Multifractal metal in a disordered Josephson Junction Array

We report the results of the numerical study of the non-dissipative quantum Josephson junction chain with the focus on the statistics of many-body wave functions and local energy spectra. The disorder in this chain is due to the random offset charges. This chain is one of the simplest physical systems to study many-body localization. We show that the system may exhibit three distinct regimes: insulating, characterized by the full localization of many-body wavefunctions, fully delocalized (metallic) one characterized by the wavefunctions that take all the available phase volume and the intermediate regime in which the volume taken by the wavefunction scales as a non-trivial power of the full Hilbert space volume. In the intermediate, non-ergodic regime the Thouless conductance (generalized to many-body problem) does not change as a function of the chain length indicating a failure of the conventional single-parameter scaling theory of localization transition. The local spectra in this regime display the fractal structure in the energy space which is related with the fractal structure of wave functions in the Hilbert space. A simple theory of fractality of local spectra is proposed and a new scaling relationship between fractal dimensions in the Hilbert and energy space is suggested and numerically tested.Comment: 11 page

A magnetic reconnection model for explaining the multi-wavelength emission of the microquasars Cyg X-1 and Cyg X-3

Recent studies have indicated that cosmic ray acceleration by a first-order Fermi process in magnetic reconnection current sheets can be efficient enough in the surrounds of compact sources. In this work, we discuss this acceleration mechanism operating in the core region of galactic black hole binaries (or microquasars) and show the conditions under which this can be more efficient than shock acceleration. In addition, we compare the corresponding acceleration rate with the relevant radiative loss rates obtaining the possible energy cut-off of the accelerated particles and also compute the expected spectral energy distribution (SED) for two sources of this class, namely Cygnus X-1 and Cygnus X-3, considering both leptonic and hadronic processes. The derived SEDs are comparable to the observed ones in the low and high energy ranges. Our results suggest that hadronic non-thermal emission due to photo-meson production may produce the very high energy gamma-rays in these microquasars.Comment: 17 pages and 7 figures. Accepted for publication in the Monthly Notices of the Royal Astronomical Society (MNRAS

Ultra-High-Energy Cosmic Ray Acceleration by Magnetic Reconnection in Newborn Accretion Induced Collapse Pulsars

We here investigate the possibility that the ultra-high energy cosmic ray (UHECR) events observed above the GZK limit are mostly protons accelerated in reconnection sites just above the magnetosphere of newborn millisecond pulsars which are originated by accretion induced collapse (AIC). We show that AIC-pulsars with surface magnetic fields $10^{12} G < B_{\star} \lesssim 10^{15}$ G and spin periods $1 ms \lesssim P_{\star} < 60 ms$, are able to accelerate particles to energies $\geq 10^{20}$ eV. Because the expected rate of AIC sources in our Galaxy is very small (\sim 10^{-5} yr^{-1}), the corresponding contribution to the flux of UHECRs is neglegible, and the total flux is given by the integrated contribution from AIC sources produced by the distribution of galaxies located within the distance which is unaffected by the GZK cutoff ($\sim 50$ Mpc). We find that the reconnection efficiency factor needs to be $\xi \gtrsim 0.1$ in order to reproduce the observed flux of UHECRs.Comment: Latex file, 16 pages, 2 figures, replaced with revised version accepted for publication in the ApJ letter

Upper mantle compressional velocity structure beneath the West Mediterranean Basin

P waveforms of regional crustal earthquakes have been modeled to obtain an upper mantle compressional velocity model for the West Mediterranean Basin. Data come from long-period stations of the World-Wide Standardized Seismograph Network and broadband stations located in the Iberian Peninsula. Synthetic waveforms have first been computed for published velocity models corresponding to different tectonic provinces and obtained with analogous techniques. A model that strongly improves the fits to the data is then derived. The proposed model is characterized by a 100-km-thick lid overlaying a not very pronounced low-velocity zone and a 3% discontinuity at 368 km where an increase of the velocity gradient also occurs. These features could be explained either as a deflection of the olivine-to-spinel phase transition, regionally detected at about 395 km, resulting from the lower temperature produced by the subduction of the African plate, or as being due to the presence below 300 km depth of a layer of silicate melt, producing a strong reflection from its bottom, and a more usual depth for the olivine-spinel transition. In both cases the occurrence of relatively low velocities beneath 300 km is interpreted as being caused by the presence of melt associated with the northward dipping subduction of the African plate

