1,907 research outputs found

    Classical symmetric functions in superspace

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    We present the basic elements of a generalization of symmetric function theory involving functions of commuting and anticommuting (Grassmannian) variables. These new functions, called symmetric functions in superspace, are invariant under the diagonal action of the symmetric group on the sets of commuting and anticommuting variables. In this work, we present the superspace extension of the classical bases, namely, the monomial symmetric functions, the elementary symmetric functions, the completely symmetric functions, and the power sums. Various basic results, such as the generating functions for the multiplicative bases, Cauchy formulas, involution operations as well as the combinatorial scalar product are also generalized.Comment: 21 pages, this supersedes the first part of math.CO/041230

    Migrating medical communications software to a multi-tenant cloud environment

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    The rise of cloud computing has paved the way for many new applications. Many of these new cloud applications are also multi-tenant, ensuring multiple end users can make use of the same application instance. While these technologies make it possible to create many new applications, many legacy applications can also benefit from the added flexibility and cost-savings of cloud computing and multi-tenancy. In this paper, we describe the steps required to migrate a. NET-based medical communications application to the Windows Azure public cloud environment, and the steps required to add multi-tenancy to the application. We then discuss the advantages and disadvantages of our migration approach. We found that the migration to the cloud itself requires only a limited amount of changes to the application, but that this also limited the benefits, as individual instances would only be partially used. Adding multi-tenancy requires more changes, but when this is done, it has the potential to greatly reduce the cost of running the application

    Implications of movement for species distribution models - rethinking environmental data tools

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    Movement is considered an essential process in shaping the distributions of species. Nevertheless, most species distribution models (SDMs) still focus solely on environment-species relationships to predict the occurrence of species. Furthermore, the currently used indirect estimates of movement allow to assess habitat accessibility, but do not provide an accurate description of movement. Better proxies of movement are needed to assess the dispersal potential of individual species and to gain a more practical insight in the interconnectivity of communities. Telemetry techniques are rapidly evolving and highly capable to provide explicit descriptions of movement, but their usefulness for SDMs will mainly depend on the ability of these models to deal with hitherto unconsidered ecological processes. More specifically, the integration of movement is likely to affect the environmental data requirements as the connection between environmental and biological data is crucial to provide reliable results. Mobility implies the occupancy of a continuum of space, hence an adequate representation of both geographical and environmental space is paramount to study mobile species distributions. In this context, environmental models, remote sensing techniques and animal-borne environmental sensors are discussed as potential techniques to obtain suitable environmental data. In order to provide an in-depth review of the aforementioned methods, we have chosen to use the modelling of fish distributions as a case study. The high mobility of fish and the often highly variable nature of the aquatic environment generally complicate model development, making it an adequate subject for research. Furthermore, insight into the distribution of fish is of great interest for fish stock assessments and water management worldwide, underlining its practical relevance

    Automatic Sentiment Analysis in On-line Text

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    The growing stream of content placed on the Web provides a huge collection of textual resources. People share their experiences on-line, ventilate their opinions (and frustrations), or simply talk just about anything. The large amount of available data creates opportunities for automatic mining and analysis. The information we are interested in this paper, is how people feel about certain topics. We consider it as a classification task: their feelings can be positive, negative or neutral. A sentiment isn't always stated in a clear way in the text; it is often represented in subtle, complex ways. Besides direct expression of the user's feelings towards a certain topic, he or she can use a diverse range of other techniques to express his or her emotions. On top of that, authors may mix objective and subjective information about a topic, or write down thoughts about other topics than the one we are investigating. Lastly, the data gathered from the World Wide Web often contains a lot of noise. All of this makes the task of automatic recognition of the sentiment in on-line text more difficult. We will give an overview of various techniques used to tackle the problems in the domain of sentiment analysis, and add some of our own results

    Estuarine behaviour of European silver eel (<i>Anguilla anguilla</i>) in the Scheldt estuary

