940 resultados para creating environments for interaction


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BACKGROUND: The magnitude of risk conferred by the interaction between tobacco and alcohol use on the risk of head and neck cancers is not clear because studies have used various methods to quantify the excess head and neck cancer burden. METHODS: We analyzed individual-level pooled data from 17 European and American case-control studies (11,221 cases and 16,168 controls) participating in the International Head and Neck Cancer Epidemiology consortium. We estimated the multiplicative interaction parameter (psi) and population attributable risks (PAR). RESULTS: A greater than multiplicative joint effect between ever tobacco and alcohol use was observed for head and neck cancer risk (psi = 2.15; 95% confidence interval, 1.53-3.04). The PAR for tobacco or alcohol was 72% (95% confidence interval, 61-79%) for head and neck cancer, of which 4% was due to alcohol alone, 33% was due to tobacco alone, and 35% was due to tobacco and alcohol combined. The total PAR differed by subsite (64% for oral cavity cancer, 72% for pharyngeal cancer, 89% for laryngeal cancer), by sex (74% for men, 57% for women), by age (33% for cases <45 years, 73% for cases >60 years), and by region (84% in Europe, 51% in North America, 83% in Latin America). CONCLUSIONS: Our results confirm that the joint effect between tobacco and alcohol use is greater than multiplicative on head and neck cancer risk. However, a substantial proportion of head and neck cancers cannot be attributed to tobacco or alcohol use, particularly for oral cavity cancer and for head and neck cancer among women and among young-onset cases.

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The Rebuild Iowa Infrastructure Investment Bonds are exactly that: an investment in Iowa and Iowans. Proposed by Governor Chet Culver in his 2009 Condition of the State address, the Rebuild Iowa bonds are an investment of $700 million to create jobs by addressing much-needed infrastructure projects across the state.

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We consider an agent who has to repeatedly make choices in an uncertainand changing environment, who has full information of the past, who discountsfuture payoffs, but who has no prior. We provide a learning algorithm thatperforms almost as well as the best of a given finite number of experts orbenchmark strategies and does so at any point in time, provided the agentis sufficiently patient. The key is to find the appropriate degree of forgettingdistant past. Standard learning algorithms that treat recent and distant pastequally do not have the sequential epsilon optimality property.

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Interaction between Musca domestica L. and its predator Muscina stabulans (Fallén) (Diptera, Muscidae): Effects of prey density and food source abundance. The objective of this work was to evaluate the influence of prey density and food source abundance on the predatory behavior of Muscina stabulans over M. domestica. Three predator/prey proportions were evaluated (1:1, 1:3 and 1:6), using 100 third instar predator larvae against second instar prey larvae. Each proportion was maintained using three different levels of food substrate (25, 50 and 100 g). The experiments were carried out in triplicate in BOD incubators (25ºC, UR 70% ± 10% and 12 h photoperiod). The mortality of the M. domestica larvae was 100% under all conditions, except in the 1:6 predator/prey proportion, at the 50g and 100g food substrate levels, where it was 99.99% and 99.22%, respectively. There was a significant increase in the development period of M. stabulans in relation to the increase in prey density and decrease in quantity of food substrate. An increase in the proportion of individuals and a reduction in the amount of resource slowed down larval development. Muscina stabulans pupal weight was proportional to the increase in prey density and the amount of food substrate. The proportion or the density influenced the survival of M. stabulans, with no difference in relation to the amount of food source and consequently in the interaction of the factors. There was no difference between the 1:1 and 1:3 predator-prey densities, with both differing from the 1:6 density.

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Carabid beetle assemblages in three environments in the Araucaria humid forest of southern Brazil. Carabidae is composed mainly by ground-dwelling predator beetles. It is the fourth most diverse group within Coleoptera, but its diversity in the Neotropical region is understudied. Here we describe and analyze the diversity of carabid beetles in a region of subtropical rain forest dominated by Araucaria angustifolia with different landscapes. Three areas were chosen in an environmental integrity gradient: primary forests, secondary forests and old Pinus plantations. Pitfall traps were taken monthly, in a total of 14 samples per area. 1733 adult carabid beetles, belonging to 18 species, were sampled. There were differences in richness and abundance between the sampled areas. The total scores followed the same tendency: primary forests (14 species/747 individuals), secondary forests (13/631) and Pinus forests (10/355). An analysis of similarity shows differences in species composition, for both areas and seasons. Galerita lacordarei was the most abundant species for all samples and seasons. Carabid species show similar responses in accordance with habitat heterogeneity and disturbance. The abundance of Galerita lacordarei was influenced by temperature, for all sampled sites. Environmental changes affect the carabid assemblages and decrease diversity, possibly interfering in local dynamics. Seasonality patterns seem to indicate an increase in individual movement during summer, probably in search of resources. It is suggested that microhabitat patchiness is probably an important factor affecting carabid beetle diversity at small spatial scales.

