Quasi-particle random phase approximation with quasi-particle-vibration coupling: application to the Gamow-Teller response of the superfluid nucleus 120^{120}Sn

We propose a self-consistent quasi-particle random phase approximation (QRPA) plus quasi-particle-vibration coupling (QPVC) model with Skyrme interactions to describe the width and the line shape of giant resonances in open-shell nuclei, in which the effect of superfluidity should be taken into account in both the ground state and the excited states. We apply the new model to the Gamow-Teller resonance in the superfluid nucleus $^{120}$Sn, including both the isoscalar spin-triplet and the isovector spin-singlet pairing interactions. The strength distribution in $^{120}$Sn is well reproduced and the underlying microscopic mechanisms, related to QPVC and also to isoscalar pairing, are analyzed in detail.Comment: 32 pages, 11 figures, 4 table

Temperature dependence of electron-spin relaxation in a single InAs quantum dot at zero applied magnetic field

The temperature-dependent electron spin relaxation of positively charged excitons in a single InAs quantum dot (QD) was measured by time-resolved photoluminescence spectroscopy at zero applied magnetic fields. The experimental results show that the electron-spin relaxation is clearly divided into two different temperature regimes: (i) T < 50 K, spin relaxation depends on the dynamical nuclear spin polarization (DNSP) and is approximately temperature-independent, as predicted by Merkulov et al. (ii) T > about 50 K, spin relaxation speeds up with increasing temperature. A model of two LO phonon scattering process coupled with hyperfine interaction is proposed to account for the accelerated electron spin relaxation at higher temperatures.Comment: 10 pages, 4 figure

δ\delta meson effects on neutron stars in the modified quark-meson coupling model

The properties of neutron stars are investigated by including $\delta$ meson field in the Lagrangian density of modified quark-meson coupling model. The $\Sigma^-$ population with $\delta$ meson is larger than that without $\delta$ meson at the beginning, but it becomes smaller than that without $\delta$ meson as the appearance of $\Xi^-$. The $\delta$ meson has opposite effects on hadronic matter with or without hyperons: it softens the EOSes of hadronic matter with hyperons, while it stiffens the EOSes of pure nucleonic matter. Furthermore, the leptons and the hyperons have the similar influence on $\delta$ meson effects. The $\delta$ meson increases the maximum masses of neutron stars. The influence of $(\sigma^*,\phi)$ on the $\delta$ meson effects are also investigated.Comment: 10 pages, 6 figures, 4 table

Vanishing viscosity limits for the degenerate lake equations with Navier boundary conditions

The paper is concerned with the vanishing viscosity limit of the two-dimensional degenerate viscous lake equations when the Navier slip conditions are prescribed on the impermeable boundary of a simply connected bounded regular domain. When the initial vorticity is in the Lebesgue space $L^q$ with $2<q\le\infty$, we show the degenerate viscous lake equations possess a unique global solution and the solution converges to a corresponding weak solution of the inviscid lake equations. In the special case when the vorticity is in $L^\infty$, an explicit convergence rate is obtained

Splice variants of DOMINO control Drosophila circadian behavior and pacemaker neuron maintenance.

Circadian clocks control daily rhythms in behavior and physiology. In Drosophila, the small ventral lateral neurons (sLNvs) expressing PIGMENT DISPERSING FACTOR (PDF) are the master pacemaker neurons generating locomotor rhythms. Despite the importance of sLNvs and PDF in circadian behavior, little is known about factors that control sLNvs maintenance and PDF accumulation. Here, we identify the Drosophila SWI2/SNF2 protein DOMINO (DOM) as a key regulator of circadian behavior. Depletion of DOM in circadian neurons eliminates morning anticipatory activity under light dark cycle and impairs behavioral rhythmicity in constant darkness. Interestingly, the two major splice variants of DOM, DOM-A and DOM-B have distinct circadian functions. DOM-A depletion mainly leads to arrhythmic behavior, while DOM-B knockdown lengthens circadian period without affecting the circadian rhythmicity. Both DOM-A and DOM-B bind to the promoter regions of key pacemaker genes period and timeless, and regulate their protein expression. However, we identify that only DOM-A is required for the maintenance of sLNvs and transcription of pdf. Lastly, constitutive activation of PDF-receptor signaling rescued the arrhythmia and period lengthening of DOM downregulation. Taken together, our findings reveal that two splice variants of DOM play distinct roles in circadian rhythms through regulating abundance of pacemaker proteins and sLNvs maintenance

More is Better? Measurement of MPTCP based Cellular Bandwidth Aggregation in the Wild

4G/3G networks have been widely deployed around the world to provide high wireless bandwidth for mobile users. However, the achievable 3G/4G bandwidth is still much lower than their theoretic maximum. Signal strengths and available backhaul capacities may vary significantly at different locations and times, often leading to unsatisfactory performance. Bandwidth aggregation, which uses multiple interfaces concurrently for data transfer, is a readily deployable solution. Specifically, Multi-Path TCP (MPTCP) has been advocated as a promising approach for leveraging multiple source-destination paths simultaneously in the transport layer. In this paper, we investigate the efficiency of an MPTCP-based bandwidth aggregation framework based on extensive measurements. In particular, we evaluate the gain for bandwidth aggregation across up to 4 cellular operators’ networks, with respect to factors such as time, user location, data size, aggregation proxy location and congestion control algorithm. Our measurement studies reveal that (1) bandwidth aggregation in general improves the cellular network bandwidth experienced by mobile users, but the performance gain is significant only for bandwidth-intensive delay-tolerant flows; (2) the effectiveness of aggregation depends on many network factors, including QoS of individual cellular interfaces and the location of aggregation proxy; (3) contextual factors, including the time of day and the mobility of a user, also affect the aggregation performance.postprin

Theory of I-V Characteristics of Magnetic Josephson Junctions

We analyze the electrical characteristics of a circuit consisting of a free thin-film magnetic layer and source and drain electrodes that have opposite magnetization orientations along the free magnet's two hard directions. We find that when the circuit's current exceeds a critical value there is a sudden resistance increase which can be large in relative terms if the currents to source or drain are strongly spin polarized and the free magnet is thin. This behavior can be partly understood in terms of a close analogy between the magnetic circuit and a Josephson junction