2,106 research outputs found

    Mechanisms in Adaptive Feedback Control: Photoisomerization in a Liquid

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    The underlying mechanism for Adaptive Feedback Control in the experimental photoisomerization of NK88 in methanol is exposed theoretically. With given laboratory limitations on laser output, the complicated electric fields are shown to achieve their targets in qualitatively simple ways. Further, control over the cis population without laser limitations reveals an incoherent pump-dump scenario as the optimal isomerization strategy. In neither case are there substantial contributions from quantum multiple-path interference or from nuclear wavepacket coherence. Environmentally induced decoherence is shown to justify the use of a simplified theoretical model.Comment: 10 pages, 3 figures, to be published in Phys. Rev. Let

    Hyperthermophilic Alpha-Glucosidase Gene and its Use

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    Recombinant, thermostable alpha-glucosidases from archaeal micro-organisms and isolated DNA encoding for such alpha-glucosidases are provided. The isolated DNA is obtained by use of DNA or antibody probes prepared from the DNA encoding S. sulfataricus alpha-glucosidase. Also provided are methods for producing recombinant archaeal thermostable alpha-glucosidase and transformants incorporating thermostable alpha-glucosidase. Autoprocessing of plant tissue through the use of transgenic thermostable glycosyl hydrolases is described

    Válaszok és kérdések - a filozófiai gondolkodás történetiségéről

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    Cultivating Talents and Social Responsibility

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    Survival of the Fittest: Overcoming Oxidative Stress at the Extremes of Acid, Heat and Metal

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    The habitat of metal respiring acidothermophilic lithoautotrophs is perhaps the most oxidizing environment yet identified. Geothermal heat, sulfuric acid and transition metals contribute both individually and synergistically under aerobic conditions to create this niche. Sulfuric acid and metals originating from sulfidic ores catalyze oxidative reactions attacking microbial cell surfaces including lipids, proteins and glycosyl groups. Sulfuric acid ����� ��������� ������������ ������������ ������������� ��� ���� ���������� ��� ������ �������� carbon. Oxidative reactions leading to abstraction of electrons is further impacted by heat through an increase in the proportion of reactant molecules with sufficient energy to react. Collectively these factors and particularly those related to metals must be overcome by thermoacidophilic lithoautotrophs in order for them to survive and proliferate. The necessary mechanisms to achieve this goal are largely unknown however mechanistics insights have been gained through genomic studies. This review focuses on the specific role of metals in this extreme environment with an emphasis on resistance mechanisms in Archaea

    Techno-economic and environmental analysis of an Aquifer Thermal Energy Storage (ATES) in Germany

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    Abstract The objective of the present study is to analyse the economic and environmental performance of ATES for a new building complex of the municipal hospital in Karlsruhe, Germany. The studied ATES has a cooling capacity of 3.0 MW and a heating capacity of 1.8 MW. To meet the heating and cooling demand of the studied building, an overall pumping rate of 963 m3/h is required. A Monte Carlo Simulation provides a probability distribution of the capital costs of the ATES with a mean value of 1.3 ± (0.1) million €. The underground part of the ATES system requires about 60% of the capital costs and therefore forms the major cost factor. In addition, the ATES is compared with the presently installed supply technology of the hospital, which consists of compression chillers for cooling and district heating. Despite the 50% higher capital costs of the ATES system, an average payback time of about 3 years is achieved due to lower demand-related costs. The most efficient supply option is direct cooling by the ATES resulting in an electricity cost reduction of 80%. Compared to the reference system, the ATES achieves CO2 savings of about 600 tons per year, hence clearly demonstrating the potential economic and environmental benefits of ATES in Germany

    A Comment on the Topological Phase for Anti-Particles in a Lorentz-violating environment

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    Recently, a scheme to analyse topological phases in Quantum Mechanics by means of the non-relativistic limit of fermions non-minimally coupled to a Lorentz-breaking background has been proposed. In this letter, we show that the fixed background, responsible for the Lorentz-symmetry violation, may induce opposite Aharonov-Casher phases for a particle and its corresponding antiparticle. We then argue that such a difference may be used to investigate the asymmetry for particle/anti-particle as well as to propose bounds on the associated Lorentz-symmetry violating parameters.Comment: 4 pages - A published versio

    Identification of the ATPase Subunit of the Primary Maltose Transporter in the Hyperthermophilic Anaerobe \u3ci\u3eThermotoga maritima\u3c/i\u3e

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    Thermotoga maritima is a hyperthermophilic anaerobic bacterium that produces molecular hydrogen (H2) by fermentation. It catabolizes a broad range of carbohydrates through the action of diverse ABC transporters. However, in T. maritima and related species, highly similar genes with ambiguous annotation obscure a precise understanding of genome function. In T. maritima, three putative malK genes, all annotated as ATPase subunits, exhibited high identity to each other. To distinguish between these genes, malK disruption mutants were constructed by gene replacement, and the resulting mutant cell lines were characterized. Only a disruption of malK3 produced a defect in maltose catabolism. To verify that the mutant phenotype arose specifically from malK3 inactivation, the malK3 mutation was repaired by recombination, and maltose catabolism was restored. This study demonstrates the importance of a maltose ABC-type transporter and its relationship to sugar metabolism in T. maritima. IMPORTANCE: The application and further development of a genetic system was used here to investigate gene paralogs in the hyperthermophile Thermotoga maritima. The occurrence of three ABC transporter ATPase subunits all annotated as malK was evaluated using a combination of genetic and bioinformatic approaches. The results clarify the role of only one malK gene in maltose catabolism in a nonmodel organism noted for fermentative hydrogen production. Includes supplemental material
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