740 research outputs found

    URBAN SPRAWL AND OBESITY

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    In the U.S., urban sprawl and the rise in obesity rates have been two powerful trends during the latter half of the 20th century. Previous empirical work has found that obesity rates are influenced by labor market outcomes that are fundamentally shaped by the spatial pattern of developed land. We examine these potential linkages in an urban spatial model augmented to include time allocation and weight. Residents maximize utility defined over housing, weight, and food subject to a fixed time budget allocated to commuting, calorie expenditure, and work. We examine how weight is affected by commuting distance, food prices, and the rate of calorie expenditure; how a reduction in transportation costs affects weight throughout the city; and how initial weight affects location decisions. We identify, and explore the significance of, the conditions under which weight gain is associated with common features of sprawl.Food Consumption/Nutrition/Food Safety,

    A Suboptimality Approach to Distributed Linear Quadratic Optimal Control

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    This note is concerned with a suboptimal version of the distributed linear quadratic optimal control problem for multiagent systems. Given a multiagent system with identical agent dynamics and an associated global quadratic cost functional, our objective is to design distributed control laws that achieve consensus and whose cost is smaller than an a priori given upper bound, for all initial states of the network that are bounded in norm by a given radius. A centralized design method is provided to compute such suboptimal controllers, involving the solution of a single Riccati inequality of dimension equal to the dimension of the agent dynamics, and the smallest nonzero and the largest eigenvalue of the Laplacian matrix. Furthermore, we relax the requirement of exact knowledge of the smallest nonzero and largest eigenvalue of the Laplacian matrix by using only lower and upper bounds on these eigenvalues. Finally, a simulation example is provided to illustrate our design method

    Top-quark FCNC Productions at LHC in Topcolor-assisted Technicolor Model

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    We evaluate the top-quark FCNC productions induced by the topcolor assisted technicolor (TC2) model at the LHC. These productions proceed respectively through the parton-level processes g g -> t c_bar, c g->t, c g -> t g, c g -> t Z and c g -> t \gamma. We show the dependence of the production rates on the relevant TC2 parameters and compare the results with the predictions in the minimal supersymmetric model. We find that for each channel the TC2 model predicts a much larger production rate than the supersymmetric model. All these rare productions in the TC2 model can be enhanced above the 3-sigma sensitivity of the LHC. Since in the minimal supersymmetric model only c g -> t is slightly larger than the corresponding LHC sensitivity, the observation of these processes will favor the TC2 model over the supersymmetric model. In case of unobservation, the LHC can set meaningful constraints on the TC2 parameters.Comment: 5 pages, 4 fig
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