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Sample records for tvd total variation

  1. High-order TVD and TVB linear multistep methods

    NARCIS (Netherlands)

    Ruuth, S.J.; Hundsdorfer, W.

    2004-01-01

    We consider linear multistep methods that possess the TVD (total variation diminishing) or TVB (total variation bounded) properties, or related general monotonicity and boundedness properties. Strict monotonicity or TVD, in terms of arbitrary starting values for the multistep schemes, is only valid

  2. TVD differencing on three-dimensional unstructured meshes with monotonicity-preserving correction of mesh skewness

    Science.gov (United States)

    Denner, Fabian; van Wachem, Berend G. M.

    2015-10-01

    Total variation diminishing (TVD) schemes are a widely applied group of monotonicity-preserving advection differencing schemes for partial differential equations in numerical heat transfer and computational fluid dynamics. These schemes are typically designed for one-dimensional problems or multidimensional problems on structured equidistant quadrilateral meshes. Practical applications, however, often involve complex geometries that cannot be represented by Cartesian meshes and, therefore, necessitate the application of unstructured meshes, which require a more sophisticated discretisation to account for their additional topological complexity. In principle, TVD schemes are applicable to unstructured meshes, however, not all the data required for TVD differencing is readily available on unstructured meshes, and the solution suffers from considerable numerical diffusion as a result of mesh skewness. In this article we analyse TVD differencing on unstructured three-dimensional meshes, focusing on the non-linearity of TVD differencing and the extrapolation of the virtual upwind node. Furthermore, we propose a novel monotonicity-preserving correction method for TVD schemes that significantly reduces numerical diffusion caused by mesh skewness. The presented numerical experiments demonstrate the importance of accounting for the non-linearity introduced by TVD differencing and of imposing carefully chosen limits on the extrapolated virtual upwind node, as well as the efficacy of the proposed method to correct mesh skewness.

  3. Nonlinear Interpolation and Total Variation Diminishing Schemes

    CERN Document Server

    Dubois, François

    2010-01-01

    The Van Leer approach for the approximation of nonlinear scalar conservation laws is studied in one space dimension. The problem can be reduced to a nonlinear interpolation and we propose a convexity property for the interpolated values. We prove that under general hypotheses the method of lines in well posed in $\\ ell^{\\infty} \\cap {\\rm BV} $ and we give precise sufficient conditions to establish that the total variation is diminishing. We observe that the second order accuracy can be maintained even at non sonic extrema. We establish also that both the TVD property and second order accuracy can be maintained after discretization in time with the second order accurate Heun scheme. Numerical illustration for the advection equation is presented.

  4. A CLASS OF TWO-STEP TVD MACCORMACK TYPE NUMERICAL SCHEME FOR MHD EQUATIONS

    Institute of Scientific and Technical Information of China (English)

    FENG Xueshang; WEI Fengsi; ZHONG Dingkun

    2003-01-01

    In this paper, a new numerical scheme of Total Variation Diminishing (TVD) MacCormack type for MagnetoHydroDynamic (MHD) equations is proposed by taking into account of the characteristics such as convergence, stability, resolution. This new scheme is established by solving the MHD equations with a TVD modified MacCormack scheme for the purpose of developing a scheme of quick convergence as well as of TVD property. To show the validation, simplicity and practicability of the scheme for modelling MHD problems, a self-similar Cauchy problem with the discontinuous initial data consisting of constant states, and the collision of two fast MHD shocks, and two-dimensional Orszag and Tang's MHD vortex problem are discussed with the numerical results conforming to the existing results obtained by the Roe type TVD, the high-order Godunov scheme,and Weighted Essentially Non-Oscillatory (WENO) scheme. The numerical tests show that this two-step TVD MacCormack numerical scheme for MHD system is of robust operation in the presence of very strong waves, thin shock fronts, thin contact and slip surface discontinuities.

  5. Simulation of Viscous and Reactive Hypersonic Flows Behaviour in a Shock Tube Facility: TVD Schemes and Flux Limiters Application

    Directory of Open Access Journals (Sweden)

    A. Boulahia

    2014-01-01

    Full Text Available Work performed in this study concerns mainly the analysis and the wisely use of TVD type schemes (total variation diminishing for numerical simulation of reactive flows, these schemes are first presented in scalar equation. Their extension to Euler equations for a reactive gas mixture is conducted through the approximate extended solver of Riemann problem. A comparative study of specific variants of TVD schemes has been made in the case of one-dimensional unsteady flow for an inert and reactive gas mixture, which represents the classical instance of a shock tube. The purpose of this investigation is to highlight the general behaviour (order of accuracy and performance of TVD schemes with various flux limiters for the simulation of reactive flows and in particular, to make possible the capture of the shock wave together with waves expansion for choosing the appropriate scheme to apply eventually in simulation of hypersonic viscous flow in chemical non equilibrium.

  6. Development of High-Resolution Total Variation Diminishing Scheme for Linear Hyperbolic Problems

    Directory of Open Access Journals (Sweden)

    Rabie A. Abu Saleem

    2015-01-01

    Full Text Available A high-resolution, total variation diminishing (TVD stable scheme is derived for scalar hyperbolic problems using the method of flux limiters. The scheme was constructed by combining the 1st-order upwind scheme and the 3rd-order quadratic upstream interpolation scheme (QUICK using new flux limiter function. The new flux limiter function was established by imposing several conditions to ensure the TVD properties of the scheme. For temporal discretization, the theta method was used, and values for the parameter θ were chosen such that the scheme is unconditionally stable. Numerical results are presented for one-dimensional pure advection problems with smooth and discontinuous initial conditions and are compared to those of other known numerical schemes. The results show that the proposed numerical method is stable and of higher order than other common schemes.

  7. Evolution of Debris of a Tidally Disrupted Star by a Massive Black Hole Development of a Hybrid Scheme of the SPH and TVD Methods

    CERN Document Server

    Lee, H M; Lee, Hyung Mok; Kim, Sungsoo S.

    1996-01-01

    The evolution of the stellar debris after tidal disruption due to the super massive black hole's tidal force is difficult to solve numerically because of the large dynamical range of the problem. We developed an SPH (Smoothed Particle Hydrodynamics) - TVD (Total Variation Diminishing) hybrid code in which the SPH is used to cover a widely spread debris and the TVD is used to compute the stream collision more accurately. While the code in the present form is not sufficient to obtain desired resoultion, it could provide a useful tool in studying the aftermath of the stellar disruption by a massive black hole.

  8. Total variation regularization with bounded linear variations

    Science.gov (United States)

    Makovetskii, Artyom; Voronin, Sergei; Kober, Vitaly

    2016-09-01

    One of the most known techniques for signal denoising is based on total variation regularization (TV regularization). A better understanding of TV regularization is necessary to provide a stronger mathematical justification for using TV minimization in signal processing. In this work, we deal with an intermediate case between one- and two-dimensional cases; that is, a discrete function to be processed is two-dimensional radially symmetric piecewise constant. For this case, the exact solution to the problem can be obtained as follows: first, calculate the average values over rings of the noisy function; second, calculate the shift values and their directions using closed formulae depending on a regularization parameter and structure of rings. Despite the TV regularization is effective for noise removal; it often destroys fine details and thin structures of images. In order to overcome this drawback, we use the TV regularization for signal denoising subject to linear signal variations are bounded.

  9. Edge adaptive directional total variation

    Directory of Open Access Journals (Sweden)

    Hua Zhang

    2013-11-01

    Full Text Available The directional total variation (DTV model has been proposed very recently for image denoising. However, the DTV model works well when there is just one dominant direction in the image. In this Letter, the authors propose to make the DTV model adaptive to image edge direction so that the proposed model can handle images with several dominant directions. Experiment and comparison show the effectiveness of the proposed method.

  10. A TVD-WAF-based hybrid finite volume and finite difference scheme for nonlinearly dispersive wave equations

    Directory of Open Access Journals (Sweden)

    Jing Yin

    2015-07-01

    Full Text Available A total variation diminishing-weighted average flux (TVD-WAF-based hybrid numerical scheme for the enhanced version of nonlinearly dispersive Boussinesq-type equations was developed. The one-dimensional governing equations were rewritten in the conservative form and then discretized on a uniform grid. The finite volume method was used to discretize the flux term while the remaining terms were approximated with the finite difference method. The second-order TVD-WAF method was employed in conjunction with the Harten-Lax-van Leer (HLL Riemann solver to calculate the numerical flux, and the variables at the cell interface for the local Riemann problem were reconstructed via the fourth-order monotone upstream-centered scheme for conservation laws (MUSCL. The time marching scheme based on the third-order TVD Runge-Kutta method was used to obtain numerical solutions. The model was validated through a series of numerical tests, in which wave breaking and a moving shoreline were treated. The good agreement between the computed results, documented analytical solutions, and experimental data demonstrates the correct discretization of the governing equations and high accuracy of the proposed scheme, and also conforms the advantages of the proposed shock-capturing scheme for the enhanced version of the Boussinesq model, including the convenience in the treatment of wave breaking and moving shorelines and without the need for a numerical filter.

  11. The role of computational fluid dynamics in aeronautical engineering (5). Improvements and applications of implicit TVD finite volume code

    Science.gov (United States)

    Shima, Eiji; Yoshida, Kenji; Amano, Kanichi

    1987-11-01

    An automatic grid generator for multiple element airfoils was developed and the existing implicit Total Variation Diminishing (TVD) finite volume code was improved in both accuracy and efficiency, in order to make the Navier-Stokes solver a practical design tool for high lift devices. Utilizing these codes, Navier-Stokes analysis of the single slotted flap was carried out. The automatic grid generator utilizes the elliptic equation solver using the finite difference method combined with the panel method. The flow field is divided into subregions by the dividing stream lines which are calculated by the panel method and the computational grid in each subregion is generated by solving the elliptic equations (Thompson's method). Since the panel method can solve the potential flow around any number of arbitrary shaped bodies, this grid generator can generate a H-type computational grid around such bodies automatically. To obtain a high accuracy on a rapidly stretching grid, the flow solver uses the TVD formulation containing an explicit treatment of nonuniform grid spacing. Converging rate and numerical stability of the flow solver is augmented by the relaxation approach using Symmetric Point Gauss Seidel method in matrix inversion process which is necessary for an implicit scheme.

  12. A solver for the two-phase two-fluid model based on high-resolution total variation diminishing scheme

    Energy Technology Data Exchange (ETDEWEB)

    Abu Saleem, Rabie A., E-mail: raabusaleem@just.edu.jo [Nuclear Engineering Department, Jordan University of Science and Technology, P.O. Box 3030, Irbid 22110 (Jordan); Kozlowski, Tomasz, E-mail: txk@illinois.edu [Department of Nuclear, Plasma and Radiological Engineering, University of Illinois at Urbana-Champaign, 216 Talbot Laboratory, 104 S. Wright St., Urbana, IL 61801 (United States); Shrestha, Rijan, E-mail: rijan.shrestha@intel.com [Portland Technology Development, Intel Corporation, 2501 NW 229th Ave Hillsboro OR 97124 (United States)

    2016-05-15

    Highlights: • The two-fluid model and the challenges associated with its numerical modeling are investigated. • A high-order solver based on flux limiter schemes and the theta method was developed. • The solver was compared to existing thermal hydraulics codes used in nuclear industry. • The solver was shown to handle fast transients with discontinuities and phase change. - Abstract: Finite volume techniques with staggered mesh are used to develop a new numerical solver for the one-dimensional two-phase two-fluid model using a high-resolution, Total Variation Diminishing (TVD) scheme. The solver is implemented to analyze numerical benchmark problems for verification and testing its abilities to handle discontinuities and fast transients with phase change. Convergence rates are investigated by comparing numerical results to analytical solutions available in literature for the case of the faucet flow problem. The solver based on a new TVD scheme is shown to exhibit higher-order of accuracy compared to other numerical schemes. Mass errors are also examined when phase change occurs for the shock tube problem, and compared to those of the 1st-order upwind scheme implemented in the nuclear thermal-hydraulics code TRACE. The solver is shown to exhibit numerical stability when applied to problems with discontinuous solutions and results of the new solver are free of spurious oscillations.

  13. Chambolle's Projection Algorithm for Total Variation Denoising

    Directory of Open Access Journals (Sweden)

    Joan Duran

    2013-12-01

    Full Text Available Denoising is the problem of removing the inherent noise from an image. The standard noise model is additive white Gaussian noise, where the observed image f is related to the underlying true image u by the degradation model f=u+n, and n is supposed to be at each pixel independently and identically distributed as a zero-mean Gaussian random variable. Since this is an ill-posed problem, Rudin, Osher and Fatemi introduced the total variation as a regularizing term. It has proved to be quite efficient for regularizing images without smoothing the boundaries of the objects. This paper focuses on the simple description of the theory and on the implementation of Chambolle's projection algorithm for minimizing the total variation of a grayscale image. Furthermore, we adapt the algorithm to the vectorial total variation for color images. The implementation is described in detail and its parameters are analyzed and varied to come up with a reliable implementation.

  14. On the total variation dictionary model.

    Science.gov (United States)

    Zeng, Tieyong; Ng, Michael K

    2010-03-01

    The goal of this paper is to provide a theoretical study of a total variation (TV) dictionary model. Based on the properties of convex analysis and bounded variation functions, the existence of solutions of the TV dictionary model is proved. We then show that the dual form of the model can be given by the minimization of the sum of the l(1) -norm of the dual solution and the Bregman distance between the curvature of the primal solution and the subdifferential of TV norm of the dual solution. This theoretical result suggests that the dictionary must represent sparsely the curvatures of solution image in order to obtain a better denoising performance.

  15. Asymptotic Behaviour of Total Generalised Variation

    KAUST Repository

    Papafitsoros, Konstantinos

    2015-01-01

    © Springer International Publishing Switzerland 2015. The recently introduced second order total generalised variation functional TGV2 β,α has been a successful regulariser for image processing purposes. Its definition involves two positive parameters α and β whose values determine the amount and the quality of the regularisation. In this paper we report on the behaviour of TGV2 β,α in the cases where the parameters α, β as well as their ratio β/α becomes very large or very small. Among others, we prove that for sufficiently symmetric two dimensional data and large ratio β/α, TGV2 β,α regularisation coincides with total variation (TV) regularization

  16. Total variation projection with first order schemes.

    Science.gov (United States)

    Fadili, Jalal M; Peyre, Gabriel

    2011-03-01

    This article proposes a new algorithm to compute the projection on the set of images whose total variation is bounded by a constant. The projection is computed through a dual formulation that is solved by first order non-smooth optimization methods. This yields an iterative algorithm that applies iterative soft thresholding to the dual vector field, and for which we establish convergence rate on the primal iterates. This projection algorithm can then be used as a building block in a variety of applications such as solving inverse problems under a total variation constraint, or for texture synthesis. Numerical results are reported to illustrate the usefulness and potential applicability of our TV projection algorithm on various examples including denoising, texture synthesis, inpainting, deconvolution and tomography problems. We also show that our projection algorithm competes favorably with state-of-the-art TV projection methods in terms of convergence speed.

  17. Controlling inclination in rotary mode in tight TVD corridors using a 2-dimensional steerable system

    Energy Technology Data Exchange (ETDEWEB)

    Rasheed, W. [Andergauge Ltd., Dubai (United Arab Emirates)

    2000-11-01

    The use of a 2D rotary steerable system to control the inclination of true vertical depth (TVD) and horizontal wells was discussed. The system was introduced in 1986 and has since been used successfully in more than 4,500 sections and 500 horizontal wells worldwide. Directional corrections are unlikely with the use of this system. The system can often drill to total depth in a single bit run. As well bore inclination increases, bit walk becomes less significant. It was concluded that the 2D rotary steerable system is capable of drilling horizontal sections effectively and efficiently. It can meet tight TVD corridor objectives with an accuracy of {+-}2 feet. It also has other benefits regarding hole quality. 11 refs., 5 tabs.

  18. Total-variation regularization with bound constraints

    Energy Technology Data Exchange (ETDEWEB)

    Chartrand, Rick [Los Alamos National Laboratory; Wohlberg, Brendt [Los Alamos National Laboratory

    2009-01-01

    We present a new algorithm for bound-constrained total-variation (TV) regularization that in comparison with its predecessors is simple, fast, and flexible. We use a splitting approach to decouple TV minimization from enforcing the constraints. Consequently, existing TV solvers can be employed with minimal alteration. This also makes the approach straightforward to generalize to any situation where TV can be applied. We consider deblurring of images with Gaussian or salt-and-pepper noise, as well as Abel inversion of radiographs with Poisson noise. We incorporate previous iterative reweighting algorithms to solve the TV portion.

  19. Total Variation and Tomographic Imaging from Projections

    DEFF Research Database (Denmark)

    Hansen, Per Christian; Jørgensen, Jakob Heide

    2011-01-01

    Total Variation (TV) regularization is a powerful technique for image reconstruction tasks such as denoising, in-painting, and deblurring, because of its ability to produce sharp edges in the images. In this talk we discuss the use of TV regularization for tomographic imaging, where we compute a 2D...... incorporates our prior information about the solution and thus compensates for the loss of accuracy in the data. A consequence is that smaller data acquisition times can be used, thus reducing a patients exposure to X-rays in medical scanning and speeding up non-destructive measurements in materials science....

  20. UPRE method for total variation parameter selection

    Energy Technology Data Exchange (ETDEWEB)

    Wohlberg, Brendt [Los Alamos National Laboratory; Lin, Youzuo [Los Alamos National Laboratory

    2008-01-01

    Total Variation (TV) Regularization is an important method for solving a wide variety of inverse problems in image processing. In order to optimize the reconstructed image, it is important to choose the optimal regularization parameter. The Unbiased Predictive Risk Estimator (UPRE) has been shown to give a very good estimate of this parameter for Tikhonov Regularization. In this paper we propose an approach to extend UPRE method to the TV problem. However, applying the extended UPRE is impractical in the case of inverse problems such as de blurring, due to the large scale of the associated linear problem. We also propose an approach to reducing the large scale problem to a small problem, significantly reducing computational requirements while providing a good approximation to the original problem.

  1. Total Variation Inpainting using Split Bregman

    Directory of Open Access Journals (Sweden)

    Pascal Getreuer

    2012-07-01

    Full Text Available Given an image where a specified region is unknown, image inpainting or image completion is the problem of inferring the image content in this region. Traditional retouching or inpainting is the practice of restoring aged artwork, where damaged or missing portions are repainted based on the surrounding content to approximate the original appearance. In the context of digital images, inpainting is used to restore regions of an image that are corrupted by noise or where the data is missing. Inpainting is also used to solve disocclusion, to estimate the scene behind an obscuring foreground object. A popular use of digital inpainting is object removal, for example, to remove a trashcan that disrupts a scene of otherwise natural beauty. Inpainting is an interpolation problem, filling the unknown region with a condition to agree with the known image on the boundary. A classical solution for such an interpolation is to solve Laplace's equation. However, Laplace's equation is usually unsatisfactory for images since it is overly smooth. It cannot recover a step edge passing through the region. Total variation (TV regularization is an effective inpainting technique which is capable of recovering sharp edges under some conditions (these conditions will be explained. The use of TV regularization was originally developed for image denoising by Rudin, Osher, and Fatemi and then applied to inpainting by Chan and Shen. TV-regularized inpainting does not create texture, the method is limited to inpainting the geometric structure.

  2. Total Variation Deconvolution using Split Bregman

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    Pascal Getreuer

    2012-07-01

    Full Text Available Deblurring is the inverse problem of restoring an image that has been blurred and possibly corrupted with noise. Deconvolution refers to the case where the blur to be removed is linear and shift-invariant so it may be expressed as a convolution of the image with a point spread function. Convolution corresponds in the Fourier domain to multiplication, and deconvolution is essentially Fourier division. The challenge is that since the multipliers are often small for high frequencies, direct division is unstable and plagued by noise present in the input image. Effective deconvolution requires a balance between frequency recovery and noise suppression. Total variation (TV regularization is a successful technique for achieving this balance in deblurring problems. It was originally developed for image denoising by Rudin, Osher, and Fatemi and then applied to deconvolution by Rudin and Osher. In this article, we discuss TV-regularized deconvolution with Gaussian noise and its efficient solution using the split Bregman algorithm of Goldstein and Osher. We show a straightforward extension for Laplace or Poisson noise and develop empirical estimates for the optimal value of the regularization parameter λ.

  3. Some Variations on Total Variation-Based Image Smoothing

    Science.gov (United States)

    2009-03-01

    influential paper, Rudin, Osher, and Fatemi [23] suggested using the bounded variation seminorm to smooth images. The functional proposed in their work has...unit square I = [0, 1]2, where the bounded variation seminorm is defined as |f |BV(I) := ∫ I |Df(x)| dx := sup {∫ I f ∇ · p ∣∣∣ p : I → R2,(1) p ∈ C1(I...approximation to the ROF functional. In Section 3, we propose a new formulation of an upwind finite-difference approximation to the bounded variation seminorm

  4. Total Variation and Multisymplectic Structure for CNLS System

    Institute of Scientific and Technical Information of China (English)

    SUN Jian-Qiang; QIN Meng-Zhao; LIU Ting-Ting

    2006-01-01

    The relation between the total variation of classical field theory and the multisymplectic structure is shown. Then the multisymplectic structure and the corresponding multisymplectic conservation of the coupled nonlinear Schrodinger system are obtained directly from the variational principle.

  5. Sign variation, the Grassmannian, and total positivity

    CERN Document Server

    Karp, Steven N

    2016-01-01

    The totally nonnegative Grassmannian is the set of k-dimensional subspaces V of R^n whose nonzero Pluecker coordinates all have the same sign. Gantmakher and Krein (1950) and Schoenberg and Whitney (1951) independently showed that V is totally nonnegative iff every vector in V, when viewed as a sequence of n numbers and ignoring any zeros, changes sign at most k-1 times. We generalize this result from the totally nonnegative Grassmannian to the entire Grassmannian, showing that if V is generic (i.e. has no zero Pluecker coordinates), then the vectors in V change sign at most m times iff certain sequences of Pluecker coordinates of V change sign at most m-k+1 times. We also give an algorithm which, given a non-generic V whose vectors change sign at most m times, perturbs V into a generic subspace whose vectors also change sign at most m times. We deduce that among all V whose vectors change sign at most m times, the generic subspaces are dense. These results generalize to oriented matroids. As an application o...

  6. A TVD SCHEME FOR INCOMPRESSIBLE FLOW COUPLED WITH DIFFERENT TURBULENCE MODLES ON A GROUND- MOUNTED SQUARE-RIB FLOW

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A finite-difference Total Variation Diminishing (TVD) numerical simulation model for coupling the Reynolds Averaged Navier-Stokes (RANS) equations, pressure-relative continuity equation and various k-ε turbulence models was developed to solve the incompressible flow based on the pseudo-compressibility method. The hyperbolicity of all these equations was studied and the discretization of the fully coupling equations with all the primal variables and source terms were made in this article. Numerical simulation for modeling the flow around a ground-mounted square rib was implemented and validated by comparing with the published wind tunnel experimental data. It is shown that such a numerical simulation method with a proper turbulence model has a very good accuracy to simulate the flow around a surface-mounted rib. It is concluded that the Renormalization Group (RNG) and Chen-Kim k-ε turbulence models have much better ability to predict the characteristics of the vortex structure and flow separation than the standard k-ε model.

  7. Development of a new numerical method for visco-elastic flows using the GSMAC-method and the MUSCL-TVD method. Flows of Maxwell fluid through planer abrupt contraction; Kosei hoteishiki ni TVD gata MUSCL ho wo mochiita GSMAC ho ni yoru nendansei ryutai no kaiseki ni tekishita scheme kaihatsu. Maxwell ryutai no kyushuku shoheibannai nagare ni yoru kensho

    Energy Technology Data Exchange (ETDEWEB)

    Fujieda, T.; Tanahashi, T.; Okada, A. [Keio University, Tokyo (Japan). Faculty of Science and Technology; Kato, Y. [Asahi Glass Co. Ltd., Tokyo (Japan)

    1997-06-25

    In this paper, we propose a new GSMAC-FEM (generalized simplified marker and cell-finite element method) which is suited to the numerical analysis of visco-elastic fluids. The equation of continuity and the equation of momentum are solved by the GSMAC-FEM algorithm and the constitutive equation is solved by the finite volume method. This scheme employs the third order MUSCL (Monotone Upstream-centered Schemes for Conservation Law) in order to guarantee the absence of spurious oscillation near the steep gradients of the variable. This method uses a minmod limiter in order to satisfy the TVD (Total Variation Diminishing) condition. The present method employs the simultaneous relaxation of velocity and pressure for the incompressible condition. The flows of Maxwell fluid through two-dimensional planer abrupt contraction are calculated by the present method and the effects the Weissenberg number and the Reynolds number are discussed. 13 refs., 12 figs.

  8. Summertime total ozone variations over middle and polar latitudes

    OpenAIRE

    Fioletov, Vitali E.; Shepherd, Theodore G.

    2005-01-01

    The statistical relationship between springtime and summertime ozone over middle and polar latitudes is analyzed using zonally averaged total ozone data. Shortterm variations in springtime midlatitude ozone demonstrate only a modest correlation with springtime polar ozone variations. However by early summer, ozone variations throughout the extratropics are highly correlated. Analysis of correlation functions indicates that springtime midlatitude ozone, not polar ozone, is the best predictor f...

  9. On the Total Variation Distance of Semi-Markov Chains

    DEFF Research Database (Denmark)

    Bacci, Giorgio; Bacci, Giovanni; Larsen, Kim Guldstrand

    2015-01-01

    linear real-time specifications. Specifically, we prove that the total variation between two SMCs coincides with the maximal difference w.r.t. the likelihood of satisfying arbitrary MTL formulas or omega-languages recognized by timed automata. Computing this distance (i.e., solving its threshold problem......Semi-Markov chains (SMCs) are continuous-time probabilistic transition systems where the residence time on states is governed by generic distributions on the positive real line. This paper shows the tight relation between the total variation distance on SMCs and their model checking problem over...

  10. A Unidirectional Total Variation and Second-Order Total Variation Model for Destriping of Remote Sensing Images

    Directory of Open Access Journals (Sweden)

    Min Wang

    2017-01-01

    Full Text Available Remote sensing images often suffer from stripe noise, which greatly degrades the image quality. Destriping of remote sensing images is to recover a good image from the image containing stripe noise. Since the stripes in remote sensing images have a directional characteristic (horizontal or vertical, the unidirectional total variation has been used to consider the directional information and preserve the edges. The remote sensing image contaminated by heavy stripe noise always has large width stripes and the pixels in the stripes have low correlations with the true pixels. On this occasion, the destriping process can be viewed as inpainting the wide stripe domains. In many works, high-order total variation has been proved to be a powerful tool to inpainting wide domains. Therefore, in this paper, we propose a variational destriping model that combines unidirectional total variation and second-order total variation regularization to employ the directional information and handle the wide stripes. In particular, the split Bregman iteration method is employed to solve the proposed model. Experimental results demonstrate the effectiveness of the proposed method.

  11. Mixed Gaussian-Impulse Noise Image Restoration Via Total Variation

    Science.gov (United States)

    2012-05-01

    pp. 402–407. [12] L. Rudin , S. Osher, and E. Fatemi, “Nonlinear total vari- ation based noise removal algorithms.,” Physica D. Non- lin. Phenomena...variation regularization in positron emission tomography,” UCLA CAM Report 98-48, 1998, CAM Report 98-48, UCLA. [16] S. Osher, N. Paragios, L. Rudin , and P

  12. Solving the uncalibrated photometric stereo problem using total variation

    DEFF Research Database (Denmark)

    Quéau, Yvain; Lauze, Francois Bernard; Durou, Jean-Denis

    2013-01-01

    In this paper we propose a new method to solve the problem of uncalibrated photometric stereo, making very weak assumptions on the properties of the scene to be reconstructed. Our goal is to solve the generalized bas-relief ambiguity (GBR) by performing a total variation regularization of both th...

  13. Total Variation Regularization for Functions with Values in a Manifold

    KAUST Repository

    Lellmann, Jan

    2013-12-01

    While total variation is among the most popular regularizers for variational problems, its extension to functions with values in a manifold is an open problem. In this paper, we propose the first algorithm to solve such problems which applies to arbitrary Riemannian manifolds. The key idea is to reformulate the variational problem as a multilabel optimization problem with an infinite number of labels. This leads to a hard optimization problem which can be approximately solved using convex relaxation techniques. The framework can be easily adapted to different manifolds including spheres and three-dimensional rotations, and allows to obtain accurate solutions even with a relatively coarse discretization. With numerous examples we demonstrate that the proposed framework can be applied to variational models that incorporate chromaticity values, normal fields, or camera trajectories. © 2013 IEEE.

  14. On total variation flows with H-1 penalty

    Science.gov (United States)

    Wunderli, Thomas

    2012-09-01

    We analyze the time flow of a version of the Rudin-Osher-Fatemi [5] model for image restoration using the bounded variation semi-norm with H-1 penalty. We will define an appropriate weak solution of the time flow and prove existence and uniqueness of the solution using the method of semigroups, as used by Andreu, Ballester, Caselles, Mazön [1] for their analysis of total variation flow without penalty. We also note two interesting properties for the time solutions.

  15. Global distribution of total ozone and lower stratospheric temperature variations

    Directory of Open Access Journals (Sweden)

    W. Steinbrecht

    2003-01-01

    Full Text Available This study gives an overview of interannual variations of total ozone and 50 hPa temperature. It is based on newer and longer records from the 1979 to 2001 Total Ozone Monitoring Spectrometer (TOMS and Solar Backscatter Ultraviolet (SBUV instruments, and on US National Center for Environmental Prediction (NCEP reanalyses. Multiple linear least squares regression is used to attribute variations to various natural and anthropogenic explanatory variables. Usually, maps of total ozone and 50 hPa temperature variations look very similar, reflecting a very close coupling between the two. As a rule of thumb, a 10 Dobson Unit (DU change in total ozone corresponds to a 1 K change of 50 hPa temperature. Large variations come from the linear trend term, up to -30 DU or -1.5 K/decade, from terms related to polar vortex strength, up to 50 DU or 5 K (typical, minimum to maximum, from tropospheric meteorology, up to 30 DU or 3 K, or from the Quasi-Biennial Oscillation (QBO, up to 25 DU or 2.5 K. The 11-year solar cycle, up to 25 DU or 2.5 K, or El Niño/Southern Oscillation (ENSO, up to 10 DU or 1 K, are contributing smaller variations. Stratospheric aerosol after the 1991 Pinatubo eruption lead to warming up to 3 K at low latitudes and to ozone depletion up to 40 DU at high latitudes. Variations attributed to QBO, polar vortex strength, and to a lesser degree to ENSO, exhibit an inverse correlation between low latitudes and higher latitudes. Variations related to the solar cycle or 400 hPa temperature, however, have the same sign over most of the globe. Variations are usually zonally symmetric at low and mid-latitudes, but asymmetric at high latitudes. There, position and strength of the stratospheric anti-cyclones over the Aleutians and south of Australia appear to vary with the phases of solar cycle, QBO or ENSO.

  16. Performance Comparison of Total Variation based Image Regularization Algorithms

    Directory of Open Access Journals (Sweden)

    Kamalaveni Vanjigounder

    2016-07-01

    Full Text Available The mathematical approach calculus of variation is commonly used to find an unknown function that minimizes or maximizes the functional. Retrieving the original image from the degraded one, such problems are called inverse problems. The most basic example for inverse problem is image denoising. Variational methods are formulated as optimization problems and provides a good solution to image denoising. Three such variational methods Tikhonov model, ROF model and Total Variation-L1 model for image denoising are studied and implemented. Performance of these variational algorithms are analyzed for different values of regularization parameter. It is found that small value of regularization parameter causes better noise removal whereas large value of regularization parameter preserves well sharp edges. The Euler’s Lagrangian equation corresponding to an energy functional used in variational methods is solved using gradient descent method and the resulting partial differential equation is solved using Euler’s forward finite difference method. The quality metrics are computed and the results are compared in this paper. 

  17. An algorithm for total variation regularized photoacoustic imaging

    DEFF Research Database (Denmark)

    Dong, Yiqiu; Görner, Torsten; Kunis, Stefan

    2014-01-01

    Recovery of image data from photoacoustic measurements asks for the inversion of the spherical mean value operator. In contrast to direct inversion methods for specific geometries, we consider a semismooth Newton scheme to solve a total variation regularized least squares problem. During the iter...... the iteration, each matrix vector multiplication is realized in an efficient way using a recently proposed spectral discretization of the spherical mean value operator. All theoretical results are illustrated by numerical experiments.......Recovery of image data from photoacoustic measurements asks for the inversion of the spherical mean value operator. In contrast to direct inversion methods for specific geometries, we consider a semismooth Newton scheme to solve a total variation regularized least squares problem. During...

  18. Speckle reduction via higher order total variation approach.

    Science.gov (United States)

    Wensen Feng; Hong Lei; Yang Gao

    2014-04-01

    Multiplicative noise (also known as speckle) reduction is a prerequisite for many image-processing tasks in coherent imaging systems, such as the synthetic aperture radar. One approach extensively used in this area is based on total variation (TV) regularization, which can recover significantly sharp edges of an image, but suffers from the staircase-like artifacts. In order to overcome the undesirable deficiency, we propose two novel models for removing multiplicative noise based on total generalized variation (TGV) penalty. The TGV regularization has been mathematically proven to be able to eliminate the staircasing artifacts by being aware of higher order smoothness. Furthermore, an efficient algorithm is developed for solving the TGV-based optimization problems. Numerical experiments demonstrate that our proposed methods achieve state-of-the-art results, both visually and quantitatively. In particular, when the image has some higher order smoothness, our methods outperform the TV-based algorithms.

  19. Random noise attenuation using an improved anisotropic total variation regularization

    Science.gov (United States)

    Gemechu, Diriba; Yuan, Huan; Ma, Jianwei

    2017-09-01

    In seismic data processing, attenuation of random noise from the observed data is the basic step which improves the signal-to-noise ratio (SNR) of seismic data. In this paper, we proposed an anisotropic total bounded variation regularization approach to attenuate noise. An improved constraint convex optimization model is formulated for this approach and then the split Bregman algorithm is used to solve the optimization model. Generalized cross validation (GCV) technique is used to estimate the regularization parameter. Synthetic and real seismic data are considered to show the out performance of the proposed method in terms of event-preserving denoising, in comparison with FX deconvolution, shearlet hard thresholding, and anisotropic total variation methods. The numerical results indicate that the proposed method effectively attenuates random noise by preserving the structure and important features of seismic data.

  20. Variational total energies from {Phi} - and {Psi}- derivable theories

    Energy Technology Data Exchange (ETDEWEB)

    Almbladh, C.O.; Von Barth, U.; Van Leeuwen, R. [Department of Theoretical Physics, Lund University, Lund (Sweden)

    1998-12-31

    Starting from many-body perturbation theory we have constructed a new variational expression for the total energy of many-electron systems. This expression is a functional of two independent variables, the one-electron Green function and the screened Coulomb interaction. The new functional as well as a much older variational expression by Luttinger and Ward (LW) are tested on the interacting electron gas. Both functionals yield extraordinary accurate total energies although the new functional requires a much cruder input and is therefore easier to apply to more realistic systems. When the self-consistent Green`s function of the GWA is used in the evaluations, both expressions give identical results close to those of elaborate Monte-Carlo calculations. (Copyright (1998) World Scientific Publishing Co. Pte. Ltd) 14 refs.,2 fig., email addresses: coa/teorfys.lu.se; barth/teorfys.lu.se; rvl/teorfys.lu.se

  1. A convergent overlapping domain decomposition method for total variation minimization

    KAUST Repository

    Fornasier, Massimo

    2010-06-22

    In this paper we are concerned with the analysis of convergent sequential and parallel overlapping domain decomposition methods for the minimization of functionals formed by a discrepancy term with respect to the data and a total variation constraint. To our knowledge, this is the first successful attempt of addressing such a strategy for the nonlinear, nonadditive, and nonsmooth problem of total variation minimization. We provide several numerical experiments, showing the successful application of the algorithm for the restoration of 1D signals and 2D images in interpolation/inpainting problems, respectively, and in a compressed sensing problem, for recovering piecewise constant medical-type images from partial Fourier ensembles. © 2010 Springer-Verlag.

  2. Total variation denoising of interseismic deformation in western North America

    Science.gov (United States)

    Evans, E. L.; Meade, B. J.

    2012-12-01

    Geodetic observations of interseismic deformation provide constraints on microplate rotations, earthquake cycle processes, and slip partitioning across the Pacific-North America plate boundary. These measurements may be interpreted using block models, in which the upper crust is divided into microplates bounded by mapped faults. The number and geometry of microplates are typically defined with boundaries representing a limited sub-set of the large number of potentially seismogenic faults. An alternative approach is to include all possible faults in a dense array of microplates, and then deterministically estimate the boundaries at which strain is localized. This is possible with a regularization technique called total variation denoising (TVDN), which simultaneously minimizes of the l2-norm of the data residuals and l1-norm of the variation in the estimated state vector. Applied to three-dimensional spherical block models, TVDN reduces the total variation between estimated rotation vectors, creating groups of microplates that rotate together as larger blocks, and therefore localizing fault slip on the boundaries of these larger blocks. Here we develop a block model comprised of hundreds of microplates based on detailed fault maps, and deterministically identify the kinematically most important faults in western North America using TVDN regularization.

  3. Moving object detection via low-rank total variation regularization

    Science.gov (United States)

    Wang, Pengcheng; Chen, Qian; Shao, Na

    2016-09-01

    Moving object detection is a challenging task in video surveillance. Recently proposed Robust Principal Component Analysis (RPCA) can recover the outlier patterns from the low-rank data under some mild conditions. However, the l-penalty in RPCA doesn't work well in moving object detection because the irrepresentable condition is often not satisfied. In this paper, a method based on total variation (TV) regularization scheme is proposed. In our model, image sequences captured with a static camera are highly related, which can be described using a low-rank matrix. Meanwhile, the low-rank matrix can absorb background motion, e.g. periodic and random perturbation. The foreground objects in the sequence are usually sparsely distributed and drifting continuously, and can be treated as group outliers from the highly-related background scenes. Instead of l-penalty, we exploit the total variation of the foreground. By minimizing the total variation energy, the outliers tend to collapse and finally converge to be the exact moving objects. The TV-penalty is superior to the l-penalty especially when the outlier is in the majority for some pixels, and our method can estimate the outlier explicitly with less bias but higher variance. To solve the problem, a joint optimization function is formulated and can be effectively solved through the inexact Augmented Lagrange Multiplier (ALM) method. We evaluate our method along with several state-of-the-art approaches in MATLAB. Both qualitative and quantitative results demonstrate that our proposed method works effectively on a large range of complex scenarios.

  4. Image Denoising Using Total Variation Model Guided by Steerable Filter

    Directory of Open Access Journals (Sweden)

    Wenxue Zhang

    2014-01-01

    Full Text Available We propose an adaptive total variation (TV model by introducing the steerable filter into the TV-based diffusion process for image filtering. The local energy measured by the steerable filter can effectively characterize the object edges and ramp regions and guide the TV-based diffusion process so that the new model behaves like the TV model at edges and leads to linear diffusion in flat and ramp regions. This way, the proposed model can provide a better image processing tool which enables noise removal, edge-preserving, and staircase suppression.

  5. A New Algorithm for Total Variation Based Image Denoising

    Institute of Scientific and Technical Information of China (English)

    Yi-ping XU

    2012-01-01

    We propose a new algorithm for the total variation based on image denoising problem.The split Bregman method is used to convert an unconstrained minimization denoising problem to a linear system in the outer iteration.An algebraic multi-grid method is applied to solve the linear system in the inner iteration.Furthermore,Krylov subspace acceleration is adopted to improve convergence in the outer iteration.Numerical experiments demonstrate that this algorithm is efficient even for images with large signal-to-noise ratio.

  6. TICMR: Total Image Constrained Material Reconstruction via Nonlocal Total Variation Regularization for Spectral CT.

    Science.gov (United States)

    Liu, Jiulong; Ding, Huanjun; Molloi, Sabee; Zhang, Xiaoqun; Gao, Hao

    2016-12-01

    This work develops a material reconstruction method for spectral CT, namely Total Image Constrained Material Reconstruction (TICMR), to maximize the utility of projection data in terms of both spectral information and high signal-to-noise ratio (SNR). This is motivated by the following fact: when viewed as a spectrally-integrated measurement, the projection data can be used to reconstruct a total image without spectral information, which however has a relatively high SNR; when viewed as a spectrally-resolved measurement, the projection data can be utilized to reconstruct the material composition, which however has a relatively low SNR. The material reconstruction synergizes material decomposition and image reconstruction, i.e., the direct reconstruction of material compositions instead of a two-step procedure that first reconstructs images and then decomposes images. For material reconstruction with high SNR, we propose TICMR with nonlocal total variation (NLTV) regularization. That is, first we reconstruct a total image using spectrally-integrated measurement without spectral binning, and build the NLTV weights from this image that characterize nonlocal image features; then the NLTV weights are incorporated into a NLTV-based iterative material reconstruction scheme using spectrally-binned projection data, so that these weights serve as a high-SNR reference to regularize material reconstruction. Note that the nonlocal property of NLTV is essential for material reconstruction, since material compositions may have significant local intensity variations although their structural information is often similar. In terms of solution algorithm, TICMR is formulated as an iterative reconstruction method with the NLTV regularization, in which the nonlocal divergence is utilized based on the adjoint relationship. The alternating direction method of multipliers is developed to solve this sparsity optimization problem. The proposed TICMR method was validated using both simulated

  7. Continuum Limit of Total Variation on Point Clouds

    Science.gov (United States)

    García Trillos, Nicolás; Slepčev, Dejan

    2016-04-01

    We consider point clouds obtained as random samples of a measure on a Euclidean domain. A graph representing the point cloud is obtained by assigning weights to edges based on the distance between the points they connect. Our goal is to develop mathematical tools needed to study the consistency, as the number of available data points increases, of graph-based machine learning algorithms for tasks such as clustering. In particular, we study when the cut capacity, and more generally total variation, on these graphs is a good approximation of the perimeter (total variation) in the continuum setting. We address this question in the setting of Γ-convergence. We obtain almost optimal conditions on the scaling, as the number of points increases, of the size of the neighborhood over which the points are connected by an edge for the Γ-convergence to hold. Taking of the limit is enabled by a transportation based metric which allows us to suitably compare functionals defined on different point clouds.

  8. Geometric properties of solutions to the total variation denoising problem

    Science.gov (United States)

    Chambolle, Antonin; Duval, Vincent; Peyré, Gabriel; Poon, Clarice

    2017-01-01

    This article studies the denoising performance of total variation (TV) image regularization. More precisely, we study geometrical properties of the solution to the so-called Rudin-Osher-Fatemi total variation denoising method. The first contribution of this paper is a precise mathematical definition of the ‘extended support’ (associated to the noise-free image) of TV denoising. It is intuitively the region which is unstable and will suffer from the staircasing effect. We highlight in several practical cases, such as the indicator of convex sets, that this region can be determined explicitly. Our second and main contribution is a proof that the TV denoising method indeed restores an image which is exactly constant outside a small tube surrounding the extended support. The radius of this tube shrinks toward zero as the noise level vanishes, and we are able to determine, in some cases, an upper bound on the convergence rate. For indicators of so-called ‘calibrable’ sets (such as disks or properly eroded squares), this extended support matches the edges, so that discontinuities produced by TV denoising cluster tightly around the edges. In contrast, for indicators of more general shapes or for complicated images, this extended support can be larger. Beside these main results, our paper also proves several intermediate results about fine properties of TV regularization, in particular for indicators of calibrable and convex sets, which are of independent interest.

  9. Nonlocal Total Variation Subpixel Mapping for Hyperspectral Remote Sensing Imagery

    Directory of Open Access Journals (Sweden)

    Ruyi Feng

    2016-03-01

    Full Text Available Subpixel mapping is a method of enhancing the spatial resolution of images, which involves dividing a mixed pixel into subpixels and assigning each subpixel to a definite land-cover class. Traditionally, subpixel mapping is based on the assumption of spatial dependence, and the spatial correlation information among pixels and subpixels is considered in the prediction of the spatial locations of land-cover classes within the mixed pixels. In this paper, a novel subpixel mapping method for hyperspectral remote sensing imagery based on a nonlocal method, namely nonlocal total variation subpixel mapping (NLTVSM, is proposed to use the nonlocal self-similarity prior to improve the performance of the subpixel mapping task. Differing from the existing spatial regularization subpixel mapping technique, in NLTVSM, the nonlocal total variation is used as a spatial regularizer to exploit the similar patterns and structures in the image. In this way, the proposed method can obtain an optimal subpixel mapping result and accuracy by considering the nonlocal spatial information. Compared with the classical and state-of-the-art subpixel mapping approaches, the experimental results using a simulated hyperspectral image, two synthetic hyperspectral remote sensing images, and a real hyperspectral image confirm that the proposed algorithm can obtain better results in both visual and quantitative evaluations.

  10. Comparative study of numerical schemes of TVD3, UNO3-ACM and optimized compact scheme

    Science.gov (United States)

    Lee, Duck-Joo; Hwang, Chang-Jeon; Ko, Duck-Kon; Kim, Jae-Wook

    1995-01-01

    Three different schemes are employed to solve the benchmark problem. The first one is a conventional TVD-MUSCL (Monotone Upwind Schemes for Conservation Laws) scheme. The second scheme is a UNO3-ACM (Uniformly Non-Oscillatory Artificial Compression Method) scheme. The third scheme is an optimized compact finite difference scheme modified by us: the 4th order Runge Kutta time stepping, the 4th order pentadiagonal compact spatial discretization with the maximum resolution characteristics. The problems of category 1 are solved by using the second (UNO3-ACM) and third (Optimized Compact) schemes. The problems of category 2 are solved by using the first (TVD3) and second (UNO3-ACM) schemes. The problem of category 5 is solved by using the first (TVD3) scheme. It can be concluded from the present calculations that the Optimized Compact scheme and the UN03-ACM show good resolutions for category 1 and category 2 respectively.

