Remote Charging and Degradation Suppression for the Quantum Battery

The quantum battery (QB) makes use of quantum effects to store and supply energy, which may outperform its classical counterpart. However, there are two challenges in this field. One is that the environment-induced decoherence causes the energy loss and aging of the QB, the other is that the decreasing of the charger-QB coupling strength with increasing their distance makes the charging of the QB become inefficient. Here, we propose a QB scheme to realize a remote charging via coupling the QB and the charger to a rectangular hollow metal waveguide. It is found that an ideal charging is realized as long as two bound states are formed in the energy spectrum of the total system consisting of the QB, the charger, and the electromagnetic environment in the waveguide. Using the constructive role of the decoherence, our QB is immune to the aging. Additionally, without resorting to the direct charger-QB interaction, our scheme works in a way of long-range and wireless-like charging. Effectively overcoming the two challenges, our result supplies an insightful guideline to the practical realization of the QB by reservoir engineering

Efectos agudos de la intervención musical autoseleccionada en la recuperación de las funciones autónomas y la ansiedad después de la intensidad submáxima del ciclismo a corto plazo

Antecedentes: la intervención musical se considera una modalidad óptima para mejorar la motivación del ejercicio, el rendimiento del ejercicio y la capacidad de resistencia. El objetivo de este estudio es investigar los efectos agudos de la intervención musical autoseleccionada sobre la frecuencia cardíaca (FC) posterior al ejercicio, la variabilidad de la FC (VFC) y la ansiedad después de una intensidad submáxima del ejercicio en bicicleta. Métodos: Cincuenta y dos adultos sanos (hombres: n = 24, edad: 20.6 ± 2 años; mujeres: n = 28, 21.8 ± 2.1 años) participaron voluntariamente en este estudio. Se utilizó un diseño equilibrado para examinar la intensidad submáxima del ejercicio de ciclismo con ensayos musicales no musicales o autoseleccionados con al menos 48 horas de diferencia. Los participantes primero visitan el laboratorio para determinar la música individual seleccionada por ellos mismos y completar una prueba de ejercicio incremental hasta que la respuesta de FC investigue al 80% de la reserva de frecuencia cardíaca (HRreserve). El 80% HRreserve se utilizó para controlar la intensidad del ejercicio durante un ejercicio de ciclismo estacionario de 10 minutos. Al comienzo del experimento, los participantes realizaron un ejercicio de calentamiento en bicicleta de 5 minutos con ritmo propio. Posteriormente, los participantes descansaron sentados durante 5 minutos y luego realizaron 10 minutos de ejercicio en bicicleta con una intensidad de reserva de HR del 80%. Después del ejercicio de ciclismo, se midió la recuperación de la FC de 5 minutos (HRR) y la HRV de 10 minutos en una posición sentada durante 15 minutos. Se utilizó una escala de masa de ansiedad situacional (STAI-S) inmediatamente después del ejercicio de ciclismo. La intervención musical se aplicó durante 15 minutos después de la recuperación del ejercicio. Resultados: El HR de ejercicio y el HRV posterior al ejercicio no mostraron diferencias significativas entre el ensayo musical autoseleccionado y el ensayo no musical en ambos grupos. En la prueba musical autoseleccionada, la HRR fue significativamente más rápida después de la prueba musical autoseleccionada que la de la prueba no musical en mujeres. Además, las puntuaciones de STAI-S fueron significativamente más bajas en la prueba musical autoseleccionada que en la prueba no musical en ambos grupos. Conclusión: la intervención musical autoseleccionada puede mejorar la HRR en mujeres sanas. Se justifica la implementación de una intervención musical autoseleccionada después de la intensidad submáxima del ejercicio de ciclismo estacionario para reducir la ansiedad posterior al ejercicio en hombres y mujeres.Background: Music intervention is considered as an optimal modality to improve exercise motivation, exercise performance, and endurance capacity. The aim of this study is to investigate the acute effects of self-selected music intervention on post-exercise heart rate (HR), HR variability (HRV) and anxiety after a submaximal intensity of cycling exercise. Methods: Fifty-two healthy adults (males: n= 24, age: 20.6 ± 2 yrs; female: n= 28, 21.8 ± 2.1 yrs) were voluntarily participated this study. A counter-balanced design was used to examine submaximal intensity of cycling exercise with non-music or self-selected music trials at least 48 hours apart. Participants first visit the laboratory to determine individual self-selected music and to complete an incremental exercise test until HR response researched to 80% of heart rate reserve (HRreserve). The 80% HRreserve was used to control the exercise intensity during a subsequent 10-minute stationary cycling exercise. At the beginning of experiment, the participants performed a 5-min cycling warm-up exercise with self-pace. Afterwards, the participants rested in a sitting position for 5-min and then performed 10-min cycling exercise with intensity of 80% HRreserve. After the cycling exercise, 5-min HR recovery (HRR) and 10-min HRV was measured in a sitting position for 15-min. A situational anxiety mass scale (STAI-S) was used immediately after the cycling exercise. Music intervention was applied during 15-min post-exercise recovery. Results: The exercise HR and post-exercise HRV showed no significant differences between self-selected music trial and non-music trial in both groups. In self-selected music trial, HRR was significantly faster after the self-selected music trial than that of non-music trial in female. In addition, the STAI-S scores were significantly lower in the self-selected music trial than that of non-music trial in both groups. Conclusion: Self-selected music intervention can improve HRR in healthy female. Consideration to implement a self-selected music intervention after submaximal intensity of stationary cycling exercise to reduce post-exercise anxiety in male and female is warrant

