Characteristics of III-V Semiconductor Devices at High Temperature

This paper presents the development of III-V based pseudomorphic high electron mobility transistors (PHEMT's) designed to operate over the temperature range 77 to 473 K (-196 to 200 C). These devices have a pseudomorphic undoped InGaAs channel that is sandwiched between an AlGaAs spacer and a buffer layer; gate widths of 200, 400, 1600, and 3200 micrometers; and a gate length of 2 micrometers. Measurements were performed at both room temperature and 473 K (200 C) and show that the drain current decreases by 30 percent and the gate current increases to about 9 microns A (at a reverse bias of -1.5 V) at the higher temperature. These devices have a maximum DC power dissipation of about 4.5 W and a breakdown voltage of about 16 V

Knockdown of Ant2 Reduces Adipocyte Hypoxia And Improves Insulin Resistance in Obesity.

Decreased adipose tissue oxygen tension and increased HIF-1α expression can trigger adipose tissue inflammation and dysfunction in obesity. Our current understanding of obesity-associated decreased adipose tissue oxygen tension is mainly focused on changes in oxygen supply and angiogenesis. Here, we demonstrate that increased adipocyte O2 demand, mediated by ANT2 activity, is the dominant cause of adipocyte hypoxia. Deletion of adipocyte Ant2 improves obesity-induced intracellular adipocyte hypoxia by decreasing obesity-induced adipocyte oxygen demand, without effects on mitochondrial number or mass, or oligomycin-sensitive respiration. This led to decreased adipose tissue HIF-1α expression and inflammation with improved glucose tolerance and insulin resistance in both a preventative or therapeutic setting. Our results suggest that ANT2 may be a target for the development of insulin sensitizing drugs and that ANT2 inhibition might have clinical utility

Properties of the Broad-Range Nematic Phase of a Laterally Linked H-Shaped Liquid Crystal Dimer

In search for novel nematic materials, a laterally linked H-shaped liquid crystal dimer have been synthesized and characterized. The distinct feature of the material is a very broad temperature range (about 50 oC) of the nematic phase, which is in contrast with other reported H-dimers that show predominantly smectic phases. The material exhibits interesting textural features at the scale of nanometers (presence of smectic clusters) and at the macroscopic scales. Namely, at a certain temperature, the flat samples of the material show occurrence of domain walls. These domain walls are caused by the surface anchoring transition and separate regions with differently tilted director. Both above and below this transition temperature the material represents a uniaxial nematic, as confirmed by the studies of defects in flat samples and samples with colloidal inclusions, freely suspended drops, X-ray diffraction and transmission electron microscopy.Comment: 30 pages (including Supplementary Information), 7 Figure

Exome Sequence Analysis of 14 Families With High Myopia

PURPOSE: To identify causal gene mutations in 14 families with autosomal dominant (AD) high myopia using exome sequencing. METHODS: Select individuals from 14 large Caucasian families with high myopia were exome sequenced. Gene variants were filtered to identify potential pathogenic changes. Sanger sequencing was used to confirm variants in original DNA, and to test for disease cosegregation in additional family members. Candidate genes and chromosomal loci previously associated with myopic refractive error and its endophenotypes were comprehensively screened. RESULTS: In 14 high myopia families, we identified 73 rare and 31 novel gene variants as candidates for pathogenicity. In seven of these families, two of the novel and eight of the rare variants were within known myopia loci. A total of 104 heterozygous nonsynonymous rare variants in 104 genes were identified in 10 out of 14 probands. Each variant cosegregated with affection status. No rare variants were identified in genes known to cause myopia or in genes closest to published genome-wide association study association signals for refractive error or its endophenotypes. CONCLUSIONS: Whole exome sequencing was performed to determine gene variants implicated in the pathogenesis of AD high myopia. This study provides new genes for consideration in the pathogenesis of high myopia, and may aid in the development of genetic profiling of those at greatest risk for attendant ocular morbidities of this disorder

Cognitive Information Processing

Contains reports on six research projects.National Institutes of Health (Grant 1 PO1 GM-14940-01)National Institutes of Health (Grant 1 PO1 GM-15006-01)Joint Services Electronics Programs (U. S. Army, U. S. Navy, and U. S. Air Force) under Contract DA 28-043-AMC-02536(E)Project MAC, an M. I. T. research programAdvanced Research Projects Agency, Department of Defense, under Office of Naval Research Contract Nonr-4102-(01

Toward an integrative understanding of social behavior: new models and new opportunities.

