Graphene as a Novel Single Photon Counting Optical and IR Photodetector

Bilayer graphene has many unique optoelectronic properties , including a tuneable band gap, that make it possible to develop new and more efficient optical and nanoelectronic devices. We have developed a Monte Carlo simulation for a single photon counting photodetector incorporating bilayer graphene. Our results show that, conceptually it would be feasible to manufacture a single photon counting photodetector (with colour sensitivity) from bilayer graphene for use across both optical and infrared wavelengths. Our concept exploits the high carrier mobility and tuneable band gap associated with a bilayer graphene approach. This allows for low noise operation over a range of cryogenic temperatures, thereby reducing the cost of cryogens with a trade off between resolution and operating temperature. The results from this theoretical study now enable us to progress onto the manufacture of prototype photon counters at optical and IR wavelengths that may have the potential to be groundbreaking in some scientific research applications.Comment: Conference Proceeding in Graphene-Based Technologies, 201

The future of bioethanol

Yeasts have been domesticated by mankind before horses. After the mastering of alcoholic fermentation for centuries, yeasts have become the protagonist of one of the most important biotechnological industries worldwide: the production of bioethanol. This chapter will initially present some important challenges to be overcome in this industry, both in first and second generation biofuel production. Then, it will briefly revisit some advances obtained in recent years. Finally, it will present and discuss some opportunities, in the scope of metabolic engineering and synthetic biology, that will likely be present in the future of bioethanol

Thermoelectric phenomena in disordered open quantum systems

Using a stochastic quantum approach, we study thermoelectric transport phenomena at low temperatures in disordered electrical systems connected to external baths. We discuss three different models of one-dimensional disordered electrons, namely the Anderson model of random on-site energies, the random-dimer model and the random-hopping model - also relevant for random-spin models. We find that although the asymptotic behavior of transport in open systems is closely related to that in closed systems for these noninteracting models, the magnitude of thermoelectric transport strongly depends on the boundary conditions and the baths spectral properties. This shows the importance of employing theories of open quantum systems in the study of energy transport.Comment: 5 pages, 2 figures, revised versio

3DQ: Compact Quantized Neural Networks for Volumetric Whole Brain Segmentation

Model architectures have been dramatically increasing in size, improving performance at the cost of resource requirements. In this paper we propose 3DQ, a ternary quantization method, applied for the first time to 3D Fully Convolutional Neural Networks (F-CNNs), enabling 16x model compression while maintaining performance on par with full precision models. We extensively evaluate 3DQ on two datasets for the challenging task of whole brain segmentation. Additionally, we showcase our method's ability to generalize on two common 3D architectures, namely 3D U-Net and V-Net. Outperforming a variety of baselines, the proposed method is capable of compressing large 3D models to a few MBytes, alleviating the storage needs in space critical applications.Comment: Accepted to MICCAI 201

NDT of Specimen of Complex Geometry Using Ultrasonic Adaptive Techniques - The F.A.U.S.T. System

Phased array techniques, providing an electronic control of the beam, are widely used in ultrasonic imaging. Such techniques, making use of array transducers with delayed transmission pulse on each element, allow to steer and focus the beam, enabling various testing configurations and imaging procedures : sector scanning and tomography, tracking echoes, depth focusing. In nuclear industry, various configurations of geometry and materials are encountered, which require many different testing configurations. The CEA (French Atomic Energy Commission) has developed an adaptive system based on phased array techniques dynamically controlled by a multi-channel acquisition system: theF.A.U.S.T. (Focusing Adaptive UltraSonic Tomography) system. This system aims at improving the performances of nondestructive testing, particularly for what concerns the adaptability to different control configurations and defect characterization. Previous works have described this system, its performances for beam forming and also its specific abilities for defect characterization using beam steering or spatial amplitude distribution at reception [1, 2]

Supercooling across first-order phase transitions in vortex matter

Hysteresis in cycling through first-order phase transitions in vortex matter, akin to the well-studied phenomenon of supercooling of water, has been discussed in literature. Hysteresis can be seen while varying either temperature T or magnetic field H (and thus the density of vortices). Our recent work on phase transitions with two control variables shows that the observable region of metastability of the supercooled phase would depend on the path followed in H-T space, and will be larger when T is lowered at constant H compared to the case when H is lowered at constant T. We discuss the effect of isothermal field variations on metastable supercooled states produced by field-cooling. This path dependence is not a priori applicable to metastability caused by reduced diffusivity or hindered kinetics.Comment: Tex, 8 pages, 3 Postscripts figures. Submitted to Pramana - J. Physic

Comparison of auctions and alternative policy options for RES-E support

This is the final version of the report. Available from AURES via the DOI in this record.This report summarises the findings of Task 6.2 of the AURES project. It intends to compare auctions with alternative policy instruments and examines under which circumstances auctions may be superior and inferior to achieve intended policy targets. Among an abundant list of potential policy drivers, which may affect an instrument’s effectiveness, its efficiency or further success criteria, the basis for the present analysis is the factor risk. It is demonstrated that risk constitutes an important factor as it may have decisive effects on societal welfare and thus may affect the decision-making of policy makers. Given a degree of uncertainty regarding the marginal costs and the marginal benefits of renewable support, particularly the choice between price and quantity-based instruments may yield different welfare effects. Both instruments expose policy makers to a risk of setting inefficient investment incentives. However, while price instruments may reduce the risk of welfare losses given a relatively steep marginal cost and a comparably flat marginal benefit curve, a quantity scheme may be superior if the relation between the two curves is vice versa. Building on this insight, our analysis reveals that the incentives for the use of policy instruments to support the deployment of RES are both country and technology specific. In general, it appears that the incentive to employ a quantity-based mean such as an auction is larger when the natural resources of the technology that is to be supported are abundant and if that technology is rather well developed. Moreover, since within a country the market and natural conditions of the different RES technologies and hence their supply costs may vary considerably, our findings provide an argument against a technology-neutral support.EU Horizon 2020 program, grant number 64617

The Ultrasonic Field of Focused Trandsucers Through a Liquid-Solid Interface

This paper presents theoretical and experimental results on the ultrasonic field of focused immersion transducers. The French Atomic Energy Commission (C.E.A.) has developed a software which calculates the ultrasonic field produced by a focused (or unfocused) transducer through a liquid-solid interface at normal or oblique incidence. The radiation of the transducer is formulated by the method of the Rayleigh integral, extended to take into account the liquid-solid interface. Firstly we describe this model, then we present measurements of the ultrasonic field produced by focused transducers in steel blocks. Experiments have been made using, at low frequencies, an electrodynamic probe, and, at high frequencies, an optical probe