Ultra-strong Adhesion of Graphene Membranes

As mechanical structures enter the nanoscale regime, the influence of van der Waals forces increases. Graphene is attractive for nanomechanical systems because its Young's modulus and strength are both intrinsically high, but the mechanical behavior of graphene is also strongly influenced by the van der Waals force. For example, this force clamps graphene samples to substrates, and also holds together the individual graphene sheets in multilayer samples. Here we use a pressurized blister test to directly measure the adhesion energy of graphene sheets with a silicon oxide substrate. We find an adhesion energy of 0.45 \pm 0.02 J/m2 for monolayer graphene and 0.31 \pm 0.03 J/m2 for samples containing 2-5 graphene sheets. These values are larger than the adhesion energies measured in typical micromechanical structures and are comparable to solid/liquid adhesion energies. We attribute this to the extreme flexibility of graphene, which allows it to conform to the topography of even the smoothest substrates, thus making its interaction with the substrate more liquid-like than solid-like.Comment: to appear in Nature Nanotechnolog

Pairing symmetry and properties of iron-based high temperature superconductors

Pairing symmetry is important to indentify the pairing mechanism. The analysis becomes particularly timely and important for the newly discovered iron-based multi-orbital superconductors. From group theory point of view we classified all pairing matrices (in the orbital space) that carry irreducible representations of the system. The quasiparticle gap falls into three categories: full, nodal and gapless. The nodal-gap states show conventional Volovik effect even for on-site pairing. The gapless states are odd in orbital space, have a negative superfluid density and are therefore unstable. In connection to experiments we proposed possible pairing states and implications for the pairing mechanism.Comment: 4 pages, 1 table, 2 figures, polished versio

