132 research outputs found

    Deriving animations from recursive definitions

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    This paper describes a generic method to derive an animation from a recursive definition, with the objective of debugging and understanding this definition by expliciting its control structure. This method is based on a well known algorithm of factorizing a recursive function into the composition of the producer and the consumer of its call tree. We developed a systematic method to transform both the resulting functions in order to draw the tree step by step. The theory of data types as fixed points of functors, generic recursion patterns, and monads, are fundamental to our work and are brie y presented. Using polytypic implementations of monadic recursion patterns and an application to manipulate and generate graph layouts we developed a prototype that, given a recursive function written in a subset of Haskell, returns a function whose execution yields the desired animation

    Polytipic recursion patterns

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    Comunicação apresentada em SBLP'00, Proc. 4th Brazilian Symposium on Programming Languages, Recife, May, 2000Recursive schemes over inductive data structures have been recognized as category-theoretic universals, yielding a handful of equational laws for program construction and transformation. This paper introduces the implementation of such recursion patterns as type parametric, or polytypic, functionals in the CAMILA prototyping language. Several examples are discussed

    Assertion-based slicing and slice graphs

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    This paper revisits the idea of slicing programs based on their axiomatic semantics, rather than using criteria based on control/data dependencies. We show how the forward propagation of preconditions and the backward propagation of postconditions can be combined in a new slicing algorithm that is more precise than the existing specification-based algorithms. The algorithm is based on (i) a precise test for removable statements, and (ii) the construction of a \emph{slice graph}, a program control flow graph extended with semantic labels and additional edges that ``short-circuit'' removable commands. It improves on previous approaches in two aspects: it does not fail to identify removable commands; and it produces the smallest possible slice that can be obtained (in a sense that will be made precise). Iteration is handled through the use of loop invariants and variants to ensure termination. The paper also discusses in detail applications of these forms of slicing, including the elimination of (conditionally) unreachable and dead code, and compares them to other related notions.Fundação para a Ciência e a Tecnologia (FCT

    Assertion-based slicing and slice graphs

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    © 2010 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.This paper revisits the idea of slicing programs based on their axiomatic semantics, rather than using criteria based on control/data dependencies. We show how the forward propagation of preconditions and the backward propagation of post conditions can be combined in a new slicing algorithm that is more precise than the existing specification-based algorithms. The algorithm is based on (i) a precise test for removable statements, and (ii) the construction of a slice graph, a program control flow graph extended with semantic labels. It improves on previous approaches in two aspects: it does not fail to identify removable commands; and it produces the smallest possible slice that can be obtained (in a sense that will be made precise). The paper also reviews in detail, through examples, the ideas behind the use of preconditions and post conditions for slicing programs.Fundação para a Ciência e a Tecnologia (FCT) - RESCUE (PTDC/EIA/65862/2006)

    Late weaning and maternal closeness, associated with advanced motor and visual maturation, reinforce autonomy in healthy, 2-year-old children

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    We studied neurodevelopmental outcomes and behaviours in healthy 2-year old children (N = 1306) from Brazil, India, Italy, Kenya and the UK participating in the INTERGROWTH-21st Project. There was a positive independent relationship of duration of exclusive breastfeeding (EBF) and age at weaning with gross motor development, vision and autonomic physical activities, most evident if children were exclusively breastfed for ≥7 months or weaned at ≥7 months. There was no association with cognition, language or behaviour. Children exclusively breastfed from birth to6 months had, in a dose-effect pattern, adjusting for confounding factors, higher scores for emotional reactivity . The positive effect of EBF and age at weaning on gross motor, running and climbing scores was strongest among children with the highest scores in maternal closeness proxy indicators. EBF, late weaning and maternal closeness, associated with advanced motor and vision maturation, independently influence autonomous behaviours in healthy children

