501 research outputs found

    Modelling O2 and CO2 exchange for development of perforation mediated modifed atmosphere packaging

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    Perforation-mediated modi®ed atmosphere packaging relies on the use of macro perforations or tubes to control the O2 and CO2 exchange and create the desired atmosphere inside an otherwise gas-tight package. In this work, the O2 and CO2 exchange through a single tube was studied. Di erent temperatures (5±20°C) and tube dimensions (length from 9 to 17 mm and diameter from 6 to 30 mm) were tested. O2 and CO2 mass transfer coe cients were determined according to a lumped mass transfer capacitance model that yielded a good description of the gas transfer. Temperature in the range tested did not show a signi®cant e ect on the mass transfer coe cients. A multiplicative non-linear equation was found to yield a good prediction of the dependence of the O2 mass transfer coe cient on tube diameter and length. The ratio between the CO2 and O2 mass transfer coe cients, an important parameter in the design of MAP, was 0.81 and none of the factors tested in¯uenced its value

    Probabilistic Reuse of Past Search Results

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    International audienceIn this paper, a new Monte Carlo algorithm to improve precision of information retrieval by using past search results is presented. Experiments were carried out to compare the proposed algorithm with traditional retrieval on a simulated dataset. In this dataset, documents, queries, and judgments of users were simulated. Exponential and Zipf distributions were used to build document collections. Uniform distribution was applied to build the queries. Zeta distribution was utilized to simulate the Bradford’s law representing the judgments of users. Empirical results show a better performance of our algorithm compared with traditional retrieval

    O Sistema Endocanabinóide – uma perspetiva terapêutica

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    Although the medicinal use of Cannabis sativa derivatives is well known since antiquity, the study of their properties expanded recently with the discovery of an endogenous cannabinoid system, which comprises the endogenous cannabis-like ligands (endocannabinoids), the cannabinoid receptors (CB1 and CB2) and the enzymes involved in their metabolism. Since the discovery of the endocannabinoid system (ECS), the scientific community focused on research of its clinical use and achieved important findings during the last decade. In some countries, cannabis derivatives are a pharmacological option for appetite stimulation and pain treatment. However, the first ECS-based drug rimonabant (a CB1 antagonist), approved for the treatment obesity with associated risk factors, was withdrawn due to safety concerns. Nowadays, based on the growing evidences resulting from preclinical and clinical studies of ECS modulators, these drugs are currently pointed out as novel therapeutic approaches for several pathophysiological conditions. Here, we review the potential role of (endo)cannabinoid system in therapeutics and the recent designed strategies for the development of drugs that target this system. A utilização terapêutica da Cannabis sativa ou seus derivados é conhecida há muitos anos, no entanto, o estudo das suas propriedades despontou recentemente com a descoberta de um sistema canabinóide endógeno (ECS). O ECS compreende os compostos endógenos similares ao tetrahidrocanabinol (endocanabinóides), os recetores canabinóides (CB1 e CB2) e as enzimas envolvidas no seu metabolismo. Desde a descoberta do ECS, a comunidade científica focou-se na investigação do seu potencial clínico com resultados encorajadores. Em alguns países, os derivados da cannabis constituem uma opção farmacológica na estimulação do apetite e tratamento da dor. O primeiro medicamento baseado no ECS, o rimonabant (um antagonista CB1), foi aprovado para o tratamento da obesidade associada a outros fatores de risco, no entanto foi retirado por questões de segurança. Atualmente, e baseadas nos estudos pré-clínicos e clínicos, existem várias evidências do seu interesse clínico na modulação de diversas condições fisiopatológicas. Neste artigo discutimos o papel potencial do sistema (endo)canabinóide na terapêutica e as recentes estratégias desenvolvidas na modulação do sistema.

    Moving towards adaptive search in digital libraries

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    Search applications have become very popular over the last two decades, one of the main drivers being the advent of the Web. Nevertheless, searching on the Web is very different to searching on smaller, often more structured collections such as digital libraries, local Web sites, and intranets. One way of helping the searcher locating the right information for a specific information need in such a collection is by providing well-structured domain knowledge to assist query modification and navigation. There are two main challenges which we will both address in this chapter: acquiring the domain knowledge and adapting it automatically to the specific interests of the user community. We will outline how in digital libraries a domain model can automatically be acquired using search engine query logs and how it can be continuously updated using methods resembling ant colony behaviour. © 2011 Springer-Verlag

    Probabilistic Reuse of Past Search Results

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    In this paper, a new Monte Carlo algorithm to improve precision of information retrieval by using past search results is presented. Experiments were carried out to compare the proposed algorithm with traditional retrieval on a simulated dataset. In this dataset, documents, queries, and judgments of users were simulated. Exponential and Zipf distributions were used to build document collections. Uniform distribution was applied to build the queries. Zeta distribution was utilized to simulate the Bradford’s law representing the judgments of users. Empirical results show a better performance of our algorithm compared with traditional retrieval
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