Nonequilibrium Josephson effect in mesoscopic ballistic multiterminal SNS junctions

We present a detailed study of nonequilibrium Josephson currents and conductance in ballistic multiterminal SNS-devices. Nonequilibrium is created by means of quasiparticle injection from a normal reservoir connected to the normal part of the junction. By applying a voltage at the normal reservoir the Josephson current can be suppressed or the direction of the current can be reversed. For a junction longer than the thermal length, $L\gg\xi_T$, the nonequilibrium current increases linearly with applied voltage, saturating at a value equal to the equilibrium current of a short junction. The conductance exhibits a finite bias anomaly around $eV \sim \hbar v_F/L$. For symmetric injection, the conductance oscillates $2\pi$-periodically with the phase difference $\phi$ between the superconductors, with position of the minimum ($\phi=0$ or $\pi$) dependent on applied voltage and temperature. For asymmetric injection, both the nonequilibrium Josephson current and the conductance becomes $\pi$-periodic in phase difference. Inclusion of barriers at the NS-interfaces gives rise to a resonant behavior of the total Josephson current with respect to junction length with a period $\sim \lambda_F$. Both three and four terminal junctions are studied.Comment: 21 pages, 19 figures, submitted to Phys. Rev.

Bullying and Victimization Among Boys and Girls in Middle School: The Influence of Perceived Family and School Contexts

The present study examines the mechanisms by which students\u27 perceptions of family and school experiences moderate the association between their emotionality and their habitual involvement in bullying and victimization. The authors hypothesize that students with internalizing and/or externalizing difficulties are less likely to be categorized as bullies and/or victims if they report coming from more cohesive and adaptable families and attending schools characterized by higher adult monitoring, lower levels of aggression and disorder, and higher levels of school bonding. Home and school environments in which these characteristics are less evident to students were expected to exacerbate the likelihood of being bullies and/or victims. Middle school youth (N = 2,506) and their teachers completed surveys assessing emotionality, peer relationships, academic performance, and home and school contexts. Using multinomial logistic regression, the authors found that perceived climates low in student misconduct increase the likelihood that internalizing difficulties predicted classification as victims. Increased student-reported adult monitoring decreased the likelihood for students with externalizing problems to be characterized as bullies, particularly for girls. These findings have implications for the development of school-based intervention programming