16,210 research outputs found

    Properties of the mechanosensitive channel MscS pore revealed by tryptophan scanning mutagenesis

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    Funding This work was supported by a Wellcome Trust Programme grant [092552/A/10/Z awarded to I.R.B., S.M., J. H. Naismith (University of St Andrews, St Andrews, U.K.), and S. J. Conway (University of Oxford, Oxford, U.K.)] (T.R. and M.D.E.), by a BBSRC grant (A.R.) [BB/H017917/1 awarded to I.R.B., J. H. Naismith, and O. Schiemann (University of St Andrews)], by a Leverhulme Emeritus Fellowship (EM-2012-060\2), and by a CEMI grant to I.R.B. from the California Institute of Technology. The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007-2013 FP7/2007-2011) under Grant PITN-GA-2011-289384 (FP7-PEOPLE-2011-ITN NICHE) (H.G.) (awarded to S.M.).Peer reviewedPublisher PD

    New approaches to the measurement of chlorophyll, related pigments and productivity in the sea

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    In the 1984 SBIR Call for Proposals, NASA solicited new methods to measure primary production and chlorophyll in the ocean. Biospherical Instruments Inc. responded to this call with a proposal first to study a variety of approaches to this problem. A second phase of research was then funded to pursue instrumentation to measure the sunlight stimulated naturally occurring fluorescence of chlorophyll in marine phytoplankton. The monitoring of global productivity, global fisheries resources, application of above surface-to-underwater optical communications systems, submarine detection applications, correlation, and calibration of remote sensing systems are but some of the reasons for developing inexpensive sensors to measure chlorophyll and productivity. Normally, productivity measurements are manpower and cost intensive and, with the exception of a very few expensive multiship research experiments, provide no contemporaneous data. We feel that the patented, simple sensors that we have designed will provide a cost effective method for large scale, synoptic, optical measurements in the ocean. This document is the final project report for a NASA sponsored SBIR Phase 2 effort to develop new methods for the measurements of primary production in the ocean. This project has been successfully completed, a U.S. patent was issued covering the methodology and sensors, and the first production run of instrumentation developed under this contract has sold out and been delivered

    Shuttle GPS R/PA evaluation analysis and performance tradeoff study

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    Primary responsibility was understanding and analyzing the various GPS receiver functions as they relate to the shuttle environment. These receiver functions included acquisition properties of the sequential detector, acquisition and tracking properties of the various receiver phase locked loops, and the techniques of sequential receiver operation. In addition to these areas, support was provided in the areas of oscillator stability requirements, antenna management, and navigation filter requirements, including preposition aiding

    The synthesis of some acylglycines and related oxazolones

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    Shuttle GPS R/PA configuration and specification study

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    Changes in the technical specifications for a global positioning system (GPS) receiving system dedicated to space shuttle use are presented. Various hardware functions including acquisition, tracking, and measurement are emphasized. The anti-jam performance of the baseline GPS systems are evaluated. Other topics addressed include: the impact on R/PA design of the use of ground based transmitters; problems involved with the use of single channel tests sets; utility of various R/PA antenna interconnections topologies; the choice of the averaging interval for delta range measurements; and the use of interferometry techniques for the computation of orbiter attitude were undertaken

    The Weight of Opinion - The early childhood sector's perceptions about childhood overweight and obesty

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    Early childhood is a critical time in a child’s development when the foundations for good or poor eating habits and self-regulation of appetite are laid. Because long day care centres and preschools structure the daily environment in which the children in their care play and learn, the early childhood sector can make an important contribution to preventing and (sometimes) dealing with childhood overweight and obesity. Whether through the direct provision of food at child care or rules/suggestions surrounding the food that children are to bring to preschool, they exert some control over what children consume while in their care. Similarly, they control the amount of active play time that is available during the day. Long day care centres and preschools may also incorporate messages about healthy eating and the benefits of active play into their curriculum, and may provide modelling of good eating habits by the teachers/workers during snack or meal times. They may also regulate the kinds of fundraising opportunities used to support their preschools/centres (e.g. no chocolates or donut fundraisers), and provide parents with information and support regarding the development of healthy habits. This report presents the findings from a series of in-depth interviews on the perceptions of early childhood staff about the issue of childhood overweight and obesity and their role in supporting healthy eating and active play.Interviews were conducted with eleven directors and staff members from four long day care centres and four preschools, located in three areas within metropolitan Sydney and one area in rural NSW. The results show that the early childhood educators recognise childhood overweight and obesity as a serious issue and appreciate the complexity of the causes of the increasing prevalence of overweight. They viewed these issues as part of their core mission as early childhood educators, and worked under a philosophy of close partnership with families (and, in some cases, with local health professionals). All of the participants also acknowledged that parents can be sensitive about their children’s weight, that there can be uncertainty surrounding definitions of overweight among young children, and that there can be emotions around the provision of food and children’s eating patterns. At the same time, interviewees recognised that the early childhood sector can only do so much by themselves and that their efforts need to be complemented by efforts to support parents and change cultural and environmental factors that make it difficult to eat healthy foods and get adequate physical activity, especially considering the fact that not all children have access to or participate in early childhood education. However, given the large proportion of children and parents who do have contact with the early childhood sector, the potential to strengthen the role of the sector in preventing childhood overweight and obesity and promoting healthy eating and active play was highlighted in the research. The interviewees gave practical suggestions for how that could occur. They wanted more early childhood-friendly games, activities, books, songs, and posters about healthy eating and physical activity, more resources they could give directly to parents, more guidance on optimal nutrition policies (for preschools), more training for themselves (including information on when to be concerned about children’s weight and what to do about it), and more access to health professionals who could come and speak to them and the parents.This research was funded by NSW Health and The Ross Family Trust. Principal Investigators: Dr Michael Booth and Lesley King. The authors would like to thank Louise Erickson for her valuable contribution to this project, as well as all the preschools and child care centres who participated in the study

    Analysis of Novel Mechanosensitive Channel Activities in Escherichia Coli

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    Hypergraph Acyclicity and Propositional Model Counting

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    We show that the propositional model counting problem #SAT for CNF- formulas with hypergraphs that allow a disjoint branches decomposition can be solved in polynomial time. We show that this class of hypergraphs is incomparable to hypergraphs of bounded incidence cliquewidth which were the biggest class of hypergraphs for which #SAT was known to be solvable in polynomial time so far. Furthermore, we present a polynomial time algorithm that computes a disjoint branches decomposition of a given hypergraph if it exists and rejects otherwise. Finally, we show that some slight extensions of the class of hypergraphs with disjoint branches decompositions lead to intractable #SAT, leaving open how to generalize the counting result of this paper

    Horizon energy and angular momentum from a Hamiltonian perspective

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    Classical black holes and event horizons are highly non-local objects, defined in terms of the causal past of future null infinity. Alternative, (quasi)local definitions are often used in mathematical, quantum, and numerical relativity. These include apparent, trapping, isolated, and dynamical horizons, all of which are closely associated to two-surfaces of zero outward null expansion. In this paper we show that three-surfaces which can be foliated with such two-surfaces are suitable boundaries in both a quasilocal action and a phase space formulation of general relativity. The resulting formalism provides expressions for the quasilocal energy and angular momentum associated with the horizon. The values of the energy and angular momentum are in agreement with those derived from the isolated and dynamical horizon frameworks.Comment: 39 pages, 3 figures, Final Version : content essentially unchanged but many small improvements made in response to referees, a few references adde
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