  11. Glycemic Variation in Tumor Patients with Total Parenteral Nutrition

    Directory of Open Access Journals (Sweden)

    Jin-Cheng Yang

    2015-01-01

    Full Text Available Background: Hyperglycemia is associated with poor clinical outcomes and mortality in several patients. However, studies evaluating hyperglycemia variation in tumor patients receiving total parenteral nutrition (TPN are scarce. The aim of this study was to assess the relationship between glycemia and tumor kinds with TPN by monitoring glycemic variation in tumor patients. Methods: This retrospective clinical trial selected 312 patients with various cancer types, whose unique nutrition treatment was TPN during the monitoring period. All patients had blood glucose (BG values assessed at least six times daily during the TPN infusion. The glycemic variation before and after TPN was set as the indicator to evaluate the factors influencing BG. Results: The clinical trial lasted 7.5 ± 3.0 days adjusted for age, gender, family cancer history and blood types. There were six cancer types: Hepatic carcinoma (HC, 21.8%, rectal carcinoma (17.3%, colon carcinoma (CC, 14.7%, gastric carcinoma (29.8%, pancreatic carcinoma (11.5%, and duodenal carcinoma (DC, 4.8%. The patients were divided into diabetes and nondiabetes groups. No statistical differences in TPN glucose content between diabetes and nondiabetes groups were found; however, the tumor types affected by BG values were obvious. With increasing BG values, DC, HC and CC were more represented than other tumor types in this sequence in diabetic individuals, as well as in the nondiabetic group. BG was inclined to be more easily influenced in the nondiabetes group. Other factors did not impact BG values, including gender, body mass index, and TPN infusion duration time. Conclusions: When tumor patients are treated with TPN, BG levels should be monitored according to different types of tumors, besides differentiating diabetes or nondiabetes patients. Special BG control is needed for DC, HC and CC in both diabetic and nondiabetic patients. If BG overtly increases, positive measurements are needed to control BG

  12. High resolution image reconstruction with constrained, total-variation minimization

    CERN Document Server

    Sidky, Emil Y; Duchin, Yuval; Ullberg, Christer; Pan, Xiaochuan

    2011-01-01

    This work is concerned with applying iterative image reconstruction, based on constrained total-variation minimization, to low-intensity X-ray CT systems that have a high sampling rate. Such systems pose a challenge for iterative image reconstruction, because a very fine image grid is needed to realize the resolution inherent in such scanners. These image arrays lead to under-determined imaging models whose inversion is unstable and can result in undesirable artifacts and noise patterns. There are many possibilities to stabilize the imaging model, and this work proposes a method which may have an advantage in terms of algorithm efficiency. The proposed method introduces additional constraints in the optimization problem; these constraints set to zero high spatial frequency components which are beyond the sensing capability of the detector. The method is demonstrated with an actual CT data set and compared with another method based on projection up-sampling.

  13. Rudin-Osher-Fatemi Total Variation Denoising using Split Bregman

    Directory of Open Access Journals (Sweden)

    Pascal Getreuer

    2012-05-01

    Full Text Available Denoising is the problem of removing noise from an image. The most commonly studied case is with additive white Gaussian noise (AWGN, where the observed noisy image f is related to the underlying true image u by f=u+η and η is at each point in space independently and identically distributed as a zero-mean Gaussian random variable. Total variation (TV regularization is a technique that was originally developed for AWGN image denoising by Rudin, Osher, and Fatemi. The TV regularization technique has since been applied to a multitude of other imaging problems, see for example Chan and Shen's book. We focus here on the split Bregman algorithm of Goldstein and Osher for TV-regularized denoising.

  14. Breast ultrasound tomography with total-variation regularization

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Lianjie [Los Alamos National Laboratory; Li, Cuiping [KARMANOS CANCER INSTIT.; Duric, Neb [KARMANOS CANCER INSTIT

    2009-01-01

    Breast ultrasound tomography is a rapidly developing imaging modality that has the potential to impact breast cancer screening and diagnosis. A new ultrasound breast imaging device (CURE) with a ring array of transducers has been designed and built at Karmanos Cancer Institute, which acquires both reflection and transmission ultrasound signals. To extract the sound-speed information from the breast data acquired by CURE, we have developed an iterative sound-speed image reconstruction algorithm for breast ultrasound transmission tomography based on total-variation (TV) minimization. We investigate applicability of the TV tomography algorithm using in vivo ultrasound breast data from 61 patients, and compare the results with those obtained using the Tikhonov regularization method. We demonstrate that, compared to the Tikhonov regularization scheme, the TV regularization method significantly improves image quality, resulting in sound-speed tomography images with sharp (preserved) edges of abnormalities and few artifacts.

  15. Iterative total variation schemes for nonlinear inverse problems

    Science.gov (United States)

    Bachmayr, Markus; Burger, Martin

    2009-10-01

    In this paper we discuss the construction, analysis and implementation of iterative schemes for the solution of inverse problems based on total variation regularization. Via different approximations of the nonlinearity we derive three different schemes resembling three well-known methods for nonlinear inverse problems in Hilbert spaces, namely iterated Tikhonov, Levenberg-Marquardt and Landweber. These methods can be set up such that all arising subproblems are convex optimization problems, analogous to those appearing in image denoising or deblurring. We provide a detailed convergence analysis and appropriate stopping rules in the presence of data noise. Moreover, we discuss the implementation of the schemes and the application to distributed parameter estimation in elliptic partial differential equations.

  16. Subspace Correction Methods for Total Variation and $\\ell_1$-Minimization

    KAUST Repository

    Fornasier, Massimo

    2009-01-01

    This paper is concerned with the numerical minimization of energy functionals in Hilbert spaces involving convex constraints coinciding with a seminorm for a subspace. The optimization is realized by alternating minimizations of the functional on a sequence of orthogonal subspaces. On each subspace an iterative proximity-map algorithm is implemented via oblique thresholding, which is the main new tool introduced in this work. We provide convergence conditions for the algorithm in order to compute minimizers of the target energy. Analogous results are derived for a parallel variant of the algorithm. Applications are presented in domain decomposition methods for degenerate elliptic PDEs arising in total variation minimization and in accelerated sparse recovery algorithms based on 1-minimization. We include numerical examples which show e.cient solutions to classical problems in signal and image processing. © 2009 Society for Industrial and Applied Physics.

  17. Fast Second Degree Total Variation Method for Image Compressive Sensing.

    Science.gov (United States)

    Liu, Pengfei; Xiao, Liang; Zhang, Jun

    2015-01-01

    This paper presents a computationally efficient algorithm for image compressive sensing reconstruction using a second degree total variation (HDTV2) regularization. Firstly, a preferably equivalent formulation of the HDTV2 functional is derived, which can be formulated as a weighted L1-L2 mixed norm of second degree image derivatives under the spectral decomposition framework. Secondly, using the equivalent formulation of HDTV2, we introduce an efficient forward-backward splitting (FBS) scheme to solve the HDTV2-based image reconstruction model. Furthermore, from the averaged non-expansive operator point of view, we make a detailed analysis on the convergence of the proposed FBS algorithm. Experiments on medical images demonstrate that the proposed method outperforms several fast algorithms of the TV and HDTV2 reconstruction models in terms of peak signal to noise ratio (PSNR), structural similarity index (SSIM) and convergence speed.

  18. Total-variation-based methods for gravitational wave denoising

    CERN Document Server

    Torres, Alejandro; Font, José A; Ibáñez, José M

    2014-01-01

    We describe new methods for denoising and detection of gravitational waves embedded in additive Gaussian noise. The methods are based on Total Variation denoising algorithms. These algorithms, which do not need any a priori information about the signals, have been originally developed and fully tested in the context of image processing. To illustrate the capabilities of our methods we apply them to two different types of numerically-simulated gravitational wave signals, namely bursts produced from the core collapse of rotating stars and waveforms from binary black hole mergers. We explore the parameter space of the methods to find the set of values best suited for denoising gravitational wave signals under different conditions such as waveform type and signal-to-noise ratio. Our results show that noise from gravitational wave signals can be successfully removed with our techniques, irrespective of the signal morphology or astrophysical origin. We also combine our methods with spectrograms and show how those c...

  19. Total Variation Denoising and Support Localization of the Gradient

    Science.gov (United States)

    Chambolle, A.; Duval, V.; Peyré, G.; Poon, C.

    2016-10-01

    This paper describes the geometrical properties of the solutions to the total variation denoising method. A folklore statement is that this method is able to restore sharp edges, but at the same time, might introduce some staircasing (i.e. “fake” edges) in flat areas. Quite surprisingly, put aside numerical evidences, almost no theoretical result are available to backup these claims. The first contribution of this paper is a precise mathematical definition of the “extended support” (associated to the noise-free image) of TV denoising. This is intuitively the region which is unstable and will suffer from the staircasing effect. Our main result shows that the TV denoising method indeed restores a piece-wise constant image outside a small tube surrounding the extended support. Furthermore, the radius of this tube shrinks toward zero as the noise level vanishes and in some cases, an upper bound on the convergence rate is given.

  20. Image reconstruction from incomplete convolution data via total variation regularization

    Directory of Open Access Journals (Sweden)

    Zhida Shen

    2015-02-01

    Full Text Available Variational models with Total Variation (TV regularization have long been known to preserve image edges and produce high quality reconstruction. On the other hand, recent theory on compressive sensing has shown that it is feasible to accurately reconstruct  images from a few linear measurements via TV regularization. However, in general TV models are difficult to solve due to the nondifferentiability and the universal coupling of variables. In this paper, we propose the use of alternating direction method for image reconstruction from highly incomplete convolution data, where an image is reconstructed as a minimizer of an energy function that sums   a TV term for image regularity and a least squares term for data fitting. Our algorithm, called RecPK, takes advantage of problem structures and has an extremely low per-iteration cost. To demonstrate the efficiency of RecPK, we  compare it with TwIST, a state-of-the-art algorithm for minimizing TV models. Moreover, we also demonstrate the usefulness of RecPK in image zooming.

  1. Glycemic Variation in Tumor Patients with Total Parenteral Nutrition

    Institute of Scientific and Technical Information of China (English)

    Jin-Cheng Yang; Yuan-Yuan Dai; Li-Ming Wang; Yi-Bin Xie; Hai-Yan Zhou; Guo-Hui Li

    2015-01-01

    Background:Hyperglycemia is associated with poor clinical outcomes and mortality in several patients.However,studies evaluating hyperglycemia variation in tumor patients receiving total parenteral nutrition (TPN) are scarce.The aim of this study was to assess the relationship between glycemia and tumor kinds with TPN by monitoring glycemic variation in tumor patients.Methods:This retrospective clinical trial selected 312 patients with various cancer types,whose unique nutrition treatment was TPN during the monitoring period.All patients had blood glucose (BG) values assessed at least six times daily during the TPN infusion.The glycemic variation before and after TPN was set as the indicator to evaluate the factors influencing BG.Results:The clinical trial lasted 7.5 ± 3.0 days adjusted for age,gender,family cancer history and blood types.There were six cancer types:Hepatic carcinoma (HC,21.8%),rectal carcinoma (17.3%),colon carcinoma (CC,14.7%),gastric carcinoma (29.8%),pancreatic carcinoma (11.5%),and duodenal carcinoma (DC,4.8%).The patients were divided into diabetes and nondiabetes groups.No statistical differences in TPN glucose content between diabetes and nondiabetes groups were found;however,the tumor types affected by BG values were obvious.With increasing BG values,DC,HC and CC were more represented than other tumor types in this sequence in diabetic individuals,as well as in the nondiabetic group.BG was inclined to be more easily influenced in the nondiabetes group.Other factors did not impact BG values,includiug gender,body mass index,and TPN infusion duration time.Conclusions:When tumor patients are treated with TPN,BG levels should be monitored according to different types of tumors,besides differentiating diabetes or nondiabetes patients.Special BG control is needed for DC,HC and CC in both diabetic and nondiabetic patients.If BG overtly increases,positive measurements are needed to control BG values.The ClinicalTrials.gov ID is NCT

  2. Biological variation of total prostate-specific antigen

    DEFF Research Database (Denmark)

    Söletormos, Georg; Semjonow, Axel; Sibley, Paul E C

    2005-01-01

    , and estimates for the biological variation of tPSA could be derived from 12 of these studies. RESULTS: The mean biological variation was 20% in the concentration range 0.1-20 microg/L for men over 50 years. The biological variation means that the one-sided 95% confidence interval (CI) of the dispersion...

  3. An Iterative Shrinkage Approach to Total-Variation Image Restoration

    CERN Document Server

    Michailovich, Oleg

    2009-01-01

    The problem of restoration of digital images from their degraded measurements plays a central role in a multitude of practically important applications. A particularly challenging instance of this problem occurs in the case when the degradation phenomenon is modeled by an ill-conditioned operator. In such a case, the presence of noise makes it impossible to recover a valuable approximation of the image of interest without using some a priori information about its properties. Such a priori information is essential for image restoration, rendering it stable and robust to noise. Particularly, if the original image is known to be a piecewise smooth function, one of the standard priors used in this case is defined by the Rudin-Osher-Fatemi model, which results in total variation (TV) based image restoration. The current arsenal of algorithms for TV-based image restoration is vast. In the present paper, a different approach to the solution of the problem is proposed based on the method of iterative shrinkage (aka i...

  4. Electron tomography based on a total variation minimization reconstruction technique

    Energy Technology Data Exchange (ETDEWEB)

    Goris, B., E-mail: bart.goris@ua.ac.be [EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Van den Broek, W. [EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Batenburg, K.J. [Centrum Wiskunde and Informatica, Science Park 123, NL-1098XG Amsterdam (Netherlands); Vision Lab, University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk (Belgium); Heidari Mezerji, H.; Bals, S. [EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium)

    2012-02-15

    The 3D reconstruction of a tilt series for electron tomography is mostly carried out using the weighted backprojection (WBP) algorithm or using one of the iterative algorithms such as the simultaneous iterative reconstruction technique (SIRT). However, it is known that these reconstruction algorithms cannot compensate for the missing wedge. Here, we apply a new reconstruction algorithm for electron tomography, which is based on compressive sensing. This is a field in image processing specialized in finding a sparse solution or a solution with a sparse gradient to a set of ill-posed linear equations. Therefore, it can be applied to electron tomography where the reconstructed objects often have a sparse gradient at the nanoscale. Using a combination of different simulated and experimental datasets, it is shown that missing wedge artefacts are reduced in the final reconstruction. Moreover, it seems that the reconstructed datasets have a higher fidelity and are easier to segment in comparison to reconstructions obtained by more conventional iterative algorithms. -- Highlights: Black-Right-Pointing-Pointer A reconstruction algorithm for electron tomography is investigated based on total variation minimization. Black-Right-Pointing-Pointer Missing wedge artefacts are reduced by this algorithm. Black-Right-Pointing-Pointer The reconstruction is easier to segment. Black-Right-Pointing-Pointer More reliable quantitative information can be obtained.

  5. A Fast Wavelet Multilevel Approach to Total Variation Image Denoising

    Directory of Open Access Journals (Sweden)

    Kossi Edoh

    2009-09-01

    Full Text Available In this paper we present an adaptive multilevel total variational (TV method for image denoising which utilizes TV partial differential equation (PDE models and exploits the multiresolution properties of wavelets. The adaptive multilevel TV method provides fast adaptive wavelet-based solvers for the TV model. Our approach employs a wavelet collocation method applied to the TV model using two-dimensional anisotropic tensor product of Daubechies wavelets. The algorithm inherently combines the denoising property of wavelet compression algorithms with that of the TV model, and produces results superior to each method when implemented alone. It exploits the edge preservation property of the TVmodel to reduce the oscillations that may be generated around the edges in wavelet compression. In contrast with previous work combining TV denoising with wavelet compression, the method presented in this paper treats the numerical solution in a novel waywhich decreases the computational cost associated with the solution of the TV model. We present a detailed description of our method and results which indicate that a combination of wavelet based denoising techniques with the TV model produces superior results, for afraction of the computational cost.

  6. A Total Variation-Based Reconstruction Method for Dynamic MRI

    Directory of Open Access Journals (Sweden)

    Germana Landi

    2008-01-01

    Full Text Available In recent years, total variation (TV regularization has become a popular and powerful tool for image restoration and enhancement. In this work, we apply TV minimization to improve the quality of dynamic magnetic resonance images. Dynamic magnetic resonance imaging is an increasingly popular clinical technique used to monitor spatio-temporal changes in tissue structure. Fast data acquisition is necessary in order to capture the dynamic process. Most commonly, the requirement of high temporal resolution is fulfilled by sacrificing spatial resolution. Therefore, the numerical methods have to address the issue of images reconstruction from limited Fourier data. One of the most successful techniques for dynamic imaging applications is the reduced-encoded imaging by generalized-series reconstruction method of Liang and Lauterbur. However, even if this method utilizes a priori data for optimal image reconstruction, the produced dynamic images are degraded by truncation artifacts, most notably Gibbs ringing, due to the spatial low resolution of the data. We use a TV regularization strategy in order to reduce these truncation artifacts in the dynamic images. The resulting TV minimization problem is solved by the fixed point iteration method of Vogel and Oman. The results of test problems with simulated and real data are presented to illustrate the effectiveness of the proposed approach in reducing the truncation artifacts of the reconstructed images.

  7. Novel crystal timing calibration method based on total variation

    Science.gov (United States)

    Yu, Xingjian; Isobe, Takashi; Watanabe, Mitsuo; Liu, Huafeng

    2016-11-01

    A novel crystal timing calibration method based on total variation (TV), abbreviated as ‘TV merge’, has been developed for a high-resolution positron emission tomography (PET) system. The proposed method was developed for a system with a large number of crystals, it can provide timing calibration at the crystal level. In the proposed method, the timing calibration process was formulated as a linear problem. To robustly optimize the timing resolution, a TV constraint was added to the linear equation. Moreover, to solve the computer memory problem associated with the calculation of the timing calibration factors for systems with a large number of crystals, the merge component was used for obtaining the crystal level timing calibration values. Compared with other conventional methods, the data measured from a standard cylindrical phantom filled with a radioisotope solution was sufficient for performing a high-precision crystal-level timing calibration. In this paper, both simulation and experimental studies were performed to demonstrate the effectiveness and robustness of the TV merge method. We compare the timing resolutions of a 22Na point source, which was located in the field of view (FOV) of the brain PET system, with various calibration techniques. After implementing the TV merge method, the timing resolution improved from 3.34 ns at full width at half maximum (FWHM) to 2.31 ns FWHM.

  8. Infimal convolution of total generalized variation functionals for dynamic MRI.

    Science.gov (United States)

    Schloegl, Matthias; Holler, Martin; Schwarzl, Andreas; Bredies, Kristian; Stollberger, Rudolf

    2017-07-01

    To accelerate dynamic MR applications using infimal convolution of total generalized variation functionals (ICTGV) as spatio-temporal regularization for image reconstruction. ICTGV comprises a new image prior tailored to dynamic data that achieves regularization via optimal local balancing between spatial and temporal regularity. Here it is applied for the first time to the reconstruction of dynamic MRI data. CINE and perfusion scans were investigated to study the influence of time dependent morphology and temporal contrast changes. ICTGV regularized reconstruction from subsampled MR data is formulated as a convex optimization problem. Global solutions are obtained by employing a duality based non-smooth optimization algorithm. The reconstruction error remains on a low level with acceleration factors up to 16 for both CINE and dynamic contrast-enhanced MRI data. The GPU implementation of the algorithm suites clinical demands by reducing reconstruction times of one dataset to less than 4 min. ICTGV based dynamic magnetic resonance imaging reconstruction allows for vast undersampling and therefore enables for very high spatial and temporal resolutions, spatial coverage and reduced scan time. With the proposed distinction of model and regularization parameters it offers a new and robust method of flexible decomposition into components with different degrees of temporal regularity. Magn Reson Med 78:142-155, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  9. Total Variation Based Perceptual Image Quality Assessment Modeling

    Directory of Open Access Journals (Sweden)

    Yadong Wu

    2014-01-01

    Full Text Available Visual quality measure is one of the fundamental and important issues to numerous applications of image and video processing. In this paper, based on the assumption that human visual system is sensitive to image structures (edges and image local luminance (light stimulation, we propose a new perceptual image quality assessment (PIQA measure based on total variation (TV model (TVPIQA in spatial domain. The proposed measure compares TVs between a distorted image and its reference image to represent the loss of image structural information. Because of the good performance of TV model in describing edges, the proposed TVPIQA measure can illustrate image structure information very well. In addition, the energy of enclosed regions in a difference image between the reference image and its distorted image is used to measure the missing luminance information which is sensitive to human visual system. Finally, we validate the performance of TVPIQA measure with Cornell-A57, IVC, TID2008, and CSIQ databases and show that TVPIQA measure outperforms recent state-of-the-art image quality assessment measures.

  10. Computerized tomography with total variation and with shearlets

    Science.gov (United States)

    Garduño, Edgar; Herman, Gabor T.

    2017-04-01

    To reduce the x-ray dose in computerized tomography (CT), many constrained optimization approaches have been proposed aiming at minimizing a regularizing function that measures a lack of consistency with some prior knowledge about the object that is being imaged, subject to a (predetermined) level of consistency with the detected attenuation of x-rays. One commonly investigated regularizing function is total variation (TV), while other publications advocate the use of some type of multiscale geometric transform in the definition of the regularizing function, a particular recent choice for this is the shearlet transform. Proponents of the shearlet transform in the regularizing function claim that the reconstructions so obtained are better than those produced using TV for texture preservation (but may be worse for noise reduction). In this paper we report results related to this claim. In our reported experiments using simulated CT data collection of the head, reconstructions whose shearlet transform has a small ℓ 1-norm are not more efficacious than reconstructions that have a small TV value. Our experiments for making such comparisons use the recently-developed superiorization methodology for both regularizing functions. Superiorization is an automated procedure for turning an iterative algorithm for producing images that satisfy a primary criterion (such as consistency with the observed measurements) into its superiorized version that will produce results that, according to the primary criterion are as good as those produced by the original algorithm, but in addition are superior to them according to a secondary (regularizing) criterion. The method presented for superiorization involving the ℓ 1-norm of the shearlet transform is novel and is quite general: It can be used for any regularizing function that is defined as the ℓ 1-norm of a transform specified by the application of a matrix. Because in the previous literature the split Bregman algorithm is used

  11. Discontinuous Galerkin Method for Total Variation Minimization on one-dimensional Inpainting Problem

    CERN Document Server

    Wang, Xijian

    2011-01-01

    This paper is concerned with the numerical minimization of energy functionals in $BV(\\Omega)$ (the space of bounded variation functions) involving total variation for gray-scale 1-dimensional inpainting problem. Applications are shown by finite element method and discontinuous Galerkin method for total variation minimization. We include the numerical examples which show the different recovery image by these two methods.

  12. Total Electron Content Lunar Variation at Two Midlatitude Stations.

    Science.gov (United States)

    1980-10-30

    the critical frequency, the virtual height or the height of the maximum of the layer. lNo- re recently, Huang (1978) made an analysis of the total...at libro has a zero value in the afternodnbet ween 15hr and 16hr local solar time, Besides the zero of the 8hr-10hr local solar time.The pha se in

  13. Continuum limit of total variation on point clouds

    OpenAIRE

    Trillos, Nicolás García; Slepčev, Dejan

    2014-01-01

    We consider point clouds obtained as random samples of a measure on a Euclidean domain. A graph representing the point cloud is obtained by assigning weights to edges based on the distance between the points they connect. Our goal is to develop mathematical tools needed to study the consistency, as the number of available data points increases, of graph-based machine learning algorithms for tasks such as clustering. In particular, we study when is the cut capacity, and more generally total va...

  14. HARDI DATA DENOISING USING VECTORIAL TOTAL VARIATION AND LOGARITHMIC BARRIER

    Science.gov (United States)

    Kim, Yunho; Thompson, Paul M.; Vese, Luminita A.

    2010-01-01

    In this work, we wish to denoise HARDI (High Angular Resolution Diffusion Imaging) data arising in medical brain imaging. Diffusion imaging is a relatively new and powerful method to measure the three-dimensional profile of water diffusion at each point in the brain. These images can be used to reconstruct fiber directions and pathways in the living brain, providing detailed maps of fiber integrity and connectivity. HARDI data is a powerful new extension of diffusion imaging, which goes beyond the diffusion tensor imaging (DTI) model: mathematically, intensity data is given at every voxel and at any direction on the sphere. Unfortunately, HARDI data is usually highly contaminated with noise, depending on the b-value which is a tuning parameter pre-selected to collect the data. Larger b-values help to collect more accurate information in terms of measuring diffusivity, but more noise is generated by many factors as well. So large b-values are preferred, if we can satisfactorily reduce the noise without losing the data structure. Here we propose two variational methods to denoise HARDI data. The first one directly denoises the collected data S, while the second one denoises the so-called sADC (spherical Apparent Diffusion Coefficient), a field of radial functions derived from the data. These two quantities are related by an equation of the form S = SSexp (−b · sADC) (in the noise-free case). By applying these two different models, we will be able to determine which quantity will most accurately preserve data structure after denoising. The theoretical analysis of the proposed models is presented, together with experimental results and comparisons for denoising synthetic and real HARDI data. PMID:20802839

  15. Combined First and Second Order Total Variation Inpainting using Split Bregman

    Directory of Open Access Journals (Sweden)

    Konstantinos Papafitsoros

    2013-07-01

    Full Text Available In this article we discuss the implementation of the combined first and second order total variation inpainting that was introduced by Papafitsoros and Schdönlieb. We describe the algorithm we use (split Bregman in detail, and we give some examples that indicate the difference between pure first and pure second order total variation inpainting.

  16. Combined First and Second Order Total Variation Inpainting using Split Bregman

    KAUST Repository

    Papafitsoros, Konstantinos

    2013-07-12

    In this article we discuss the implementation of the combined first and second order total variation inpainting that was introduced by Papafitsoros and Schdönlieb. We describe the algorithm we use (split Bregman) in detail, and we give some examples that indicate the difference between pure first and pure second order total variation inpainting.

  17. Split Bregman Iteration Algorithm for Image Deblurring Using Fourth-Order Total Bounded Variation Regularization Model

    Directory of Open Access Journals (Sweden)

    Yi Xu

    2013-01-01

    Full Text Available We propose a fourth-order total bounded variation regularization model which could reduce undesirable effects effectively. Based on this model, we introduce an improved split Bregman iteration algorithm to obtain the optimum solution. The convergence property of our algorithm is provided. Numerical experiments show the more excellent visual quality of the proposed model compared with the second-order total bounded variation model which is proposed by Liu and Huang (2010.

  18. Assessment of vectorial total variation penalties on realistic dual-energy CT data.

    Science.gov (United States)

    Rigie, David S; Sanchez, Adrian A; La Rivière, Patrick J

    2017-04-21

    Vectorial extensions of total variation have recently been developed for regularizing the reconstruction and denoising of multi-channel images, such as those arising in spectral computed tomography. Early studies have focused mainly on simulated, piecewise-constant images whose structure may favor total-variation penalties. In the current manuscript, we apply vectorial total variation to real dual-energy CT data of a whole turkey in order to determine if the same benefits can be observed in more complex images with anatomically realistic textures. We consider the total nuclear variation ([Formula: see text]) as well as another vectorial total variation based on the Frobenius norm ([Formula: see text]) and standard channel-by-channel total variation ([Formula: see text]). We performed a series of 3D TV denoising experiments comparing the three TV variants across a wide range of smoothness parameter settings, optimizing each regularizer according to a very-high-dose 'ground truth' image. Consistent with the simulation studies, we find that both vectorial TV variants achieve a lower error than the channel-by-channel TV and are better able to suppress noise while preserving actual image features. In this real data study, the advantages are subtler than in the previous simulation study, although the [Formula: see text] penalty is found to have clear advantages over either [Formula: see text] or [Formula: see text] when comparing material images formed from linear combinations of the denoised energy images.

  19. Total variation regularization in measurement and image space for PET reconstruction

    KAUST Repository

    Burger, M

    2014-09-18

    © 2014 IOP Publishing Ltd. The aim of this paper is to test and analyse a novel technique for image reconstruction in positron emission tomography, which is based on (total variation) regularization on both the image space and the projection space. We formulate our variational problem considering both total variation penalty terms on the image and on an idealized sinogram to be reconstructed from a given Poisson distributed noisy sinogram. We prove existence, uniqueness and stability results for the proposed model and provide some analytical insight into the structures favoured by joint regularization. For the numerical solution of the corresponding discretized problem we employ the split Bregman algorithm and extensively test the approach in comparison to standard total variation regularization on the image. The numerical results show that an additional penalty on the sinogram performs better on reconstructing images with thin structures.

  20. Approximate Sparsity and Nonlocal Total Variation Based Compressive MR Image Reconstruction

    Directory of Open Access Journals (Sweden)

    Chengzhi Deng

    2014-01-01

    Full Text Available Recent developments in compressive sensing (CS show that it is possible to accurately reconstruct the magnetic resonance (MR image from undersampled k-space data by solving nonsmooth convex optimization problems, which therefore significantly reduce the scanning time. In this paper, we propose a new MR image reconstruction method based on a compound regularization model associated with the nonlocal total variation (NLTV and the wavelet approximate sparsity. Nonlocal total variation can restore periodic textures and local geometric information better than total variation. The wavelet approximate sparsity achieves more accurate sparse reconstruction than fixed wavelet l0 and l1 norm. Furthermore, a variable splitting and augmented Lagrangian algorithm is presented to solve the proposed minimization problem. Experimental results on MR image reconstruction demonstrate that the proposed method outperforms many existing MR image reconstruction methods both in quantitative and in visual quality assessment.

  1. A Different View of Solar Spectral Irradiance Variations: Modeling Total Energy over Six-Month Intervals.

    Science.gov (United States)

    Woods, Thomas N; Snow, Martin; Harder, Jerald; Chapman, Gary; Cookson, Angela

    A different approach to studying solar spectral irradiance (SSI) variations, without the need for long-term (multi-year) instrument degradation corrections, is examining the total energy of the irradiance variation during 6-month periods. This duration is selected because a solar active region typically appears suddenly and then takes 5 to 7 months to decay and disperse back into the quiet-Sun network. The solar outburst energy, which is defined as the irradiance integrated over the 6-month period and thus includes the energy from all phases of active region evolution, could be considered the primary cause for the irradiance variations. Because solar cycle variation is the consequence of multiple active region outbursts, understanding the energy spectral variation may provide a reasonable estimate of the variations for the 11-year solar activity cycle. The moderate-term (6-month) variations from the Solar Radiation and Climate Experiment (SORCE) instruments can be decomposed into positive (in-phase with solar cycle) and negative (out-of-phase) contributions by modeling the variations using the San Fernando Observatory (SFO) facular excess and sunspot deficit proxies, respectively. These excess and deficit variations are fit over 6-month intervals every 2 months over the mission, and these fitted variations are then integrated over time for the 6-month energy. The dominant component indicates which wavelengths are in-phase and which are out-of-phase with solar activity. The results from this study indicate out-of-phase variations for the 1400 - 1600 nm range, with all other wavelengths having in-phase variations.

  2. Quantitative bounds for Markov chain convergence: Wasserstein and total variation distances

    CERN Document Server

    Madras, Neal; 10.3150/09-BEJ238

    2011-01-01

    We present a framework for obtaining explicit bounds on the rate of convergence to equilibrium of a Markov chain on a general state space, with respect to both total variation and Wasserstein distances. For Wasserstein bounds, our main tool is Steinsaltz's convergence theorem for locally contractive random dynamical systems. We describe practical methods for finding Steinsaltz's "drift functions" that prove local contractivity. We then use the idea of "one-shot coupling" to derive criteria that give bounds for total variation distances in terms of Wasserstein distances. Our methods are applied to two examples: a two-component Gibbs sampler for the Normal distribution and a random logistic dynamical system.

  3. Calibration of the Volatility in Option Pricing Using the Total Variation Regularization

    Directory of Open Access Journals (Sweden)

    Yu-Hua Zeng

    2014-01-01

    Full Text Available In market transactions, volatility, which is a very important risk measurement in financial economics, has significantly intimate connection with the future risk of the underlying assets. Identifying the implied volatility is a typical PDE inverse problem. In this paper, based on the total variation regularization strategy, a bivariate total variation regularization model is proposed to estimate the implied volatility. We not only prove the existence of the solution, but also provide the necessary condition of the optimal control problem—Euler-Lagrange equation. The stability and convergence analyses for the proposed approach are also given. Finally, numerical experiments have been carried out to show the effectiveness of the method.

  4. A novel autofocus algorithm based on maximum total variation criteria for SAR images

    Institute of Scientific and Technical Information of China (English)

    MA Lun; LIAO Guisheng

    2007-01-01

    A novel autofocus algorithm for synthetic aperture radar (SAR)based on total variation is presented in this Paper.The method,which starts with a complex phase-degraded SAR image,after the phase errors model is introduced into the range-compressed phase-history domain,carries out phase errors correction by changing the focus till the total variation of the azimuth profile is maximized.Compared with the minimum entropy autofocus algorithm,the autofocus algorithm has less computational complexity and is easier to implement.The simulation and the processing results of the measured data show the validity of the proposed method.

  5. Research on Mechanical Fault Diagnosis Scheme Based on Improved Wavelet Total Variation Denoising

    Directory of Open Access Journals (Sweden)

    Wentao He

    2016-01-01

    Full Text Available Wavelet analysis is a powerful tool for signal processing and mechanical equipment fault diagnosis due to the advantages of multiresolution analysis and excellent local characteristics in time-frequency domain. Wavelet total variation (WATV was recently developed based on the traditional wavelet analysis method, which combines the advantages of wavelet-domain sparsity and total variation (TV regularization. In order to guarantee the sparsity and the convexity of the total objective function, nonconvex penalty function is chosen as a new wavelet penalty function in WATV. The actual noise reduction effect of WATV method largely depends on the estimation of the noise signal variance. In this paper, an improved wavelet total variation (IWATV denoising method was introduced. The local variance analysis on wavelet coefficients obtained from the wavelet decomposition of noisy signals is employed to estimate the noise variance so as to provide a scientific evaluation index. Through the analysis of the numerical simulation signal and real-word failure data, the results demonstrated that the IWATV method has obvious advantages over the traditional wavelet threshold denoising and total variation denoising method in the mechanical fault diagnose.

  6. Variation in age and physical status prior to total knee and hip replacement surgery

    DEFF Research Database (Denmark)

    Ackerman, Ilana N; Dieppe, Paul A; March, Lyn M

    2009-01-01

    OBJECTIVE: To investigate whether variation exists in the preoperative age, pain, stiffness, and physical function of people undergoing total knee replacement (TKR) and total hip replacement (THR) at several centers in Australia and Europe. METHODS: Individual Western Ontario and Mc...... in the timing of joint replacement across the centers studied, with potential for compromised surgical outcomes due to premature or delayed surgery. Possible contributing factors include patient preferences, the absence of concrete indications for surgery, and the capacity of the health care systems....

  7. A Total Variation Model Based on the Strictly Convex Modification for Image Denoising

    Directory of Open Access Journals (Sweden)

    Boying Wu

    2014-01-01

    Full Text Available We propose a strictly convex functional in which the regular term consists of the total variation term and an adaptive logarithm based convex modification term. We prove the existence and uniqueness of the minimizer for the proposed variational problem. The existence, uniqueness, and long-time behavior of the solution of the associated evolution system is also established. Finally, we present experimental results to illustrate the effectiveness of the model in noise reduction, and a comparison is made in relation to the more classical methods of the traditional total variation (TV, the Perona-Malik (PM, and the more recent D-α-PM method. Additional distinction from the other methods is that the parameters, for manual manipulation, in the proposed algorithm are reduced to basically only one.

  8. Opinions among Danish knee surgeons about indications to perform total knee replacement showed considerable variation

    DEFF Research Database (Denmark)

    Troelsen, Anders; Schrøder, Henrik; Husted, Henrik

    2012-01-01

    During the past decade, the incidence of primary total knee replacement (TKA) surgery in Denmark has approximately doubled. This increase could be due to weakened indications to perform TKA surgery. We aimed to investigate variation in opinions about indications to perform TKA among Danish knee...

  9. Attenuation correction for the HRRT PET-scanner using transmission scatter correction and total variation regularization

    DEFF Research Database (Denmark)

    Keller, Sune H; Svarer, Claus; Sibomana, Merence

    2013-01-01

    scatter correction in the μ-map reconstruction and total variation filtering to the transmission processing. Results: Comparing MAP-TR and the new TXTV with gold standard CT-based attenuation correction, we found that TXTV has less bias as compared to MAP-TR. We also compared images acquired at the HRRT...

  10. Algorithms and software for total variation image reconstruction via first-order methods

    DEFF Research Database (Denmark)

    Dahl, Joahim; Hansen, Per Christian; Jensen, Søren Holdt

    2010-01-01

    This paper describes new algorithms and related software for total variation (TV) image reconstruction, more specifically: denoising, inpainting, and deblurring. The algorithms are based on one of Nesterov's first-order methods, tailored to the image processing applications in such a way that...

  11. Implementation of an optimal first-order method for strongly convex total variation regularization

    DEFF Research Database (Denmark)

    Jensen, Tobias Lindstrøm; Jørgensen, Jakob Heide; Hansen, Per Christian;

    2012-01-01

    We present a practical implementation of an optimal first-order method, due to Nesterov, for large-scale total variation regularization in tomographic reconstruction, image deblurring, etc. The algorithm applies to μ-strongly convex objective functions with L-Lipschitz continuous gradient...

  12. Total variation denoising of probability measures using iterated function systems with probabilities

    Science.gov (United States)

    La Torre, Davide; Mendivil, Franklin; Vrscay, Edward R.

    2017-01-01

    In this paper we present a total variation denoising problem for probability measures using the set of fixed point probability measures of iterated function systems with probabilities IFSP. By means of the Collage Theorem for contraction mappings, we provide an upper bound for this problem that can be solved by determining a set of probabilities.

  13. Total variation based edge enhancement for level set segmentation and asymmetry analysis in breast thermograms.

    Science.gov (United States)

    Prabha, S; Anandh, K R; Sujatha, C M; Ramakrishnan, S

    2014-01-01

    In this work, an attempt has been made to perform asymmetry analysis in breast thermograms using non-linear total variation diffusion filter and reaction diffusion based level set method. Breast images used in this study are obtained from online database of the project PROENG. Initially the images are subjected to total variation (TV) diffusion filter to generate the edge map. Reaction diffusion based level set method is employed to segment the breast tissues using TV edge map as stopping boundary function. Asymmetry analysis is performed on the segmented breast tissues using wavelet based structural texture features. The results show that nonlinear total variation based reaction diffusion level set method could efficiently segment the breast tissues. This method yields high correlation between the segmented output and the ground truth than the conventional level set. Structural texture features extracted from the wavelet coefficients are found to be significant in demarcating normal and abnormal tissues. Hence, it appears that the asymmetry analysis on segmented breast tissues extracted using total variation edge map can be used efficiently to identify the pathological conditions of breast thermograms.

  14. Front tracking in recirculating flows: a comparison between the TVD and RCM methods in solving the VOF equation

    Directory of Open Access Journals (Sweden)

    L. F. Lopes Silva

    2005-03-01

    Full Text Available The modeling and simulation of mold filling must include a method to capture the interface formed between the inlet fluid and the fluid that was initially in the mold. A commonly used front-capturing method in a Eulerian mesh is the volume-of-fluid (VOF method. The VOF advection equation solution may show numerical diffusion and/or dispersion and high-order numerical schemes, such as the TVD schemes with dimensional splitting, have to be employed to discretize the convective terms. The present contribution explores the use of RCM for solution of the VOF color-function equation during mold filling with recirculating flows. The Navier-Stokes equations are solved by a finite-volume method using the SIMPLER algorithm. Filling simulations using the TVD and RCM methods are compared. RCM was able to generate diffusion-free results, sharply defining the interface, even when topological changes (generation of droplets occur.

  15. Longitudinal and latitudinal variations of the total ozone over the Central Andes

    Energy Technology Data Exchange (ETDEWEB)

    Zaratti, F.; Andrade, M.; Forno, R.; Palenque, E.R. [La Paz, Univ. Mayor de San Andres (Bolivia). Ist. de Investigaciones Fisicas. Lab. de Ozono y Radiacion Ultravioleta

    1999-04-01

    From the Total Ozone Mapping Spectrometer (TOMS) data released by NASA, some analysis has been done in order to point out anomalies in the time and space distributions of the total ozone. Also some explanations for them have been tried. The paper focuses on the longitudinal and altitude anomalies in a region characterized by strong variations in orography, as are the Andes at low and mid latitude. As a result of the analysis, the authors conclude that there is a depletion of the total ozone over the 'Altipiano' and discuss some possible explanations of the phenomenon.

  16. Effect of March 9, 2016 Total Solar Eclipse on geomagnetic field variation

    Science.gov (United States)

    Ruhimat, Mamat; Winarko, Anton; Nuraeni, Fitri; Bangkit, Harry; Aris, M. Andi; Suwardi; Sulimin

    2016-11-01

    During solar eclipse, solar radiation to the Earth is blocked by the Moon. Thus, the ionization process in the ionosphere is disrupted, as well as the variation of geomagnetic field. The disturbance of geomagnetic field is caused by electric current in the E layer of the ionosphere. At low latitude, the current which is dominant in quiet day is the Sq currents. The blocking of solar radiation cause decrement in electron density in the blocked region. The aim of the research is to find the effect of total solar eclipse to the geomagnetic field. The measurement of the geomagnetic field variation during total solar eclipse on March 9, 2016 was carried out at the Meteorological station of BMKG in Ternate (0° 49' 45.20 "N; 127° 22' 54.00" E). By eliminating the geomagnetic disturbance that occurred in a daily geomagnetic field variation, the pattern of quiet day which is usually in a shape of smooth curve became affected. During the total solar eclipse on March 9, 2016 from 00:30 until 02:00 UT, we found that the geomagnetic field variation of the quiet day decreased by -5 nT.

  17. Evaluation of dose variation during total skin electron irradiation using thermoluminescent dosimeters

    Energy Technology Data Exchange (ETDEWEB)

    Weaver, R.D.; Gerbi, B.J.; Dusenbery, K.E. [Univ. of Minnesota Hospital, Minneaspolis, MN (United States)

    1995-09-30

    The purpose of this study was to determine acceptable dose variation using thermoluminescent dosimeters (TLD) in the treatment of Mycosis Fungoides with total skin electron beam (TSEB) irradiation. From 1983 to 1993, 22 patients were treated with total skin electron beam therapy in the standing position. A six-field technique was used to deliver 2 Gy in two days, treating 4 days per week, to a total dose of 35 to 40 Gy using a degraded 9 MeV electron beam. Thermoluminescent dosimeters were placed on several locations of the body and the results recorded. The variations in these readings were analyzed to determine normal dose variation for various body location during TSEB. The dose to flat surfaces of the body was essentially the same as the dose to the prescription point. The dose to tangential surfaces was within {plus_minus} 10% of the prescription dose, but the readings showed much more variation (up to 24%). Thin areas of the body showed large deviations from the prescription dose along with a large amount of variation in the readings (up to 22%). Special areas of the body, such as the perineum and eyelid, showed large deviations from the prescription dose along with very large (up to 40%) variations in the readings. The TLD results of this study will be used as a quality assurance check for all new patients treated with TSEB. The results of the TLDs will be compared with this baseline study to determine if the delivered dose is within acceptable ranges. If the TLD results fall outside the acceptable limits established above, then the patient position can be modified or the technique itself evaluated. 4 refs., 5 tabs.

  18. Total mean curvature, scalar curvature, and a variational analog of Brown-York mass

    CERN Document Server

    Mantoulidis, Christos

    2016-01-01

    Let $(\\Omega, g)$ be a compact Riemannian 3-manifold with nonnegative scalar curvature, and with a mean-convex boundary $\\Sigma$ which is topologically a 2-sphere. We demonstrate that the total mean curvature of $\\Sigma$ is bounded from above by a constant depending only on the induced metric on $\\Sigma$. As an application, we define a variational analog of the Brown-York quasi-local mass of $\\Sigma$ in $(\\Omega, g)$ without assuming that $\\Sigma$ has positive Gauss curvature. We also cast this discussion in the light of a natural variational problem on compact 3-manifolds with boundary and nonnegative scalar curvature.

  19. Total blood volume in the normally performing Standardbred trotter: age and sex variations.

    Science.gov (United States)

    Persson, S G; Funkquist, P; Nyman, G

    1996-03-01

    The purposes of this study were to elucidate the influences of age and sex on the mass specific blood volume parameters: total blood volume (TBV/BW, ml/kg), plasma volume (PV/ BW, ml/kg), total red cell volume (CV/BW, ml/kg) and maximal packed cell volume (PCV, l/l, i.e. after total mobilisation of the splenic red cell reservoir) and to establish reference values for these in normally performing Standardbred trotting race horses. In total 205 horses were studied. They were all, according to their owners and/or trainers, performing satisfactorily in racing or training for shortly impending racing. Blood volume determination was done with the Evans blue dye dilution technique after exercise induced emptying of the spleen. Both age and sex were found to influence variation of these parameters significantly, with the possible exception of PV/BW, whereas the primary variation appeared to be in CV/BW. It was concluded that taking age and sex dependent variations into consideration will render prediction of normal values for the blood volume parameters in the athletic Standardbred trotter more reliable and the detection of abnormal deviations more precise if five age and sex groups are used for comparisons.

  20. Joint Reconstruction of Multi-channel, Spectral CT Data via Constrained Total Nuclear Variation Minimization

    CERN Document Server

    Rigie, David

    2014-01-01

    We explore the use of the recently proposed "total nuclear variation" (TNV) \\cite{Rigie2014,Holt2014} as a regularizer for reconstructing multi-channel, spectral CT images. This convex penalty is a natural extension of the total variation (TV) to vector-valued images and has the advantage of encouraging common edge locations and a shared gradient direction among image channels. We show how it can be incorporated into a general, data-constrained reconstruction framework and derive update equations based on the first-order, primal-dual algorithm of Chambolle and Pock. Early simulation studies based on the numerical XCAT phantom indicate that the inter-channel coupling introduced by the TNV leads to better preservation of image features at high levels of regularization, compared to independent, channel-by-channel TV reconstructions.

  1. TV-SVM: Total Variation Support Vector Machine for Semi-Supervised Data Classification

    OpenAIRE

    Bresson, Xavier; Zhang, Ruiliang

    2012-01-01

    We introduce semi-supervised data classification algorithms based on total variation (TV), Reproducing Kernel Hilbert Space (RKHS), support vector machine (SVM), Cheeger cut, labeled and unlabeled data points. We design binary and multi-class semi-supervised classification algorithms. We compare the TV-based classification algorithms with the related Laplacian-based algorithms, and show that TV classification perform significantly better when the number of labeled data is small.

