295 research outputs found

    A zonal computational procedure adapted to the optimization of two-dimensional thrust augmentor inlets

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    A viscous-inviscid interaction methodology based on a zonal description of the flowfield is developed as a mean of predicting the performance of two-dimensional thrust augmenting ejectors. An inviscid zone comprising the irrotational flow about the device is patched together with a viscous zone containing the turbulent mixing flow. The inviscid region is computed by a higher order panel method, while an integral method is used for the description of the viscous part. A non-linear, constrained optimization study is undertaken for the design of the inlet region. In this study, the viscous-inviscid analysis is complemented with a boundary layer calculation to account for flow separation from the walls of the inlet region. The thrust-based Reynolds number as well as the free stream velocity are shown to be important parameters in the design of a thrust augmentor inlet

    The utility of daily mood ratings in clinical trials of patients with bipolar II disorder

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    Objective: To demonstrate that there can be distinctive differences in information generated by standard interval measures as against using daily monitoring for evaluating progress in those with a bipolar disorder. Method: We undertook a 20-week study of individuals with a bipolar II disorder randomly assigned to receive either lamotrigine or lithium. Patients were rated on standard measures of depression and hypomania at monthly intervals, and they also completed a daily rating measure of their mood swings. We sought to demonstrate the potential for differing interpretations that emerge from these measurement strategies. Results: We graphed data for one subject who showed distinct improvement but demonstrated distinctly differing trajectories provided by monthly and daily data. In a second analysis, we considered sets of those who were judged as improving distinctly with lithium or lamotrigine to determine whether the drugs differed in speed of action, and again observed differing patterns between monthly and daily rating measures. Conclusions: A daily rating strategy appeared to provide additional and differing data compared to standard monthly measures. We therefore argue for the inclusion of daily mood ratings in clinical trials evaluating mood stabilisers and their use by clinicians in managing those with a bipolar II disorder

    Stability of central finite difference schemes for the Heston PDE

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    This paper deals with stability in the numerical solution of the prominent Heston partial differential equation from mathematical finance. We study the well-known central second-order finite difference discretization, which leads to large semi-discrete systems with non-normal matrices A. By employing the logarithmic spectral norm we prove practical, rigorous stability bounds. Our theoretical stability results are illustrated by ample numerical experiments

    A morphological, biological and molecular approach reveals four cryptic species of Trissolcus Ashmead (Hymenoptera, Scelionidae), egg parasitoids of Pentatomidae (Hemiptera)

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    Accurate identification of parasitoids is crucial for biological control of the invasive brown marmorated stink bug, Halyomrpha halys (Stål). A recent work by Talamas et al. (2017) revised the Palearctic fauna of Trissolcus Ashmead, egg-parasitoids of stink bugs, and treated numerous species as junior synonyms of T. semistriatus (Nees von Esenbeck). In the present paper, we provide a detailed taxonomic history and treatment of T. semistriatus and the species treated as its synonyms by Talamas et al. (2017) based on examination of primary types, molecular analyses and mating experiments. Trissolcus semistriatus, T. belenus (Walker), T. colemani (Crawford), and T. manteroi (Kieffer) are here recognized as valid and a key to species is provided. The identification tools provided here will facilitate the use of Trissolcus wasps as biological control agents and as the subject of ecological studies
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