Intermittency of glassy relaxation and the emergence of a non-equilibrium spontaneous measure in the aging regime

We consider heat exchange processes between non-equilibrium aging systems (in their activated regime) and the thermal bath in contact. We discuss a scenario where two different heat exchange processes concur in the overall heat dissipation: a stimulated fast process determined by the temperature of the bath and a spontaneous intermittent process determined by the fact that the system has been prepared in a non-equilibrium state. The latter is described by a probability distribution function (PDF) that has an exponential tail of width given by a parameter $\lambda$, and satisfies a fluctuation theorem (FT) governed by that parameter. The value of $\lambda$ is proportional to the so-called effective temperature, thereby providing a practical way to experimentally measure it by analyzing the PDF of intermittent events.Comment: Latex file, 8 pages + 5 postscript figure

Evidence of two-dimensional macroscopic quantum tunneling of a current-biased DC-SQUID

The escape probability out of the superconducting state of a hysteretic DC-SQUID has been measured at different values of the applied magnetic flux. At low temperature, the escape current and the width of the probability distribution are temperature independent but they depend on flux. Experimental results do not fit the usual one-dimensional (1D) Macroscopic Quantum Tunneling (MQT) law but are perfectly accounted for by the two-dimensional (2D) MQT behaviour as we propose here. Near zero flux, our data confirms the recent MQT observation in a DC-SQUID \cite{Li02}.Comment: 4 pages, 4 figures Accepted to PR

First experimental evidence of one-dimensional plasma modes in superconducting thin wires

We have studied niobium superconducting thin wires deposited onto a SrTiO$_{3}$ substrate. By measuring the reflection coefficient of the wires, resonances are observed in the superconducting state in the 130 MHz to 4 GHz range. They are interpreted as standing wave resonances of one-dimensional plasma modes propagating along the superconducting wire. The experimental dispersion law, $\omega$ versus $q$, presents a linear dependence over the entire wave vector range. The modes are softened as the temperature increases close the superconducting transition temperature. Very good agreement are observed between our data and the dispersion relation predicted by Kulik and Mooij and Sch\"on.Comment: Submitted to Physical review Letter

Design and User Satisfaction of Interactive Maps for Visually Impaired People

Multimodal interactive maps are a solution for presenting spatial information to visually impaired people. In this paper, we present an interactive multimodal map prototype that is based on a tactile paper map, a multi-touch screen and audio output. We first describe the different steps for designing an interactive map: drawing and printing the tactile paper map, choice of multi-touch technology, interaction technologies and the software architecture. Then we describe the method used to assess user satisfaction. We provide data showing that an interactive map - although based on a unique, elementary, double tap interaction - has been met with a high level of user satisfaction. Interestingly, satisfaction is independent of a user's age, previous visual experience or Braille experience. This prototype will be used as a platform to design advanced interactions for spatial learning

Do Mirrors for Gravitational Waves Exist?

Thin superconducting films are predicted to be highly reflective mirrors for gravitational waves at microwave frequencies. The quantum mechanical non-localizability of the negatively charged Cooper pairs, which is protected from the localizing effect of decoherence by an energy gap, causes the pairs to undergo non-picturable, non-geodesic motion in the presence of a gravitational wave. This non-geodesic motion, which is accelerated motion through space, leads to the existence of mass and charge supercurrents inside the superconducting film. On the other hand, the decoherence-induced localizability of the positively charged ions in the lattice causes them to undergo picturable, geodesic motion as they are carried along with space in the presence of the same gravitational wave. The resulting separation of charges leads to a virtual plasma excitation within the film that enormously enhances its interaction with the wave, relative to that of a neutral superfluid or any normal matter. The existence of strong mass supercurrents within a superconducting film in the presence of a gravitational wave, dubbed the "Heisenberg-Coulomb effect," implies the specular reflection of a gravitational microwave from a film whose thickness is much less than the London penetration depth of the material, in close analogy with the electromagnetic case. The argument is developed by allowing classical gravitational fields, which obey Maxwell-like equations, to interact with quantum matter, which is described using the BCS and Ginzburg-Landau theories of superconductivity, as well as a collisionless plasma model. Several possible experimental tests of these ideas, including mesoscopic ones, are presented alongside comments on the broader theoretical implications of the central hypothesis.Comment: 59 pages, 2 figure

Contribution to the Berkner scheme for the approximation of the continuous wavelet transform: application to the measure of the latency time of the genioglossus muscle

