2,755 research outputs found

    Molecular mechanisms of adaptation of the moderately halophilic bacterium Halobacillis halophilus to its environment

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    The capability of osmoadaptation is a prerequisite of organisms that live in an environment with changing salinities. Halobacillus halophilus is a moderately halophilic bacterium that grows between 0.4 and 3 M NaCl by accumulating both chloride and compatible solutes as osmolytes. Chloride is absolutely essential for growth and, moreover, was shown to modulate gene expression and activity of enzymes involved in osmoadaptation. The synthesis of different compatible solutes is strictly salinity- and growth phase-dependent. This unique hybrid strategy of H. halophilus will be reviewed here taking into account the recently published genome sequence. Based on identified genes we will speculate about possible scenarios of the synthesis of compatible solutes and the uptake of potassium ion which would complete our knowledge of the fine-tuned osmoregulation and intracellular osmolyte balance in H. halophilus

    The Importance of Equity Finance for R&D Activity – Are There Differences Between Young and Old Companies?

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    This paper analyzes the importance of equity finance for the R&D activity of small and medium-sized enterprises. We use information on almost 6000 German SMEs from a company survey. Using the intensity of banking competition at the district level as instrument to control for endogeneity, we find that a higher equity ratio is conducive to more R&D for young but not for old companies. Equity may be a constraining factor for young companies which have to rely on the original equity investment of their owners since they have not yet accumulated retained earnings and can relay less on outside financing. The positive influence is found for R&D intensity but not for the decision whether to perform R&D. Equity financing is therefore especially important for the most innovative, young companies.R&D activity; equity finance; small and medium-sized enterprises

    Manche mögen’s salzig : Anpassungsstrategien und Biotechnologie Salz liebender Mikroorganismen

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    Sie lieben extreme Bedingungen: Einige leben in tiefen Gesteinsschichten oder ohne Licht und Sauerstoff an kochend heißen Quellen der Tiefsee, andere bevorzugen die eisigen Temperaturen der Polargebiete, und wieder andere fühlen sich erst richtig wohl in kochender Schwefelsäure. Doch wie passen sich Mikroorganismen an diese extremen Bedingungen an? Die Forschung hat darauf bereits Antworten gefunden, die sich auch biotechnologisch nutzen lassen

    Large scale environmental bias of the QSO line of sight proximity effect

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    We analyse the proximity zone of the intergalactic matter around high-redshift quasars in a cosmological environment. In a box of 64 h-1 Mpc base length we employ dark matter only simulations. For estimating the hydrogen temperature and density distribution we use the effective equation of state. Hydrogen is assumed to be in photoionisation equilibrium with a model background flux which is fit to recent observations of the mean optical depth and transmission flux statistics. At redshifts z = 3, 4, and 4.8, we select model quasar positions at the centre of the 20 most massive halos and 100 less massive halos identified in the simulation. From each assumed quasar position we cast 100 random lines of sight for two box length including the changes in the ionisation fractions by the QSO flux field and derive mock Ly{\alpha} spectra. The proximity effect describes the dependence of the mean normalised optical depth {\xi} = {\tau}eff, QSO/{\tau}eff, Ly{\alpha} as a function of the ratio of the ionisation rate by the QSO and the background field, {\omega} = {\Gamma}QSO/{\Gamma}UVB, i.e. the profile {\xi} = (1 + {\omega}/a)-0.5, where a strength parameter a is introduced. The strength parameter measures the deviation from the theoretical background model and is used to quantify any influence of the environmental density field. We reproduce an unbiased measurement of the proximity effect which is not affected by the host halo mass. The scatter between different lines of sight and different quasar host positions increases with decreasing redshift. Around the host halos, we find only a slight average overdensity in the proximity zone at comoving radii of 1 < rc < 10h-1 Mpc. However, a clear power-law correlation of the strength parameter with the average overdensity in rc is found, showing an overestimation of the ionising background in overdense regions and an underestimation in underdense regions.Comment: Accepted by Monthly Notices of the Royal Astronomical Society. 15 pages, 12 figure
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