3,790 research outputs found

    The general linear group as a complete invariant for C*-algebras

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    In 1955 Dye proved that two von Neumann factors not of type I_2n are isomorphic (via a linear or a conjugate linear *-isomorphism) if and only if their unitary groups are isomorphic as abstract groups. We consider an analogue for C*-algebras. We show that the topological general linear group is a classifying invariant for simple, unital AH-algebras of slow dimension growth and of real rank zero, and the abstract general linear group is a classifying invariant for unital Kirchberg algebras in the UCT class.Comment: 23 page

    Purely infinite partial crossed products

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    Let (A,G,\alpha) be a partial dynamical system. We show that there is a bijective correspondence between G-invariant ideals of A and ideals in the partial crossed product A xr G provided the action is exact and residually topologically free. Assuming, in addition, a technical condition---automatic when A is abelian---we show that A xr G is purely infinite if and only if the positive nonzero elements in A are properly infinite in A xr G. As an application we verify pure infiniteness of various partial crossed products, including realisations of the Cuntz algebras O_n, O_A, O_N, and O_Z as partial crossed products.Comment: 30 page

    Park Place at North Main

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    USAGE AND ACCEPTABIITY OF DATA NORMALIZATION IN BASEBALL PITCHING

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    To account for athletes of different sizes, kinetic values are commonly ‘normalized’ by dividing by mass and/or height. However, the creation of a ratio variable requires certain statistical assumptions to be met. The purpose of this study was to determine if elbow valgus torque predicted by pitching velocity is influenced by the normalization method using regression model comparison with normalized torque values. Both mass and mass*height normalization satisfied the correlation and zero intercept assumptions. Results did not agree between analysis methods that elbow valgus torque could be predicted with pitching velocity at the α = 0.05 level, indicating caution should be exercised before normalizing pitching kinetics data without confirming the assumptions for a ratio variable are met

    Unreinforced and TRM-reinforced masonry building subjected to pseudo-dynamic excitations: numerical and experimental insights

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    [EN] This paper contains a numerical study based on tests carried out at the Universitat Politècnica de València (Spain) on a U-shaped unreinforced and TRM-reinforced masonry building structure subjected to horizontal loads. The masonry was composed of clay bricks with 10 mm thick mortar joints arranged in an English bond manner. The prototype was tested by applying pseudo-dynamic displacement-driven cycles and varying cyclic amplitudes and frequencies in two different stages: (i) on the as-built structure and (ii) after the repair and the application of Textile Reinforced Mortar (TRM) material. A series of non-linear numerical simulations were performed adopting the ABAQUS/Explicit FE software. The FE calibration was carried out using the results obtained during ambient vibration tests. Simulations were then used to evaluate the effectiveness of the proposed TRM technique to increasing the strength of low-rise old masonry building structures.The authors would like to express their gratitude to the Spanish Ministry of Economy, Industry and Competitiveness for the funding provided (BIA 2014-59036-R-AR), and also to the Grupo Mapei and Grupo Puma for their invaluable assistance during the experimental tests.Giordano, E.; Bertolesi, E.; Clementi, F.; Buitrago, M.; Adam, JM.; Ivorra Chorro, S. (2021). Unreinforced and TRM-reinforced masonry building subjected to pseudo-dynamic excitations: numerical and experimental insights. Journal of Engineering Mechanics. 147(12):04021107-1-04021107-15. https://doi.org/10.1061/(ASCE)EM.1943-7889.0002017S04021107-104021107-151471

    THE RELATIONSHIP BETWEEN TRUNK ENERGY FLOW AND COLLEGIATE SOFTBALL HITTING PERFORMANCE

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    The purpose of this study was to determine the relationship between trunk energy flow and performance (exit velocity) during collegiate softball hitting. Nineteen collegiate softball athletes (age: 19.6 ± 1.0yrs) performed three maximal effort swings off a pitching machine. Kinematic data were collected using an electromagnetic tracking system. A segmental power analysis was performed to quantify peak rates of trunk energy flow (proximal inflow (IF) and distal outflow (OF) on front and back sides). Regression analyses determined exit velocity was best predicted by peak rate of distal trunk energy OF on the front side. On average, the model showed exit velocity increased by .9 mph for every 100 W increase in distal trunk energy OF on the front side while holding body mass constant
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