Home About us Contact
|
Home About us Contact | ||
|
|
||
Tremendous Number (tremendous + number)
Selected AbstractsA two-grid fictitious domain method for direct simulation of flows involving non-interacting particles of a very small sizeINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 11 2010A. Dechaume Abstract The full resolution of flows involving particles whose scale is hundreds or thousands of times smaller than the size of the flow domain is a challenging problem. A naive approach would require a tremendous number of degrees of freedom in order to bridge the gap between the two spatial scales involved. The approach used in the present study employs two grids whose grid size fits the two different scales involved, one of them (the micro-scale grid) being embedded into the other (the macro-scale grid). Then resolving first the larger scale on the macro-scale grid, we transfer the so obtained data to the boundary of the micro-scale grid and solve the smaller size problem. Since the particle is moving throughout the macro-scale domain, the micro-scale grid is fixed at the centroid of the moving particle and therefore moves with it. In this study we combine such an approach with a fictitious domain formulation of the problem resulting in a very efficient algorithm that is also easy to implement in an existing CFD code. We validate the method against existing experimental data for a sedimenting sphere, as well as analytical results for motion of an inertia-less ellipsoid in a shear flow. Finally, we apply the method to the flow of a high aspect ratio ellipsoid in a model of a human lung airway bifurcation. Copyright © 2009 John Wiley & Sons, Ltd. [source] Conformational search of peptides and proteins: Monte Carlo minimization with an adaptive bias method applied to the heptapeptide deltorphinJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 4 2004S. Banu Ozkan Abstract The energy function of a protein consists of a tremendous number of minima. Locating the global energy minimum (GEM) structure, which corresponds approximately to the native structure, is a severe problem in global optimization. Recently we have proposed a conformational search technique based on the Monte Carlo minimization (MCM) method of Li and Scheraga, where trial dihedral angles are not selected at random within the range [,180°,180°] (as with MCM) but with biased probabilities depending on the increased structure-energy correlations as the GEM is approached during the search. This method, called the Monte Carlo minimization with an adaptive bias (MCMAB), was applied initially to the pentapeptide Leu-enkephalin. Here we study its properties further by applying it to the larger peptide with bulky side chains, deltorphin (H-Tyr-D-Met-Phe-His-Leu-Met-Asp-NH2). We find that on average the number of energy minimizations required by MCMAB to locate the GEM for the first time is smaller by a factor of approximately three than the number required by MCM,in accord with results obtained for Leu-enkephalin. © 2004 Wiley Periodicals, Inc. J Comput Chem 25: 565,572, 2004 [source] Proton MRS of early post-natal mouse brain modifications in vivoNMR IN BIOMEDICINE, Issue 2 2006Pierre Larvaron Abstract NMR provides a non-invasive tool for the phenotypic characterisation of mouse models. The aim of the present study was to apply reliable in vivo MRS techniques for non-invasive investigations of brain development in normal and transgenic mice, by monitoring metabolite concentrations in different brain regions. The conditions of anaesthesia, immobilisation and respiratory monitoring were optimized to carry out in vivo MRS studies in young mice. All the experiments were performed in normal mice, at 9.4,T, applying a point-resolved spectroscopy (PRESS) sequence (TR,=,2000,ms; TE,=,130,ms). We obtained reproducible in vivo1H NMR spectra of wild-type mouse brains as early as post-natal day 5, which allowed us to follow brain maturation variations from post-natal days 5 to 21. The survival rate of animals was between 66 and 90% at post-natal days 5 and 21, respectively. Developmental changes of metabolite concentrations were measured in three brain regions: the thalamus, a region rich in cell bodies, the olfactory bulb, rich in fibre tracts actively myelinated during brain maturation, and the cerebellum. The voxel size varied from 2 to 8 µL according to the size of the brain structure analysed. The absolute concentrations of the total creatine, taurine, total choline, N -acetylaspartate and of the glutamate/glutamine pool were determined from 1H NMR spectra obtained in the different brain regions at post-natal day 5, 10, 15 and 21. Variations observed during brain development were in accordance with those previously reported in mice using ex vivo MRS studies, and also in rats and humans in vivo. Possibilities of longitudinal MRS analysis in maturing mice brains provide new perspectives to characterise better the tremendous number of transgenic mutant mice generated with the aim of decrypting the complexity of brain development and neurodegenerative diseases but also to follow the impact of environmental and therapeutic factors. Copyright © 2006 John Wiley & Sons, Ltd. [source] Hypersensitivity pneumonitis caused by Penicillium citrinum, not enoki sporesAMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 12 2007Sumiko Yoshikawa MD Abstract Background Flammulina velutipes is called the Enoki mushroom in Japanese and is cultivated indoors. Mushroom workers face occupational exposure to a tremendous number of fungi and organic antigens capable of causing hypersensitivity pneumonitis (HP). One worker employed at an Enoki farm developed HP due to Penicillium citrinum. This study investigated new cases of HP among the workers cultivating Enoki. Methods Serum Krebs von der Lungen-6 (KL-6), surfactant protein (SP)-A and SP-D were measured. Lymphocyte stimulation tests (LST) and double immunodiffusion tests (DIT) were performed to identify P. citrinum. Workers showing high levels of KL-6, SP-A, or SP-D and a high LST value or positive DIT were identified and then were further examined by chest computed tomography, bronchoalveolar lavage and transbronchial lung biopsy. The initial patient and new HP patients were defined as the HP group and the other participants were defined as the non-HP group. Results Forty-eight Enoki workers participated in the study. Four of nine workers who met the criteria for further examinations were diagnosed as having HP due to P. citrinum. In comparison between non-HP group and HP group, KL-6, SP-D and LST values were significantly higher in HP group. There was a strong correlation between KL-6 and SP-D. DIT had high sensitivity and high specificity. Conclusions KL-6, SP-D, LST, and DIT were useful for detecting HP patients. KL-6 was the most useful predictor of HP in this study. DIT was useful not only as a predictor of HP but also as a detector of the causative antigen. Am. J. Ind. Med. 50:1010,1017, 2007. © 2007 Wiley-Liss, Inc. [source] Developing an HIV cytotoxic T-lymphocyte vaccine: issues of CD8 T-cell quantity, quality and locationJOURNAL OF INTERNAL MEDICINE, Issue 1 2009D. Masopust Abstract. Issues of quantity, quality and location impact the ability of CD8 T cells to mediate protection from infection. These issues are considered in light of human immunodeficiency virus (HIV)/simian immunodeficiency virus (SIV) vaccination. Methods are reviewed that result in 100- to 1000-fold higher frequencies of vaccine-specific memory CD8 T cells than that achieved by current HIV/SIV vaccine approaches. Data demonstrating that location within mucosal tissues has a direct impact on memory CD8 T-cell function are discussed. Arguments are made that establishing memory CD8 T cells within mucosal sites of transmission, a priori to natural infection, may be essential for conferring optimal and rapid protection. Lastly, it is proposed that heterologous prime-boost vaccination with recombinant live replicating vectors, which has the potential to induce tremendous numbers of cytolytic memory CD8 T cells within mucosal tissues, would provide a far more stringent test of the hypothesis that memory CD8 T cells could, in principal, form the basis for a preventative HIV vaccine. [source] | ||||||||||