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

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

Unmet Need for Nutrition-Related Services in Recently Hospital-Discharged Older Adults

Older adults returning home from the hospital may have disabilities that prevent them from obtaining or preparing adequate nutritious food. Additionally, they may have difficulty identifying their need for or accessing services that could provide support. We aimed to identify the level of unmet need for services that may affect nutritional health in community-dwelling older adults. We also compared the prevalence of perceived need for services with objectively assessed need. We explored the need for home health care, transportation, mental health, oral health, vision, grocery delivery, and physical therapy services in 566 community-dwelling, recently hospital-discharged older adults. Almost half (45.6%) of the sample reported unmet need for at least one service. For each service, there was discrepancy between perceived need and assessed need. By improving the screening of hospital-discharged older adults' needs for nutrition-related services, the healthcare community can improve targeting of services to those with the most nutritional risk

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

Geographic and species association of hepatitis B virus genotypes in non-human primates

AbstractInfection with hepatitis B virus (HBV) has been detected in human populations thoughout the world, as well as in a number of ape species (Pan troglodytes, Gorilla gorilla, gibbons [Nomascus and Hylobates species] and Pongo pygmaeus). To investigate the distribution of naturally occurring HBV infection in these species and other African Old World monkey species (Cercopithecidae), we screened 137 plasma samples from mainly wild caught animals by polymerase chain reaction (PCR) using several of highly conserved primers from the HB surface (HBs) gene, and for HBs antigen (HBsAg) by ELISA. None of the 93 Cercopithecidae screened (6 species) showed PCR or serology evidence for HBV infection; in contrast 2 from 8 chimpanzees and 5 from 22 gibbons were PCR-positive with each set of primers.Complete genome sequences from each of the positive apes were obtained and compared with all previously published complete and surface gene sequences. This extended phylogenetic analysis indicated that HBV variants from orangutans were interspersed by with HBV variants from southerly distributed gibbon species (H. agilis and H. moloch) occupying overlapping or adjacent habitat ranges with orangutans; in contrast, HBV variants from gibbon species in mainland Asia were phylogenetically distinct. A geographical rather than (sub)species association of HBV would account for the distribution of HBV variants in different subspecies of chimpanzees in Africa, and explain the inlier position of the previously described lowland gorilla sequence in the chimpanzee clade. These new findings have a number of implication for understanding the origins and epidemiology of HBV infection in non-human primates

Neuro-glial plasticity of neuroendocrine networks

Neuro-glial plasticity of neuroendocrine networks is a major mechanism involved in key events of physiological functions such as parturition and lactation (oxytocinergic system) and preovulatory surge (GnRH system). This type of plasticity is classically described as rearrangements between glial cells and neuroendocrine neurones. Neuro-glial plasticity can occur within several hours. Cellular and molecular mechanisms involved are complex and imply an active regulation of neuroendocrine networks activity. In the present study we show that GnRH pulsatile secretion studied in vitro is regulated by gap junction communication between glial cells. Glial cells forming the microenvironment of GnRH neuronal network could represent a new system for integrating environmental cues and for regulating GnRH secretionLa plasticité neuro-gliale des réseaux neuroendocrines est un élément majeur de la régulation d’évènements clés de grandes fonctions, comme la plasticité du système ocytocinergique lors de la parturition et de la lactation et celle du système GnRH dans le déclenchement du pic pré-ovulatoire de LH. Cette plasticité est décrite par des réarrangements neuroanatomiques des cellules gliales associées aux neurones neuroendocrines. Elle peut se mettre en place en quelques heures. Les mécanismes cellulaires et moléculaires sont complexes et mettent en jeu une régulation active de l’activité des neurones par les cellules gliales. Dans l’étude présentée ici, nous montrons que la pulsatilité de sécrétion des neurones à GnRH étudiés in vitro est régulée par la communication des cellules gliales via des jonctions gap. Les cellules gliales du microenvironnement des neurones à GnRH pourraient ainsi représenter un nouveau système d’intégration des signaux environnementaux et de régulation de la sécrétion de GnR