3,031 research outputs found

    Morphological and molecular determination of Fucus (Fucales, Heterokontophyta) biogeography across North American shores

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    The genus Fucus (Phaeophyceae) has nine commonly accepted species, six of which inhabit North American shores: F. gardneri, F. serratus, F. distichus, F. evanescens, F. vesiculosus, and F. spiralis. Fucus inhabit the intertidal zones of the Atlantic, Pacific and Arctic Oceans and due to their highly plastic and morphologically simple phenotypes, are valuable candidates for molecular phylogenetic research. Furthermore, Fucus species are valuable for biogeographic investigations due to their relatively slow migration, limited dispersal range, and easily collected distribution. The closest ancestral species to the genus is a Pacific endemic Hesperophycus californicus supporting a North Pacific origin of the species (Serrão et al. 1999). However, a closer relationship between Atlantic and Arctic Fucus has been described casting doubt on the Pacific origins of the genus (Lindstrom 2001, Dunton 1992). The investigation of Fucus across this area is necessary to elucidate the apparent contradiction in the origin of the genus. Samples were collected from 79 locations across North American waters. The amplification of the divergent mtDNA spacer region was performed to assess taxonomic placement of 55 collected species and reconstruct the biogeography of North American Fucus species. Morphological analysis was also completed based on 21 measured characteristics in an attempt to support molecular analysis. Results of the study indicate two distinct lineages among collected samples. One lineage (F. spiralis and F. vesiculosus) with a distinct Atlantic origin and the second lineage (F. distichus and F. serratus) with a widely distributed F. distichus, and the Atlantic F. serratus. Morphological analysis and statistical support for these lineages was determined through discriminant analysis of the collected samples. Overall results determined biogeographic influences in the F. distichus species complex across Arctic, Pacific, and Atlantic regions with little apparent biogeographical influence within F. vesiculosus, F. serratus and F. spiralis. Closer phylogenetic relationships between Arctic and Atlantic samples were apparent as suggested by Lindstrom (2001) and Dunton (1992)

    Methods for the capture of manufacture best practice in product lifecycle management

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    The capture of manufacturing best practice knowledge in product lifecycle management systems has significant potential to improve the quality of design decisions and minimise manufacturing problems during new product development. However, providing a reusable source of manufacturing best practice is difficult due to the complexity of the viewpoint relationships between products and the manufacturing processes and resources used to produce them. This paper discusses how best to organise manufacturing best practice knowledge, the relationships between elements of this knowledge plus their relationship to product information. The paper also explores the application of UML-2 as a system design tool which can model these relationships and hence support the reuse of system design models over time. The paper identifies a set of part family and feature libraries and, most significantly, the relationships between them, as a means of capturing best practice manufacturing knowledge and illustrates how these can be linked to manufacturing resource models and product information. Design for manufacture and machining best practice views are used in the paper to illustrate the concepts developed. An experimental knowledge based system has been developed and results generated using a power transmission shaft example

    Solid Waste Management (SWM) Options: The Economics of Variable Cost and Conventional Pricing Systems in Maine

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    Solid waste management has been influenced by the growing trend to apply market-based incentives to environmental problems. The impetus to reform solid waste management procedures in part stems from the increasing costs associated with solid waste disposal, thus encouraging municipalities to seek innovative ways to reduce solid waste generation. One method adopted by numerous municipalities in Maine is known as variable cost pricing. Alternatively, this system is referred to as unit pricing, volume-based fees, and pay-by-the-bag (PB). Under this system, waste collection fees are based on the volume of solid waste disposal. A household\u27s solid waste disposal costs change with the number of bags of waste disposed since each bag is assessed a fee. As a result, the less trash set out for disposal, the lower the cost to the resident

    Job Satisfaction of Female and Male Superintendents: The Influence of Job Facets and Contextual Variables as Potential Predictors

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    A descriptive multiple regression approach was used to assess the job satisfaction of female and male public school superintendents taking part in a decennial survey conducted by AASA. Self-reported job satisfaction of public school superintendents was regressed on their affective reactions to specific job facets (supervision, co-workers, and compensation) and to contextual variables (type of school district, legislative mandates, and funding sources) purported to influence their job satisfaction. Results indicate that female and male superintendents were found to be similarly satisfied with their current job assignment but for different reasons as revealed by interaction terms addressed in the regression analyses

    Systematic design of legal regulations for optimal surface-groundwater usage - Phase 2

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    Includes bibliographical references.September 1975.To view the abstract, please see the full text of the document.OWRT Project no. B-109-Co1orado, Period July 1, 1973 - September 30, 1975; partly funded by U.S. Office of Water Resources Research, project no. B-076-Colorado, agreement no.14-31-0001-3866

    Monomeric ephrinB2 binding induces allosteric changes in Nipah virus G that precede its full activation.

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    Nipah virus is an emergent paramyxovirus that causes deadly encephalitis and respiratory infections in humans. Two glycoproteins coordinate the infection of host cells, an attachment protein (G), which binds to cell surface receptors, and a fusion (F) protein, which carries out the process of virus-cell membrane fusion. The G protein binds to ephrin B2/3 receptors, inducing G conformational changes that trigger F protein refolding. Using an optical approach based on second harmonic generation, we show that monomeric and dimeric receptors activate distinct conformational changes in G. The monomeric receptor-induced changes are not detected by conformation-sensitive monoclonal antibodies or through electron microscopy analysis of G:ephrinB2 complexes. However, hydrogen/deuterium exchange experiments confirm the second harmonic generation observations and reveal allosteric changes in the G receptor binding and F-activating stalk domains, providing insights into the pathway of receptor-activated virus entry.Nipah virus causes encephalitis in humans. Here the authors use a multidisciplinary approach to study the binding of the viral attachment protein G to its host receptor ephrinB2 and show that monomeric and dimeric receptors activate distinct conformational changes in G and discuss implications for receptor-activated virus entry

    Manufacturing knowledge sharing in PLM: a progression towards the use of heavy weight ontologies

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    The drive to maximize the potential benefits of decision support systems continues to increase as industry is continually driven by the competitive needs of operating in dynamic global environments. The more extensive information support tools which are becoming available in the PLM world appear to have great potential but require a substantial overhead in their configuration. However, sharing information and knowledge in cross-disciplinary teams and across system and company boundaries is not straightforward and there is a clear need for more effective frameworks for information and knowledge sharing if new product development processes are to have effective ICT support. This paper presents a view of the current status of manufacturing information sharing using light-weight ontologies and goes on to discuss the potential for heavyweight ontological engineering approaches such as the Process Specification Language (PSL). It explains why such languages are needed and how they provide an important step towards process knowledge sharing. Machining examples are used to illustrate how PSL provides a rigorous basis for process knowledge sharing and subsequently to illustrate the value of linking foundation and domain ontologies to provide a basis for multi-context knowledge sharing

    Enabling interoperable manufacturing knowledge sharing in PLM

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    Traditional approaches to integrated information sharing fall far short of meeting the requirements for the seamless sharing of knowledge to support enterprise activities through the product lifecycle. Recent advances in ontological approaches to manufacturing knowledge organisation is showing promise that a step change in knowledge sharing capability can be achieved from the application of rigorous logic based languages, combined with methods for modelling context relationships. This paper discusses the issues involved in providing an interoperable manufacturing knowledge sharing environment and proposes a manufacturing foundation ontology as a key requirement for interoperable manufacturing knowledge sharing
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