326 research outputs found

    Abnormalities in whisking behaviour are associated with lesions in brain stem nuclei in a mouse model of amyotrophic lateral sclerosis

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    The transgenic SOD1G93A mouse is a model of human amyotrophic lateral sclerosis (ALS) and recapitulates many of the pathological hallmarks observed in humans, including motor neuron degeneration in the brain and the spinal cord. In mice, neurodegeneration particularly impacts on the facial nuclei in the brainstem. Motor neurons innervating the whisker pad muscles originate in the facial nucleus of the brain stem, with contractions of these muscles giving rise to “whisking” one of the fastest movements performed by mammals. A longitudinal study was conducted on SOD1G93A mice and wild-type litter mate controls, comparing: (i) whisker movements using high-speed video recordings and automated whisker tracking, and (ii) facial nucleus degeneration using MRI. Results indicate that while whisking still occurs in SOD1G93A mice and is relatively resistant to neurodegeneration, there are significant disruptions to certain whisking behaviours, which correlate with facial nuclei lesions, and may be as a result of specific facial muscle degeneration. We propose that measures of mouse whisker movement could potentially be used in tandem with measures of limb dysfunction as biomarkers of disease onset and progression in ALS mice and offers a novel method for testing the efficacy of novel therapeutic compounds

    Control of additive manufacturing for radio frequency devices with spatially varying dielectric properties

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    Additive manufacturing (AM) is increasingly being used to fabricate end-use and high-value-added parts in a range of industries. AM’s ability to create complex geometries and vary the internal composition of a part has enabled the design of many novel devices, including radio frequency (RF) devices that rely on the spatial variation of electromagnetic (EM) properties. However, current AM processes for fabricating complex parts are typically run without any part monitoring or online feedback control, and as a result, the printed parts may be compromised by defects or have poor tolerances. Manufacturing parts in this way also requires extra quality testing since there is no knowledge of their interior quality. For these reasons, introducing process monitoring and corrective action to the AM process has become an important area of research as AM is being used to create safety-critical parts. This work proposes a control algorithm to enable closed-loop control of an EM property, specifically dielectric permittivity, within a print using a fused filament fabrication (FFF) printer. The control system used a split-ring resonator (SRR) to measure the permittivity of printed thermoplastic, and the control action was applied by updating the printed infill density layer to layer. This control system was tested by printing a proof-of-concept graded-index (GRIN) lens with spatially varying permittivity through the lens’ length. The results demonstrate the ability of the controller to follow a constantly varying reference signal, indicating the potential of closed-loop control for improved fabrication of functional RF devices that depend on precise variations in relative permittivity

    Reconstruction of road defects and road roughness classification using vehicle responses with artificial neural networks simulation

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    The road damage assessment methodology in this paper utilizes an artificial neural network that reconstructs road surface profiles from measured vehicle accelerations. The paper numerically demonstrates the capabilities of such a methodology in the presence of noise, changing vehicle mass, changing vehicle speeds and road defects. In order to avoid crowding out understanding of the methodology, a simple linear pitch-plane model is employed. Initially, road profiles from known roughness classes were applied to a physical model to calculate vehicle responses. The calculated responses and road profiles were used to train an artificial neural network. In this way, the network renders corresponding road profiles on the availability of fresh data on model responses. The results show that the road profiles and associated defects can be reconstructed to within a 20% error at a minimum correlation value of 94%.The Council for Scientific and Industrial Research (CSIR) and the National Research Foundation under the South African Co-operation Fund for Scientific Research and Technological Developments.http://www.elsevier.com/locate/jterraai201

    Numerical design of microporous carbon binder domains phase in composite cathodes for lithium-ion batteries

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    Lithium-ion battery (LIB) performance can be significantly affected by the nature of the complex electrode microstructure. The carbon binder domain (CBD) present in almost all LIB electrodes is used to enhance mechanical stability and facilitate electronic conduction, and understanding the CBD phase microstructure and how it affects the complex coupled transport processes is crucial to LIB performance optimization. In this work, the influence of microporosity in the CBD phase has been studied in detail for the first time, enabling insight into the relationships between the CBD microstructure and the battery performance. To investigate the effect of the CBD pore size distributions, a random field method is used to generate in silico a multiple-phase electrode structure, including bimodal pore size distributions seen in practice and microporous CBD with a tunable pore size and variable transport properties. The distribution of macropores and the microporous CBD phase substantially affected simulated battery performance, where battery specific capacity improved as the microporosity of the CBD phase increased

