19,595 research outputs found

    Variational approximations to homoclinic snaking

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    We investigate the snaking of localised patterns, seen in numerous physical applications, using a variational approximation. This method naturally introduces the exponentially small terms responsible for the snaking structure, that are not accessible via standard multiple-scales asymptotic techniques. We obtain the symmetric snaking solutions and the asymmetric 'ladder' states, and also predict the stability of the localised states. The resulting approximate formulas for the width of the snaking region show good agreement with numerical results.Comment: 4 pages, 3 figures, submitte

    Technical pre-analytical effects on the clinical biochemistry of Atlantic salmon (Salmo salar L.)

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    Clinical biochemistry has long been utilized in human and veterinary medicine as a vital diagnostic tool, but despite occasional studies showing its usefulness in monitoring health status in Atlantic salmon (Salmo salar L.), it has not yet been widely utilized within the aquaculture industry. This is due, in part, to a lack of an agreed protocol for collection and processing of blood prior to analysis. Moreover, while the analytical phase of clinical biochemistry is well controlled, there is a growing understanding that technical pre-analytical variables can influence analyte concentrations or activities. In addition, post-analytical interpretation of treatment effects is variable in the literature, thus making the true effect of sample treatment hard to evaluate. Therefore, a number of pre-analytical treatments have been investigated to examine their effect on analyte concentrations and activities. In addition, reference ranges for salmon plasma biochemical analytes have been established to inform veterinary practitioners and the aquaculture industry of the importance of clinical biochemistry in health and disease monitoring. Furthermore, a standardized protocol for blood collection has been proposed

    Fluxon analogues and dark solitons in linearly coupled Bose-Einstein condensates

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    Two effectively one-dimensional parallel coupled Bose-Einstein condensates in the presence of external potentials are studied. The system is modelled by linearly coupled Gross-Pitaevskii equations. In particular, grey-soliton-like solutions representing analogues of superconducting Josephson fluxons as well as coupled dark solitons are discussed. Theoretical approximations based on variational formulations are derived. It is found that the presence of a magnetic trap can destabilize the fluxon analogues. However, stabilization is possible by controlling the effective linear coupling between the condensates.Comment: 14 pages, 7 figures, The paper is to appear in Journal of Physics

    Integrating Scientific Knowledge for Professional Education in Environmental Management

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    A major challenge in developing programmes for professional education in environmental management is presented by the need to determine how the vast amount of scientific and professional knowledge required for effective environmental management can be efficiently transmitted to prospective or practising ‘environmental coordinators' in the private and public sectors of society. This paper describes the work conducted at M.I.T., in collaboration with C.E.I., to provide a conceptual and substantive base for such programmes. The conceptual framework is based on a simplified model of the decision-making steps in environmental management processes. Such a model can be used for isolating certain types of decisions and roles in different social, cultural, administrative, or political, contexts. When once this has been done, the responsibilities and the educational needs of specific classes of ‘environmental managers' can be identified through studies and interviews. The substantive base for new educational programmes requires the development of outlines and the identification of reference material for the major bodies of knowledge that comprise the ‘field' of environmental management. This paper briefly describes the major subject-areas treated in this study: values and perceptions, ecology, environmental effects, environmental indicators, environmental impact assessment methodology, modelling, monitoring, growth and its implications for the future, economics of externalities, environmental law, and administrative processes. The approach and materials described in this paper are now being used at C.E.I, in the development of educational programmes for practising professionals, and at M.I.T. for graduate and undergraduate students in a variety of disciplines. Thus far, these efforts have been well received and have provided additional information with which to continue designing additional programme

    Computer generated animation and movie production at LARC: A case study

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    The process of producing computer generated 16mm movies using the MOVIE.BYU software package developed by Brigham Young University and the currently available hardware technology at the Langley Research Center is described. A general overview relates the procedures to a specific application. Details are provided which describe the data used, preparation of a storyboard, key frame generation, the actual animation, title generation, filming, and processing/developing the final product. Problems encountered in each of these areas are identified. Both hardware and software problems are discussed along with proposed solutions and recommendations

    Experiences and perceptions of Spring Lane Sure Start Children's Centre

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    Spring Lane Sure Start Children’s Centre was designated in September 2007, and ‘officially opened’ in February 2009. The Centre is housed in refurbished premises within a nursery/school complex in the heart of Northampton and offers diverse health, childcare, early education and support services delivered by a multi-professional team. These services and activities are available to children aged 0-5 years old, and their parents/carers, residing within a catchment area comprising eight ‘Super Output Areas’ in the Castle and St. James ward of Northampton. In April 2009, the Centre for Children and Youth (CCY) – a research centre based at The University of Northampton – was commissioned by Spring Lane Sure Start Children’s Centre to collate and gather evaluative data regarding experiences and perceptions of the Children’s Centre during its first year of activitie

    SMP: A solid modeling program version 2.0

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    The Solid Modeling Program (SMP) provides the capability to model complex solid objects through the composition of primitive geometric entities. In addition to the construction of solid models, SMP has extensive facilities for model editing, display, and analysis. The geometric model produced by the software system can be output in a format compatible with existing analysis programs such as PATRAN-G. The present version of the SMP software supports six primitives: boxes, cones, spheres, paraboloids, tori, and trusses. The details for creating each of the major primitive types is presented. The analysis capabilities of SMP, including interfaces to existing analysis programs, are discussed
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