  2. A Weighted Difference of Anisotropic and Isotropic Total Variation Model for Image Processing

    Science.gov (United States)

    2014-09-01

    leads to the classical Potts model [32] or piece-wise constant Mumford-Shah model [28] for image segmentation or partition. Recently, Storath et. al...34] propose a hybrid ADMM and dynamic programming method to solve the Potts model . Motivated from L1 − L2 minimization of coherent CS [23, 41], we...A WEIGHTED DIFFERENCE OF ANISOTROPIC AND ISOTROPIC TOTAL VARIATION MODEL FOR IMAGE PROCESSING YIFEI LOU∗, TIEYONG ZENG† , STANLEY OSHER‡ , AND JACK

  3. A study of the one dimensional total generalised variation regularisation problem

    KAUST Repository

    Papafitsoros, Konstantinos

    2015-03-01

    © 2015 American Institute of Mathematical Sciences. In this paper we study the one dimensional second order total generalised variation regularisation (TGV) problem with L2 data fitting term. We examine the properties of this model and we calculate exact solutions using simple piecewise affine functions as data terms. We investigate how these solutions behave with respect to the TGV parameters and we verify our results using numerical experiments.

  4. Sensitivity-based model updating for structural damage identification using total variation regularization

    Science.gov (United States)

    Grip, Niklas; Sabourova, Natalia; Tu, Yongming

    2017-02-01

    Sensitivity-based Finite Element Model Updating (FEMU) is one of the widely accepted techniques used for damage identification in structures. FEMU can be formulated as a numerical optimization problem and solved iteratively making automatic updating of the unknown model parameters by minimizing the difference between measured and analytical structural properties. However, in the presence of noise in the measurements, the updating results are usually prone to errors. This is mathematically described as instability of the damage identification as an inverse problem. One way to resolve this problem is by using regularization. In this paper, we compare a well established interpolation-based regularization method against methods based on the minimization of the total variation of the unknown model parameters. These are new regularization methods for structural damage identification. We investigate how using Huber and pseudo Huber functions in the definition of total variation affects important properties of the methods. For instance, for well-localized damages the results show a clear advantage of the total variation based regularization in terms of the identified location and severity of damage compared with the interpolation-based solution. For a practical test of the proposed method we use a reinforced concrete plate. Measurements and analysis were performed first on an undamaged plate, and then repeated after applying four different degrees of damage.

  5. Office workers' objectively assessed total and prolonged sitting time: Individual-level correlates and worksite variations

    Directory of Open Access Journals (Sweden)

    Nyssa T. Hadgraft

    2016-12-01

    Full Text Available Sedentary behavior is highly prevalent in office-based workplaces; however, few studies have assessed the attributes associated with this health risk factor in the workplace setting. This study aimed to identify the correlates of office workers' objectively-assessed total and prolonged (≥30 min bouts workplace sitting time. Participants were 231 Australian office workers recruited from 14 sites of a single government employer in 2012–13. Potential socio-demographic, work-related, health-related and cognitive-social correlates were measured through a self-administered survey and anthropometric measurements. Associations with total and prolonged workplace sitting time (measured with the activPAL3 were tested using linear mixed models. Worksites varied significantly in total workplace sitting time (overall mean [SD]: 79% [10%] of work hours and prolonged workplace sitting time (42% [19%], after adjusting for socio-demographic and work-related characteristics. Organisational tenure of 3–5 years (compared to tenure >5 years was associated with more time spent in total and prolonged workplace sitting time, while having a BMI categorised as obese (compared to a healthy BMI was associated with less time spent in total and prolonged workplace sitting time. Significant variations in sitting time were observed across different worksites of the same employer and the variation remained after adjusting for individual-level factors. Only BMI and organisational tenure were identified as correlates of total and prolonged workplace sitting time. Additional studies are needed to confirm the present findings across diverse organisations and occupations.

  6. Beam hardening correction using iterative total variation (ITV)-based algorithm in CBCT reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Chang-Woo; Cha, Bo Kyung; Jeon, Sungchae; Huh, Young [Converged Medical Device Research Center, Advanced Medical Device Research Division, KERI, Gyeonggido 426-910 (Korea, Republic of)

    2015-07-01

    Recently, beam hardening reduction is required to produce high-quality reconstructions of X-ray cone-beam computed tomography (CBCT) system for medical applications. This paper introduces the iterative total variation (ITV) for filtered-backprojection suffering from the serious beam hardening problems. Feldkamp, Davis, and Kress (FDK) reconstruction algorithm for CBCT system is widely used reconstruction technique. FDK reconstruction algorithm could be realized by generating the weighted projection data, filtering the projection images, and back-projecting the filtered projection data into the volume. However, FDK algorithm suffers from the beam hardening artifacts by X-ray attenuation coefficients. Recently, total variation (TV) method for compressed sensing (CS) has been particularly useful in exploiting the prior knowledge of minimal variation in the X-ray attenuation characteristics across object or human body. But a practical implementation of this method still remains a challenge. The main problem is the iterative nature of solving the TV-based CS formulation, which generally requires multiple iterations of forward and backward projections of a large dataset in clinically or industrially feasible time frame. In this paper, we propose ITV method after FDK reconstruction for reducing the beam hardening artifacts. The beam hardening problems are reduced by the ITV method to promote sparsity inherent in the X-ray attenuation characteristics. (authors)

  7. Bayesian Image Restoration Using a Large-Scale Total Patch Variation Prior

    Directory of Open Access Journals (Sweden)

    Yang Chen

    2011-01-01

    Full Text Available Edge-preserving Bayesian restorations using nonquadratic priors are often inefficient in restoring continuous variations and tend to produce block artifacts around edges in ill-posed inverse image restorations. To overcome this, we have proposed a spatial adaptive (SA prior with improved performance. However, this SA prior restoration suffers from high computational cost and the unguaranteed convergence problem. Concerning these issues, this paper proposes a Large-scale Total Patch Variation (LS-TPV Prior model for Bayesian image restoration. In this model, the prior for each pixel is defined as a singleton conditional probability, which is in a mixture prior form of one patch similarity prior and one weight entropy prior. A joint MAP estimation is thus built to ensure the iteration monotonicity. The intensive calculation of patch distances is greatly alleviated by the parallelization of Compute Unified Device Architecture(CUDA. Experiments with both simulated and real data validate the good performance of the proposed restoration.

  8. A Total Variation Regularization Based Super-Resolution Reconstruction Algorithm for Digital Video

    Directory of Open Access Journals (Sweden)

    Zhang Liangpei

    2007-01-01

    Full Text Available Super-resolution (SR reconstruction technique is capable of producing a high-resolution image from a sequence of low-resolution images. In this paper, we study an efficient SR algorithm for digital video. To effectively deal with the intractable problems in SR video reconstruction, such as inevitable motion estimation errors, noise, blurring, missing regions, and compression artifacts, the total variation (TV regularization is employed in the reconstruction model. We use the fixed-point iteration method and preconditioning techniques to efficiently solve the associated nonlinear Euler-Lagrange equations of the corresponding variational problem in SR. The proposed algorithm has been tested in several cases of motion and degradation. It is also compared with the Laplacian regularization-based SR algorithm and other TV-based SR algorithms. Experimental results are presented to illustrate the effectiveness of the proposed algorithm.

  9. Anisotropic Total Variation Regularized L^1-Approximation and Denoising/Deblurring of 2D Bar Codes

    CERN Document Server

    Choksi, Rustum; Oberman, Adam

    2010-01-01

    We consider variations of the Rudin-Osher-Fatemi functional which are particularly well-suited to denoising and deblurring of 2D bar codes. These functionals consist of an anisotropic total variation favoring rectangles and a fidelity term which measure the L^1 distance to the signal, both with and without the presence of a deconvolution operator. Based upon the existence of a certain associated vector field, we find necessary and sufficient conditions for a function to be a minimizer. We apply these results to 2D bar codes to find explicit regimes ---in terms of the fidelity parameter and smallest length scale of the bar codes--- for which a perfect bar code is recoverable via minimization of the functionals. Via a discretization reformulated as a linear program, we perform numerical experiments for all functionals demonstrating their denoising and deblurring capabilities.

  10. The numerical solution of total variation minimization problems in image processing

    Energy Technology Data Exchange (ETDEWEB)

    Vogel, C.R.; Oman, M.E. [Montana State Univ., Bozeman, MT (United States)

    1994-12-31

    Consider the minimization of penalized least squares functionals of the form: f(u) = 1/2 ({parallel}Au {minus} z{parallel}){sup 2} + {alpha}{integral}{sub {Omega}}{vert_bar}{del}u{vert_bar}dx. Here A is a bounded linear operator, z represents data, {parallel} {center_dot} {parallel} is a Hilbert space norm, {alpha} is a positive parameter, {integral}{sub {Omega}}{vert_bar}{del}u{vert_bar} dx represents the total variation (TV) of a function u {element_of} BV ({Omega}), the class of functions of bounded variation on a bounded region {Omega}, and {vert_bar} {center_dot} {vert_bar} denotes Euclidean norm. In image processing, u represents an image which is to be recovered from noisy data z. Certain {open_quotes}blurring processes{close_quotes} may be represented by the action of an operator A on the image u.

  11. Adaptive Second-Order Total Variation: An Approach Aware of Slope Discontinuities

    KAUST Repository

    Lenzen, Frank

    2013-01-01

    Total variation (TV) regularization, originally introduced by Rudin, Osher and Fatemi in the context of image denoising, has become widely used in the field of inverse problems. Two major directions of modifications of the original approach were proposed later on. The first concerns adaptive variants of TV regularization, the second focuses on higher-order TV models. In the present paper, we combine the ideas of both directions by proposing adaptive second-order TV models, including one anisotropic model. Experiments demonstrate that introducing adaptivity results in an improvement of the reconstruction error. © 2013 Springer-Verlag.

  12. New attenuation correction for the HRRT using transmission scatter correction and total variation regularization

    DEFF Research Database (Denmark)

    Sibomana, Merence; Keller, Sune Høgild; Svarer, Claus

    2009-01-01

    tissue segmentation in these regions and the lack of scatter correction in the μ-map reconstruction. In this paper we describe and validate the new TXTV segmentation method (included in the HRRT_U 1.0 and 1.1 user software) aimed at solving the bias problem. Its improvements fall in two parts: Firstly......, it introduces the use of scatter correction, and secondly, it uses a simple threshold in combination with nonlinear total variation μ-map filtering. To validate the new transmission μ-map reconstruction with scatter correction and TXTV segmentation, we compared the average activity in 50 RoIs average...

  13. Accelerating cross-validation with total variation and its application to super-resolution imaging

    CERN Document Server

    Obuchi, Tomoyuki; Akiyama, Kazunori; Kabashima, Yoshiyuki

    2016-01-01

    We develop an approximation formula for the cross-validation error (CVE) of a sparse linear regression penalized by $\\ell_1$-norm and total variation terms, which is based on a perturbative expansion utilizing the largeness of both the data dimensionality and the model. The developed formula allows us to reduce the necessary computational cost of the CVE evaluation significantly. The practicality of the formula is tested through application to simulated black-hole image reconstruction on the event-horizon scale with super resolution. The results demonstrate that our approximation reproduces the CVE values obtained via literally conducted cross-validation with reasonably good precision.

  14. A Primal-Dual Approach for a Total Variation Wasserstein Flow

    KAUST Repository

    Benning, Martin

    2013-01-01

    We consider a nonlinear fourth-order diffusion equation that arises in denoising of image densities. We propose an implicit time-stepping scheme that employs a primal-dual method for computing the subgradient of the total variation seminorm. The constraint on the dual variable is relaxed by adding a penalty term, depending on a parameter that determines the weight of the penalisation. The paper is furnished with some numerical examples showing the denoising properties of the model considered. © 2013 Springer-Verlag.

  15. Box relaxation schemes in staggered discretizations for the dual formulation of total variation minimization.

    Science.gov (United States)

    Garamendi, Juan Francisco; Gaspar, Francisco José; Malpica, Norberto; Schiavi, Emanuele

    2013-05-01

    In this paper, we propose some new box relaxation numerical schemes on staggered grids to solve the stationary system of partial differential equations arising from the dual minimization problem associated with the total variation operator. We present in detail the numerical schemes for the scalar case and its generalization to multichannel (vectorial) images. Then, we discuss their implementation in digital image denoising. The results outperform the resolution of the dual equation based on the gradient descent approach and pave the way for more advanced numerical strategies.

  16. An Adaptive Total Generalized Variation Model with Augmented Lagrangian Method for Image Denoising

    Directory of Open Access Journals (Sweden)

    Chuan He

    2014-01-01

    Full Text Available We propose an adaptive total generalized variation (TGV based model, aiming at achieving a balance between edge preservation and region smoothness for image denoising. The variable splitting (VS and the classical augmented Lagrangian method (ALM are used to solve the proposed model. With the proposed adaptive model and ALM, the regularization parameter, which balances the data fidelity and the regularizer, is refreshed with a closed form in each iterate, and the image denoising can be accomplished without manual interference. Numerical results indicate that our method is effective in staircasing effect suppression and holds superiority over some other state-of-the-art methods both in quantitative and in qualitative assessment.

  17. Variations in the concentration of total human milk proteins in the first month of lactation

    Directory of Open Access Journals (Sweden)

    Mladenović Marija

    2007-01-01

    Full Text Available Introduction. Human milk proteins are maximally adapted to physiological needs of a neonate. Thus, depending on the speed of the neonatal growth and development, the content of milk proteins changes, both in quantity and quality. Objective. The study was conducted in order to determine variations of total protein concentrations in milk in the first and third lactation week in lactating mothers of term and preterm neonates. Also, we analyzed the influence of the mode of delivery, neonatal Apgar score and parity on the concentration of human milk proteins in both lactation phases. Method. The study aims were evaluated on the sample of 48 women, of whom 33 were mothers of term neonates and 15 of neonates born between the 34th to 37th gestational weeks. Total protein level of the lactation milk from the middle phase was determined using the standard laboratory method (Lowry et al., 1951, and the obtained differences were analyzed by t-test. Results. Total protein concentration in term colostrum was 17.60-45.17 g/l (X=24.71±5.19, while in preterm colostrum it was 28.39-73.30 g/l (X=39.17±11.08. The total protein level of mature milk in women who had term delivery was 11.90-22.11 g/l (X=16.39±2.96, while in women who had preterm delivery it was 14.50-44.19 g/l (X=23.25±8.96. The obtained results indicated that total protein concentration in women who had preterm delivery was significantly higher than that of women who had term delivery, both in the colostral and mature phase of lactation. (p<0.01. Also, the difference in the protein concentration was statistically highly significant (p<0.01 in the colostral and mature phase of lactation, both in women who had term and preterm delivery. Variations in the total protein level of human milk were not significant, depending on the prematurity stage, the mode and severity of delivery and parity, both in the first and third week of lactation. Conclusion. Our results show that total protein concentration

  18. A sparsity regularization and total variation based computational framework for the inverse medium problem in scattering

    Science.gov (United States)

    Bürgel, Florian; Kazimierski, Kamil S.; Lechleiter, Armin

    2017-06-01

    We present a fast computational framework for the inverse medium problem in scattering, i.e. we look at discretization, reconstruction and numerical performance. The Helmholtz equation in two and three dimensions is used as a physical model of scattering including point sources and plane waves as incident fields as well as near and far field measurements. For the reconstruction of the medium, we set up a rapid variational regularization scheme and indicate favorable choices of the various parameters. The underlying paradigm is, roughly speaking, to minimize the discrepancy between the reconstruction and measured data while, at the same time, taking into account various structural a-priori information via suitable penalty terms. In particular, the involved penalty terms are designed to promote information expected in real-world environments. To this end, a combination of sparsity promoting terms, total variation, and physical bounds of the inhomogeneous medium, e.g. positivity constraints, is employed in the regularization penalty. A primal-dual algorithm is used to solve the minimization problem related to the variational regularization. The computational feasibility, performance and efficiency of the proposed approach is demonstrated for synthetic as well as experimentally measured data.

  19. Total variation optimization for imaging through turbid media with transmission matrix

    Science.gov (United States)

    Gong, Changmei; Shao, Xiaopeng; Wu, Tengfei; Liu, Jietao; Zhang, Jianqi

    2016-12-01

    With the transmission matrix (TM) of the whole optical system measured, the image of the object behind a turbid medium can be recovered from its speckle field by means of an image reconstruction algorithm. Instead of Tikhonov regularization algorithm (TRA), the total variation minimization by augmented Lagrangian and alternating direction algorithms (TVAL3) is introduced to recover object images. As a total variation (TV)-based approach, TVAL3 allows to effectively damp more noise and preserve more edges compared with TRA, thus providing more outstanding image quality. Different levels of detector noise and TM-measurement noise are successively added to analyze the antinoise performance of these two algorithms. Simulation results show that TVAL3 is able to recover more details and suppress more noise than TRA under different noise levels, thus providing much more excellent image quality. Furthermore, whether it be detector noise or TM-measurement noise, the reconstruction images obtained by TVAL3 at SNR=15 dB are far superior to those by TRA at SNR=50 dB.

  20. Compressed sensing with gradient total variation for low-dose CBCT reconstruction

    Science.gov (United States)

    Seo, Chang-Woo; Cha, Bo Kyung; Jeon, Seongchae; Huh, Young; Park, Justin C.; Lee, Byeonghun; Baek, Junghee; Kim, Eunyoung

    2015-06-01

    This paper describes the improvement of convergence speed with gradient total variation (GTV) in compressed sensing (CS) for low-dose cone-beam computed tomography (CBCT) reconstruction. We derive a fast algorithm for the constrained total variation (TV)-based a minimum number of noisy projections. To achieve this task we combine the GTV with a TV-norm regularization term to promote an accelerated sparsity in the X-ray attenuation characteristics of the human body. The GTV is derived from a TV and enforces more efficient computationally and faster in convergence until a desired solution is achieved. The numerical algorithm is simple and derives relatively fast convergence. We apply a gradient projection algorithm that seeks a solution iteratively in the direction of the projected gradient while enforcing a non-negatively of the found solution. In comparison with the Feldkamp, Davis, and Kress (FDK) and conventional TV algorithms, the proposed GTV algorithm showed convergence in ≤18 iterations, whereas the original TV algorithm needs at least 34 iterations in reducing 50% of the projections compared with the FDK algorithm in order to reconstruct the chest phantom images. Future investigation includes improving imaging quality, particularly regarding X-ray cone-beam scatter, and motion artifacts of CBCT reconstruction.

  1. Compressed sensing with gradient total variation for low-dose CBCT reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Chang-Woo [Department of Radiation Convergence Engineering, College of Health Science, Yonsei University, Wonju (Korea, Republic of); Cha, Bo Kyung [Advanced Medical Device Research Center, Korea Electrotechnology Research Institute, Ansan (Korea, Republic of); Jeon, Seongchae, E-mail: sarim@keri.re.kr [Advanced Medical Device Research Center, Korea Electrotechnology Research Institute, Ansan (Korea, Republic of); Huh, Young [Advanced Medical Device Research Center, Korea Electrotechnology Research Institute, Ansan (Korea, Republic of); Park, Justin C. [Department of Radiation Oncology, University of Florida, Gainesville, FL (United States); Lee, Byeonghun [School of Information and Communication on Engineering, Inha University, Incheon (Korea, Republic of); Baek, Junghee; Kim, Eunyoung [School of the Global Media, Soongsil University, Seoul (Korea, Republic of)

    2015-06-01

    This paper describes the improvement of convergence speed with gradient total variation (GTV) in compressed sensing (CS) for low-dose cone–beam computed tomography (CBCT) reconstruction. We derive a fast algorithm for the constrained total variation (TV)-based a minimum number of noisy projections. To achieve this task we combine the GTV with a TV-norm regularization term to promote an accelerated sparsity in the X-ray attenuation characteristics of the human body. The GTV is derived from a TV and enforces more efficient computationally and faster in convergence until a desired solution is achieved. The numerical algorithm is simple and derives relatively fast convergence. We apply a gradient projection algorithm that seeks a solution iteratively in the direction of the projected gradient while enforcing a non-negatively of the found solution. In comparison with the Feldkamp, Davis, and Kress (FDK) and conventional TV algorithms, the proposed GTV algorithm showed convergence in ≤18 iterations, whereas the original TV algorithm needs at least 34 iterations in reducing 50% of the projections compared with the FDK algorithm in order to reconstruct the chest phantom images. Future investigation includes improving imaging quality, particularly regarding X-ray cone–beam scatter, and motion artifacts of CBCT reconstruction.

  2. Iterative image reconstruction that includes a total variation regularization for radial MRI.

    Science.gov (United States)

    Kojima, Shinya; Shinohara, Hiroyuki; Hashimoto, Takeyuki; Hirata, Masami; Ueno, Eiko

    2015-07-01

    This paper presents an iterative image reconstruction method for radial encodings in MRI based on a total variation (TV) regularization. The algebraic reconstruction method combined with total variation regularization (ART_TV) is implemented with a regularization parameter specifying the weight of the TV term in the optimization process. We used numerical simulations of a Shepp-Logan phantom, as well as experimental imaging of a phantom that included a rectangular-wave chart, to evaluate the performance of ART_TV, and to compare it with that of the Fourier transform (FT) method. The trade-off between spatial resolution and signal-to-noise ratio (SNR) was investigated for different values of the regularization parameter by experiments on a phantom and a commercially available MRI system. ART_TV was inferior to the FT with respect to the evaluation of the modulation transfer function (MTF), especially at high frequencies; however, it outperformed the FT with regard to the SNR. In accordance with the results of SNR measurement, visual impression suggested that the image quality of ART_TV was better than that of the FT for reconstruction of a noisy image of a kiwi fruit. In conclusion, ART_TV provides radial MRI with improved image quality for low-SNR data; however, the regularization parameter in ART_TV is a critical factor for obtaining improvement over the FT.

  3. Robust dynamic myocardial perfusion CT deconvolution using adaptive-weighted tensor total variation regularization

    Science.gov (United States)

    Gong, Changfei; Zeng, Dong; Bian, Zhaoying; Huang, Jing; Zhang, Xinyu; Zhang, Hua; Lu, Lijun; Feng, Qianjin; Liang, Zhengrong; Ma, Jianhua

    2016-03-01

    Dynamic myocardial perfusion computed tomography (MPCT) is a promising technique for diagnosis and risk stratification of coronary artery disease by assessing the myocardial perfusion hemodynamic maps (MPHM). Meanwhile, the repeated scanning of the same region results in a relatively large radiation dose to patients potentially. In this work, we present a robust MPCT deconvolution algorithm with adaptive-weighted tensor total variation regularization to estimate residue function accurately under the low-dose context, which is termed `MPD-AwTTV'. More specifically, the AwTTV regularization takes into account the anisotropic edge property of the MPCT images compared with the conventional total variation (TV) regularization, which can mitigate the drawbacks of TV regularization. Subsequently, an effective iterative algorithm was adopted to minimize the associative objective function. Experimental results on a modified XCAT phantom demonstrated that the present MPD-AwTTV algorithm outperforms and is superior to other existing deconvolution algorithms in terms of noise-induced artifacts suppression, edge details preservation and accurate MPHM estimation.

  4. Variation in the cost of care for primary total knee arthroplasties.

    Science.gov (United States)

    Haas, Derek A; Kaplan, Robert S

    2017-03-01

    The study examined the cost variation across 29 high-volume US hospitals and their affiliated orthopaedic surgeons for delivering a primary total knee arthroplasty without major complicating conditions. The hospitals had similar patient demographics, and more than 80% of them had statistically-similar Medicare risk-adjusted readmission and complication rates. Hospital and physician personnel costs were calculated using time-driven activity-based costing. Consumable supply costs, such as the prosthetic implant, were calculated using purchase prices, and postacute care costs were measured using either internal costs or external claims as reported by each hospital. Despite having similar patient demographics and readmission and complication rates, the average cost of care for total knee arthroplasty across the hospitals varied by a factor of about 2 to 1. Even after adjusting for differences in internal labor cost rates, the hospital at the 90th percentile of cost spent about twice as much as the one at the 10th percentile of cost. The large variation in costs among sites suggests major and multiple opportunities to transfer knowledge about process and productivity improvements that lower costs while simultaneously maintaining or improving outcomes.

  5. Total variation regularization of geodetically and geologically constrained block models for the Western United States

    Science.gov (United States)

    Evans, Eileen L.; Loveless, John P.; Meade, Brendan J.

    2015-08-01

    Geodetic observations of interseismic deformation in the Western United States provide constraints on microplate rotations, earthquake cycle processes, and slip partitioning across the Pacific-North America Plate boundary. These measurements may be interpreted using block models, in which the upper crust is divided into microplates bounded by faults that accumulate strain in a first-order approximation of earthquake cycle processes. The number and geometry of microplates are typically defined with boundaries representing a limited subset of the large number of potentially seismogenic faults. An alternative approach is to include a large number of potentially active faults bounding a dense array of microplates, and then algorithmically estimate the boundaries at which strain is localized. This approach is possible through the application of a total variation regularization (TVR) optimization algorithm, which simultaneously minimizes the L2 norm of data residuals and the L1 norm of the variation in the differential block motions. Applied to 3-D spherical block models, the TVR algorithm can be used to reduce the total variation between estimated rotation vectors, effectively grouping microplates that rotate together as larger blocks, and localizing fault slip on the boundaries of these larger block clusters. Here we develop a block model comprised of 137 microplates derived from published fault maps, and apply the TVR algorithm to identify the kinematically most important faults in the western United States. This approach reveals that of the 137 microplates considered, only 30 unique blocks are required to approximate deformation in the western United States at a residual level of <2 mm yr-1.

  6. NGP A stars - density variation, kinematics and the total mass density of the disk.

    Science.gov (United States)

    Knude, J.

    1997-11-01

    From an uvbyβ photometric survey of the north galactic pole where most A stars (A3-A9) above b=70°and brighter than B=11.5 were included we report the observed number density and age variation with z(pc). Stars between ~30 and 1300 pc are included. Our sample consists of 396 sharply defined main sequence/subgiant A stars following the Stroemgren - Crawford definition, no B, imA or F type stars are included, approximate color limits are 0.055-0.220 in (b-y)_0_. Proper motions from the PPM and CAMC catalogs are available for all stars implying U and V velocities. Radial velocities for a subsample (179 stars with b>75° and zentity but something like it is required for fitting the observations better than 10%. A consequence of the hump is that derivatives of the distribution display large variations. There seems to be significant differences between this distribution and the sum of four sech^2^s from the previous paragraph. W and U dispersions seem to have a constant ratio within the z range where we have both kinds of data. σ_U_ shows a homogeneous increase from ~20 to 45km/s within the completeness limit, with a 75pc independent binning, and to ~70km/s at 800pc. The complete U histogram may not be fitted with a single gaussian, three with different dispersions and mean values provide a reasonable fit. A more detailed binning shows dσ_U_/dz to change in a discontinous way at ~200pc. An application of the data might be a combination of the density and velocity data for a determination of the local, total disk density. But since velocity dispersions do obey some sort of age depence, the age - z variation turns out to be of importance and there is a very clear systematic trend of mean ages with z. The average age increases almost linearly to ~0.75Gyr, reached at 200pc, and then it stays constant within the completeness limit. On the average the younger A stars show a relative absence beyond 200pc implying that very different velocity dispersions might be seen on

  7. Interannual variation patterns of total ozone and lower stratospheric temperature in observations and model simulations

    Directory of Open Access Journals (Sweden)

    W. Steinbrecht

    2006-01-01

    Full Text Available We report results from a multiple linear regression analysis of long-term total ozone observations (1979 to 2000, by TOMS/SBUV, of temperature reanalyses (1958 to 2000, NCEP, and of two chemistry-climate model simulations (1960 to 1999, by ECHAM4.L39(DLR/CHEM (=E39/C, and MAECHAM4-CHEM. The model runs are transient experiments, where observed sea surface temperatures, increasing source gas concentrations (CO2, CFCs, CH4, N2O, NOx, 11-year solar cycle, volcanic aerosols and the quasi-biennial oscillation (QBO are all accounted for. MAECHAM4-CHEM covers the atmosphere from the surface up to 0.01 hPa (≈80 km. For a proper representation of middle atmosphere (MA dynamics, it includes a parametrization for momentum deposition by dissipating gravity wave spectra. E39/C, on the other hand, has its top layer centered at 10 hPa (≈30 km. It is targeted on processes near the tropopause, and has more levels in this region. Despite some problems, both models generally reproduce the observed amplitudes and much of the observed low-latitude patterns of the various modes of interannual variability in total ozone and lower stratospheric temperature. In most aspects MAECHAM4-CHEM performs slightly better than E39/C. MAECHAM4-CHEM overestimates the long-term decline of total ozone, whereas underestimates the decline over Antarctica and at northern mid-latitudes. The true long-term decline in winter and spring above the Arctic may be underestimated by a lack of TOMS/SBUV observations in winter, particularly in the cold 1990s. Main contributions to the observed interannual variations of total ozone and lower stratospheric temperature at 50 hPa come from a linear trend (up to -10 DU/decade at high northern latitudes, up to -40 DU/decade at high southern latitudes, and around -0.7 K/decade over much of the globe, from the intensity of the polar vortices (more than 40 DU, or 8 K peak to peak, the QBO (up to 20 DU, or 2 K peak to peak, and from

  8. Total Variation Regularization Algorithms for Images Corrupted with Different Noise Models: A Review

    Directory of Open Access Journals (Sweden)

    Paul Rodríguez

    2013-01-01

    Full Text Available Total Variation (TV regularization has evolved from an image denoising method for images corrupted with Gaussian noise into a more general technique for inverse problems such as deblurring, blind deconvolution, and inpainting, which also encompasses the Impulse, Poisson, Speckle, and mixed noise models. This paper focuses on giving a summary of the most relevant TV numerical algorithms for solving the restoration problem for grayscale/color images corrupted with several noise models, that is, Gaussian, Salt & Pepper, Poisson, and Speckle (Gamma noise models as well as for the mixed noise scenarios, such the mixed Gaussian and impulse model. We also include the description of the maximum a posteriori (MAP estimator for each model as well as a summary of general optimization procedures that are typically used to solve the TV problem.

  9. A Compton scattering image reconstruction algorithm based on total variation minimization

    Institute of Scientific and Technical Information of China (English)

    Li Shou-Peng; Wang Lin-Yuan; Yan Bin; Li Lei; Liu Yong-Jun

    2012-01-01

    Compton scattering imaging is a novel radiation imaging method using scattered photons.Its main characteristics are detectors that do not have to be on the opposite side of the source,so avoiding the rotation process.The reconstruction problem of Compton scattering imaging is the inverse problem to solve electron densities from nonlinear equations,which is ill-posed.This means the solution exhibits instability and sensitivity to noise or erroneous measurements.Using the theory for reconstruction of sparse images,a reconstruction algorithm based on total variation minimization is proposed.The reconstruction problem is described as an optimization problem with nonlinear data-consistency constraint.The simulated results show that the proposed algorithm could reduce reconstruction error and improve image quality,especially when there are not enough measurements.

  10. Denoising of gravitational-wave signal GW150914 via total-variation methods

    CERN Document Server

    Torres-Forné, Alejandro; Font, José A; Ibáñez, José M

    2016-01-01

    We apply a regularized Rudin-Osher-Fatemi total variation (TV) method to denoise the transient gravitational wave signal GW150914. We have previously applied TV techniques to denoise numerically generated grav- itational waves embedded in additive Gaussian noise, obtaining satisfactory results irrespective of the signal morphology or astrophysical origin. We find that the non-Gaussian, non-stationary noise from the gravitational wave event GW150914 can also be successfully removed with TV-denoising methods. The quality of the de- noised waveform is comparable to that obtained with the Bayesian approach used in the discovery paper [1]. TV-denoising techniques may thus offer an additional viable approach for waveform reconstruction.

  11. Total variation regularization for bioluminescence tomography with the split Bregman method.

    Science.gov (United States)

    Feng, Jinchao; Qin, Chenghu; Jia, Kebin; Zhu, Shouping; Liu, Kai; Han, Dong; Yang, Xin; Gao, Quansheng; Tian, Jie

    2012-07-01

    Regularization methods have been broadly applied to bioluminescence tomography (BLT) to obtain stable solutions, including l2 and l1 regularizations. However, l2 regularization can oversmooth reconstructed images and l1 regularization may sparsify the source distribution, which degrades image quality. In this paper, the use of total variation (TV) regularization in BLT is investigated. Since a nonnegativity constraint can lead to improved image quality, the nonnegative constraint should be considered in BLT. However, TV regularization with a nonnegativity constraint is extremely difficult to solve due to its nondifferentiability and nonlinearity. The aim of this work is to validate the split Bregman method to minimize the TV regularization problem with a nonnegativity constraint for BLT. The performance of split Bregman-resolved TV (SBRTV) based BLT reconstruction algorithm was verified with numerical and in vivo experiments. Experimental results demonstrate that the SBRTV regularization can provide better regularization quality over l2 and l1 regularizations.

  12. Song Recommendation with Non-Negative Matrix Factorization and Graph Total Variation

    CERN Document Server

    Benzi, Kirell; Bresson, Xavier; Vandergheynst, Pierre

    2016-01-01

    This work formulates a novel song recommender system as a matrix completion problem that benefits from collaborative filtering through Non-negative Matrix Factorization (NMF) and content-based filtering via total variation (TV) on graphs. The graphs encode both playlist proximity information and song similarity, using a rich combination of audio, meta-data and social features. As we demonstrate, our hybrid recommendation system is very versatile and incorporates several well-known methods while outperforming them. Particularly, we show on real-world data that our model overcomes w.r.t. two evaluation metrics the recommendation of models solely based on low-rank information, graph-based information or a combination of both.

  13. Alternating Direction Total Variation Image Reconstruction and Practical Decomposition for Dual-energy Computed Tomography

    CERN Document Server

    Li, Lei; Wang, Linyuan; Yan, Bin; Zhang, Hanming; Zheng, Zhizhong; Zhang, Wenkun; Lu, Wanli; Hu, Guoen

    2016-01-01

    Dual-energy computed tomography (DECT) has shown great potential and promising applications in advanced imaging fields for its capabilities of material decomposition. However, image reconstructions and decompositions under sparse views dataset suffers severely from multi factors, such as insufficiencies of data, appearances of noise, and inconsistencies of observations. Under sparse views, conventional filtered back-projection type reconstruction methods fails to provide CT images with satisfying quality. Moreover, direct image decomposition is unstable and meet with noise boost even with full views dataset. This paper proposes an iterative image reconstruction algorithm and a practical image domain decomposition method for DECT. On one hand, the reconstruction algorithm is formulated as an optimization problem, which containing total variation regularization term and data fidelity term. The alternating direction method is utilized to design the corresponding algorithm which shows faster convergence speed com...

  14. A sequential solution for anisotropic total variation image denoising with interval constraints

    Science.gov (United States)

    Xu, Jingyan; Noo, Frédéric

    2017-09-01

    We show that two problems involving the anisotropic total variation (TV) and interval constraints on the unknown variables admit, under some conditions, a simple sequential solution. Problem 1 is a constrained TV penalized image denoising problem; problem 2 is a constrained fused lasso signal approximator. The sequential solution entails finding first the solution to the unconstrained problem, and then applying a thresholding to satisfy the constraints. If the interval constraints are uniform, this sequential solution solves problem 1. If the interval constraints furthermore contain zero, the sequential solution solves problem 2. Here uniform interval constraints refer to all unknowns being constrained to the same interval. A typical example of application is image denoising in x-ray CT, where the image intensities are non-negative as they physically represent linear attenuation coefficient in the patient body. Our results are simple yet seem unknown; we establish them using the Karush–Kuhn–Tucker conditions for constrained convex optimization.

  15. A constrained, total-variation minimization algorithm for low-intensity X-ray CT

    CERN Document Server

    Sidky, Emil Y; Ullberg, Christer; Pan, Xiaochuan

    2010-01-01

    Purpose: We develop an iterative image-reconstruction algorithm for application to low-intensity computed tomography (CT) projection data, which is based on constrained, total-variation (TV) minimization. The algorithm design focuses on recovering structure on length scales comparable to a detector-bin width. Method: Recovering the resolution on the scale of a detector bin, requires that pixel size be much smaller than the bin width. The resulting image array contains many more pixels than data, and this undersampling is overcome with a combination of Fourier upsampling of each projection and the use of constrained, TV-minimization, as suggested by compressive sensing. The presented pseudo-code for solving constrained, TV-minimization is designed to yield an accurate solution to this optimization problem within 100 iterations. Results: The proposed image-reconstruction algorithm is applied to a low-intensity scan of a rabbit with a thin wire, to test resolution. The proposed algorithm is compared with filtere...

  16. Suppression of MRI Truncation Artifacts Using Total Variation Constrained Data Extrapolation

    Directory of Open Access Journals (Sweden)

    Kai Tobias Block

    2008-01-01

    Full Text Available The finite sampling of k-space in MRI causes spurious image artifacts, known as Gibbs ringing, which result from signal truncation at the border of k-space. The effect is especially visible for acquisitions at low resolution and commonly reduced by filtering at the expense of image blurring. The present work demonstrates that the simple assumption of a piecewise-constant object can be exploited to extrapolate the data in k-space beyond the measured part. The method allows for a significant reduction of truncation artifacts without compromising resolution. The assumption translates into a total variation minimization problem, which can be solved with a nonlinear optimization algorithm. In the presence of substantial noise, a modified approach offers edge-preserving denoising by allowing for slight deviations from the measured data in addition to supplementing data. The effectiveness of these methods is demonstrated with simulations as well as experimental data for a phantom and human brain in vivo.

  17. Box-constrained Total-variation Image Restoration with Automatic Parameter Estimation

    Institute of Scientific and Technical Information of China (English)

    HE Chuan; HU Chang-Hua; ZHANG Wei; SHI Biao

    2014-01-01

    The box constraints in image restoration have been arousing great attention, since the pixels of a digital image can attain only a finite number of values in a given dynamic range. This paper studies the box-constrained total-variation (TV) image restoration problem with automatic regularization parameter estimation. By adopting the variable splitting technique and introducing some auxiliary variables, the box-constrained TV minimization problem is decomposed into a sequence of subproblems which are easier to solve. Then the alternating direction method (ADM) is adopted to solve the related subproblems. By means of Morozov0s discrepancy principle, the regularization parameter can be updated adaptively in a closed form in each iteration. Image restoration experiments indicate that with our strategies, more accurate solutions are achieved, especially for image with high percentage of pixel values lying on the boundary of the given dynamic range.

  18. Total Variation Minimization Based Compressive Wideband Spectrum Sensing for Cognitive Radios

    CERN Document Server

    Liu, Yipeng

    2011-01-01

    Wideband spectrum sensing is a critical component of a functioning cognitive radio system. Its major challenge is the too high sampling rate requirement. Compressive sensing (CS) promises to be able to deal with it. Nearly all the current CS based compressive wideband spectrum sensing methods exploit only the frequency sparsity to perform. Motivated by the achievement of a fast and robust detection of the wideband spectrum change, total variation mnimization is incorporated to exploit the temporal and frequency structure information to enhance the sparse level. As a sparser vector is obtained, the spectrum sensing period would be shorten and sensing accuracy would be enhanced. Both theoretical evaluation and numerical experiments can demonstrate the performance improvement.

  19. Fast Total-Variation Image Deconvolution with Adaptive Parameter Estimation via Split Bregman Method

    Directory of Open Access Journals (Sweden)

    Chuan He

    2014-01-01

    Full Text Available The total-variation (TV regularization has been widely used in image restoration domain, due to its attractive edge preservation ability. However, the estimation of the regularization parameter, which balances the TV regularization term and the data-fidelity term, is a difficult problem. In this paper, based on the classical split Bregman method, a new fast algorithm is derived to simultaneously estimate the regularization parameter and to restore the blurred image. In each iteration, the regularization parameter is refreshed conveniently in a closed form according to Morozov’s discrepancy principle. Numerical experiments in image deconvolution show that the proposed algorithm outperforms some state-of-the-art methods both in accuracy and in speed.

  20. A Dictionary Learning Method with Total Generalized Variation for MRI Reconstruction.

    Science.gov (United States)

    Lu, Hongyang; Wei, Jingbo; Liu, Qiegen; Wang, Yuhao; Deng, Xiaohua

    2016-01-01

    Reconstructing images from their noisy and incomplete measurements is always a challenge especially for medical MR image with important details and features. This work proposes a novel dictionary learning model that integrates two sparse regularization methods: the total generalized variation (TGV) approach and adaptive dictionary learning (DL). In the proposed method, the TGV selectively regularizes different image regions at different levels to avoid oil painting artifacts largely. At the same time, the dictionary learning adaptively represents the image features sparsely and effectively recovers details of images. The proposed model is solved by variable splitting technique and the alternating direction method of multiplier. Extensive simulation experimental results demonstrate that the proposed method consistently recovers MR images efficiently and outperforms the current state-of-the-art approaches in terms of higher PSNR and lower HFEN values.

  1. Accelerated gradient methods for total-variation-based CT image reconstruction

    DEFF Research Database (Denmark)

    Jørgensen, Jakob Heide; Jensen, Tobias Lindstrøm; Hansen, Per Christian

    2011-01-01

    Total-variation (TV)-based CT image reconstruction has shown experimentally to be capable of producing accurate reconstructions from sparse-view data. In particular TV-based reconstruction is very well suited for images with piecewise nearly constant regions. Computationally, however, TV-based....... In the present work we address the question of how to reduce the number of gradient method iterations needed to achieve a high-accuracy TV reconstruction. We consider the use of two accelerated gradient-based methods, GPBB and UPN, to solve the 3D-TV minimization problem in CT image reconstruction. The former...... incorporates several heuristics from the optimization literature such as Barzilai-Borwein (BB) step size selection and nonmonotone line search. The latter uses a cleverly chosen sequence of auxiliary points to achieve a better convergence rate. The methods are memory efficient and equipped with a stopping...

  2. WHAT CAUSES THE INTER-SOLAR-CYCLE VARIATION OF TOTAL SOLAR IRRADIANCE?

    Energy Technology Data Exchange (ETDEWEB)

    Xiang, N. B.; Kong, D. F., E-mail: nanbin@ynao.ac.cn [National Astronomical Observatories/Yunnan Observatory, CAS, Kunming 650011 (China)

    2015-12-15

    The Physikalisch Meteorologisches Observatorium Davos total solar irradiance (TSI), Active Cavity Radiometer Irradiance Monitoring TSI, and Royal Meteorological Institute of Belgium TSI are three typical TSI composites. Magnetic Plage Strength Index (MPSI) and Mount Wilson Sunspot Index (MWSI) should indicate the weak and strong magnetic field activity on the solar full disk, respectively. Cross-correlation (CC) analysis of MWSI with three TSI composites shows that TSI should be weakly correlated with MWSI, and not be in phase with MWSI at timescales of solar cycles. The wavelet coherence (WTC) and partial wavelet coherence (PWC) of TSI with MWSI indicate that the inter-solar-cycle variation of TSI is also not related to solar strong magnetic field activity, which is represented by MWSI. However, CC analysis of MPSI with three TSI composites indicates that TSI should be moderately correlated and accurately in phase with MPSI at timescales of solar cycles, and that the statistical significance test indicates that the correlation coefficient of three TSI composites with MPSI is statistically significantly higher than that of three TSI composites with MWSI. Furthermore, the cross wavelet transform (XWT) and WTC of TSI with MPSI show that the TSI is highly related and actually in phase with MPSI at a timescale of a solar cycle as well. Consequently, the CC analysis, XWT, and WTC indicate that the solar weak magnetic activity on the full disk, which is represented by MPSI, dominates the inter-solar-cycle variation of TSI.

  3. Multiscale Tikhonov-Total Variation Image Restoration Using Spatially Varying Edge Coherence Exponent.

    Science.gov (United States)

    Prasath, V B Surya; Vorotnikov, Dmitry; Pelapur, Rengarajan; Jose, Shani; Seetharaman, Guna; Palaniappan, Kannappan

    2015-12-01

    Edge preserving regularization using partial differential equation (PDE)-based methods although extensively studied and widely used for image restoration, still have limitations in adapting to local structures. We propose a spatially adaptive multiscale variable exponent-based anisotropic variational PDE method that overcomes current shortcomings, such as over smoothing and staircasing artifacts, while still retaining and enhancing edge structures across scale. Our innovative model automatically balances between Tikhonov and total variation (TV) regularization effects using scene content information by incorporating a spatially varying edge coherence exponent map constructed using the eigenvalues of the filtered structure tensor. The multiscale exponent model we develop leads to a novel restoration method that preserves edges better and provides selective denoising without generating artifacts for both additive and multiplicative noise models. Mathematical analysis of our proposed method in variable exponent space establishes the existence of a minimizer and its properties. The discretization method we use satisfies the maximum-minimum principle which guarantees that artificial edge regions are not created. Extensive experimental results using synthetic, and natural images indicate that the proposed multiscale Tikhonov-TV (MTTV) and dynamical MTTV methods perform better than many contemporary denoising algorithms in terms of several metrics, including signal-to-noise ratio improvement and structure preservation. Promising extensions to handle multiplicative noise models and multichannel imagery are also discussed.

  4. Efficient and Effective Total Variation Image Super-Resolution: A Preconditioned Operator Splitting Approach

    Directory of Open Access Journals (Sweden)

    Li-Li Huang

    2011-01-01

    Full Text Available Super-resolution is a fusion process for reconstructing a high-resolution image from a set of low-resolution images. This paper proposes a novel approach to image super-resolution based on total variation (TV regularization. We applied the Douglas-Rachford splitting technique to the constrained TV-based variational SR model which is separated into three subproblems that are easy to solve. Then, we derive an efficient and effective iterative scheme, which includes a fast iterative shrinkage/thresholding algorithm for denoising problem, a very simple noniterative algorithm for fusion part, and linear equation systems for deblurring process. Moreover, to speed up convergence, we provide an accelerated scheme based on precondition design of initial guess and forward-backward splitting technique which yields linear systems of equations with a nice structure. The proposed algorithm shares a remarkable simplicity together with a proven global rate of convergence which is significantly better than currently known lagged diffusivity fixed point iteration algorithm and fast decoupling algorithm by exploiting the alternating minimizing approach. Experimental results are presented to illustrate the effectiveness of the proposed algorithm.

  5. A Fast Alternating Minimization Algorithm for Nonlocal Vectorial Total Variational Multichannel Image Denoising

    Directory of Open Access Journals (Sweden)

    Rubing Xi

    2014-01-01

    Full Text Available The variational models with nonlocal regularization offer superior image restoration quality over traditional method. But the processing speed remains a bottleneck due to the calculation quantity brought by the recent iterative algorithms. In this paper, a fast algorithm is proposed to restore the multichannel image in the presence of additive Gaussian noise by minimizing an energy function consisting of an l2-norm fidelity term and a nonlocal vectorial total variational regularization term. This algorithm is based on the variable splitting and penalty techniques in optimization. Following our previous work on the proof of the existence and the uniqueness of the solution of the model, we establish and prove the convergence properties of this algorithm, which are the finite convergence for some variables and the q-linear convergence for the rest. Experiments show that this model has a fabulous texture-preserving property in restoring color images. Both the theoretical derivation of the computation complexity analysis and the experimental results show that the proposed algorithm performs favorably in comparison to the widely used fixed point algorithm.

