986 research outputs found

    Atypical one-carbon metabolism of an acetogenic and hydrogenogenic Moorella thermoacetica strain

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    A thermophilic spore-forming bacterium (strain AMP) was isolated from a thermophilic methanogenic bioreactor that was fed with cobalt-deprived synthetic medium containing methanol as substrate. 16S rRNA gene analysis revealed that strain AMP was closely related to the acetogenic bacterium Moorella thermoacetica DSM 521T (98.3% sequence similarity). DNA¿DNA hybridization showed 75.2 ± 4.7% similarity to M. thermoacetica DSM 521T, suggesting that strain AMP is a M. thermoacetica strain. Strain AMP has a unique one-carbon metabolism compared to other Moorella species. In media without cobalt growth of strain AMP on methanol was only sustained in coculture with a hydrogen-consuming methanogen, while in media with cobalt it grew acetogenically in the absence of the methanogen. Addition of thiosulfate led to sulfide formation and less acetate formation. Growth of strain AMP with CO resulted in the formation of hydrogen as the main product, while other CO-utilizing Moorella strains produce acetate as product. Formate supported growth only in the presence of thiosulfate or in coculture with the methanogen. Strain AMP did not grow with H2/CO2, unlike M. thermoacetica (DSM 521T). The lack of growth with H2/CO2 likely is due to the absence of cytochrome b in strain AM

    Accidents Will Happen. Do Safety Systems Improve Warehouse Safety Performance?

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    Safety is becoming more and more an issue in warehouses. In the literature, effective measures leading to increased occupational health and safety have hardly been researched. Most research focuses on the impact of perceived safety-related leadership of managers and worker safety consciousness on ‘safety climate’ and workers’ safe behavior. We have carried out exploratory research into which measures really improve the safety performance of a warehouse. We particularly focus on the effects of (1) safety-related work procedures, (2) safety leadership, and (3) workers’ safety consciousness. Based on a survey we show that safety leadership and safety-related work procedures significantly drive worker safety consciousness, which in turn positively impacts safety performance

    Tau Polarization in Λb→Xcτνˉ \Lambda_b \to X_c \tau \bar{\nu} and B→XcτνˉB \to X_c \tau \bar{\nu}

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    We discuss the longitudinal and transverse Ï„\tau-polarization in inclusive decays of hadrons containing bb-quarks. The calculation is performed by means of an OPE in HQET. Some mathematical difficulties in calculating transverse polarizations are explained. Numerical results are presented for longitudinal and for transverse polarizations, both in and perpendicular to the decay plane.Comment: LATEX, 20 pages, 5 Postscript figure

    Equilibrium solutions of the shallow water equations

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    A statistical method for calculating equilibrium solutions of the shallow water equations, a model of essentially 2-d fluid flow with a free surface, is described. The model contains a competing acoustic turbulent {\it direct} energy cascade, and a 2-d turbulent {\it inverse} energy cascade. It is shown, nonetheless that, just as in the corresponding theory of the inviscid Euler equation, the infinite number of conserved quantities constrain the flow sufficiently to produce nontrivial large-scale vortex structures which are solutions to a set of explicitly derived coupled nonlinear partial differential equations.Comment: 4 pages, no figures. Submitted to Physical Review Letter

    A heavy quark effective field lagrangian keeping particle and antiparticle mixed sectors

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    We derive a tree-level heavy quark effective Lagrangian keeping particle-antiparticle mixed sectors allowing for heavy quark-antiquark pair annihilation and creation. However, when removing the unwanted degrees of freedom from the effective Lagrangian one has to be careful in using the classical equations of motion obeyed by the effective fields in order to get a convergent expansion on the reciprocal of the heavy quark mass. Then the application of the effective theory to such hard processes should be sensible for special kinematic regimes as for example heavy quark pair production near threshold.Comment: LaTeX, 14 pages, 1 EPS figure

    Inclusive Semileptonic Decays in QCD Including Lepton Mass Effects

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    Starting from an Operator Product Expansion in the Heavy Quark Effective Theory up to order 1/m_b^2 we calculate the inclusive semileptonic decays of unpolarized bottom hadrons including lepton mass effects. We calculate the differential decay spectra d\Gamma/(dE_\tau ), and the total decay rate for B meson decays to final states containing a \tau lepton.Comment: 16 pages + 4 figs. appended in uuencoded form, LaTeX, MZ-TH/93-3

    Teaching Index Numbers to economists

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    Economic statistics are frequently reported in the form of index numbers. This article considers how the field of Index Numbers should be approached in the teaching of a general economic degree. While the topic finds a natural home in statistics modules, it is emphasised that the area can also be referred to in the teaching of other areas of economics. It is also emphasised that the differences between Index Numbers theory and the practice of compiling economic statistics such as inflation can help students gain a better understanding of applied economic statistics. Methods for assessing learning in the area are also considered and available material to support teaching is also summarised

    The Promising Process to Distinguish Supersymmetric Models with Large tanβ\beta from the Standard Model: B→Xsμ+μ−B\to X_s{\mu}^{+}{\mu}^{-}

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    It is shown that in supersymmetric models (SUSYMs) the large supersymmetric contributions to B→Xsμ+μ−B \to X_s{\mu}^{+}{\mu}^{-} come from the Feynman diagrams which consist of exchanging neutral Higgs bosons (NHBs) and the chargino-stop loop and are proportional to mbmμm_b m_{\mu}tan3β/mh2^3\beta/m_{h}^2 when tanβ\beta is large and the mass of the lightest neutral Higgs boson mh_h is not too large (say, less than 150 Gev). Numerical results show that the branching ratios of B→Xsμ+μ−B \to X_s{\mu}^{+}{\mu}^{-} can be enhanced by more than 100% compared to the standard model (SM) and the backward-forward asymmetry of lepton is significantly different from that in SM when tanβ≥30\beta \geq 30.Comment: 8 pages, including 2 figure
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