    Human colon-derived soluble factors modulate gut microbiota composition

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    This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY).-- et al.The commensal microbiota modulates immunological and metabolic aspects of the intestinal mucosa contributing to development of human gut diseases including inflammatory bowel disease. The host/microbiota interaction often referred to as a crosstalk, mainly focuses on the effect of the microbiota on the host neglecting effects that the host could elicit on the commensals. Colonic microenvironments from three human healthy controls (obtained from the proximal and distal colon, both in resting conditions and after immune - IL-15-and microbiota - LPS-in vitro challenges) were used to condition a stable fecal population. Subsequent 16S rRNA gene-based analyses were performed to study the effect induced by the host on the microbiota composition and function. Non-supervised principal component analysis (PCA) showed that all microbiotas, which had been conditioned with colonic microenvironments clustered together in terms of relative microbial composition, suggesting that soluble factors were modulating a stable fecal population independently from the treatment or the origin. Our findings confirmed that the host intestinal microenvironment has the capacity to modulate the gut microbiota composition via yet unidentified soluble factors. These findings indicate that an appropriate understanding of the factors of the host mucosal microenvironment affecting microbiota composition and function could improve therapeutic manipulation of the microbiota composition.BS and AH were recipients of a Ramón y Cajal postdoctoral contract and a FPI grant, respectively, from the Spanish Ministry of Economy and Competitiveness. The authors gratefully acknowledge the support of the Biotechnology and Biological Sciences Research Council (BBSRC). This research was funded by the BBSRC Institute Strategic Programme for Gut Health and Food Safety BB/J004529/1. This research was also funded by Grants AGL2010-14952 and AGL2013-44039-R from the Spanish “Plan Estatal de I + D + i,” and by Grant EM2014/046 from the “Plan galego de investigación, innovación e crecemento 2011-2015.”Peer Reviewe

    Hospitalização por pneumonia: influência de fatores socioeconômicos e gestacionais em uma coorte de crianças no Sul do Brasil

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    OBJETIVO: Investigar a influência de fatores socioeconômicos e gestacionais sobre a hospitalização por pneumonia no período pós-neonatal. MATERIAL E MÉTODO: Longitudinal. Crianças com idade entre 28 e 364 dias, nascidas na cidade de Pelotas, RS (Brasil), em 1993. A definição de caso foi a permanência em ambiente hospitalar por um período igual ou superior a 24 horas em conseqüência de pneumonia. Foi aplicado delineamento longitudinal. RESULTADOS: Dentre as 5.304 crianças da coorte, 152 (2,9%) foram hospitalizadas por pneumonia no período. O valor preditivo positivo do diagnóstico clínico comparado com o radiológico alcançou 76%. A análise através de regressão logística mostrou que a classe social e a escolaridade materna estiveram forte e inversamente associadas à admissão hospitalar. Filhos de mães adolescentes tiveram risco duplicado à internação; paridade igual ou superior a três representou risco 2,8 vezes maior em relação às mães primíparas; ganho de peso inferior a 10 kg durante a gestação implicou risco cerca de 40% maior à hospitalização. CONCLUSÕES: A classe social e a escolaridade materna foram os principais determinantes da hospitalização. Idade e paridade materna e o ganho de peso durante a gestação foram também fatores de risco importantes.OBJECTIVE: To investigate the influence of socioeconomic and gestational factors on admission due to pneumonia in the post-neonatal period. METHODOLOGY: Cohort. Children born in the city Pelotas, Brazil, in 1993. Cases were children admitted to hospital for 24 hours or more, between the ages of 28 and 364 days, with a diagnosis of pneumonia. RESULTS: Of the 5,304 children in the cohort, 152 (2.9%) were hospitalized with pneumonia. The positive preditive value of the clinical diagnosis compared to the radiological assessment was 76%. Analysis by conditional logistic regression showed that social class and maternal schooling were strongly inversely associated with pneumonia. Children of adolescent mothers were twice as likely to be admitted. The relative risk for children whose mothers were of parity three or greater was 2.8 relative to primiparae. Maternal weight gain during pregnancy of less than 10 kg was associated with a 40% increase in risk. CONCLUSION: Socioeconomic factors were important determinants of pneumonia admissions. Maternal age, parity and weight gain were also significant risk factors

    Integrating the pastoral component in agricultural systems

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    This paper aims to discuss the impact of the introduction of pastures and grazing animals in agricultural systems. For the purposes of this manuscript, we focus on within-farm integrated crop-livestock systems (ICLS), typical of Southern Brazil. These ICLS are designed to create and enhance the synergisms and emergent properties have arisen from agricultural areas where livestock activities are integrated with crops. We show that the introduction of the crop component will affect less the preceding condition than the introduction of the livestock component. While the introduction of crops in pastoral systems represents increasing diversity of the plant component, the introduction of animals would represent the entry of new flows and interactions within the system. Thus, given the new complexity levels achieved from the introduction of grazing, the probability of arising emergent properties is theoretically much higher. However, grazing management is vital in determining the success or failure of such initiative. The grazing intensity practiced during the pasture phase would affect the canopy structure and the forage availability to animals. In adequate and moderate grazing intensities, it is possible to affirm that livestock combined with crops (ICLS) has a potential positive impact. As important as the improvements that grazing animals can generate to the soil-plant components, the economic resilience remarkably increases when pasture rotations are introduced compared with purely agriculture systems, particularly in climate-risk situations. Thus, the integration of the pastoral component can enhance the sustainable intensification of food production, but it modifies simple, pure agricultural systems into more complex and knowledge-demanding production systems
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