The structure of 110 tilt boundaries in large area solar silicon

The models of Hornstra and their connection to the repeating group description of grain boundaries (7-10) are discussed. A model for the Sigma = 27 boundary containing a zig-zag arrangement of dislocations is constructed and it is shown that zig-zag models can account for the contrast features observed in high resolution transmission electron micrographs of second and third order twin boundaries in silicon. The boundaries discussed are symmetric with a 110 tilt axis and a (110) boundary plane in the median lattice (the median plane). The median lattice is identical in structure and halfway in orientation between the crystal lattices either side of the boundary

A genome-wide association study demonstrates significant genetic variation for fracture risk in Thoroughbred racehorses

Background: Thoroughbred racehorses are subject to non-traumatic distal limb bone fractures that occur during racing and exercise. Susceptibility to fracture may be due to underlying disturbances in bone metabolism which have a genetic cause. Fracture risk has been shown to be heritable in several species but this study is the first genetic analysis of fracture risk in the horse. Results: Fracture cases (n = 269) were horses that sustained catastrophic distal limb fractures while racing on UK racecourses, necessitating euthanasia. Control horses (n = 253) were over 4 years of age, were racing during the same time period as the cases, and had no history of fracture at the time the study was carried out. The horses sampled were bred for both flat and National Hunt (NH) jump racing. 43,417 SNPs were employed to perform a genome-wide association analysis and to estimate the proportion of genetic variance attributable to the SNPs on each chromosome using restricted maximum likelihood (REML). Significant genetic variation associated with fracture risk was found on chromosomes 9, 18, 22 and 31. Three SNPs on chromosome 18 (62.05 Mb – 62.15 Mb) and one SNP on chromosome 1 (14.17 Mb) reached genome-wide significance (p <0.05) in a genome-wide association study (GWAS). Two of the SNPs on ECA 18 were located in a haplotype block containing the gene zinc finger protein 804A (ZNF804A). One haplotype within this block has a protective effect (controls at 1.95 times less risk of fracture than cases, p = 1 × 10-4), while a second haplotype increases fracture risk (cases at 3.39 times higher risk of fracture than controls, p = 0.042). Conclusions: Fracture risk in the Thoroughbred horse is a complex condition with an underlying genetic basis. Multiple genomic regions contribute to susceptibility to fracture risk. This suggests there is the potential to develop SNP-based estimators for genetic risk of fracture in the Thoroughbred racehorse, using methods pioneered in livestock genetics such as genomic selection. This information would be useful to racehorse breeders and owners, enabling them to reduce the risk of injury in their horses

Processing Bi-Pb-Sr-Ca-Cu-O superconductors from amorphous state

The bismuth based high T sub c superconductors can be processed via an amorphous Bi-Pb-Sr-Ca-Cu oxide. The amorphous oxides were prepared by melting the constituent powders in an alumina crucible at 1200 C in air followed by pouring the liquid onto an aluminum plate, and rapidly pressing with a second plate. In the amorphous state, no crystalline phase was identified in the powder x ray diffraction pattern of the quenched materials. After heat treatment at high temperature the amorphous materials crystallized into a glass ceramic containing a large fraction of the Bi2Sr2Ca2Cu3O(x) phase T sub c = 110 K. The processing method, crystallization, and results of dc electrical resistivity and ac magnetic susceptibility measurements are discussed

RPGR protein complex regulates proteasome activity and mediates store-operated calcium entry

Ciliopathies are a group of genetically heterogeneous disorders, characterized by defects in cilia genesis or maintenance. Mutations in the RPGR gene and its interacting partners, RPGRIP1 and RPGRIP1L, cause ciliopathies, but the function of their proteins remains unclear. Here we show that knockdown (KD) of RPGR, RPGRIP1 or RPGRIP1L in hTERT-RPE1 cells results in abnormal actin cytoskeleton organization. The actin cytoskeleton rearrangement is regulated by the small GTPase RhoA via the planar cell polarity (PCP) pathway. RhoA activity was upregulated in the absence of RPGR, RPGRIP1 or RPGRIP1L proteins. In RPGR, RPGRIP1 or RPGRIP1L KD cells, we observed increased levels of DVl2 and DVl3 proteins, the core components of the PCP pathway, due to impaired proteasomal activity. RPGR, RPGRIP1 or RPGRIP1L KD cells treated with thapsigargin (TG), an inhibitor of sarcoendoplasmic reticulum Ca2+ - ATPases, showed impaired store-operated Ca2+ entry (SOCE), which is mediated by STIM1 and Orai1 proteins. STIM1 was not localized to the ER-PM junction upon ER store depletion in RPGR, RPGRIP1 or RPGRIP1L KD cells. Our results demonstrate that the RPGR protein complex is required for regulating proteasomal activity and for modulating SOCE, which may contribute to the ciliopathy phenotype

