6,089 research outputs found

    Review on the epidemiology and dynamics of BSE epidemics

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    The paper describes how the comprehensive surveillance of bovine spongiform encephalopathy (BSE) and studies carried out on these data has enhanced our knowledge of the epidemiology of BSE. Around 7 000 BSE cases were detected through the screening of about 50 million cattle with rapid tests in Europe. It confirmed that the clinical surveillance had a poor capacity to detect cases, and also showed the discrepancy of this passive surveillance efficiency between regions and production types (dairy/beef). Other risk factors for BSE were being in a dairy herd (three times more than beef), having a young age at first calving (for dairy cattle), being autumn-born (dairy and beef), and being in a herd with a very high milk yield. These findings focus the risk on the feeding regimen of calves/heifers. Several epidemiological studies across countries suggest that the feedborne source related to meat and bone meal (MBM) is the only substantiated route of infection Âż even after the feed ban Âż, while it is not possible to exclude maternal transmission or milk replacers as a source of some infections. In most European countries, the average age of the cases is increasing over time and the prevalence decreasing, which reflects the effectiveness of control measures. Consistent results on the trend of the epidemic were obtained using back-calculation modelling, the R0 approach and Age-Period-Cohort models. Furthermore, active surveillance also resulted in the finding of atypical cases. These are distinct from previously found BSE and classified in two different forms based on biochemical characteristics; their prevalence is very low (36 cases up to 1st September 2007), affected animals were old and some of them displayed clinical signs. The origin and possibility of natural transmission is unknown

    Varying Coefficient Tensor Models for Brain Imaging

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    We revisit a multidimensional varying-coefficient model (VCM), by allowing regressor coefficients to vary smoothly in more than one dimension, thereby extending the VCM of Hastie and Tibshirani. The motivating example is 3-dimensional, involving a special type of nuclear magnetic resonance measurement technique that is being used to estimate the diffusion tensor at each point in the human brain. We aim to improve the current state of the art, which is to apply a multiple regression model for each voxel separately using information from six or more volume images. We present a model, based on P-spline tensor products, to introduce spatial smoothness of the estimated diffusion tensor. Since the regression design matrix is space-invariant, a 4-dimensional tensor product model results, allowing more efficient computation with penalized array regression

    A developmental investigation of the relationship between appraisals and peer self-esteem in children experiencing peer-aggression

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    Transactional models of stress and coping emphasize the role played by cognitive appraisals in determining psychological adjustment (Lazarus, 1999). This proposition has been supported by research examining young people's adjustment in relation to family conflict and break-up (Grych et al., 1992). Furthermore, this literature suggests that there is a change in the relationship between appraisals and adjustment at around 10 years of age: specificity of appraisal type (e.g. threat, blame) becomes relevant to outcome after 10 years, whereas before 10 there are either no effects of appraisal on adjustment or a diffuse effect of 'negative' appraisals more generally (Jouriles et al., 2000). However, it is currently unclear whether this developmental progression can be generalized from familial- to social-stressors experienced by children and young people. The current study therefore evaluates the model within the context of a commonly experienced social childhood stressor: peer-aggression

    Space-Varying Coefficient Models for Brain Imaging

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    The methodological development and the application in this paper originate from diffusion tensor imaging (DTI), a powerful nuclear magnetic resonance technique enabling diagnosis and monitoring of several diseases as well as reconstruction of neural pathways. We reformulate the current analysis framework of separate voxelwise regressions as a 3d space-varying coefficient model (VCM) for the entire set of DTI images recorded on a 3d grid of voxels. Hence by allowing to borrow strength from spatially adjacent voxels, to smooth noisy observations, and to estimate diffusion tensors at any location within the brain, the three-step cascade of standard data processing is overcome simultaneously. We conceptualize two VCM variants based on B-spline basis functions: a full tensor product approach and a sequential approximation, rendering the VCM numerically and computationally feasible even for the huge dimension of the joint model in a realistic setup. A simulation study shows that both approaches outperform the standard method of voxelwise regressions with subsequent regularization. Due to major efficacy, we apply the sequential method to a clinical DTI data set and demonstrate the inherent ability of increasing the rigid grid resolution by evaluating the incorporated basis functions at intermediate points. In conclusion, the suggested fitting methods clearly improve the current state-of-the-art, but ameloriation of local adaptivity remains desirable

    Do coping variables mediate the effect of social identity on psychological wellbeing for bullied children?