  6. Total variation superiorization in dual-energy CT reconstruction for proton therapy treatment planning

    Science.gov (United States)

    Zhu, Jiahua; Penfold, Scott

    2017-04-01

    Proton therapy is a precise form of radiotherapy in which the range of an energetic beam of protons within a patient must be accurately known. The current approach based on single-energy computed tomography (SECT) can lead to uncertainties in the proton range of approximately 3%. This range of uncertainty may lead to under-dosing of the tumour or over-dosing of healthy tissues. Dual-energy CT (DECT) theoretically has the potential to reduce these range uncertainties by quantifying electron density and the effective atomic number. In practice, however, DECT images reconstructed with filtered backprojection (FBP) tend to suffer from high levels of noise. The objective of the current work was to examine the effect of total variation superiorization (TVS) on proton therapy planning accuracy when compared with FBP. A virtual CT scanner was created with the Monte Carlo toolkit Geant4. Tomographic images were reconstructed with FBP and TVS combined with diagonally relaxed orthogonal projections (TVS-DROP). A total variation minimization (TVM) filter was also applied to the image reconstructed with FBP (FBP-TVM). Quantitative accuracy and variance of proton relative stopping power (RSP) derived from each image set was assessed. Mean RSPs were comparable with each image; however, the standard deviation of pixel values with TVS-DROP was reduced by a factor of 0.44 compared with the FBP image and a factor of 0.66 when compared with the FBP-TVM image. Proton doses calculated with the TVS-DROP image set were also better able to predict a reference dose distribution when compared with the FBP and FBP-TVM image sets. The study demonstrated the potential advantages of TVS-DROP as an image reconstruction method for DECT applied to proton therapy treatment planning.

  7. Total column density variations of ozone (O3) in presence of different types of clouds

    Indian Academy of Sciences (India)

    G S Meena

    2010-06-01

    The zenith sky scattered light spectra were carried out using zenith sky UV-visible spectrometer in clear and cloudy sky conditions during May–November 2000 over the tropical station Pune (18°32′N, 73°51′E). These scattered spectra are obtained in the spectral range 462–498 nm between 75° and 92° solar zenith angles (SZAs). The slant column densities (SCDs) as well as total column densities (TCDs) of NO2, O3, H2O and O4 are derived with different SZAs in clear and cloudy sky conditions. The large enhancements and reductions in TCDs of the above gases are observed in thick cumulonimbus (Cb) clouds and thin high cirrus (Ci) clouds, respectively, compared to clear sky conditions. The enhancements in TCDs of O3 appear to be due to photon diffusion, multiple Mie-scattering and multiple reflections between layered clouds or isolated patches of optically thick clouds. The reductions in TCDs due to optically thin clouds are noticed during the above period. The variations in TCDs of O3 measured under cloudy sky are discussed with total cloud cover (octas) of different types of clouds such as low clouds (CL), medium clouds (CM) and high clouds (CH) during May–November 2000. The variations in TCDs of O3 measured in cloudy sky conditions are found to be well matched with cloud sensitive parameter colour index (CI) and found to be in good correlation. The TCDcloudy are derived using airmass factors (AMFs) computed without considering cloud cover and CI in radiative transfer (RT) model, whereas TCDmodel are derived using AMFs computed with considering cloud cover, cloud height and CI in RT model. The TCDmodel is the column density of illuminated cloudy effect. A good agreement is observed between TCDmodel, TCDDob and TCDGOME.

  8. Joint L1 and total variation regularization for fluorescence molecular tomography

    Science.gov (United States)

    Dutta, Joyita; Ahn, Sangtae; Li, Changqing; Cherry, Simon R.; Leahy, Richard M.

    2012-03-01

    Fluorescence molecular tomography (FMT) is an imaging modality that exploits the specificity of fluorescent biomarkers to enable 3D visualization of molecular targets and pathways in vivo in small animals. Owing to the high degree of absorption and scattering of light through tissue, the FMT inverse problem is inherently ill-conditioned making image reconstruction highly susceptible to the effects of noise and numerical errors. Appropriate priors or penalties are needed to facilitate reconstruction and to restrict the search space to a specific solution set. Typically, fluorescent probes are locally concentrated within specific areas of interest (e.g., inside tumors). The commonly used L2 norm penalty generates the minimum energy solution, which tends to be spread out in space. Instead, we present here an approach involving a combination of the L1 and total variation norm penalties, the former to suppress spurious background signals and enforce sparsity and the latter to preserve local smoothness and piecewise constancy in the reconstructed images. We have developed a surrogate-based optimization method for minimizing the joint penalties. The method was validated using both simulated and experimental data obtained from a mouse-shaped phantom mimicking tissue optical properties and containing two embedded fluorescent sources. Fluorescence data were collected using a 3D FMT setup that uses an EMCCD camera for image acquisition and a conical mirror for full-surface viewing. A range of performance metrics was utilized to evaluate our simulation results and to compare our method with the L1, L2 and total variation norm penalty-based approaches. The experimental results were assessed using the Dice similarity coefficients computed after co-registration with a CT image of the phantom.

  9. Variations of Microbial Communities and the Contents and Isotopic Compositions of Total Organic Carbon and Total Nitrogen in Soil Samples during Their Preservation

    Institute of Scientific and Technical Information of China (English)

    TAO Qianye; LI Yumei; WANG Guo'an; QIAO Yuhui; LIU Tung-Sheng

    2009-01-01

    Semi-sealed preservation of soil samples at difierent moisture of 4%and 23%,respectively, was simulated to observe the variations of soil microbiaI communities and determine the contents and isotopic compositions of the total organic carbon and total nitrogen on the 7th and 30th day, respectively.The results show that during preservation,the quantity of microbial communities tended to increase first and then decrease,with a wider variation range at higher moisture(23%).At the moisture content of 23%,the microbial communities became more active on the 7th day.but less after 30 days,and their activity Was stable with little fluctuation at the moisture content of 4%.However. there were no significant changes in the contents and isotopic compositions of the total organic carbon and total nitrogen.During preservation.the responses of soil microbes to the environment are more sensitive to changes in the total nitrogen and organic carbon contents.It is thus suggested that the variations of microbial communities have not exerted remarkable impacts on the isotope compositions of the total nitrogen and total organic carbon.

  10. Total knee arthroplasty: indication of blood transfusion according to hematimetric variation and clinical symptoms of hypoperfusion,

    Directory of Open Access Journals (Sweden)

    Rodrigo Tavares Cardozo

    2014-10-01

    Full Text Available Objective:To analyze the relationship between hematimetric variation and the presence of clinical symptoms of hypoperfusion for indicating blood transfusion in patients undergoing total knee arthroplasty.Methods:A retrospective analysis was conducted on data gathered from the medical files of 55 patients with a diagnosis of gonarthrosis, who underwent total knee arthroplasty at a hospital orthopedics and traumatology service between February 2011 and December 2012. The patients studied presented unilateral joint degeneration and fitted into the indications for surgical treatment. All the patients underwent a preoperative cardiological evaluation, presenting a pattern of ASA I–III and absence of blood dyscrasia, and preoperative hemoglobin measurements were made. However, no minimum hematimetric value was established for the surgical treatment; there were only clinical criteria for blood perfusion.Results:Among the 55 patients, 35 were female and 20 were male, and the mean age was 68 years. Six patients underwent homologous blood transfusion, because of their clinical condition of tissue hypoperfusion, persistent hypotension, loss of consciousness, sweating and coercible vomiting. They presented postoperative hemoglobin of 7.5–8.8 g/dL.Conclusion:For patients with falls in hemoglobin counts greater than 20% and values lower than 9 g/dL after the surgery, there is a possible need for blood transfusion, which should only be indicated when accompanied by major symptoms of tissue hypoperfusion.

  11. Magnetic Field - Secular Variation of the Total Field Component for the Epoch 2010.0 - Direct Download

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This map layer shows lines of equal annual change (secular variation), in the total field intensity of the Earth's magnetic field, derived from the International...

  12. Seasonal Variations in Total Antioxidant Capacity and Total Phenolics Content of Leaves of Phyllostachys Taxa Using Different Extraction Methods

    Directory of Open Access Journals (Sweden)

    András NEMÉNYI

    2014-06-01

    Full Text Available Changes in total phenolic content (TP and total antioxidant capacity (AC during the vegetation period (April-November were analysed in Phyllostachys aureosulcata f. aureocaulis (PAA, P. flexuosa (PF, P. humilis (PH, P. sulphurea var. sulphurea (PSS. Different extraction methods were compared: infusion or decoction with water or aqueous methanol. The highest significant value for TP was measured in the case of infusion at 90 °C for 5 min, which lead to the highest value for AC. During the vegetation period the highest values of TP were measured in April and May in the case of PAA (409.5; 314.9 and 258.7; 119.0 μg GA/ml and PH (388.4; 411.6 and 252.9; 253.3 μg GA/ml. There was a clear trend in the changes of TP, with high values in April and November and a peak during August-September. Similar to TP, the highest values of AC were measured in April and May in PH (519.7; 566.3 and 513.5; 510.4 μg AA/ml and PAA (534.5; 337.8 and 394.9; 275.4 μg AA/ml. We compared the change of TP in all taxa with stress index values derived from daily maximum and minimum air temperature, cumulative precipitation plus irrigation and cumulative evapotranspiration values. A close correlation R2 = 0.32 (p=0.001 was found between stress index values and the change in TP of all taxa. The correlation is even closer R2 = 0.52 (p=0.001 with PF, PH and PSS. Our results with PAA can be explained by possible inter/intra-specific differences in freeze tolerance and cold-acclimation.

  13. GPU-based Cone Beam CT Reconstruction via Total Variation Regularization

    CERN Document Server

    Jia, Xun; Lewis, John; Li, Ruijiang; Gu, Xuejun; Men, Chunhua; Jiang, Steve B

    2010-01-01

    Cone-beam CT (CBCT) reconstruction is of central importance in image guided radiation therapy due to its broad applications in many clinical contexts. However, the high image dose in CBCT scans is a clinical concern, especially when it is used repeatedly for patient setup purposes before each radiotherapy treatment fraction. A desire for lower imaging does has motivated a vast amount of interest in the CBCT reconstruction based on a small number of X-ray projections. Recently, advances in image processing and compressed sensing have led to tremendous success in recovering signals based on extremely low sampling rates, laying the mathematical foundation for reconstructing CBCT from few projections. In this paper, we present our recent development on a GPU-based iterative algorithm for the highly under-sampled CBCT reconstruction problem. We considered an energy functional consisting of a data fidelity term and a regularization term of a total variation norm. In order to solve our model, we developed a modified...

  14. Investigation of optimization-based reconstruction with an image-total-variation constraint in PET

    Science.gov (United States)

    Zhang, Zheng; Ye, Jinghan; Chen, Buxin; Perkins, Amy E.; Rose, Sean; Sidky, Emil Y.; Kao, Chien-Min; Xia, Dan; Tung, Chi-Hua; Pan, Xiaochuan

    2016-08-01

    Interest remains in reconstruction-algorithm research and development for possible improvement of image quality in current PET imaging and for enabling innovative PET systems to enhance existing, and facilitate new, preclinical and clinical applications. Optimization-based image reconstruction has been demonstrated in recent years of potential utility for CT imaging applications. In this work, we investigate tailoring the optimization-based techniques to image reconstruction for PET systems with standard and non-standard scan configurations. Specifically, given an image-total-variation (TV) constraint, we investigated how the selection of different data divergences and associated parameters impacts the optimization-based reconstruction of PET images. The reconstruction robustness was explored also with respect to different data conditions and activity up-takes of practical relevance. A study was conducted particularly for image reconstruction from data collected by use of a PET configuration with sparsely populated detectors. Overall, the study demonstrates the robustness of the TV-constrained, optimization-based reconstruction for considerably different data conditions in PET imaging, as well as its potential to enable PET configurations with reduced numbers of detectors. Insights gained in the study may be exploited for developing algorithms for PET-image reconstruction and for enabling PET-configuration design of practical usefulness in preclinical and clinical applications.

  15. Novel Fourier-based iterative reconstruction for sparse fan projection using alternating direction total variation minimization

    Science.gov (United States)

    Zhao, Jin; Han-Ming, Zhang; Bin, Yan; Lei, Li; Lin-Yuan, Wang; Ai-Long, Cai

    2016-03-01

    Sparse-view x-ray computed tomography (CT) imaging is an interesting topic in CT field and can efficiently decrease radiation dose. Compared with spatial reconstruction, a Fourier-based algorithm has advantages in reconstruction speed and memory usage. A novel Fourier-based iterative reconstruction technique that utilizes non-uniform fast Fourier transform (NUFFT) is presented in this work along with advanced total variation (TV) regularization for a fan sparse-view CT. The proposition of a selective matrix contributes to improve reconstruction quality. The new method employs the NUFFT and its adjoin to iterate back and forth between the Fourier and image space. The performance of the proposed algorithm is demonstrated through a series of digital simulations and experimental phantom studies. Results of the proposed algorithm are compared with those of existing TV-regularized techniques based on compressed sensing method, as well as basic algebraic reconstruction technique. Compared with the existing TV-regularized techniques, the proposed Fourier-based technique significantly improves convergence rate and reduces memory allocation, respectively. Projected supported by the National High Technology Research and Development Program of China (Grant No. 2012AA011603) and the National Natural Science Foundation of China (Grant No. 61372172).

  16. A novel combined regularization algorithm of total variation and Tikhonov regularization for open electrical impedance tomography.

    Science.gov (United States)

    Liu, Jinzhen; Ling, Lin; Li, Gang

    2013-07-01

    A Tikhonov regularization method in the inverse problem of electrical impedance tomography (EIT) often results in a smooth distribution reconstruction, with which we can barely make a clear separation between the inclusions and background. The recently popular total variation (TV)regularization method including the lagged diffusivity (LD) method can sharpen the edges, and is robust to noise in a small convergence region. Therefore, in this paper, we propose a novel regularization method combining the Tikhonov and LD regularization methods. Firstly, we clarify the implementation details of the Tikhonov, LD and combined methods in two-dimensional open EIT by performing the current injection and voltage measurement on one boundary of the imaging object. Next, we introduce a weighted parameter to the Tikhonov regularization method aiming to explore the effect of the weighted parameter on the resolution and quality of reconstruction images with the inclusion at different depths. Then, we analyze the performance of these algorithms with noisy data. Finally, we evaluate the effect of the current injection pattern on reconstruction quality and propose a modified current injection pattern.The results indicate that the combined regularization algorithm with stable convergence is able to improve the reconstruction quality with sharp contrast and more robust to noise in comparison to the Tikhonov and LD regularization methods solely. In addition, the results show that the current injection pattern with a bigger driver angle leads to a better reconstruction quality.

  17. Segmentation and classification of colon glands with deep convolutional neural networks and total variation regularization

    Directory of Open Access Journals (Sweden)

    Philipp Kainz

    2017-10-01

    Full Text Available Segmentation of histopathology sections is a necessary preprocessing step for digital pathology. Due to the large variability of biological tissue, machine learning techniques have shown superior performance over conventional image processing methods. Here we present our deep neural network-based approach for segmentation and classification of glands in tissue of benign and malignant colorectal cancer, which was developed to participate in the GlaS@MICCAI2015 colon gland segmentation challenge. We use two distinct deep convolutional neural networks (CNN for pixel-wise classification of Hematoxylin-Eosin stained images. While the first classifier separates glands from background, the second classifier identifies gland-separating structures. In a subsequent step, a figure-ground segmentation based on weighted total variation produces the final segmentation result by regularizing the CNN predictions. We present both quantitative and qualitative segmentation results on the recently released and publicly available Warwick-QU colon adenocarcinoma dataset associated with the GlaS@MICCAI2015 challenge and compare our approach to the simultaneously developed other approaches that participated in the same challenge. On two test sets, we demonstrate our segmentation performance and show that we achieve a tissue classification accuracy of 98% and 95%, making use of the inherent capability of our system to distinguish between benign and malignant tissue. Our results show that deep learning approaches can yield highly accurate and reproducible results for biomedical image analysis, with the potential to significantly improve the quality and speed of medical diagnoses.

  18. Mixed Total Variation and L1 Regularization Method for Optical Tomography Based on Radiative Transfer Equation

    Directory of Open Access Journals (Sweden)

    Jinping Tang

    2017-01-01

    Full Text Available Optical tomography is an emerging and important molecular imaging modality. The aim of optical tomography is to reconstruct optical properties of human tissues. In this paper, we focus on reconstructing the absorption coefficient based on the radiative transfer equation (RTE. It is an ill-posed parameter identification problem. Regularization methods have been broadly applied to reconstruct the optical coefficients, such as the total variation (TV regularization and the L1 regularization. In order to better reconstruct the piecewise constant and sparse coefficient distributions, TV and L1 norms are combined as the regularization. The forward problem is discretized with the discontinuous Galerkin method on the spatial space and the finite element method on the angular space. The minimization problem is solved by a Jacobian-based Levenberg-Marquardt type method which is equipped with a split Bregman algorithms for the L1 regularization. We use the adjoint method to compute the Jacobian matrix which dramatically improves the computation efficiency. By comparing with the other imaging reconstruction methods based on TV and L1 regularizations, the simulation results show the validity and efficiency of the proposed method.

  19. Sparse image reconstruction of targets in multilayered dielectric media using total variation minimization

    Science.gov (United States)

    Zhang, Wenji; Hoorfar, Ahmad

    2017-05-01

    In this paper, we present a sparse image reconstruction approach for radar imaging through multilayered media with total variation minimization (TVM). The approach is well suited for high-resolution imaging for both ground penetrating radar (GPR) and through-the-wall radar imaging (TWRI) applications. The multilayered media Green's function is incorporated in the imaging algorithm to efficiently model the wave propagation in the multilayered environment. For GPR imaging, the multilayered subsurface Green's function is derived in closed form with saddle point method, which is significantly less time consuming than numerical methods. For through-the-wall radar imaging, where the first and last layers are freespace, a far field approximation of the Green's function in analytical form is used to model the wave propagation through single or multilayered building walls. The TVM minimizes the gradient of the image resulting in excellent edge preservation and shape reconstruction of the image. Representative examples are presented to show high quality imaging results with limited data under various subsurface and through-the-wall imaging scenarios.

  20. Robust total-variation based geophysical inversion using split Bregman and proximity operators

    Science.gov (United States)

    Mohammadi Gheymasi, H.; Gholami, A.; Siahkoohi, H. R.; Amini, N.

    2016-09-01

    In this paper, we take advantages of split Bregman and proximity operators to formulate geophysical inverse problems in a convex optimization setting. In this type of formulation, we can efficiently consider a general convex data misfit term in order to incorporate more realistic error probability assumptions than the ordinary Gaussian distribution. Furthermore, we can simply impose convex non-quadratic and non-smooth regularization terms as a prior information. Although the proposed formulation can be extended for incorporating any types of convex regularization and data fidelity terms, here we consider misfit term corresponding to the Huber norm and anisotropic total variation regularization as a prior to an unknown model structure. This type of regularization enables us to construct piecewise-constant solutions. Two-dimensional linear and non-linear seismic travel-time tomography are studied to evaluate the efficiency of the proposed formulation for handling a robust measure of the misfit term in recovering blocky solutions. We consider the first arrival travel-times which are contaminated by outliers and also a mixed combination of Gaussian and outliers. Finally, Seinsfeld cross-hole tomography data set is used to investigate the performance of the robust approach on real data sets.

  1. A generalized accelerated proximal gradient approach for total-variation-based image restoration.

    Science.gov (United States)

    Zuo, Wangmeng; Lin, Zhouchen

    2011-10-01

    This paper proposes a generalized accelerated proximal gradient (GAPG) approach for solving total variation (TV)-based image restoration problems. The GAPG algorithm generalizes the original APG algorithm by replacing the Lipschitz constant with an appropriate positive-definite matrix, resulting in faster convergence. For TV-based image restoration problems, we further introduce two auxiliary variables that approximate the partial derivatives. Constraints on the variables can easily be imposed without modifying the algorithm much, and the TV regularization can be either isotropic or anisotropic. As compared with the recently developed APG-based methods for TV-based image restoration, i.e., monotone version of the two-step iterative shrinkage/thresholding algorithm (MTwIST) and monotone version of the fast IST algorithm (MFISTA), our GAPG is much simpler as it does not require to solve an image denoising subproblem. Moreover, the convergence rate of O(k(-2)) is maintained by our GAPG, where k is the number of iterations; the cost of each iteration in GAPG is also lower. As a result, in our experiments, our GAPG approach can be much faster than MTwIST and MFISTA. The experiments also verify that our GAPG converges faster than the original APG and MTwIST when they solve identical problems.

  2. Accelerated gradient methods for total-variation-based CT image reconstruction

    CERN Document Server

    Jørgensen, Jakob Heide; Hansen, Per Christian; Jensen, Søren Holdt; Sidky, Emil Y; Pan, Xiaochuan

    2011-01-01

    Total-variation (TV)-based Computed Tomography (CT) image reconstruction has shown experimentally to be capable of producing accurate reconstructions from sparse-view data. In particular TV-based reconstruction is very well suited for images with piecewise nearly constant regions. Computationally, however, TV-based reconstruction is much more demanding, especially for 3D imaging, and the reconstruction from clinical data sets is far from being close to real-time. This is undesirable from a clinical perspective, and thus there is an incentive to accelerate the solution of the underlying optimization problem. The TV reconstruction can in principle be found by any optimization method, but in practice the large-scale systems arising in CT image reconstruction preclude the use of memory-demanding methods such as Newton's method. The simple gradient method has much lower memory requirements, but exhibits slow convergence. In the present work we consider the use of two accelerated gradient-based methods, GPBB and UP...

  3. Spatial and temporal variation of total mercury and methylmercury in lacustrine wetland in Korea.

    Science.gov (United States)

    Kim, Moon-Kyung; Lee, Young-Min; Zoh, Kyung-Duk

    2015-05-01

    The spatial and temporal variations of total mercury (THg) and methylmercury (MeHg) concentrations (n = 120, respectively) in water and sediments of the Yangsuri lacustrine wetland in Korea were measured. The average concentrations of THg and MeHg in surface water were 2.04 ± 1.97 and 0.05 ± 0.05 ng L(-1), respectively. The concentrations of THg and MeHg in sediments ranged from 1.28 to 85.83 and ≤0.01 to 0.35 ng g(-1), respectively, and varied depending on the location. In the vegetated zone located near residential areas, the highest concentrations of THg and MeHg in both surface water and sediments were obtained near the residential areas, especially during the fall season. This result might be due to increased methylation rate of Hg by water turnover in the fall season. While THg and MeHg concentrations in water were not correlated, they were significantly correlated in sediment (r = 0.75; P levels of mercury, especially MeHg in the wetlands, and freshwater fish species in Korea.

  4. Dark channel prior based blurred image restoration method using total variation and morphology

    Institute of Scientific and Technical Information of China (English)

    Yibing Li; Qiang Fu; Fang Ye; Hayaru Shouno

    2015-01-01

    The blurred image restoration method can dramatical y highlight the image details and enhance the global contrast, which is of benefit to improvement of the visual effect during practical ap-plications. This paper is based on the dark channel prior principle and aims at the prior information absent blurred image degradation situation. A lot of improvements have been made to estimate the transmission map of blurred images. Since the dark channel prior principle can effectively restore the blurred image at the cost of a large amount of computation, the total variation (TV) and image morphology transform (specifical y top-hat transform and bottom-hat transform) have been introduced into the improved method. Compared with original transmission map estimation methods, the proposed method features both simplicity and accuracy. The es-timated transmission map together with the element can restore the image. Simulation results show that this method could inhibit the il-posed problem during image restoration, meanwhile it can greatly improve the image quality and definition.

  5. Multimodal Image Reconstruction Using Supplementary Structural Information in Total Variation Regularization.

    Science.gov (United States)

    Kazantsev, Daniil; Lionheart, William R B; Withers, Philip J; Lee, Peter D

    2014-01-01

    In this paper, we propose an iterative reconstruction algorithm which uses available information from one dataset collected using one modality to increase the resolution and signal-to-noise ratio of one collected by another modality. The method operates on the structural information only which increases its suitability across various applications. Consequently, the main aim of this method is to exploit available supplementary data within the regularization framework. The source of primary and supplementary datasets can be acquired using complementary imaging modes where different types of information are obtained (e.g. in medical imaging: anatomical and functional). It is shown by extracting structural information from the supplementary image (direction of level sets) one can enhance the resolution of the other image. Notably, the method enhances edges that are common to both images while not suppressing features that show high contrast in the primary image alone. In our iterative algorithm we use available structural information within a modified total variation penalty term. We provide numerical experiments to show the advantages and feasibility of the proposed technique in comparison to other methods.

  6. Flame slice algebraic reconstruction technique reconstruction algorithm based on radial total variation

    Science.gov (United States)

    Zhang, Shufang; Wang, Fuyao; Zhang, Cong; Xie, Hui; Wan, Minggang

    2016-09-01

    The engine flame is an important representation of the combustion process in the cylinder, and the three-dimensional (3-D) shape reconstruction of the flame can provide more information for the quantitative analysis of the flame, so as to contribute to further research on the mechanism of the combustion flame. One important method of 3-D shape reconstruction is to reconstruct the two-dimensional (2-D) projection image of the flame, so the optimization problem of the flame 2-D slice reconstruction algorithm is studied in this paper. According to the gradient sparsity characteristics in the total variation (TV) domain and radial diffusion characteristics of the engine combustion flame, a flame 2-D slice algebraic reconstruction technique (ART) reconstruction algorithm based on radial TV (ART-R-TV) is proposed. Numerical simulation results show that the new proposed ART-R-TV algorithm can reconstruct flame slice images more stably and have a better robustness than the two traditional ART algorithms especially in a limited-angle situation.

  7. Features of annual and semiannual variations derived from the global ionospheric maps of total electron content

    Directory of Open Access Journals (Sweden)

    B. Zhao

    2008-01-01

    Full Text Available In the present work we use the NASA-JPL global ionospheric maps of total electron content (TEC, firstly to construct TEC maps (TEC vs. magnetic local time MLT, and magnetic latitude MLAT in the interval from 1999 to 2005. These TEC maps were, in turn, used to estimate the annual-to-mean amplitude ratio, A1, and the semiannual-to-mean amplitude ratio, A2, as well as the latitudinal symmetrical and asymmetrical parts, A' and A" of A1. Thus, we investigated in detail the TEC climatology from maps of these indices, with an emphasis on the quantitative presentation for local time and latitudinal changes in the seasonal, annual and semiannual anomalies of the ionospheric TEC. Then we took the TEC value at 14:00 LT to examine various anomalies at a global scale following the same procedure. Results reveal similar features appearing in NmF2, such as that the seasonal anomaly is more significant in the near-pole regions than in the far-pole regions and the reverse is true for the semiannual anomaly; the winter anomaly has least a chance to be observed at the South America and South Pacific areas. The most impressive feature is that the equinoctial asymmetry is most prominent at the East Asian and South Australian areas. Through the analysis of the TIMED GUVI columnar [O/N2] data, we have investigated to what extent the seasonal, annual and semiannual variations can be explained by their counterparts in [O/N2]. Results revealed that the [O/N2] variation is a major contributor to the daytime winter anomaly of TEC, and it also contributes to some of the semiannual and annual anomalies. The contribution to the anomalies unexplained by the [O/N2] data could possibly be due to the dynamics associated with thermospheric winds and electric fields.

  8. 不同TVD格式对内孤立波数值模拟结果影响研究%Effects of TVD schemes on the numerical simulation of the internal solitary wave

    Institute of Scientific and Technical Information of China (English)

    陈同庆; 张庆河

    2013-01-01

    Based on the modified three-dimensional non-hydrostatic ocean model, SUNTANS, simulation of inter-nal solitary waves is carried out for the idealized case and the northeastern South China Sea to investigate the in-fluence of four flux limiters of TVD (total variance diminishing) scheme on the calculated results. The TVD scheme is used to solve the equations of salinity and temperature, and the considered flux limiters are superbee, minmod, van Leer, and MUSCL limiters. Analysis of the calculated results indicates that MUSCL limiter exhibits the best performance among the four considered limiters. It is recommended to use MUSCL limiter in the numerical simula-tion of internal solitary waves in the northeastern South China Sea.%  为了研究不同TVD格式对内孤立波模拟结果的影响,利用改进后的SUNTANS三维非静压海洋模型,通过理想算例和南海东北部海域内孤立波的模拟,比较分析了求解温盐方程TVD格式的4种经典通量限制函数(superbee, minmod, van Leer和MUSCL)对计算结果的影响。综合理想算例和南海东北部海域模拟结果,在所讨论的4种通量限制函数中,利用MUSCL限制函数所得模拟结果最优,建议在南海东北部海域内孤立波模拟中采用MUSCL限制函数。

  9. A promising limited angular computed tomography reconstruction via segmentation based regional enhancement and total variation minimization

    Science.gov (United States)

    Zhang, Wenkun; Zhang, Hanming; Li, Lei; Wang, Linyuan; Cai, Ailong; Li, Zhongguo; Yan, Bin

    2016-08-01

    X-ray computed tomography (CT) is a powerful and common inspection technique used for the industrial non-destructive testing. However, large-sized and heavily absorbing objects cause the formation of artifacts because of either the lack of specimen penetration in specific directions or the acquisition of data from only a limited angular range of views. Although the sparse optimization-based methods, such as the total variation (TV) minimization method, can suppress artifacts to some extent, reconstructing the images such that they converge to accurate values remains difficult because of the deficiency in continuous angular data and inconsistency in the projections. To address this problem, we use the idea of regional enhancement of the true values and suppression of the illusory artifacts outside the region to develop an efficient iterative algorithm. This algorithm is based on the combination of regional enhancement of the true values and TV minimization for the limited angular reconstruction. In this algorithm, the segmentation approach is introduced to distinguish the regions of different image knowledge and generate the support mask of the image. A new regularization term, which contains the support knowledge to enhance the true values of the image, is incorporated into the objective function. Then, the proposed optimization model is solved by variable splitting and the alternating direction method efficiently. A compensation approach is also designed to extract useful information from the initial projections and thus reduce false segmentation result and correct the segmentation support and the segmented image. The results obtained from comparing both simulation studies and real CT data set reconstructions indicate that the proposed algorithm generates a more accurate image than do the other reconstruction methods. The experimental results show that this algorithm can produce high-quality reconstructed images for the limited angular reconstruction and suppress

  10. Investigation into image quality difference between total variation and nonlinear sparsifying transform based compressed sensing

    Science.gov (United States)

    Dong, Jian; Kudo, Hiroyuki

    2017-03-01

    Compressed sensing (CS) is attracting growing concerns in sparse-view computed tomography (CT) image reconstruction. The most standard approach of CS is total variation (TV) minimization. However, images reconstructed by TV usually suffer from distortions, especially in reconstruction of practical CT images, in forms of patchy artifacts, improper serrate edges and loss of image textures. Most existing CS approaches including TV achieve image quality improvement by applying linear transforms to object image, but linear transforms usually fail to take discontinuities into account, such as edges and image textures, which is considered to be the key reason for image distortions. Actually, discussions on nonlinear filter based image processing has a long history, leading us to clarify that the nonlinear filters yield better results compared to linear filters in image processing task such as denoising. Median root prior was first utilized by Alenius as nonlinear transform in CT image reconstruction, with significant gains obtained. Subsequently, Zhang developed the application of nonlocal means-based CS. A fact is gradually becoming clear that the nonlinear transform based CS has superiority in improving image quality compared with the linear transform based CS. However, it has not been clearly concluded in any previous paper within the scope of our knowledge. In this work, we investigated the image quality differences between the conventional TV minimization and nonlinear sparsifying transform based CS, as well as image quality differences among different nonlinear sparisying transform based CSs in sparse-view CT image reconstruction. Additionally, we accelerated the implementation of nonlinear sparsifying transform based CS algorithm.

  11. Cerebral perfusion computed tomography deconvolution via structure tensor total variation regularization

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Dong; Zhang, Xinyu; Bian, Zhaoying, E-mail: zybian@smu.edu.cn, E-mail: jhma@smu.edu.cn; Huang, Jing; Zhang, Hua; Lu, Lijun; Lyu, Wenbing; Feng, Qianjin; Chen, Wufan; Ma, Jianhua, E-mail: zybian@smu.edu.cn, E-mail: jhma@smu.edu.cn [Department of Biomedical Engineering, Southern Medical University, Guangzhou, Guangdong 510515, China and Guangdong Provincial Key Laboratory of Medical Image Processing, Southern Medical University, Guangzhou, Guangdong 510515 (China); Zhang, Jing [Department of Radiology, Tianjin Medical University General Hospital, Tianjin 300052 (China)

    2016-05-15

    Purpose: Cerebral perfusion computed tomography (PCT) imaging as an accurate and fast acute ischemic stroke examination has been widely used in clinic. Meanwhile, a major drawback of PCT imaging is the high radiation dose due to its dynamic scan protocol. The purpose of this work is to develop a robust perfusion deconvolution approach via structure tensor total variation (STV) regularization (PD-STV) for estimating an accurate residue function in PCT imaging with the low-milliampere-seconds (low-mAs) data acquisition. Methods: Besides modeling the spatio-temporal structure information of PCT data, the STV regularization of the present PD-STV approach can utilize the higher order derivatives of the residue function to enhance denoising performance. To minimize the objective function, the authors propose an effective iterative algorithm with a shrinkage/thresholding scheme. A simulation study on a digital brain perfusion phantom and a clinical study on an old infarction patient were conducted to validate and evaluate the performance of the present PD-STV approach. Results: In the digital phantom study, visual inspection and quantitative metrics (i.e., the normalized mean square error, the peak signal-to-noise ratio, and the universal quality index) assessments demonstrated that the PD-STV approach outperformed other existing approaches in terms of the performance of noise-induced artifacts reduction and accurate perfusion hemodynamic maps (PHM) estimation. In the patient data study, the present PD-STV approach could yield accurate PHM estimation with several noticeable gains over other existing approaches in terms of visual inspection and correlation analysis. Conclusions: This study demonstrated the feasibility and efficacy of the present PD-STV approach in utilizing STV regularization to improve the accuracy of residue function estimation of cerebral PCT imaging in the case of low-mAs.

  12. Accelerated gradient methods for total-variation-based CT image reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Joergensen, Jakob H.; Hansen, Per Christian [Technical Univ. of Denmark, Lyngby (Denmark). Dept. of Informatics and Mathematical Modeling; Jensen, Tobias L.; Jensen, Soeren H. [Aalborg Univ. (Denmark). Dept. of Electronic Systems; Sidky, Emil Y.; Pan, Xiaochuan [Chicago Univ., Chicago, IL (United States). Dept. of Radiology

    2011-07-01

    Total-variation (TV)-based CT image reconstruction has shown experimentally to be capable of producing accurate reconstructions from sparse-view data. In particular TV-based reconstruction is well suited for images with piecewise nearly constant regions. Computationally, however, TV-based reconstruction is demanding, especially for 3D imaging, and the reconstruction from clinical data sets is far from being close to real-time. This is undesirable from a clinical perspective, and thus there is an incentive to accelerate the solution of the underlying optimization problem. The TV reconstruction can in principle be found by any optimization method, but in practice the large scale of the systems arising in CT image reconstruction preclude the use of memory-intensive methods such as Newton's method. The simple gradient method has much lower memory requirements, but exhibits prohibitively slow convergence. In the present work we address the question of how to reduce the number of gradient method iterations needed to achieve a high-accuracy TV reconstruction. We consider the use of two accelerated gradient-based methods, GPBB and UPN, to solve the 3D-TV minimization problem in CT image reconstruction. The former incorporates several heuristics from the optimization literature such as Barzilai-Borwein (BB) step size selection and nonmonotone line search. The latter uses a cleverly chosen sequence of auxiliary points to achieve a better convergence rate. The methods are memory efficient and equipped with a stopping criterion to ensure that the TV reconstruction has indeed been found. An implementation of the methods (in C with interface to Matlab) is available for download from http://www2.imm.dtu.dk/~pch/TVReg/. We compare the proposed methods with the standard gradient method, applied to a 3D test problem with synthetic few-view data. We find experimentally that for realistic parameters the proposed methods significantly outperform the standard gradient method. (orig.)

  13. Landscape drivers of regional variation in the relationship between total phosphorus and chlorophyll in lakes

    Science.gov (United States)

    Wagner, T.; Soranno, P.A.; Webster, K.E.; Cheruvelil, K.S.

    2011-01-01

    For north temperate lakes, the well-studied empirical relationship between phosphorus (as measured by total phosphorus, TP), the most commonly limiting nutrient and algal biomass (as measured by chlorophyll a, CHL) has been found to vary across a wide range of landscape settings. Variation in the parameters of these TP-CHL regressions has been attributed to such lake variables as nitrogen/phosphorus ratios, organic carbon and alkalinity, all of which are strongly related to catchment characteristics (e.g. natural land cover and human land use). Although this suggests that landscape setting can help to explain much of the variation in ecoregional TP-CHL regression parameters, few studies have attempted to quantify relationships at an ecoregional spatial scale. We tested the hypothesis that lake algal biomass and its predicted response to changes in phosphorus are related to both local-scale features (e.g. lake and catchment) and ecoregional-scale features, all of which affect the availability and transport of covarying solutes such as nitrogen, organic carbon and alkalinity. Specifically, we expected that land use and cover, acting at both local and ecoregional scales, would partially explain the spatial pattern in parameters of the TP-CHL regression. We used a multilevel modelling framework and data from 2105 inland lakes spanning 35 ecoregions in six US states to test our hypothesis and identify specific local and ecoregional features that explain spatial heterogeneity in TP-CHL relationships. We include variables such as lake depth, natural land cover (for instance, wetland cover in the catchment of lakes and in the ecoregions) and human land use (for instance, agricultural land use in the catchment of lakes and in the ecoregions). There was substantial heterogeneity in TP-CHL relationships across the 35 ecoregions. At the local scale, CHL was negatively and positively related to lake mean depth and percentage of wooded wetlands in the catchment, respectively. At

  14. Variation in the cost of care for primary total knee arthroplasties

    Directory of Open Access Journals (Sweden)

    Derek A. Haas, MBA

    2017-03-01

    Conclusions: The large variation in costs among sites suggests major and multiple opportunities to transfer knowledge about process and productivity improvements that lower costs while simultaneously maintaining or improving outcomes.

  15. Testable uniqueness conditions for empirical assessment of undersampling levels in total variation-regularized X-ray CT

    DEFF Research Database (Denmark)

    Jørgensen, Jakob Sauer; Kruschel, C.; Lorenz, D. A.

    2015-01-01

    We study recoverability in fan-beam computed tomography (CT) with sparsity and total variation priors: how many underdetermined linear measurements suffice for recovering images of given sparsity? Results from compressed sensing (CS) establish such conditions for example for random measurements...

  16. A Banach algebra of functions of several variables of finite total variation and Lipschitzian superposition operators. I

    NARCIS (Netherlands)

    Chistyakov, VV

    2005-01-01

    It is shown that the space of functions of n real variables with finite total variation in the sense of Vitali, Hardy and Krause, defined on a rectangle I-a(b) C R-n, is a Banach algebra under the pointwise operations and Hildebrandt-Leonov's norm. This result generalizes the classical case of funct

  17. The imprint of surface fluxes and transport on variations in total column carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Keppel-Aleks, G [California Institute of Technology, Pasadena; Wennberg, PO [California Institute of Technology, Pasadena; Washenfelder, RA [National Oceanic and Atmospheric Admin; Wunch, D [California Institute of Technology, Pasadena; Schneider, T [California Institute of Technology, Pasadena; Toon, GC [Jet Propulsion Laboratory, Pasadena, CA; Andres, Robert Joseph [ORNL; Blavier, J-F [Jet Propulsion Laboratory, Pasadena, CA; Connor, B [BC Consulting; Davis, K. J. [Pennsylvania State University; Desai, Desai Ankur R. [University of Wisconsin, Madison; Messerschmidt, J [University of Bremen, Bremen, Germany; Notholt, J [University of Bremen, Bremen, Germany; Roehl, CM [California Institute of Technology, Pasadena; Sherlock, V [National Institue of Water and Atmospheric Research, New Zealand; Stephens, BB [National Center for Atmospheric Research (NCAR); Vay, SA [NASA Langley Research Center; Wofsy, Steve [Harvard University

    2012-01-01

    New observations of the vertically integrated CO{sub 2} mixing ratio, , from ground-based remote sensing show that variations in are primarily determined by large-scale flux patterns. They therefore provide fundamentally different information than observations made within the boundary layer, which reflect the combined influence of large-scale and local fluxes. Observations of both and CO{sub 2} concentrations in the free troposphere show that large-scale spatial gradients induce synoptic-scale temporal variations in in the Northern Hemisphere midlatitudes through horizontal advection. Rather than obscure the signature of surface fluxes on atmospheric CO{sub 2}, these synoptic-scale variations provide useful information that can be used to reveal the meridional flux distribution. We estimate the meridional gradient in from covariations in and potential temperature, {theta}, a dynamical tracer, on synoptic timescales to evaluate surface flux estimates commonly used in carbon cycle models. We find that simulations using Carnegie Ames Stanford Approach (CASA) biospheric fluxes underestimate both the seasonal cycle amplitude throughout the Northern Hemisphere midlatitudes and the meridional gradient during the growing season. Simulations using CASA net ecosystem exchange (NEE) with increased and phase-shifted boreal fluxes better fit the observations. Our simulations suggest that climatological mean CASA fluxes underestimate boreal growing season NEE (between 45-65{sup o} N) by {approx}40%. We describe the implications for this large seasonal exchange on inference of the net Northern Hemisphere terrestrial carbon sink.

  18. Monte Carlo estimation of total variation distance of Markov chains on large spaces, with application to phylogenetics.

    Science.gov (United States)

    Herbei, Radu; Kubatko, Laura

    2013-03-26

    Markov chains are widely used for modeling in many areas of molecular biology and genetics. As the complexity of such models advances, it becomes increasingly important to assess the rate at which a Markov chain converges to its stationary distribution in order to carry out accurate inference. A common measure of convergence to the stationary distribution is the total variation distance, but this measure can be difficult to compute when the state space of the chain is large. We propose a Monte Carlo method to estimate the total variation distance that can be applied in this situation, and we demonstrate how the method can be efficiently implemented by taking advantage of GPU computing techniques. We apply the method to two Markov chains on the space of phylogenetic trees, and discuss the implications of our findings for the development of algorithms for phylogenetic inference.

  19. Diurnal variation in total plasma tryptophan in controls and in depression.

    Science.gov (United States)

    Candito, M; Souêtre, E; Iordache, A; Pringuey, D; Ardisson, J L; Chambon, P; Darcourt, G

    1990-01-01

    Circadian rhythms of total tryptophan were investigated by assays of hourly blood samples over 25 h. The study population consisted of four endogenously depressed patients investigated in the absence of any treatment and six healthy controls. The abnormalities detected by statistical analyses in untreated depression consisted mainly of amplitude reduction; the phase positions of the depressed patients were similar to those of the controls.

  20. Geographical variation in total and inorganic arsenic content of polished (white) rice.

    Science.gov (United States)

    Meharg, Andrew A; Williams, Paul N; Adomako, Eureka; Lawgali, Youssef Y; Deacon, Claire; Villada, Antia; Cambell, Robert C J; Sun, Guoxin; Zhu, Yong-Guan; Feldmann, Joerg; Raab, Andrea; Zhao, Fang-Jie; Islam, Rafiqul; Hossain, Shahid; Yanai, Junta

    2009-03-01

    An extensive data set of total arsenic analysis for 901 polished (white) grain samples, originating from 10 countries from 4 continents, was compiled. The samples represented the baseline (i.e., notspecifically collected from arsenic contaminated areas), and all were for market sale in major conurbations. Median total arsenic contents of rice varied 7-fold, with Egypt (0.04 mg/kg) and India (0.07 mg/kg) having the lowest arsenic content while the U.S. (0.25 mg/kg) and France (0.28 mg/kg) had the highest content. Global distribution of total arsenic in rice was modeled by weighting each country's arsenic distribution by that country's contribution to global production. A subset of 63 samples from Bangladesh, China, India, Italy, and the U.S. was analyzed for arsenic species. The relationship between inorganic arsenic contentversus total arsenic contentsignificantly differed among countries, with Bangladesh and India having the steepest slope in linear regression, and the U.S. having the shallowest slope. Using country-specific rice consumption data, daily intake of inorganic arsenic was estimated and the associated internal cancer risk was calculated using the U.S. Environmental Protection Agency (EPA) cancer slope. Median excess internal cancer risks posed by inorganic arsenic ranged 30-fold for the 5 countries examined, being 0.7 per 10,000 for Italians to 22 per 10,000 for Bangladeshis, when a 60 kg person was considered.

  1. Variation Dynamics of Total Nitrogen and Nicotine of Burley Tobacco at Various Growing Stages under Different Nitrogen Nutrition Levels

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    [Objective] This study aimed to investigate the variation dynamics of total nitrogen and nicotine of burtey tobacco at various growing stages under different ni- trogen nutrition levels to provide reference for optimizing fertilization technologies for burley tobacco. [Method] Fresh burley tobacco leaves were collected at various growing stages and dried to measure the content of total nitrogen, protein and nico- tine by using INTEGRAL automated chemical analyzer and analyze the correlation with nitrogen application level. [Result] Regardless of the nitrogen application level, the content of total nitrogen and protein showed a downward trend since root ex- tending stage and reached the minimum at mature stage; the content of nicotine showed an upward trend since early vigorous growing stage and increased to the maximum at mature stage; the content of total nitrogen, protein and nicotine all in- creased after air curing; the content of total nitrogen, protein and nicotine showed positive correlation with nitrogen application level, while total nitrogen/nicotine was negatively correlated. The results indicate that nitrogen level is closely related to the total nitrogen and nicotine of burley tobacco at growing period and post-air curing, rational application of nitrogen is an important measure to regulate the content of total nitrogen and nicotine of tobacco. [Conclusion] This study provides scientific ba- sis for rational fertilization of burley tobacco.