Phase Transformations in the High-Tc Superconducting Compounds, Ba_2RCu_3O_(7–δ) (R = Nd, Sm, Gd, Y, Ho, and Er)

The phase transformation between the orthorhombic and tetragonal structures of six high-Tc superconductors, Ba2RCu3O7−δ, where R = Nd, Sm, Gd, Y, Ho, and Er, and δ = 0 to 1, has been investigated using techniques of x-ray diffraction, differential thermal analysis/thermogravimetric analysis (DTA/TGA) and electron diffraction. The transformation from the oxygen-rich orthorhombic phase to the oxygen-deficient tetragonal phase involves two orthorhombic phases. A superlattice cell caused by oxygen ordering, with a′ = 2a, was observed for materials with smaller ionic radius (Y, Ho, and Er). For the larger lanthanide samples (Nd, Sm, and Gd), the a′ = 2a type superlattice cell was not observed. The structural phase transition temperatures, oxygen stoichiometry and characteristics of the Tc plateaus appear to correlate with the ionic radius, which varies based on the number of f electrons. Lanthanide elements with a smaller ionic radius stabilize the orthorhombic phase to higher temperatures and lower oxygen content. Also, the superconducting temperature is less sensitive to the oxygen content for materials with smaller ionic radius. The trend of dependence of the phase transformation temperature on ionic radius across the lanthanide series can be explained using a quasi-chemical approximation (QCA) whereby the strain effect plays an important role on the order-disorder transition due to the effect of oxygen content on the CuO chain sites

Cardiomyocyte overexpression of neuronal nitric oxide synthase delays transition toward heart failure in response to pressure overload by preserving calcium cycling.

International audienceBACKGROUND: Defects in cardiomyocyte Ca(2+) cycling are a signature feature of heart failure (HF) that occurs in response to sustained hemodynamic overload, and they largely account for contractile dysfunction. Neuronal nitric oxide synthase (NOS1) influences myocyte excitation-contraction coupling through modulation of Ca(2+) cycling, but the potential relevance of this in HF is unknown. METHODS AND RESULTS: We generated a transgenic mouse with conditional, cardiomyocyte-specific NOS1 overexpression (double-transgenic [DT]) and studied cardiac remodeling, myocardial Ca(2+) handling, and contractility in DT and control mice subjected to transverse aortic constriction (TAC). After TAC, control mice developed eccentric hypertrophy with evolution toward HF as revealed by a significantly reduced fractional shortening. In contrast, DT mice developed a greater increase in wall thickness (P<0.0001 versus control+TAC) and less left ventricular dilatation than control+TAC mice (P<0.0001 for both end-systolic and end-diastolic dimensions). Thus, DT mice displayed concentric hypertrophy with fully preserved fractional shortening (43.7+/-0.6% versus 30.3+/-2.6% in control+TAC mice, P<0.05). Isolated cardiomyocytes from DT+TAC mice had greater shortening, intracellular Ca(2+) transients, and sarcoplasmic reticulum Ca(2+) load (P<0.05 versus control+TAC for all parameters). These effects could be explained, at least in part, through modulation of phospholamban phosphorylation status. CONCLUSIONS: Cardiomyocyte NOS1 may be a useful target against cardiac deterioration during chronic pressure-overload-induced HF through modulation of calcium cycling

Département de la Charente

Quel que soit le type de voie de communication, terrestre ou fluviale, leur étude est primordiale pour mieux comprendre et appréhender l’habitat en milieu rural. Au cours de l’année, nous avons souhaité étudier et reconnaître les moyens d’accès à la villa de Marsac alias Marciacum (Marcius ou Martius auquel est apposé le suffixe acum) déjà répertoriée par nos soins il y a plusieurs années. À cet effet, nous sommes partis de la voie Agrippa qui sépare les communes de Montignac-Charente et Vars..

A unified programming system for a multi-paradigm parallel architecture

Real time image understanding and image generation require very large amounts of computing power. A possible way to meet these requirements is to make use of the power available from parallel computing systems. However parallel machines exhibit performance which is highly dependent on the algorithms being executed. Both image understanding and image generation involve the use of a wide variety of algorithms. A parallel machine suited to some of these algorithms may be unsuited to others. This thesis describes a novel heterogeneous parallel architecture optimised for image based applications. It achieves its performance by combining two different forms of parallel architecture, namely fine grain SIMD and course grain MIMD, into a single architecture. In this way it is possible to match the most appropriate computing resource to each algorithm in a given application. As important as the architecture itself is a method for programming it. This thesis describes a novel multi-paradigm programming language based on C++, which allows programs which make use of both control and data parallelism to be expressed in a single coherent framework, based on object oriented programming. To demonstrate the utility of both the architecture and the programming system, two applications, one from the field of image understanding the other image generation are examined. These applications combine some novel algorithms with other novel implementation approaches to provide the most effective mapping onto this architecture