X Ray Detection of GJ 581 and simultaneous UV Observations

Context. GJ 581, an M3 dwarf, hosts a rich system of exo-planets, some of which are potentially within or at the edge of the Habitable Zone. Nevertheless the system habitability might be reduced by large and sterilizing high energy emission flares, if these are frequent. Aims. The GJ 581 radiation environment was studied with simultaneous X-ray and UV observations, performed with the XRT and UVOT instruments, respectively, on board of the SWIFT satellite. Methods. X-ray and UV data were analysed with the distributed standard tools. Results. GJ 581 was detected for the first time in the 0.2-10 keV range, with an intensity of (8+-2)x10^{-4} cts/s and a signal-to-noise ratio of 3.6. If black-body or APEC spectra are assumed then the source X-ray flux is found to be between 1.8 and 3.3x10^{-14}erg cm^{-2}s^{-1} and log10(L_{X}) between 25.914 and 26.176. Despite hints of X-ray variability, better statistics will be needed to establish robust evidence for that. The UV measurements, obtained during 13 pointings, are also reported. A combination of these Swift X-ray and Hubble Space Telescope UV measurements (with Lyman-alpha) indicate a low X-ray to UV luminosity ratio of ~4%. Conclusions. Simultaneous X-ray and UV observations of GJ 581 are reported. These constitute an experimental view of the system radiation environment, which will be a useful input for the habitability studies of the GJ 581 planetary system.Comment: 5 Pages, 2 figures. Accepted for publication in A&

T-Dualities and Doubled Geometry of the Principal Chiral Model

The Principal Chiral Model (PCM) defined on the group manifold of SU(2) is here investigated with the aim of getting a further deepening of its relation with Generalized and Doubled Geometry. A one-parameter family of equivalent Hamiltonian descriptions is introduced, and cast into the form of Born geometries. Then O(3,3) duality transformations of the target phase space are performed and we show that the resulting dual models are defined on the group SB(2,C) which is the Poisson-Lie dual of SU(2) in the Iwasawa decomposition of the Drinfel'd double SL(2, C). Moreover, starting from the Lagrangian approach, a new kind of duality is found between the SU(2) PCM and the natural one defined on SB(2,C) which is not an isometry of the target phase space. A parent action with doubled degrees of freedom and configuration space SL(2, C) is then defined that reduces to either one of the dually related models, once suitable constraints are implemented.Comment: 41 pages, revised version published in JHE

Doubling, T-Duality and Generalized Geometry: a Simple Model

A simple mechanical system, the three-dimensional isotropic rigid rotator, is here investigated as a 0+1 field theory, aiming at further investigating the relation between Generalized/Double Geometry on the one hand and Doubled World-Sheet Formalism/Double Field Theory, on the other hand. The model is defined over the group manifold of SU(2) and a dual model is introduced having the Poisson-Lie dual of SU(2) as configuration space. A generalized action with configuration space SL(2,C), i.e. the Drinfel'd double of the group SU(2), is then defined: it reduces to the original action of the rotator or to its dual, once constraints are implemented. The new action contains twice as many variables as the original. Moreover, its geometric structures can be understood in terms of Generalized Geometry. keywords: Generalized Geometry, Double Field Theory, T-Duality, Poisson-Lie symmetry.Comment: 37 pages. Revised version to appear in JHE

