5,938 research outputs found

    A Strategy for Partnering in the Public Sector

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    Partnering is a cooperative approach to contract management that reduces costs, litigation, and stress. The Portland District of the Corps of Engineers has successfully used partnering as a formal management strategy. This paper presents an overview of the partnering strategy

    The generation of images of surface structures by laser-accelerated protons

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    Ion acceleration by lasers is one of the most important innovations in laser-plasma research in recent years. A mechanism that has gained great attention due to the remarkable properties of the accelerated beam is laser acceleration of protons from the rear surface of solid targets. A striking prediction is that these protons are capable of generating images of micro-structures present on this surface. These images might be useful to measure properties of the accelerated beam. In this article, we address the physics of the generation of images of surface structures imprinted into the target back surface with laser-accelerated protons

    Efficient molecular cloning of environmental DNA from geothermal sediments

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    An efficient and simple method for constructing an environmental library using mechanically sheared DNA obtained directly from geothermal sediments is presented. The method is based on blunt-end modification of DNA fragments followed by 3' -adenylation using Vent DNA polymerase and Taq DNA polymerase, respectively. The prepared DNA fragments are then ligated into a TA cloning vector and used in the transformation of Escherichia coli. This method has been successfully applied to the cloning of ORFs derived from uncultivated prokaryotes present in geothermal sediment

    Spectral Control via Multi-Species Effects in PW-Class Laser-Ion Acceleration

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    Laser-ion acceleration with ultra-short pulse, PW-class lasers is dominated by non-thermal, intra-pulse plasma dynamics. The presence of multiple ion species or multiple charge states in targets leads to characteristic modulations and even mono-energetic features, depending on the choice of target material. As spectral signatures of generated ion beams are frequently used to characterize underlying acceleration mechanisms, thermal, multi-fluid descriptions require a revision for predictive capabilities and control in next-generation particle beam sources. We present an analytical model with explicit inter-species interactions, supported by extensive ab initio simulations. This enables us to derive important ensemble properties from the spectral distribution resulting from those multi-species effects for arbitrary mixtures. We further propose a potential experimental implementation with a novel cryogenic target, delivering jets with variable mixtures of hydrogen and deuterium. Free from contaminants and without strong influence of hardly controllable processes such as ionization dynamics, this would allow a systematic realization of our predictions for the multi-species effect.Comment: 4 pages plus appendix, 11 figures, paper submitted to a journal of the American Physical Societ
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