Modeling the spectrum of gravitational waves in the primordial Universe

Recent observations from type Ia Supernovae and from cosmic microwave background (CMB) anisotropies have revealed that most of the matter of the Universe interacts in a repulsive manner, composing the so-called dark energy constituent of the Universe. The analysis of cosmic gravitational waves (GW) represents, besides the CMB temperature and polarization anisotropies, an additional approach in the determination of parameters that may constrain the dark energy models and their consistence. In recent work, a generalized Chaplygin gas model was considered in a flat universe and the corresponding spectrum of gravitational waves was obtained. The present work adds a massless gas component to that model and the new spectrum is compared to the previous one. The Chaplygin gas is also used to simulate a $\Lambda$-CDM model by means of a particular combination of parameters so that the Chaplygin gas and the $\Lambda$-CDM models can be easily distinguished in the theoretical scenarios here established. The lack of direct observational data is partialy solved when the signature of the GW on the CMB spectra is determined.Comment: Proc. of the Conference on Magnetic Fields in the Universe: from laboratories and stars to primordial structures, AIP(NY), eds. E. M. de Gouveia Dal Pino, G. Lugones & A. Lazarian (2005), in press. (8 pages, 11 figures

Blending process assessment and employees competencies assessment in very small entities

The ISO/IEC 29110 series aims to provide Very Small Entities (VSEs) with a set of standards based on subsets of existing standards. Process capability determination does not seem suitable for a VSE in terms of return on investment. Our approach proposes to move the viewpoint away from process and to the human resources. We propose a blended assessment model using the ISO/IEC 15504 for the level 1, but based on competency assessment for higher capability levels

An Automated Method for Mapping Independent Spatial b Values

We present an automated method for mapping the b values. The algorithm is very simple and presents three advantages: (a) it does not requires any tuning of the parameters like, for instance, a fixed cell size or a maximum radius of the cell; (b) it implies a more appropriate use of the catalog, by using almost all the events in the catalog used (with a tolerance of 1%) with no overlap; (c) it implies the full independence of the b values, thus allowing the statistical comparison of the results using standard tests. Although the resulting b values are comparable with those obtained by applying the other methods of common use in seismology, these latter (a) leave out many earthquakes from the analysis, with loose of useful information, (b) produce diffuse cells overlapping aiming at reaching many cells of the grid in order to get the correct number of events in each cell, and (c) results in correlated b values, which do not allow the test of significance for the differences in the b values. Finally, due to the independence from any ad hoc a-priori choice, our method is suitable for automatic and operator-free procedures.Plain Language Summary The methods usually used in seismology for mapping the b value require the tuning of some parameters depending on the analyzed catalog. Here we propose a method that only implies the choice of the minimum number of earthquakes needed to obtain reliable b value estimates, which does not depend on the specific cases. Due to the mutual complete independence of the resulting b values, the proposed method allows the use of standard statistical tests to compare the results

Post-Traumatic Outcomes among Survivors of the Earthquake in Central Italy of August 24, 2016. A Study on PTSD Risk and Vulnerability Factors

Central Italy suffered from the earthquake of 2016 resulting in great damage to the community. The purpose of the present study was to determine the long-term traumatic outcomes among the population. A preliminary study aimed at obtaining the Italian translation of the first 16 item of HTQ IV part [1] which was administered, 20&nbsp;months after the disaster, at 281 survivors. In backward stepwise logistic regressions models, we estimated among the respondent’s characteristics and event-related variables the best predictors of Post-Traumatic Stress Disorder (PTSD). A Confirmatory Factor Analysis (CFA) revealed a HTQ five-factors solution as best model, with satisfactory indexes of fit. HTQ held a positive correlation with both the SQD-P (r =.65, p &lt;.05) and SQD-D subscales (r =.47, p &lt;.05). ROC analysis suggested an area of.951 (95% CI =.917–.985) for the PTSD prediction. Basing on sensibility (.963) and specificity (.189), the best cut-off of 2.0 allowed discriminating for PTSD positive cases. After 20&nbsp;months of the earthquake, the estimate prevalence of PTSD among the survivors is of 21.71% with a consistent and graded association between exposure variables and vulnerability factors (gender, age, exposure to death and home damage) and PTSD symptoms