A weakly informative prior for Bayesian dynamic model selection with applications in fMRI

In recent years, Bayesian statistics methods in neuroscience have been showing important advances. In particular, detection of brain signals for studying the complexity of the brain is an active area of research. Functional magnetic resonance imagining (fMRI) is an important tool to determine which parts of the brain are activated by different types of physical behavior. According to recent results, there is evidence that the values of the connectivity brain signal parameters are close to zero and due to the nature of time series fMRI data with high-frequency behavior, Bayesian dynamic models for identifying sparsity are indeed far-reaching. We propose a multivariate Bayesian dynamic approach for model selection and shrinkage estimation of the connectivity parameters. We describe the coupling or lead-lag between any pair of regions by using mixture priors for the connectivity parameters and propose a new weakly informative default prior for the state variances. This framework produces one-step-ahead proper posterior predictive results and induces shrinkage and robustness suitable for fMRI data in the presence of sparsity. To explore the performance of the proposed methodology, we present simulation studies and an application to functional magnetic resonance imaging data

Organisation et automatisation des PMI

Available at INIST (FR), Document Supply Service, under shelf-number : AR 14451 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc

Adverse Skin Reactions to Plants and Plant Products

Plants are a significant cause of skin reactions worldwide. Because most affected individuals do not present to a dermatologist, it is likely that skin reactions to plants are under-reported. Plants may induce mechanical irritant reactions, e.g., due to spines or hairs. Trauma to the plant may release chemical irritants such as calcium oxalate crystals or phorbol esters. Skin contact with furocoumarins in some plants, notably members of the Apiaceae, followed by exposure to ultraviolet A, induces a characteristic streaky rash leading to hyperpigmentation (phototoxicity). A few plant species including nettles (Urtica spp.) inject toxins into unsuspecting predators, a form of chemical warfare. These toxins include histamine, inducing nettle rash (urticaria). Other nonprotein plant constituents such as cinnamic acid derivatives may induce urticaria by a pharmacological mechanism. However, some individuals may develop immunologically mediated urticaria and even anaphylaxis caused by immediate hypersensitivity to plants or plant products, including fruit, vegetables, and nuts. Finally, a few plant families have the potential to induce allergic contact dermatitis; these include the daisy family (Asteraceae/Compositae) and poison ivy family (Anacardiaceae)