2,316 research outputs found

    Effective Capacity and Randomness of Closed Sets

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    We investigate the connection between measure and capacity for the space of nonempty closed subsets of {0,1}*. For any computable measure, a computable capacity T may be defined by letting T(Q) be the measure of the family of closed sets which have nonempty intersection with Q. We prove an effective version of Choquet's capacity theorem by showing that every computable capacity may be obtained from a computable measure in this way. We establish conditions that characterize when the capacity of a random closed set equals zero or is >0. We construct for certain measures an effectively closed set with positive capacity and with Lebesgue measure zero

    On Revenue Maximization with Sharp Multi-Unit Demands

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    We consider markets consisting of a set of indivisible items, and buyers that have {\em sharp} multi-unit demand. This means that each buyer ii wants a specific number did_i of items; a bundle of size less than did_i has no value, while a bundle of size greater than did_i is worth no more than the most valued did_i items (valuations being additive). We consider the objective of setting prices and allocations in order to maximize the total revenue of the market maker. The pricing problem with sharp multi-unit demand buyers has a number of properties that the unit-demand model does not possess, and is an important question in algorithmic pricing. We consider the problem of computing a revenue maximizing solution for two solution concepts: competitive equilibrium and envy-free pricing. For unrestricted valuations, these problems are NP-complete; we focus on a realistic special case of "correlated values" where each buyer ii has a valuation v_i\qual_j for item jj, where viv_i and \qual_j are positive quantities associated with buyer ii and item jj respectively. We present a polynomial time algorithm to solve the revenue-maximizing competitive equilibrium problem. For envy-free pricing, if the demand of each buyer is bounded by a constant, a revenue maximizing solution can be found efficiently; the general demand case is shown to be NP-hard.Comment: page2

    Perspective-aware texture analysis and synthesis

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    The original publication is available at www.springerlink.comInternational audienceThis paper presents a novel texture synthesis scheme for anisotropic 2D textures based on perspective feature analysis and energy optimization. Given an example texture, the synthesis process starts with analyzing the texel (TEXture ELement) scale variations to obtain the perspective map (scale map). Feature mask and simple user-assisted scale extraction operations including slant and tilt angles assignment and scale value editing are applied. The scale map represents the global variations of the texel scales in the sample texture. Then, we extend 2D texture optimization techniques to synthesize these kinds of perspectively featured textures. The non-parametric texture optimization approach is integrated with histogram matching, which forces the global statics of the texel scale variations of the synthesized texture to match those of the example. We also demonstrate that our method is well-suited for image completion of a perspectively featured texture region in a digital photo

    Robust tile-based texture synthesis using artificial immune system

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    The original publication is avalaible at www.springerlink.comInternational audienceOne significant problem in tile-based texture synthesis is the presence of conspicuous seams in the tiles. The reason is that sample patches employed as primary patterns of the tile set may not be well stitched if carelessly picked. In this paper, we introduce a robust approach that can stably generate an ω-tile set of high quality and pattern diversity. First, an extendable rule is introduced to increase the number of sample patches to vary the patterns in an ω-tile set. Second, in contrast to other concurrent techniques that randomly choose sample patches for tile construction, ours uses artificial immune system (AIS) to select the feasible patches from the input example. This operation ensures the quality of the whole tile set. Experimental results verify the high quality and efficiency of the proposed algorithm

    2-Hydr­oxy-Nâ€Č-[(1E,2E)-3-phenyl­prop-2-enyl­idene]benzohydrazide

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    In mol­ecule of the title compound, C16H14N2O2, the two aromatic rings form a dihedral angle of 6.93 (3)° and an intramolecular N—H⋯O hydrogen bond occurs. In the crystal structure, inter­molecular O—H⋯O hydrogen bonds link the mol­ecules into zigzag chains running in the [10] direction

    ECONOMIC REPLACEMENT OF A HETEROGENEOUS HERD

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    A model was developed and used to determine the optimal slaughter weights of pigs with heterogeneous growth raised in a 1,000 head barn and marketed in truckload groups. Explicitly recognizing the heterogeneity of pig weights and marketing the herd over time in truckload batches can substantially increase profit.Marketing,

    Parapneumonic empyema diagnosed by chest radiograph and computed tomography

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    Pleural effusion is commonly seen associated with pneumonia. When this progresses to empyema, directed therapy is frequently required. Chest radiographic and computed tomography findings can help distinguish empyema from a transudative pleural effusion

    Spin alignment of stars in old open clusters

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    Stellar clusters form by gravitational collapse of turbulent molecular clouds, with up to several thousand stars per cluster. They are thought to be the birthplace of most stars and therefore play an important role in our understanding of star formation, a fundamental problem in astrophysics. The initial conditions of the molecular cloud establish its dynamical history until the stellar cluster is born. However, the evolution of the cloud's angular momentum during cluster formation is not well understood. Current observations have suggested that turbulence scrambles the angular momentum of the cluster-forming cloud, preventing spin alignment amongst stars within a cluster. Here we use asteroseismology to measure the inclination angles of spin axes in 48 stars from the two old open clusters NGC~6791 and NGC~6819. The stars within each cluster show strong alignment. Three-dimensional hydrodynamical simulations of proto-cluster formation show that at least 50 % of the initial proto-cluster kinetic energy has to be rotational in order to obtain strong stellar-spin alignment within a cluster. Our result indicates that the global angular momentum of the cluster-forming clouds was efficiently transferred to each star and that its imprint has survived after several gigayears since the clusters formed.Comment: 14 pages, 3 figures, 1 table. Published in Nature Astronom

    A comparison of adaptive predictors in sub-band coding

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    Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1987.Bibliography: leaves 82-85.by Paul Ning.M.S
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