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Abstract: Microbial mats very efficiently cycle elements, such as C, 0, N, S and H, which makes them key players of redox processes at the biosphere-lithosphere interface. They are characterized by high metabolic activities and high turnover rates (production and consumption) of biomass, which mainly consists of cell material and of extracellular organic matter (EOM). The EOM forms a matrix, embedding the microbial cells and fulfilling various functions within the microbial mat, including: mat attachment to surfaces; creation of micro-domains within the mat; physical stabilization under hy- drodynamic stress and the protection of the cells in multiple other stress conditions. EOM mainly consists of polysaccharides, amino acids, and a variety of chemical func-tional groups {e.g., -C00H, - SH -OH). These groups strongly bind cations such as Ca2+ and Mg2+ and thus exert a strong control on carbonate mineral formation within the microbial mat. A feedback mechanism between community metabolisms, their prod¬ucts, and the surrounding physicochemical microenvironment thus influences the de¬gree of carbonate saturation favoring either carbonate precipitation or dissolution. We investigated the driving forces and mechanisms of microbialite formation in the Sari ne River, FR, Switzerland, the hypersaline lake, Big Pond, Bahamas and in labo¬ratory experiments. The two fundamentally different natural systems allowed us to compare the geochemical conditions and microbial metabolisms, necessary for car¬bonate formation in microbial mats. Although carbonates are oversaturated in both environments, precipitation does not occur on physicochemical substrates (i.e. out¬side the microbial mats). In the Sarine a high crystal nucleation threshold exceeds the carbonate saturation, despite the high carbonate alkalinity in the water column. Cyanobacterial photosynthesis strongly locally enhances the carbonate alkalinity, whereas the EOM attract and immobilize calcium, which increases the saturation state and finally leads to carbonate precipitation within the EOM (in this case the cyanobacterial sheath) as nucleation template. In Big Pond, the presence of calcium- chelating anions (i.e. sulfate) and EOM, as well as the presence of magnesium, lowers the calcium activity in the water column and mat, and thus inhibits carbonate pre¬cipitation. Coupled with other heterotrophic metabolisms, sulfate reduction uses the EOM as carbon source, degrading it. The resulting EOM consumption creates alkalin¬ity, releases calcium and consumes sulfate in mat-micro domains, which leads to the formation of carbonate layers at the top of the microbial mat. Résumé: Interface biosphère/lithosphère: médiation microbienne de la précipitation de CaC03 dans des environnements en eaux douces et hypersalines Les tapis microbiens engendrent une circulation très efficace des éléments, tels que C, 0, N, S et H, ce qui en fait des acteurs clé pour les processus d'oxydoréduction à l'inter¬face biosphère-lithosphère. Ils sont caractérisés par des taux élevés d'activité méta¬bolique, ainsi que par la production et la consommation de biomasse, principalement constituée de cellules microbiennes et de matière organique extracellulaire (MOE). Dans un tapis microbien, les cellules microbiennes sont enveloppées par une matrice de MOE qui a différentes fonctions dont l'attachement du tapis aux surfaces, la créa¬tion de micro-domaines dans le tapis, la stabilisation physique en situation de stress hydrodynamique, et la protection des cellules dans de multiples autres conditions de stress. La MOE se compose principalement de polysaccharides, d'acides aminés, et d'une variété de groupes fonctionnels chimiques (par exemple, COOH, -SH et -OH). Ces groupes se lient fortement aux cations, tels que Ca2+ et Mg2+, et exercent ainsi un contrôle fort sur la formation de CaC03 dans le tapis microbien. Un mécanisme de rétroaction, entre les métabolismes de la communauté microbienne, leurs produits, et le microenvironnement physico-chimique, influence le degré de saturation de car¬bonate, favorisant soit leur précipitation, soit leur dissolution. Nous avons étudié le moteur et les mécanismes de minéralisation dans des tapis de la Sarine, FR, Suisse et du lac hypersalin, Big Pond, aux Bahamas, ainsi que durant des expériences en laboratoire. Les deux systèmes naturels, fondamentalement dif¬férents, nous ont permis de comparer les conditions géochimiques et les métabolis¬mes nécessaires à la formation des carbonates dans des tapis microbiens. Bien que les carbonates soient sursaturés dans les deux environnements, la précipitation ne se produit pas sur des substrats physico-chimiques (en dehors du tapis microbien). Dans la Sarine, malgré un taux d'alcalinité élevé, les valeurs de seuil pour la nucléa- tion de carbonates sont plus hautes que la saturation du carbonate. La photosynthèse cyanobactérienne augmente localement l'alcalinité, alors que la MOE attire et immo¬bilise le calcium, ce qui augmente l'état de saturation et conduit finalement à la pré¬cipitation des carbonates, en utilisant la MOE comme substrat de nucléation. À Big Pond, la présence de chélateurs de calcium, notamment les anions (p.ex. le sulfate) et la MOE, ainsi que la présence de magnésium, réduit l'activité du calcium et inhibe en conséquence la précipitation des carbonates. Couplée avec d'autres métabolismes hétérotrophes, la réduction des sulfates utilise la MOE comme source de carbone, en la dégradant. Cette consommation de MOE crée l'alcalinité, consomme des sulfates et libère du calcium dans des micro-domaines, conduisant à la formation de couches de carbonates dans le haut du tapis microbien.

