 bursts whose emission cone is oriented elsewhere
in space. These off-axis bursts can be eventually detected when, due to the
deceleration of their relativistic jets, the beaming angle becomes comparable
to the viewing angle. Orphan Afterglows (OA) should outnumber the current
population of bursts detected in the gamma-ray band even if they have not been
conclusively observed so far at any frequency. We compute the expected flux of
the population of orphan afterglows in the mm, optical and X-ray bands through
a population synthesis code of GRBs and the standard afterglow emission model.
We estimate the detection rate of OA by on-going and forthcoming surveys. The
average duration of OA as transients above a given limiting flux is derived and
described with analytical expressions: in general OA should appear as daily
transients in optical surveys and as monthly/yearly transients in the mm/radio
band. We find that ~ 2 OA yr^-1 could already be detected by Gaia and up to 20
OA yr^-1 could be observed by the ZTF survey. A larger number of 50 OA yr^-1
should be detected by LSST in the optical band. For the X-ray band, ~ 26 OA
yr^-1 could be detected by the eROSITA. For the large population of OA
detectable by LSST, the X-ray and optical follow up of the light curve (for the
brightest cases) and/or the extensive follow up of their emission in the mm and
radio band could be the key to disentangle their GRB nature from other
extragalactic transients of comparable flux density.Comment: 9 pages, 4 figures, 2 tables. Accepted for publication by Astronomy
and Astrophysic
Quality of life in alopecia areata: A disease-specific questionnaire
Background Alopecia areata (AA) is an autoimmune disease affecting about 2% of the population, which has a considerable impact on quality of life (QoL). There are no disease-specific questionnaires to assess QoL in patients suffering from AA. Objective To validate a new disease-specific questionnaire for AA, named AA-QLI, and to compare the consequent Quality of Life Index (QLI) with the commonly known Dermatology Life Quality Index (DLQI) to verify if it can provide a more comprehensive tool for patients. Methods A total of 50 patients affected by AA were administered both the AA-QLI, created by us, and the well-known DLQI. With the aim to detect suitable QLI, we propose to use two multivariate analyses: a principal component analysis approach on the data collected with both questionnaires to compare their capability to measure the QoL; a structural equation modelling on our AA-QLI to identify which category of symptoms mostly affects the QoL. Results The scores of both the questionnaires are quite close, except for a few cases. Statistical analysis shows a higher specificity of the AA-QLI for evaluating QoL. Among the three areas in which AA-QLI is divided, 'Relationship' has a major impact on the QLI, followed by 'Subjective symptoms'; 'Objective signs' has a lower weight on the QLI. Conclusion AA-QLI is a good instrument to evaluate the real impact of AA on QoL. It can be helpful both for the physician and for the patient. © 2012 European Academy of Dermatology and Venereology
Short GRBs at the dawn of the gravitational wave era
We derive the luminosity function and redshift distribution of short Gamma
Ray Bursts (SGRBs) using (i) all the available observer-frame constraints (i.e.
peak flux, fluence, peak energy and duration distributions) of the large
population of Fermi SGRBs and (ii) the rest-frame properties of a complete
sample of Swift SGRBs. We show that a steep with a>2.0
is excluded if the full set of constraints is considered. We implement a Monte
Carlo Markov Chain method to derive the and functions
assuming intrinsic Ep-Liso and Ep-Eiso correlations or independent
distributions of intrinsic peak energy, luminosity and duration. To make our
results independent from assumptions on the progenitor (NS-NS binary mergers or
other channels) and from uncertainties on the star formation history, we assume
a parametric form for the redshift distribution of SGRBs. We find that a
relatively flat luminosity function with slope ~0.5 below a characteristic
break luminosity ~3 erg/s and a redshift distribution of SGRBs
peaking at z~1.5-2 satisfy all our constraints. These results hold also if no
Ep-Liso and Ep-Eiso correlations are assumed. We estimate that, within ~200 Mpc
(i.e. the design aLIGO range for the detection of GW produced by NS-NS merger
events), 0.007-0.03 SGRBs yr should be detectable as gamma-ray events.