A Unified Approach to the Classical Statistical Analysis of Small Signals

We give a classical confidence belt construction which unifies the treatment of upper confidence limits for null results and two-sided confidence intervals for non-null results. The unified treatment solves a problem (apparently not previously recognized) that the choice of upper limit or two-sided intervals leads to intervals which are not confidence intervals if the choice is based on the data. We apply the construction to two related problems which have recently been a battle-ground between classical and Bayesian statistics: Poisson processes with background, and Gaussian errors with a bounded physical region. In contrast with the usual classical construction for upper limits, our construction avoids unphysical confidence intervals. In contrast with some popular Bayesian intervals, our intervals eliminate conservatism (frequentist coverage greater than the stated confidence) in the Gaussian case and reduce it to a level dictated by discreteness in the Poisson case. We generalize the method in order to apply it to analysis of experiments searching for neutrino oscillations. We show that this technique both gives correct coverage and is powerful, while other classical techniques that have been used by neutrino oscillation search experiments fail one or both of these criteria.Comment: 40 pages, 15 figures. Changes 15-Dec-99 to agree more closely with published version. A few small changes, plus the two substantive changes we made in proof back in 1998: 1) The definition of "sensitivity" in Sec. V(C). It was inconsistent with our actual definition in Sec. VI. 2) "Note added in proof" at end of the Conclusio

First Observation of the Decays chi_{cJ} -> pi^0 pi^0 pi^0 pi^0

We present a study of the P-wave spin -triplet charmonium chi_{cJ} decays (J=0,1,2) into pi^0 pi^0 pi^0 pi^0. The analysis is based on 106 million \psiprime decays recorded with the BESIII detector at the BEPCII electron positron collider. The decay into the pi^0 pi^0 pi^0 pi^0 hadronic final state is observed for the first time. We measure the branching fractions B(chi_{c0} -> pi^0 pi^0 pi^0 pi^0)=(3.34 +- 0.06 +- 0.44)*10^{-3}, B(chi_{c1} -> pi^0 pi^0 pi^0 pi^0)=(0.57 +- 0.03 +- 0.08)*10^{-3}, and B(chi_{c2} -> pi^0 pi^0 pi^0 pi^0)=(1.21 +- 0.05 +- 0.16)*10^{-3}, where the uncertainties are statistical and systematical, respectively.Comment: 7 pages, 3 figure

Observation of χc1\chi_{c1} decays into vector meson pairs ϕϕ\phi\phi, ωω\omega\omega, and ωϕ\omega\phi

Decays of $\chi_{c1}$ to vector meson pairs $\phi\phi$, $\omega\omega$ and $\omega\phi$ are observed for the first time using $(106\pm4)\times 10^6$ \psip events accumulated at the BESIII detector at the BEPCII $e^+e^-$ collider. The branching fractions are measured to be $(4.4\pm 0.3\pm 0.5)\times 10^{-4}$, $(6.0\pm 0.3\pm 0.7)\times 10^{-4}$, and $(2.2\pm 0.6\pm 0.2)\times 10^{-5}$, for $\chi_{c1}\to \phi\phi$, $\omega\omega$, and $\omega\phi$, respectively. The observation of $\chi_{c1}$ decays into a pair of vector mesons $\phi\phi$, $\omega\omega$ and $\omega\phi$ indicates that the hadron helicity selection rule is significantly violated in $\chi_{cJ}$ decays. In addition, the measurement of $\chi_{cJ}\to \omega\phi$ gives the rate of doubly OZI-suppressed decay. Branching fractions for $\chi_{c0}$ and $\chi_{c2}$ decays into other vector meson pairs are also measured with improved precision.Comment: 4 pages, 2 figure

Observation of Coherent Elastic Neutrino-Nucleus Scattering

The coherent elastic scattering of neutrinos off nuclei has eluded detection for four decades, even though its predicted cross-section is the largest by far of all low-energy neutrino couplings. This mode of interaction provides new opportunities to study neutrino properties, and leads to a miniaturization of detector size, with potential technological applications. We observe this process at a 6.7-sigma confidence level, using a low-background, 14.6-kg CsI[Na] scintillator exposed to the neutrino emissions from the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory. Characteristic signatures in energy and time, predicted by the Standard Model for this process, are observed in high signal-to-background conditions. Improved constraints on non-standard neutrino interactions with quarks are derived from this initial dataset