Silicon Superconducting Quantum Interference Device

We have studied a Superconducting Quantum Interference SQUID device made from a single layer thin film of superconducting silicon. The superconducting layer is obtained by heavily doping a silicon wafer with boron atoms using the Gas Immersion Laser Doping (GILD) technique. The SQUID device is composed of two nano-bridges (Dayem bridges) in a loop and shows magnetic flux modulation at low temperature and low magnetic field. The overall behavior shows very good agreement with numerical simulations based on the Ginzburg-Landau equations.Comment: Published in Applied Physics Letters (August 2015

Alcohol enhances unprovoked 22-28 kHz USVs and suppresses USV mean frequency in High Alcohol Drinking (HAD-1) male rats

Heightened emotional states increase impulsive behaviors such as excessive ethanol consumption in humans. Though positive and negative affective states in rodents can be monitored in real-time through ultrasonic vocalization (USV) emissions, few animal studies have focused on the role of emotional status as a stimulus for initial ethanol drinking. Our laboratory has recently developed reliable, high-speed analysis techniques to compile USV data during multiple-hour drinking sessions. Since High Alcohol Drinking (HAD-1) rats are selectively bred to voluntarily consume intoxicating levels of alcohol, we hypothesized that USVs emitted by HAD-1 rats would reveal unique emotional phenotypes predictive of alcohol intake and sensitive to alcohol experience. In this study, male HAD-1 rats had access to water, 15% and 30% EtOH or water only (i.e., Controls) during 8 weeks of daily 7-h drinking-in-the-dark (DID) sessions. USVs, associated with both positive (i.e., 50-55 kHz frequency-modulated or FM) and negative (i.e., 22-28 kHz) emotional states, emitted during these daily DID sessions were examined. Findings showed basal 22-28 kHz USVs were emitted by both EtOH-Naïve (Control) and EtOH-experienced rats, alcohol experience enhanced 22-28 kHz USV emissions, and USV acoustic parameters (i.e., mean frequency in kHz) of both positive and negative USVs were significantly suppressed by chronic alcohol experience. These data suggest that negative affective status initiates and maintains excessive alcohol intake in selectively bred HAD-1 rats and support the notion that unprovoked emissions of negative affect-associated USVs (i.e., 22-28 kHz) predict vulnerability to excessive alcohol intake in distinct rodent models

Sex differences in cognitive performance and alcohol consumption in High Alcohol-Drinking (HAD-1) rats

Excessive alcohol (ethanol) consumption negatively impacts social, emotional, as well as cognitive function and well-being. Thus, identifying behavioral and/or biological predictors of excessive ethanol consumption is important for developing prevention and treatment strategies against alcohol use disorders (AUDs). Sex differences in alcohol consumption patterns are observed in humans, primates, and rodents. Selectively bred high alcohol-drinking rat lines, such as the “HAD-1” lines are recognized animal models of alcoholism. The present work examined sex differences in alcohol consumption, object recognition, and exploratory behavior in male and female HAD-1 rats. Naïve male and female HAD-1 rats were tested in an object recognition test (ORT) prior to a chronic 24 h intermittent ethanol access procedure for five weeks. Object recognition parameters measured included exploratory behavior, object investigation, and time spent near objects. During the initial training trial, rearing, active object investigation and amount of time spent in the object-containing section was significantly greater in female HAD-1 rats compared to their male counterparts. During the subsequent testing trial, time spent in the object-containing section was greater in female, compared to male, rats; but active object investigation and rearing did not statistically differ between females and males. In addition, female HAD-1 rats consumed significantly more ethanol than their male counterparts, replicating previous findings. Moreover, across all animals there was a significant positive correlation between exploratory behavior in ORT and ethanol consumption level. These results indicate there are significant sex differences in cognitive performance and alcohol consumption in HAD-1 rats, which suggests neurobiological differences as well

Deep learning-based defect detection in industrial CT volumes of castings

International audienceIndustrial X-ray computed tomography (CT) has proven to be one of the most powerful non-destructive testing (NDT) methods for the inspection of light metal castings. The generated CT volume allows for the internal and external geometry of the specimen to be measured, casting defects to be localised and their statistical properties to be investigated. On the other hand, CT volumes are very prone to artefacts that can be mistaken for defects by conventional segmentation algorithms. These artefacts require trained operators to distinguish them from real defects, which makes CT inspection very time consuming if it is to be implemented on the production line. Foundries using this inspection method are constantly looking for a module that can perform this interpretation automatically. Based on CT data of aluminium alloy automotive and aerospace specimens provided by industrial partners, an automated approach for the analysis of discontinuities inside CT volumes is developed in this paper based on a two-stage pipeline: 2D segmentation of CT slices with automatic deep segmentation using U-Net to detect suspicious greyscale discontinuities; and classification of these discontinuities into true alarms (defects) or false alarms (artefacts and noise) using a new convolutional neural network classifier called CT-Casting-Net. The choice of each model and the training results are presented and discussed, as well as the efficiency of the approach as an automatic defect detection algorithm for industrial CT volumes using metrics relevant to the field of non-destructive testing. The approach is tested on six new CT volumes with 301 defects and achieves an object-level recall of 99%, a precision of 87% and a voxel-level intersection-over-union (IoU) of 62%

Quantum Coherence of the Quartet Scheme Observed by Shapiro Resonance Under Radio-Frequency Irradiation in Three Terminal Josephson Junctions

International audienceWe have investigated three-terminal superconductor (S)-normal metal (N)-superconductor (S) Josephson junctions. In a geometry where a T-shaped normal metal (Cu) is connected to three superconducting reservoirs (Al), new subgap structures appear in the differential resistance when the bias voltages on two of the three terminals compensate each other exactly. These features correspond to the correlated motion of Cooper pairs within the structure. They are consistent with the prediction of quartets formed by the simultaneous splitting of two Cooper pairs at one of the superconducting contacts and the emission of two phase correlated Cooper pairs in the two other electrodes. To test the quantum coherence of such mechanism, we have studied the effect of a radio-frequency irradiation at 14 GHz down to 100 mK. Well known Shapiro steps involving two terminals are measured, and in particular, half-integer steps are observed. This is consistent with the transfer of two Cooper pairs between two terminals. This paper reveals that the quartet resonances also show Shapiro steps in agreement with the quartet mechanism. Our findings confirm the quartet scenario and demonstrate its coherent nature

X-ray imaging plate performance investigation based on a Monte Carlo simulation tool

International audienceComputed radiography (CR) based on imaging plate (IP) technology represents a potential replacement technique for traditional film-based industrial radiography. For investigating the IP performance especially at high energies, a Monte Carlo simulation tool based on PENELOPE has been developed. This tool tracks separately direct and secondary radiations, and monitors the behavior of different particles. The simulation output provides 3D distribution of deposited energy in IP and evaluation of radiation spectrum propagation allowing us to visualize the behavior of different particles and the influence of different elements. A detailed analysis, on the spectral and spatial responses of IP at different energies up to MeV, has been performed