The continuous wavelet transform is widely used in signal processing. It enables to choose significant scales with respect to detection and localization purposes. Berkner transform is an approximation of the continuous wavelet transform for which we propose an original synthesis formula. We then build a detector of reflex activity in EMG signals using Berkner transform. The significant scales are determined through the use of the reconstruction formula. The electromyographic measurement of the reflex activity of the genioglossus muscle under stimulation is of great interest for the study of sleep apnea. The reflex activity is a complex mixture of unpredictable nonstationary events that are surimposed on a stationary background containing noisy transients. The detector of reflex activity we propose is both robust and accurate. We end up the paper with a statistical analysis of the detector performances on synthetic signals and we give an illustration of the method on real signals.La transformée continue en ondelettes est un outil trés utilisé pour la détection de transitions dans les signaux. Elle permet un choix souple des échelles pertinentes vis à vis des objectifs de détection et de localisation des événements. Nous introduisons ici une approximation de la transformée continue en ondelettes, la transformée de Berkner, pour laquelle nous proposons une formule de reconstruction originale du signal. Nous appliquons ensuite cette transformée à la construction d'un détecteur d'événements réflexes dans les signaux EMG. Les échelles pertinentes utilisées par le détecteur sont sélectionnées en utilisant la formule de reconstruction. La mesure électromyographique (EMG) du temps de latence réflexe du muscle génioglosse en réponse à l'application d'une pression pharyngée négative est d'un grand intérêt dans l'étude physiopathologique du syndrome d'apnée du sommeil. Cette activité réflexe est un mélange complexe de signaux transitoires non prédictibles apparaissant dans une activité de fond stationnaire bruitée par des transitoires parasites. Le détecteur proposé permet une détection robuste de l'événement réflexe et une estimation précise du temps d'occurrence. Une analyse statistique des performances du détecteur sur signaux synthétiques est présentée ainsi qu'une illustration de détection sur des EMG réels

Entanglement and decoherence of a micromechanical resonator via coupling to a Cooper box

We analyse the quantum dynamics of a micromechanical resonator capacitively coupled to a Cooper box. With appropriate quantum state control of the Cooper box, the resonator can be driven into a superposition of spatially separated states. The Cooper box can also be used to probe the environmentally-induced decoherence of the resonator superposition state.Comment: 4 pages, 3 figure

High mortality associated with an outbreak of hepatitis E among displaced persons in Darfur, Sudan

BACKGROUND: Hepatitis E virus (HEV) causes acute onset of jaundice and a high case-fatality ratio in pregnant women. We provide a clinical description of hospitalized case patients and assess the specific impact on pregnant women during a large epidemic of HEV infection in a displaced population in Mornay camp (78,800 inhabitants), western Darfur, Sudan. METHODS: We reviewed hospital records. A sample of 20 clinical cases underwent laboratory confirmation. These patients were tested for immunoglobulin G (IgG) and immunoglobulin M (IgM) antibody to HEV (serum) and for amplification of the HEV genome (serum and stool). We performed a cross-sectional survey in the community to determine the attack rate and case-fatality ratio in pregnant women. RESULTS: Over 6 months, 253 HEV cases were recorded at the hospital, of which 61 (24.1%) were in pregnant women. A total of 72 cases (39.1% of those for whom clinical records were available) had a diagnosis of hepatic encephalopathy. Of the 45 who died (case-fatality ratio, 17.8%), 19 were pregnant women (specific case-fatality ratio, 31.1%). Acute hepatitis E was confirmed in 95% (19/20) of cases sampled; 18 case-patients were positive for IgG (optical density ratio > or =3), for IgM (optical density ratio >2 ), or for both, whereas 1 was negative for IgG and IgM but positive for HEV RNA in serum. The survey identified 220 jaundiced women among the 1133 pregnant women recorded over 3 months (attack rate, 19.4%). A total of 18 deaths were recorded among these jaundiced pregnant women (specific case-fatality ratio, 8.2%). CONCLUSIONS: This large epidemic of HEV infection illustrates the dramatic impact of this disease on pregnant women. Timely interventions and a vaccine are urgently needed to prevent mortality in this special group

Flux Confinement in Mesoscopic Superconductors

We report on flux confinement effects in superconducting submicron line, loop and dot structures. The main idea of our study was to vary the boundary conditions for confinement of the superconducting condensate by taking samples of different topology and, through that, modifying the lowest Landau level E_{LLL}(H). Since the critical temperature versus applied magnetic field T_{c}(H) is, in fact, E_{LLL}(H) measured in temperature units, it is varied as well when the sample topology is changed. We demonstrate that in all studied submicron structures the shape of the T_{c}(H) phase boundary is determined by the confinement topology in a unique way.Comment: 10 pages, 5 EPS figures, uses LaTeX's sup.sty, contribution to a special issue of "Superlattices and Microstructures