3,920 research outputs found

    Pair distribution functions calculated from interatomic potential models using the General Utility Lattice Program.

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    A new module has been developed for the widely used General Utility Lattice\ud Program (GULP). The phonon-based theory developed by Chung & Thorpe\ud [Phys. Rev. B (1999), 59, 4807ā€“4812] to calculate pair distribution function\ud (PDF) peak widths has been utilized to give a selection of commonly used\ud correlation functions. A numerical library of neutron scattering information is\ud now available within GULP, and is used to produce results that can be\ud compared with neutron scattering experimental data. The influence of different\ud phonon modes on the PDF can be assessed by excluding modes above or below\ud a cut-off frequency. Results are presented for sample crystallographic systems,\ud MgO, SrTiO3 and -cristobalite, as well as CaxSr1xTiO3 at x = 0.5, which makes\ud use of the capability to handle partial occupancies to compare different Ca/Sr\ud ordering arrangements with a disordered model in which every Ca/Sr site has\ud 50% occupancy of both species

    Effects of radiation on charge-coupled devices

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    The effects of 1 MeV electron irradiation upon the performance of two phase, polysilicon aluminum gate CCDs are reported. Both n- and p-surface channel and n-buried channel devices are investigated using 64- and 128-stage line arrays. Characteristics measured as a function of radiation dose include: Transfer inefficiency, threshold voltage, field effect mobility, interface state density, full well signal level and dark current. Surface channel devices are found to degrade considerably at less than 10 to the 5th power rads (Si) due to the large increase in fast interface state density caused by radiation. Buried channel devices maintain efficient operation to the highest dose levels used

    Growth, Condition, and Trophic Relations of Stocked Trout in Southern Appalachian Mountain Streams

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    Stream trout fisheries are among the most popular and valuable in the United States, but many are dependent on hatcheries to sustain fishing and harvest. Thus, understanding the ecology of hatcheryā€reared trout stocked in natural environments is fundamental to management. We evaluated the growth, condition, and trophic relations of Brook Trout Salvelinus fontinalis, Brown Trout Salmo trutta, and Rainbow Trout Oncorhynchus mykiss that were stocked in southern Appalachian Mountain streams in western North Carolina. Stocked and wild (naturalized) trout were sampled over time (monthly; September 2012ā€“June 2013) to compare condition and diet composition and to evaluate temporal dynamics of trophic position with stable isotope analysis. Relative weights (Wr) of stocked trout were inversely associated with their stream residence time but were consistently higher than those of wild trout. Weight loss of harvested stocked trout was similar among species and sizes, but fish stocked earlier lost more weight. Overall, 40% of 141 stomachs from stocked trout were empty compared to 15% of wild trout stomachs (N = 26). We identified a much higher rate of piscivory in wild trout (18 times that of stocked trout), and wild trout were 4.3 times more likely to consume gastropods relative to stocked trout. Hatcheryā€reared trout were isotopically similar to coā€occurring wild fish for both Ī“13C and Ī“15N values but were less variable than wild trout. Differences in sulfur isotope ratios (Ī“34S) between wild and hatcheryā€reared trout indicated that the diets of wild fish were enriched in Ī“34S relative to the diets of hatcheryā€reared fish. Although hatcheryreared trout consumed prey items similar to those of wild fish, differences in consumption or behavior (e.g., reduced feeding) may have resulted in lower condition and negative growth. These findings provide critical insight on the trophic dynamics of stocked trout and may assist in developing and enhancing stream trout fisheries

    Enhancing User Immersion and Virtual Presence in Interactive Multiuser Virtual Environments through the Development and Integration of a Gesture-Centric Natural User Interface Developed from Existing Virtual Reality Technologies

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    Immersion, referring to the level of physical or psychological submergence of a user within a virtual space relative to that user's consciousness of the real-world environment, has predominantly been established as an indispensable part of interactive media designs. This is most prevalent in Virtual Reality (VR) platforms, as their applications are typically reliant on user believability. With a wide variation of possible methodologies for the enhancement of this feature, the collectively recognised paradigm lies on the emphasis of naturalism in the design of the virtual system [7]. Though widely used by some specialised VR applications [4] such concepts are yet to be fully explored in the more contemporary virtual systems such as Social Immersive Virtual Environment (SIVE). The focus of the study described in this paper are the techniques being developed to enhance user immersion, virtual presence and co-presence in a SIVE application, through the design and integration of a VR-based Natural User Interface (NUI) that allows users to naturally and intuitively interact with the virtual environment and other networked users through the utilisation of full body gesture controls. These gestural controls prioritise the emulation of the alternate equivalent of such real-wold interactions, whilst also providing an interface for the seamless and unobtrusive translation of the user's real-world physical state into the virtual environment through intuitive user to virtual avatar proprioceptive coordination. Ā© Springer International Publishing Switzerland 2014

