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Chaoping Xing - One of the best experts on this subject based on the ideXlab platform.

  • Torsion Limits and Riemann-Roch Systems for Function Fields and Applications
    IEEE Transactions on Information Theory, 2014
    Co-Authors: Ignacio Cascudo, Ronald Cramer, Chaoping Xing
    Abstract:

    The Ihara limit (or constant) A(q) has been a central problem of study in the asymptotic theory of Global Function fields (or equivalently, algebraic curves over finite fields). It addresses Global Function fields with many rational points and, so far, most applications of this theory do not require additional properties. Motivated by recent applications, we require Global Function fields with the additional property that their zero class divisor groups contain at most a small number of d -torsion points. We capture this with the notion of torsion limit, a new asymptotic quantity for Global Function fields. It seems that it is even harder to determine values of this new quantity than the Ihara constant. Nevertheless, some nontrivial upper bounds are derived. Apart from this new asymptotic quantity and bounds on it, we also introduce Riemann-Roch systems of equations. It turns out that this type of equation system plays an important role in the study of several other problems in each of these areas: arithmetic secret sharing, symmetric bilinear complexity of multiplication in finite fields, frameproof codes, and the theory of error correcting codes. Finally, we show how our new asymptotic quantity, our bounds on it and Riemann-Roch systems can be used to improve results in these areas.

  • Construction of Global Function fields from linear codes and vice versa
    Transactions of the American Mathematical Society, 2008
    Co-Authors: Chaoping Xing
    Abstract:

    We introduce a new connection between linear codes and Global Function fields, which in turn allows us to construct new Global Function fields with improved lower bounds on the number of rational places. The genus and number of rational places of subfields of certain families of cyclotomic Function fields are given as well.

  • New Linear Codes and Algebraic Function Fields Over Finite Fields
    IEEE Transactions on Information Theory, 2007
    Co-Authors: Chaoping Xing
    Abstract:

    In this correspondence, we present 129 new linear codes over F8 and F9 based on the construction by Xing and Niederreiter using algebraic Function fields and places of small degrees. In addition, we construct some Global Function fields in which the number of rational places improves the lower bounds given by van der Geer and van der Vlugt.

  • A Counterexample to Perret's Conjecture on Infinite Class Field Towers for Global Function Fields
    Finite Fields and Their Applications, 1999
    Co-Authors: Harald Niederreiter, Chaoping Xing
    Abstract:

    We show by a counterexample that Perret's conjecture on infinite class field towers for Global Function fields is wrong, and so Perret's method of infinite ramified class field towers in the asymptotic theory of Global Function fields with many rational places breaks down.

  • A general method of constructing Global Function fields with many rational places
    Lecture Notes in Computer Science, 1998
    Co-Authors: Harald Niederreiter, Chaoping Xing
    Abstract:

    We present a general method of constructing Global Function fields with many rational places based on Drinfeld modules of rank 1 and narrow ray class fields. This method leads to many improvements on previous constructions. We tabulate improvements for constant fields of order q=4,8,9,16, and 27.

Mustafa Kilic - One of the best experts on this subject based on the ideXlab platform.

L. Axel - One of the best experts on this subject based on the ideXlab platform.

  • Right ventricular wall mechanics in normals and patients with pulmonary hypertension using magnetic resonance tissue tagging
    Computers in Cardiology 1995, 1995
    Co-Authors: Z.a. Fayad, V.a. Ferrari, D.l. Kraitchman, A.a. Young, D.c. Bloomgarden, L. Axel
    Abstract:

    Right ventricular hypertrophy (RVH) and RV dysFunction are difficult to evaluate due to the complex shape of the RV and prognostic limitations of conventional Global Function parameters. We used MRI with magnetization tagging to measure 2-D systolic motion and deformation of the right ventricular free wall (RVFW) and septum (SEPT) in 5 patients with RVH secondary to pulmonary hypertension, and 12 normal volunteers (NL). Regional displacement (D) and 2-D principal strains in the short-axis plane were averaged at basal, midventricular and apical levels. SEPT D was severely decreased at all levels in RVH vs. NL (P

  • An integrated program for 2-D and 3-D analysis of heart wall motion from magnetic resonance imaging
    Computers in Cardiology 1995, 1995
    Co-Authors: L. Axel, Z.a. Fayad, D.l. Kraitchman, D.c. Bloomgarden, C.-n. Chang, A.a. Young
    Abstract:

    Magnetic resonance imaging (MRI) with magnetization tagging provides a non invasive tomographic imaging method for the evaluation of cardiac Function. We have developed an integrated set of programs for the analysis and display of heart wall motion from cardiac MRI. Cardiac wall contours and tag positions can be extracted manually or semiautomatically from the images. The contours can be stacked to calculate Global Function variables, or the relative motion of the tags in the images can be used to calculate the regional 2-D strain. Tag data from orthogonal sets of images can be combined to calculate regional 3-D strain. Display options include static or dynamic displays of scalar and vector or tensor quantities. This integrated program provides a useful means to extract and display cardiac Function data from tagged MRI.

Nese Dursunoglu - One of the best experts on this subject based on the ideXlab platform.

A.a. Young - One of the best experts on this subject based on the ideXlab platform.

  • Right ventricular wall mechanics in normals and patients with pulmonary hypertension using magnetic resonance tissue tagging
    Computers in Cardiology 1995, 1995
    Co-Authors: Z.a. Fayad, V.a. Ferrari, D.l. Kraitchman, A.a. Young, D.c. Bloomgarden, L. Axel
    Abstract:

    Right ventricular hypertrophy (RVH) and RV dysFunction are difficult to evaluate due to the complex shape of the RV and prognostic limitations of conventional Global Function parameters. We used MRI with magnetization tagging to measure 2-D systolic motion and deformation of the right ventricular free wall (RVFW) and septum (SEPT) in 5 patients with RVH secondary to pulmonary hypertension, and 12 normal volunteers (NL). Regional displacement (D) and 2-D principal strains in the short-axis plane were averaged at basal, midventricular and apical levels. SEPT D was severely decreased at all levels in RVH vs. NL (P

  • An integrated program for 2-D and 3-D analysis of heart wall motion from magnetic resonance imaging
    Computers in Cardiology 1995, 1995
    Co-Authors: L. Axel, Z.a. Fayad, D.l. Kraitchman, D.c. Bloomgarden, C.-n. Chang, A.a. Young
    Abstract:

    Magnetic resonance imaging (MRI) with magnetization tagging provides a non invasive tomographic imaging method for the evaluation of cardiac Function. We have developed an integrated set of programs for the analysis and display of heart wall motion from cardiac MRI. Cardiac wall contours and tag positions can be extracted manually or semiautomatically from the images. The contours can be stacked to calculate Global Function variables, or the relative motion of the tags in the images can be used to calculate the regional 2-D strain. Tag data from orthogonal sets of images can be combined to calculate regional 3-D strain. Display options include static or dynamic displays of scalar and vector or tensor quantities. This integrated program provides a useful means to extract and display cardiac Function data from tagged MRI.