2,826 research outputs found

    Gaussian approximation for finitely extensible bead-spring chains with hydrodynamic interaction

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    The Gaussian Approximation, proposed originally by Ottinger [J. Chem. Phys., 90 (1) : 463-473, 1989] to account for the influence of fluctuations in hydrodynamic interactions in Rouse chains, is adapted here to derive a new mean-field approximation for the FENE spring force. This "FENE-PG" force law approximately accounts for spring-force fluctuations, which are neglected in the widely used FENE-P approximation. The Gaussian Approximation for hydrodynamic interactions is combined with the FENE-P and FENE-PG spring force approximations to obtain approximate models for finitely-extensible bead-spring chains with hydrodynamic interactions. The closed set of ODE's governing the evolution of the second-moments of the configurational probability distribution in the approximate models are used to generate predictions of rheological properties in steady and unsteady shear and uniaxial extensional flows, which are found to be in good agreement with the exact results obtained with Brownian dynamics simulations. In particular, predictions of coil-stretch hysteresis are in quantitative agreement with simulations' results. Additional simplifying diagonalization-of-normal-modes assumptions are found to lead to considerable savings in computation time, without significant loss in accuracy.Comment: 26 pages, 17 figures, 2 tables, 75 numbered equations, 1 appendix with 10 numbered equations Submitted to J. Chem. Phys. on 6 February 200

    Patching task-level robot controllers based on a local µ-calculus formula

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    We present a method for mending strategies for GR(1) specifications. Given the addition or removal of edges from the game graph describing a problem (essentially transition rules in a GR(1) specification), we apply a µ-calculus formula to a neighborhood of states to obtain a “local strategy” that navigates around the invalidated parts of an original synthesized strategy. Our method may thus avoid global resynthesis while recovering correctness with respect to the new specification. We illustrate the results both in simulation and on physical hardware for a planar robot surveillance task

    Myc-binding Protein Orthologue Interacts with AKAP240 In the Central Pair Apparatus of the \u3cem\u3eChlamydomonas\u3c/em\u3e Flagella

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    Background Flagella and cilia are fine thread-like organelles protruding from cells that harbour them. The typical ‘9 + 2’ cilia confer motility on these cells. Although the mechanistic details of motility remain elusive, the dynein-driven motility is regulated by various kinases and phosphatases. A-kinase anchoring proteins (AKAPs) are scaffolds that bind to a variety of such proteins. Usually, they are known to possess a dedicated domain that in vitro interacts with the regulatory subunits (RI and RII) present in the cAMP-dependent protein kinase (PKA) holoenzyme. These subunits conventionally harbour contiguous stretches of a.a. residues that reveal the presence of the Dimerization Docking (D/D) domain, Catalytic interface domain and cAMP-Binding domain. The Chlamydomonas reinhardtii flagella harbour two AKAPs; viz., the radial spoke AKAP97 or RSP3 and the central pair AKAP240. Both these were identified on the basis of their RII-binding property. Interestingly, AKAP97 binds in vivo to two RII-like proteins (RSP7 and RSP11) that contain only the D/D domain. Results We found a Chlamydomonas Flagellar Associated Protein (FAP174) orthologous to MYCBP-1, a protein that binds to organellar AKAPs and Myc onco-protein. An in silico analysis shows that the N-terminus of FAP174 is similar to those RII domain-containing proteins that have binding affinities to AKAPs. Binding of FAP174 was tested with the AKAP97/RSP3 using in vitro pull down assays; however, this binding was rather poor with AKAP97/RSP3. Antibodies were generated against FAP174 and the cellular localization was studied using Western blotting and immunoflourescence in wild type and various flagella mutants. We show that FAP174 localises to the central pair of the axoneme. Using overlay assays we show that FAP174 binds AKAP240 previously identified in the C2 portion of the central pair apparatus. Conclusion It appears that the flagella of Chlamydomonas reinhardtii contain proteins that bind to AKAPs and except for the D/D domain, lack the conventional a.a. stretches of PKA regulatory subunits (RSP7 and RSP11). We add FAP174 to this growing list

    Invitro Antimicrobial Activity and Phytochemical Analysis of Ficus religiosa L. and Ficus bengalensis L. against Diarrhoeal Enterotoxigenic E. coli

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    The barks of Ficus religiosa L. and Ficus bengalensis L., which belongs to family Moraceae, were investigated for invitro antibacterial activity and phytochemical analysis. The various solvents extract like aqueous, methanol, chloroform, petroleum ether and hexane were screened for antibacterial activity against Enterotoxigenic E. coli isolated from diarrhoeal patients. The preliminary phytochemical analysis of the methanol extracts of both the plants showed the presence of carbohydrates, flavonoids, aminoacids, steroids, saponins and tannins. The extracts were subjected for antibacterial activity against Enterotoxignic E.coli (ETEC) at 200mg/ml concentration by disc diffusion method. The results of antibacterial activity revealed that methanol extracts of both the plants barks exhibits good activity compared to chloroform and aqueous extracts. Petroleum ether and hexane extracts did not show any activity. The antibacterial activities of extracts were compared with standard antibiotics

