813 research outputs found

    Neuropsychological Assessment of Children With Reading Disabilities From 8 to 10 Years Old: An Exploratory Portuguese Study

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    Abstract Reading disabilities are one of the most significant causes of school failure and may result from different causes and cognitive processes. A comprehensive battery of neuropsychological tests was applied to a control group of 102 children (46 girls, 56 boys) with no history of learning disabilities and 32 children (13 girls, 19 boys) with poor reading achievement (PRA) to characterize their cognitive profile. A principal component analysis of the cognitive measures was undertaken to identify cognitive domains. Age-adjusted normative data were computed from controls for verbal and visuospatial abilities, psychomotor skills, executive functions, and a total score. Significant differences were found between the 2 groups. Although single tests could not identify children with PRA, measures of oral and written language, immediate and working memory, calculation, and verbal learning discriminated the 2 groups. A logistic regression model using these factors allowed us to identify 91.2% of healthy children and 96.9% of children with PRA. PRA may result from different patterns of cognitive difficulties, and it is more common in children with oral language and working-memory deficits. Wide-range cognitive testing is necessary to identify strong and weak areas to plan personalized intervention program

    The kinematics of bidisperse granular roll waves

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    Small perturbations to a steady uniform granular chute flow can grow as the material moves downslope and develop into a series of surface waves that travel faster than the bulk flow. This roll wave instability has important implications for the mitigation of hazards due to geophysical mass flows, such as snow avalanches, debris flows and landslides, because the resulting waves tend to merge and become much deeper and more destructive than the uniform flow from which they form. Natural flows are usually highly polydisperse and their dynamics is significantly complicated by the particle size segregation that occurs within them. This study investigates the kinematics of such flows theoretically and through small-scale experiments that use a mixture of large and small glass spheres. It is shown that large particles, which segregate to the surface of the flow, are always concentrated near the crests of roll waves. There are different mechanisms for this depending on the relative speed of the waves, compared to the speed of particles at the free surface, as well as on the particle concentration. If all particles at the surface travel more slowly than the waves, the large particles become concentrated as the shock-like wavefronts pass them. This is due to a concertina-like effect in the frame of the moving wave, in which large particles move slowly backwards through the crest, but travel quickly in the troughs between the crests. If, instead, some particles on the surface travel more quickly than the wave and some move slower, then, at low concentrations, large particles can move towards the wave crest from both the forward and rearward sides. This results in isolated regions of large particles that are trapped at the crest of each wave, separated by regions where the flow is thinner and free of large particles. There is also a third regime arising when all surface particles travel faster than the waves, which has large particles present everywhere but with a sharp increase in their concentration towards the wave fronts. In all cases, the significantly enhanced large particle concentration at wave crests means that such flows in nature can be especially destructive and thus particularly hazardous

    Stronger diversity effects with increased environmental stress : a study of multitrophic interactions between oak, powdery mildew and ladybirds

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    Recent research has suggested that increasing neighbourhood tree species diversity may mitigate the impact of pests or pathogens by supporting the activities of their natural enemies and/or reducing the density of available hosts. In this study, we attempted to assess these mechanisms in a multitrophic study system of young oak (Quercus), oak powdery mildew (PM, caused by Erysiphe spp.) and a mycophagous ladybird (Psyllobora vigintiduo-punctata). We assessed ladybird mycophagy on oak PM in function of different neighbourhood tree species compositions. We also evaluated whether these species interactions were modulated by environmental conditions as suggested by the Stress Gradient Hypothesis. We adopted a complementary approach of a field experiment where we monitored oak saplings subjected to a reduced rainfall gradient in a young planted forest consisting of different tree species mixtures, as well as a lab experiment where we independently evaluated the effect of different watering treatments on PM infections and ladybird mycophagy. In the field experiment, we found effects of neighbourhood tree species richness on ladybird mycophagy becoming more positive as the target trees received less water. This effect was only found as weather conditions grew drier. In the lab experiment, we found a preference of ladybirds to graze on infected leaves from trees that received less water. We discuss potential mechanisms that might explain this preference, such as emissions of volatile leaf chemicals. Our results are in line with the expectations of the Natural Enemies Hypothesis and support the hypothesis that biodiversity effects become stronger with increased environmental stress

