19,374 research outputs found

    Perceived efficacy and attitudes towards genetic science and science governance

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    This is the postprint version of the Article. The official published version can be obtained from the link below - Ā© 2010 SAGE Publications.Arguments for public involvement in science and technology are often based on ideas of developing a more capable public and the assumed effects this may have for science. However, such a relationship is yet to be sufficiently explored and recent work indicates that a more involved public may have counterintuitive effects. Using nationally representative survey data for the UK and Northern Ireland, the effects of the public's own beliefs about involvement are explored. Developing the concept of "belief in public efficacy," findings suggest those who believe that the public might be able to affect the course of decision making have less approving attitudes towards future applications of genetic science; however, an individual's political efficacy does not significantly influence these attitudes. Furthermore, political efficacy and belief in public efficacy have some distinct and opposing relationships with the principles of governance people prefer. Overall, findings provide support for suggestions that it is simplistic to consider increasing public involvement as a way of increasing the approval of risky new technologies

    The Properties of the Hot Gas in Galaxy Groups and Clusters from 1-D Hydrodynamical Simulations -- I. Cosmological Infall Models

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    We report the results of 1-D hydrodynamical modelling of the evolution of gas in galaxy clusters. We have incorporated many of the effects missing from earlier 1-D treatments: improved modelling of the dark matter and galaxy distributions, cosmologically realistic evolution of the cluster potential, and the effects of a multiphase cooling flow. The model utilises a fairly standard 1-D Lagrangian hydrodynamical code to calculate the evolution of the intracluster gas. This is coupled to a theoretical model for the growth of dark matter density perturbations. The main advantages of this treatment over 3-D codes are (1) improved spatial resolution within the cooling flow region, (2) much faster execution time, allowing a fuller exploration of parameter space, and (3) the inclusion of additional physics. In the present paper, we explore the development of infall models -- in which gas relaxes into a deepening potential well -- covering a wide range of cluster mass scales. We find that such simple models reproduce many of the global properties of observed clusters. Very strong cooling flows develop in these 1-D cluster models. In practice, disruption by major mergers probably reduces the cooling rate in most clusters. The models overpredict the gas fraction in low mass systems, indicating the need for additional physical processes, such as preheating or galaxy winds, which become important on small mass scales.Comment: 38 pages, 21 encapsulated postscript figures, accepted for publication in MNRA

    One-way quantum computation with four-dimensional photonic qudits

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    We consider the possibility of performing linear optical quantum computation making use of extra photonic degrees of freedom. In particular we focus on the case where we use photons as quadbits. The basic 2-quadbit cluster state is a hyper-entangled state across polarization and two spatial mode degrees of freedom. We examine the non-deterministic methods whereby such states can be created from single photons and/or Bell pairs, and then give some mechanisms for performing higher-dimensional fusion gates.Comment: 10 figures (typos are corrected

    An unconfined, large-volume hydrogen/air explosion

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    Cause and results of the autoignition of 283 cubic meters of hydrogen gas, of which only about 10 percent exploded, are given. Results indicate that autoignition produces an explosion which could be described as a deflagration of explosive velocity, with a shock wave of sonic velocity and minor damage potential

    On the engineering of crucial software

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    The various aspects of the conventional software development cycle are examined. This cycle was the basis of the augmented approach contained in the original grant proposal. This cycle was found inadequate for crucial software development, and the justification for this opinion is presented. Several possible enhancements to the conventional software cycle are discussed. Software fault tolerance, a possible enhancement of major importance, is discussed separately. Formal verification using mathematical proof is considered. Automatic programming is a radical alternative to the conventional cycle and is discussed. Recommendations for a comprehensive approach are presented, and various experiments which could be conducted in AIRLAB are described