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Twenty species of Tephritidae (Diptera) are recorded in association with capitula of plants in the family Asteraceae. The Tephritidae genus Tetreuarestais registered for Rio Grande do Sul for the first time. Five species of Tephritidae are newly recorded for Rio Grande do Sul, and new hosts are recorded for the following fly species: Dioxyna chilensis (Macquart), Plaumannimyia dolores (Hering), Plaumannimyia imitatrix (Hering), Plaumannimyia miseta(Hering), Plaumannimyia pallensHering, Tomoplagia incompleta (Williston), Tomoplagia matzenbacheriPrado, Norrbom & Lewinsohn, Tomoplagia reimoseriHendel, Xanthaciura biocellata(Thomson) and Xanthaciura chrysura(Thomson).

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This work describes the characteristics of a representative set of seven different virtual laboratories (VLs) aimed for science teaching in secondary school. For this purpose, a 27-item evaluation model that facilitates the characterization of the VLs was prepared. The model takes into account the gaming features, the overall usability, and also the potential to induce scientific literacy. Five of the seven VLs were then tested with two larger and highly heterogenic groups of students, and in two different contexts – biotechnology and physics, respectively. It is described how the VLs were received by the students, taking into account both their motivation and their self-reported learning outcome. In some cases, students’ approach to work with the VLs was recorded digitally, and analyzed qualitatively. In general, the students enjoyed the VL activities, and claimed that they learned from them. Yet, more investigation is required to address the effectiveness of these tools for significant learning.

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Doctoral dissertation, University of Turku

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The tubero-infundibular and nigrostriatal DA neurone systems of rats respond to systemic (i.p.) injection of alpha-MSH (2-100 microgram/kg). The response of the tubero-infundibular (arcuate) DA neurones, an increase in cellular fluorescence intensity which can be interpreted as a sign of increased neuronal activity, is essentially the same in males, estrogen-progesterone-pretreated ovariectomized females and hypophysectomized males, whereas the type of response elicited by alpha-MSH in the nigral DA neurones depends upon the hormonal state of the animal. Differences between the two DA neurone groups exist also with regard to the effects of peptide fragments containing the two active sites of the alpha-MSH molecule. Results of lesion experiments in the lower brainstem (area postrema) and of blockade of muscarinic mechanisms by atropine further point to differences in the mechanisms underlying the peptide effects on the two neurone systems. The reaction of the tubero-infundibular DA system (which controls the pars intermedia of the pituitary) can be considered to reflect the activation of a feedback mechanism on MSH secretion, while the functional counterpart of the changes observed in the nigral system remains unknown at the present time.

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Pour que deux protagonistes parviennent à communiquer, ils doivent non seulement partager les signes verbaux et/ou non verbaux qu'ils utilisent, mais ils doivent également parvenir à accéder à l'intention communicative de chacun. Ce dernier aspect de la communication a été intimement lié aux significations et aux connaissances que les protagonistes partagent (angl. common ground). Malgré le fait que l'importance des significations partagées ait été soulignée dans la littérature concernant la communication entre adultes, cet aspect n'a pas été étudié en ce qui concerne le développement précoce de la communication. Dans le présent travail, nous suggérons d'investiguer le lien entre les significations partagées entre le jeune enfant et l'adulte et la capacité de l'enfant à communiquer de manière intentionnelle via des gestes. En nous appuyant sur l'approche de la Pragmatique de l'Objet (Moro & Rodríguez, 2005), nous suggérons que les connaissances concernant l'usage culturel de l'objet que construit progressivement l'enfant représentent un type de significations que l'enfant partage avec autrui. 12 dyades mère-enfant ont été enregistrées à l'aide d'une caméra lors d'interactions avec quatre objets. Les observations ont eu lieu au domicile des familles et ont été conduites chaque deuxième mois lorsque les enfants ont été âgés de 8 à 16 mois (groupe 1) et de 16 à 24 mois (groupe 2). Les observations ont été codées pour le niveau de maîtrise de l'usage culturel par l'enfant ainsi que pour la production de gestes par l'enfant et par l'adulte. Nous avons trouvé que plus l'enfant maîtrise les usages culturels des objets, plus il produit de gestes, et plus ces gestes remplissent une fonction communicative explicite. Concernant les gestes de l'adulte, les résultats dévoilent que plus l'enfant maîtrise les usages conventionnels des objets, plus l'adulte adresse des gestes communicatifs à l'enfant, plus ses gestes sont produits de manière complexe et plus l'intention des gestes communicatifs de l'adulte est complexe. Pris ensemble, ces résultats suggèrent que le partage de significations sur l'usage culturel des objets représente un type de connaissances communes qui permettent au bébé et à ses protagonistes de communiquer.

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Abstract