    Domain Growth and Finite-Size-Scaling in the Kinetic Ising Model

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    This paper describes the application of finite-size scaling concepts to domain growth in systems with a non-conserved order parameter. A finite-size scaling ansatz for the time-dependent order parameter distribution function is proposed, and tested with extensive Monte-Carlo simulations of domain growth in the 2-D spin-flip kinetic Ising model. The scaling properties of the distribution functions serve to elucidate the configurational self-similarity that underlies the dynamic scaling picture. Moreover, it is demonstrated that the application of finite-size-scaling techniques facilitates the accurate determination of the bulk growth exponent even in the presence of strong finite-size effects, the scale and character of which are graphically exposed by the order parameter distribution function. In addition it is found that one commonly used measure of domain size--the scaled second moment of the magnetisation distribution--belies the full extent of these finite-size effects.Comment: 13 pages, Latex. Figures available on request. Rep #9401

    Kafirin structure and functionality

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    The structural and functional properties of kafirins are reviewed. Three classes of kafirin: the a, ß and ? forms have been identified at the protein level and one, the d, has been identified only at the gene and transcript levels. All forms show high homology with the equivalent zein proteins. By analogy with the zeins it is believed that the a-kafirins probably have an extended hairpin structure in solution, comprising elements of a-helix, ß-sheet and turns folded back on itself. Kafirins are the most hydrophobic of the prolamins as shown by their solubility, and calculated hydration free energies. The proteins exhibit extensive cross-linking by disulphide bonds and on cooking form indigestible aggregates which are not solubilised by reduction of disulphide bonds. In spite of continuing studies, the reasons for the low digestibility of the protein remain uncertain and there may be several factors involved. Other research has shown that kafirins may have non-food uses and may be used to form films

    First records of a plesiosaurian (Reptilia: Sauropterygia) and an ichthyosaur (Reptilia: Ichthyosauria) from Yukon, Canada

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    An isolated centrum collected ex situ from marine shales of the Lower Cretaceous (Albian) Arctic Red Formation along the Road River represents the first documented occurrence of a plesiosaurian from Yukon. This centrum represents the northernmost occurrence of plesiosaurians in the Western Interior Sea of North America prior to the establishment of the first continuous seaway (Western Interior Seaway) connecting the Boreal and Tethyan seas. Additionally, this centrum is potentially the secondoldest elasmosaurid specimen known from North America. A second centrum, collected along the Beaver River, is likely derived from the Lower Cretaceous (Lower Albian) Garbutt Formation exposed farther upstream. It represents the first report of an ichthyosaur from Yukon. Additionally, six associated ribs collected from the Arctic Re

    Solar Wind Turbulence and the Role of Ion Instabilities

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    Roadmap on Li-ion battery manufacturing research

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    Growth in the Li-ion battery market continues to accelerate, driven primarily by the increasing need for economic energy storage for electric vehicles. Electrode manufacture by slurry casting is the first main step in cell production but much of the manufacturing optimisation is based on trial and error, know-how and individual expertise. Advancing manufacturing science that underpins Li-ion battery electrode production is critical to adding to the electrode manufacturing value chain. Overcoming the current barriers in electrode manufacturing requires advances in materials, manufacturing technology, in-line process metrology and data analytics, and can enable improvements in cell performance, quality, safety and process sustainability. In this roadmap we explore the research opportunities to improve each stage of the electrode manufacturing process, from materials synthesis through to electrode calendering. We highlight the role of new process technology, such as dry processing, and advanced electrode design supported through electrode level, physics-based modelling. Progress in data driven models of electrode manufacturing processes is also considered. We conclude there is a growing need for innovations in process metrology to aid fundamental understanding and to enable feedback control, an opportunity for electrode design to reduce trial and error, and an urgent imperative to improve the sustainability of manufacture

    Intercalibration of the barrel electromagnetic calorimeter of the CMS experiment at start-up

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    Calibration of the relative response of the individual channels of the barrel electromagnetic calorimeter of the CMS detector was accomplished, before installation, with cosmic ray muons and test beams. One fourth of the calorimeter was exposed to a beam of high energy electrons and the relative calibration of the channels, the intercalibration, was found to be reproducible to a precision of about 0.3%. Additionally, data were collected with cosmic rays for the entire ECAL barrel during the commissioning phase. By comparing the intercalibration constants obtained with the electron beam data with those from the cosmic ray data, it is demonstrated that the latter provide an intercalibration precision of 1.5% over most of the barrel ECAL. The best intercalibration precision is expected to come from the analysis of events collected in situ during the LHC operation. Using data collected with both electrons and pion beams, several aspects of the intercalibration procedures based on electrons or neutral pions were investigated
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