    Generation of folk song melodies using Bayes transforms

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    The paper introduces the `Bayes transform', a mathematical procedure for putting data into a hierarchical representation. Applicable to any type of data, the procedure yields interesting results when applied to sequences. In this case, the representation obtained implicitly models the repetition hierarchy of the source. There are then natural applications to music. Derivation of Bayes transforms can be the means of determining the repetition hierarchy of note sequences (melodies) in an empirical and domain-general way. The paper investigates application of this approach to Folk Song, examining the results that can be obtained by treating such transforms as generative models

    An analytical and experimental assessment of flexible road ironwork support structures

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    This paper describes work undertaken to investigate the mechanical performance of road ironwork installations in highways, concentrating on the chamber construction. The principal aim was to provide the background research which would allow improved designs to be developed to reduce the incidence of failures through improvements to the structural continuity between the installation and the surrounding pavement. In doing this, recycled polymeric construction materials (Jig Brix) were studied with a view to including them in future designs and specifications. This paper concentrates on the Finite Element (FE) analysis of traditional (masonry) and flexible road ironwork structures incorporating Jig Brix. The global and local buckling capacity of the Jig Brix elements was investigated and results compared well with laboratory measurements. FE models have also been developed for full-scale traditional (masonry) and flexible installations in a surrounding flexible (asphalt) pavement structure. Predictions of response to wheel loading were compared with full-scale laboratory measurements. Good agreement was achieved with the traditional (masonry) construction but poorer agreement for the flexible construction. Predictions from the FE model indicated that the use of flexible elements significantly reduces the tensile horizontal strain on the surface of the surrounding asphaltic material which is likely to reduce the incidence of surface cracking

    Criminal Law: Customerā€™s Permanent Exclusion From Retail Store Due to Prior Shoplifting Arrests Held Enforceable Under Criminal Trespass Statute

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    In interpretive research, trustworthiness has developed to become an important alternative for measuring the value of research and its effects, as well as leading the way of providing for rigour in the research process. The article develops the argument that trustworthiness plays an important role in not only effecting change in a research projectā€™s original setting, but also that trustworthy research contributes toward building a body of knowledge that can play an important role in societal change. An essential aspect in the development of this trustworthiness is its relationship to context. To deal with the multiplicity of meanings of context, we distinguish between contexts at different levels of the research project: the domains of the researcher, the collective, and the individual participant. Furthermore, we argue that depending on the primary purpose associated with the collective learning potential, critical potential, or performative potential of phenomenographic research, developing trustworthiness may take different forms and is related to aspects of pedagogical legitimacy, social legitimacy, and epistemological legitimacy. Trustworthiness in phenomenographic research is further analysed by distinguishing between the internal horizon ā€“ the constitution of trustworthiness as it takes place within the research project ā€“ and the external horizon, which points to the impact of the phenomenographic project in the world mediated by trustworthiness

    3D virtual worlds as environments for literacy learning

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    Background: Although much has been written about the ways in which new technology might transform educational practice, particularly in the area of literacy learning, there is relatively little empirical work that explores the possibilities and problems - or even what such a transformation might look like in the classroom. 3D virtual worlds offer a range of opportunities for children to use digital literacies in school, and suggest one way in which we might explore changing literacy practices in a playful, yet meaningful context. Purpose: This paper identifies some of the key issues that emerged in designing and implementing virtual world work in a small number of primary schools in the UK. It examines the tensions between different discourses about literacy and literacy learning and shows how these were played out by teachers and pupils in classroom settings.Sources of evidence: Case study data are used as a basis for exploring and illustrating key aspects of design and implementation. The case study material includes views from a number of perspectives including classroom observations, chatlogs, in-world avatar interviews with teachers and also pupils, as well as the authorā€™s field notes of the planning process with accompanying minutes and meeting documents.Main argument: From a Foucauldian perspective, the article suggests that social control of pedagogical practice through the regulation of curriculum time, the normalisation of teaching routines and the regimes of individual assessment restricts teachersā€™ and pupilsā€™ conceptions of what constitutes literacy. The counternarrative, found in recent work in new litearcies (Lankshear & Knobel, 2006) provides an attractive alternative, but a movement in this direction requires a fundamental shift of emphasis and a re-conceptualisation of what counts as learning.Conclusions: This work on 3D virtual worlds questions the notion of how transformative practice can be achieved with the use of new technologies. It suggests that changes in teacher preparation, continuing professional development as well as wider educational reform may be needed
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