  2. Content Variation of Catechin Markers, Total Phenolics and Caffeine in Green Tea Dietary Supplements.

    Science.gov (United States)

    Abourashed, Ehab A; Roberson, Cindy Leslie A; Elsharkawy, Nancy

    2016-01-01

    Green tea (Camellia sinensis) preparations are among the top selling products in the United States dietary supplements market. Numerous manufacturers claim different levels of specific catechin markers in their products while many others use total phenolic concentration instead, or not at all. Limited quality control results have been published for green tea dietary supplements over the past seven years. Thus, the goal of this work was to correlate determined levels of phenolics, catechins, and caffeine with manufacturer label claims for selected dietary supplement products (26 total) purchased in the United States. The Folin-Ciocalteu (FC) method was used to determine the total phenolic content while reversed-phase (RP) HPLC was used to quantify the major catechins: epicatechin (EC), epigallocatechin (EGC), epicatechin gallate (ECG), epigallocatechin gallate (EGCG). The developed HPLC method was validated for accuracy and precision. It utilized a C8 column with gradient elution of acetonitrile in 0.1% aqueous formic acid over 11 min total run time. Peak detection was performed at 280 nm. Caffeine was also included in the HPLC method as another non-phenolic alkaloid marker commonly found in green tea. Both methods showed a good correlation between the content of catechins and polyphenolic compounds in the selected products. The ranges of total catechins and polyphenol concentrations were 3.8-70.2% and 3.6-95.8%, respectively, while that of caffeine was 0.8-11.2%. The selected products displayed a wide range of marker levels. A lack of conformity in disclosing the actual levels of marker compounds was also noticed in the labeling of many products.

  3. Studies of Total Electron Content variations at low-latitude stations within the Equatorial Ionization Anomaly zone

    Science.gov (United States)

    Lilian, Olatunbosun

    2016-07-01

    The total electron content (TEC) is an important parameter to monitor for possible space weather impacts. The radio waves that pass through the earth's ionosphere travel more slowly than their free space velocity due to group path delay of the ionosphere. This group path delay is directly proportional to the TEC of the ionosphere. Using dual frequency GPS receiver at low latitude stations of Ile-Ife (7.52oN, 4.28oE), Addis Ababa (9.04oN, 38.77oE) and Bangalore (13.03oE, 77.57oE), all located within 0 - 15oN of the equatorial anomaly region, the measurement of ionospheric TEC for 2012 has been carried out. The data from the three stations were used to study the diurnal, monthly and seasonal variations of TEC. The diurnal variations maximize between 10:00 - 16:00UT, 08:00 - 14:00UT and 06:00 - 12:00UT for Ile-Ife, Addis Ababa and Bangalore stations respectively. The diurnal variations showed wave-like pertubation during disturbed and quiet periods at Bangalore and Addis Ababa stations. The monthly average TEC variations showed that the month of March recorded the highest TEC value of ~59TECu at about 16:00UT in Ile-Ife station, while TEC at Addis Ababa and Bangalore maximize in October with ~72TECu and 65TECu at about 11:00UT and 09:00UT respectively. Seasonal variations showed that TEC maximizes during the equinoctial months and least in summer, over the three stations. Keywords: Total Electron Content, Equatorial Ionization Anomaly, Global Positioning System co-author:E.A. Ariyibi(Department of Physics and Engineering Physics, Obafemi Awolowo University, Ile-Ife, Nigeria)

  4. Variations of the 'grand-piano sign' during total knee replacement. A computer-simulation study.

    Science.gov (United States)

    Cui, W-Q; Won, Y-Y; Baek, M-H; Kim, K-K; Cho, J-H

    2006-11-01

    The appearance of the 'grand-piano sign' on the anterior resected surface of the femur has been considered to be a marker for correct femoral rotational alignment during total knee replacement. Our study was undertaken to assess quantitatively the morphological patterns on the resected surface after anterior femoral resection with various angles of external rotation, using a computer-simulation technique. A total of 50 right distal femora with varus osteoarthritis in 50 Korean patients were scanned using computerised tomography. Computer image software was used to simulate the anterior femoral cut, which was applied at an external rotation of 0 degrees, 3 degrees and 6 degrees relative to the posterior condylar axis, and parallel to the surgical and clinical epicondylar axes in each case. The morphological patterns on the resected surface were quantified and classified as the 'grand-piano sign', 'the boot sign' and the 'butterfly sign'. The surgeon can use the analogy of these quantified sign patterns to ensure that a correct rotational alignment has been obtained intra-operatively.

  5. Variation with Mach Number of Static and Total Pressures Through Various Screens

    Science.gov (United States)

    Adler, Alfred A

    1946-01-01

    Tests were conducted in the Langley 24-inch highspeed tunnel to ascertain the static-pressure and total-pressure losses through screens ranging in mesh from 3 to 12 wires per inch and in wire diameter from 0.023 to 0.041 inch. Data were obtained from a Mach number of approximately 0.20 up to the maximum (choking) Mach number obtainable for each screen. The results of this investigation indicate that the pressure losses increase with increasing Mach number until the choking Mach number, which can be computed, is reached. Since choking imposes a restriction on the mass rate of flow and maximum losses are incurred at this condition, great care must be taken in selecting the screen mesh and wire dimmeter for an installation so that the choking Mach number is

  6. Penalized weighted least-squares approach for multienergy computed tomography image reconstruction via structure tensor total variation regularization.

    Science.gov (United States)

    Zeng, Dong; Gao, Yuanyuan; Huang, Jing; Bian, Zhaoying; Zhang, Hua; Lu, Lijun; Ma, Jianhua

    2016-10-01

    Multienergy computed tomography (MECT) allows identifying and differentiating different materials through simultaneous capture of multiple sets of energy-selective data belonging to specific energy windows. However, because sufficient photon counts are not available in each energy window compared with that in the whole energy window, the MECT images reconstructed by the analytical approach often suffer from poor signal-to-noise and strong streak artifacts. To address the particular challenge, this work presents a penalized weighted least-squares (PWLS) scheme by incorporating the new concept of structure tensor total variation (STV) regularization, which is henceforth referred to as 'PWLS-STV' for simplicity. Specifically, the STV regularization is derived by penalizing higher-order derivatives of the desired MECT images. Thus it could provide more robust measures of image variation, which can eliminate the patchy artifacts often observed in total variation (TV) regularization. Subsequently, an alternating optimization algorithm was adopted to minimize the objective function. Extensive experiments with a digital XCAT phantom and meat specimen clearly demonstrate that the present PWLS-STV algorithm can achieve more gains than the existing TV-based algorithms and the conventional filtered backpeojection (FBP) algorithm in terms of both quantitative and visual quality evaluations.

  7. Variations of total electron content in the equatorial anomaly region in Thailand

    Science.gov (United States)

    Chowdhary, V. Rajesh; Tripathi, N. K.; Arunpold, Sanit; Raju, Durairaju Kumaran

    2015-01-01

    This paper presents the first results of total electron content (TEC), derived by analyzing dual frequency Novatel GSV4004 GPS receiver's data which were installed by the SCINDA project, located at the Asian Institute of Technology, Bangkok (AITB, 14.079N, 100.612E) and Chiang Mai University, Chiang Mai (CHGM, 18.480N, 98.570E) with magnetic latitude of 4.13°N and 8.61°N respectively in Thailand, for the year 2011. These two stations are separated by 657 km in the equatorial anomaly region. The highest TEC values occurred from 1500 to 1900 LT throughout the study period. The diurnal, monthly and seasonal GPS-TEC have been plotted and analyzed. The diurnal peaks in GPS-TEC is observed to be maximum during equinoctial months (March, April, September and October) and minimum in solstice months (January, February, June, July and December). These high TEC values have been attributed to the solar extreme ultra-violet ionization coupled with the upward vertical E × B drift. A comparison of both station's TEC has been carried out and found that CHGM station experiences higher values of TEC than AITB station, due to formation of ionization crest over the CHGM station. Also, TEC values have shown increasing trend due to approaching solar maximum. These results from both stations were also compared with the TEC derived from the International Reference Ionosphere's (IRI) recently released, IRI-2012 model. Results have shown positive correlation with IRI-2012 model. Although, IRI-model does not show any response to geomagnetic activity, the IRI model normally remains smooth and underestimates TEC during a storm.

  8. Factors influencing variation of bulk milk antibiotic residue occurrence, somatic cell count, and total bacterial count in dairy sheep flocks.

    Science.gov (United States)

    Gonzalo, C; Carriedo, J A; García-Jimeno, M C; Pérez-Bilbao, M; de la Fuente, L F

    2010-04-01

    To study the variations of bulk tank milk variables in dairy ewe flocks and to identify the main target practices and flock groups to improve milk quality and safety, a total of 71,228 records of antibiotic residue (AR) and milk yield and 68,781 records of somatic cell count (SCC) and total bacterial count (TBC) were obtained over 5 yr from the same 209 dairy ewe flocks of the Assaf breed belonging to the Consortium for Ovine Promotion of Castilla-León (Spain). Based on a logistic regression model, year, month, semester, SCC, TBC, dry therapy, and milk yield significantly contributed to AR variation. High SCC was associated with increased AR violations. When antibiotic dry therapy was implemented, AR occurrence was higher than when this practice was not used. A polynomial monthly distribution throughout the year was observed for AR occurrence; the highest values were in autumn, coinciding with low milk yields per flock. Yearly occurrences drastically diminished from 2004 (1.36%) to 2008 (0.30%), probably as a result of effective educational programs. The mixed-model ANOVA of factors influencing variation in SCC and TBC indicated that year, month, AR, dry therapy group, milking type, and year interactions were significant variation factors for SCC and TBC; mathematical model accounted for 74.1 and 35.4% of total variance for each variable, respectively. Differences in management and hygiene practice caused significant SCC and TBC variations among flocks and within flocks throughout the 5-yr study. Over time, continuously dry treated flocks showed lower logSCC (5.80) and logTBC (4.92) than untreated (6.10 and 5.18, respectively) or discontinuously dry treated (6.01 and 5.05, respectively) flocks. Continuously dry treated flocks had lower AR occurrences than did discontinuously dry treated flocks. As a whole, AR occurrence and SCC and TBC bulk tank milk variables can be used for monitoring mammary health and milk hygiene and safety in dairy sheep throughout time.

  9. 非局部的变分正则化图像放大算法%Variational image zooming based on nonlocal total variation

    Institute of Scientific and Technical Information of China (English)

    姜东焕; 徐光宝; 东野长磊

    2012-01-01

    A regularized image zooming model based on nonlocal total variation was proposed, with regard to that the Chambolle image zooming model has blocky effects. It consisted of regular term and fidelity term. The zoomed image was obtained by minimizing the variational function which used the nonlocal total variation norm to measure the regularity of the image. Unlike the traditional image zooming by interpolation, the variational model was incorporated in the new zooming algorithm and the use of nonlocal operator made the algorithm not just use a single pixel of the image, or gray and gradient information in a neighborhood to amplify, but use the information of image content itself widely that will avoid blocky effects of Chambolle's model. The experimental results show that the new algorithm can preserve better the border and details. It achieves better effect than Chambolle's method and the interpolation by using spline.%针对Chambolle图像放大模型存在分块效应,提出一种非局部的变分正则化图像放大算法.该算法的思想是构造一个适用于图像放大的变分泛函,该泛函由正则项和数据保真项构成,其中图像的正则项是用非局部全变差范数进行估计,进而用迭代投影方法求泛函的最小解,即为放大后的图像.与传统的图像插值方法不同,该算法是用变分的思想进行图像放大,非局部全变差的引入更使得该算法不只是利用图像的单个像素点,或某一邻域内的灰度和梯度信息进行放大,而是更大范围地利用了图像本身的信息,这将更有效地保留图像特征,避免了Chambolle方法在图像放大时出现的分块效应.实验结果表明,该算法能更好地保留边缘和细节信息,放大图像的清晰度比Chambolle图像放大方法和样条插值的效果要好.

  10. Robust joint full-waveform inversion of time-lapse seismic data sets with total-variation regularization

    CERN Document Server

    Maharramov, Musa

    2014-01-01

    We present a technique for reconstructing subsurface velocity model changes from time-lapse seismic survey data using full-waveform inversion (FWI). The technique is based on simultaneously inverting multiple survey vintages, with model difference regularization using the total variation (TV) seminorm. We compare the new TV-regularized time-lapse FWI with the $L_2$-regularized joint inversion proposed in our earlier work, using synthetic data sets that exhibit survey repeatability issues. The results demonstrate clear advantages of the proposed TV-regularized joint inversion over alternatives methods for recovering production-induced model changes that are due to both fluid substitution and geomechanical effects.

  11. Utilization of 100 mb midlatitude height fields as an indicator of sampling effects on total ozone variations

    Science.gov (United States)

    Miller, A. J.; Nagatani, R. M.; Laver, J. D.; Korty, B.

    1979-01-01

    Midlatitude 100-mb height fields are employed to determine the effects of ground based sampling locations on measurements of variations in the total ozone content of the atmosphere. The precision of the zonal average heights computed by the technique of Angell and Korshover (1978) from data over ozone sampling areas at 50 deg N is compared to the zonal average computed from the entire data set. Linear regressions of ozone contents determined by an analysis of backscatter UV satellite data with respect to 100 mb heights are utilized to transform zonal differences in height to ozone levels. The zonal average total ozone sampling error is found to be on the order of 2% for midlatitudes of the Northern hemisphere, indicating that the general shape of ozone trends determined by ground-based observations appears to be real and the increase of ozone from the mid-1960's to the early 1970's may be greater than previously suggested.

  12. Variaciones de la técnica convencional de histerectomía total abdominal Variations of the conventional technique of total abdominal hysterectomy

    Directory of Open Access Journals (Sweden)

    Bárbaro Agustín Armas Pérez

    2008-12-01

    and the ligature of the vascular pedicles. METHODS. A descriptive study was undertaken aimed at exposing the modifications introduced in the traditional technique of Richardson's total abdominal hysterectomy in 155 female patients operated on at «Amalia Simoni» Clinical and Surgical Teaching Hospital (Camagüey from 2002 to 2007. The primary source of information was a survey, and the data collected were processed by automated means through the Microstat statistical package. RESULTS. Average age was 42.35 years old. The most used anesthesia was the regional spinal (75.48 %. The mean surgical time was 56.15 minutes, whereas postoperative complications accounted for 7.74 %. Hemorrhages (3.23 % and infections (2.58 %. were among the most frequent. No case was reoperated on and excellent results were attained as regards aesthetics, reduction of surgical time, decrease of postoperative pain and hospital stay. CONCLUSIONS.The complications found were not related to the variations of the technique applied. The operations were less painful and more aesthetic than the conventional ones.

  13. Research of Ionospheric Total Electron Content Variations Caused by Powerful Radio Emission of `SURA' Facility on Network of Gnss - Receivers

    Science.gov (United States)

    Kogogin, Denis; Nasyrov, Igor; Grach, Savely; Shindin, Alexey; Zagretdinov, Renat; Shaimukhametov, Ramil; Kislichin, Alexander; Ryabova, Mariya

    Large-scale irregularities with scales of 5-50 km can be effectively studied using dual-frequency raying by signals of the Navstar (GPS) and GLONASS microwave satellite systems. During propagation through the heated region, such signals acquire an additional phase increment stipulated by the dispersion of radio waves in the ionospheric plasma and linearly related to the total electron content (TEC) on the propagation trajectory. In this work we present results of measurement of total electron content (TEC) variations in the F2 part of the ionosphere of the Earth caused by powerful radio emission of “Sura” facility carried out during several experimental companies from 2010 to 2013 years. Parameters of TEC-variations were obtained by dual - frequency global navigation satellite systems (GNSS) diagnostics. Registration of signal parameters from GNSS-transmitters was performed at spatially separated sites around the “Sura” facility: Vasilsursk (56(°) 08' N, 46(°) 05' E), Zelenodolsk (55(°) 52' N, 48(°) 33' E), Kazan (55(°) 48' N, 49(°) 08' E) and Yoshkar-Ola (56(°) 38'N, 47(°) 52'E). The initial data containing measurements of the phase L and pseudorange P for the operating frequencies f1 =1575.42 MHz and f2 = 1227.60 MHz are RINEX files. For a detail study of small TEC variations based on the initial dependence, the trend was removed by subtraction of the moving average with the use of the linear weight function. In the experiments radio path from GNSS satellite to Vasilsursk passed over the disturbed region of ionosphere, but radio paths to Zelenodolsk, to Kazan and to Yoshkar-Ola did not. However, TEC-variations correlated with pumping of ionosphere by ”Sura” facility were detected for three ground measurements sites, situated along the “Sura” facility geomagnetic longitude (Vasilsursk, Zelenodolsk, Kazan). Magnitudes of TEC-variations reached 0.15-0.3 TECU. Velocity of propagation of large-scale ionospheric disturbance stimulated by

  14. Joint reconstruction of dynamic PET activity and kinetic parametric images using total variation constrained dictionary sparse coding

    Science.gov (United States)

    Yu, Haiqing; Chen, Shuhang; Chen, Yunmei; Liu, Huafeng

    2017-05-01

    Dynamic positron emission tomography (PET) is capable of providing both spatial and temporal information of radio tracers in vivo. In this paper, we present a novel joint estimation framework to reconstruct temporal sequences of dynamic PET images and the coefficients characterizing the system impulse response function, from which the associated parametric images of the system macro parameters for tracer kinetics can be estimated. The proposed algorithm, which combines statistical data measurement and tracer kinetic models, integrates a dictionary sparse coding (DSC) into a total variational minimization based algorithm for simultaneous reconstruction of the activity distribution and parametric map from measured emission sinograms. DSC, based on the compartmental theory, provides biologically meaningful regularization, and total variation regularization is incorporated to provide edge-preserving guidance. We rely on techniques from minimization algorithms (the alternating direction method of multipliers) to first generate the estimated activity distributions with sub-optimal kinetic parameter estimates, and then recover the parametric maps given these activity estimates. These coupled iterative steps are repeated as necessary until convergence. Experiments with synthetic, Monte Carlo generated data, and real patient data have been conducted, and the results are very promising.

  15. Efficient and robust 3D CT image reconstruction based on total generalized variation regularization using the alternating direction method.

    Science.gov (United States)

    Chen, Jianlin; Wang, Linyuan; Yan, Bin; Zhang, Hanming; Cheng, Genyang

    2015-01-01

    Iterative reconstruction algorithms for computed tomography (CT) through total variation regularization based on piecewise constant assumption can produce accurate, robust, and stable results. Nonetheless, this approach is often subject to staircase artefacts and the loss of fine details. To overcome these shortcomings, we introduce a family of novel image regularization penalties called total generalized variation (TGV) for the effective production of high-quality images from incomplete or noisy projection data for 3D reconstruction. We propose a new, fast alternating direction minimization algorithm to solve CT image reconstruction problems through TGV regularization. Based on the theory of sparse-view image reconstruction and the framework of augmented Lagrange function method, the TGV regularization term has been introduced in the computed tomography and is transformed into three independent variables of the optimization problem by introducing auxiliary variables. This new algorithm applies a local linearization and proximity technique to make the FFT-based calculation of the analytical solutions in the frequency domain feasible, thereby significantly reducing the complexity of the algorithm. Experiments with various 3D datasets corresponding to incomplete projection data demonstrate the advantage of our proposed algorithm in terms of preserving fine details and overcoming the staircase effect. The computation cost also suggests that the proposed algorithm is applicable to and is effective for CBCT imaging. Theoretical and technical optimization should be investigated carefully in terms of both computation efficiency and high resolution of this algorithm in application-oriented research.

  16. Quantitative Monitoring for Enhanced Geothermal Systems Using Double-Difference Waveform Inversion with Spatially-Variant Total-Variation Regularization

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Youzuo [Los Alamos National Laboratory; Huang, Lianjie [Los Alamos National Laboratory; Zhang, Zhigang [Los Alamos National Laboratory

    2011-01-01

    Double-difference waveform inversion is a promising tool for quantitative monitoring for enhanced geothermal systems (EGS). The method uses time-lapse seismic data to jointly inverts for reservoir changes. Due to the ill-posedness of waveform inversion, it is a great challenge to obtain reservoir changes accurately and efficiently, particularly when using timelapse seismic reflection data. To improve reconstruction, we develop a spatially-variant total-variation regularization scheme into double-difference waveform inversion to improve the inversion accuracy and robustness. The new regularization scheme employs different regularization parameters in different regions of the model to obtain an optimal regularization in each area. We compare the results obtained using a spatially-variant parameter with those obtained using a constant regularization parameter. Utilizing a spatially-variant regularization scheme, the target monitoring regions are well reconstructed and the image noise is significantly reduced outside the monitoring regions. Our numerical examples demonstrate that the spatially-variant total-variation regularization scheme provides the flexibility to regularize local regions based on the a priori spatial information without increasing computational costs and the computer memory requirement.

  17. Relative amplitude of the variations of the total electron content according to the data of the GPS global network

    Science.gov (United States)

    Perevalova, N. P.; Afraimovich, E. L.; Zhivetiev, I. V.; Kosogorov, E. A.

    2007-04-01

    [1] A method is developed that makes it possible to estimate the relative amplitude dI/I of the variations of the total electron content (TEC) corresponding to the mean (MS) and intermediate (IS) scales of ionospheric irregularities (from 300 to 30 km). This method is based on the evaluation of TEC variations from the data of the global GPS network. The results of the analysis of the diurnal and latitudinal dependencies of dI/I and distribution probability P(dI/I) for 52 days with different level of geomagnetic activity are presented. The statistical estimates were obtained from the analysis of 106 samples of 2-hour-long TEC series. To obtain statistically significant results, we have chosen three latitudinal zones provided on the Web by the maximum number of GPS sites: high-latitudinal zone of the Northern America (50-80o N, 200-300o E; 59 stations), midlatitude zone of the Northern America (20-50o N, 200-300o E; 817 stations), and the equatorial zone (20o S-20o N, 0-360o E; 76 stations). It was found that on the average the relative amplitude of the TEC variations varies within the range 0-10% proportionally to the value of the Kp geomagnetic index. This dependence is best pronounced at high latitudes (the proportionality coefficient k = 0.37), is weaker at middle latitudes (k = 0.2), and is the weakest at the equator (kcardinal depletion of the slope of the power spectrum of TEC disturbances because of a decrease of the amplitude of the small-scale parts of the spectrum. The amplitude of TEC variations almost does not depend on solar activity index F 10.7. The obtained results do not always agree with the known mechanisms of generation and propagation of ionospheric irregularities at various latitudes and may be useful for development of the theory.

  18. Standardization of total cholesterol measurement in population surveys--pre-analytic sources of variation and their effect on the prevalence of hypercholesterolaemia.

    Science.gov (United States)

    Tolonen, Hanna; Ferrario, Marco; Kuulasmaa, Kari

    2005-06-01

    The estimation of population distribution of total cholesterol, as well as other blood lipids requires population surveys. Comparability of the estimates over time or between populations requires a predefined, standardized measurement protocol. This paper will assess the effect of variation in the pre-analytic procedures, on the estimation of population distribution of total cholesterol and the prevalence of hypercholesterolaemia. Implications of variation to real survey results are demonstrated on data collected during the WHO MONICA Project. The extent (%) of pre-analytic variations were determined by literature review. Simulations were then used to estimate the effect of these variations on the distribution of total cholesterol values. Three populations were selected as examples for different population distributions of total cholesterol levels and variations resulting from seasonal and postural changes, use of tourniquet, and serum versus plasma collection were simulated both individually and in combinations. Depending on the population distribution of total cholesterol, differences in pre-analytic procedures can explain a difference of up to 1.12 mmol/l in the mean total cholesterol between populations, and a difference up to 41% in the prevalence of hypercholesterolaemia (> or =6.5 mmol/l). Variation in results on measured total cholesterol levels due to differences in procedures during the pre-analytic stage can diminish substantially the reliability and comparability of measurements among surveys over time and between populations. The effect of pre-analytic variation in the population estimates of total cholesterol can be extensively reduced by standardization and training.

  19. Multiclass Total Variation Clustering

    Science.gov (United States)

    2014-12-01

    before thresholding) plotted over the fours and nines. Right: Solution f 4 from LSD [1] plotted over the fours and nines. 3.2 Transductive Framework From...of [11] and [3] with default parameters. We used the code available from [19] to test each NMF algorithm. All non-recursive algorithms ( LSD [1], NMFR...significantly improved upon previously reported results of LSD in particular. We allowed each non-recursive algorithm 10000 iterations using initial

  20. HIV Spending as a Share of Total Health Expenditure: An Analysis of Regional Variation in a Multi-Country Study

    Science.gov (United States)

    Amico, Peter; Aran, Christian; Avila, Carlos

    2010-01-01

    Background HIV has devastated numerous countries in sub-Saharan Africa and is a dominant health force in many other parts of the world. Its undeniable importance is reflected in the establishment of Millennium Development Goal No. 6. Unprecedented amounts of funding have been committed and disbursed over the past two decades. Many have argued that this enormous influx of funding has been detrimental to building stronger health systems in recipient countries. This paper examines the funding share for HIV measured against the total funding for health. Methodology/Principal Findings A descriptive analysis of HIV and health expenditures in 2007 from 65 countries was conducted. Comparable data from individual countries was used by applying a consistent definition for HIV expenditures and total health expenditures from NHAs to align them with National AIDS Assessment Reports. In 2007, the total public and international expenditure in LMICs for HIV was 1.6 percent of the total spending on health, while the share in SSA was 19.4 percent. HIV prevalence was six-fold higher in SSA than the next highest region and it is the only region whose share of HIV spending exceeded the burden of HIV DALYs. Conclusions/Significance The share of HIV spending across the 65 countries was quite moderate considering that the estimated share of deaths attributable to HIV stood at 3.8 percent and DALYs at 4.4 percent. Several high spending countries are using a large share of their total health spending for HIV health, but these countries are the exception rather than representative of the average SSA country. There is wide variation between regions, but the burden of disease also varies significantly. The percentage of HIV spending is a useful indicator for better understanding health care resources and their allocation patterns. PMID:20885986

  1. HIV spending as a share of total health expenditure: an analysis of regional variation in a multi-country study.

    Directory of Open Access Journals (Sweden)

    Peter Amico

    Full Text Available BACKGROUND: HIV has devastated numerous countries in sub-Saharan Africa and is a dominant health force in many other parts of the world. Its undeniable importance is reflected in the establishment of Millennium Development Goal No. 6. Unprecedented amounts of funding have been committed and disbursed over the past two decades. Many have argued that this enormous influx of funding has been detrimental to building stronger health systems in recipient countries. This paper examines the funding share for HIV measured against the total funding for health. METHODOLOGY/PRINCIPAL FINDINGS: A descriptive analysis of HIV and health expenditures in 2007 from 65 countries was conducted. Comparable data from individual countries was used by applying a consistent definition for HIV expenditures and total health expenditures from NHAs to align them with National AIDS Assessment Reports. In 2007, the total public and international expenditure in LMICs for HIV was 1.6 percent of the total spending on health, while the share in SSA was 19.4 percent. HIV prevalence was six-fold higher in SSA than the next highest region and it is the only region whose share of HIV spending exceeded the burden of HIV DALYs. CONCLUSIONS/SIGNIFICANCE: The share of HIV spending across the 65 countries was quite moderate considering that the estimated share of deaths attributable to HIV stood at 3.8 percent and DALYs at 4.4 percent. Several high spending countries are using a large share of their total health spending for HIV health, but these countries are the exception rather than representative of the average SSA country. There is wide variation between regions, but the burden of disease also varies significantly. The percentage of HIV spending is a useful indicator for better understanding health care resources and their allocation patterns.

  2. Variation.

    Science.gov (United States)

    Hamilton City Board of Education (Ontario).

    Suggestions for studying the topic of variation of individuals and objects (balls) to help develop elementary school students' measurement, comparison, classification, evaluation, and data collection and recording skills are made. General suggestions of variables that can be investigated are made for the study of human variation. Twelve specific…

  3. Short communication: bulk tank total bacterial count in dairy sheep: factors of variation and relationship with somatic cell count.

    Science.gov (United States)

    Gonzalo, C; Carriedo, J A; Beneitez, E; Juárez, M T; De La Fuente, L F; San Primitivo, F

    2006-02-01

    A total of 9,353 records for bulk tank total bacterial count (TBC) were obtained over 1 yr from 315 dairy ewe flocks belonging to the Sheep Improvement Consortium (CPO) in Castilla-León (Spain). Analysis of variance showed significant effects of flock, breed, month within flock, dry therapy, milking type and installation, and logSCC on logTBC. Flock and month within flock were important variation factors as they accounted for 22.0 and 22.1% of the variance, respectively. Considerable repeatability values were obtained for both random factors. Hand milking and bucket-milking machines elicited highest logTBC (5.31), whereas parlor systems with looped milkline (5.01) elicited the lowest logTBC. The implementation of dry therapy practice (5.12) showed significantly lower logTBC than when not used (5.25). Variability in logTBC among breeds ranged from 5.24 (Awassi) to 5.07 (Churra). However, clinical outbreaks of contagious agalactia did not increase TBC significantly. A statistically significant relationship was found between logTBC and logSCC, the correlation coefficient between the variables being r = 0.23. Programs for improving milk hygiene should be implemented for both total bacterial count and somatic cell count variables at the same time.

  4. Variation in major antioxidants and total antioxidant activity of Yuzu (Citrus junos Sieb ex Tanaka) during maturation and between cultivars.

    Science.gov (United States)

    Yoo, Kyung Mi; Lee, Ki Won; Park, Jae Bok; Lee, Hyong Joo; Hwang, In Kyeong

    2004-09-22

    Epidemiological studies suggest that a high consumption of fruits can reduce the risk of some cancers and cardiovascular disease, and this may be attributable to the antioxidant activity of vitamins and phenolic compounds. The present study investigated the variations in vitamin C, total phenolic, hesperidin, and naringin contents, and total antioxidant activity of yuzu (Citrus junos Sieb ex Tanaka)-which is a popular citrus fruit in Korea and Japan-between cultivars and during maturity. The amounts of phenolics and vitamin C and the antioxidant activity in all tested yuzu cultivars were higher in peel than in flesh. Ripening increased the total antioxidant activity and vitamin C content in both peel and flesh of yuzu. However, the amounts of all total phenolics, hesperidin, and naringin in peel increased with ripening, whereas they decreased slightly in flesh. There was a highly linear relationship between the vitamin C content and the total antioxidant activity in both peel (r(2) = 1.000) and flesh (r(2) =0.998), suggesting that vitamin C plays a key role in the antioxidant activity of yuzu. In addition, the contribution of each antioxidant to the total antioxidant activity of yuzu was determined using a 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging assay and is expressed here in terms of the vitamin C equivalent antioxidant capacity (VCEAC). The means of vitamin C, naringin, and hesperidin in yuzu were 90.4, 63.8, and 65.7 mg/100 g fresh yuzu, respectively. The relative VCEAC values of these compounds were in the following order: vitamin C (1.00) > naringin (0.195) > hesperidin (0.162). Therefore, the estimated contribution of each antioxidant to the total antioxidant capacity of 100 g of fresh yuzus is as follows (in mg of VCEAC): vitamin C (90.36 mg) > naringin (12.44 mg) > hesperidin (10.64 mg). Our results indicate that mature yuzu contains higher amounts of vitamin C and phenolics than other citrus fruits and could therefore be

  5. Spatial and Seasonal Variations of Total Petroleum Hydrocarbon in Surface Water and Sediment in Pearl River Delta.

    Science.gov (United States)

    Zhao, Jiandi; Yin, Pinghe; Zhao, Ling; Yu, Qiming; Lu, Gang

    2015-09-01

    A field study in the Pearl River Delta of China was conducted in order to describe to the spatial and seasonal variation of occurrence and concentrations of total petroleum hydrocarbon (TPH) in surface water and sediments. Petroleum hydrocarbons and isoprenoid alkanes were quantified by UV spectroscopy and gas chromatography with a mass selective detector. The concentrations of TPH ranged from 4.3 to 68.7 µg L(-1) in surface water, and from 66.6 to 1445 µg g(-1) in surface sediments. The ratios of pristine to phytane suggested that the main sources of TPH in the sediment were petroleum importation. The highest concentrations of TPH were present in the spring season. When compared with results from previous studies, it can be concluded that the Pearl River Delta was moderately polluted by TPH. No statistically significant correlations were observed between the concentrations of TPH in surface water and sediments.

  6. An Improved Total Variation Minimization Method Using Prior Images and Split-Bregman Method in CT Reconstruction

    Science.gov (United States)

    2016-01-01

    Compressive Sensing (CS) theory has great potential for reconstructing Computed Tomography (CT) images from sparse-views projection data and Total Variation- (TV-) based CT reconstruction method is very popular. However, it does not directly incorporate prior images into the reconstruction. To improve the quality of reconstructed images, this paper proposed an improved TV minimization method using prior images and Split-Bregman method in CT reconstruction, which uses prior images to obtain valuable previous information and promote the subsequent imaging process. The images obtained asynchronously were registered via Locally Linear Embedding (LLE). To validate the method, two studies were performed. Numerical simulation using an abdomen phantom has been used to demonstrate that the proposed method enables accurate reconstruction of image objects under sparse projection data. A real dataset was used to further validate the method. PMID:27689076

  7. Geographic and temporal patterns of variation in total mercury concentrations in blood of harlequin ducks and blue mussels from Alaska

    Science.gov (United States)

    Savoy, Lucas; Flint, Paul L.; Zwiefelhofer, Denny; Brant, Heather; Perkins, Christopher R.; Taylor, Robert J.; Lane, Oksana P.; Hall, Jefferson S.; Evers, David C.; Schamber, Jason

    2017-01-01

    We compared total mercury (Hg) concentrations in whole blood of harlequin ducks (Histrionicus histrionicus) sampled within and among two geographically distinct locations and across three years in southwest Alaska. Blue mussels were collected to assess correlation between Hg concentrations in locally available forage and birds. Mercury concentrations in harlequin duck blood were significantly higher at Unalaska Island (0.31 ± 0.19 mean ± SD, μg/g blood) than Kodiak Island (0.04 ± 0.02 mean ± SD, μg/g blood). We found no evidence for annual variation in blood Hg concentration between years at Unalaska Island. However, blood Hg concentration did vary among specific sampling locations (i.e., bays) at Unalaska Island. Findings from this study demonstrate harlequin ducks are exposed to environmental sources of Hg, and whole blood Hg concentrations are associated with their local food source.

  8. Ensuring convergence in total-variation-based reconstruction for accurate microcalcification imaging in breast X-ray CT

    CERN Document Server

    Jørgensen, Jakob H; Pan, Xiaochuan

    2011-01-01

    Breast X-ray CT imaging is being considered in screening as an extension to mammography. As a large fraction of the population will be exposed to radiation, low-dose imaging is essential. Iterative image reconstruction based on solving an optimization problem, such as Total-Variation minimization, shows potential for reconstruction from sparse-view data. For iterative methods it is important to ensure convergence to an accurate solution, since important image features, such as presence of microcalcifications indicating breast cancer, may not be visible in a non-converged reconstruction, and this can have clinical significance. To prevent excessively long computational times, which is a practical concern for the large image arrays in CT, it is desirable to keep the number of iterations low, while still ensuring a sufficiently accurate reconstruction for the specific imaging task. This motivates the study of accurate convergence criteria for iterative image reconstruction. In simulation studies with a realistic...

  9. Geographic and temporal patterns of variation in total mercury concentrations in blood of harlequin ducks and blue mussels from Alaska.

    Science.gov (United States)

    Savoy, Lucas; Flint, Paul; Zwiefelhofer, Denny; Brant, Heather; Perkins, Christopher; Taylor, Robert; Lane, Oksana; Hall, Jeff; Evers, David; Schamber, Jason

    2017-04-15

    We compared total mercury (Hg) concentrations in whole blood of harlequin ducks (Histrionicus histrionicus) sampled within and among two geographically distinct locations and across three years in southwest Alaska. Blue mussels were collected to assess correlation between Hg concentrations in locally available forage and birds. Mercury concentrations in harlequin duck blood were significantly higher at Unalaska Island (0.31±0.19 mean±SD, μg/g blood) than Kodiak Island (0.04±0.02 mean±SD, μg/g blood). We found no evidence for annual variation in blood Hg concentration between years at Unalaska Island. However, blood Hg concentration did vary among specific sampling locations (i.e., bays) at Unalaska Island. Findings from this study demonstrate harlequin ducks are exposed to environmental sources of Hg, and whole blood Hg concentrations are associated with their local food source. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Spherical deconvolution of multichannel diffusion MRI data with non-Gaussian noise models and total variation spatial regularization

    CERN Document Server

    Canales-Rodríguez, Erick J; Sotiropoulos, Stamatios N; Caruyer, Emmanuel; Aja-Fernández, Santiago; Radua, Joaquim; Mendizabal, Yosu Yurramendi; Iturria-Medina, Yasser; Melie-García, Lester; Alemán-Gómez, Yasser; Thiran, Jean-Philippe; Sarró, Salvador; Pomarol-Clotet, Edith; Salvador, Raymond

    2014-01-01

    Due to a higher capability in resolving white matter fiber crossings, Spherical Deconvolution (SD) methods have become very popular in brain fiber-tracking applications. However, while some of these estimation algorithms assume a central Gaussian distribution for the MRI noise, its real distribution is known to be non-Gaussian and to depend on many factors such as the number of coils and the methodology used to combine multichannel signals. Indeed, the two prevailing methods for multichannel signal combination lead to noise patterns better described by Rician and noncentral Chi distributions. Here we develop a Robust and Unbiased Model-BAsed Spherical Deconvolution (RUMBA-SD) technique intended to deal with realistic MRI noise. The algorithm relies on a maximum a posteriori formulation based on Rician and noncentral Chi likelihood models and includes a total variation (TV) spatial regularization term. By means of a synthetic phantom contaminated with noise mimicking patterns generated by data processing in mu...

  11. Non-local total-variation (NLTV) minimization combined with reweighted L1-norm for compressed sensing CT reconstruction

    Science.gov (United States)

    Kim, Hojin; Chen, Josephine; Wang, Adam; Chuang, Cynthia; Held, Mareike; Pouliot, Jean

    2016-09-01

    The compressed sensing (CS) technique has been employed to reconstruct CT/CBCT images from fewer projections as it is designed to recover a sparse signal from highly under-sampled measurements. Since the CT image itself cannot be sparse, a variety of transforms were developed to make the image sufficiently sparse. The total-variation (TV) transform with local image gradient in L1-norm was adopted in most cases. This approach, however, which utilizes very local information and penalizes the weight at a constant rate regardless of different degrees of spatial gradient, may not produce qualified reconstructed images from noise-contaminated CT projection data. This work presents a new non-local operator of total-variation (NLTV) to overcome the deficits stated above by utilizing a more global search and non-uniform weight penalization in reconstruction. To further improve the reconstructed results, a reweighted L1-norm that approximates the ideal sparse signal recovery of the L0-norm is incorporated into the NLTV reconstruction with additional iterates. This study tested the proposed reconstruction method (reweighted NLTV) from under-sampled projections of 4 objects and 5 experiments (1 digital phantom with low and high noise scenarios, 1 pelvic CT, and 2 CBCT images). We assessed its performance against the conventional TV, NLTV and reweighted TV transforms in the tissue contrast, reconstruction accuracy, and imaging resolution by comparing contrast-noise-ratio (CNR), normalized root-mean square error (nRMSE), and profiles of the reconstructed images. Relative to the conventional NLTV, combining the reweighted L1-norm with NLTV further enhanced the CNRs by 2-4 times and improved reconstruction accuracy. Overall, except for the digital phantom with low noise simulation, our proposed algorithm produced the reconstructed image with the lowest nRMSEs and the highest CNRs for each experiment.

  12. The role of midlatitude mixing barriers in creating the annual variation of total ozone in high northern latitudes

    Science.gov (United States)

    Gille, John; Karol, Svetlana; Kinnison, Douglas; Lamarque, Jean-Francois; Yudin, Valery

    2014-08-01

    Data from the HIgh Resolution Dynamics Limb Sounder (HIRDLS), the Microwave Limb Sounder (MLS), and the Whole Atmosphere Community Climate Model (WACCM) are used to investigate the annual variation of total column ozone in high northern latitudes. Downward transport of ozone-rich air by the residual mean circulation during autumn and winter bends ozone isopleths down and increases the high-latitude ozone amounts, leading to an ozone maximum at the end of the winter. During the summer months eddy mixing acts to restore pre-fall distributions of ozone. In this study the large-scale mixing in the lower stratosphere is analyzed using Nakamura's (1996) equivalent length formulation with observed and simulated ozone. The analysis of ozone mixing is performed in the tracer equivalent latitude-potential temperature coordinate system. Steep latitudinal gradients of ozone isopleths below about 500 K occur during the winter, where there are minima in the equivalent length, indicating barriers to mixing at 30°N-40°N. This transport barrier allows large ozone maxima to develop poleward of it. The barrier disappears over the summer, permitting latitudinal mixing of the high ozone air. Above 500 K mixing is more effective during the winter, so a large winter maximum does not occur. In both midlatitude and high latitude the lower stratospheric layer from 330 to 500 K doubles its ozone content from autumn to spring, compared with much smaller changes in the layer from 500 to 650 K. Our results confirm that the presence of the winter transport barrier in the lower stratosphere controls the seasonal variation of total ozone.

  13. Magnetic Field - Secular Variation of the Horizontal Component of the Total Field Intensity for the Epoch 2010.0 - Direct Download

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This map layer shows lines of equal annual change (secular variation) in the horizontal component of the total field intensity of the Earth's magnetic field, derived...

  14. Magnetic Field - Secular Variation of the Vertical Component of the Total Field Intensity for the Epoch 2010.0 - Direct Download

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This map layer shows lines of equal annual change (secular variation) in the vertical component of the total field intensity of the Earth's magnetic field, derived...

  15. PREDICTION OF THE ANTIDEPRESSANT RESPONSE TO TOTAL SLEEP-DEPRIVATION OF DEPRESSED-PATIENTS - LONGITUDINAL VERSUS SINGLE DAY ASSESSMENT OF DIURNAL MOOD VARIATION

    NARCIS (Netherlands)

    REININK, E; BOUHUYS, AL; GORDIJN, MCM; VANDENHOOFDAKKER, RH

    1993-01-01

    The relationship between diurnal variation of mood and the clinical response to total sleep deprivation (TSD) was investigated in 43 depressed patients. The question asked was whether the propensity to produce diurnal variations of mood or the actual mood course on the day before TSD determines the

  16. A clinical evaluation of total variation-Stokes image reconstruction strategy for low-dose CT imaging of the chest

    Science.gov (United States)

    Liu, Yan; Zhang, Hao; Moore, William; Bhattacharji, Priya; Liang, Zhengrong

    2015-03-01

    One hundred "normal-dose" computed tomography (CT) studies of the chest (i.e., 1,160 projection views, 120kVp, 100mAs) data sets were acquired from the patients who were scheduled for lung biopsy at Stony Brook University Hospital under informed consent approved by our Institutional Review Board. To mimic low-dose CT imaging scenario (i.e., sparse-view scan), sparse projection views were evenly extracted from the total 1,160 projections of each patient and the total radiation dose was reduced according to how many sparse views were selected. A standard filtered backprojection (FBP) algorithm was applied to the 1160 projections to produce reference images for comparison purpose. In the low-dose scenario, both the FBP and total variation-stokes (TVS) algorithms were applied to reconstruct the corresponding low-dose images. The reconstructed images were evaluated by an experienced thoracic radiologist against the reference images. Both the low-dose reconstructions and the reference images were displayed on a 4- megapixel monitor in soft tissue and lung windows. The images were graded by a five-point scale from 0 to 4 (0, nondiagnostic; 1, severe artifact with low confidence; 2, moderate artifact or moderate diagnostic confidences; 3, mild artifact or high confidence; 4, well depicted without artifacts). Quantitative evaluation measurements such as standard deviations for different tissue types and universal quality index were also studied and reported for the results. The evaluation concluded that the TVS can reduce the view number from 1,160 to 580 with slightly lower scores as the reference, resulting in a dose reduction to close 50%.

  17. Spatial and temporal variations of loads and sources of total and dissolved Phosphorus in a set of rivers (Western France).

    Science.gov (United States)

    Legeay, Pierre-Louis; Moatar, Florentina; Gascuel-Odoux, Chantal; Gruau, Gérard

    2015-04-01

    In intensive agricultural regions with important livestock farming, long-term land application of Phosphorus (P) both as chemical fertilizer and animal wastes, have resulted in elevated P contents in soils. Since we know that high P concentrations in rivers is of major concern, few studies have been done at to assess the spatiotemporal variability of P loads in rivers and apportionment of point and nonpoint source in total loads. Here we focus on Brittany (Western France) where even though P is a great issue in terms of human and drinking water safety (cyano-toxins), environmental protection and economic costs for Brittany with regards to the periodic proliferations of cyanobacteria that occur every year in this region, no regional-scale systematic study has been carried out so far. We selected a set of small rivers (stream order 3-5) with homogeneous agriculture and granitic catchment. By gathering data from three water quality monitoring networks, covering more than 100 measurements stations, we provide a regional-scale quantification of the spatiotemporal variability of dissolved P (DP) and total P (TP) interannual loads from 1992 to 2012. Build on mean P load in low flows and statistical significance tests, we developed a new indicator, called 'low flow P load' (LFP-load), which allows us to determine the importance of domestic and industrial P sources in total P load and to assess their spatiotemporal variability compared to agricultural sources. The calculation and the map representation of DP and TP interannual load variations allow identification of the greatest and lowest P contributory catchments over the study period and the way P loads of Brittany rivers have evolved through time. Both mean DP and TP loads have been divided by more than two over the last 20 years. Mean LFDP-load decreased by more than 60% and mean LFTP-load by more than 45% on average over the same period showing that this marked temporal decrease in total load is largely due to the

  18. Anatomically weighted second-order total variation reconstruction of 23Na MRI using prior information from 1H MRI.

    Science.gov (United States)

    Gnahm, Christine; Nagel, Armin M

    2015-01-15

    Sodium ((23)Na) MRI is a noninvasive tool to assess cell viability, which is linked to the total tissue sodium concentration (TSC). However, due to low in vivo concentrations, (23)Na MRI suffers from low signal-to-noise ratio (SNR) and limited spatial resolution. As a result, image quality is compromised by Gibbs ringing artifacts and partial volume effects. An iterative reconstruction algorithm that incorporates prior information from (1)H MRI is developed to reduce partial volume effects and to increase the SNR in non-proton MRI. Anatomically weighted second-order total variation (AnaWeTV) is proposed as a constraint for compressed sensing reconstruction of 3D projection reconstruction (3DPR) data. The method is evaluated in simulations and a MR measurement of a multiple sclerosis (MS) patient by comparing it to gridding and other reconstruction techniques. AnaWeTV increases resolution of known structures and reduces partial volume effects. In simulated MR brain data (nominal resolution Δx(3) = 3 × 3 × 3 mm(3)), the intensity error of four small MS lesions was reduced from (6.9 ± 3.8)% (gridding) to (2.8 ± 1.4)% (AnaWeTV with T2-weighted reference images). Compared to gridding, a substantial SNR increase of 130% was found in the white matter of the MS patient. The algorithm is robust against misalignment of the prior information on the order of the (23)Na image resolution. Features without prior information are still reconstructed with high contrast. AnaWeTV allows a more precise quantification of TSC in structures with prior knowledge. Thus, the AnaWeTV algorithm is in particular beneficial for the assessment of tissue structures that are visible in both (23)Na and (1)H MRI.

