1,794 research outputs found

    The lipid composition and its alteration during the growth stage in pathogenic fungus, epidermophyton floccosum

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    Qualitative and quantitative changes of lipid components during the growth stages were studied in E. floccosum. The acyl group components of total lipids of Trichophyton rubrum and Microsporum cookei were also examined. The lipids of E. floccosum amounted to approximately 4% of the dry cell weight. Neutral lipids mainly consisted of triglycerides and sterols, and major polar lipids were phosphatidylcholine, phosphatidylethanolamine, and an unknown lipid X. The fatty acids in tryglycerides and phospholipids were palmitic, palmitoleic, stearic, oleic, and linoleic acids. The unknown polar lipid X which appeared between phosphatidylethanolamine and cardiolipin on thin layer chromatography plates contained no phosphorus. There was no significant change in the fatty acid components of E. floccosum and T. rubrum during the cell growth, whereas profound changes occurred in M. cookei. The sterol components of E. floccosum showed striking changes depending on the growth stage

    Scaling Laws in High-Energy Inverse Compton Scattering. II. Effect of Bulk Motions

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    We study the inverse Compton scattering of the CMB photons off high-energy nonthermal electrons. We extend the formalism obtained by the previous paper to the case where the electrons have non-zero bulk motions with respect to the CMB frame. Assuming the power-law electron distribution, we find the same scaling law for the probability distribution function P_{1,K}(s) as P_{1}(s) which corresponds to the zero bulk motions, where the peak height and peak position depend only on the power-index parameter. We solved the rate equation analytically. It is found that the spectral intensity function also has the same scaling law. The effect of the bulk motions to the spectral intensity function is found to be small. The present study will be applicable to the analysis of the X-ray and gamma-ray emission models from various astrophysical objects with non-zero bulk motions such as radio galaxies and astrophysical jets.Comment: 10 pages, 3 figures, accepted version by Physical Review

    Preliminary observations on cage culture of Tilapia esculenta Graham and Tilapia xillii (Gervais) in Lake Victoria waters, at the Freshwater Fisheries Institute, Nyegezi, Tanzania

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    Cage culture of Tilapia is not suggested as a substitute for any known techniques in fish culture, but as one of the various techniques of obtaining more fish under controlled conditions. This fact has been very well accepted in various countries. Whererever facilities exist, this line of fish culture should be vigorously explored as a possible avenue in increasing fish production. High density stocking, management under controlled conditions, easy technique of fabricating the cage at relatively low cost, having no demand on land area, absence of prolific and effective breeding and easy availability of fish when a person needs it are a few of the attractions of the technique. The studies indicate that it is desirable to have different meshes for the cages, such as, small meshed cages for rearing fry to fingerlings stages, and larger meshed cages for rearing fingerlings to table sized fishes. II' the meshes are small, the resistance will be more and less water wilt pass through. While feeding with powdered food material, because of brisk activity of feeding fish, a part of the feed appeared wasted. This can be easily overcome if we would resort to feeding fish with cheap pelleted feeds which will no doubt reduce wastage. Precaution has to be taken against damage of the net and thereby loss of fish and against poaching by unauthorised persons. In the present attempt has been demonstrated the possibility of utilizing locally available species of Tilapia for cage culture and obtaining moderately satisfactory growth rates

    Isolation of endophytic bacteria from arboreal species of the Amazon and identification by sequencing of the 16S rRNA encoding gene

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    Endophytic bacteria from three arboreal species native to the Amazon (Carapa guianenses, Ceiba pentandra, and Swietenia macrophylla), were isolated and identified, through partial sequencing of the 16S rRNA encoding gene. From these, 16 isolates were obtained, although, when compared to sequences deposited in GenBank, only seven had produced identifiable fragments. Bacillus, Pantoea and two non-culturable samples were identified. Results obtained through sequence analysis revealed low genetic diversity across the isolates, even when analyzing different species and plant structures. This is the first report concerning the isolation and identification of endophytic bacteria in these plant species

    Effect of Nitrate, Acetate and Hydrogen on Native Perchlorate-reducing Microbial Communities and Their Activity in Vadose Soil

