1,183 research outputs found

    Growth and calorific approximation in the speckled trout (Salvelinus fontinalis)

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    From the point of view of energy metabolism, appropriate measures of the rate of oxygen uptake would indicate the energy turnover or the capacity of the organism to perform external work in relation to its size and under the prevalent environmental conditions. Estimates of oxygen uptake when considered in conjunction with growth rate and calorific equivalent of the metabolic rate, would permit estimates of the total energy requirements of the individual. It has long been established, that the calorific equivalent of food consumed corresponds to the heat output plus the heat equivalent of excreta, and that such a measurement of metabolism can be verified also by indirect calorimetric methods based on the gas exchange of the animal

    Constrained RS coding for Low Peak to Average Power Ratio in FBMC -- OQAM Systems

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    Multi-carrier modulation techniques have now become a standard in many communication protocols. Filter bank based multi-carrier (FBMC) generation techniques have been discussed in the literature as a means for overcoming the shortcomings of IFFT/FFT based OFDM system. The Peak to Average Power Ratio (PAPR) is a problem faced by all multi-carrier techniques. This paper discusses the methods for reducing PAPR in a FBMC system while maintaining acceptable Bit Error Rate (BER). A new PAPR minimizing scheme called Constrained Reed Solomon (CRS) coding is proposed. The hybrid techniques using coding and companding are tested for different channel models and is found to yield promising results.Comment: 6 pages,6 Figures, Journal of Electrical and Electronics Engineerin

    The potentiality of leather as alternative material for sustaining mask production in Ghana

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    This study explored the viability of the Ghanaian indigenous vegetable tanned leather for the production of aesthetic masks for ornamental purposes. The study was basically experimental, and all processes were observed and recorded carefully for analysis. Modeling technique was principally used in three experiments to produce masks with three different thicknesses of leather acquired from cow hides. The thicknesses were purposively selected. The outcome of the study has confirmed the versatility of leather as alternative material for mask production. The study has strategically created another impetus in diversifying and expanding the utility of Ghanaian indigenous vegetable tanned leather aside the conventional usage for making bags, sandals and footrests. Keywords: Leather, Mask, Alternative Material, Sustainabilit

    Experimental evidence of shock mitigation in a Hertzian tapered chain

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    We present an experimental study of the mechanical impulse propagation through a horizontal alignment of elastic spheres of progressively decreasing diameter ϕn\phi_n, namely a tapered chain. Experimentally, the diameters of spheres which interact via the Hertz potential are selected to keep as close as possible to an exponential decrease, ϕn+1=(1q)ϕn\phi_{n+1}=(1-q)\phi_n, where the experimental tapering factor is either q15.60q_1\simeq5.60~% or q28.27q_2\simeq8.27~%. In agreement with recent numerical results, an impulse initiated in a monodisperse chain (a chain of identical beads) propagates without shape changes, and progressively transfer its energy and momentum to a propagating tail when it further travels in a tapered chain. As a result, the front pulse of this wave decreases in amplitude and accelerates. Both effects are satisfactorily described by the hard spheres approximation, and basically, the shock mitigation is due to partial transmissions, from one bead to the next, of momentum and energy of the front pulse. In addition when small dissipation is included, a better agreement with experiments is found. A close analysis of the loading part of the experimental pulses demonstrates that the front wave adopts itself a self similar solution as it propagates in the tapered chain. Finally, our results corroborate the capability of these chains to thermalize propagating impulses and thereby act as shock absorbing devices.Comment: ReVTeX, 7 pages with 6 eps, accepted for Phys. Rev. E (Related papers on http://www.supmeca.fr/perso/jobs/

    How Hertzian solitary waves interact with boundaries in a 1-D granular medium

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    We perform measurements, numerical simulations, and quantitative comparisons with available theory on solitary wave propagation in a linear chain of beads without static preconstrain. By designing a nonintrusive force sensor to measure the impulse as it propagates along the chain, we study the solitary wave reflection at a wall. We show that the main features of solitary wave reflection depend on wall mechanical properties. Since previous studies on solitary waves have been performed at walls without these considerations, our experiment provides a more reliable tool to characterize solitary wave propagation. We find, for the first time, precise quantitative agreements.Comment: Proof corrections, ReVTeX, 11 pages, 3 eps (Focus and related papers on http://www.supmeca.fr/perso/jobs/

    Role of tyrosine 238 in the active site of Rhodotorula gracilis D-amino acid oxidase - A site-directed mutagenesis study

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    Y238, one of the very few conserved residues in the active site of d-amino acid oxidases (DAAO), was mutated to phenylalanine and serine in the enzyme from the yeast Rhodotorula gracilis. The mutated proteins are catalytically competent thus eliminating Tyr238 as an active-site acid/base catalyst. Y238F and Y238S mutants exhibit a threefold slower turnover on d-alanine as substrate, which can be attributed to a slower rate of product release relative to the wild-type enzyme (a change of the rate constants for substrate binding was also evident). The Y238 DAAO mutants have spectral properties similar to those of the wild-type enzyme but the degree of stabilization of the flavin semiquinone and the redox properties in the free form of Y238S are different. The binding of the carboxylic acid competitive inhibitors and the substrate d-alanine are changed only slightly, suggesting that the overall substrate binding pocket remains intact. In agreement with data from the pH dependence of ligand binding and with the protein crystal structure, site-directed mutagenesis results emphasize the importance of residue Y238 in controlling access to the active site instead of a role in the substrate/ligand interaction

    The metabolism of Plotosus anguillaris (Bloch) in various concentrations of salt and oxygen in the medium

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    A matter which is of interest in fisheries both from the industrial and kientific points of view is the ability of fish and other animals to migrate from sea to freshwater and vice versa. In spite of the attention which this field of research has claimed, much $ill remains to be explained. The nature of the adaptive processes that the individual undertakes is not fully know

    Wave localization in strongly nonlinear Hertzian chains with mass defect

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    We investigate the dynamical response of a mass defect in a one-dimensional non-loaded horizontal chain of identical spheres which interact via the nonlinear Hertz potential. Our experiments show that the interaction of a solitary wave with a light intruder excites localized mode. In agreement with dimensional analysis, we find that the frequency of localized oscillations exceeds the incident wave frequency spectrum and nonlinearly depends on the size of the intruder and on the incident wave strength. The absence of tensile stress between grains allows some gaps to open, which in turn induce a significant enhancement of the oscillations amplitude. We performed numerical simulations that precisely describe our observations without any adjusting parameters.Comment: 4 pages, 5 figures, submitted for publicatio
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