Regularity for the near field parallel refractor and reflector problems

We prove local $C^{1,\alpha}$ estimates of solutions for the parallel refractor and reflector problems under local assumptions on the target set $\Sigma$, and no assumptions are made on the smoothness of the densities.Comment: 32 pages, three figure

Flow analysis and control in a subsonic inlet

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2005.Includes bibliographical references (leaves 109-113).S-duct inlets are commonly used on subsonic cruise missiles, as they offer a good compromise between compactness, low observability and aerodynamic performance. Though currently used S-ducts exhibit good performance in terms of distortion and pressure recovery at the AIP, the situation can degrade drastically when the inlet is put in off-design conditions, with the risk of compressor instabilities. Flow control is considered as a promising way to maintain inlet efficiency in off-design flight conditions. Industrial interest for flow control techniques is therefore rising, and a need for their comparative evaluation has been expressed. In response to this need, an experimental setup has been designed and fabricated, and flow control experiments have been carried out at MIT, on the selected off-design case of forebody boundary layer ingestion. The first set of experiments focused on the characterization of the inlet in a clean configuration. Then, a distortion device was added in order to simulate thick forebody boundary layer. This proved to have a strong detrimental effect on the inlet performance, as the separation bubble grew in size, the pressure recovery dropped down and the distortion level increased drastically. The selected flow control techniques were then implemented. .(cont.) The Vortex Generators, tried in different configurations, did improve the pressure recovery and significantly decrease the distortion level. They had a strong impact on the flow structure, delaying or even suppressing separation. Injection was done with Coanda-type injectors, upstream of the separation line. Steady injection led to significant improvement of the pressure recovery, which increased with increasing injection mass flow. Separation was eliminated at least for the highest injection mass flows. The distortion level decreased with increasing injection mass flow. Overall, the results also highlighted the importance of the secondary flows as a source of distortion and pressure recovery lossby Serge Tournier.S.M

Évolution de la qualité de vie après un traumatisme crânien par accident de la route : un suivi à cinq ans de la cohorte ESPARR

Continua com: Info Ajuntament+Sostenible : notícies de l'Ajuntament+sostenibl

Electronic Instability in a Zero-Gap Semiconductor: The Charge-DensityWave in (TaSe4)(2)I

We report a comprehensive study of the paradigmatic quasi-1D compound (TaSe4)(2)I performed by means of angle-resolved photoemission spectroscopy (ARPES) and first-principles electronic structure calculations. We find it to be a zero-gap semiconductor in the nondistorted structure, with non-negligible interchain coupling. Theory and experiment support a Peierls-like scenario for the charge-density wave formation below T-CDW = 263 K, where the incommensurability is a direct consequence of the finite interchain coupling. The formation of small polarons, strongly suggested by the ARPES data, explains the puzzling semiconductor-to-semiconductor transition observed in transport at T-CDW.open114sciescopu

Glass transition in biomolecules and the liquid-liquid critical point of water

Using molecular dynamics simulations, we investigate the relation between the dynamic transitions of biomolecules (lysozyme and DNA) and the dynamic and thermodynamic properties of hydration water. We find that the dynamic transition of the macromolecules, sometimes called a ``protein glass transition'', occurs at the temperature of dynamic crossover in the diffusivity of hydration water, and also coincides with the maxima of the isobaric specific heat $C_P$ and the temperature derivative of the orientational order parameter. We relate these findings to the hypothesis of a liquid-liquid critical point in water. Our simulations are consistent with the possibility that the protein glass transition results from crossing the Widom line, which is defined as the locus of correlation length maxima emanating from the hypothesized second critical point of water.Comment: 10 Pages, 12 figure

Giant ambipolar Rashba effect in a semiconductor: BiTeI

We observe a giant spin-orbit splitting in bulk and surface states of the non-centrosymmetric semiconductor BiTeI. We show that the Fermi level can be placed in the valence or in the conduction band by controlling the surface termination. In both cases it intersects spin-polarized bands, in the corresponding surface depletion and accumulation layers. The momentum splitting of these bands is not affected by adsorbate-induced changes in the surface potential. These findings demonstrate that two properties crucial for enabling semiconductor-based spin electronics -- a large, robust spin splitting and ambipolar conduction -- are present in this material.Comment: 4 pages, 3 figure

Evaluating 35 Methods to Generate Structural Connectomes Using Pairwise Classification

There is no consensus on how to construct structural brain networks from diffusion MRI. How variations in pre-processing steps affect network reliability and its ability to distinguish subjects remains opaque. In this work, we address this issue by comparing 35 structural connectome-building pipelines. We vary diffusion reconstruction models, tractography algorithms and parcellations. Next, we classify structural connectome pairs as either belonging to the same individual or not. Connectome weights and eight topological derivative measures form our feature set. For experiments, we use three test-retest datasets from the Consortium for Reliability and Reproducibility (CoRR) comprised of a total of 105 individuals. We also compare pairwise classification results to a commonly used parametric test-retest measure, Intraclass Correlation Coefficient (ICC).Comment: Accepted for MICCAI 2017, 8 pages, 3 figure