1,835 research outputs found

    Automatic landmarking for building biological shape models

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    We present a new method for automatic landmark extraction from the contours of biological specimens. Our ultimate goal is to enable automatic identification of biological specimens in photographs and drawings held in a database. We propose to use active appearance models for visual indexing of both photographs and drawings. Automatic landmark extraction will assist us in building the models. We describe the results of using our method on drawings and photographs of examples of diatoms, and present an active shape model built using automatically extracted data

    Level sets of functions and symmetry sets of smooth surface sections

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    We prove that the level sets of a real C^s function of two variables near a non-degenerate critical point are of class C^[s/2] and apply this to the study of planar sections of surfaces close to the singular section by the tangent plane at hyperbolic points or elliptic points, and in particular at umbilic points. We also analyse the cases coming from degenerate critical points, corresponding to elliptic cusps of Gauss on a surface, where the differentiability is now reduced to C^[s/4]. However in all our applications to symmetry sets of families of plane curves, we assume the C^infty smoothness.Comment: 15 pages, Latex, 6 grouped figures. The final version will appear in Mathematics of Surfaces. Lecture Notes in Computer Science (2005

    Protease inhibitor (Pi) locus, fertility and twinning

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    In a sample of 160 Dutch twin pairs and their parents, we found that mothers of dizygotic twins had frequencies of the S and Z alleles at the protease inhibitor (Pi) locus that were 3 times higher than a control sample. Mothers of identical twins also had a higher frequency of S than controls. The S allele may thus both increase ovulation rate and enhance the success of multiple pregnancies. There was also an increased frequency of the S allele in fathers of dizygotic twins; however, this may be a secondary effect of assortative mating for family size (indicating by the number of siblings of the parents), for which a correlation of 0.2 was observed. Parents of dizygotic twins came from larger families than parents of monozygotic twins, but no effect of Pi type on family size was seen. © 1992 Springer-Verlag

    Knock-on community impacts of a novel vector: spillover of emerging DWV-B from Varroa-infested honeybees to wild bumblebees.

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    This is the final version. Available from the publisher via the DOI in this record.The Sanger sequences that support the findings of this study have been deposited in GenBank with virus accession codes MG264907‐MG265503 and Nosema accession codes MK942707‐MK942712; SMRT reads have been archived in NCBI's Sequence Read Archive with BioProject accession number PRJNA542789. Prevalence and qPCR data that support the findings will be available from the Dryad Digital Repository: https://doi.org/10.5061/dryad.70jt240.Novel transmission routes can directly impact the evolutionary ecology of infectious diseases, with potentially dramatic effect on host populations and knock-on effects on the wider host community. The invasion of Varroa destructor, an ectoparasitic viral vector in Western honeybees, provides a unique opportunity to examine how a novel vector affects disease epidemiology in a host community. This specialist honeybee mite vectors deformed wing virus (DWV), an important re-emerging honeybee pathogen that also infects wild bumblebees. Comparing island honeybee and wild bumblebee populations with and without V. destructor, we show that V. destructor drives DWV prevalence and titre in honeybees and sympatric bumblebees. Viral genotypes are shared across hosts, with the potentially more virulent DWV-B overtaking DWV-A in prevalence in a current epidemic. This demonstrates disease emergence across a host community driven by the acquisition of a specialist novel transmission route in one host, with dramatic community level knock-on effects

    Pairwise Force SPH Model for Real-Time Multi-Interaction Applications

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    In this paper, we present a novel pairwise-force smoothed particle hydrodynamics (PF-SPH) model to allow modeling of various interactions at interfaces in real time. Realistic capture of interactions at interfaces is a challenging problem for SPH-based simulations, especially for scenarios involving multiple interactions at different interfaces. Our PF-SPH model can readily handle multiple kinds of interactions simultaneously in a single simulation; its basis is to use a larger support radius than that used in standard SPH. We adopt a novel anisotropic filtering term to further improve the performance of interaction forces. The proposed model is stable; furthermore, it avoids the particle clustering problem which commonly occurs at the free surface. We show how our model can be used to capture various interactions. We also consider the close connection between droplets and bubbles, and show how to animate bubbles rising in liquid as well as bubbles in air. Our method is versatile, physically plausible and easy-to-implement. Examples are provided to demonstrate the capabilities and effectiveness of our approach

    Aplicação de altas pressões em chouriço de peru sem aditivos - segurança alimentar

