931 research outputs found

    Portable Instrument for Detection of Surface Flaws Using EMATs

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    The work reported here is the development of a first prototype portable ultrasonic inspection instrument based on EMAT (electromagnetic acoustic transducer) technology. The goal was to demonstrate EMAT inspection capabilities for small-size flaws in metal parts and to build a self-contained NDE unit that had a high degree of signal processing on-board so that human interpretation was minimized. The unit also served as a test bed, so that a number of new concepts could be evaluated. This instrument is viewed as an important step in the development of future NDE equipment

    Time evolution in the Morse potential using supersymmetry: dissociation of the NO molecule

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    We present an algebraic method for treating molecular vibrations in the Morse potential perturbed by an external laser field. By the help of a complete and normalizable basis we transform the Schr\"{o}dinger equation into a system of coupled ordinary differential equations. We apply our method to calculate the dissociation probability of the NO molecule excited by chirped laser pulses. The dependence of the molecular dipole-moment on the interatomic separation is determined by a quantum-chemical method, and the corresponding transition dipole moments are given by approximate analytic expressions. These turn out to be very small between neighboring stationary states around the vibrational quantum number m=42m=42, therefore we propose to use additional pulses in order to skip this trapping state, and to obtain a reasonable dissociation probability.Comment: 4 pages, 3 figure

    Deposition of Silicon Carbide and Nitride Based Coatings by Atmospheric Plasma Spraying

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    In this work atmospheric plasma spraying of SiC and Si3N4 was investigated. Plasma spraying of these ceramics raises several problems since they would tend to decompose instead of melting at elevated temperatures during the process. To circumvent this problem the non-oxide ceramics were deposited as a composite powder mixed with non-oxide ceramic particles resulting in a ceramic/ceramic composite structure. Our findings were that using such a composite feedstock powder both oxidation and decomposition of the non-oxide particles could be avoided. A vitrified phase was also developed in the coating

    Spinal cord compression is associated with brain plasticity in degenerative cervical myelopathy.

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    The impact of spinal cord compression severity on brain plasticity and prognostic determinates is not yet fully understood. We investigated the association between the severity of spinal cord compression in patients with degenerative cervical myelopathy, a progressive disease of the spine, and functional plasticity in the motor cortex and subcortical areas using functional magnetic resonance imaging. A 3.0 T MRI scanner was used to acquire functional images of the brain in 23 degenerative cervical myelopathy patients. Patients were instructed to perform a structured finger-tapping task to activate the motor cortex to assess the extent of cortical activation.

    Discrete cilia modelling with singularity distributions

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    We discuss in detail techniques for modelling flows due to finite and infinite arrays of beating cilia. An efficient technique, based on concepts from previous ‘singularity models’ is described, that is accurate in both near and far-fields. Cilia are modelled as curved slender ellipsoidal bodies by distributing Stokeslet and potential source dipole singularities along their centrelines, leading to an integral equation that can be solved using a simple and efficient discretisation. The computed velocity on the cilium surface is found to compare favourably with the boundary condition. We then present results for two topics of current interest in biology. 1) We present the first theoretical results showing the mechanism by which rotating embryonic nodal cilia produce a leftward flow by a ‘posterior tilt,’ and track particle motion in an array of three simulated nodal cilia. We find that, contrary to recent suggestions, there is no continuous layer of negative fluid transport close to the ciliated boundary. The mean leftward particle transport is found to be just over 1 μm/s, within experimentally measured ranges. We also discuss the accuracy of models that represent the action of cilia by steady rotlet arrays, in particular, confirming the importance of image systems in the boundary in establishing the far-field fluid transport. Future modelling may lead to understanding of the mechanisms by which morphogen gradients or mechanosensing cilia convert a directional flow to asymmetric gene expression. 2) We develop a more complex and detailed model of flow patterns in the periciliary layer of the airway surface liquid. Our results confirm that shear flow of the mucous layer drives a significant volume of periciliary liquid in the direction of mucus transport even during the recovery stroke of the cilia. Finally, we discuss the advantages and disadvantages of the singularity technique and outline future theoretical and experimental developments required to apply this technique to various other biological problems, particularly in the reproductive system

    A comparative analysis of the requirements for the use of data in biobanks based in Finland, Germany, the Netherlands, Norway and the United Kingdom

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    To understand the causes of disease and improve diagnosis and treatment regimes, biomedical researchers need access to large numbers of well-characterized data and samples. Over the past decade, biobanks have been established across Europe to collect and manage access to data and samples. The challenge that we face is how to develop the tools and collaborations to enable researchers to access samples and data from a network of biobanks, rather than applying to individual biobanks. One of the perceived stumbling blocks to achieving this is represented by the different legal requirements in each country. The aim of the BioSHaRE-European Union (EU) project is to address these challenges by developing tools and methods for researchers to access and use pooled data from different cohort and biobank studies. The purpose of this article is to identify and compare the key legal requirements regarding research use of data across biobanks based in Finland Germany, the Netherlands, Norway and the UK. Our investigation starts with the analysis of the key differences for the use of data between these countries. As a result, we identified three key areas where legal requirements differ across the five BioSHaRE-EU jurisdictions, namely, in the definition of personal data, the requirements regarding pseudonymization and processing for medical research purposes. This article provides an overview of these differences and describes them in the light of the proposed EU regulation on data protection. © The Author(s) 2014
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