631 research outputs found

    Mesh deformation with exact surface reconstruction using a reduced radial basis function approach

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    This paper presents a novel reduced radial basis function approach with exact surface reconstruction. The new approach combines two well proven mesh deformation algorithms in a three step approach. In a first pre-processing step an explicit reduction of radial basis function points is performed using a k-d tree. In the second step the classic radial basis function interpolation is used to propagate the deformation field. In a last post-processing step an exact surface reconstruction is achieved using an efficient Delaunay graph mapping approach. The new mesh deformation approach is compared to the two original approaches by investigating a 2D viscous mesh test case. The applicability of the new approach to 3D is shown via an aeroelastic relevant wing test case

    Electron-Phonon Dynamics in an Ensemble of Nearly Isolated Nanoparticles

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    We investigate the electron population dynamics in an ensemble of nearly isolated insulating nanoparticles, each nanoparticle modeled as an electronic two-level system coupled to a single vibrational mode. We find that at short times the ensemble-averaged excited-state population oscillates but has a decaying envelope. At long times, the oscillations become purely sinusoidal about a ``plateau'' population, with a frequency determined by the electron-phonon interaction strength, and with an envelope that decays algebraically as t^-{1/2} We use this theory to predict electron-phonon dynamics in an ensemble of Y_2 O_3 nanoparticles.Comment: 11 pages, 3 figure

    Inflation driven by scalar field with non-minimal kinetic coupling with Higgs and quadratic potentials

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    We study a scalar field with non-minimal kinetic coupling to itself and to the curvature. The slow rolling conditions allowing an inflationary background have been found. The quadratic and Higgs type potentials have been considered, and the corresponding values for the scalar fields at the end of inflation allows to recover the connection with particle physics.Comment: 16 pages, to appear in JCA

    Enhancing Production of Recombinant Proteins from Mammalian Cells

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    The bio-manufacturing of recombinant proteins from mammalian cell cultures requires robust processes that can maximize protein yield while ensuring the efficacy of these proteins as human therapeutics. Recognizing that the challenge of improving protein yield and quality can be met through various approaches, this paper presents three strategies currently being developed in our group. A method for rapidly selecting subpopulations of cells with high production characteristics is proposed. This method combines the efficiency of green fluorescent protein/fluorescence-activated cell sorting (GFP/FACS)–based screening with homologous recombination to generate and select high-producing subclones. Next, the development of chemically defined, protein-free media for enhancing monoclonal antibody production is described. Analysis of culture media effects on the genome-wide transcriptional program of the cell is presented as a means to optimize the culture media and identify potential targets for genetic manipulation. Finally, we propose a method for increasing the extent of intracellular sialylation by improving the transport of CMP-sialic acid into the trans-Golgi. This is hypothesized to increase the sialic acid availability, and may enhance the degree of sialylation in the glycoprotein product.Singapore-MIT Alliance (SMA

    The development of metaphorical language comprehension in typical development and in Williams syndrome

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    The domain of figurative language comprehension was used to probe the developmental relation between language and cognition in typically developing individuals and individuals with Williams syndrome. Extending the work of Vosniadou and Ortony, the emergence of nonliteral similarity and category knowledge was investigated in 117 typically developing children between 4 and 12 years of age, 19 typically developing adults, 15 children with Williams syndrome between 5 and 12 years of age, and 8 adults with Williams syndrome. Participants were required to complete similarity and categorization statements by selecting one of two words (e.g., either The sun is like ___ or The sun is the same kind of thing as ___ ) with word pairs formed from items that were literally, perceptually, or functionally similar to the target word or else anomalous (e.g., moon, orange, oven, or chair, respectively). Results indicated that individuals with Williams syndrome may access different, less abstract knowledge in figurative language comparisons despite the relatively strong verbal abilities found in this disorder. © 2010 Elsevier Inc. All rights reserved

    The development of metaphorical language comprehension in typical development and in Williams syndrome

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    The domain of figurative language comprehension was used to probe the developmental relation between language and cognition in typically developing individuals and individuals with Williams syndrome. Extending the work of Vosniadou and Ortony, the emergence of nonliteral similarity and category knowledge was investigated in 117 typically developing children between 4 and 12 years of age, 19 typically developing adults, 15 children with Williams syndrome between 5 and 12 years of age, and 8 adults with Williams syndrome. Participants were required to complete similarity and categorization statements by selecting one of two words (e.g., either “The sun is like ___” or “The sun is the same kind of thing as ___”) with word pairs formed from items that were literally, perceptually, or functionally similar to the target word or else anomalous (e.g., moon, orange, oven, or chair, respectively). Results indicated that individuals with Williams syndrome may access different, less abstract knowledge in figurative language comparisons despite the relatively strong verbal abilities found in this disorder