    Acoustical-Mode-Driven Electron-Phonon Coupling in Transition-Metal Diborides

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    We show that the electron-phonon coupling in the transition-metal diborides NbB2 and TaB2 is dominated by the longitudinal acoustical (LA) mode, in contrast to the optical E_{2g} mode dominated coupling in MgB2. Our ab initio results, described in terms of phonon dispersion, linewidth, and partial electron-phonon coupling along Gamma to A, also show that (i) NbB2 and TaB2 have a relatively weak electron-phonon coupling, (ii) the E_{2g} linewidth is an order of magnitude larger in MgB2 than in NbB2 or TaB2, (iii) the E_{2g} frequency in NbB2 and TaB2 is considerably higher than in MgB2, and (iv) the LA frequency at A for TaB2 is almost half of that of MgB2 or NbB2.Comment: 4 pages, 4 figures, and 1 tabl

    Проектирование электрической части ТЭЦ установленной мощностью 127 МВт

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    Объектом исследования является электрическая часть теплоэлектроцентрали. Целью работы является проектирование электрической части теплоэлектроцентрали, выбор основное силовое оборудование, выполнения расчет режима работы трансформатора, исследование вставки постоянного тока. Актуальность проектирования теплоэлектроцентрали заключается в том, что их мощность обычно такова, что может обеспечить электроэнергией город. Так же имеется возможно обеспечить город теплоснабжением.The object of the study is the electrical part of the co-generation plant. The aim of the work is the design of the electrical part of the co-generation plant, the selection of the main power equipment, the calculation of the operating mode of the transformer, the study of the high-voltage direct current link. The actuality of designing a co-generation plant is that their power is usually such that it can provide electricity to the city. It is also possible to provide the city with heat

    Filtering data streams for entity-based continuous queries

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    The idea of allowing query users to relax their correctness requirements in order to improve performance of a data stream management system (e.g., location-based services and sensor networks) has been recently studied. By exploiting the maximum error (or tolerance) allowed in query answers, algorithms for reducing the use of system resources have been developed. In most of these works, however, query tolerance is expressed as a numerical value, which may be difficult to specify. We observe that in many situations, users may not be concerned with the actual value of an answer, but rather which object satisfies a query (e.g., "who is my nearest neighbor?). In particular, an entity-based query returns only the names of objects that satisfy the query. For these queries, it is possible to specify a tolerance that is "nonvalue-based. In this paper, we study fraction-based tolerance, a type of nonvalue-based tolerance, where a user specifies the maximum fractions of a query answer that can be false positives and false negatives. We develop fraction-based tolerance for two major classes of entity-based queries: 1) nonrank-based query (e.g., range queries) and 2) rank-based query (e.g., k-nearest-neighbor queries). These definitions provide users with an alternative to specify the maximum tolerance allowed in their answers. We further investigate how these definitions can be exploited in a distributed stream environment. We design adaptive filter algorithms that allow updates be dropped conditionally at the data stream sources without affecting the overall query correctness. Extensive experimental results show that our protocols reduce the use of network and energy resources significantly. © 2006 IEEE.published_or_final_versio

    Composite CDMA - A statistical mechanics analysis

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    Code Division Multiple Access (CDMA) in which the spreading code assignment to users contains a random element has recently become a cornerstone of CDMA research. The random element in the construction is particular attractive as it provides robustness and flexibility in utilising multi-access channels, whilst not making significant sacrifices in terms of transmission power. Random codes are generated from some ensemble, here we consider the possibility of combining two standard paradigms, sparsely and densely spread codes, in a single composite code ensemble. The composite code analysis includes a replica symmetric calculation of performance in the large system limit, and investigation of finite systems through a composite belief propagation algorithm. A variety of codes are examined with a focus on the high multi-access interference regime. In both the large size limit and finite systems we demonstrate scenarios in which the composite code has typical performance exceeding sparse and dense codes at equivalent signal to noise ratio.Comment: 23 pages, 11 figures, Sigma Phi 2008 conference submission - submitted to J.Stat.Mec

    Antimicrobial Activity and Phytochemical Analysis of Coriander sativum Against Infectious Diarrhea

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    The preliminary phytochemical study and invitro antimicrobial activity of Coriander sativum (Apiaceae) was investigated against some pathogens isolated from patients with infectious diarrhea. The various solvents extract like aqueous, methanol, chloroform, petroleum ether and hexane were screened for antimicrobial activity against Enterotoxigenic E.coli, Enteropathogenic E.coli,, Salmonella typhimurium, Salmonella entertidis, Shigella dysentriae, Shigella flexineri, Candida albicans, Candida tropicalis and Candida krusei isolated from diarrhoeal patients. The preliminary phytochemical analysis of the methanol extracts of the plant showed the presence of carbohydrates, flavonoids, aminoacids, steroids, sterols, saponins and tannins. The extracts were subjected for antimicrobial activity against at 200mg/ml concentration by disc diffusion method. The results of antimicrobial activity revealed that methanol extract of the plant exhibit good activity compared to chloroform and aqueous extracts to E.coli, Salmonella sp and Shigella sp. Petroleum ether and hexane extracts did not show any activity. None of extracts exhibits antifungal activity. The antimicrobial activities of extracts were compared with standard antibiotics
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