900 research outputs found

    Generation of Longitudinal Flux Tube Waves in Theoretical Main-Sequence Stars: Effects of Model Parameters

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    Context. Continued investigation of the linkage between magneto-acoustic energy generation in stellar convective zones and the energy dissipation and radiative emission in outer stellar atmospheres in stars of different activity levels. Aims. We compute the wave energy fluxes carried by longitudinal tube waves along vertically oriented thin magnetic fluxes tubes embedded in the atmospheres of theoretical main-sequence stars based on stellar parameters deduced by R. L. Kurucz and D. F. Gray. Additionally, we present a fitting formula for the wave energy flux based on the governing stellar and magnetic parameters. Methods. A modified theory of turbulence generation based on the mixing-length concept is combined with the magneto-hydrodynamic equations to numerically account for the wave energies generated at the base of magnetic flux tubes. Results. The results indicate a stiff dependence of the generated wave energy on the stellar and magnetic parameters in principal agreement with previous studies. The wave energy flux F_LTW decreases by about a factor of 1.7 between G0V and K0V stars, but drops by almost two orders of magnitude between K0V and M0V stars. In addition, the values for F_LTW are significantly higher for lower in-tube magnetic field strengths. Both results are consistent with the findings from previous studies. Conclusions. Our study will add to the description of magnetic energy generation in late-type main-sequence stars. Our results will be helpful for calculating theoretical atmospheric models for stars of different levels of magnetic activity.Comment: 9 pages, 5 figures, 6 tables; submitted to Astronomy & Astrophysic

    Authentic Dasein and the anxious uncanny

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    The philosophical reader cannot help but notice that some of the major assertions of Immanuel Kant and Martin Heidegger are thematically intertwined. Perhaps even more clearly, the viewer who approaches the work of Edvard Munch with a philosophical frame of mind will discover how the thoughts of Kant and Heidegger often illuminate key aspects of his paintings. Authentic Dasein and the Anxious Uncanny strives to analyze the main works of Edvard Munch, the father of Expressionism. This thesis uses Heidegger\u27s concepts of anxiety and being-towards-death, as well as Kant\u27s notion of the Sublime as laced with anxiety, to re-examine nineteen of the artist\u27s masterpieces. The first chapter explores the relationship between Kant and Munch, while the second focuses on artist\u27s works through the philosophy of Heidegger. The third and concluding chapter brings together Kant and Heidegger through a series of paintings to demonstrate how Munch\u27s achievement can be interpreted philosophically

    ブドウ‘マスカット・オブ・アレキサンドリア’に対する潅水制限が樹体の水分,葉温,果実温,果実の全フェノール含量,果皮色に及ぼす影響

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     Effects of different deficit irrigation strategies on vine water status, canopy and cluster temperatures, fruit total phenolics, and the color of white table grapes (Vitis vinifera L., cv. Muscat of Alexandria) were compared to a well-irrigated control in 2004 from veraison to harvest at the Okayama University Experimental Vineyard, Japan. The treatments included: (1) well-irrigated control: re-irrigation when the soil moisture tension reached 15 kPa; (2) regulated deficit irrigation (RDI): re-irrigation 4 to 7 days after reaching a soil moisture tension of 15 kPa; (3) fixed partial root-zone wetting (FPRW): one part of the root system was re-irrigated when the soil moisture tension reached 15 kPa; and (4) alternate partial root-zone wetting (APRW): one part of the root system was re-irrigated when the soil moisture tension reached 15 kPa, and every week the irrigated part was switched. As the stress developed in RDI vines, leaf water potential and transpiration rate decreased and canopy and cluster temperatures increased as compared with the control. In contrast, both FPRW and APRW vines had similar leaf water potential and canopy and cluster temperatures, but less leaf transpiration rate as compared with the control. At harvest, fruits from all treatments had higher skin total phenolics and CIELAB a* values than the control. RDI fruit had higher total soluble solids (TSS), a similar acidity, and smaller size compared with the control. FPRW and APRW fruits had slightly higher TSS, lower acidity, and a similar size compared with the control.ベレゾーン期から収穫期までの潅水制限処理が‘マスカット・オブ・アレキサンドリア’ブドウ(Vitis vinifera L。)の水分条件,葉温,果実温,果実の全フェノール,果皮色に及ぼす影響を,十分に潅水した樹と比較した.実験は2004年に岡山大学農学部内の実験圃場で行った.処理区は,1) 土壌水分張力が15kPa に達したときに潅水する対照区,2) 土壌水分張力が15kPa に達してから4~7日後に潅水する制限潅水区,3) 土壌水分張力が15kPa に達したときに根域の半分に潅水する片側潅水区,4) 片側潅水する根域部分を1週間ごとに変更する交互潅水区とした.制限潅水区では水分ストレスが強まるにつれて葉の水ポテンシャルと蒸散速度が対照区よりも低下し,果実温が高くなった.しかし,片側潅水区と交互潅水区では,葉の水ポテンシャルと葉温,果実温は対照区と同程度で,蒸散速度が低下した.収穫期の果皮の全フェノールと CIELAB a* 値は,潅水を制限した各区では標準区より高かった.制限潅水区の果実は,標準区より糖度が高く,酸度は低く,果粒は小さかった.片側潅水区,交互潅水区では糖度がやや高く,酸度は低く,果粒の大きさは同程度であった

    ORLease: Optimistically Replicated Lease Using Lease Version Vector For Higher Replica Consistency in Optimistic Replication Systems

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    There is a tradeoff between the availability and consistency properties of any distributed replication system. Optimistic replication favors high availability over strong consistency so that the replication system can support disconnected replicas as well as high network latency between replicas. Optimistic replication improves the availability of these systems by allowing data updates to be committed at their originating replicas first before they are asynchronously replicated out and committed later at the rest of the replicas. This leads the whole system to suffer from a relaxed data consistency. This is due to the lack of any locking mechanism to synchronize access to the replicated data resources in order to mutually exclude one another. When consistency is relaxed, there is a potential of reading from stale data as well as introducing data conflicts due to the concurrent data updates that might have been introduced at different replicas. These issues could be ameliorated if the optimistic replication system is aggressively propagating the data updates at times of good network connectivity between replicas. However, aggressive propagation for data updates does not scale well in write intensive environments and leads to communication overhead in order to keep all replicas in sync. In pursuance of a solution to mitigate the relaxed consistency drawback, a new technique has been developed that improves the consistency of optimistic replication systems without sacrificing its availability and with minimal communication overhead. This new methodology is based on applying the concurrency control technique of leasing in an optimistic way. The optimistic lease technique is built on top of a replication framework that prioritizes metadata replication over data replication. The framework treats the lease requests as replication metadata updates and replicates them aggressively in order to optimistically acquire leases on replicated data resources. The technique is demonstrating a best effort semi-locking semantics that improves the overall system consistency while avoiding any locking issues that could arise in optimistic replication systems
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