Deconvolution estimation of nerve conduction velocity distribution

A conduction velocity distribution (CVD) estimator that incorporates volume conductor modeling of the nerve-evoked response is introduced in this paper. The CVD estimates are obtained from two compound nerve action potentials (CNAP) recorded at the skin surface. A third channel is introduced in order to assess the estimator performance in the experimental case. The relevance of using an accurate signal model is shown by comparing the performance of the proposed estimator with a previous approach based on a different CNAP model. The performance of the proposed estimator is evaluated for simulated and experimental data. The study assesses signal-to-noise ratio immunity and sensitivity to errors in the model parameters.     

A component-based parallel infrastructure for the simulation of fluid–structure interaction

The Uintah computational framework is a component-based infrastructure, designed for highly parallel simulations of complex fluid–structure interaction problems. Uintah utilizes an abstract representation of parallel computation and communication to express data dependencies between multiple physics components. These features allow parallelism to be integrated between multiple components while maintaining overall scalability. Uintah provides mechanisms for load-balancing, data communication, data I/O, and checkpoint/restart. The underlying infrastructure is designed to accommodate a range of PDE solution methods. The primary techniques described here, are the material point method (MPM) for structural mechanics and a multi-material fluid mechanics capability. MPM employs a particle-based representation of solid materials that interact through a semi-structured background grid. We describe a scalable infrastructure for problems with large deformation, high strain rates, and complex material behavior. Uintah is a product of the University of Utah Center for Accidental Fires and Explosions (C-SAFE), a DOE-funded Center of Excellence. This approach has been used to simulate numerous complex problems, including the response of energetic devices subject to harsh environments such as hydrocarbon pool fires. This scenario involves a wide range of length and time scales including a relatively slow heating phase punctuated by pressurization and rupture of the device.     

Nonlinear adaptive filtering of stimulus artifact

Noninvasive measurements of somatosensory evoked potentials have both clinical and research applications. The electrical artifact which results from the stimulus is an interference which can distort the evoked signal, and introduce errors in response onset timing estimation. Given that this interference is synchronous with the evoked signal, it cannot be reduced by the conventional technique of ensemble averaging. The technique of adaptive noise cancelling has potential in this regard however, and has been used effectively in other similar problems. An adaptive noise cancelling filter which uses a neural network as the adaptive element is investigated in this application. The filter is implemented and performance determined in the cancelling of artifact for in vivo measurements on the median nerve. A technique of segmented neural network training is proposed in which the network is trained on that segment of the record time window which does not contain the evoked signal. The neural network is found to generalize well from this training to include the segment of the window containing the evoked signal. Both quantitative and qualitative measures show that significant stimulus artifact reduction is achieved.     

Some considerations on the reliability and validity of the Alcohol Expectancy Questionnaire for Adolescents.

Reviews the material presented in the S. A. Brown et al (see record 1988-28300-001) report on the reliability and validity of the Alcohol Expectancy Questionnaire for Adolescents (AEQ-A). Data are presented that suggest that the reliability and validity of the AEQ-A remain to be fully established. A preliminary outline of a potential theoretical direction is provided that applies Rotter's Social Learning Theory (J. B. Rotter, 1954 and 1982) as a framework for future work with alcohol-related expectancies and other cognitive-behavioral research on alcohol. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pathogenic mechanisms in the rheumatoid nodule: comparison of proinflammatory cytokine production and cell adhesion molecule expression in rheumatoid nodules and synovial membranes from the same patient

OBJECTIVE: To investigate the production of proinflammatory cytokines and expression of cell adhesion molecules in the rheumatoid nodule. METHODS: Cytokine content (tumor necrosis factor alpha [TNFalpha], interleukin-1beta [IL-1beta], and IL-1 receptor antagonist [IL-1Ra]), at the messenger RNA (mRNA) and protein levels, and cell adhesion molecule expression were studied in 16 rheumatoid nodules and 6 synovial membranes. RESULTS: Macrophages in the rheumatoid nodules contained TNFalpha, IL-1beta, and IL-1Ra mRNA and protein, particularly in perivascular cells of the stroma and in the palisading layer. All cell adhesion molecules studied were expressed in both the rheumatoid nodules and synovial membranes, with increased expression of E-selectin in the rheumatoid nodule compared with the synovial membrane, and with the absence of vascular cell adhesion molecule 1 expression on cells of the palisading layer in the rheumatoid nodule. CONCLUSION: The presence of similar proinflammatory cytokines and cell adhesion molecules in the rheumatoid nodule and synovial membrane suggests that similar pathogenic processes result in the chronic inflammation and tissue destruction in these lesions.     

Expression of peptide YY in all four islet cell types in the developing mouse pancreas suggests a common peptide YY-producing progenitor

The islets of Langerhans contain four distinct endocrine cell types producing the hormones glucagon, insulin, somatostatin and pancreatic polypeptide. These cell lineages are thought to arise from a common, multipotential progenitor cell whose identity has not been well established. The pancreatic and intestinal hormone, peptide YY, has been previously identified in glucagon-producing cells in islets; however, transgenic mice expressing Simian Virus 40 large T antigen under the control of the peptide YY gene expressed the oncoprotein in beta, delta and pancreatic polypeptide cells, and occasionally developed insulinomas, suggesting relationships between peptide YY-producing cells and several islet cell lineages. The four established pancreatic islet cell types were examined for coexpression of peptide YY in islets of normal and transgenic mice throughout development. Peptide YY immunoreactivity was identified in the earliest endocrine cells in the fetal pancreas and was coexpressed in each islet cell type during development. Peptide YY showed a high degree of co-localization with glucagon- and insulin-producing cells in early pancreatic development, but by adulthood, peptide YY was expressed in less than half of the alpha cells and was no longer expressed in beta cells. Peptide YY was also coexpressed with somatostatin and pancreatic polypeptide when these cell types first appeared, but most delta and pancreatic polypeptide cells continued to express peptide YY throughout development. The use of conditions that distinguish peptide YY from the related peptides, pancreatic polypeptide and neuropeptide Y, as well as the ability of the peptide YY gene to direct expression of a reporter gene in islets of transgenic mice, establishes expression of peptide YY in the earliest pancreatic endocrine cells.(ABSTRACT TRUNCATED AT 250 WORDS)