703 research outputs found

    Spatial grouping determines temporal integration

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    To make sense out of a continuously changing visual world, people need to integrate features across space and time. Despite more than a century of research, the mechanisms of features integration are still a matter of debate. To examine how temporal and spatial integration interact, the authors measured the amount of temporal fusion (a measure of temporal integration) for different spatial layouts. They found that spatial grouping by proximity and similarity can completely block temporal integration. Computer simulations with a simple neural network capture these findings very well, suggesting that the proposed spatial grouping operations may occur already at an early stage of visual information processing

    Supporting decisions on conflicting land-uses: An integrated ecological-economic approach

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    An integrated ecological-economic decision-making approach is developed to help local stakeholders decide on land use in rural areas where the conflict between natural resource protection and economic development is pressing. It consists of four methodological steps. In the first step the political options and alternatives for action regarding changes in the land-use pattern are specified in order to derive politically relevant land-use strategies (scenarios). In the second step economic, ecological and social indicators are derived. The third step includes economic modelling (economic input-output model), environmental modelling (modelling of landscape water balance) and the qualitative and quantitative estimation of ecological and environmental effects. These efforts result in the production of a multi-indicator matrix. Finally, the fourth step deals with a combined monetary and multi-criteria evaluation resulting in a ranking of the land-use strategies. The discussion of the decision-making approach concentrates on the necessity of preliminary decisions and the possibility and necessity of stakeholders participation in the decisionmaking process. --evaluation,decision-making,multi-criteria analysis,land-use management,scenarios,benefit-cost analysis

    Feature fusion reveals slow and fast visual memories

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    Although the visual system can achieve a coarse classification of its inputs in a relatively short time, the synthesis of qualia-rich and detailed percepts can take substantially more time. If these prolonged computations were to take place in a retinotopic space, moving objects would generate extensive smear. However, under normal viewing conditions, moving objects appear relatively sharp and clear, suggesting that a substantial part of visual short-term memory takes place at a nonretinotopic locus. By using a retinotopic feature fusion and a nonretinotopic feature attribution paradigm, we provide evidence for a relatively fast retinotopic buffer and a substantially slower nonretinotopic memory. We present a simple model that can account for the dynamics of these complementary memory processes. Taken together, our results indicate that the visual system can accomplish temporal integration of information while avoiding smear by breaking off sensory memory into fast and slow components that are implemented in retinotopic and nonretinotopic loci, respectively

    Long lasting effects of unmasking in a feature fusion paradigm

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    In spite of more than 100years of research, the mechanisms underlying visual masking are still unknown. In recent publications, we introduced an unmasking paradigm involving the fusion of features that revealed interesting spatial characteristics. Here, we investigate the temporal aspects of this paradigm showing very long lasting effects that impose serious restrictions on models of masking. We used a simple feed-forward neural network model to explain these result

    Immunhistochemische Untersuchungen zur Herkunft der Solid-pseudopapillären Neoplasie des Pankreas

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    Mithilfe immunhistochemischer Färbemethoden sind Hinweise auf eine Herkunft der Solid-pseudopapillären Pankreasneoplasie (SPN) aus endokrinen Vorläuferzellen des Pankreas gefunden worden

    Homelessness and Incarceration: An Examination of Barriers to Misdemeanor Resolution for the Homeless

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    Abstract: The relationship between homelessness and crime has been investigated in few studies despite the implications of prior offenses and incarceration on job seekers. This study examined the relationship among homelessness, misdemeanors, incarceration, and misdemeanor resolution. Factors hindering misdemeanor resolution were explored by surveying participants at two Veterans Administration (VA) Stand Downs (n=186). The sample includes the primary service population of homeless veterans and other homeless persons. Respondents reported on factors perceived as limiting them from resolving misdemeanors, along with socio-demographic, homeless status, misdemeanor, and incarceration data. Factor Analysis yielded three factors as barriers that have implications for social work practice

    methBLAST and methPrimerDB: web-tools for PCR based methylation analysis

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    BACKGROUND: DNA methylation plays an important role in development and tumorigenesis by epigenetic modification and silencing of critical genes. The development of PCR-based methylation assays on bisulphite modified DNA heralded a breakthrough in speed and sensitivity for gene methylation analysis. Despite this technological advancement, these approaches require a cumbersome gene by gene primer design and experimental validation. Bisulphite DNA modification results in sequence alterations (all unmethylated cytosines are converted into uracils) and a general sequence complexity reduction as cytosines become underrepresented. Consequently, standard BLAST sequence homology searches cannot be applied to search for specific methylation primers. RESULTS: To address this problem we developed methBLAST, a sequence similarity search program, based on the original BLAST algorithm but querying in silico bisulphite modified genome sequences to evaluate oligonucleotide sequence similarities. Apart from the primer specificity analysis tool, we have also developed a public database termed methPrimerDB for the storage and retrieval of validated PCR based methylation assays. The web interface allows free public access to perform methBLAST searches or database queries and to submit user based information. Database records can be searched by gene symbol, nucleotide sequence, analytical method used, Entrez Gene or methPrimerDB identifier, and submitter's name. Each record contains a link to Entrez Gene and PubMed to retrieve additional information on the gene, its genomic context and the article in which the methylation assay was described. To assure and maintain data integrity and accuracy, the database is linked to other reference databases. Currently, the database contains primer records for the most popular PCR-based methylation analysis methods to study human, mouse and rat epigenetic modifications. methPrimerDB and methBLAST are available at and . CONCLUSION: We have developed two integrated and freely available web-tools for PCR based methylation analysis. methBLAST allows in silico assessment of primer specificity in PCR based methylation assays that can be stored in the methPrimerDB database, which provides a search portal for validated methylation assays
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