    Pulpal sequelae after trauma to anterior teeth among adult Nigerian dental patients

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    <p>Abstract</p> <p>Background</p> <p>Epidemiological studies show that about 11.6% to 33.0% of all boys and about 3.6% to 19.3% of all girls suffer dental trauma of varying severity before the age of 12 years. Moderate injuries to the periodontium such as concussion and subluxation are usually associated with relatively minor symptoms and hence may go unnoticed by the patient or the dentist, if consulted. Patients with these kinds of injuries present years after a traumatic accident most of the time with a single discoloured tooth. This study sets out to document the incidence of various posttraumatic sequelae of discoloured anterior teeth among adult Nigerian dental patients.</p> <p>Methods</p> <p>One hundred and sixty eight (168) traumatized discoloured anterior teeth in 165 patients were studied. Teeth with root canal treatment were excluded from the study. Partial obliteration was recorded when the pulp chamber or root canal was not discernible or reduced in size on radiographs, total obliteration was recorded when pulp chamber and root canal were not discernible. A retrospective diagnosis of concussion was made from patient's history of trauma to the tooth without abnormal loosening, while subluxation was made from patient's history of trauma to the tooth with abnormal loosening.</p> <p>Results</p> <p>Of the 168 traumatized discoloured anterior teeth, 47.6% and 31.6% had partial and total obliteration of the pulp canal spaces respectively, 20.8% had pulpal necrosis. Concussion and subluxation injuries resulted more in obliteration of the pulp canal space, while fracture of the teeth resulted in more pulpal necrosis (p < 0.001). Injuries sustained during the 1<sup>st </sup>and 2<sup>nd </sup>decade of life resulted more in obliteration of the pulp canal space, while injuries sustained in the 3<sup>rd </sup>decade resulted in more pulpal necrosis.</p> <p>Conclusion</p> <p>Calcific metamorphosis developed more in teeth with concussion and subluxation injuries. Pulpal necrosis occurred more often in traumatized teeth including fractures.</p

    What traits are carried on mobile genetic elements, and why?

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    Although similar to any other organism, prokaryotes can transfer genes vertically from mother cell to daughter cell, they can also exchange certain genes horizontally. Genes can move within and between genomes at fast rates because of mobile genetic elements (MGEs). Although mobile elements are fundamentally self-interested entities, and thus replicate for their own gain, they frequently carry genes beneficial for their hosts and/or the neighbours of their hosts. Many genes that are carried by mobile elements code for traits that are expressed outside of the cell. Such traits are involved in bacterial sociality, such as the production of public goods, which benefit a cell's neighbours, or the production of bacteriocins, which harm a cell's neighbours. In this study we review the patterns that are emerging in the types of genes carried by mobile elements, and discuss the evolutionary and ecological conditions under which mobile elements evolve to carry their peculiar mix of parasitic, beneficial and cooperative genes

    Ambiguidade do cuidado na vivência do consumidor de drogas

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    RESUMO Objetivo Compreender a percepção de usuários de um Centro de Atenção Psicossocial sobre o cuidado no contexto do consumo de drogas. Métodos Estudo fundamentado na Fenomenologia de Maurice Merleau-Ponty, desenvolvido no segundo semestre do ano de 2015. Foram realizados dois encontros de Grupo Focal, com dez usuários de um Centro de Atenção Psicossocial Álcool e outras Drogas. Os dados foram submetidos à técnica Analítica da Ambiguidade. Resultados O consumo de drogas ora proporciona ao consumidor sensações de prazer, ora contribui para a ocorrência de prejuízos biopsicossociais e/ou novas possibilidades de relação com a droga. Conclusões O consumo de drogas constitui-se em um processo ambíguo, que corresponde à percepção de diferentes perfis de cuidado na relação do consumidor com a droga. Cabe aos profissionais de saúde reconhecer as diversas possibilidades de cuidado e favorecer a construção de projetos terapêuticos baseados na escuta e respeito às necessidades dos consumidores de drogas
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