772 research outputs found

    Metastable Markov chains: from the convergence of the trace to the convergence of the finite-dimensional distributions

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    We consider continuous-time Markov chains which display a family of wells at the same depth. We provide sufficient conditions which entail the convergence of the finite-dimensional distributions of the order parameter to the ones of a finite state Markov chain. We also show that the state of the process can be represented as a time-dependent convex combination of metastable states, each of which is supported on one well

    Social familiarity modulates personality trait in a cichlid fish

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    Personality traits, such as exploration-avoidance, are expected to be adaptive in a given context (e.g. low-risk environment) but to be maladaptive in others (e.g. high-risk environment). Therefore, it is expected that personality traits are flexible and respond to environmental fluctuations, given that consistency across different contexts is maintained, so that the relative individual responses in relation to others remains the same (i.e. although the magnitude of the response varies the differences between high and low responders are kept). Here, we tested the response of male cichlid fish (Oreochromis mossambicus) to a novel object (NO) in three different social contexts: (i) social isolation, (ii) in the presence of an unfamiliar conspecific, and (iii) in the presence of a familiar conspecific. Males in the familiar treatment exhibited more exploratory behaviour and less neophobia than males in either the unfamiliar or the social isolation treatments. However, there were no overall correlations in individual behaviour across the three treatments, suggesting a lack of consistency in exploration-avoidance as measured by the NO test in this species. Moreover, there were no differences in cortisol responsiveness to an acute stressor between the three treatments. Together, these results illustrate how behavioural traits usually taken as measures of personality may exhibit significant flexibility and lack the expected consistency across different social contexts.info:eu-repo/semantics/publishedVersio

    False-positive HIV results and COVID-19 infection or vaccination?

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    Recently, there have been reports of false-positive HIV results associated with COVID-19 infections and vaccination, which require attention. The similarity between the spike proteins of HIV and SARS-CoV-2 may lead to cross-reactivity of antibodies, resulting in false-positive results on immunoassay screening tests. This hypothesis presents a serious diagnostic challenge. Patients presenting discordant COVID-19 and HIV results should undergo confirmation of the HIV chemiluminescent immunoassay due to the potential for analytical errors. It is essential to highlight the potential for false-positive HIV results related to SARS-CoV-2

    Computational Chemotaxis in Ants and Bacteria over Dynamic Environments

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    Chemotaxis can be defined as an innate behavioural response by an organism to a directional stimulus, in which bacteria, and other single-cell or multicellular organisms direct their movements according to certain chemicals in their environment. This is important for bacteria to find food (e.g., glucose) by swimming towards the highest concentration of food molecules, or to flee from poisons. Based on self-organized computational approaches and similar stigmergic concepts we derive a novel swarm intelligent algorithm. What strikes from these observations is that both eusocial insects as ant colonies and bacteria have similar natural mechanisms based on stigmergy in order to emerge coherent and sophisticated patterns of global collective behaviour. Keeping in mind the above characteristics we will present a simple model to tackle the collective adaptation of a social swarm based on real ant colony behaviors (SSA algorithm) for tracking extrema in dynamic environments and highly multimodal complex functions described in the well-know De Jong test suite. Later, for the purpose of comparison, a recent model of artificial bacterial foraging (BFOA algorithm) based on similar stigmergic features is described and analyzed. Final results indicate that the SSA collective intelligence is able to cope and quickly adapt to unforeseen situations even when over the same cooperative foraging period, the community is requested to deal with two different and contradictory purposes, while outperforming BFOA in adaptive speed. Results indicate that the present approach deals well in severe Dynamic Optimization problems.Comment: 8 pages, 6 figures, in CEC 07 - IEEE Congress on Evolutionary Computation, ISBN 1-4244-1340-0, pp. 1009-1017, Sep. 200

    Central Venous Catheter-Related Infection in Critically Ill Patients

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    Letter to the Edito

    Aptidão da bacia do Rio Dourados para o cultivo de eucalipto.

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    O objetivo desse trabalho foi a geração de mapas de aptidão florestal considerando níveis de manejo para Eucalyptus camaldulensis Dehn, Eucalyptus citriodora Hook, Eucalyptus grandis W Hill ex Maiden e Eucalyptus urophlla St. Blake na Bacia do Rio Dourados, com auxílio do software SPRING 4.1 (INPEbitstream/item/38727/1/BP200634.pdfDocumento on-line

    A moenda da azeitona e as características físico-químicas dos azeites virgens

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    Comunicação apresentada no III Simpósio Nacional de Olivicultura que decorreu em Castelo Branco na Escola Superior Agrária do Instituto Politécnico de Castelo Branco, de 29 a 31 de Outubro de 2003.No presente trabalho estudou-se a influência do tipo de moenda da azeitona nas características do azeite virgem, comparando os azeites obtidos extraídos por moinho de pedras e por moinho metálico de martelos (com grelhas 5 e 7 mm de diâmetro). A azeitona foi processada numa linha Rapanelli . A qualidade dos azeites foi avaliada por determinação de: acidez, índice de peróxido, absorvâncias no UV, composição em ácidos gordos, estabilidade oxidativa, K225, pigmentos clorofilinos, cor (L*a*b*) e polifenóis totais. Em geral, a moenda não influencia os parâmetros de qualidade dos azeites, dependendo mais das cultivares constituintes dos lotes. Os resultados mostram que quando se utilizam moinhos de martelos se obtêm azeites virgens com um teor superior de pigmentos clorofilinos

    Antioxidantes em azeites ‘Galega’ e ‘Azeiteira’ provenientes de frutos obtidos em duas épocas de colheita

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    No presente trabalho são determinados os biofenóis em azeites ‘Galega’ e ‘Azeiteira’ obtidos em duas épocas de colheita dos frutos e olivais em produção integrada. A separação da fracção fenólica foi feita por extracção líquido-líquido (ELL) e a análise dos compostos fenólicos obtida por cromatografia líquida de alta pressão (HPLC) com detecção por díodos (DAD). São também determinados: os tocoferóis por HPLC e fluorescência (FLD); os biofenóis totais por espectroscopia VIS; e a intensidade do sabor amargo (K225) por espectroscopia UV. Os azeites ‘Galega’ e ‘Azeiteira’ apresentam teores mais elevados de antioxidantes na colheita mais temporã indicando que – do ponto de vista nutricional, sensorial e da estabilidade deste alimento – não é benéfico retardar a época de colheita. O hidroxitirosol e a luteolina decrescem acentuadamente na segunda data de colheita para os azeites de cultivar ‘Azeiteira’. Os azeites ‘Galega’ apresentam teores mais elevados de α-tocoferol e ϒ-tocoferol
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