6,204 research outputs found

    Data Driven Surrogate Based Optimization in the Problem Solving Environment WBCSim

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    Large scale, multidisciplinary, engineering designs are always difficult due to the complexity and dimensionality of these problems. Direct coupling between the analysis codes and the optimization routines can be prohibitively time consuming due to the complexity of the underlying simulation codes. One way of tackling this problem is by constructing computationally cheap(er) approximations of the expensive simulations, that mimic the behavior of the simulation model as closely as possible. This paper presents a data driven, surrogate based optimization algorithm that uses a trust region based sequential approximate optimization (SAO) framework and a statistical sampling approach based on design of experiment (DOE) arrays. The algorithm is implemented using techniques from two packages—SURFPACK and SHEPPACK that provide a collection of approximation algorithms to build the surrogates and three different DOE techniques—full factorial (FF), Latin hypercube sampling (LHS), and central composite design (CCD)—are used to train the surrogates. The results are compared with the optimization results obtained by directly coupling an optimizer with the simulation code. The biggest concern in using the SAO framework based on statistical sampling is the generation of the required database. As the number of design variables grows, the computational cost of generating the required database grows rapidly. A data driven approach is proposed to tackle this situation, where the trick is to run the expensive simulation if and only if a nearby data point does not exist in the cumulatively growing database. Over time the database matures and is enriched as more and more optimizations are performed. Results show that the proposed methodology dramatically reduces the total number of calls to the expensive simulation runs during the optimization process

    Electroweak Model Independent Tests for SU(3) Symmetry in Hadronic B Decays

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    We study effects of new physics beyond the Standard Model on SU(3) symmetry in charmless hadronic two body B decays. It is found that several equalities for some of the decay amplitudes, such as A(Bd(Bu)π+π,π+K(πKˉ0))=A(BsK+π,KK+(K0Kˉ0))A(B_d (B_u) \to \pi^+\pi^-,\pi^+ K^- (\pi^- \bar K^0)) =A(B_s \to K^+ \pi^-, K^- K^+ (K^0 \bar K^0)), A(Bdπ+ρ,πρ+,Kρ+,π+K)=A(BsK+ρ,πK+,KK+,K+K)A(B_d \to \pi^+\rho^-, \pi^- \rho^+, K^-\rho^+, \pi^+ K^{*-}) = A(B_s \to K^+ \rho^-, \pi^- K^{*+}, K^- K^{*+}, K^+ K^{*-}), A(Bd(Bu)ρ+ρ,ρ+K(ρKˉ0))=A(BsK+ρ,KK+(K0Kˉ0))A(B_d (B_u) \to \rho^+\rho^-, \rho^+ K^{*-}(\rho^- \bar K^{*0})) =A(B_s \to K^{*+} \rho^-, K^{*-} K^{*+} (K^{*0} \bar K^{*0})), predicted by SU(3) symmetry in the SM are not affected by new physics. These relations provide important electroweak model independent tests for SU(3) symmetry in B decays.Comment: 4 pages, revte

    Histopathological changes in the gill architecture of Labeo rohita from the pond adjacent to thermal power station, Koradi, Nagpur, India

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    The hazardous effect of water pollution on the histopathology of selected organs of the freshwater fish Labeo rohita was studied with respect to thermal power plant effluent. The purpose of this research paper is to study whether the thermal plume can affect fish assemblages in the waters around the outlet area of the thermal power plant located at Koradi near Nagpur city. Both experimental and control fishes were monitored for a year from March 2010 to Feb. 2011. Histopathology serve as a tool to assess the extent of damage caused to the organism.Gill tissue showed fusion of primary lamellae, congestion of blood vessels and hyperplasia of bronchial plates. The histopathological changes in the gill tissue include epithelial hyperplasia, curling of secondary lamellae and changes in chloride cells. Besides these changes pyknotic nuclei, vacuolization, degradation of epithelial and pillar cells, were noticed, which point out towards deleterious effect of thermal power plant effluent on the freshwater fish L. rohita

    Diffuse large B cell lymphoma of submandibular gland in a seropositive case – a rare presentation

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    Lymphomas account for 2%-5% of salivary gland neoplasms. The parotid gland is the most commonly involved, constituting 70% of the cases, followed by submandibular gland (25%), sublingual and minor salivary glands (<10%). In present study a 56 years old seropositive male presented with a submandibular gland swelling of 2 months duration; along with multiple cervical lymphadenopathy. Grossly a single, well encapsulated, grayish-white tissue measuring 3x2.5x2 cms was received. It was solid, grayish-white on cut section. Histology revealed features of diffuse large B cell lymphoma with myoepithelial sialadenitis. Immunohistochemistry showed positivity for LCA & CD20, thus confirming the histopathological diagnosis. Primary malignant lymphoma of salivary glands is uncommon. Inspite of malignant lymphoma being the second most common AIDS-associated neoplasm, it’s occurrence in submandibular gland is extremely rare

    Pharmacological Blockade of the Calcium Plateau Provides Neuroprotection Following Organophosphate Paraoxon Induced Status Epilepticus in Rats

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    Organophosphate (OP) compounds which include nerve agents and pesticides are considered chemical threat agents. Currently approved antidotes are crucial in limiting OP mediated acute mortality. However, survivors of lethal OP exposure exhibit delayed neuronal injury and chronic behavioral morbidities. In this study, we investigated neuroprotective capabilities of dantrolene and carisbamate in a rat survival model of paraoxon (POX) induced status epilepticus (SE). Significant elevations in hippocampal calcium levels were observed 48-h post POX SE survival, and treatment with dantrolene (10 mg/kg, i.m.) and carisbamate (90 mg/kg, i.m.) lowered these protracted calcium elevations. POX SE induced delayed neuronal injury as characterized by Fluoro Jade C labeling was observed in critical brain areas including the dentate gyrus, parietal cortex, amygdala, and thalamus. Dantrolene and carisbamate treatment provided significant neuroprotection against delayed neuronal damage in these brain regions when administered one-hour after POX-SE. These results indicate that dantrolene or carisbamate could be effective adjuvant therapies to the existing countermeasures to reduce neuronal injury and behavioral morbidities post OP SE survival

    Restricted Wiedemann-Franz law and vanishing thermoelectric power in one-dimensional conductors

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    In one-dimensional (1D) conductors with linear E-k dispersion (Dirac systems) intrabranch thermalization is favored by elastic electron-electron interaction in contrast to electron systems with a nonlinear (parabolic) dispersion. We show that under external electric fields or thermal gradients the carrier populations of different branches, treated as Fermi gases, have different temperatures as a consequence of self-consistent carrier-heat transport. Specifically, in the presence of elastic phonon scattering, the Wiedemann-Franz law is restricted to each branch with its specific temperature and is characterized by twice the Lorenz number. In addition thermoelectric power vanishes due to electron-hole symmetry, which is validated by experiment.Comment: 10 pages, 2 figure
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