828 research outputs found

    Sputtering ion source Final report, 29 Mar. - 30 Sep. 1963

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    Modified sputtering ion source analyses of solid

    Comment on: ``Trace anomaly of dilaton coupled scalars in two dimensions''

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    The trace anomaly for nonminimally coupled scalars in spherically reduced gravity obtained by Bousso and Hawking (hep-th/9705236) is incorrect. We explain the reasons for the deviations from our correct (published) result which is supported by several other recent papers.Comment: 2 page

    Electromagnetic Polarizabilities and Charge Radii of the Nucleons in the Diquark-model

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    The diquark model is used to calculate the electromagnetic polarizabilities and charge radii of the nucleons for three different potentials. Making the scalar diquark lower in mass introduces a mixing angle θ\theta between the ∣56⟩\left| 56\right\rangle and ∣70⟩\left| 70\right\rangle states ,which allows an improvement in value of all 6 properties. Generalizing the Gamov-Teller matrix and the magnetic moment operator to the diquark model gives constraints on this mixing. We obtain for the Richardson potential θ=23.2∘,\theta =23.2^{\circ }, α‾p=7.9−0.9+1.0×10−4fm3,\overline{\alpha }_p=7.9_{-0.9}^{+1.0}\times 10^{-4}fm^3, α‾n=7.7−0.6+0.3×10−4fm3,\overline{\alpha }_n=7.7_{-0.6}^{+0.3}\times 10^{-4}fm^3, β‾p=5.4−0.4+1.6×10−4fm3,\overline{\beta }_p=5.4_{-0.4}^{+1.6}\times 10^{-4}fm^3, β‾n=6.7−0.7+1.3×10−4fm3,\overline{\beta }% _n=6.7_{-0.7}^{+1.3}\times 10^{-4}fm^3, ⟨r2⟩p=0.37−0.03+0.02fm2,\left\langle r^2\right\rangle _p=0.37_{-0.03}^{+0.02}fm^2, ⟨r2⟩n=−0.07−0.02+0.03fm2.\left\langle r^2\right\rangle _n=-0.07_{-0.02}^{+0.03}fm^2. Additional pion cloud contributions could improve on all six results.Comment: 15 Pages, Latex, Figs on request, to be published Phys.Lett.B. Minor errors corrected and eqn 5,6,8,9 correcte

    Secretion of Streptomyces mobaraensis pro-transglutaminase by coryneform bacteria

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    We previously reported on the secretion of Streptomyces mobaraensis transglutaminase by Corynebacterium glutamicum ATCC13869 (formerly classified as Brevibacterium lactofermentum). In the present work, we investigated whether any other coryneform bacteria showed higher productivity than C. glutamicum ATCC13869. We found that most coryneform species secreted pro-transglutaminase efficiently. Moreover, we confirmed that Corynebacterium ammoniagenes ATCC6872 produced about 2.5 g/l pro-transglutaminase over a 71-h period in a jar fermentor. Our findings suggest that some other coryneform bacteria, especially C. ammoniagenes ATCC6872, are potential hosts for industrial scale protein production

    Thermodynamics of Black Holes in Two (and Higher) Dimensions

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    A comprehensive treatment of black hole thermodynamics in two-dimensional dilaton gravity is presented. We derive an improved action for these theories and construct the Euclidean path integral. An essentially unique boundary counterterm renders the improved action finite on-shell, and its variational properties guarantee that the path integral has a well-defined semi-classical limit. We give a detailed discussion of the canonical ensemble described by the Euclidean partition function, and examine various issues related to stability. Numerous examples are provided, including black hole backgrounds that appear in two dimensional solutions of string theory. We show that the Exact String Black Hole is one of the rare cases that admits a consistent thermodynamics without the need for an external thermal reservoir. Our approach can also be applied to certain higher-dimensional black holes, such as Schwarzschild-AdS, Reissner-Nordstrom, and BTZ.Comment: 63 pages, 3 pdf figures, v2: added reference

    The Human Fungal Pathogen Cryptococcus neoformans Escapes Macrophages by a Phagosome Emptying Mechanism That Is Inhibited by Arp2/3 Complex-Mediated Actin Polymerisation

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    The lysis of infected cells by disease-causing microorganisms is an efficient but risky strategy for disseminated infection, as it exposes the pathogen to the full repertoire of the host's immune system. Cryptococcus neoformans is a widespread fungal pathogen that causes a fatal meningitis in HIV and other immunocompromised patients. Following intracellular growth, cryptococci are able to escape their host cells by a non-lytic expulsive mechanism that may contribute to the invasion of the central nervous system. Non-lytic escape is also exhibited by some bacterial pathogens and is likely to facilitate long-term avoidance of the host immune system during latency. Here we show that phagosomes containing intracellular cryptococci undergo repeated cycles of actin polymerisation. These actin ‘flashes’ occur in both murine and human macrophages and are dependent on classical WASP-Arp2/3 complex mediated actin filament nucleation. Three dimensional confocal imaging time lapse revealed that such flashes are highly dynamic actin cages that form around the phagosome. Using fluorescent dextran as a phagosome membrane integrity probe, we find that the non-lytic expulsion of Cryptococcus occurs through fusion of the phagosome and plasma membranes and that, prior to expulsion, 95% of phagosomes become permeabilised, an event that is immediately followed by an actin flash. By using pharmacological agents to modulate both actin dynamics and upstream signalling events, we show that flash occurrence is inversely related to cryptococcal expulsion, suggesting that flashes may act to temporarily inhibit expulsion from infected phagocytes. In conclusion, our data reveal the existence of a novel actin-dependent process on phagosomes containing cryptococci that acts as a potential block to expulsion of Cryptococcus and may have significant implications for the dissemination of, and CNS invasion by, this organism.\ud \u
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