412,259 research outputs found

    Kinks in Time and their Relation to Confinement

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    The time dependent formation of an electric flux tube (fundamental string) is reviewed. The main tool used for analysis is the Spacelike brane, which is a kink in time of the rolling tachyon. Both the S-brane and rolling tachyon are attempts to extend the D-brane concept to time dependent backgrounds. While S-branes are similar to Euclidean counterparts of the more familiar timelike D-branes, S-branes can smoothly change their worldvolume signature from spacelike to timelike which we interpret as the formation of a topological defect.Comment: 5 pages, 3 figures. To appear in the Proceedings of Confinement 200

    Analysis of the vertex DDρD^*D^* \rho with the light-cone QCD sum rules

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    In this article, we analyze the vertex DDρD^*D^*\rho with the light-cone QCD sum rules. The strong coupling constant gDDρg_{D^*D^*\rho} is an important parameter in evaluating the charmonium absorption cross sections in searching for the quark-gluon plasmas. Our numerical value for the gDDρg_{D^*D^*\rho} is consistent with the prediction of the effective SU(4) symmetry and vector meson dominance theory.Comment: 6 pages, 1 figure, revised versio

    Robust Multi-Criteria Optimal Fuzzy Control of Discrete-Time Nonlinear Systems

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    This paper presents a novel fuzzy control design of discrete-time nonlinear systems with multiple performance criteria. The purpose behind this work is to improve the traditional fuzzy controller performance to satisfy several performance criteria simultaneously to secure quadratic optimality with an inherent stability property together with a dissipativity type of disturbance reduction. The Takagi–Sugeno-type fuzzy model is used in our control system design. By solving a linear matrix inequality at each time step, the optimal control solution can be found to satisfy mixed performance criteria. The effectiveness of the proposed technique is demonstrated by simulation of the control of the inverted pendulum system on a cart

    Congener Host Selection by the Pre-Dispersal Seed Predator, \u3ci\u3eApion Rostrum\u3c/i\u3e (Coleoptera: Apionidae)

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    Apion rostrum Say (Coleoptera: Apionidae) is the major seed predator of the wild indigo congeners, Baptisia alba and B. bracteata in the Russell Kirt Tallgrass Prairie, a reconstructed prairie located at College of DuPage, Illinois. This study, conducted during 2006, investigated factors attracting A. rostrum to each congener. The two Baptisia differ in developmental period, stature, and patterns of dispersion. B. bracteata flowers and initiates pods usually along a single raceme during late spring, and is a shorter plant that grows in clusters. In contrast, B. alba flowers and initiates pods beginning a month after B. bracteata, produces a tall central raceme with often several satellite racemes, and does not grow in dense clusters. Mating and ovipositing A. rostrum were observed on B. bracteata during the first half of June, and with greater abundance on B. alba from early June through mid July. Results of stepwise multiple regression showed a positive relationship of weevil counts per plant to raceme counts per cluster for B. bracteata and to inflated pod counts per plant for B. alba. The developmental synchrony between A. rostrum and pods of B. alba is evidence of a closer evolutionary relationship than the seed predator has with B. bracteata. This can explain the greater number of reproductive weevils seen on B. alba as well as the higher levels of pod infestations
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