2,950 research outputs found

    The Minority’s Duty of Loyalty in Close Corporations

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    In situ measurements of density fluctuations and compressibility in silica glass as a function of temperature and thermal history

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    In this paper, small-angle X-ray scattering measurements are used to determine the different compressibility contributions, as well as the isothermal compressibility, in thermal equilibrium in silica glasses having different thermal histories. Using two different methods of analysis, in the supercooled liquid and in the glassy state, we obtain respectively the temperature and fictive temperature dependences of the isotheraml compressibility. The values obtained in the glass and supercooled liquid states are very close to each other. They agree with previous determinations of the literature. The compressibility in the glass state slightly decreases with increasing fictive temperature. The relaxational part of the compressibility is also calculated and compared to previous determinations. We discussed the small differences between the different determinations

    Three-Body approach to the K^- d Scattering Length in Particle Basis

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    We report on the first calculation of the scattering length A_{K^-d} based on a relativistic three-body approach where the two-body input amplitudes coupled to the Kbar N channels have been obtained with the chiral SU(3) constraint, but with isospin symmetry breaking effects taken into account. Results are compared with a recent calculation applying a similar set of two-body amplitudes,based on the fixed center approximation, considered as a good approximation for a loosely bound target, and for which we find significant deviations from the exact three-body results. Effects of the hyperon-nucleon interaction, and deuteron DD-wave component are also evaluated.Comment: 5 pages, Submitted to Phys. Rev.

    Communicating Hunger and Satiation in the First Two Years of Life: A Systematic Review

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    Responsive feeding has been identified as important in preventing overconsumption by infants. However, this is predicated on an assumption that parents recognise and respond to infant feeding cues. Despite this, relatively little is understood about how infants engage parental feeding responses. Therefore the aim of this systematic review was to identify what is known about infant communication of hunger and satiation and what issues impact on the expression and perception of these states. A search of Medline, CINAHL, Web of Science, PsycINFO, Science Direct and Maternal and Infant care produced 27 papers. Eligibility criteria included: peer reviewed qualitative and/or quantitative publications on feeding behaviours, hunger, satiation/satiety cues of typically developing children in the first two years of life. Papers published between 1966 and 2013 were included in the review. The review revealed that feeding cues and behaviours are shaped by numerous issues, such as infants’ physical attributes, individual psychological factors and environmental factors. Meanwhile, infant characteristics, external cues and mothers’ own characteristics affect how feeding cues are perceived. The existing literature provides insights into many aspects of hunger and satiation in infancy; however, there are significant gaps in our knowledge. There is a lack of validated tools for measuring hunger and satiation, a need to understand how different infant characteristics impact on feeding behaviour and a need to extricate the respective contributions of infant and maternal characteristics to perceptions of hunger and satiation. Further research is also recommended to differentiate between feeding driven by liking and that driven by hunger

    Testing the durability of limestone for Cathedral façade restoration

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    This research aimed to specify an optimum replacement stone for Truro Cathedral. A variety of petrographically and visually similar material to the original Bath stone was initially selected. The stones were subjected to three different durability tests; Sodium sulphate crystallisation and large scale testing with both accelerated and climatic freeze-thaw cyclic loading. The most suitable stone was determined as the one with the best performance characteristics overall

    Summary of the First Workshop on Sustainable Software for Science: Practice and Experiences (WSSSPE1)

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    Challenges related to development, deployment, and maintenance of reusable software for science are becoming a growing concern. Many scientists’ research increasingly depends on the quality and availability of software upon which their works are built. To highlight some of these issues and share experiences, the First Workshop on Sustainable Software for Science: Practice and Experiences (WSSSPE1) was held in November 2013 in conjunction with the SC13 Conference. The workshop featured keynote presentations and a large number (54) of solicited extended abstracts that were grouped into three themes and presented via panels. A set of collaborative notes of the presentations and discussion was taken during the workshop. Unique perspectives were captured about issues such as comprehensive documentation, development and deployment practices, software licenses and career paths for developers. Attribution systems that account for evidence of software contribution and impact were also discussed. These include mechanisms such as Digital Object Identifiers, publication of “software papers”, and the use of online systems, for example source code repositories like GitHub. This paper summarizes the issues and shared experiences that were discussed, including cross-cutting issues and use cases. It joins a nascent literature seeking to understand what drives software work in science, and how it is impacted by the reward systems of science. These incentives can determine the extent to which developers are motivated to build software for the long-term, for the use of others, and whether to work collaboratively or separately. It also explores community building, leadership, and dynamics in relation to successful scientific software

    The Evolution of Calcium-Based Signalling in Plants

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    The calcium-based intracellular signalling system is used ubiquitously to couple extracellular stimuli to their characteristic intracellular responses. It is becoming clear from genomic and physiological investigations that while the basic elements in the toolkit are common between plants and animals, evolution has acted in such a way that, in plants, some components have diversified with respect to their animal counterparts, while others have either been lost or have never evolved in the plant lineages. In comparison with animals, in plants there appears to have been a loss of diversity in calcium-influx mechanisms at the plasma membrane. However, the evolution of the calcium-storing vacuole may provide plants with additional possibilities for regulating calcium influx into the cytosol. Among the proteins that are involved in sensing and responding to increases in calcium, plants possess specific decoder proteins that are absent from the animal lineage. In seeking to understand the selection pressures that shaped the plant calcium-signalling toolkit, we consider the evolution of fast electrical signalling. We also note that, in contrast to animals, plants apparently do not make extensive use of cyclic-nucleotide-based signalling. It is possible that reliance on a single intracellular second-messenger-based system, coupled with the requirement to adapt to changing environmental conditions, has helped to define the diversity of components found in the extant plant calcium-signalling toolkit

    Characterization of the glass transition in vitreous silica by temperature scanning small-angle X-ray scattering

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    The temperature dependence of the x-ray scattering in the region below the first sharp diffraction peak was measured for silica glasses with low and high OH content (GE-124 and Corning 7980). Data were obtained upon scanning the temperature at 10, 40 and 80 K/min between 400 K and 1820 K. The measurements resolve, for the first time, the hysteresis between heating and cooling through the glass transition for silica glass, and the data have a better signal to noise ratio than previous light scattering and differential thermal analysis data. For the glass with the higher hydroxyl concentration the glass transition is broader and at a lower temperature. Fits of the data to the Adam-Gibbs-Fulcher equation provide updated kinetic parameters for this very strong glass. The temperature derivative of the observed X-ray scattering matches that of light scattering to within 14%.Comment: EurophysicsLetters, in pres

    Simulating `Complex' Problems with Quantum Monte Carlo

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    We present a new quantum Monte Carlo algorithm suitable for generically complex problems, such as systems coupled to external magnetic fields or anyons in two spatial dimensions. We find that the choice of gauge plays a nontrivial role, and can be used to reduce statistical noise in the simulation. Furthermore, it is found that noise can be greatly reduced by approximate cancellations between the phases of the (gauge dependent) statistical flux and the external magnetic flux.Comment: Revtex, 11 pages. 3 postscript files for figures attache
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