  19. MR image segmentation and bias field estimation based on coherent local intensity clustering with total variation regularization.

    Science.gov (United States)

    Tu, Xiaoguang; Gao, Jingjing; Zhu, Chongjing; Cheng, Jie-Zhi; Ma, Zheng; Dai, Xin; Xie, Mei

    2016-12-01

    Though numerous segmentation algorithms have been proposed to segment brain tissue from magnetic resonance (MR) images, few of them consider combining the tissue segmentation and bias field correction into a unified framework while simultaneously removing the noise. In this paper, we present a new unified MR image segmentation algorithm whereby tissue segmentation, bias correction and noise reduction are integrated within the same energy model. Our method is presented by a total variation term introduced to the coherent local intensity clustering criterion function. To solve the nonconvex problem with respect to membership functions, we add auxiliary variables in the energy function such as Chambolle's fast dual projection method can be used and the optimal segmentation and bias field estimation can be achieved simultaneously throughout the reciprocal iteration. Experimental results show that the proposed method has a salient advantage over the other three baseline methods on either tissue segmentation or bias correction, and the noise is significantly reduced via its applications on highly noise-corrupted images. Moreover, benefiting from the fast convergence of the proposed solution, our method is less time-consuming and robust to parameter setting.

  20. Linearized primal-dual methods for linear inverse problems with total variation regularization and finite element discretization

    Science.gov (United States)

    Tian, Wenyi; Yuan, Xiaoming

    2016-11-01

    Linear inverse problems with total variation regularization can be reformulated as saddle-point problems; the primal and dual variables of such a saddle-point reformulation can be discretized in piecewise affine and constant finite element spaces, respectively. Thus, the well-developed primal-dual approach (a.k.a. the inexact Uzawa method) is conceptually applicable to such a regularized and discretized model. When the primal-dual approach is applied, the resulting subproblems may be highly nontrivial and it is necessary to discuss how to tackle them and thus make the primal-dual approach implementable. In this paper, we suggest linearizing the data-fidelity quadratic term of the hard subproblems so as to obtain easier ones. A linearized primal-dual method is thus proposed. Inspired by the fact that the linearized primal-dual method can be explained as an application of the proximal point algorithm, a relaxed version of the linearized primal-dual method, which can often accelerate the convergence numerically with the same order of computation, is also proposed. The global convergence and worst-case convergence rate measured by the iteration complexity are established for the new algorithms. Their efficiency is verified by some numerical results.

  1. GPU-based Fast Cone Beam CT Reconstruction from Undersampled and Noisy Projection Data via Total Variation

    CERN Document Server

    Jia, Xun; Li, Ruijiang; Song, William Y; Jiang, Steve B

    2010-01-01

    Cone-beam CT (CBCT) plays an important role in image guided radiation therapy (IGRT). However, the large radiation dose from serial CBCT scans in most IGRT procedures raises a clinical concern, especially for pediatric patients who are essentially excluded from receiving IGRT for this reason. To lower the imaging dose, we have developed a fast GPU-based CBCT reconstruction algorithm. The CBCT is reconstructed by minimizing an energy functional consisting of a data fidelity term and a total variation regularization term. We developed a GPU-friendly version of the forward-backward splitting algorithm to solve this model. Multi-grid technique is also employed. It is found that 20~40 x-ray projections are sufficient to reconstruct images with satisfactory quality for IGRT. The reconstruction time ranges from 77 to 130 sec on a NVIDIA Tesla C1060 GPU card, depending on the number of projections used, which is estimated about 100 times faster than similar iterative reconstruction approaches. Moreover, phantom studi...

  2. Image reconstruction based on total-variation minimization and alternating direction method in linear scan computed tomography

    Institute of Scientific and Technical Information of China (English)

    Zhang Han-Ming; Wang Lin-Yuan; Yah Bin; Li Lei; Xi Xiao-Qi; Lu Li-Zhong

    2013-01-01

    Linear scan computed tomography (LCT) is of great benefit to online industrial scanning and security inspection due to its characteristics of straight-line source trajectory and high scanning speed.However,in practical applications of LCT,there are challenges to image reconstruction due to limited-angle and insufficient data.In this paper,a new reconstruction algorithm based on total-variation (TV) minimization is developed to reconstruct images from limited-angle and insufficient data in LCT.The main idea of our approach is to reformulate a TV problem as a linear equality constrained problem where the objective function is separable,and then minimize its augmented Lagrangian function by using alternating direction method (ADM) to solve subproblems.The proposed method is robust and efficient in the task of reconstruction by showing the convergence of ADM.The numerical simulations and real data reconstructions show that the proposed reconstruction method brings reasonable performance and outperforms some previous ones when applied to an LCT imaging problem.

  3. Morphological Characterization and Variation in the Total Content of Reducing Sugars in Wild Populations of Agave angustifolia Haw

    Directory of Open Access Journals (Sweden)

    Martin Esqueda

    2011-01-01

    Full Text Available Problem statement: Bacanora, a spirit, is distilled from wild populations of Agave angustifolia Haw. Loss of biodiversity must be taken into account when proposing sustainable management actions for this resource. In this study we identified the morphological variants of this species, as well as the weight and Total Content of Reducing Sugars (TRS in the stem of the agave. Approach: Twenty-three morphometric variables were measured in three wild populations of A. angustifolia distributed along the western slopes of the Sierra Madre Mountain Range in Sonora, Mexico. The relationship of plant weight to stem TRS was evaluated using multivariate analyses. Results: Canonical discriminate analysis explained 100% of the morphological variation with just two canonical variables (pConclusion: Based on this analysis and previous studies of genetic variability and cytogenetic on the same individuals, morphologically and genetically related groups of agave were detected and also had heavier stems and a higher TRS content. These plants can be considered the basis for the selection of germplasm.

  4. Uncertainty analysis of total phosphorus spatial-temporal variations in the Yangtze River Estuary using different interpolation methods.

    Science.gov (United States)

    Liu, Ruimin; Chen, Yaxin; Sun, Chengchun; Zhang, Peipei; Wang, Jiawei; Yu, Wenwen; Shen, Zhenyao

    2014-09-15

    Interpolation processes and results are generally accompanied by uncertainty which affects the spatial and temporal properties of pollutants. Based on the 4 period sample data of total phosphorus (TP) collected from the Yangtze River Estuary (YRE) in 2010 and 2011, the uncertainty of spatial-temporal variation was analyzed with interpolation methods of inverse distance weighted (IDW), local polynomial interpolation (LPI), ordinary kriging (OK) and disjunctive kriging (DK). The root mean square errors (RMSE) and the mean relative errors (MRE) were used to analyze the accuracy of different interpolation methods. The results showed that the uncertainty of DK was the lowest and the uncertainty of LPI was the highest among the 4 methods. The subtraction results between different interpolation methods showed that there was some distinct area of value in the disparate interval (not in [-0.05, 0.05] (mg/L)) in the 4 seasonal results, which was mainly distributed in the boundary region and around some sample sites. Both standard deviation (SD) and coefficient of variance (CV) in August 2010 were the highest in the 4 seasons and annual mean. The uncertainty may be caused by choice of interpolation methods, spatial data discrepancy and the lack of sample data.

  5. Low-dose 4D cone-beam CT via joint spatiotemporal regularization of tensor framelet and nonlocal total variation

    Science.gov (United States)

    Han, Hao; Gao, Hao; Xing, Lei

    2017-08-01

    Excessive radiation exposure is still a major concern in 4D cone-beam computed tomography (4D-CBCT) due to its prolonged scanning duration. Radiation dose can be effectively reduced by either under-sampling the x-ray projections or reducing the x-ray flux. However, 4D-CBCT reconstruction under such low-dose protocols is prone to image artifacts and noise. In this work, we propose a novel joint regularization-based iterative reconstruction method for low-dose 4D-CBCT. To tackle the under-sampling problem, we employ spatiotemporal tensor framelet (STF) regularization to take advantage of the spatiotemporal coherence of the patient anatomy in 4D images. To simultaneously suppress the image noise caused by photon starvation, we also incorporate spatiotemporal nonlocal total variation (SNTV) regularization to make use of the nonlocal self-recursiveness of anatomical structures in the spatial and temporal domains. Under the joint STF-SNTV regularization, the proposed iterative reconstruction approach is evaluated first using two digital phantoms and then using physical experiment data in the low-dose context of both under-sampled and noisy projections. Compared with existing approaches via either STF or SNTV regularization alone, the presented hybrid approach achieves improved image quality, and is particularly effective for the reconstruction of low-dose 4D-CBCT data that are not only sparse but noisy.

  6. Development of NIR calibration models to assess year-to-year variation in total non-structural carbohydrates in grasses using PLSR

    DEFF Research Database (Denmark)

    Shetty, Nisha; Gislum, René; Jensen, Anne Mette Dahl

    2012-01-01

    Near-infrared (NIR) spectroscopy was used in combination with chemometrics to quantify total nonstructural carbohydrates (TNC) in grass samples in order to overcome year-to-year variation. A total of 1103 above-ground plant and root samples were collected from different field and pot experiments ...

  7. Variation of Total Lipid and Fatty Acid Amount and Compositions in Muscles of Capoeta trutta and Barbus rajanorum mystaceus During Reproduction Period

    OpenAIRE

    KONAR, Vahit; CANPOLAT, Ayhan; YILMAZ, Ökkeş

    2014-01-01

    In this study, the variation of total lipid and fatty acid composition in muscle tissues of females and males of Copoeta trutta and Barbus rajanorum mystaceus living in Keban Dam Lake (Elazig) were examined. It was observed that the amount of total lipid in muscle tissues of C. trutta (p

  8. Annual and seasonal variation of turbidity, total dissolved solids, nitrate and nitrite in the Parsabad water treatment plant, Iran

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Zare

    2013-01-01

    Full Text Available Aims: This study investigated the annual and seasonal variation of turbidity; total dissolved solid (TDS, nitrate and nitrite in Parsabad water treatment plant (WTP, Iran. Materials and Methods: The water samples were obtained from the inlet and outlet of Parsabad WTP from February 2002 to June 2009. The samples′ turbidity, TDS, nitrate, nitrite, pH, and temperature were measured according to standard methods once a month and the average of these parameters were calculated for each season of year. Results: The maximum concentration of inlet turbidity, TDS, nitrate and nitrite were 691, 700.5, 25, and 0.17 mg/l, respectively. These parameters for outlet samples in the study period were 3.0, 696.7, 18, and 0.06 mg/l, respectively. While these concentrations in outlet zone were lower than World Health Organization (WHO or United States Environmental Protection Agency (US-EPA water quality guidelines, WTP could not reduce the TDS, nitrate, nitrite and pH value and these parameters were not different in the inlet and outlet samples. However, the WTP reduced the turbidity significantly with an efficiency of up to 85%. Conclusion: This study showed that a common WTP with rapid sand filtration can treat a maximum river turbidity of 700 NTU in several years. As no differences were observed between inlet and outlet TDS, nitrate, nitrite and pH in the studied WTP. It can be concluded that compensatory schemes should be predicted for modification of these parameters when they exceed the standards in the emergency situations.

  9. Iterative image reconstruction for sparse-view CT using normal-dose image induced total variation prior.

    Directory of Open Access Journals (Sweden)

    Jing Huang

    Full Text Available X-ray computed tomography (CT iterative image reconstruction from sparse-view projection data has been an important research topic for radiation reduction in clinic. In this paper, to relieve the requirement of misalignment reduction operation of the prior image constrained compressed sensing (PICCS approach introduced by Chen et al, we present an iterative image reconstruction approach for sparse-view CT using a normal-dose image induced total variation (ndiTV prior. The associative objective function of the present approach is constructed under the penalized weighed least-square (PWLS criteria, which contains two terms, i.e., the weighted least-square (WLS fidelity and the ndiTV prior, and is referred to as "PWLS-ndiTV". Specifically, the WLS fidelity term is built based on an accurate relationship between the variance and mean of projection data in the presence of electronic background noise. The ndiTV prior term is designed to reduce the influence of the misalignment between the desired- and prior- image by using a normal-dose image induced non-local means (ndiNLM filter. Subsequently, a modified steepest descent algorithm is adopted to minimize the associative objective function. Experimental results on two different digital phantoms and an anthropomorphic torso phantom show that the present PWLS-ndiTV approach for sparse-view CT image reconstruction can achieve noticeable gains over the existing similar approaches in terms of noise reduction, resolution-noise tradeoff, and low-contrast object detection.

  10. Segmentation and Analysis of Corpus Callosum in Alzheimer MR Images using Total Variation Based Diffusion Filter and Level Set Method.

    Science.gov (United States)

    Anandh, K R; Sujatha, C M; Ramakrishnan, S

    2015-01-01

    Alzheimer’s Disease (AD) is a common form of dementia that affects gray and white matter structures of brain. Manifestation of AD leads to cognitive deficits such as memory impairment problems, ability to think and difficulties in performing day to day activities. Although the etiology of this disease is unclear, imaging biomarkers are highly useful in the early diagnosis of AD. Magnetic resonance imaging is an indispensible non-invasive imaging modality that reflects both the geometry and pathology of the brain. Corpus Callosum (CC) is the largest white matter structure as well as the main inter-hemispheric fiber connection that undergoes regional alterations due to AD. Therefore, segmentation and feature extraction are predominantly essential to characterize the CC atrophy. In this work, an attempt has been made to segment CC using edge based level set method. Prior to segmentation, the images are pre-processed using Total Variation (TV) based diffusion filtering to enhance the edge information. Shape based geometric features are extracted from the segmented CC images to analyze the CC atrophy. Results show that the edge based level set method is able to segment CC in both the normal and AD images. TV based diffusion filtering has performed uniform region specific smoothing thereby preserving the texture and small scale details of the image. Consequently, the edge map of CC in both the normal and AD are apparently sharp and distinct with continuous boundaries. This facilitates the final contour to correctly segment CC from the nearby structures. The extracted geometric features such as area, perimeter and minor axis are found to have the percentage difference of 5.97%, 22.22% and 9.52% respectively in the demarcation of AD subjects. As callosal atrophy is significant in the diagnosis of AD, this study seems to be clinically useful.

  11. Evaluation of the Applicability of the Chapman-Miller Method on Variation of the Geomagnetic Total Intensity Field in Taiwan from 1988 to 2007

    Directory of Open Access Journals (Sweden)

    Chieh-Hung Chen

    2009-01-01

    Full Text Available The solar (S and lunar (L variations of geomagnetic fields at the horizontal (H, declination (D, and the downward vertical component data (Z are modeled by the Chap man-Miller method with four order harmonics. In this paper, we compare S and L variations of the geomagnetic total intensity field using a consistent method with 3-component data for seasonal variations (summer, winter, and equinox for three distinct phases during the years 1988 - 2007. The results show that consistency in the S and L variations for geomagnetic total intensity indicates normal stations and discrepancies are occurred due to data quality. In application, consistent results also prove that the function of the magnetometers at TW was normal and that large anomalies were certainly in existence during the Chia-Yi earthquake.

  12. Circadian variation in serum free and total insulin-like growth factor (IGF)-I and IGF-II in untreated and treated acromegaly and growth hormone deficiency

    DEFF Research Database (Denmark)

    Skjaerbaek, Christian; Frystyk, Jan; Kaal, Andreas

    2000-01-01

    to the nocturnal increase in IGF binding protein-1. In this study we have investigated the circadian variation in circulating free IGF-I and IGF-II in patients with acromegaly and patients with adult onset growth hormone deficiency. PATIENTS: Seven acromegalic patients were studied with and without treatment...... no significant circadian variations in free IGF-I or free IGF-II in either of the two occasions. In contrast, there was a significant circadian variation of total IGF-I after adjustment for changes in plasma volume in both treated and untreated acromegaly and GH deficiency in all cases with a peak between 0300 h...

  13. Circadian variation in serum free and total insulin-like growth factor (IGF)-I and IGF-II in untreated and treated acromegaly and growth hormone deficiency

    DEFF Research Database (Denmark)

    Skjaerbaek, Christian; Frystyk, Jan; Kaal, Andreas;

    2000-01-01

    to the nocturnal increase in IGF binding protein-1. In this study we have investigated the circadian variation in circulating free IGF-I and IGF-II in patients with acromegaly and patients with adult onset growth hormone deficiency. PATIENTS: Seven acromegalic patients were studied with and without treatment...... no significant circadian variations in free IGF-I or free IGF-II in either of the two occasions. In contrast, there was a significant circadian variation of total IGF-I after adjustment for changes in plasma volume in both treated and untreated acromegaly and GH deficiency in all cases with a peak between 0300 h...

  14. Interannual variations in the zonal asymmetry of the subpolar latitudes total ozone column during the austral spring

    Directory of Open Access Journals (Sweden)

    Eduardo A. Agosta

    2010-06-01

    Full Text Available The Southern Hemisphere midlatitude Total Ozone Column (TOC shows a horseshoe like structure with a minimum which appears to have two preferential extreme positions during October: one, near southern South America, the other, near the Greenwich Meridian approximately. The interannual zonal ozone asymmetry exists independently of the variations induced by the 11-year solar cycle, the Quasi-Biennial Oscillation (QBO and planetary wave activity inducing the Brewer-Dobson circulation. The classification and climatological composition of these two extreme ozone-minimum positions allows for the observations of statistically significant patterns in geopotential height and zonal winds associated with the quasi-stationary wave 1, extending throughout lower stratosphere. The changes in the quasi-stationary wave 1 associated with the extreme TOC positions appear to have sinks and sources determining transient interactions between troposphere and the stratosphere. Thus, distinct climate states in the troposphere seem to be dynamically linked with the state of the stratosphere and ozone layer. The migration of the TOC trough from southern South America to the east during the 1990s can be related to changes in the troposphere/stratosphere coupling through changes in the Southern Annular Mode variability in spring.La Columna Total de Ozono (CTO de las latitudes medias del Hemisferio Sur muestra una estructura de herradura con un mínimo que muestra tener dos posiciones preferenciales extremas durante octubre: uno, en las cercanías del sur de Sudamérica, y el otro, cerca del meridiano de Greenwich. La asimetría zonal de ozono existe independientemente de las variaciones inducidas por el ciclo solar de 11 años, la Oscilación Cuasi-Bianual (QBO y la actividad de onda planetaria asociada a la circulación de Brewer-Dobson. La clasificación y composición climatológica de estas dos situaciones longitudinalmente extremas de mínimo de ozono permite observar

  15. Biological variation and reference intervals for circulating osteopontin, osteoprotegerin, total soluble receptor activator of nuclear factor kappa B ligand and high-sensitivity C-reactive protein

    DEFF Research Database (Denmark)

    Sennels, Henriette Pia; Jacobsen, S; Jensen, T;

    2007-01-01

    with sandwich ELISA; serum total sRANKL concentration was determined using a two-site sandwich ELISA; and hsCRP was analysed by turbidimetry in 300 Danish blood donors (183 M and 117 F) with a median age of 43 years (range 18-64 years). Variability due to biological variation and sampling time was studied...

  16. The Representation of the Total Variation and the Metric Derivative for Fuzzy Bounded Variation Functions%模糊有界变差函数全变差的积分表示与距离导数

    Institute of Scientific and Technical Information of China (English)

    巩增泰; 白玉娟

    2011-01-01

    The metric derivative of the fuzzy-number-valued functions and the representation of the total variation for the fuzzy-number-valued function which is of bounded variation are defined and discussed. It is proved that the fuzzy absolutely continuous functions are metrically differentiable almost everywhere, and the integration of its metric derivative equals to the total variation of the primitive. Finally, the representation of the total variation for the fuzzy-number-valued functions which is of bounded variation is given.%定义和讨论了模糊数值函数的距离导数,给出了模糊有界变差函数全变差的积分表示.发现模糊绝对连续函数是几乎处处距离可导的,距离导数的积分等于其原函数的总变差,从而给出了模糊有界变差函数全变差的积分表示.

  17. Temporal and spatial variations in total suspended and dissolved solids in the upper part of Manoa stream, Hawaii

    NARCIS (Netherlands)

    Augustijn, Dionysius C.M.; Fares, Ali; Tran, Dai Ngia

    2011-01-01

    Hawaiian watersheds are small, steep, and receive high intensity rainfall events of non-uniform distribution. These geographic and weather patterns result in flashy streams of strongly variable water quality even within various stream segments. Total suspended solids (TSS) and total dissolved solids

  18. Temporal and Spatial Variation in the Abundance of Total and Pathogenic Vibrio parahaemolyticus in Shellfish in China.

    Directory of Open Access Journals (Sweden)

    Haihong Han

    Full Text Available We investigated the abundance of total and pathogenic Vibrio parahaemolyticus in shellfish sampled from four provinces in China during May 2013 and March 2014 using the most probable number-polymerase chain reaction (MPN-PCR method. Total V. parahaemolyticus was detected in 67.7% of 496 samples. A total of 38.1% and 10.1% of samples exceeded 1,000 MPN g(-1 and 10,000 MPN g(-1, respectively. V. parahaemolyticus densities followed a seasonal and geographical trend, with Guangxi and Sichuan shellfish possessing total V. parahaemolyticus levels that were 100-fold higher than those of the Liaoning and Shandong regions. Moreover, the levels of V. parahaemolyticus were at least 10-fold higher in the summer and autumn than in the cooler seasons. Pathogenic V. parahaemolyticus levels were generally lower than total V. parahaemolyticus levels by several log units and tended to be high in samples contaminated with high total V. parahaemolyticus levels. The aqua farms had a lower prevalence but higher abundance of total V. parahaemolyticus compared to retail markets. The catering markets showed the lowest levels of total V. parahaemolyticus, but 20.0% of samples exceeded 1,000 MPN g(-1. The levels of both total and pathogenic V. parahaemolyticus in oysters were higher than in clams. The log-transformed abundance of V. parahaemolyticus was significantly correlated with both water temperature and air temperature but not water salinity. These results provide baseline contamination data of V. parahaemolyticus in shellfish in China, which can be applied to local risk assessments to prioritize risk control to key sectors and evaluate the effectiveness of future control measures.

  19. Solar activity indices as a proxy for the variation of ionospheric Total Electron Content (TEC) over Bahir Dar, Ethiopia during the year 2010-2014

    Science.gov (United States)

    Kassa, Tsegaye; Tilahun, Samson; Damtie, Baylie

    2017-09-01

    This paper was aimed at investigating the solar variations of vTEC as a function of solar activity parameters, EUV and F10.7 radio flux. The daily values of ionospheric vertical Total Electron Content (vTEC) were observed using a dual frequency GPS receiver deployed at Bahir Dar (11.6°N and 37.36°E), Ethiopia. Measurements were taken during the period of 2010-2014 for successive five years and analysis was done on only quiet day observations. A quadratic fit was used as a model to describe the daily variation of vTEC in relation to solar parameters. Linear and non-linear coefficients of the vTEC variations were calculated in order to capture the trend of the variation. The variation of vTEC have showed good agreement with the trend of solar parameters in almost all of the days we consider during the period of our observations. We have explicitly observed days with insignificant TECU deviation (eg. modeling with respect to EUV, DOY = 49 in 2010 and modeling with respect to F10.7, DOY = 125 in 2012 and the like) and days with maximum deviation (about 50 TECU). A maximum deviation were observed, on average, during months of equinox whereas minimum during solstice months. This implies that there is a need to consider more parameters, including EUV and F10.7, that can affect the variation of vTEC during equinox seasons. Relatively, small deviations was observed in modeling vTEC as a function of EUV compared to that of the variation due to F10.7 cm flux. This may also tell us that EUV can be more suitable in modeling the solar variation of vTEC especially for longterm trends. Even though, the linear trend of solar variations of vTEC was frequently observed, significant saturation and amplification trends of the solar variations of vTEC were also observed to some extent across the months of the years we have analyzed. This mixed trend of the solar variation of vTEC implies the need for thorough investigation on the effect of solar parameters on TEC. However, based on

  20. Spatial and temporal variations in pH and total alkalinity at the beginning of the rainy season in the Changjiang Estuary, China

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The results of field observation carried out in May 2003 were used to examine pH and total alkalinity behaviors in the Changjiang Estuary. It was showed that pH and total alkalinity took on clear spatial variations in values with the minima in the low salinity region.Like salinity, transect distributions of pH and total alkalinity (TA) in a downriver direction had a sharp gradient each. These gradients appeared in such a sequence that the TA gradient was earlier than salinity and pH gradients, and the salinity gradient was earlier than the pH gradient. These distribution characteristics seemed to be strongly influenced by the mixing process of freshwater and seawater,for both pH and total alkalinity had significant linear relationships with salinity and temperature. For pH, phytoplankton activities also had a significant impact upon its spatial distribution. During a period of 48 h, pH and total alkalinity changed within wide ranges for every layer of the two anchor stations, namely, Stas 13 and 20, which were located at the mixed water mass and seawater mass, respectively. For both Stas 13 and 20, pH and TA fluctuation of every layer could be very wide during a 4 h period. As a whole, the data of the two anchor stations showed that neither variations in salinity and temperature nor phytoplankton activities were the main factors strongly influencing the total alkalinity temporal variability on a small time scale. The data of Sta. 20 implied that both salinity variation and phytoplankton activities had a significant influence on pH temporal variability, but the same conclusion could not be drawn from the data of Sta. 13.

  1. Numerical analysis of variations in posterior cruciate ligament properties and balancing techniques on total knee arthroplasty loading.

    NARCIS (Netherlands)

    Zelle, J.; Heesterbeek, P.J.; De Waal Malefijt, M.; Verdonschot, Nicolaas Jacobus Joseph

    2010-01-01

    Total knee arthroplasty (TKA) is a widely used and successful orthopaedic procedure. During TKA, the posterior cruciate ligament (PCL) can either be retained or substituted by a post-cam mechanism. One of the main functions of the PCL is to facilitate femoral rollback during knee flexion. For adequa

  2. [Total proteins of the cerebrospinal fluid obtained by punction of the cisterna magna: normal values. Variations related to sex].

    Science.gov (United States)

    Vermes, L M; Ferri, R G; Aisen, J; Marlet, J M

    1976-12-01

    The total protein content of CSF collected from the cisterna magna (cisternal fluid) of 98 patients (58 males and 40 females) with no neurological diseases was determined by the colorimetric method devised by Lowry and co-workers. This method has been previously chosen based mainly on it's sensitivity, accuracy and low fluid consumption. The CSF samples were normal with regard to pressure, color, citology and it's content in glucose, chloride and urea. Complement fixation tests for syphilis and cisticercosis, as well as the globulin tests (Pandy, Nonne--Appelt and Takata-Ara) were negative. The average value and the normal range of cisternal fluid total protein was calculated for the mixed population (males and females). The mean protein value was 26.78 mg/100 ml, the lower and upper limits were respectively 13.20 and 40.36 mg/100 ml. These data are higher than those stated in some publications, and factors that could interfere in the different results mentioned in the literature are briefly discussed. Since the statistical analysis of the results showed that the mean total protein concentration in males (28.76 mg/100 ml) was higher than in females (23.91 mg/100 ml), normal limits for each sex were established: 16.96 to 47.13 mg/100 ml for males and 14.76 to 42.76 mg/100 ml for females.

  3. Ontogenetic Variation of Total Phenolics and Antioxidant Activity in Roots, Leaves and Flowers of Astragalus compactus Lam. (Fabaceae

    Directory of Open Access Journals (Sweden)

    Somayeh Naghiloo

    2012-05-01

    Full Text Available Introduction: The potential health risks and toxicity of synthetic antioxidants resulted in an upsurge of interest in phytochemicals as new sources of natural antioxidants. Phenolics of Astragalus L. (Fabaceae possess antioxidant properties and have been shown to have a protective effect against several degenerative diseases. The objective of this study was to determine total phenolics and antioxidant activity of methanolic extracts from different parts of A. compactus Lam. at different phenological phases and to investigate the correlations between antioxidation and the contents of the total phenolics. Methods: Total phenolic content (TPC was determined using the Folin-Ciocalteau reagent and the antioxidant capacity was evaluated with the 1,1-diphenyl-2-picrylhydrazyl (DPPH test. Results: Generally, the TPC in leaves was higher than that of the roots and flowers. TPC in leaves, roots and flowers of the species varied from 5.01-8.25, 4.29-7.89 and 4.19 μg GAE/mg DW, respectively. In addition, roots and leaves at fructification stage possessed higher TPC than vegetative and flowering stages. Therefore, the leaf extracts at fructification phase showed the highest TPC that accompanied with best antioxidant activity. In the root extracts, fructification stage was also characterized by the highest antioxidant activity. Conclusion: A positive relationship between antioxidant activity and TPC showed that phenolics were the dominant antioxidant components in the species. Results obtained suggest that A. compactus methanolic extracts may serve as potential sources of natural phenolic antioxidants and that the fructification phase could be considered as the best stage for the harvesting of this plant.

  4. Variation in antioxidant, and antibacterial activities and total phenolic content of the bulbs of mooseer (Allium hirtifolium Boiss.

    Directory of Open Access Journals (Sweden)

    Abdollah GHASEMI PIRBALOUTI

    2015-11-01

    Full Text Available Allium hirtifolium Boiss. (mooseer belonging to the family Alliaceae, is an endemic species of Iran which grows wild in the Zagros Mountains range, western and southwestern Iran. The bulb of A. hirtifolium has been used as a flavouring agent, especially dairy foods and pickles by the indigenous people, southwestern Iran. In this study, the bulbs of various populations of the plant were collected from the alpine regions in Chaharmahal va Bakhtiari province, Iran. The total phenolic content of the ethanol extract was determined by Folin– Ciocalteu method, the antioxidant activity was evaluated by measuring 1,1-diphenyl-2-picrylhydrazyl (DPPH, and the antibacterial activity of the extracts against four bacteria, including Bacillus cereus, Listeria monocytogenes, Proteus vulgaris, and Salmonella typhimurium was determined by serial dilution assay. Results indicated that the total phenolic content in the ethanol extracts of different populations of A. hirtifolium ranged between 34 to 44 mg gallic acid/g extract. In addition, the extracts of A. hirtifolium indicated moderate– to–good inhibitory activities (MICs = 0.062 to 0.250 mg/ml against four bacteria, especially against B. cereus. The antioxidant activity of the bulbs of A. hirtifolium indicated the extract acted as an effective DPPH scavenger, but were not as effective as the BHT control. This finding suggests that the bulbs of A. hirtifolium may be considered as a natural source of antioxidants and antimicrobial agents.

  5. Association of Total Electron Content (TEC and foF2 variations with earthquake events at the anomaly crest region

    Directory of Open Access Journals (Sweden)

    A. Depueva

    2004-06-01

    Full Text Available The paper attempts to identify ionospheric parameters in association with earthquake at anomaly crest station through VHF Radio Beacon data and ground based ionosonde measurements while the Total Electron Content(TEC parameters from RB observations are based mainly on data taken over Guwahati (26.2°N, 91.75° E, foF2 data used in the analysis were collected at Ahmadabad (23.01°N, 72.36°E. The paper describes methods and techniques adopted to examine modifications on these parameters if any, due to earthquake preparatory processes at equatorial anomaly crest stations. The mechanism of inducement of density changes in the ionosphere is sought through the generation of strong fountain effect possibly by the development of electric field during the earthquake preparatory process.

  6. Earthquake Related Variation of Total Electron Content in Ionosphere over Chinese Mainland Derived from Observations of a Nationwide GNSS Network

    Science.gov (United States)

    Gan, Weijun

    2016-07-01

    Crustal Movement Observation Network of China (CMONOC) is a key national scientific infrastructure project carried out during 1997-2012 with 2 phases. The network is composed of 260 continuously observed GNSS stations (CORS) and 2081 campaign mode GNSS stations, with the main purpose to monitor the crustal movement, perceptible water vapor (PWV), total electron content (TEC), and many other tectonic and environmental elements around mainland China, by mainly using the Global Navigation Satellite System (GNSS) technology. Here, based on the GNSS data of 260 CORS of COMNOC for about 5 years, we investigated the characteristics of TEC in ionosphere over Chinese Mainland and discussed if there was any abnormal change of TEC before and after a big earthquake. our preliminary results show that it is hard to see any convincing precursor of TEC before a big earthquake. However, the huge energy released by a big earthquake can obviously disturb the TEC over meizoseismal area.

  7. The surface energy budget and interannual variation of the annual total evaporation over a highland lake in Southwest China

    Science.gov (United States)

    Feng, Jian Wu; Liu, Hui Zhi; Sun, Ji Hua; Wang, Lei

    2016-10-01

    The turbulence spectra and energy budget were investigated based on eddy covariance method over an open-water highland lake (Erhai Lake) in Southwest China. We estimated the annual total evaporation and CO2 emission from the lake, and the evaporation trend in the past few decades was also discussed. Due to the large thermal inertia of lake water, the surface water temperature lagged behind the air temperature. Maximum lake-air temperature difference of about 4 °C had been observed in November. Water temperature profile measurements revealed that the stratification of lake water was not evident throughout the year. The spectra and cospectra of wind speed and temperature roughly satisfied the -2/3 and -4/3 rule in inertial subrange, respectively. The w spectra were observed to have a larger contribution from higher frequencies than other variables. Obvious shifts of spectra and cospectra peaks toward higher frequencies were observed as the atmospheric stratification became more stable. The lake acted as a heat sink from March through June and quickly released heat into the atmosphere from September through December. Average energy balance closure for the lake was about 80 % in 2012. The lake majorly acted as a source of CO2 to the atmosphere, but weak sinks of CO2 were observed in the summer and early fall. The total annual emission of CO2 was estimated to be 333.28 g C m-2 year-1. The annual evaporation over the lake decreased due to the increased amount of low cloud and precipitation, with the lower annual evaporation in the 1990s compared to that in the 1980s.

  8. Diurnal variations of total carbon, dicarboxylic acids, ketoacids and α-dicarbonyls in aerosols in the northern vicinity of Beijing

    Science.gov (United States)

    He, N.; Kawamura, K.; Okuzawa, K.; Kanaya, Y.; Wang, Z. F.

    2013-06-01

    Aerosol samples (TSP, n=58) were collected on day- and night-time basis at Mangshan in the north of Beijing, China in autumn 2007 to better understand the status of air quality and the influence of urban pollutants in the northern vicinity of Beijing. The samples were analyzed for aerosol mass, total carbon (TC), low molecular weight α, ω-dicarboxylic acids (C2-C12), ketoacids (ωC2-ωC9, pyruvic acid), α-dicarbonyls (glyoxal and methylglyoxal), as well as aromatic (phthalic, iso- and tere-phthalic) diacids. Aerosol mass and TC concentrations are higher in daytime than in nighttime. TC/aerosol mass ratios in this study are lower than those reported in megacities in East Asia, but higher than those reported in marine aerosols. Molecular distributions of diacids demonstrated that oxalic (C2) acid was the most abundant species, comprising 38-77% of total diacids, followed by succinic (C4) and malonic (C3) acids. For most compounds, the concentrations were higher in daytime than nighttime, indicating that diacids are produced in daytime by photochemical oxidation of organic precursors emitted from anthropogenic sources in Beijing during the transport to Mangshan area by the northward wind. However, we found that C2 concentrations are higher in nighttime than in daytime. A positive correlation of C2 to glyoxylic acid (ωC2) was obtained at night when relative humidity increased up to 100%, suggesting that aqueous phase production of C2 occurs in nighttime via the oxidation of ωC2. Depletion of C2 by photolysis of Fe-oxalato complexes might be another reason for the lower concentrations of C2 in daytime samples. High phthalic acid/C4 ratios in the aerosol samples suggest that automobile combustion and coal burning products are important sources, which are subjected to photochemical oxidation during the atmospheric transport of urban aerosols from Beijing. In contrast, higher concentrations of methylglyoxal in nighttime than daytime may suggest that isoprene emitted

  9. Diurnal variations of total carbon, dicarboxylic acids, ketoacids and α-dicarbonyls in aerosols in the northern vicinity of Beijing

    Directory of Open Access Journals (Sweden)

    N. He

    2013-06-01

    Full Text Available Aerosol samples (TSP, n=58 were collected on day- and night-time basis at Mangshan in the north of Beijing, China in autumn 2007 to better understand the status of air quality and the influence of urban pollutants in the northern vicinity of Beijing. The samples were analyzed for aerosol mass, total carbon (TC, low molecular weight α, ω-dicarboxylic acids (C2-C12, ketoacids (ωC2-ωC9, pyruvic acid, α-dicarbonyls (glyoxal and methylglyoxal, as well as aromatic (phthalic, iso- and tere-phthalic diacids. Aerosol mass and TC concentrations are higher in daytime than in nighttime. TC/aerosol mass ratios in this study are lower than those reported in megacities in East Asia, but higher than those reported in marine aerosols. Molecular distributions of diacids demonstrated that oxalic (C2 acid was the most abundant species, comprising 38–77% of total diacids, followed by succinic (C4 and malonic (C3 acids. For most compounds, the concentrations were higher in daytime than nighttime, indicating that diacids are produced in daytime by photochemical oxidation of organic precursors emitted from anthropogenic sources in Beijing during the transport to Mangshan area by the northward wind. However, we found that C2 concentrations are higher in nighttime than in daytime. A positive correlation of C2 to glyoxylic acid (ωC2 was obtained at night when relative humidity increased up to 100%, suggesting that aqueous phase production of C2 occurs in nighttime via the oxidation of ωC2. Depletion of C2 by photolysis of Fe-oxalato complexes might be another reason for the lower concentrations of C2 in daytime samples. High phthalic acid/C4 ratios in the aerosol samples suggest that automobile combustion and coal burning products are important sources, which are subjected to photochemical oxidation during the atmospheric transport of urban aerosols from Beijing. In contrast, higher concentrations of methylglyoxal in nighttime than daytime may suggest that

  10. Variations of serum and mucus lysozyme activity and total protein content in the male and female Caspian kutum (Rutilus frisii kutum, Kamensky 1901) during reproductive period.

    Science.gov (United States)

    Ghafoori, Zomorod; Heidari, Behrooz; Farzadfar, Fariba; Aghamaali, Mahmoudreza

    2014-03-01

    Serum and mucus lysozyme were measured in male and female Caspian kutum (Rutilus frisii kutum) under seasonal temperature, gonadal growth and reproductive migration. Significant difference with almost similar trend in serum and mucus lysozyme of the female Caspian kutum in sampling time and ovarian growth was observed. However, while there was no significant difference in serum lysozyme of the male specimen in sampling time and testicular growth, significant variations was observed in mucus lysozyme. In addition, there was significant difference in mucus total protein both for male and female specimens. The effectiveness ratio of factors on lysozyme variations followed in descending order by seasonal temperature (main factor), reproductive activity and migration with negligible effect and the lysozyme level was not significantly different in male and female Caspian kutum.

  11. Diurnal variations of plasma homocysteine, total antioxidant status, and biological markers of muscle injury during repeated sprint: effect on performance and muscle fatigue--a pilot study.

    Science.gov (United States)

    Hammouda, Omar; Chtourou, Hamdi; Chahed, Henda; Ferchichi, Salyma; Kallel, Choumous; Miled, Abdelhedi; Chamari, Karim; Souissi, Nizar

    2011-12-01

    The aim of this study was (i) to evaluate whether homocysteine (Hcy), total antioxidant status (TAS), and biological markers of muscle injury would be affected by time of day (TOD) in football players and (ii) to establish a relationship between diurnal variation of these biomarkers and the daytime rhythm of power and muscle fatigue during repeated sprint ability (RSA) exercise. In counterbalanced order, 12 football (soccer) players performed an RSA test (5 x[6 s of maximal cycling sprint + 24 s of rest]) on two different occasions: 07:00-08:30 h and 17:00-18:30 h. Fasting blood samples were collected from a forearm vein before and 3-5 min after each RSA test. Core temperature, rating of perceived exertion, and performances (i.e., Sprint 1, Sprint 2, and power decrease) during the RSA test were significantly higher at 17:00 than 07:00 h (p RSA test. However, biomarkers of antioxidant status' resting levels (i.e., total antioxidant status, uric acid, and total bilirubin) were higher in the morning. This TOD effect was suppressed after exercise for TAS and uric acid. In conclusion, the present study confirms diurnal variation of Hcy, selected biological markers of cellular damage, and antioxidant status in young football players. Also, the higher performances and muscle fatigue showed in the evening during RSA exercise might be due to higher levels of biological markers of muscle injury and lower antioxidant status at this TOD.

  12. NO 2 column amount and total ozone in Stara Zagora (42°N, 25°E) and their response to the solar rotational activity variation

    Science.gov (United States)

    Werner, R.; Kostadinov, I.; Valev, D.; Hempelmann, A.; Atanassov, At.; Giovanelli, G.; Petritoli, A.; Bortoli, D.; Ravegnani, F.; Markova, T.

    Studies have shown that the total ozone amount and the ozone mixing ratio on the Earth's equator correlate with the 27-day rotational modulation of the solar activity.We report some first results of our research, concerning possible links between the short-term solar activity, i.e., variations on the rotational time-scale, and the stratospheric NO 2. The solar activity variations and the atmospheric responses were studied by means of wavelet analysis, cross-correlation and cross-wavelet analysis. It is found out that the 27-day solar cycle in the UV irradiation is modulated by a longer period of several months; this longer period is probably related with active region growth and decay (ARGD). That kind of modulation produces shortening or extension of the 27-day basic period, ranging from 22 to 34 days. The modulation is a consequence of ARGD and hence, results from a variable pattern of spots and active regions on the solar surface. We find a similar time-frequency behaviour in the wavelet maps of NO 2 slant column amounts, derived from DOAS measurements at the Stara Zagora station as well as in the total ozone amount, obtained by the GOME instrument during solar cycle 23. For those time intervals when the cross-correlation between the variation of the short-term solar activity and that of the trace gas species is positive, the cross-correlation coefficients are up to 0.6 for the NO 2 and up to 0.5 for the ozone variation.

  13. Seasonal variation in the chemical composition, antioxidant activity, and total phenolic content of Artemisia absinthium essential oils

    Directory of Open Access Journals (Sweden)

    A Mohammadi

    2015-01-01

    Full Text Available Background: The genus Artemisia belonging to the Compositae (Asteraceae family and many traditional uses from the Artemisia species were reported. Artemisia absinthium is one of the species in this genus and commonly used in the food industry in the preparation of aperitifs, bitters, and spirits. Objective: Evaluation of the effect of different harvesting stages on the composition of essential oil and antioxidant capacity of A. absinthium. Materials and Methods: Essential oils from the aerial parts of A. absinthium, collected in three stages (preflowering, flowering, and after-flowering from plants grown in the North Khorasan province of Iran were obtained by steam distillation and the chemical composition of the oils was analyzed by gas chromatography-mass spectrometry and antioxidant activity and total phenolic content were determined by 2-diphenyl-1-picrylhydrazyl assay and Folin-Ciocalteu method. Results: Analysis of the isolated oils revealed the presence of 44 compounds, mainly alpha-pinene, sabinene, beta-pinene, alpha-phellandrene, p-cymene and chamazulene. Alpha-phellandrene, and chamazulene were major compounds in preflowering stage, but beta-pinene and alpha-phellandrene were major in flowering and past-flowering stages. Flowering stage had highest yield and after flowering stage had lowest yield. The essential oil of preflowering stage had the highest amount of antioxidant compound (chamazulene. Preflowering stage with highest amount of phenolic compounds had the strongest antioxidant activity with the lowest amount of EC 50 . Conclusion: This study showed that the harvesting stage had significant effects on chemical composition and antioxidant properties of essential oils, and chamazulene is main compound for antioxidant activity in A. absinthium.

  14. Monthly and seasonal variation in the amount of total lipid and fatty acid in the muscle of a silurid cat fish Wallagu attu

    Directory of Open Access Journals (Sweden)

    Pinak Dutta

    2014-09-01

    Full Text Available Monthly and seasonal variation in the amount of total lipid and fatty acid in the muscle tissues of W. attu growing wild in large ponds was studied. The result depicts that both the amounts of total lipid and fatty acid varied monthly and thus seasonally in this fish species (boal belonging to the family of fresh water silurid cat fishes. The percentage of total lipid value reaches its minimum in May and starts increasing from June to October. During breeding season the amount of total fatty acid also shows the same tendency to decrease till May when it reaches its minimum. From June onwards the total fatty acid increases significantly. At the end of the reproductive season, i.e. during the commencement of the nutritional season, the fishes start the process of storing energy in the form of lipids / fatty acids for future use i.e. during reproduction season or during scarcity of food. This is what is reflected in the study that, during the monsoon months in West Bengal the lipid / fatty acid content in the muscle tissues of boal rises to the maximum. This starts decreasing in the winter season as the reproduction period approaches and reaches its minimum in summer.

  15. Robust dynamic myocardial perfusion CT deconvolution for accurate residue function estimation via adaptive-weighted tensor total variation regularization: a preclinical study

    Science.gov (United States)

    Zeng, Dong; Gong, Changfei; Bian, Zhaoying; Huang, Jing; Zhang, Xinyu; Zhang, Hua; Lu, Lijun; Niu, Shanzhou; Zhang, Zhang; Liang, Zhengrong; Feng, Qianjin; Chen, Wufan; Ma, Jianhua

    2016-11-01

    Dynamic myocardial perfusion computed tomography (MPCT) is a promising technique for quick diagnosis and risk stratification of coronary artery disease. However, one major drawback of dynamic MPCT imaging is the heavy radiation dose to patients due to its dynamic image acquisition protocol. In this work, to address this issue, we present a robust dynamic MPCT deconvolution algorithm via adaptive-weighted tensor total variation (AwTTV) regularization for accurate residue function estimation with low-mA s data acquisitions. For simplicity, the presented method is termed ‘MPD-AwTTV’. More specifically, the gains of the AwTTV regularization over the original tensor total variation regularization are from the anisotropic edge property of the sequential MPCT images. To minimize the associative objective function we propose an efficient iterative optimization strategy with fast convergence rate in the framework of an iterative shrinkage/thresholding algorithm. We validate and evaluate the presented algorithm using both digital XCAT phantom and preclinical porcine data. The preliminary experimental results have demonstrated that the presented MPD-AwTTV deconvolution algorithm can achieve remarkable gains in noise-induced artifact suppression, edge detail preservation, and accurate flow-scaled residue function and MPHM estimation as compared with the other existing deconvolution algorithms in digital phantom studies, and similar gains can be obtained in the porcine data experiment.

  16. Double-Difference Waveform Inversion with a Modified Total-Variation Regularization Scheme: Application to Time-Lapse Walkaway VSP Data

    Science.gov (United States)

    Lin, Y.; Huang, L.

