570 research outputs found

    Generating direct manipulation program editors

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    Language specific editors are cognisant of the syntax and semantics of the programming language they manipulate. Despite the various potential advantages of language specific editors, they have not been widely accepted by software developers for serious software development. On the other hand direct manipulation editors, which are also cognisant of the entities they manipulate, have proven to be successful in other domains such as drawing and VLSI design tools. Thus, it is worth while investigating the incorporation of direct manipulation mechanisms into program editors. This paper presents a technique for specifying direct manipulation editing of programs which is amenable to the generation of language specific editors incorporating direct manipulation from a specification of the desired editing mechanisms

    Whither the Language Lab?

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    Language Labs have experienced many changes over thepast several years, from changes in names to changes in direction.This edited transcription of a panel discussion at the1994 TESOL conference by six experienced language lab directorsprovides an informal and free-wheeling discussionabout the following questions: (1) What's in a name (change)?(2) What is the most appropriate role for technology with respectto language learning and teaching? (3) What is the roleof the language lab vis-a-vis faculty and adminis tration? (4)What are students' perceptions of language labs? (5) Whathas had the greatest impact on language labs over the last tento twenty years? (6) What are the fundamental characteristicsof the ideal lab director? (7) What is the greatest challengefacing the language lab today, as well as into the next decade?(8) Whither the language lab? What direction do we see ourselvesmoving in the next generation

    Thermal instabilities in cooling galactic coronae: fuelling star formation in galactic discs

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    We investigate the means by which cold gas can accrete onto Milky Way mass galaxies from a hot corona of gas, using a new smoothed particle hydrodynamics code, 'SPHS'. We find that the 'cold clumps' seen in many classic SPH simulations in the literature are not present in our SPHS simulations. Instead, cold gas condenses from the halo along filaments that form at the intersection of supernovae-driven bubbles from previous phases of star formation. This positive feedback feeds cold gas to the galactic disc directly, fuelling further star formation. The resulting galaxies in the SPH and SPHS simulations differ greatly in their morphology, gas phase diagrams, and stellar content. We show that the classic SPH cold clumps owe to a numerical thermal instability caused by an inability for cold gas to mix in the hot halo. The improved treatment of mixing in SPHS suppresses this instability leading to a dramatically different physical outcome. In our highest resolution SPHS simulation, we find that the cold filaments break up into bound clumps that form stars. The filaments are overdense by a factor of 10-100 compared to the surrounding gas, suggesting that the fragmentation results from a physical non-linear instability driven by the overdensity. This 'fragmenting filament' mode of disc growth has important implications for galaxy formation, in particular the role of star formation in bringing cold gas into disc galaxies.Comment: 20 pages, 12 figures. Submitted to MNRAS. A better formatted version of the PDF is available at http://www.astro.phys.ethz.ch/~ahobbs/papers/coolinghalospaper.pdf . Movies (highly recommended viewing) available at http://www.phys.ethz.ch/~ahobbs/movies.htm

    Structure of human saposin A at lysosomal pH.

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    The saposins are essential cofactors for the normal lysosomal degradation of complex glycosphingolipids by acid hydrolase enzymes; defects in either saposin or hydrolase function lead to severe metabolic diseases. Saposin A (SapA) activates the enzyme β-galactocerebrosidase (GALC), which catalyzes the breakdown of β-D-galactocerebroside, the principal lipid component of myelin. SapA is known to bind lipids and detergents in a pH-dependent manner; this is accompanied by a striking transition from a `closed' to an `open' conformation. However, previous structures were determined at non-lysosomal pH. This work describes a 1.8 Å resolution X-ray crystal structure determined at the physiologically relevant lysosomal pH 4.8. In the absence of lipid or detergent at pH 4.8, SapA is observeed to adopt a conformation closely resembling the previously determined `closed' conformation, showing that pH alone is not sufficient for the transition to the `open' conformation. Structural alignments reveal small conformational changes, highlighting regions of flexibility.CHH is funded by a Wellcome Trust PhD studentship, RJR is supported by a Principal Research Fellowship funded by the Wellcome Trust (Grant No. 082961/Z/07/Z) and JED is supported by a Royal Society University Research Fellowship (UF100371). The Cambridge Institute for Medical Research is supported by a Wellcome Trust Strategic Award (100140).This is the final version of the article. It first appeared from Wiley via http://dx.doi.org/10.1107/S2053230X1500858

    On the role of the AIS practitioner

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    Cognisant of the gulf between engineers and immunologists that currenty hinders a truly inter-disciplinary approach to the field of Artificial Immune Systems (AIS), we propose a redefinition of the term AIS practitioner, as an individual who identifies those components and interactions captured in computational immunology models that are responsible for a particular property of interest (POI), and distils from these a set of algorithms and principles that can be applied in an engineering domain. We outline the role of the cross-disciplinary practitioner and the potential benefits to the field

    Considerations for selecting field-based strength and power fitness tests to measure asymmetries

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    The prevalence of lower limb asymmetries has been reported in numerous studies; however, methodological differences exist in the way they can be detected. Strength and jumping-based tasks have been most commonly used to examine these differences across both athlete and non-athlete populations. The aim of this review was to critically analyze the utility of strength and jumping tests that are frequently used to measure asymmetry. Reliability, validity, and considerations for assessment are examined to enhance test accuracy and effectiveness in the quantification of asymmetries during strength and jumping-based tasks. Medline and SPORT Discus databases were used with specific search terms to identify relevant articles in both athlete and non-athlete populations. The findings of the current review indicate that assessing inter-limb differences during strength and jumping-based tasks may result in different levels of asymmetry; thus, inter-limb differences appear to be task-dependent. Consequently, quantification during both types of assessment is warranted and a selection of tests has been suggested to measure asymmetries in both strength and jumping-based tasks

    On the role of the AIS practitioner

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    Cognisant of the gulf between engineers and immunologists that currenty hinders a truly inter-disciplinary approach to the field of Artificial Immune Systems (AIS), we propose a redefinition of the term AIS practitioner, as an individual who identifies those components and interactions captured in computational immunology models that are responsible for a particular property of interest (POI), and distils from these a set of algorithms and principles that can be applied in an engineering domain. We outline the role of the cross-disciplinary practitioner and the potential benefits to the field
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