851 research outputs found

    A biomechanical invariant for gait perception.

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    Psychological characteristics of children with visual impairments: learning, memory and imagery

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    The performance of children (and sometimes adults) with visual impairments (VI) on a range of tasks that reflect learning, memory and mental imagery is considered in this article. Sometimes the evidence suggests that there are impairments in performance in comparison with typically developing children with vision and sometimes some advantages emerge. The author’s aim is to describe some of her own and others’ findings and explore what they tell us about the cognitive characteristics of such children, so that progress with practical interventions can be advanced through understanding. The article starts by focusing on social-cognitive development and in particular considers the potential benefits of language in that development. This is followed by a review of some studies of learning and memory performance which provide a coherent picture of development without vision and finally ends with a consideration of spatial mental imagery

    Detecting the direction of a signal on high-dimensional spheres: Non-null and Le Cam optimality results

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    We consider one of the most important problems in directional statistics, namely the problem of testing the null hypothesis that the spike direction θ\theta of a Fisher-von Mises-Langevin distribution on the pp-dimensional unit hypersphere is equal to a given direction θ0\theta_0. After a reduction through invariance arguments, we derive local asymptotic normality (LAN) results in a general high-dimensional framework where the dimension pnp_n goes to infinity at an arbitrary rate with the sample size nn, and where the concentration κn\kappa_n behaves in a completely free way with nn, which offers a spectrum of problems ranging from arbitrarily easy to arbitrarily challenging ones. We identify various asymptotic regimes, depending on the convergence/divergence properties of (κn)(\kappa_n), that yield different contiguity rates and different limiting experiments. In each regime, we derive Le Cam optimal tests under specified κn\kappa_n and we compute, from the Le Cam third lemma, asymptotic powers of the classical Watson test under contiguous alternatives. We further establish LAN results with respect to both spike direction and concentration, which allows us to discuss optimality also under unspecified κn\kappa_n. To investigate the non-null behavior of the Watson test outside the parametric framework above, we derive its local asymptotic powers through martingale CLTs in the broader, semiparametric, model of rotationally symmetric distributions. A Monte Carlo study shows that the finite-sample behaviors of the various tests remarkably agree with our asymptotic results.Comment: 47 pages, 4 figure

    Cystic fibrosis: NHLBI workshop on the primary prevention of chronic lung diseases

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    Cystic fibrosis (CF) is a life-limiting, monogenic disorder characterized by chronic sinopulmonary and gastrointestinal involvement. Progressive pulmonary disease leads to death in the majority of patients. Despite its well-defined molecular basis related to defects in the cystic fibrosis transmembrane conductance regulator anion transport channel, there are large gaps in our understanding of the origin of CF lung disease. Disease has been shown to be present in infancy, and there is mounting evidence that abnormalities begin in utero. Heterogeneity of clinical presentations and severity suggest that many factors involved in lung disease have yet to be fully elucidated. Although new advances in therapeutic treatments have shown promise in delaying disease progression, the prevention of pulmonary disease at its origin (primary prevention) should be a key goal of CF care. The objective of this workshop was to (1) review our understanding of the origins of CF lung disease, (2) determine gaps in the knowledge base that are most significant and most likely to enable prevention of CF lung disease, and (3) prioritize new research questions that will promote pulmonary health in both CF and other childhood lung diseases. The goal of this report is to provide recommendations for future research that will improve our understanding of pulmonary development in health and disease, improve outcome measures and biomarkers for early lung disease, and determine therapeutic targets and strategies to prevent the development of lung disease in children with CF

    A window on reality: perceiving edited moving images

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    Edited moving images entertain, inform, and coerce us throughout our daily lives, yet until recently, the way people perceive movies has received little psychological attention. We review the history of empirical investigations into movie perception and the recent explosion of new research on the subject using methods such as behavioral experiments, functional magnetic resonance imagery (fMRI) eye tracking, and statistical corpus analysis. The Hollywood style of moviemaking, which permeates a wide range of visual media, has evolved formal conventions that are compatible with the natural dynamics of attention and humans’ assumptions about continuity of space, time, and action. Identifying how people overcome the sensory differences between movies and reality provides an insight into how the same cognitive processes are used to perceive continuity in the real world

    3D City Models and urban information: Current issues and perspectives

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    Considering sustainable development of cities implies investigating cities in a holistic way taking into account many interrelations between various urban or environmental issues. 3D city models are increasingly used in different cities and countries for an intended wide range of applications beyond mere visualization. Could these 3D City models be used to integrate urban and environmental knowledge? How could they be improved to fulfill such role? We believe that enriching the semantics of current 3D city models, would extend their functionality and usability; therefore, they could serve as integration platforms of the knowledge related to urban and environmental issues allowing a huge and significant improvement of city sustainable management and development. But which elements need to be added to 3D city models? What are the most efficient ways to realize such improvement / enrichment? How to evaluate the usability of these improved 3D city models? These were the questions tackled by the COST Action TU0801 “Semantic enrichment of 3D city models for sustainable urban development”. This book gathers various materials developed all along the four year of the Action and the significant breakthroughs

    Mobilisation of arsenic from bauxite residue (red mud) affected soils: effect of pH and redox conditions

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    The tailings dam breach at the Ajka alumina plant, western Hungary in 2010 introduced ~1 million m3 of red mud suspension into the surrounding area. Red mud (fine fraction bauxite residue) has a characteristically alkaline pH and contains several potentially toxic elements, including arsenic. Aerobic and anaerobic batch experiments were prepared using soils from near Ajka in order to investigate the effects of red mud addition on soil biogeochemistry and arsenic mobility in soil–water experiments representative of land affected by the red mud spill. XAS analysis showed that As was present in the red mud as As(V) in the form of arsenate. The remobilisation of red mud associated arsenate was highly pH dependent and the addition of phosphate to red mud suspensions greatly enhanced As release to solution. In aerobic batch experiments, where red mud was mixed with soils, As release to solution was highly dependent on pH. Carbonation of these alkaline solutions by dissolution of atmospheric CO2 reduced pH, which resulted in a decrease of aqueous As concentrations over time. However, this did not result in complete removal of aqueous As in any of the experiments. Carbonation did not occur in anaerobic experiments and pH remained high. Aqueous As concentrations initially increased in all the anaerobic red mud amended experiments, and then remained relatively constant as the systems became more reducing, both XANES and HPLC–ICP-MS showed that no As reduction processes occurred and that only As(V) species were present. These experiments show that there is the potential for increased As mobility in soil–water systems affected by red mud addition under both aerobic and anaerobic conditions
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