    2014-12-01

    Quantifying reservoir changes is crucial for safe and long-term geologic carbon storage. We develop a new double-difference waveform inversion method with a modified total-variation regularization scheme to jointly invert time-lapse seismic data for geophysical properties changes in reservoirs/target monitoring regions. Our new method avoids the non-differentiability of the total-variation regularization scheme, and improves the robustness of waveform inversion. We use time-lapse seismic data for joint inversion to reduce inversion artifacts outside target monitoring regions. Two walkaway vertical seismic profiling (VSP) datasets were acquired at the SACROC enhanced-oil-recovery (EOR) field in Texas in 2008 and 2009 for monitoring CO2 injection and migration. We apply our new double-difference waveform inversion method to the SACROC time-lapse VSP datasets. Our joint inversion result reveals a region with seismic-wave velocities lower than the other regions in the reservoir. This velocity decrease is caused by CO2 injection and migration.

  17. Groundwater, Soil Moisture, Snow Water Equivalent, and River Water in the Seasonal Variation of Total Terrestrial Water Storage in Major River Basins

    Science.gov (United States)

    Oki, T.; Yoshimura, K.; Kim, H.; Shen, Y.; Thanh, N. D.; Seto, S.; Kanae, S.

    2006-12-01

    Both the combined atmospheric-river basin water balance and the remote sensing by GRACE can estimate the variation of the total terrestrial water storage which consist the changes in ground water, soil moisture, snow water equivalent, and water in rivers, lakes, ponds, etc. What are the major components in the change of the total terrestrial water storage? One hand, the seasonal variation of the total water storage in major continental-scale river basins are estimated by the atmospheric-river basin water balance (AWB) method The global distribution of water vapor flux convergence was estimated using the ECMWF global analysis data for the period from 1986 through 1995. The 10 year mean value of the atmospheric water vapor convergence was adjusted to match with the climatological mean value of river runoff for 1961-1990. Then the seasonal changes of the total terrestrial water storage were estimated by AWB method combining the atmospheric water vapor convergence for major river basins and the runoff from the area. On the other hand, the components in the change of the total terrestrial water storage were investigated using the multi-model products forced by observed surface meteorology. Under the Global Land/Atmosphere Study (GLASS), the Phase 2 of the Global Soil Wetness Project (GSWP-2) produced the first global (excluding Antarctica) 1x1 degree Multi-Model Analysis (MMA) of land-surface variables and fluxes for the 10-year period of 1986 1995 at the daily time scale. Thirteen land-surface models (LSMs) were driven by the best possible forcing data of the atmospheric conditions, such as precipitation, downward radiation, wind speed, air humidity and air temperature with temporal resolution of 3-hourly or higher. Water balance in major continental scale river basins were post-processed and the seasonal changes in ground water, soil moisture, snow water equivalent, and the water in river channel were analyzed using the Total Runoff Integrating Pathways (TRIP) and a

  18. Temporal and spatial variation of hardness and total dissolved solids concentration in drinking water resources of Ilam City using Geographic Information System

    Directory of Open Access Journals (Sweden)

    Zabihollah Yousefi

    2015-12-01

    Full Text Available Background: In recent times, the decreasing groundwater reserves due to over-consumption of water resources and the unprecedented reduction of precipitation, during the past 1 decades, have resulted in a change in the volume and quality of water with time. The aim of this study was to determine the spatial and temporal variations of hardness and total dissolved solids in drinking water resources of Ilam city, using the GIS system. Methods: This cross-sectional study was carried out on 20 sources of drinking water in Ilam and the results of 5 years archived by the Water and Sewage Co were analyzed using geographic information system (GIS software version 9.3, SPSS version 16 and one-way analysis of variance (ANOVA. The sampling and measurement were also performed in this study based on the Standard Method book. Results: The ordinary kriging method and spherical model are the best interpolation methods for hardness and total dissolved solid, due to the normal distribution of data. The highest values of parameters in most cases are related to the western parts based on maps. The one-way ANOVA test showed that the average amount of total hardness (P = 0.68 and total dissolved solids (P = 0.6 in different seasons of the year are the same. Conclusion: Overuse of groundwater due to illegal digging and permanent easy access to water, increased the salinity of water in the central sections of the studied area. Proper planning that allows the withdrawal of water from authorized underground aquifers or water supply from surface water or dams should be done to overcome this problem.

  19. Variação do potencial total da água em uma toposseqüência de solos de tabuleiro, durante dois anos Total water potential variation in a soil table land topsequence, during two years

    Directory of Open Access Journals (Sweden)

    Luciano da Silva Souza

    2001-02-01

    Full Text Available O trabalho teve como objetivo avaliar quinzenalmente, em 1996 e 1997, a variação do potencial total da água ao longo do tempo, em solos de uma toposseqüência de tabuleiro localizada em Sapeaçu, BA. Esta toposseqüência tinha as seguintes características: a comprimento de 190 m; b declividade média de 0,097 m m-1; c cultivo com laranja; d Latossolo Amarelo argissólico coeso, no terço superior; e Argissolo Amarelo coeso, no terço médio; f Argissolo Acinzentado não coeso, no terço inferior. A umidade do solo foi medida com sonda de nêutrons, nas profundidades de 0,30, 0,70, 1,10 e 1,50 m. Com base nas respectivas curvas de retenção, obteve-se o potencial matricial e, em seguida, o potencial total da água, para cada solo, profundidade e tempo. A camada coesa dificulta o fluxo de água no solo, tanto no processo de molhamento como no de secamento. Em conseqüência, o potencial total da água em solos com camada coesa varia bruscamente na camada mais superficial, ao longo do tempo, e mais lentamente nas camadas mais profundas. Em solo não coeso, a variação brusca do potencial ocorre apenas na camada mais superficial. O limite de tensão de água no solo de -1.500 kPa como sendo o ponto de murchamento permanente não se aplica à cultura dos citros.The objective of this work was to evaluate, fortnightly, during 1996/1997, the total soil water potential variation in a tableland topsequence in Sapeaçu county, BA, Brazil. This topsequence had the following characteristics: a length of 190 m; b slope of 0.097 m m-1; c orange as growing crop; d the upper third with a cohesive argisolic Yellow Latosol; e the middle third with a cohesive Yellow Argisol; and f the lower third with a non-cohesive Gray Argisol. Soil water was estimated by neutron probe at depths of0.30, 0.70, 1.10, and 1.50 m. Based on water retention curves, matric potential and, in sequence, total soil water potential were determined, for each soil and depth in

  20. Validation of a simple radiographic method to determine variations in pelvic and acetabular cup sagittal plane alignment after total hip arthroplasty

    Energy Technology Data Exchange (ETDEWEB)

    Shon, Won Yong; Hur, Chang Yong; Jajodia, Nirmal [Korea University College of Medicine, Guro Hospital, Department of Orthopedics, Seoul (Korea); Gupta, Siddhartha; Biswal, Sandeep; Hong, Suk Joo; Myung, Jae Sung [Korea University College of Medicine, Guro Hospital, Department of Radiology, Seoul (Korea)

    2008-12-15

    Orientation of acetabular component, influenced by pelvic tilt, body position, and individual variations affects the outcome following total hip arthroplasty (THA). Currently available methods of evaluation are either imprecise or require advanced image processing. We analyzed intersubject and intrasubject variability of pelvic tilt, measured by sagittal sacral tilt (ST) and its relationship with acetabular component tilt (AT) by using a simple method based on standard radiographs. ST was measured on lateral radiographs of pelvis including lumbosacral spine obtained in supine, sitting, standing, and lateral decubitus position for 40 asymptomatic THA patients and compared to computed tomography (CT) data obtained in supine position. AT was measured on lateral radiographs (measured acetabular tilt: MAT) in each position and compared to measurement of AT on CT and an indirectly calculated AT (CAT). Mean ST changed from supine to sitting, standing, and lateral decubitus positions as follows: 26.5 {+-} 15.5 (range 4.6-73.4 ), 8.4{+-}6.2 (range 0.6-24.5 ), and 13.4{+-}8.4 (range 0.1-24.2 ; p<0.0001, p=0.002, p=0.006). The MAT on radiographs was not significantly different from the MAT measured on CT (p=0.002) and the CAT (p=0.06). There is a good correlation between change in ST and MAT in sagittal plane (r=0.93). Measurement of ST on radiographs is a simple and reliable method to track changes in pelvic tilt in different body positions. There is significant intersubject and intrasubject variation of ST and MAT with postural changes and it may explain causes of impingement or instability following THA, which could not be previously explained. (orig.)

  1. Accelerated echo planar J-resolved spectroscopic imaging in prostate cancer: a pilot validation of non-linear reconstruction using total variation and maximum entropy.

    Science.gov (United States)

    Nagarajan, Rajakumar; Iqbal, Zohaib; Burns, Brian; Wilson, Neil E; Sarma, Manoj K; Margolis, Daniel A; Reiter, Robert E; Raman, Steven S; Thomas, M Albert

    2015-11-01

    The overlap of metabolites is a major limitation in one-dimensional (1D) spectral-based single-voxel MRS and multivoxel-based MRSI. By combining echo planar spectroscopic imaging (EPSI) with a two-dimensional (2D) J-resolved spectroscopic (JPRESS) sequence, 2D spectra can be recorded in multiple locations in a single slice of prostate using four-dimensional (4D) echo planar J-resolved spectroscopic imaging (EP-JRESI). The goal of the present work was to validate two different non-linear reconstruction methods independently using compressed sensing-based 4D EP-JRESI in prostate cancer (PCa): maximum entropy (MaxEnt) and total variation (TV). Twenty-two patients with PCa with a mean age of 63.8 years (range, 46-79 years) were investigated in this study. A 4D non-uniformly undersampled (NUS) EP-JRESI sequence was implemented on a Siemens 3-T MRI scanner. The NUS data were reconstructed using two non-linear reconstruction methods, namely MaxEnt and TV. Using both TV and MaxEnt reconstruction methods, the following observations were made in cancerous compared with non-cancerous locations: (i) higher mean (choline + creatine)/citrate metabolite ratios; (ii) increased levels of (choline + creatine)/spermine and (choline + creatine)/myo-inositol; and (iii) decreased levels of (choline + creatine)/(glutamine + glutamate). We have shown that it is possible to accelerate the 4D EP-JRESI sequence by four times and that the data can be reliably reconstructed using the TV and MaxEnt methods. The total acquisition duration was less than 13 min and we were able to detect and quantify several metabolites.

  2. Implementation of a fully 3D system model for brain SPECT with fan- beam-collimator OSEM reconstruction with 3D total variation regularization

    Science.gov (United States)

    Ye, Hongwei; Krol, Andrzej; Lipson, Edward D.; Lu, Yao; Xu, Yuesheng; Lee, Wei; Feiglin, David H.

    2007-03-01

    In order to improve tomographically reconstructed image quality, we have implemented a fully 3D reconstruction, using an ordered subsets expectation maximization (OSEM) algorithm for fan-beam collimator (FBC) SPECT, along with a volumetric system model-fan-volume system model (FVSM), a modified attenuation compensation, a 3D depth- and angle-dependent resolution and sensitivity correction, and a 3D total variation (TV) regularization. SPECT data were acquired in a 128x64 matrix, in 120 views with a circular orbit. The numerical Zubal brain phantom was used to simulate a FBC HMPAO Tc-99m brain SPECT scan, and a low noise and scatter-free projection dataset was obtained using the SimSET Monte Carlo package. A SPECT scan for a mini-Defrise phantom and brain HMPAO SPECT scans for five patients were acquired with a triple-head gamma camera (Triad 88) equipped with a low-energy high-resolution (LEHR) FBC. The reconstructed images, obtained using clinical filtered back projection (FBP), OSEM with a line-length system model (LLSM) and 3D TV regularization, and OSEM with FVSM and 3D TV regularization were quantitatively studied. Overall improvement in the image quality has been observed, including better axial and transaxial resolution, better integral uniformity, higher contrast-to-noise ration between the gray matter and the white matter, and better accuracy and lower bias in OSEM-FVSM, compared with OSEM-LLSM and clinical FBP.

  3. Low-dose dynamic myocardial perfusion CT image reconstruction using pre-contrast normal-dose CT scan induced structure tensor total variation regularization

    Science.gov (United States)

    Gong, Changfei; Han, Ce; Gan, Guanghui; Deng, Zhenxiang; Zhou, Yongqiang; Yi, Jinling; Zheng, Xiaomin; Xie, Congying; Jin, Xiance

    2017-04-01

    Dynamic myocardial perfusion CT (DMP-CT) imaging provides quantitative functional information for diagnosis and risk stratification of coronary artery disease by calculating myocardial perfusion hemodynamic parameter (MPHP) maps. However, the level of radiation delivered by dynamic sequential scan protocol can be potentially high. The purpose of this work is to develop a pre-contrast normal-dose scan induced structure tensor total variation regularization based on the penalized weighted least-squares (PWLS) criteria to improve the image quality of DMP-CT with a low-mAs CT acquisition. For simplicity, the present approach was termed as ‘PWLS-ndiSTV’. Specifically, the ndiSTV regularization takes into account the spatial-temporal structure information of DMP-CT data and further exploits the higher order derivatives of the objective images to enhance denoising performance. Subsequently, an effective optimization algorithm based on the split-Bregman approach was adopted to minimize the associative objective function. Evaluations with modified dynamic XCAT phantom and preclinical porcine datasets have demonstrated that the proposed PWLS-ndiSTV approach can achieve promising gains over other existing approaches in terms of noise-induced artifacts mitigation, edge details preservation, and accurate MPHP maps calculation.

  4. Total electron content variations over southern Europe before and during the M 6.3 Abruzzo earthquake of April 6, 2009

    Directory of Open Access Journals (Sweden)

    Spyrous D. Spatalas

    2012-04-01

    Full Text Available

    Total electron content (TEC data of 14 global positioning system (GPS stations of the EUREF network were provided by the IONOLAB. These were analyzed using wavelet analysis and discrete Fourier analysis to investigate the TEC variations over southern Europe in the month before the catastrophic Abruzzo earthquake of M 6.3 of April 6, 2009. The main conclusions of this analysis are: (a TEC oscillations in a broad range of frequencies occurred randomly over a broad area of several hundred kilometers from the earthquake; (b Morning and evening extensions of the day-time TEC values were seen for all of the EUREF stations of this program shortly before, during and shortly after the main earthquake period; (c High frequency oscillations (f $ 0.0003 Hz, period T $ 60 m appear to indicate the location of the earthquake, although with questionable accuracy, while the fractal characteristics of the frequency distribution indicates the locus of the earthquake with relatively greater accuracy. We conclude that the lithosphere-atmosphere-ionosphere coupling mechanism through acoustic or gravity waves might explain this phenomenology.

  5. 基于小波包分解的整体变分去噪算法%Total variation algorithm of image denoising based on wavelet packet decomposition

    Institute of Scientific and Technical Information of China (English)

    唐昌令; 彭国华

    2013-01-01

    由Rudin等人提出的整体变分(TV)模型被认为是目前最好的图像去噪模型之一.理论表明,TV模型对分块常量的图像去噪效果显著.对于纹理细节丰富的图像,通过引入小波包分解技术,对图像的纹理细节进行多层小波包分解,得到一系列近似分块常量的子图像,用TV模型对子图像分别进行处理,从而图像的纹理细节得到了更好的保留.相对于单独使用TV模型去噪,该方法得到的复原图像峰值信噪比(PSNR)提高了1 dB左右.同时由于采用改进的Bregman迭代方案求解TV模型,算法收敛时间得到了极大的减少.%The Total Variation(TV) model of Rudin et al. for image denoising is considered as one of the best denoising models. Theory suggests that the TV model denoises well piecewise constant images. For the texture rich image, in this paper, it is decomposed by multi-wavelet packet into a series of approximate piecewise constant sub-images. Sub-images are processed separately by TV model. Thus, the texture detail of image is preserved better and the Peak Signal to Noise Ratio (PSNR) of denoised image is improved 1 dB, compared with using TV model alone. At the same time, the improved Bregman iteration scheme is adopted to solve TV model. The algorithm convergence time has been greatly decreased.

  6. Relationship among specific bacterial counts and total bacterial and somatic cell counts and factors influencing their variation in ovine bulk tank milk.

    Science.gov (United States)

    de Garnica, M L; Linage, B; Carriedo, J A; De La Fuente, L F; García-Jimeno, M C; Santos, J A; Gonzalo, C

    2013-02-01

    To analyze the relationship among the counts of different organisms and total bacterial count (BTTBC) and somatic cell count (BTSCC) as determined in dairy laboratories in ovine bulk tank milk, 751 bulk tank milk samples from 205 dairy sheep flocks belonging to Consortium for Ovine Promotion (CPO) were collected between January and December 2011. Four samplings were carried out in each flock, once per season, throughout 1 yr. Variables analyzed were bulk tank counts of thermoduric, psychrotrophic, coliform, and gram-positive catalase-negative cocci (GPCNC) bacterial groups. Thermoduric, psychrotrophic, and coliform species were significantly related to BTTBC, whereas GPCNC were correlated with both BTTBC and BTSCC variables. Highest counts were for psychrotroph and coliform groups, and a moderate to high correlation (r=0.51) was found between both variables, indicating that poor cleaning practices in the flocks tend to select for less-resistant organisms, such as gram-negative rods. In addition, BTTBC correlated with BTSCC (r=0.42). Some variation factors for specific bacterial counts, such as breed, season, milking type, dry therapy, and milk yield, were also analyzed. Flock information was collected from flock books, annual audits, and the CPO traceability system. Psychrotrophs and coliforms had elevated counts in winter, whereas GPCNC were higher in summer and in hand-milked flocks. Dry therapy contributed to the reduction in psychrotrophic bacteria; therefore, some strains of mammary pathogens could also be psychrotrophic bacteria. Results of this study would be helpful for troubleshooting milk quality problems and developing premium payment systems in dairy sheep.

  7. Blurred Face Image Recovery Algorithm Based on Total Variation%基于全变分的模糊人脸图像复原算法

    Institute of Scientific and Technical Information of China (English)

    魏雪飞; 葛成伟

    2013-01-01

    Face image was always affected by many factors,then its quality was degraded during the acquisition process,so image recovery from blurred images to clear images became one of the hot spots of the image processing domain.Based on the total variational regularization algorithm,by introduction of point sets to cluster,and with some auxiliary constraints,this paper puts forward an optimization constraint model of face image recovery,which is iteratived by steepest descent method,to make the blurred face images clear.The experimental results demonstrate that it is feasible for this model by adjusting the parameters,and it recovers the original image substantially.%在人脸图像采集过程中,会受到多种因素影响,图像质量都会有所退化,因此将模糊图像恢复成清晰图像一直是图像处理领域的热点之一.根据全变分正则化的图像复原算法的思想,引入相容点集与不相容点集的概念,以及一些辅助的约束条件,提出一种有约束人脸图像复原优化模型,并使用最速下降法求解此模型,使模糊的人脸图像清晰化.实验结果表明,这种模型是可行的,基本恢复了原始的图像.

  8. Contrast adaptive total p-norm variation minimization approach to CT reconstruction for artifact reduction in reduced-view brain perfusion CT

    Science.gov (United States)

    Kim, Chang-Won; Kim, Jong-Hyo

    2011-03-01

    Perfusion CT (PCT) examinations are getting more frequently used for diagnosis of acute brain diseases such as hemorrhage and infarction, because the functional map images it produces such as regional cerebral blood flow (rCBF), regional cerebral blood volume (rCBV), and mean transit time (MTT) may provide critical information in the emergency work-up of patient care. However, a typical PCT scans the same slices several tens of times after injection of contrast agent, which leads to much increased radiation dose and is inevitability of growing concern for radiation-induced cancer risk. Reducing the number of views in projection in combination of TV minimization reconstruction technique is being regarded as an option for radiation reduction. However, reconstruction artifacts due to insufficient number of X-ray projections become problematic especially when high contrast enhancement signals are present or patient's motion occurred. In this study, we present a novel reconstruction technique using contrast-adaptive TpV minimization that can reduce reconstruction artifacts effectively by using different p-norms in high contrast and low contrast objects. In the proposed method, high contrast components are first reconstructed using thresholded projection data and low p-norm total variation to reflect sparseness in both projection and reconstruction spaces. Next, projection data are modified to contain only low contrast objects by creating projection data of reconstructed high contrast components and subtracting them from original projection data. Then, the low contrast projection data are reconstructed by using relatively high p-norm TV minimization technique, and are combined with the reconstructed high contrast component images to produce final reconstructed images. The proposed algorithm was applied to numerical phantom and a clinical data set of brain PCT exam, and the resultant images were compared with those using filtered back projection (FBP) and conventional TV

  9. Magnetic Resonance Materials in Physics, Biology and Medicine Fast Reduction of Undersampling Artifacts in Radial MR Angiography with 3D Total Variation on Graphics Hardware

    Science.gov (United States)

    Knoll, Florian; Unger, Markus; Diwoky, Clemens; Clason, Christian; Pock, Thomas; Stollberger, Rudolf

    2014-01-01

    Objective Subsampling of radially encoded MRI acquisitions in combination with sparsity promoting methods opened a door to significantly increased imaging speed, which is crucial for many important clinical applications. In particular, it has been shown recently that total variation (TV) regularization efficiently reduces undersampling artifacts. The drawback of the method is the long reconstruction time which makes it impossible to use in daily clinical practice, especially if the TV optimization problem has to be solved repeatedly to select a proper regularization parameter. Materials and Methods The goal of this work was to show that for the case of MR-Angiography, TV filtering can be performed as a post-processing step, in contrast to the common approach of integrating TV penalties in the image reconstruction process. With this approach it is possible to use TV algorithms with data fidelity terms in image space, which can be implemented very efficiently on graphic processing units (GPUs). The combination of a special radial sampling trajectory and a full 3D formulation of the TV minimization problem is crucial for the effectiveness of the artifact elimination process. Results and Conclusion The computation times of GPU-TV show that interactive elimination of undersampling artifacts is possible even for large volume data sets, in particular allowing the interactive determination of the regularization parameter. Results from phantom measurements and in vivo angiography data sets show that 3D TV, together with the proposed sampling trajectory, leads to pronounced improvements in image quality. However, while artifact removal was very efficient for angiography data sets in this work, it cannot be expected that the proposed method of TV post-processing will work for arbitrary types of scans. PMID:20352289

  10. WE-EF-207-08: Improve Cone Beam CT Using a Synchronized Moving Grid, An Inter-Projection Sensor Fusion and a Probability Total Variation Reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, H; Kong, V; Jin, J [Georgia Regents University Cancer Center, Augusta, GA (Georgia); Ren, L; Zhang, Y; Giles, W [Duke University Medical Center, Durham, NC (United States)

    2015-06-15

    Purpose: To present a cone beam computed tomography (CBCT) system, which uses a synchronized moving grid (SMOG) to reduce and correct scatter, an inter-projection sensor fusion (IPSF) algorithm to estimate the missing information blocked by the grid, and a probability total variation (pTV) algorithm to reconstruct the CBCT image. Methods: A prototype SMOG-equipped CBCT system was developed, and was used to acquire gridded projections with complimentary grid patterns in two neighboring projections. Scatter was reduced by the grid, and the remaining scatter was corrected by measuring it under the grid. An IPSF algorithm was used to estimate the missing information in a projection from data in its 2 neighboring projections. Feldkamp-Davis-Kress (FDK) algorithm was used to reconstruct the initial CBCT image using projections after IPSF processing for pTV. A probability map was generated depending on the confidence of estimation in IPSF for the regions of missing data and penumbra. pTV was finally used to reconstruct the CBCT image for a Catphan, and was compared to conventional CBCT image without using SMOG, images without using IPSF (SMOG + FDK and SMOG + mask-TV), and image without using pTV (SMOG + IPSF + FDK). Results: The conventional CBCT without using SMOG shows apparent scatter-induced cup artifacts. The approaches with SMOG but without IPSF show severe (SMOG + FDK) or additional (SMOG + TV) artifacts, possibly due to using projections of missing data. The 2 approaches with SMOG + IPSF removes the cup artifacts, and the pTV approach is superior than the FDK by substantially reducing the noise. Using the SMOG also reduces half of the imaging dose. Conclusion: The proposed technique is promising in improving CBCT image quality while reducing imaging dose.

  11. Dose optimization with first-order total-variation minimization for dense angularly sampled and sparse intensity modulated radiation therapy (DASSIM-RT).

    Science.gov (United States)

    Kim, Hojin; Li, Ruijiang; Lee, Rena; Goldstein, Thomas; Boyd, Stephen; Candes, Emmanuel; Xing, Lei

    2012-07-01

    A new treatment scheme coined as dense angularly sampled and sparse intensity modulated radiation therapy (DASSIM-RT) has recently been proposed to bridge the gap between IMRT and VMAT. By increasing the angular sampling of radiation beams while eliminating dispensable segments of the incident fields, DASSIM-RT is capable of providing improved conformity in dose distributions while maintaining high delivery efficiency. The fact that DASSIM-RT utilizes a large number of incident beams represents a major computational challenge for the clinical applications of this powerful treatment scheme. The purpose of this work is to provide a practical solution to the DASSIM-RT inverse planning problem. The inverse planning problem is formulated as a fluence-map optimization problem with total-variation (TV) minimization. A newly released L1-solver, template for first-order conic solver (TFOCS), was adopted in this work. TFOCS achieves faster convergence with less memory usage as compared with conventional quadratic programming (QP) for the TV form through the effective use of conic forms, dual-variable updates, and optimal first-order approaches. As such, it is tailored to specifically address the computational challenges of large-scale optimization in DASSIM-RT inverse planning. Two clinical cases (a prostate and a head and neck case) are used to evaluate the effectiveness and efficiency of the proposed planning technique. DASSIM-RT plans with 15 and 30 beams are compared with conventional IMRT plans with 7 beams in terms of plan quality and delivery efficiency, which are quantified by conformation number (CN), the total number of segments and modulation index, respectively. For optimization efficiency, the QP-based approach was compared with the proposed algorithm for the DASSIM-RT plans with 15 beams for both cases. Plan quality improves with an increasing number of incident beams, while the total number of segments is maintained to be about the same in both cases. For the

  12. Comparison of direct and indirect estimates of apparent total tract digestibility in swine with effort to reduce variation by pooling of multiple day fecal samples.

    Science.gov (United States)

    Jang, Y D; Lindemann, M D; Agudelo-Trujillo, J H; Escobar, C S; Kerr, B J; Inocencio, N; Cromwell, G L

    2014-10-01

    The intent of this study was to establish a fecal sampling procedure for the indicator method (IM) to provide digestibility values similar to those obtained by the total collection (TC) method. A total of 24 pigs (52.6 ± 1.5 kg) were fed 1 of 4 diets with a 2 × 2 factorial arrangement of virginiamycin and phytase (PHY) added to a corn-soybean meal diet with no inorganic P supplement. Pigs were housed in metabolism crates for a 5-d TC period after 7 d of adaptation. Immediately after the TC, a fecal collection period followed, using the IM by including 0.25% of Cr2O3 in the feed for 10 d. Fecal collection for the IM started the day after diets containing Cr2O3 were first fed, and continued for 9 consecutive days with a single grab sample per day. Similar portions of feces from d 5 to 9 were also composited into 4 samples to evaluate multi-day pooling combinations. Highly variable means and CV among samples for apparent total tract digestibility (ATTD) were observed at d 1 and 2 using the IM. The mean ATTD for DM, GE, and nutrients appeared to be stabilized by d 5 or 6 in all dietary treatments. The TC data seemed to have lower CV than the IM data for many components. Based on the linear broken-line analysis, fecal Cr concentration plateaued at d 3.75 (P < 0.001) after the first feeding of Cr. Mean ATTD values by the IM were lower than those by the TC method for DM (P < 0.05), GE (P < 0.01), P (P < 0.01), and Ca (P < 0.001). The PHY supplementation improved ATTD of P (P < 0.001) and Ca (P < 0.001) in both collection methods, whereas the PHY effect on ATTD of DM was observed only for the IM (P < 0.05). Differences related to PHY effect on ATTD were detected from d 4 to 9 in a single grab sample for P and DM but the ATTD of DM had inconsistent P-values by day. Fecal sampling after 4 d of initial feeding of marker always allowed detection of treatment effects on ATTD of P but not on ATTD of DM. Results indicated that the IM results in lower digestibility values than

  13. Beam’s-eye-view dosimetrics (BEVD) guided rotational station parameter optimized radiation therapy (SPORT) planning based on reweighted total-variation minimization

    Science.gov (United States)

    Kim, Hojin; Li, Ruijiang; Lee, Rena; Xing, Lei

    2015-03-01

    Conventional VMAT optimizes aperture shapes and weights at uniformly sampled stations, which is a generalization of the concept of a control point. Recently, rotational station parameter optimized radiation therapy (SPORT) has been proposed to improve the plan quality by inserting beams to the regions that demand additional intensity modulations, thus formulating non-uniform beam sampling. This work presents a new rotational SPORT planning strategy based on reweighted total-variation (TV) minimization (min.), using beam’s-eye-view dosimetrics (BEVD) guided beam selection. The convex programming based reweighted TV min. assures the simplified fluence-map, which facilitates single-aperture selection at each station for single-arc delivery. For the rotational arc treatment planning and non-uniform beam angle setting, the mathematical model needs to be modified by additional penalty term describing the fluence-map similarity and by determination of appropriate angular weighting factors. The proposed algorithm with additional penalty term is capable of achieving more efficient and deliverable plans adaptive to the conventional VMAT and SPORT planning schemes by reducing the dose delivery time about 5 to 10 s in three clinical cases (one prostate and two head-and-neck (HN) cases with a single and multiple targets). The BEVD guided beam selection provides effective and yet easy calculating methodology to select angles for denser, non-uniform angular sampling in SPORT planning. Our BEVD guided SPORT treatment schemes improve the dose sparing to femoral heads in the prostate and brainstem, parotid glands and oral cavity in the two HN cases, where the mean dose reduction of those organs ranges from 0.5 to 2.5 Gy. Also, it increases the conformation number assessing the dose conformity to the target from 0.84, 0.75 and 0.74 to 0.86, 0.79 and 0.80 in the prostate and two HN cases, while preserving the delivery efficiency, relative to conventional single-arc VMAT plans.

  14. Variation trends and influencing factors of total gaseous mercury in the Pearl River Delta-A highly industrialised region in South China influenced by seasonal monsoons

    Science.gov (United States)

    Chen, Laiguo; Liu, Ming; Xu, Zhencheng; Fan, Ruifang; Tao, Jun; Chen, Duohong; Zhang, Deqiang; Xie, Donghai; Sun, Jiaren

    2013-10-01

    Studies on atmospheric mercury in the Pearl River Delta (PRD) region are important because of the economic relevance of this region to China, because of its economic developmental pattern and because it is a highly industrialised area influenced by the strong seasonal monsoons. Total gaseous mercury (TGM), meteorological parameters and criteria pollutant concentrations were measured at Mt. Dinghu (DH, a regional monitoring site) and Guangzhou (GZ, an urban monitoring site) in the PRD region from October 2009 to April 2010 and from November 2010 to November 2011, respectively. The ranges of daily average TGM concentrations at the DH and GZ sites were 1.87-29.9 ng m-3 (5.07 ± 2.89 ng m-3) and 2.66-11.1 ng m-3 (4.60 ± 1.36 ng m-3), respectively, which were far more significant than the background values in the Northern Hemisphere (1.5-1.7 ng m-3), suggesting that the atmosphere in the PRD has suffered from mercury pollution. Similar TGM seasonal distributions at the two sites were observed, with a descending order of spring, winter, autumn and summer. The different seasonal monsoons were the dominant factor controlling the seasonal variability of the TGM, with variations in the boundary layer and oxidation also possibly partially contributing. Different diurnal patterns of the TGM at two sites were observed. TGM levels during the daytime were higher than those during the nighttime and were predominantly influenced by mountain and valley winds at the DH site, whereas the opposite trend was evident at the GZ site, which was primarily influenced by the boundary-layer height and O3 concentration. During the monitoring period, the correlations between the daily TGM levels and the SO2 and NO2 levels at the DH site were significant (r = 0.36, p mercury for this regional monitoring site. At the GZ site, the correlations between the daily TGM level and the NO, NO2, CO levels were significant (r = 0.501, p mercury sources for this urban monitoring site. The TGM distribution

  15. Macroalgae Laminaria digitata and Saccharina latissima as Potential Biomasses for Biogas and Total Phenolics Production: Focusing on Seasonal and Spatial Variations of the Algae

    DEFF Research Database (Denmark)

    D'Este, Martina; Alvarado-Morales, Merlin; Ciofalo, Anna

    2017-01-01

    the best period of the year and location to cultivate macroalgae for biofuels and biochemical production. Therefore, the biogas potential and the total phenolics profile for L. digitata and S. latissima were determined. The total phenolics were determined as they may represent an interesting bioactive...

  16. Biological variation and reference intervals for circulating osteopontin, osteoprotegerin, total soluble receptor activator of nuclear factor kappa B ligand and high-sensitivity C-reactive protein

    DEFF Research Database (Denmark)

    Sennels, H P; Jacobsen, Søren; Jensen, T

    2007-01-01

    Objective. Monitoring inflammatory diseases and osteoclastogenesis with osteopontin (OPN), osteoprotegerin (OPG), total soluble receptor activator of nuclear factor kappa B ligand (total sRANKL) and high-sensitivity C-reactive protein (hsCRP) has recently attracted increased interest. The purpose...

  17. Biological investigations of Indian phaeophyceae: 17. Seasonal variation of antibacterial activity of total sterols obtained from frozen samples of Sargassum johnstonii Setchell et Gardner

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, P.P.S.

    From lipid fraction of frozen samples of Sargassum johnstonii unsaponifiable part was extracted with diethyl ether to isolate total sterols. The extracted sterols were obtained for a period of nine months and tested against test bacteria...

  18. Seasonal to hour variation scales in abundance and production of total and particle-attached bacteria in the open NW Mediterranean Sea (0–1000 m

    Directory of Open Access Journals (Sweden)

    G. Mével

    2008-11-01

    Full Text Available We present the vertical and temporal dynamics of total vs. particle-attached bacterial abundance and activity over a 5 week period under summer to autumn transition in NW Mediterranean Sea. At a weekly time scale, total bacterial biomass and production in the euphotic layers was significantly correlated with phytoplanktonic biomass. At an hourly time scale, total bacterial biomass responded very rapidly to chlorophyll a fluctuations, suggesting a tight coupling between phytoplankton and bacteria for resource partitioning during the summer-autumn transition. In contrast, no influence of diel changes on bacterial parameters was detected. Episodic events such as coastal water intrusions had a significant positive effect on total bacterial abundance and production, whereas we could not detect any influence of short wind events whatever the magnitude. Finally, we show that particle-attached bacteria can represent a large proportion (up to 49% of the total bacterial activity in the euphotic layer but display rapid and sporadic changes at hourly time scales. In the mesopelagic layers, bacterial abundance and production linearly decreased with depth, except some production peaks at 400–750 m. This study underlines the value of large datasets covering different temporal scales to clarify the biogeochemical role of bacteria in the cycling of organic matter in open seawater.

  19. Seasonal variations of total {sup 234}Th and dissolved {sup 238}U concentration activities in surface water of Bransfield Strait, Antarctica, from March to October 2011

    Energy Technology Data Exchange (ETDEWEB)

    Lapa, Flavia V.; Oliveira, Joselene de; Costa, Alice M.R., E-mail: fvlapa@ipen.br, E-mail: jolivei@ipen.br, E-mail: lice_mrc@hotmail.com [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), Sao Paulo, SP (Brazil). Laboratorio de Radiometria Ambiental; Braga, Elisabete S., E-mail: edsbraga@usp.br [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Inst. Oceanografico. Lab. de Nutrientes, Micronutrientes e Tracos nos Oceanos

    2013-07-01

    In this study the naturally occurring radionuclides {sup 234}Th and {sup 238}U were used to investigate the magnitude of upper ocean particulate organic carbon export in Bransfield Strait, Southern Ocean. This region is the largest oceanic high-nitrate low-chlorophyll (HNLC) area in the world and is known to contribute to regulate of the atmospheric CO{sub 2} via the biological pump. Due to its different geochemical behavior in seawater, the resulting U/Th disequilibria can be easily used to constrain the transport rates of particles and reaction processes between solution and particulate phases. Sampling occurred during the summer (March and November) 2011. Total {sup 234}Th activities in surface seawater samples ranged from 1.3 to 3.7 dpm L{sup -1} (station EB 011) during March/11 campaign, while in October/11 total {sup 234}Th activity concentrations varied from 1.4 to 2.9 dpm L{sup -1}. Highest total {sup 234}Th activities were found late in the austral summer season. Activity concentrations of dissolved {sup 238}U in surface seawater varied from 2.1 to 2.4 dpm L{sup -1}. Taking into account all sampling stations established in March and October/11 the relative variability of total {sup 234}Th distribution was 22%. (author)

  20. Seasonal and biological variation of blood concentrations of total cholesterol, dehydroepiandrosterone sulfate, hemoglobin A(1c), IgA, prolactin, and free testosterone in healthy women

    DEFF Research Database (Denmark)

    Garde, A H; Hansen, Åse Marie; Skovgaard, L T

    2000-01-01

    Concentrations of physiological response variables fluctuate over time. The present study describes within-day and seasonal fluctuations for total cholesterol, dehydroepiandrosterone sulfate (DHEA-S), hemoglobin A(1c) (HbA(1c)), IgA, prolactin, and free testosterone in blood, and estimates within...

  1. 渭北油田高水垂比水平井钻井设计与应用%The Design and Application of Horizontal Well Drilling with High Dep/TVD Ratio in the Weibei Oilfield

    Institute of Scientific and Technical Information of China (English)

    闫吉曾

    2015-01-01

    To solve drilling difficulties in the Chang‐3 Reservoir of the Weibei Oilfield that displayed high friction and difficult well trajectory control caused by shallow burial depth and high ratio of horizontal departure and true vertical depth(Dep/TVD) ,the research on horizontal drilling technology with high ratio of Dep/TVD in shallow reservoir was conducted .Based on an analysis of the primary drilling technology difficulties in the oilfield ,a numerical simulation for friction and torque was made in different hole sizes . Three spudding well sections were adopted ,and φ215.9 mm drill bits were used to drill the last horizontal section .In order to ensure accurate landing and targeting ,a double build hole profile was adopted according to the geological characteristics of the Chang‐3 Reservoir .According to characteristics and drilling require‐ments of the formations drilled in the three sections ,the first section adopted a tapered bottomhole assem‐bly ,the second and the third spudding sections adopted inverted BHA that the heavy weight drill pipe was applied in the hole section with a deviation angle of 45° to 60° ,a potassium ammonium‐based polymer drill‐ing fluid was used and the fluid loss less than 5 mL in the horizontal section .To reduce drilling cost ,the existing drilling rig ZJ30 without a top drive was selected .Field practice shows that ,the conventional drill‐ing equipment and drilling technology mentioned above can be used to solve the drilling difficulties of shal‐low horizontal wells ,so as to achieve the effective the development for the Chang‐3 Reservoir of the Weibei Oilfield .%为解决渭北油田长3储层埋深浅、水平井水垂比高带来的摩阻大、井眼轨迹控制难等问题,开展了浅层高水垂比水平井钻井设计研究。在分析主要钻井技术难点的基础上,对不同尺寸井眼的摩阻和扭矩进行了数值模拟,将待钻井设计为三开井身结

  2. Satellite-observed changes in vegetation sensitivities to surface soil moisture and total water storage variations since the 2011 Texas drought

    Science.gov (United States)

    A, Geruo; Velicogna, Isabella; Kimball, John S.; Du, Jinyang; Kim, Youngwook; Colliander, Andreas; Njoku, Eni

    2017-05-01

    We combine soil moisture (SM) data from AMSR-E and AMSR-2, and changes in terrestrial water storage (TWS) from time-variable gravity data from GRACE to delineate and characterize the evolution of drought and its impact on vegetation growth. GRACE-derived TWS provides spatially continuous observations of changes in overall water supply and regional drought extent, persistence and severity, while satellite-derived SM provides enhanced delineation of shallow-depth soil water supply. Together these data provide complementary metrics quantifying available plant water supply. We use these data to investigate the supply changes from water components at different depths in relation to satellite-based enhanced vegetation index (EVI) and gross primary productivity (GPP) from MODIS and solar-induced fluorescence (SIF) from GOME-2, during and following major drought events observed in the state of Texas, USA and its surrounding semiarid area for the past decade. We find that in normal years the spatial pattern of the vegetation-moisture relationship follows the gradient in mean annual precipitation. However since the 2011 hydrological drought, vegetation growth shows enhanced sensitivity to surface SM variations in the grassland area located in central Texas, implying that the grassland, although susceptible to drought, has the capacity for a speedy recovery. Vegetation dependency on TWS weakens in the shrub-dominated west and strengthens in the grassland and forest area spanning from central to eastern Texas, consistent with changes in water supply pattern. We find that in normal years GRACE TWS shows strong coupling and similar characteristic time scale to surface SM, while in drier years GRACE TWS manifests stronger persistence, implying longer recovery time and prolonged water supply constraint on vegetation growth. The synergistic combination of GRACE TWS and surface SM, along with remote-sensing vegetation observations provides new insights into drought impact on

  3. Anthropogenic versus geogenic contribution to total suspended atmospheric particulate matter and its variations during a two-year sampling period in Beijing, China.

    Science.gov (United States)

    Schleicher, Nina; Norra, Stefan; Chai, Fahe; Chen, Yizhen; Wang, Shulan; Stüben, Doris

    2010-02-01

    Weekly samples of total suspended particles in air (TSP) were taken in south-east Beijing for a two-year period continuously from August 2005 to August 2007. Mass concentrations varied between 76 and 1028 microg m(-3) with an average concentration of 370 microg m(-3) for the whole period. The chemical composition and the mass concentration of aerosols in combination with meteorological data are reflecting specific influences of distinct aerosol sources on the pollution of Beijing's atmosphere. Lead (Pb), titanium (Ti), zinc (Zn) and copper (Cu) concentrations were chosen as indicator elements for different sources. Their amounts considerably varied over the course of the year. Element ratios, such as Pb/Ti, supported the distinction between periods of predominant geogenic or anthropogenic caused pollution. However, the interactions between aerosols from different sources are numerous and aerosol pollution still is a big and complex challenge for the sustainable development of Beijing.

  4. Association between variations in the TLR4 gene and incident type 2 diabetes is modified by the ratio of total cholesterol to HDL-cholesterol

    Directory of Open Access Journals (Sweden)

    Meisinger Christine

    2008-02-01

    Full Text Available Abstract Background Toll-like receptor 4 (TLR4, the signaling receptor for lipopolysaccharides, is an important member of the innate immunity system. Since several studies have suggested that type 2 diabetes might be associated with changes in the innate immune response, we sought to investigate the association between genetic variants in the TLR4 gene and incident type 2 diabetes. Methods A case-cohort study was conducted in initially healthy, middle-aged subjects from the MONICA/KORA Augsburg studies including 498 individuals with incident type 2 diabetes and 1,569 non-cases. Seven SNPs were systematically selected in the TLR4 gene and haplotypes were reconstructed. Results The effect of TLR4 SNPs on incident type 2 diabetes was modified by the ratio of total cholesterol to high-density lipoprotein cholesterol (TC/HDL-C. In men, four out of seven TLR4 variants showed significant interaction with TC/HDL-C after correction for multiple testing (p -3. However, none of the investigated variants or haplotypes was associated with type 2 diabetes in main effect models without assessment of effect modifications. Conclusion We conclude that minor alleles of several TLR4 variants, although not directly associated with type 2 diabetes might increase the risk for type 2 diabetes in subjects with high TC/HDL-C. Additionally, our results confirm previous studies reporting sex-related dissimilarities in the development of type 2 diabetes.

  5. CO, CH4 and H2O total contents: long-term Russian and Chinese spectroscopic datasets, seasonal, weekly and diurnal variations and temporal tendencies

    Science.gov (United States)

    Rakitin, Vadim; Grechko, Eugeny; Wang, Gengchen; Dzhola, Anatoly; Fokeeva, Ekaterina; Safronov, Alexandr

    2016-04-01

    Analysis of the CO total column (TC) long-term measurements in Moscow and Beijing for period from 1992 to 2015 years is presented. Similar data of CO, CH4 and H2O columns for Zvenigorod Scientific Station (ZSS) in 1970-2015 years are analyzed. The rate of decrease of anthropogenic portion in CO TC over Moscow was equal to 1.4 % per year for 1992-2015 years in spite of multiple increase of the motor vehicles number. CO TC decrease was observed in Beijing in 1992 - 2015 years with the rate 1.1% per year. Typical levels of atmospheric CO and aerosols pollution in Beijing is 2-5 times stronger in comparison with Moscow ones. Reasonably typical events for Beijing with extreme values of CO TC and aerosols concentrations were observed in Moscow during wild fires of 2002 and 2010 years only. Trajectory cluster analysis using has allowed an investigation of CO and aerosols emissions sources location. Relatively stronger atmospheric pollution of Beijing partially due to the atmospheric transportation from distant industry regions of China located at 100-500 km from Beijing toward south, south-east and east directions. Satellite observations (AIRS v6) have demonstrated the CO TC slow decrease in Moscow rural region and the significant decrease of CO TC over Beijing (2002-2014). Rate of CH4 TC increase in Moscow region is 0.5% per year for 1972-2015. This work was supported by the Russian Scientific Foundation under grant №14-47-00049 and partially by the Russian Foundation for Basic Research (grant № 16-05-00287).

  6. Numerical Implementation of Adaptive Fidelity Term Denoising Algorithm Based on Total Variation%基于全变分自适应保真项去噪算法的数值实现

    Institute of Scientific and Technical Information of China (English)

    王宏志; 刘婉军; 韩啸

    2014-01-01

    On the basis of the classical algorithm of the image denoising based on total variation,a numerical algorithm of total variation based on adaptive fidelity term was proposed. Different intensities of denoising were used to avoid the shortages of the traditional method and then numerical method was chosen so as to realize our algorithm.On the premise of the classical total variation,our method made up for the shortcomings of the original ladder and excessive smoothing effect,especially for the image denoising of fine texture and detail images,it made the remain of most of their image characteristics.Our treatment can be applied to a series of image processing based on partial differential equations simply.%基于全变差图像去噪经典算法,提出一种自适应保真项的数值实现算法。该算法利用图像纹理区和光滑区中噪声的不同特点,采用不同去噪强度避免传统方法的不足,并以数值方法实现。在保持经典算法去噪效果的前提下,解决了原有阶梯效应和过度平滑的问题,尤其对精致的纹理和细节图像,使其在去噪的同时,不丢失图像特点。该方法处理相对简单,可应用于以偏微分方程为基础的图像处理。

  7. Total protein

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/003483.htm Total protein To use the sharing features on this page, please enable JavaScript. The total protein test measures the total amount of two classes ...