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    As tecnologias emergentes de conservação dos alimentos têm como objetivo a segurança microbiológica, preservando a qualidade nutricional e sensorial ao longo do armazenamento. As altas pressões hidrostáticas são um método de conservação, alternativo aos processos térmicos existentes mais agressivos. O objetivo deste trabalho foi avaliar a aplicação de altas pressões em chouriço de peru produzido sem adição de aditivos numa unidade fabril e submetido a altas pressões (600MPa durante 8 min). As amostras foram armazenadas a 4 °C. Analisadas no dia da aplicação do tratamento e após 2 e 4 meses. Os parâmetros microbiológicos, designadamente contagens de bactérias lácticas mesófilas, bolores e leveduras, bactérias coliformes, Clostridium perfringens, estafilococos coagulase positivos, Escherichia coli ß-glucuronidase positiva, mesófilos, psicrotróficos, e pesquisa de Listeria monocytogenes, e de Salmonella spp., foram analisados recorrendo às metodologias definidas segundo as normas internacionais. Na pesquisa de patogénicos todas as amostras analisadas apresentaram um resultado de ausência em 25 g de produto. As contagens de Escherichia coli, bolores e leveduras, bactérias coliformes, Clostridium perfringens, e estafilococos coagulase positivos revelaram-se inferiores a 10 UFC g-1. As amostras submetidas a altas pressões hidrostáticas obtiveram contagens de bactérias lácticas mesófilas, mesófilos e psicrotróficos inferiores às contagens das amostras sem tratamento, desde o dia da aplicação do tratamento, com uma redução de 2 log. Perante os resultados obtidos, o fabrico de chouriço de peru sem aditivos e com aplicação de altas pressões hidrostáticas surge como um método de conservação do produto.N/

    Efeito da aplicação de altas pressões em chouriço de frango sem aditivos

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    A procura de produtos com carne de aves e sem aditivos é cada vez mais acentuada por parte dos consumidores. As indústrias alimentares tentam corresponder a estas exigências com o desenvolvimento de produtos isentos de aditivos mas garantindo a segurança alimentar. As altas pressões são uma alternativa interessante face aos métodos tradicionais de conservação de alimentos, uma vez que permitem aumentar a segurança microbiológica. O objetivo deste trabalho foi estudar o efeito das altas pressões em chouriço de frango sem adição de aditivos, produzido numa unidade industrial. Após o tratamento (600MPa por 8 min) as amostras foram armazenadas a 4 °C. O controlo microbiológico foi realizado no dia 0, 2 e 4 meses de conservação. Efetuaram-se contagens de bactérias lácticas mesófilas, bolores e leveduras, bactérias coliformes, Clostridium perfringens, estafilococos coagulase positivos, Escherichia coli ß-glucuronidase positiva, mesófilos, e psicrotróficos, e pesquisas de Listeria monocytogenes, Salmonella spp., segundo as normas internacionais. Os resultados apontam a ausência de Salmonella spp. e de Listeria monocytogenes em 25 g de produto. As contagens de Escherichia coli, bolores e leveduras, bactérias coliformes, Clostridium perfringens, e estafilococos coagulase positivos foram inferiores a 10 UFC g-1 em todas as amostras. As análises microbiológicas revelaram que as amostras com tratamento obtiveram contagens de bactérias lácticas mesófilas, mesófilos e psicrotróficos inferiores às contagens das amostras sem tratamento, com uma redução de 2 log. Esta redução poderá estar associada ao efeito das altas pressões ao nível da estrutura e integridade funcional da membrana citoplasmática dos microrganismos. Em suma, as altas pressões são uma técnica de grande interesse na indústria alimentar.info:eu-repo/semantics/publishedVersio

    Bayesian approach and Naturalness in MSSM analyses for the LHC

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    The start of LHC has motivated an effort to determine the relative probability of the different regions of the MSSM parameter space, taking into account the present, theoretical and experimental, wisdom about the model. Since the present experimental data are not powerful enough to select a small region of the MSSM parameter space, the choice of a judicious prior probability for the parameters becomes most relevant. Previous studies have proposed theoretical priors that incorporate some (conventional) measure of the fine-tuning, to penalize unnatural possibilities. However, we show that such penalization arises from the Bayesian analysis itself (with no ad hoc assumptions), upon the marginalization of the mu-parameter. Furthermore the resulting effective prior contains precisely the Barbieri-Giudice measure, which is very satisfactory. On the other hand we carry on a rigorous treatment of the Yukawa couplings, showing in particular that the usual practice of taking the Yukawas "as required", approximately corresponds to taking logarithmically flat priors in the Yukawa couplings. Finally, we use an efficient set of variables to scan the MSSM parameter space, trading in particular B by tan beta, giving the effective prior in the new parameters. Beside the numerical results, we give accurate analytic expressions for the effective priors in all cases. Whatever experimental information one may use in the future, it is to be weighted by the Bayesian factors worked out here.Comment: LaTeX, 19 pages, 3 figure

    Can black holes be torn up by phantom dark energy in cyclic cosmology?

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    Infinitely cyclic cosmology is often frustrated by the black hole problem. It has been speculated that this obstacle in cyclic cosmology can be removed by taking into account a peculiar cyclic model derived from loop quantum cosmology or the braneworld scenario, in which phantom dark energy plays a crucial role. In this peculiar cyclic model, the mechanism of solving the black hole problem is through tearing up black holes by phantom. However, using the theory of fluid accretion onto black holes, we show in this paper that there exists another possibility: that black holes cannot be torn up by phantom in this cyclic model. We discussed this possibility and showed that the masses of black holes might first decrease and then increase, through phantom accretion onto black holes in the expanding stage of the cyclic universe.Comment: 6 pages, 2 figures; discussions adde
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