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    Prsentation examining how coping variables mediate the effect of social identity on psychological wellbeing for bullied children. Demonstrates a need to understand how children interpret their situation, not just how they cope with it. This is independent of minority/majority ethnic status

    Towards Scalable Visual Exploration of Very Large RDF Graphs

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    In this paper, we outline our work on developing a disk-based infrastructure for efficient visualization and graph exploration operations over very large graphs. The proposed platform, called graphVizdb, is based on a novel technique for indexing and storing the graph. Particularly, the graph layout is indexed with a spatial data structure, i.e., an R-tree, and stored in a database. In runtime, user operations are translated into efficient spatial operations (i.e., window queries) in the backend.Comment: 12th Extended Semantic Web Conference (ESWC 2015

    Investigating the timecourse of accessing conversational implicatures during incremental sentence interpretation

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    Many contextual inferences in utterance interpretation are explained as following from the nature of conversation and the assumption that participants are rational. Recent psycholinguistic research has focussed on certain of these ‘Gricean’ inferences and have revealed that comprehenders can access them in online interpretation. However there have been mixed results as to the time-course of access. Some results show that Gricean inferences can be accessed very rapidly, as rapidly as any other contextually specified information (Sedivy, 2003; Grodner, Klein, Carbery, & Tanenhaus, 2010); while other studies looking at the same kind of inference suggest that access to Gricean inferences are delayed relative to other aspects of semantic interpretation (Huang & Snedeker, 2009; in press). While previous timecourse research has focussed on Gricean inferences that support the online assignment of reference to definite expressions, the study reported here examines the timecourse of access to scalar implicatures, which enrich the meaning of an utterance beyond the semantic interpretation. Even if access to Gricean inference in support of reference assignment may be rapid, it is still unknown whether genuinely enriching scalar implicatures are delayed. Our results indicate that scalar implicatures are accessed as rapidly as other contextual inferences. The implications of our results are discussed in reference to the architecture of language comprehension

    Guidelines for a Space Propulsion Device Based on Heim's Quantum Theory

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    The text of the calligraphy on the front page means Cosmos, comprising the two chinese symbols for space and time. This calligraphy was done by Hozumi Gensho Roshi, Professor of Applied Sci-ences at Hanazono University, Kyoto, Japan in September 2003. The two red squares depict the sea

    Treatment of von Willebrand disease

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    Summary. von Willebrand disease is the most frequent of inherited bleeding disorders (1:100 affected individuals in the general population). The aim of treatment is to correct the dual defects of haemostasis, i.e., abnormal coagulation expressed by low levels of factor VIII and abnormal platelet adhesion expressed by a prolonged bleeding time. There are two main options available for the management of von Willebrand disease: desmopressin and transfusion therapy with blood products. Desmopressin is the treatment of choice in patients with type 1 von Willebrand disease, who account for approximately 80% of cases. This pharmacological compound raises endogenous factor VIII and von Willebrand factors and thereby corrects the intrinsic coagulation defect and the prolonged bleeding time in most type 1 patients. In type 3 and in the majority of type 2 patients desmopressin is not effective, and it is necessary to resort to plasma concentrates containing factor VIII and von Willebrand factor. Treated with virucidal methods, these concentrates are effective and currently safe, but the bleeding time defect is not always corrected by them. Platelet concentrates or desmopressin can be used as adjunctive treatments when poor correction of the bleeding time after concentrates is associated with continued bleeding

    Geometry and symmetries of multi-particle systems

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    The quantum dynamical evolution of atomic and molecular aggregates, from their compact to their fragmented states, is parametrized by a single collective radial parameter. Treating all the remaining particle coordinates in d dimensions democratically, as a set of angles orthogonal to this collective radius or by equivalent variables, bypasses all independent-particle approximations. The invariance of the total kinetic energy under arbitrary d-dimensional transformations which preserve the radial parameter gives rise to novel quantum numbers and ladder operators interconnecting its eigenstates at each value of the radial parameter. We develop the systematics and technology of this approach, introducing the relevant mathematics tutorially, by analogy to the familiar theory of angular momentum in three dimensions. The angular basis functions so obtained are treated in a manifestly coordinate-free manner, thus serving as a flexible generalized basis for carrying out detailed studies of wavefunction evolution in multi-particle systems.Comment: 37 pages, 2 eps figure
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