A new microsimulation model for the evaluation of traffic safety performances

Some papers have been recently presented (Cunto and Saccomanno 2007, Cunto and Saccomanno 2008, Saccomanno et al. 2008) on the potential of traffic microsimulation for the analysis of road safety. In particular, studies have confirmed that the reproduction by simulation of user behaviour under different flow and geometry conditions, can identify a potential incident hazard and allow to take appropriate countermeasures at specific points of the road network. The objective of this paper is to assess the validity of this approach; for this reason a microsimulation model and an automatic video detection system have been developed. The microscopic model allows the estimation of road safety performance through a series of indicators (Deceleration Rate to Avoid Crash, Time to Collision, Proportion of Stopping Distance), representing interactions in real time, between different pairs of vehicles belonging to the traffic stream. When these indicators take a certain critical value, a possible accident scenario is identified. The microscopic simulation model is used combined with a new video image traffic detection algorithm to calculate vehicle trajectories. Microscopic traffic flow parameters obtained by video detection are used to calibrate the microsimulation model, and the safety performance indicators obtained by the real vehicles trajectories can be compared with simulated scenarios where safety performance indicators are obtained on the simulated trajectories. Results indicate that the methodology can be useful in the estimation of safety performance indicators and in evaluating traffic control measures

Hospitalization rates for intussusception in children aged 0–59 months from 2009 to 2014 in Italy

The real cause of intussusception is not fully understood and a variety of conditions have been associated with it (Meckel diverticulum, polyps, duplication cysts, parasites, Henoch-Schönlein purpura, cystic fibrosis, hemolytic-uremic syndrome and infectious gastroenteritis). Furthermore few European countries, following WHO recommendation to monitor baseline incidence of intussusception before implementation of immunization program for rotavirus, used intussusception rate as a baseline value to compare the same figures in the period before and after introduction of vaccination. In this study, data of intussusception hospitalizations occurred among Italian children aged 0 through 59 months from 2009 to 2014 were analyzed. A total amount of 3,088 children were included, accounting for a hospitalization rate of 20.2 per 100,000. Overall, the hospitalization rate for intussusception had a slight increase in trend from 2009 to 2014 (18%). In particular children 0–11 months had a hospitalization rate higher than 12–59 months with an aggregate value of 36 Vs. 16 per 100,000 respectively. Among all children hospitalized for intussusception a total of 239 (7.7%) had also a previous or concomitant hospitalization for gastroenteritis. This study demonstrates that Italian hospitalizations for intussusception are increasing by time and the role played by different risk factors, including acute gastroenteritis, have to be investigated in the future. These data could be useful to monitor intussusception hospitalization in the perspective of anti-rotavirus vaccination introduction in Italy

Cost analysis of the first two year of universal mass vaccination against rotavirus in Sicily

Background Rotavirus vaccination (RV) is recognized by international health authority as the best strategy to prevent rotavirus gastroenteritis (RVGE) in children. Costs of RVGE were estimated in several studies and were classified into direct and indirect costs, that should be further divided into Health care and social perspective. This study aims to evaluate RVGE hospitalization costs in Sicily, before and after universal mass RV (UMRV) introduction. Methods Cases of RVGE were defined as all hospitalizations with an ICD-9-CM diagnosis code of 008.61 on any diagnosis position among children aged 0 to 59 months. Data were obtained from Hospital discharge records (HDR) of the Health Regional Office from 2009 to 2014. Direct and indirect costs of RVGE hospitalization for health care and social perspective were calculated on data reported in the REVEAL study. RV costs was extrapolated from a budget impact analysis published in 2013 by Vitale et al. Results In Sicily, during the pre-vaccination era (2009-2012) were reported 963 RVGE hospitalizations per year with a mean HDR cost of 1,521E (1,465,000E per year) , against 511 RVGE cases per year (mean HDR cost of 1,321E; 675,000E per year) after UMRV introduction (direct hospitalization Health care costs). Moreover, direct and indirect hospitalization costs for social perspective was estimated 1.5 times bigger than direct hospitalization health care cost (pre-vaccination era 2,255,000E per year, post-vaccination era 1,020,000E per year). Finally, cost of RV vaccine in Sicily in 2013 and 2014 was 1,300,000E per year (mean vaccination coverage 37%). In Sicily after RV introduction, every year was estimated a 46% reduction of RVGE hospitalizations and a 700,000E benefit for Regional fund. Conclusions Despite low vaccination rate and even though the inability to evaluate the impact of RV vaccination on primary care and emergency access for RVGE, our study demonstrated the high cost-effectiveness of UMRV on hospitalization rate and costs in Sicily