197,184 research outputs found

    Preparation of Neurospora crassa mitochondria

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    The fungus Neurospora crassa represents a eukaryotic cell with high biosynthetic activities. Cell mass doubles in 2-4 hr during expone ntial growth , even in simple salt media with sucrose as the sole carbon source. The microorgani sm forms a mycelium of long hyphae durlng vegetative growth . The mitochondria can be isolated under relatively gentle condi tions since a few breaks in the threadlike hyphae are sufficient to cause the outflow of the organelles. This article describes two methods for the physical disruption of the hyphae : (I) The cell s are opened in a grind mill between two rotating corundum di sks. This is a continuous and fast procedure and allows large- and small-scale preparations of mitochondria. (2) Hyphae are ground with sand in a mortar and pestle. This procedure can be applied to microscale preparations of mitochondria starting with minute amounts of cells. Other procedures for the isolation of Neurospora mitochondria after the physical di sruption or the enzymatic degradation of the cell wall have been described elsewher

    A folk Quillen model structure for operads

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    We establish, by elementary means, the existence of a cofibrantly generated monoidal model structure on the category of operads. By slicing over a suitable operad the classical Rezk model structure on the category of small categories is recovered

    The real numbers - a survey of constructions

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    We present a comprehensive survey of constructions of the real numbers (from either the rationals or the integers) in a unified fashion, thus providing an overview of most (if not all) known constructions ranging from the earliest attempts to recent results, and allowing for a simple comparison-at-a-glance between different constructions

    Labor Law and the Assumption of Risk

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    Measuring success of open source projects using web search engines

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    What makes an open source project successful? In this paper we show that the traditional factors of success of open source projects, such as number of downloads, deployments or commits are sometimes inconvenient or even insufficient. We then correlate success of an open source project with its popularity on the Web. We show several ideas of how such popularity could be measured using Web search engines and provide experimental results from quantitative analysis of the proposed measures on representative large samples of open source projects from SourceForge
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