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    The effect of nitrate, acetate, and hydrogen on native perchlorate-reducing bacteria (PRB) was examined by conducting microcosm tests using vadose soil collected from a perchlorate-contaminated site. The rate of perchlorate reduction was enhanced by hydrogen amendment and inhibited by acetate amendment, compared with unamendment. Nitrate was reduced before perchlorate in all amendments. In hydrogen-amended and unamended soils, nitrate delayed perchlorate reduction, suggesting that the PRB preferentially use nitrate as an electron acceptor. In contrast, nitrate eliminated the inhibitory effect of acetate amendment on perchlorate reduction and increased the rate and the extent, possibly because the preceding nitrate reduction/denitrification decreased the acetate concentration that was inhibitory to the native PRB. In hydrogen-amended and unamended soils, perchlorate reductase gene (pcrA) copies, representing PRB densities, increased with either perchlorate or nitrate reduction, suggesting that either perchlorate or nitrate stimulates the growth of the PRB. In contrast, in acetate-amended soil pcrA increased only when perchlorate was depleted: a large portion of the PRB may have not utilized nitrate in this amendment. Nitrate addition did not alter the distribution of the dominant pcrA clones in hydrogen-amended soil, likely because of the functional redundancy of PRB as nitrate-reducers/denitrifiers, whereas acetate selected different pcrA clones from those with hydrogen amendment

    Ultraviolet television data from the Orbiting Astronomical Observatory. 1: Instrumentation and analysis techniques for the celescope experiment

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    The celescope instrumentation and data analysis system is described, the major problems encountered during orbital operation are summerized, and a few major problems that were anticipated but did not materialize are listed

    Generalized Misner-Sharp quasi-local mass in Einstein-Gauss-Bonnet gravity

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    We investigate properties of a quasi-local mass in a higher-dimensional spacetime having symmetries corresponding to the isomertries of an (n2)(n-2)-dimensional maximally symmetric space in Einstein-Gauss-Bonnet gravity in the presence of a cosmological constant. We assume that the Gauss-Bonnet coupling constant is non-negative. The quasi-local mass was recently defined by one of the authors as a counterpart of the Misner-Sharp quasi-local mass in general relativity. The quasi-local mass is found to be a quasi-local conserved charge associated with a locally conserved current constructed from the generalized Kodama vector and exhibits the unified first law corresponding to the energy-balance law. In the asymptotically flat case, it converges to the Arnowitt-Deser-Misner mass at spacelike infinity, while it does to the Deser-Tekin and Padilla mass at infinity in the case of asymptotically AdS. Under the dominant energy condition, we show the monotonicity of the quasi-local mass for any kk, while the positivity on an untrapped hypersurface with a regular center is shown for k=1k=1 and for k=0k=0 with an additional condition, where k=±1,0k=\pm1,0 is the constant sectional curvature of each spatial section of equipotential surfaces. Under a special relation between coupling constants, positivity of the quasi-local mass is shown for any kk without assumptions above. We also classify all the vacuum solutions by utilizing the generalized Kodama vector. Lastly, several conjectures on further generalization of the quasi-local mass in Lovelock gravity are proposed.Comment: 13 pages, no figures, 1 table; v4, new results added in the asymptotically AdS case, accepted for publication in Physical Review

    Energy Extraction from Higher Dimensional Black Holes and Black Rings

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    We analyze the energy extraction by the Penrose process in higher dimensions. Our result shows the efficiency of the process from higher dimensional black holes and black rings can be rather high compared with than that in four dimensional Kerr black hole. In particular, if one rotation parameter vanishes, the maximum efficiency becomes infinitely large because the angular momentum is not bounded from above. We also apply a catastrophe theory to analyze the stability of black rings. It indicates a branch of black rings with higher rotational energy is unstable, which should be a different type of instability from the Gregory-Laflamme's one.Comment: 11 pages, 7 figure

    Dynamical model for Pion - Nucleon Bremsstrahlung

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    A dynamical model based on effective Lagrangians is proposed to describe the bremsstrahlung reaction πNπNγ \pi N \to \pi N \gamma at low energies. The Δ(1232)\Delta(1232) degrees of freedom are incorporated in a way consistent with both, electromagnetic gauge invariance and invariance under contact transformations. The model also includes the initial and final state rescattering of hadrons via a T-matrix with off-shell effects. The πNγ\pi N \gamma differential cross sections are calculated using three different T-matrix models and the results are compared with the soft photon approximation, and with experimental data. The aim of this analysis is to test the off-shell behavior of the different T-matrices under consideration.Comment: 16 pages, latex, 6 eps figures. Accepted for publication in Physical Review
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