    Bioaccumulation of Methyl Mercury through a Food Chain

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    The bioaccumulation of mercury through the food chain has received much attention in Arkansas during the last three years. The discovery of mercury contamination and subsequent fish consumption advisories in southwest Arkansas have increased public awareness of the potential for bioaccumulation of different toxic compounds. It is postulated that the mercury problem in Arkansas is a result of methylation and resulting bioaccumulation of mercury as methyl mercury. This study was designed to derive a Bioaccumulation Factor (BAF) for mercury in a simple food chain under controlled conditions. A BAF is calculated by dividing the concentration found in the organism by the concentration found in the available food. The Producer trophic level was represented by the green alga, Selenastrum capricornutum. The Consumer trophic levels were represented by the water flea, Daphnia magna, and the Fathead Minnow, Pimephales promelas. Growth of the alga in media containing methyl mercury, followed by feeding the contaminated water fleas to the Fathead MInnows resulted in the derivation of BAF for each trophic level

    The implementation and use of Ada on distributed systems with high reliability requirements

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    The use and implementation of Ada in distributed environments in which reliability is the primary concern were investigated. In particular, the concept that a distributed system may be programmed entirely in Ada so that the individual tasks of the system are unconcerned with which processors they are executing on, and that failures may occur in the software or underlying hardware was examined. Progress is discussed for the following areas: continued development and testing of the fault-tolerant Ada testbed; development of suggested changes to Ada so that it might more easily cope with the failure of interest; and design of new approaches to fault-tolerant software in real-time systems, and integration of these ideas into Ada

    An Economic analysis of the potential for precision farming in UK cereal production

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    The results from alternative spatial nitrogen application studies are analysed in economic terms and compared to the costs of precision farming hardware, software and other services for cereal crops in the UK. At current prices, the benefits of variable rate application of nitrogen exceed the returns from a uniform application by an average of Ā£22 haāˆ’1 The cost of the precision farming systems range from Ā£5 to Ā£18 haāˆ’1 depending upon the system chosen for an area of 250 ha. The benefits outweigh the associated costs for cereal farms in excess of 80 ha for the lowest price system to 200ā€“300 ha for the more sophisticated systems. The scale of benefits obtained depends upon the magnitude of the response to the treatment and the proportion of the field that will respond. To be cost effective, a farmed area of 250 ha of cereals, where 30% of the area will respond to variable treatment, requires an increase in crop yield in the responsive areas of between 0Ā·25 and 1.00 t haāˆ’1 (at Ā£65 tāˆ’1) for the basic and most expensive precision farming systems, respectively

    Calcium signalling links MYC to NUAK1

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    NUAK1 is a member of the AMPK-related family of kinases. Recent evidence suggests that NUAK1 is an important regulator of cell adhesion and migration, cellular and organismal metabolism, and regulation of TAU stability. As such, NUAK1 may play key roles in multiple diseases ranging from neurodegeneration to diabetes and metastatic cancer. Previous work revealed a crucial role for NUAK1 in supporting viability of tumour cells specifically when MYC is overexpressed. This role is surprising, given that NUAK1 is activated by the tumour suppressor LKB1. Here we show that, in tumour cells lacking LKB1, NUAK1 activity is maintained by an alternative pathway involving calcium-dependent activation of PKCĪ±. Calcium/PKCĪ±-dependent activation of NUAK1 supports engagement of the AMPK-TORC1 metabolic checkpoint, thereby protecting tumour cells from MYC-driven cell death, and indeed, MYC selects for this pathway in part via transcriptional regulation of PKCĪ± and ITPR. Our data point to a novel role for calcium in supporting tumour cell viability and clarify the synthetic lethal interaction between NUAK1 and MYC

    Self-intersection local time of planar Brownian motion based on a strong approximation by random walks

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    The main purpose of this work is to define planar self-intersection local time by an alternative approach which is based on an almost sure pathwise approximation of planar Brownian motion by simple, symmetric random walks. As a result, Brownian self-intersection local time is obtained as an almost sure limit of local averages of simple random walk self-intersection local times. An important tool is a discrete version of the Tanaka--Rosen--Yor formula; the continuous version of the formula is obtained as an almost sure limit of the discrete version. The author hopes that this approach to self-intersection local time is more transparent and elementary than other existing ones.Comment: 36 pages. A new part on renormalized self-intersection local time has been added and several inaccuracies have been corrected. To appear in Journal of Theoretical Probabilit
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