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    Estuaries are among the most productive ecosystems in the world and are characterised by high habitat diversity. As transition areas between inland rivers and the open sea, they function as transport zones for diadromous species like the European eel (Anguilla anguilla), a catadromous fish species that migrates to the Sargasso Sea for spawning. However, information on the migratory behaviour of eel in estuaries is scarce. Therefore, more insight is needed to efficiently restore and conserve the species. We tracked 47 eels with acoustic telemetry between July 2012 and October 2015 and analysed their behaviour from the Braakman creek into the Scheldt Estuary, separated by a tidal barrier. Eels arrived in the Braakman between mid-summer and early winter and stayed there on average 44 days (0 - 578 days). As such, arrival in the Scheldt Estuary was much later: between early autumn and early winter. The average residence time in the Scheldt Estuary was considerably shorter than in the Braakman, and was only five days (0 - 64 days). The long residence time in the Braakman was probably due to the discontinuous operation of the tidal barrier, which is used to control the water level in the upstream wetland area. This resulted in a discontinuous flow conditions, leading to searching behaviour in eels. Eventually 37 eels did pass the sluice and reached the Scheldt Estuary; the 10 eels which did not pass the sluice were probably caught by a commercial eel fisherman in the Braakman creek. In the Scheldt Estuary, 26 eels migrated towards the sea, whereas eight took the opposite direction and three were only detected at the first receivers downstream of the sluice. The eight eels that did not migrate towards the sea showed estuarine retention behaviour. They could have been injured by the tidal barrier or missed the right moment to migrate, and could be waiting in the estuary until favourable conditions are met to proceed their journey. Our results indicate that eel migration is obstructed by a tidal barrier, which resulted in delayed eel migration. As the migratory period occurred from mid-summer to early winter, this information can be implemented in management plans such as environmental windows to open the sluice during eel migration if circumstances allow such measurements

    Anthelmintic tolerance in free-living and facultative parasitic isolates of Halicephalobus (Panagrolaimidae)

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    Studies on anthelmintic resistance in equine parasites do not include facultative parasites. Halicephalobus gingivalis is a free-living bacteriovorous nematode and a known facultative parasite of horses with a strong indication of some form of tolerance to common anthelmintic drugs. This research presents the results of an in vitro study on the anthelmintic tolerance of several isolates of Halicephalobus to thiabendazole and ivermectin using an adaptation of the Micro-Agar Larval Development Test hereby focusing on egg hatching and larval development. Panagrellus redivivus and Panagrolaimus superbus were included as a positive control. The results generally show that the anthelmintic tolerance of Halicephalobus to both thiabendazole and ivermectin was considerably higher than that of the closely related Panagrolaimidae and, comparing to other studies, than that of obligatory equine parasites. Our results further reveal a remarkable trend of increasing tolerance from fully free-living isolates towards horse-associated isolates. In vitro anthelmintic testing with free-living and facultative parasitic nematodes offers the advantage of observing drug effect on the complete lifecycle as opposed to obligatory parasites which can only be followed until the third larval stage. We therefore propose Halicephalobus gingivalis as an experimental tool to deepen our understanding of the biology of anthelmintic tolerance

    Resource utilization and trophic position of nematodes and harpacticoid copepods in and adjacent to Zostera noltii beds

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    This study examines the resource use and trophic position of nematodes and harpacticoid copepods at the genus/species level in an estuarine food web in Zostera noltii beds and in adjacent bare sediments using the natural abundance of stable carbon and nitrogen isotopes. Microphytobenthos and/or epiphytes are among the main resources of most taxa, but seagrass detritus and sediment particulate organic matter contribute as well to meiobenthos nutrition, which are also available in deeper sediment layers and in unvegetated patches close to seagrass beds. A predominant dependence on chemoautotrophic bacteria was demonstrated for the nematode genus Terschellingia and the copepod family Cletodidae. A predatory feeding mode is illustrated for Paracomesoma and other Comesomatidae, which were previously considered first-level consumers (deposit feeders) according to their buccal morphology. The considerable variation found in both resource use and trophic level among nematode genera from the same feeding type, and even among congeneric nematode species, shows that the interpretation of nematode feeding ecology based purely on mouth morphology should be avoided
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