Magnetic relaxation of type II superconductors in a mixed state of entrapped and shielded flux

The magnetic relaxation has been investigated in type II superconductors when the initial magnetic state is realized with entrapped and shielded flux (ESF) contemporarily. This flux state is produced by an inversion in the magnetic field ramp rate due to for example a magnetic field overshoot. The investigation has been faced both numerically and by measuring the magnetic relaxation in BSCCO tapes. Numerical computations have been performed in the case of an infinite thick strip and of an infinite slab, showing a quickly relaxing magnetization in the first seconds. As verified experimentally, the effects of the overshoot cannot be neglected simply by cutting the first 10-100 seconds in the magnetic relaxation. On the other hand, at very long times, the magnetic states relax toward those corresponding to field profiles with only shielded flux or only entrapped flux, depending on the amplitude of the field change with respect to the full penetration field of the considered superconducting samples. In addition, we have performed numerical simulations in order to reproduce the relaxation curves measured on the BSCCO(2223) tapes; this allowed us to interpret correctly also the first seconds of the $M(t)$ curves.Comment: 9 pages, 12 figures submit to PR

Harmonics of the AC susceptibility as probes to differentiate the various creep models

We measured the temperature dependence of the 1st and the 3rd harmonics of the AC magnetic susceptibility on some type II superconducting samples at different AC field amplitudes, hAC. In order to interpret the measurements, we computed the harmonics of the AC susceptibility as function of the temperature T, by integrating the non-linear diffusion equation for the magnetic field with different creep models, namely the vortex glass-collective creep (single-vortex, small bundle and large bundle) and Kim-Anderson model. We also computed them by using a non-linear phenomenological I-V characteristics, including a power law dependence of the pinning potential on hAC. Our experimental results were compared with the numerically computed ones, by the analysis of the Cole-Cole plots. This method results more sensitive than the separate component analysis, giving the possibility to obtain detailed information about the contribution of the flux dynamic regimes in the magnetic response of the analysed samples.Comment: 9 pages, 6 figures, submitted to Physica

Binge-Eating Symptoms, emotional-behavioral problems and gender differences among adolescents: A brief report

We investigated relationships between binge-eating symptoms and emotional-behavioral problems in 382 community-adolescents (aged 13-18 years, M = 15, SD = 1; 61% girls), analyzing gender differences. Few studies have investigated binge eating in community-adolescents and none have explored gender differences in Italy. Participants completed the Binge Eating Scale (BES) and the Youth Self Report (YSR 11/18), which measures internalizing, externalizing and other problems (e.g. binge-drinking, substance abuse). 6% of adolescents (99% girls) were at-risk of binge-eating symptoms. In both gender, binge-eating symptoms were correlated with internalizing and other problems (all p < .001), but unexpectedly they were correlated with externalizing problems only in girls. The set of internalizing, externalizing and other problems predicted 23% of variance in BES among girls; only other problems predicted 12% of variance in BES among boys. Results identified gender-specific and non-specific risk factors for binge eating in Italian community-adolescents, that should be further investigated

Attachment and alexithymia predict emotional–behavioural problems of institutionalized, late-adopted and community adolescents: An explorative multi-informant mixed-method study

Objective: Compared to community adolescents (COM), adolescents placed in residential care (RC) or late adopted (LA) appear to show more emotional–behavioural problems. They also appear vulnerable in variables linked to emotional–behavioural problems, such as insecure–disorganized attachment and alexithymia. This study employs a mixed-method multi-informant approach to (1) compare adolescents placed in RC, LA and COM in emotional–behavioural problems, attachment and alexithymia and (2) investigate relationships and interplay of attachment and alexithymia concerning emotional–behavioural problems in these three groups. Method: Participants were 174 adolescents (50 RC, 33 LA and 91 COM; Mage = 15, 53% boys and 47% girls). Adolescents' internalizing and externalizing problems were assessed through both caregiver-reported and self-reported questionnaires, while attachment and alexithymia were assessed with a mixed method, using interviews and self-report questionnaires. Results: The results showed RC adolescents as more vulnerable in all variables, while LA and COM did not differ. Accounting for the group, attachment and alexithymia cumulatively predicted 25–43% of internalizing problems, and 19–43% of externalizing problems depending on the method of assessment or problems' informant (all p < 0.01). Alexithymia was both an independent predictor and interacted with preoccupied attachment in predicting internalizing problems, while no predictors were isolated for externalizing ones, and the group never indicate an effect on problems' rates. Conclusions: The authors discuss the utility to maintain a research focus on attachment and alexithymia, also suggesting future directions of research. A need to determine potential distortions of results because of problems' informant and method of assessment is also highlighted

Adaptive statistical pattern classifiers for remotely sensed data

A technique for the adaptive estimation of nonstationary statistics necessary for Bayesian classification is developed. The basic approach to the adaptive estimation procedure consists of two steps: (1) an optimal stochastic approximation of the parameters of interest and (2) a projection of the parameters in time or position. A divergence criterion is developed to monitor algorithm performance. Comparative results of adaptive and nonadaptive classifier tests are presented for simulated four dimensional spectral scan data

Timelike and spacelike hadron form factors, Fock state components and light-front dynamics

A unified description of spacelike and timelike hadron form factors within a light-front model was successfully applied to the pion. The model is extended to the nucleon to study the role of $q \bar q$ pair production and of nonvalence components in the nucleon form factors. Preliminary results in the spacelike range $0 \le Q^2 \le 10 ~ (GeV/c)^2$ are presented.Comment: 4 pages, espcrc1.sty. proceedings of FB XVIII (August 2006, Brazil), to be published in Nucl. Phys.

Electromagnetic Hadron Form Factors and Higher Fock Components

Investigation of the spacelike and timelike electromagnetic form factors of hadrons, within a relativistic microscopical model characterized by a small set of hypothesis, could shed light on the components of hadron states beyond the valence one. Our relativistic approach has been successfully applied first to the pion and then the extension to the nucleon has been undertaken. The pion case is shortly reviewed as an illustrative example for introducing the main ingredients of our approach, and preliminary results for the nucleon in the spacelike range $-10 (GeV/c)^2\le q^2 \le 0$ are evaluated.Comment: 8 pages, 6 figs, espcrc1.sty included. Proceedings of Fifth International Conference on Perspectives In Hadronic Physics, ICTP, May 22-26, 200