    Corrigendum: Hearing impairment is associated with smaller brain volume in aging

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    In the original article, Roshchupkin et al. (2016) was not cited in the article. The citation has now been inserted in Materials and Methods, subsection Brain MRI Acquisition and Processing, second paragraph and should read: Voxel based morphometry (VBM) was performed according to an optimized VBM protocol (Good et al., 2001) and was previously described (Roshchupkin et al., 2016). FSL software (Smith et al., 2004) was used for VBM data processing, all GM and WM density maps were non-linearly registered to the standard ICBM MNI152 GM and WM template (Montreal Neurological Institute) with a 1 mm Ă— 1 mm Ă— 1 mm voxel resolution. Subsequently, a spatial modulation and smoothing procedure with 3 mm (FWHM 8 mm) isotropic Gaussian kernel were applied to all images. The authors apologize for this error and state that this does not change the scientific conclusions of the article in any way. Conflict of Interest Statement The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest

    Effects of H2O2 on growth, metabolic activity and membrane integrity in three strains of Microcystis aeruginosa.

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    The application of hydrogen peroxide (H2O2) as a management tool to control Microcystis blooms has become increasingly popular due to its short lifetime and targeted action. H2O2 increases intracellular reactive oxygen species resulting in oxidative stress and subsequently cell death. H2O2 is naturally produced in freshwater bodies as a result of photocatalytic reactions between dissolved organic carbon and sunlight. Previously, some studies have suggested that this environmental source of H2O2 selectively targets for toxigenic cyanobacteria strains in the genus Microcystis. Also, past studies only focused on the morphological and biochemical changes of H2O2-induced cell death in Microcystis with little information available on the effects of different H2O2 concentrations on growth, esterase activity and membrane integrity. Therefore, this study investigated the effects of non-lethal (40-4000 nM) concentrations on percentage cell death; with a focus on sub-lethal (50 μM) and lethal (275 μM; 500 μM) doses of H2O2 on growth, cells showing esterase activity and membrane integrity. The non-lethal dose experiment was part of a preliminary study. Results showed a dose- and time-dependent relationship in all three Microcystis strains post H2O2 treatment. H2O2 resulted in a significant increase in intracellular reactive oxygen species, decreased chlorophyll a content, decreased growth rate and esterase activity. Interestingly, at sub-lethal (50 μM H2O2 treatment), percentage of dead cells in microcystin-producing strains was significantly higher (p < 0.05) than that in non-microcystin-producing strains at 72 h. These findings further cement our understanding of the influence of H2O2 on different strains of Microcystis and its impact on membrane integrity and metabolic physiology: important to future toxic bloom control programmes

    Engineering Mammalian Cells for Improved Recombinant Protein Production

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    The production of recombinant glycoproteins from mammalian cell cultures requires robust processes that can achieve high protein yield while ensuring the efficacy of these proteins as human therapeutics. We describe two approaches currently being developed in our group to genetically engineer cell lines with desirable characteristics for recombinant protein production. To enhance the degree of sialylation in the glycoprotein product, we propose to increase intracellular sialic acid availability by overexpressing the CMP-sialic acid transporters. We are also interested in engineering mammalian cells that can proliferate at reduced cultivation temperatures. Low temperature cultivation of mammalian cells has been shown to enhance glycoprotein production but reduces cell growth. It is hypothesized that a mutant cell line that can proliferate at low temperatures may be coupled with low temperature cultivation to improve recombinant protein production.Singapore-MIT Alliance (SMA

    NOD.c3c4 congenic mice develop autoimmune biliary disease that serologically and pathogenetically models human primary biliary cirrhosis

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    Primary biliary cirrhosis (PBC) is an autoimmune disease with a strong genetic component characterized by biliary ductular inflammation with eventual liver cirrhosis. The serologic hallmark of PBC is antimitochondrial antibodies that react with the pyruvate dehydrogenase complex, targeting the inner lipoyl domain of the E2 subunit (anti–PDC-E2). Herein we demonstrate that NOD.c3c4 mice congenically derived from the nonobese diabetic strain develop an autoimmune biliary disease (ABD) that models human PBC. NOD.c3c4 (at 9–10 wk, before significant biliary pathology) develop antibodies to PDC-E2 that are specific for the inner lipoyl domain. Affected areas of biliary epithelium are infiltrated with CD3+, CD4+, and CD8+ T cells, and treatment of NOD.c3c4 mice with monoclonal antibody to CD3 protects from ABD. Furthermore, NOD.c3c4-scid mice develop disease after adoptive transfer of splenocytes or CD4+ T cells, demonstrating a central role for T cells in pathogenesis. Histological analysis reveals destructive cholangitis, granuloma formation, and eosinophilic infiltration as seen in PBC, although, unlike PBC, the extrahepatic biliary ducts are also affected. Using a congenic mapping approach, we define the first ABD (Abd) locus, Abd1. These results identify the NOD.c3c4 mouse as the first spontaneous mouse model of PBC
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