Social interactions among conspecifics are a fundamental and adaptively significant component of the biology of numerous species. Such interactions give rise to group living as well as many of the complex forms of cooperation and conflict that occur within animal groups. Although previous conceptual models have focused on the ecological causes and fitness consequences of variation in social interactions, recent developments in endocrinology, neuroscience, and molecular genetics offer exciting opportunities to develop more integrated research programs that will facilitate new insights into the physiological causes and consequences of social variation. Here, we propose an integrative framework of social behavior that emphasizes relationships between ultimate-level function and proximate-level mechanism, thereby providing a foundation for exploring the full diversity of factors that underlie variation in social interactions, and ultimately sociality. In addition to identifying new model systems for the study of human psychopathologies, this framework provides a mechanistic basis for predicting how social behavior will change in response to environmental variation. We argue that the study of non-model organisms is essential for implementing this integrative model of social behavior because such species can be studied simultaneously in the lab and field, thereby allowing integration of rigorously controlled experimental manipulations with detailed observations of the ecological contexts in which interactions among conspecifics occur

Assessing computer skills in Tanzanian medical students: an elective experience.

BACKGROUND: One estimate suggests that by 2010 more than 30% of a physician's time will be spent using information technology tools. The aim of this study is to assess the information and communication technologies (ICT) skills of medical students in Tanzania. We also report a pilot intervention of peer mentoring training in ICT by medical students from the UK tutoring students in Tanzania. DESIGN: Cross sectional study and pilot intervention study. PARTICIPANTS: Fourth year medical students (n = 92) attending Muhimbili University College of Health Sciences, Dar es Salaam, Tanzania. MAIN OUTCOME MEASURES: Self-reported assessment of competence on ICT-related topics and ability to perform specific ICT tasks. Further information related to frequency of computer use (hours per week), years of computer use, reasons for use and access to computers. Skills at specific tasks were reassessed for 12 students following 4 to 6 hours of peer mentoring training. RESULTS: The highest levels of competence in generic ICT areas were for email, Internet and file management. For other skills such as word processing most respondents reported low levels of competence. The abilities to perform specific ICT skills were low - less than 60% of the participants were able to perform the core specific skills assessed. A period of approximately 5 hours of peer mentoring training produced an approximate doubling of competence scores for these skills. CONCLUSION: Our study has found a low level of ability to use ICT facilities among medical students in a leading university in sub-Saharan Africa. A pilot scheme utilising UK elective students to tutor basic skills showed potential. Attention is required to develop interventions that can improve ICT skills, as well as computer access, in order to bridge the digital divide

Constellations of identity: place-ma(r)king beyond heritage

This paper will critically consider the different ways in which history and belonging have been treated in artworks situated in the Citadel development in Ayr on the West coast of Scotland. It will focus upon one artwork, Constellation by Stephen Hurrel, as an alternative to the more conventional landscapes of heritage which are adjacent, to examine the relationship between personal history and place history and argue the primacy of participatory process in the creation of place and any artwork therein. Through his artwork, Hurrel has attempted to adopt a material process through which place can be created performatively but, in part due to its non-representational form, proves problematic, aesthetically and longitudinally, in wholly engaging the community. The paper will suggest that through variants of ‘new genre public art’ such as this, personal and place histories can be actively re-created through the redevelopment of contemporary urban landscapes but also highlight the complexities and indeterminacies involved in the relationship between artwork, people and place