Assuming current estimates of NS-NS merger rates and that all NS-NS mergers
lead to a SGRB event, we derive a conservative estimate of the average opening
angle of SGRBs: ~3-6 deg. Our luminosity function implies an
average luminosity L~1.5 erg/s, nearly two orders of magnitude
higher than previous findings, which greatly enhances the chance of observing
SGRB "orphan" afterglows. Efforts should go in the direction of finding and
identifying such orphan afterglows as counterparts of GW events.Comment: 13 pages, 5 figures, 2 tables. Accepted for publication in Astronomy
& Astrophysics. Figure 5 and angle ranges corrected in revised versio
FFAs and QT intervals in obese women with visceral adiposity: Effects of sustained weight loss over 1 year
We evaluated 66 obese patients grouped by waist-to-hip ratio (WHR) into group A (WHR > 0.85, n = 30) and group B (WHR ≤ 0.85, n = 36), before and after 1 yr of diet-induced weight loss compared with 25 nonobese women. Before diet, the longest values of QT intervals and the highest levels of FFA and catecholamines were in group A (P < 0.01). In obese women (both groups), the corrected QT (QTc); interval correlated with plasma FFA (P < 0.01) and catecholamine (P < 0.02) concentrations. After 1 yr of diet, at the same levels of body weight reduction, the decrement of the QTc interval (P < 0.02), FFA (P < 0.01) and catecholamine (P < 0.02) levels were significantly greater in-group A than group B. In multivariate analysis, the decline of the QTc interval after weight loss was associated with changes in plasma FFA independently of changes in WHR and plasma catecholamines. Our data suggest that the QTc interval is tightly correlated with plasma FFA levels; shortening of cardiac repolarization times in the course of long-lasting weight reduction may reduce the risk of ventricular electrical instability, especially in women with abdominal adiposity
The high-redshift gamma-ray burst GRB140515A
High-redshift gamma-ray bursts have several advantages for the study of the
distant universe, providing unique information about the structure and
properties of the galaxies in which they exploded. Spectroscopic identification
with large ground-based telescopes has improved our knowledge of the class of
such distant events. We present the multi-wavelength analysis of the high-
Swift gamma-ray burst GRB140515A (). The best estimate of the
neutral hydrogen fraction of the intergalactic medium (IGM) towards the burst
is . The spectral absorption lines detected for this event
are the weakest lines ever observed in gamma-ray burst afterglows, suggesting
that GRB140515A exploded in a very low density environment. Its circum-burst
medium is characterised by an average extinction (A) that
seems to be typical of events. The observed multi-band light curves
are explained either with a very flat injected spectrum () or with a
multi-component emission (). In the second case a long-lasting central
engine activity is needed in order to explain the late time X-ray emission. The
possible origin of GRB140515A from a Pop III (or from a Pop II stars with local
environment enriched by Pop III) massive star is unlikely.Comment: 10 pages, 8 figures, 5 tables, submitted to Astronomy & Astrophysic
How neuronal migration contributes to the morphogenesis of the CNS: insights from the zebrafish
We used transgenic zebrafish expressing GFP or YFP in subpopulations of neurons to study the migration, homing process and axon extension of groups of CNS neurons in different regions of the zebrafish brain. We found that extensive migration takes place at all levels of the CNS and gives rise to nuclei or cell populations with specific identities. Here, we describe 4 previously unknown or only partially characterized migratory events taking place in the zebrafish telencephalon and rhombic lip, using 3 different transgenic lines, and identify the phenotypes of the cells undertaking these migrations. The migration of a subgroup of mitral cell precursors from the dorsocaudal telencephalon to the olfactory bulb, visualized in the tg(tbr1:YFP) transgenic line, is coupled with morphogenetic transformation of the dorsal telencephalon. The tg(1.4dlx5a-6a:GFP) transgenic line provides a means to analyze the migration of GABAergic interneurons from the ventral to the dorsal telencephalon, thus extending the occurrence of this migration to another vertebrate. The tg(Xeom:GFP) transgenic line provides the first demonstration of the dorsoventral migration of glutamatergic septal neurons, present in mammals and now described in fish, thus reconciling the contrasting evidence of dorsal patterning genes (tbr1, eomes) expressed in a ventral cell population. Furthermore, migration studies in the tg(1.4dlx5a-6a:GFP) and tg(Xeom:GFP) lines help determine the origin of 2 important cell populations in the fish cerebellum: projection neurons and Purkinje cells. These examples reinforce the concept that migratory events contribute to the distribution of cell types with diverse identities through the CNS and that zebrafish transgenic lines represent excellent tools to study these events. Copyrigh
The Contribution of the Università degli Studi di Napoli “L'Orientale” to the 2013-2014 Eritrean-Italian Archaeological Field Season at Adulis
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