Time delay between the optical and X-ray outbursts in the high mass X-ray transient A0535+26/HDE245770

The optical behaviour of the Be star in the high mass X-ray transient A0535+26/HDE245770 shows that at the periastron typically there is an enhancement in the luminosity of order 0.02 to few tenths mag, and the X-ray outburst happens about 8 days after the periastron. We construct a quantitative model of this event, basing on the a nonstationary accretion disk behavior, connected with a high ellipticity of the orbital motion. The ephemeris used in this paper -- JD$_{\rm opt-outb}$ = JD$_0$(2,444,944) $\pm$ n(111.0 $\pm$ 0.4) days are derived from the orbital period of the system P$_{\rm orb} = 111.0 \pm 0.4$ days, determined by Priedhorsky & Terrell (1983), and from the optical flare of December 5, 1981 (Giovannelli et al., 1985) (here after 811205-E; E stands for the Event occurred at that date) that triggered the subsequent X-ray outburst of December 13, 1981 (Nagase et al., 1982) (here after 811213-E). We explain the observed time delay between the peaks of the optical and X-ray outbursts in this system by the time of radial motion of the matter in the accretion disk, after an increase of the mass flux in the vicinity of a periastral point in the binary. This time is determined by the turbulent viscosity, with the parameter $\alpha=0.1-0.3$. The increase of the mass flux is a sort of flush that reaches the external part of the accretion disk around the neutron star, producing an enhancement in the optical luminosity. The consequent X-ray flare happens when the matter reaches the hot central parts of the accretion disk, and the neutron star surface.Comment: 30 pages, 15 figures, with correction in abstrac

Characterization of the Intra-Unit-Cell magnetic order in Bi2Sr2CaCu2O8+d

As in YBa2Cu3O6+x and HgBa2CuO8+d, the pseudo-gap state in Bi2Sr2CaCu2O8+d is characterized by the existence of an intra-unit-cell magnetic order revealed by polarized neutron scattering technique. We report here a supplementary set of polarized neutron scattering measurements for which the direction of the magnetic moment is determined and the magnetic intensity is calibrated in absolute units. The new data allow a close comparison between bilayer systems YBa2Cu3O6+x and Bi2Sr2CaCu2O8+d and rise important questions concerning the range of the magnetic correlations and the role of disorder around optimal doping.Comment: 12 pages, 8 figures, submitted to physical review

Stellar turbulent convection: the multiscale nature of the solar magnetic signature

The multiscale dynamics associated with turbulent convection present in physical systems governed by very high Rayleigh numbers still remains a vividly disputed topic in the community of astrophysicists, and in general, among physicists dealing with heat transport by convection. The Sun is a very close star for which detailed observations and estimations of physical properties on the surface, connected to the processes of the underlying convection zone, are possible. This makes the Sun a unique natural laboratory in which to investigate turbulent convection in the hard turbulence regime, a regime typical of systems characterized by high values of the Rayleigh number. In particular, it is possible to study the geometry of convection using the photospheric magnetic voids (or simply voids), the quasi-polygonal quiet regions nearly devoid of magnetic elements, which cover the whole solar surface and which form the solar magnetic network. This work presents the most extensive statistics, both in the spatial scales studied (1-80 Mm) and in the temporal duration (SC 23 and SC 24), to investigate the multiscale nature of solar magnetic patterns associated with the turbulent convection of our star. We show that the size distribution of the voids, in the 1-80 Mm range, for the 317, 870 voids found in the 692 analyzed magnetograms, is basically described by an exponential function

Recalling an unfair experience reduces adolescents’ dishonest behavioral intentions: The mediating role of justice sensitivity

This is the author accepted manuscript. The final version is available from Springer Verlag via the DOI in this record.Injustice experiences are likely to have a strong impact on—adolescents' life. However, individuals differ in how they perceive and respond to injustice depending on their justice sensitivity. Whereas several studies analyzed the relationships between justice sensitivity and antisocial behaviors in adult samples, little is known about this relationship among adolescents. The aim of the present experimental study is to expand knowledge on the antecedents and effects of justice sensitivity from the Victim (i.e., JS-Victim) and Others (i.e., JS-Observer, Perpetrator, and Beneficiary) perspective, particularly with regard to its relationship to willingness to act in dishonest behavioral intentions (e.g., stealing money or objects from classmates, teachers, or strangers). The study involved 369 Italian students (52% males; Mage = 16.64, SD = 1.78). We examined the role of justice sensitivity in the relationship between the recall of unfair, fair, or neutral episodes, and the consequent willingness to perform dishonest behaviors. Results demonstrate that recalling unfair (vs. fair or neutral) episodes leads to an increase in JS-Others, which in turn decreased willingness to behave dishonestly. Conversely, JS-Victim did not mediate the relationship between the recall of unfair episodes and intentions to behave dishonestly. The present findings suggest that during adolescence JS-Others might act as a protective factor against dishonest behaviors.This study was made possible due a FIRB 2012 grant from the Italian Ministry of Education, University and Research (MIUR; Grant Number RBFR128CR6)

Constraints of T conformation of carp azide hemoglobin on Fe site structure

AbstractThe iron site structure modifications induced by the transition from the quaternary R to T structure in ferric carp azide hemoglobin have been detected from analysis of multiple scattering resonances in the XANES (X-ray absorption near edge structure) spectra. High signal-to-noise XANES spectra measured at the Frascati ‘wiggler’ synchrotron radiation facility reveal that the forces on the Fe active site, due to the transition from the R to T quaternary conformation, only induce the tilting of the porphyrin plane and probably also of the proximal histidine. The variation of the Fe-N mean distance is not detected by XANES spectroscopy and therefore it is less than 0.01 Å

Determining the optimal piecewise constant approximation for the nonhomogeneous Poisson process rate of Emergency Department patient arrivals

Modeling the arrival process to an Emergency Department (ED) is the first step of all studies dealing with the patient flow within the ED. Many of them focus on the increasing phenomenon of ED overcrowding, which is afflicting hospitals all over the world. Since Discrete Event Simulation models are often adopted to assess solutions for reducing the impact of this problem, proper nonstationary processes are taken into account to reproduce time–dependent arrivals. Accordingly, an accurate estimation of the unknown arrival rate is required to guarantee the reliability of results. In this work, an integer nonlinear black–box optimization problem is solved to determine the best piecewise constant approximation of the time-varying arrival rate function, by finding the optimal partition of the 24 h into a suitable number of not equally spaced intervals. The black-box constraints of the optimization problem make the feasible solutions satisfy proper statistical hypotheses; these ensure the validity of the nonhomogeneous Poisson assumption about the arrival process, commonly adopted in the literature, and prevent mixing overdispersed data for model estimation. The cost function of the optimization problem includes a fit error term for the solution accuracy and a penalty term to select an adequate degree of regularity of the optimal solution. To show the effectiveness of this methodology, real data from one of the largest Italian hospital EDs are used