  8. Geometric Total Variation for Texture Deformation

    DEFF Research Database (Denmark)

    Bespalov, Dmitriy; Dahl, Anders Lindbjerg; Shokoufandeh, Ali

    2010-01-01

    of features in texture images leads to significant improvements in localization of these features, when textures undergo geometrical transformations. Accurate localization of features in the presense of unkown deformations is a crucial property for texture characterization methods, and we intend to expoit...

  9. Total algorithms

    NARCIS (Netherlands)

    Tel, G.

    1993-01-01

    We define the notion of total algorithms for networks of processes. A total algorithm enforces that a "decision" is taken by a subset of the processes, and that participation of all processes is required to reach this decision. Total algorithms are an important building block in the design of distri

  10. Color filter array interpolation based on contourlet local Gaussian model and total variation%基于轮廓波局部高斯模型与全变差的彩色滤波阵列插值

    Institute of Scientific and Technical Information of China (English)

    丁丽媛; 练秋生

    2011-01-01

    彩色图像的彩色滤波阵列(CFA)插值是从单传感器数字相机通过CFA获得的采样图像中重构完整RGB图像的过程.针对Bayer格式图像提出了一种基于轮廓波局部高斯模型与全变差的彩色图像CFA插值算法.为进一步提高图像边缘插值质量,将图像梯度的稀疏性结合到图像插值过程中,并且图像梯度的稀疏性用彩色全变差(CTV)来衡量.实验结果表明,该算法比现有的图像插值算法在峰值信噪比与主观视觉效果两方面均有显著提高.%Single-chip digital cameras use Color Filter Array (CFA) to sample different color information; the color image CFA interpolation algorithm interpolates these data to produce an RGB image. A color image CFA interpolation algorithm was proposed based on contourlet local Gaussian model and Total Variation (TV). In order to improve the edge interpolation quality, the sparsity of image gradient was integrated in interpolation process, and the Color Total Variation (CTV) was introduced to measure the sparsity of the image gradient. The experimental results show that the proposed algorithm outperforms the classical algorithms in terms of both Peak Signal-to-Noise Ratio (PSNR) and visual quality.

  11. 基于投影数据非单调性全变分恢复的低剂量CT重建%Nonmonotone Total Variation Minimization Based Projection Restoration for Low-Dose CT Reconstruction

    Institute of Scientific and Technical Information of China (English)

    钱姗姗; 黄静; 马建华; 张华; 刘楠; 张喜乐; 冯前进; 陈武凡

    2011-01-01

    为获取低剂量CT图像的优质重建,本文提出一种基于投影数据非单调性全变分恢复的低剂量CT重建方法.新方法首先通过非线性Anscombe变换将满足Poisson分布的投影数据转化为近似Gaussian分布,其后对变换后的Gaussian型数据进行非单调性全变分最小化算法(Nonmonotone Total Variation Minimization,NTVM)滤波,最后对Anscombe逆变换数据实现传统的滤波反投影(Filtered Back Projection,FBP) CT重建.仿真和临床低剂量CT重建实验表明,本文方法在噪声清除、伪影抑制和缩短重建时间等方面均有上佳表现.%In order to improve the reconstruction quality of low-dose CT image,a new approach is proposed based on low-dose CT projection restoration in this paper. First, projection data is transformed from Poisson distribution to Gaussian distribution using nonlinear Anscombe transform. Then, the Anscombe transformed data is filtered by an efficient nonmonotone total variation minimization denoising algorithm. Last, the reconstruction is achieved by inverse Anscombe transform and filtered back projection (FBP) method. Simulated and clinical low-dose CT data experimental results demonstrate that a high-quality CT image can be reconstructed.

  12. Novel Single Hazy Image Restoration Method Based on Nonlocal Total Variation Regularization Optimization%基于非局部全变分正则化优化的单幅雾天图像恢复新方法

    Institute of Scientific and Technical Information of China (English)

    何人杰; 樊养余; WANG Zhiyong; FENG David

    2016-01-01

    Based on the property that the scene radiance is of high contrast and the atmospheric veil is locally smooth, a novel single hazy image restoration method based on nonlocal total variation regularization optimization is proposed in this paper. In order to obtain the atmospheric veil of a hazy image, a constrained nonlocal total variation regularization is firstly applied. Then, the accurate atmospheric veil is estimated using a nonlocal Rudin- Osher-Fatemi model, which is solved by a modified split Bregman method. Experimental results demonstrate that the proposed approach is capable of recovering the scene radiance from a single hazy image effectively, especially for the regions with multi-texture.%该文针对无雾图像具有高灰度对比度且大气遮罩局部平滑的特性,提出一种基于非局部全变分正则化优化的单幅雾天图像恢复新方法。先构建一种基于非局部全变分正则化的有约束优化算法对大气遮罩进行估计,然后通过优化Bregman分离迭代法求解非局部Rudin-Osher-Fatemi模型获得准确的大气遮罩,进而从雾天场景图像恢复出场景图像。实验结果表明,所提新方法可以有效地对雾天降质图像进行复原,对多纹理复杂区域的恢复效果也较好。

  13. Study on the Ionospheric TEC Variations During the Total Solar Eclipse of July 22,2009%2009年7月22日日全食期间电离层总电子含量变化研究

    Institute of Scientific and Technical Information of China (English)

    莫晓华; 张东和; 覃健生; 叶锦凤; 萧佐

    2012-01-01

    Variations of the ionospheric Total Electron Content(TEC) during the total solar eclipse of July 22,2009 was investigated using GPS observed data obtained at five GPS stations(one is in total solar eclipse region,the others are in partial solar eclipse region) in China region.Results indicate that during the total solar eclipse,TEC experiences a decline and recovery process;the delay of a minimum level of TEC with respect to the maximum phase of the eclipse is about 1~10min;the Ionosphere Pierce Point(IPP) of minimum TEC is closer to total solar eclipse region,the decrease of TEC is larger,and during the total solar eclipse,the mean decay TEC compared to the TEC on reference date above WUHN station(114.35°E,30.53°N) is the maximum,reaching 4.58 TECU.%利用中国区域内五个GPS台站(一个台站处于日全食区域、四个台站处于日偏食区域)观测数据,研究2009年7月22日日全食期间电离层总电子含量(TEC)的变化,结果表明,日全食期间,电离层TEC值经历了下降和恢复的过程,最小TEC相对于最大食偏的时间延迟约为1~10 min;台站测得最小TEC的星下点(IPP)越靠近日全食带TEC下降量越大,在日食期间武汉站(114.35°E,30.53°N)TEC相对于各参考日期的TEC,其平均下降量最大,达到4.58TECU.

  14. [Analysis of variance of bacterial counts in milk. 1. Characterization of total variance and the components of variance random sampling error, methodologic error and variation between parallel errors during storage].

    Science.gov (United States)

    Böhmer, L; Hildebrandt, G

    1998-01-01

    In contrast to the prevailing automatized chemical analytical methods, classical microbiological techniques are linked with considerable material- and human-dependent sources of errors. These effects must be objectively considered for assessing the reliability and representativeness of a test result. As an example for error analysis, the deviation of bacterial counts and the influence of the time of testing, bacterial species involved (total bacterial count, coliform count) and the detection method used (pour-/spread-plate) were determined in a repeated testing of parallel samples of pasteurized (stored for 8 days at 10 degrees C) and raw (stored for 3 days at 6 degrees C) milk. Separate characterization of deviation components, namely, unavoidable random sampling error as well as methodical error and variation between parallel samples, was made possible by means of a test design where variance analysis was applied. Based on the results of the study, the following conclusions can be drawn: 1. Immediately after filling, the total count deviation in milk mainly followed the POISSON-distribution model and allowed a reliable hygiene evaluation of lots even with few samples. Subsequently, regardless of the examination procedure used, the setting up of parallel dilution series can be disregarded. 2. With increasing storage period, bacterial multiplication especially of psychrotrophs leads to unpredictable changes in the bacterial profile and density. With the increase in errors between samples, it is common to find packages which have acceptable microbiological quality but are already spoiled by the time of the expiry date labeled. As a consequence, a uniform acceptance or rejection of the batch is seldom possible. 3. Because the contamination level of coliforms in certified raw milk mostly lies near the detection limit, coliform counts with high relative deviation are expected to be found in milk directly after filling. Since no bacterial multiplication takes place

  15. VARIACIÓN DEL CONTENIDO DE AZÚCARES TOTALES Y AZÚCARES REDUCTORES EN EL MUSGO Pleurozium schreberi (HYLOCOMIACEAE BAJO CONDICIONES DE DÉFICIT HÍDRICO Variation in Total Sugars and Reductive Sugars in the Moss Pleurozium schreberi (HYLOCOMIACEAE Under Water Deficit Conditions

    Directory of Open Access Journals (Sweden)

    LUIS CARLOS MONTENEGRO RUIZ

    2012-12-01

    Full Text Available Los briófitos por su simplicidad estructural se ven expuestos a estrés hídrico con facilidad, por lo que presentan mecanismos fisiológicos y bioquímicos que les permita sobrevivir. En el presente trabajo se evaluó la variación del contenido de azúcares totales solubles y azúcares reductores en relación con el contenido hídrico relativo, en Pleurozium schreberi cuando se enfrenta a contenidos hídricos bajos en el Páramo de Chingaza (Colombia y bajo condiciones simuladas de déficit hídrico en laboratorio. Se encontró que los azúcares totales aumentan cuando la planta se deshidrata y vuelve a su contenido normal cuando el musgo se rehidra, esto puede ser interpretado como un posible mecanismo de ajuste osmótico de la célula y osmoprotección del contenido celular y de la estructura celular. Los azúcares reductores no presentaron variación significativa, mostrando que los monosacáridos no tienen una función protectora durante la deshidratación.The structural simplicity of the bryophytes exposed them easily to water stress, forcing them to have physiological and biochemical mechanisms that enable them to survive. This study evaluated the variation of total soluble sugars and reducing sugars in relation to relative water content, in Pleurozium schreberi when faced with low water content in the Páramo de Chingaza (Colombia and under simulated conditions of water deficit in the laboratory. We found that total sugars increase when the plant is dehydrated and returned to their normal content when re-hydrated moss, this could be interpreted as a possible mechanism of osmotic adjustment and osmoprotection of the cell content and cellular structure. Reducing sugars showed no significant variation, showing that monosaccharides do not have a protective role during dehydration.

  16. Evaluation method of optical properties for photonic crystal fibers based on total variation and wavelet model%结合全变差和小波变换的PCF光特性评估方法

    Institute of Scientific and Technical Information of China (English)

    申艳; 解颐; 娄淑琴

    2016-01-01

    Based on the combination model of total variation and wavelet transform, an improved method was proposed to rapidly evaluate the optical properties of actual Photonic Crystal Fibers ( PCFs ) . Firstly , the total variation model in the wavelet domain was set up in this paper. Secondly, the split Bregman algorithm was used iteratively to denoise the cross-section images of PCFs, and thus the edge structures of air holes of PCFs image was kept. Thirdly, the optical properties of practical PCFs were evaluated rapidly by the adoption of the finite element method. By analyzing microscope images of cross sections of commercial and homemade PCFs, it is proved that the proposed method can achieve higher evaluation accuracy of optical properties of PCFs and the Gibbs and staircase effect can be eliminated efficiently in the extraction process of the edges of air holes in PCFs image.%为了更准确、快速评估实际光子晶体光纤的光特性,提出了一种基于全变差和小波变换的实际光子晶体光纤光特性评估方法。建立了在小波变换域上的全变差模型,利用Bregman算法进行迭代运算,有效地滤除光子晶体光纤截面图像的噪声,并保持截面图像空气孔的边缘结构,进而结合有限元方法,实现实际光子晶体光纤的光特性的准确快速评估。通过对商用及自制光子晶体光纤的特性评估,验证了所提出方法的有效性。文中所提出的方法结合了全变差和小波变换的优点,可以有效去除吉布斯现象和阶梯效应的影响,提高了光子晶体光纤光特性评估的精度。

  17. Solar irradiance, total and spectral; Irradiancia solar, total e espectral

    Energy Technology Data Exchange (ETDEWEB)

    Fraidenraich, Naum [Pernambuco Univ., Recife, PE (Brazil). Centro de Energia Nuclear; Lyra, Francisco [Companhia Hidroeletrica do Sao Francisco (CHESF), Recife, PE (Brazil)

    1995-12-31

    In this chapter some important characteristics concerning solar irradiance are presented, such as: solar constant; spectral irradiance for a zeroed mass of air; solar constant variation according to Earth-Sun distance; solar energy variation on Earth`s surface; atmospheric attenuation of solar energy; and total radiation and spectral irradiation on Earth`s surface. 3 refs., 5 figs., 6 tabs.

  18. Seasonal variations and evidence for the effectiveness of pollution controls on water-soluble inorganic species in total suspended particulates and fine particulate matter from Xi'an, China.

    Science.gov (United States)

    Shen, Zhenxing; Arimoto, Richard; Cao, Junji; Zhang, Renjian; Li, Xuxiang; Du, Na; Okuda, Tomoaki; Nakao, Shunsuke; Tanaka, Shigeru

    2008-12-01

    Total suspended particulate (TSP) and particulate matter less than 2.5 microm in aerodynamic diameter (PM2.5) samples were collected over Xi'an for a 1-yr period to characterize the seasonal variations of water-soluble inorganic ions and to evaluate the effectiveness of the pollution policies and controls during the past 10 yr. Mass concentrations of five cations (sodium [Na+], potassium [K+], ammonium [NH4+], calcium [Ca2+], and magnesium [Mg2+]) and four anions (fluoride [F-], chloride [Cl-], nitrate [NO3-], and sulfate [SO4(2-)]) were determined by ion chromatography. The yearly arithmetic-mean mass concentrations of the total measured water-soluble ions in TSP and PM2.5 were 83.9 +/- 58.4 and 45 +/- 34.3 microg x m(-3). The most abundant ions in TSP were SO4(2-), NO3-, Ca2+, and NH4+; whereas in PM2.5 the dominant ions were SO4(2-), NH4 +, and NO3-. Most of the ions were more concentrated in the PM2.5 than in TSP, but two exceptions were Ca2+ and Mg2+. Comparisons of the molar ratios of Mg2+/Ca2+ in TSP indicated that fugitive dust was the main source for these two ions, and the influence of soil dust from outside of the city was most evident during dust storms. The mass concentrations of SO4(2-), NO3-, , NH4+, and K+ in TSP were highest in winter and lowest in spring, but Ca2+ was much higher in spring than other seasons because of suspended mineral dust. In PM2.5, NO3- and K+ also showed winter maxima, but SO4(2-) and NH4+ were highest in summer. Calculations of ion equivalents showed that TSP samples were more alkaline than PM2.5, the latter being weakly acidic in winter and autumn. High sulfur and nitrogen oxidation ratios occurred in summer and autumn, and there was evidence for the formation of ammonium bisulfate in TSP, ammonium sulfate in PM2.5, and ammonium nitrate in both fractions. Comparisons with the results of prior studies indicate that pollution controls in Xi'an have reduced the levels of air pollution over the past 10 yr. The SO4

  19. Total Factor Productivity and its Spatial Variation in Jiangsu from 1993 to 2009%江苏省生产效率与全要素生产率分解的空间格局演变分析

    Institute of Scientific and Technical Information of China (English)

    牛品一; 陆玉麒; 彭倩

    2012-01-01

    Total factor productivity is a basic index reflecting the quality of economic growth and the rate of technical progress in a country or a region. Empirical study is conducted to test Jiangsu's counties datasets (1990-2006), using a translog production frontier specification with heterogeneous technical efficiency explained by exogenous variables. This paper measures technical efficiency between 65 counties (cities) of Jiangsu and decomposes the growth rate of TFP (Total Factor Productivity) to technical efficiency, technology progress and scale economic. This paper analyzes the relationship between TFP and economic growth, then classifies the economic growth patterns of 65 counties (cities) into four categories according to the speed of TFP and economic growth, and finally discusses the spatial divergence of TFPs and economic growth rates among 65 counties (cities).The findings of this study show:(1) Southem Jiangsu technical efficiency was the highest, technical efficiency of Northern Jiangsu was the lowest. Southern smallest decrease and northern had the largest decline. Within the Southern areas technical efficiency was more balanced, while within the middle and northern areas there was a differentiation. (2)Urbanization rate, the proportion of secondary industry in GDP, the ratio of exports and GDP are important factors for efficiency improvement, but government intervention are harmful to efficiency. (3)Regional growth rate of total factor productivity was increased; TFP growth of the southem Jiangsu was steady, while the variation of TFP in the middle and northern Jiangsu was big. TFP growth was mainly due to technology progress. Technical efficiency of southem Jiangsu to TFP growth with minimal impact, technical efficiency change of northern Jiangsu made great impact on TFP growth rate which contribution rate was -188.66%.(4)1993-2002, total factor productivity growth was not related with the level of economic development, the region with low level of

  20. Total Thyroidectomy

    Directory of Open Access Journals (Sweden)

    Lopez Moris E

    2016-06-01

    Full Text Available Total thyroidectomy is a surgery that removes all the thyroid tissue from the patient. The suspect of cancer in a thyroid nodule is the most frequent indication and it is presume when previous fine needle puncture is positive or a goiter has significant volume increase or symptomes. Less frequent indications are hyperthyroidism when it is refractory to treatment with Iodine 131 or it is contraindicated, and in cases of symptomatic thyroiditis. The thyroid gland has an important anatomic relation whith the inferior laryngeal nerve and the parathyroid glands, for this reason it is imperative to perform extremely meticulous dissection to recognize each one of these elements and ensure their preservation. It is also essential to maintain strict hemostasis, in order to avoid any postoperative bleeding that could lead to a suffocating neck hematoma, feared complication that represents a surgical emergency and endangers the patient’s life.It is essential to run a formal technique, without skipping steps, and maintain prudence and patience that should rule any surgical act.

  1. 2009年7月22日日全食期间电离层参量的变化%Variations of Ionospheric Parameters During the Total Solar Eclipse on 22 July 2009

    Institute of Scientific and Technical Information of China (English)

    丁宗华; 孙树计; 陈春; 李娜; 许正文

    2011-01-01

    The variations of ionospheric parameters including fmin, f0E2 and TEC during the total solar eclipse of 22 July 2009 are investigated. The results show that the fmin drops quickly after the eclipse commencement and then gradually restores to the normal value. The f0F2 and TEC decrease greatly during the eclipse maximum. These phenomena are probably caused by the fact that the solar electromagnetic radiation decrease sharply during the solar eclipse. The f0F2 and TEC show some positive disturbance which is more notable near to the equatorial abnormal crest region on about 5~6 hours and some negative disturbance on about 9~10 hours after this eclipse. Combining the analysis of the solar and geomagnetic activity, we think that it seems difficult to further investigate the eclipse ionospheric effect since the space weather events including magnetic storm and electric field penetration are accompanying this event.%利用多个电离层垂测站的数据和IGS-TEC数据资料,结合日地空间环境指数,分析了2009年7月22日日全食期间中国地区电离层参量(反射回波最低频率fmin及f0f2和TEC)的变化特征.结果表明,日食发生后fmin迅速降低,日食结束后fmin迅速恢复到正常水平;在食甚时刻附近,f0F2和TEC出现明显的降低,显示了明显的光食效应.日食结束后5~6 h,f0F2和TEC出现不同程度的正扰动,在驼峰区更明显;日食结束后9~10 h,f0F2和TEC出现较显著的负扰动.由于此次日食发生时伴随着中等强度的磁暴和低纬电场穿透等空间天气事件,给此次日食电离层效应的深入分析带来很大困难.

  2. 先验图像约束的全变差正则化 CT 图像重建算法%Prior image constrained total variation regularization CT image reconstruction algorithm

    Institute of Scientific and Technical Information of China (English)

    袁媛; 齐宏亮; 耿庆山; 周凌宏

    2015-01-01

    为解决基于先验图像的压缩感知 CT 图像重建算法中,当先验图像与待重建图像结构位置存在偏差时,无法得到良好结果的问题,提出一种先验图像约束的全变差正则化 CT 图像重建算法。选择与待重建图像类似的先验图像,计算先验图像中几种均匀介质的像素平均值作为先验信息;对投影数据进行 ART 算法重建,并加入非负约束,得到中间图像;将先验信息融入到基于全变差的最小化目标函数中,对中间图像进行优化;以上两步骤循环进行,直到满足收敛准则。采用 Shepp-Logan 体模进行仿真重建,仿真结果表明,该算法和 ART-TV、PICCS 算法相比,信噪比更高,误差更小,图像质量更优。%The CT image reconstruction algorithm based on prior image constrained compressed sensing (PICCS)fails to obtain good results when the motion between the prior image and to-be-reconstructed image is apparent.A prior image constrained total variation (TV)regularization reconstruction algorithm was proposed to solve this problem.Firstly,an image with good quality was selected as the prior image which was similar to the to-be-reconstructed image and the average pixel value of the prior image’s each homogeneous region was calculated as the priori information.Secondly,the projection data were reconstructed using the ART algorithm to obtain the intermediate image.The positivity constraint was added to it.Thirdly,the intermediate image was opti-mized using TV regularization combining with priori information.The above two steps cycled until the convergence criterion was met. Results of Simulation experiments with the Shepp-Logan phantom demonstrate that the proposed algorithm is better than ART-TV and PICCS algorithm,it significantly improves signal to noise ratio and suppresses the noise,thus the image quality is improved.

  3. Non-local total variation speckle filtering based on region segmentation%基于区域分割的非局部全变差SAR相干斑滤波

    Institute of Scientific and Technical Information of China (English)

    范惠玲; 曲长文; 李健伟

    2016-01-01

    Due to the limit of imaging system, synthetic aperture radar images are often corrupted with non-Gaussian multiplicative speckle noise. For the purpose of noise suppression, an algorithm called NLM-TV is proposed, which integrates non-local means filter and total variation regularization. It involves three steps. First, convert the multiplicative noise into signal-dependent additive noise, dividing the image into three categories based on noise level, the edge, the strong scattering region and the weak scattering region. Non-local means filter was then applied. To maintain the edge structure effectively, the smooth parameter must be small. In the strong scattering region, TV regularization was used because of insufficient reduction of speckles. In this paper, several simulations were conducted in RADARSAT-2 and TerraSAR-X images, the results showed that compared to a variety of filtering algorithms, NLM-TV algorithm could significantly increase the equivalent number of looks both in the weak scattering area and strong scattering regions. At the same time, edge keeping index could be increased by more than 10%.%受成像体制影响,合成孔径雷达(Synthetic aperture radar,SAR)图像带有非高斯的乘性相干斑噪声。为有效抑制乘性相干斑噪声,提出一种融合非局部均值滤波(Non-local means filter, NLMF)与全变差(Total variation,TV)正则化的非局部均值-全变差(NLM-TV)降噪算法。首先将相干斑噪声转换为依赖于散射强度的加性噪声,将SAR图像分为边缘、强散射区、弱散射区。然后利用NLMF进行降斑,为有效的保持边缘结构, NLMF的平滑参数选取较小。在强散射区,为解决平滑参数较小所带来的降斑不充分问题,进一步使用TV正则化进行平滑处理,获得最终的降噪结果。使用RADARSAT-2,TerraSAR-X两景实测SAR图像仿真实验,结果表明:相比多种滤波算法, NLM-TV算法在弱散射区,强散

  4. Regularized Super-resolution Reconstruction Based on Bilateral Total Variation Model with Adaptive Constraints%自适应约束下的双边全变差正则化超分辨率重建

    Institute of Scientific and Technical Information of China (English)

    周芹; 马志强; 单勇; 党建国

    2015-01-01

    在经典的双边全变差( BTV)超分辨率重建中,加权系数和正则化参数的恒定性导致重建结果边缘保持能力受限。为此,提出了一种自适应约束的BTV正则化先验模型。算法首先定义了图像的局部邻域残差均值以区分当前像素属于平坦区域还是边缘区域;然后针对加权系数的不变性导致边缘削弱的问题,利用边缘方向和垂直边缘方向扩散性的不同,设计自适应权重矩阵;最后根据代价函数的极值问题推导出迭代公式,从而进行图像的超分辨率重建,重建过程中采用自适应的方法确定正则化参数,以便求得代价函数的全局最优解,提高了算法的鲁棒性。实验结果表明:与双三次线性插值法和经典BTV算法相比,该算法取得了更好的视觉效果和更高的峰值信噪比,更多地保留了图像的边缘细节信息。%In the classical super-resolution reconstruction algorithm based on the Bilateral Total Variation ( BTV) model,the ability of edge preserving is restricted due to the constancy of the weighted coefficient and the regularization parameter. To solve the problem, an adaptive regularization BTV model is proposed. Firstly,the algorithm defines the local neighborhood residual mean of the image to distinguish wheather the pixel belongs to flat area or edge area. Then, the adaptive weighting matrix is designed in case that the con-stant weighted coefficient leads to the weaken ability of edge preserving,which takes advantage of the dif-ferent diffusivity between the direction of the edge and the vertical of edge direction;Finally,iterative for-mula is deduced about the extremum problem of the cost function,so that the super-resolution reconstruc-tion can be achieved. In the process the adaptive regularization parameter is adopted in order to get the global optimal value of the cost function. The algorithm improves its robustness. The experimental results show that the

  5. Effect of a common reference plasma on the inter-laboratory variation of the measurement of total and free protein S: a collaborative study of the Dutch Working Group on Haemostasis Laboratory Diagnosis.

    NARCIS (Netherlands)

    Meijer, P.; Verbruggen, H.W.; Weerd, B. de; Dool, E.J. den; Oerle, R. van

    2002-01-01

    The comparability of test results for protein S between laboratories is hampered by a high inter-laboratory variability. The effect of the use and type of common reference plasma on the inter-laboratory variability of the total and free protein S measurement was evaluated. The results of 10 plasma

  6. Special boundedness properties in numerical initial value problems

    NARCIS (Netherlands)

    Hundsdorfer, W.; Mozartova, A.; Spijker, M.N.

    2010-01-01

    For Runge-Kutta methods, linear multistep methods and other classes of general linear methods much attention has been paid in the literature to important nonlinear stability properties known as total-variation-diminishing (TVD), strong stability preserving (SSP) and monotonicity. Stepsize conditions

  7. Proteínas totais do liquido cefalorraqueano obtido por punção da cisterna magna: valores normais. Variações ligadas ao sexo Total protein content of normal cisternal cerebrospinal fluid: Variations related to sex

    Directory of Open Access Journals (Sweden)

    L. M. Singer Vermes

    1976-12-01

    Full Text Available Aplicando o método de Lowry, determinamos as proteínas totais do LCR considerado normal de 98 pessoas: 58 do sexo masculino e 40 do feminino. Todas as amostras de LCR foram obtidas por punção da cisterna magna (LCR-SO. Mediante tratamento estatístico dos valores obtidos, estabelecemos as taxas normais de proteinorraquia cisternal para a população mista: limite superior de 40,36 mg/100 ml, valor médio de 26,78 mg/100 e limite inferior de 13,20 mg/100 ml. Estes valores são superiores àqueles referidos na literatura. Foi verificado que a proteinorraquia total é, em média, significantemente maior nos indivíduos do sexo masculino, que nos de feminino. Consequentemente estabelecemos em separado os níveis normais de proteínas totais do LCR-SO para pessoas do sexo masculino e feminino. As taxas médias de proteínas totais do LCR-SO de pessoas do sexo masculino e feminino são de 28,76 e 23,91 mg/100 ml, respectivamente; os limites normais vão de 16,96 a 47,13 mg/100 ml para o sexo masculino e de 14,76 a 42,76 mg/100 ml para o sexo feminino.The total protein content of CSF collected from the cisterna magna (cisternal fluid of 98 patients (58 males and 40 females with no neurological diseases was determined by the colorimetric method devised by Lowry and co-workers. This method has been previously chosen based mainly on it's sensitivity, accuracy and low fluid consumption. The CSF samples were normal with regard to pressure, color, citology and it's content in glucose, chloride and urea. Complement fixation tests for syphilis and cisticercosis, as well as the globulin tests (Pandy, Nonne — Appelt and Takata-Ara were negative. The average value and the normal range of cisternal fluid total protein was calculated for the mixed population (males and females. The mean protein value was 26.78 mg/100 ml, the lower and upper limits were respectively 13.20 and 40.36 mg/100 ml. These data are higher than those stated in some publications, and

  8. Experiencing variation

    DEFF Research Database (Denmark)

    Kobayashi, Sofie; Berge, Maria; Grout, Brian William Wilson

    2017-01-01

    This study contributes towards a better understanding of learning dynamics in doctoral supervision by analysing how learning opportunities are created in the interaction between supervisors and PhD students, using the notion of experiencing variation as a key to learning. Empirically, we have based...... were discussed, created more complex patterns of variation. Both PhD students and supervisors can learn from this. Understanding of this mechanism that creates learning opportunities can help supervisors develop their competences in supervisory pedagogy....

  9. 海地地震前电离层电子含量数据异常分析%The Variation of Ionospheric Total Electron Content Before Haiti Earthquake

    Institute of Scientific and Technical Information of China (English)

    齐曙光; 杨杰; 郭广猛; 关建平

    2012-01-01

    A devastating MS7.3 earthquake hit the capital of Haiti on January 12, 2010. Here TEC (Total electron content) data provided by NOAA is used to analyze the ionosphere change before Haiti earthquake. First time se- ries TEC data from December 12, 2009 to January 12, 2010 is plotted, and the result shows the TEC value begin to increase 3 days before the quake, and it gets to the maximum value just 1 day before the quake; Second the spatial distribution of TEC map is plotted, and the result shows that the TEC anomaly just exists near the epicenter in the whole north and central America continent; Finally TEC data within 5 degrees around the epicenter is calculated, and it shows the TEC gets to the maximum value 1 days before the quake, and drops after the quake. So by analyzing from the temporal and spatial features, we consider that the TEC anomaly is related to the Haiti earthquake.%利用美国国家海洋和大气管理局(NOAA)提供的电离层总电子含量(TEC)数据,研究了2010年1月12日海地首都太子港发生MS7.3级地震,采用从点到面、从时间到空间的方法分析了震前1个月的TEC变化,发现在海地震前3天TEC出现异常扰动.首先,利用时间序列曲线分析发现2010年1月10至12日之间的TEC异常增大,最大值超过月均值的3倍标准差.其次,利用空间分布图发现10至12日TEC异常区主要分布在震中附近.最后,利用"面-时间段"数据分析发现震中5个经纬度内范围内TEC在震前3天出现异常增大,震前1天达到最大值,震后TEC数值回落.结果分析说明,该异常和海地地震有关.

  10. Yearly variation and annual cycle of total column ozone over New Delhi (29°N, 77°E), India and Halley Bay (76°S, 27°W), British Antarctic Survey Station and its effect on night airglow intensity of OH(8, 3) for the period 1979–2005

    Indian Academy of Sciences (India)

    P K Jana; D K Saha; D Sarkar

    2012-12-01

    A critical analysis made on the long-term monthly, seasonal, yearly variation and annual cycle of total column ozone (TCO) concentration at New Delhi (29°N,77°E), India and Halley Bay (76°S, 27°W), a British Antarctic Service Station reveals more decline in yearly mean ozone concentration at Halley Bay than at New Delhi from 1979 to 2005. The nature of variations of monthly mean TCO during the months of August and September was the most identical with that of yearly mean ozone values at New Delhi and Halley Bay, respectively, for the same period. Annual cycles of TCO over these stations are completely different for the above period. The effect of O3 depletion on night airglow emission of OH(8, 3) line at New Delhi and Halley Bay has been studied. Calculations based on chemical kinetics show that the airglow intensity of OH(8, 3) has also been affected due to the depletion of O3 concentration. The yearly variations and annual cycle of intensities of OH(8, 3) line for the above two stations are depicted and compared. It has been shown that the rate of decrease of intensity of OH(8, 3) line was comparatively more at Halley Bay due to dramatic decrease of Antarctic O3 concentration.

  11. Variational principles

    CERN Document Server

    Moiseiwitsch, B L

    2004-01-01

    This graduate-level text's primary objective is to demonstrate the expression of the equations of the various branches of mathematical physics in the succinct and elegant form of variational principles (and thereby illuminate their interrelationship). Its related intentions are to show how variational principles may be employed to determine the discrete eigenvalues for stationary state problems and to illustrate how to find the values of quantities (such as the phase shifts) that arise in the theory of scattering. Chapter-by-chapter treatment consists of analytical dynamics; optics, wave mecha

  12. Restricted total stability and total attractivity

    Directory of Open Access Journals (Sweden)

    Giuseppe Zappala'

    2006-08-01

    Full Text Available In this paper the new concepts of restricted total stability and total attractivity is formulated. For this purpose the classical theory of Malkin with suitable changes and the theory of limiting equations, introduced by Sell developed by Artstein and Andreev, are used. Significant examples are presented.

  13. 浙江来水与黄浦江上游支流总磷和氨氮变化规律分析%The Water from Zhejiang into Upstream Tributary of the Huangpu River Total Phosphorus, Ammonia Nitrogen Variation Law of Analysis

    Institute of Scientific and Technical Information of China (English)

    魏善发

    2012-01-01

    This paper analyzes the variation laws of the concentration of total phosphorus and ammonia- nitrogen both on the same section as the different seasons of Abundant, usual and dry water levels and also on the different sections in the same water season by the usage of SPSS statistical analysis software according to the monitoring data of ten years (2000-2009 ) of total phosphorus and ammonia on the three sections imported from the Zhejiang upstream to the Huangpu River. On the basis of the above analysis, the corresponding trend analysis used the method of Spearman rank correlation analysis reveals the variation laws and the trend of concentration of total phosphorus and ammonia at the different water seasons and sections.%利用浙江来水汇入黄浦江上游支流的3个断面2000-2009年10年的总磷和氨氮监测资料,分别对同一断面在丰水期、平水湖、枯水期的浓度以及同一水期不同断面的浓度,利用SPSS统计分析软件,对总磷、氨氮的浓度变化规律进行分析,在此基础上采用Spearman秩相关分析方法进行相应的趋势分析,揭示出总磷、氨氮在不同水期、不同断面的变化规律以及浓度变化趋势.

  14. Total variation approximation for quasi-equilibrium distributions, II

    CERN Document Server

    Barbour, A D

    2011-01-01

    Quasi-stationary distributions, as discussed by Darroch & Seneta (1965), have been used in biology to describe the steady state behaviour of population models which, while eventually certain to become extinct, nevertheless maintain an apparent stochastic equilibrium for long periods. These distributions have some drawbacks: they need not exist, nor be unique, and their calculation can present problems. In an earlier paper, we gave biologically plausible conditions under which the quasi-stationary distribution is unique, and can be closely approximated by distributions that are simple to compute. In this paper, we consider conditions under which the quasi-stationary distribution, if it exists, need not be unique, but an apparent stochastic equilibrium can nonetheless be identified and computed; we call such a distribution a quasi-equilibrium distribution.

  15. Total variation approximation for quasi-equilibrium distributions

    CERN Document Server

    Barbour, A D

    2010-01-01

    Quasi-stationary distributions, as discussed by Darroch & Seneta (1965), have been used in biology to describe the steady state behaviour of population models which, while eventually certain to become extinct, nevertheless maintain an apparent stochastic equilibrium for long periods. These distributions have some drawbacks: they need not exist, nor be unique, and their calculation can present problems. In this paper, we give biologically plausible conditions under which the quasi-stationary distribution is unique, and can be closely approximated by distributions that are simple to compute.

  16. The Total Variation Regularized L1 Model for Multiscale Decomposition

    Science.gov (United States)

    2006-01-01

    N00014-03-1- 0514, and DOE Grant GE-FG01-92ER-25126. †Department of Industrial Engineering and Operations Research, Columbia University, New York, NY...5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Columbia University,Department of Industrial Engineering and Operations...2r . THE TV-L1 MODEL FOR MULTISCALE DECOMPOSITION 5 In general the minimizer of the TV-L1 is nonunique . In the above disk example, if λ = 2/r

  17. A generalized vector-valued total variation algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Wohlberg, Brendt [Los Alamos National Laboratory; Rodriguez, Paul [PONTIFICIA UNIV

    2009-01-01

    We propose a simple but flexible method for solving the generalized vector-valued TV (VTV) functional, which includes both the {ell}{sup 2}-VTV and {ell}{sup 1}-VTV regularizations as special cases, to address the problems of deconvolution and denoising of vector-valued (e.g. color) images with Gaussian or salt-andpepper noise. This algorithm is the vectorial extension of the Iteratively Reweighted Norm (IRN) algorithm [I] originally developed for scalar (grayscale) images. This method offers competitive computational performance for denoising and deconvolving vector-valued images corrupted with Gaussian ({ell}{sup 2}-VTV case) and salt-and-pepper noise ({ell}{sup 1}-VTV case).

  18. Total Variation Regularization of Matrix-Valued Images

    Directory of Open Access Journals (Sweden)

    Oddvar Christiansen

    2007-01-01

    Blomgren and Chan in 1998. We treat the diffusion matrix D implicitly as the product D=LLT, and work with the elements of L as variables, instead of working directly on the elements of D. This ensures positive definiteness of the tensor during the regularization flow, which is essential when regularizing DTI. We perform numerical experiments on both synthetical data and 3D human brain DTI, and measure the quantitative behavior of the proposed model.

  19. Computerized Tomography with Total Variation and with Shearlets

    CERN Document Server

    Garduño, Edgar

    2016-01-01

    To reduce the x-ray dose in computerized tomography (CT), many constrained optimization approaches have been proposed aiming at minimizing a regularizing function that measures lack of consistency with some prior knowledge about the object that is being imaged, subject to a (predetermined) level of consistency with the detected attenuation of x-rays. Proponents of the shearlet transform in the regularizing function claim that the reconstructions so obtained are better than those produced using TV for texture preservation (but may be worse for noise reduction). In this paper we report results related to this claim. In our reported experiments using simulated CT data collection of the head, reconstructions whose shearlet transform has a small $\\ell_1$-norm are not more efficacious than reconstructions that have a small TV value. Our experiments for making such comparisons use the recently-developed superiorization methodology for both regularizing functions. Superiorization is an automated procedure for turning...

  20. A Robust Algorithm for Blind Total Variation Restoration

    Institute of Scientific and Technical Information of China (English)

    Jing Xu; Qian-shun Chang

    2008-01-01

    Image restoration is a fundamental problem in image processing. Blind image restoration has a great value in its practical application. However, it is not an easy problem to solve due to its complexity and difficulty. In this paper, we combine our robust algorithm for known blur operator with an alternating minimization implicit iterative scheme to deal with blind deconvolution problem, recover the image and identify the point spread function(PSF). The only assumption needed is satisfy the practical physical sense. Numerical experiments demonstrate that this minimization algorithm is efficient and robust over a wide range of PSF and have almost the same results compared with known PSF algorithm.

  1. High-Order Spectral Volume Method for 2D Euler Equations

    Science.gov (United States)

    Wang, Z. J.; Zhang, Laiping; Liu, Yen; Kwak, Dochan (Technical Monitor)

    2002-01-01

    The Spectral Volume (SV) method is extended to the 2D Euler equations. The focus of this paper is to study the performance of the SV method on multidimensional non-linear systems. Implementation details including total variation diminishing (TVD) and total variation bounded (TVB) limiters are presented. Solutions with both smooth features and discontinuities are utilized to demonstrate the overall capability of the SV method.

  2. Total Productive Maintenance at Paccar INC

    OpenAIRE

    2010-01-01

    This paper reports the application of total productive maintenance method at Paccar Inc. truck’s plant in Victoria, Australia. The total productive maintenance method and total productive maintenance house are presented. The global equipment effectiveness is computed and exemplified. The production structure and organising maintenance are presented. Resultas of the variation of global equipment effectiveness and autonomous maintenance in a two weeks period of time are reported.

  3. Total Productive Maintenance at Paccar INC

    Directory of Open Access Journals (Sweden)

    Ştefan Farkas

    2010-06-01

    Full Text Available This paper reports the application of total productive maintenance method at Paccar Inc. truck’s plant in Victoria, Australia. The total productive maintenance method and total productive maintenance house are presented. The global equipment effectiveness is computed and exemplified. The production structure and organising maintenance are presented. Resultas of the variation of global equipment effectiveness and autonomous maintenance in a two weeks period of time are reported.

  4. Variação de carboidratos e ácido cianídrico em raízes de mandioca, após a poda da parte aérea Carbohydrates and hydrocyanic acid variation in cassava roots which aereal portions were totally pruned

    Directory of Open Access Journals (Sweden)

    José Osmar Lorenzi

    1978-01-01

    Full Text Available São relatados resultados do estudo da variação de matéria seca, HCN, amido, carboidratos solúveis totais e açúcares redutores em raízes de mandioca (Manihot esculenta, Crantz nos dias que sucederam à poda ou remoção total da parte aérea. Na amostragem foi utilizado o método convencional: raízes tomadas ao acaso e representativas da população. Diferentes tipos de raízes (da base e meio da maniva e da base das hastes coletadas 17 dias após a poda apresentaram teores de carboidratos bem diferentes, seja pela mobi-lização mais acentuada de reservas, seja pela sua constituição originalmente diversa, o que sugere pesquisas mais detalhadas sobre o método de amostragem das raízes para análise de laboratório. Verificou-se que, num período de quatorze dias após a poda de plantas com treze meses de idade e em época quente e chuvosa, as transformações mais profundas ocorreram no teor de amido, que decresceu de 79,06% para 62,52%, e nos carboidratos solúveis totais e açúcares redutores, que tiveram um incremento na matéria seca das raízes, respectiva-mente de 7,65% e 1,55% para 17,56% e 5,03%. 0 teor de carboidratos totais foi pouco afetado pela poda, Indicando perda pequena destinada a nova brotação ou a outros processos fisiológicos. O teor de HCN decresceu de 67 para 35 ppm.Data are presented on the variation of the level of dry matter, cyanide, starch, total soluble carbohydrates, and reducing sugars content in roots of 13 months old cassava (Manihot esculenta, Crantz at successive stages after the total removal of the aereal portions. During the 14 days following pruning starch percentage decreased from 79.06% to 62.52%; total soluble carbohydrates and reducing sugars showed a variation from 7.65% and 1.55% up to 17.56% and 5.03% respectively. Total carbohydrate presented small losses by pruning probably due to the new sprouting process. Root cyanid content decreased from 67 to 35 ppm. Its has also been observed

  5. Qualidade total do produto Products total quality

    Directory of Open Access Journals (Sweden)

    Henrique Silveira de Almeida

    1992-06-01

    Full Text Available O texto aborda o conceito de qualidade total do produto, seus determinantes, bem como as dimensões que compõem essa qualidade. Parte-se do pressuposto de que a qualidade do produto deve ser avaliada pela satisfação total do consumidor. Para o consumidor a qualidade do produto envolve pelo menos as seguintes dimensões: a qualidade do produto em si; a qualidade do produto ao longo do tempo; a qualidade dos serviços associados ao uso do produto; e o custo do ciclo de vida do produto. O trabalho procura detalhar e discutir cada uma dessas dimensões da qualidade, tendo em vista a satisfação do consumidor.The paper concerns to the concept of product's total quality, its determinants, and the dimensions wich constitute this quality. We admit that product quality should be evaluated via consumer's total satisfaction. Product quality for consumers includes at least the following dimensions: the product quality per se; the performance of product quality over time; the quality of services related to the use of the product; and the product lifecycle costs. This study seeks to specify and to discuss each of these quality dimensions related to consumer's satisfaction.

  6. Total abdominal colectomy

    Science.gov (United States)

    ... the rectum. This can cause an infection or abscess. Scarring of the connection between the small intestine ... More Crohn disease Ileostomy Total proctocolectomy and ileal - anal pouch Total proctocolectomy with ileostomy Ulcerative colitis Patient ...

  7. Total parenteral nutrition - infants

    Science.gov (United States)

    ... medlineplus.gov/ency/article/007239.htm Total parenteral nutrition - infants To use the sharing features on this page, please enable JavaScript. Total parenteral nutrition (TPN) is a method of feeding that bypasses ...

  8. Total parenteral nutrition

    Science.gov (United States)

    ... medlineplus.gov/ency/patientinstructions/000177.htm Total parenteral nutrition To use the sharing features on this page, please enable JavaScript. Total parenteral nutrition (TPN) is a method of feeding that bypasses ...

  9. Reemplazo total de cadera

    OpenAIRE

    Sánchez Vergel, Alfredo; Fundación Valle de Lili

    2002-01-01

    Definición/Tipos de prótesis/ ¿Qué pacientes se podrían beneficiar de un reemplazo total de cadera?/Artrosis de cadera/Tipos de artrosis de cadera/Alternativas al reemplazo total de cadera/Preguntas frecuentes sobre el reemplazo total de cadera.

  10. Reemplazo total de cadera

    OpenAIRE

    Sánchez Vergel, Alfredo; Fundación Valle de Lili

    2002-01-01

    Definición/Tipos de prótesis/ ¿Qué pacientes se podrían beneficiar de un reemplazo total de cadera?/Artrosis de cadera/Tipos de artrosis de cadera/Alternativas al reemplazo total de cadera/Preguntas frecuentes sobre el reemplazo total de cadera.

  11. Total well dominated trees

    DEFF Research Database (Denmark)

    Finbow, Arthur; Frendrup, Allan; Vestergaard, Preben D.

    cardinality then G is a total well dominated graph. In this paper we study composition and decomposition of total well dominated trees. By a reversible process we prove that any total well dominated tree can both be reduced to and constructed from a family of three small trees....

  12. An total variational two norm finite difference wavelet domain inpainting algorithm in ultrasonic imaging logging%一种全变分二范数有限差分小波域超声成像测井修正算法

    Institute of Scientific and Technical Information of China (English)

    张健; 王一举; 余华平

    2015-01-01

    针对超声成像测井中由于各种不确定因素而导致测井图像中出现带状异常区域的现象,通过分析目前修复异常区域所采用的常规方法,尤其是小波域修复方法的不足,提出一种能够有效解决该类问题的全变分二范数有限差分小波域超声测井图像修正算法。首先,设计了基于图像基于相邻行相关值与绝对误差值相结合的“链条”异常区域自动识别算法,实现对异常区域的准确定位。随后针对全变分小波域图像修复过程中出现的“分片常数”效应的影响,设计了一种全变分二范数有限差分小波域修复算法来有效消除该影响。通过实际测井资料处理结果与标准测井图像进行的效果比对证明,所提算法进一步提升了针对“链条”异常区域的修复效果,为后期图像资料中该类状况的修复提供了有效的解决方案。%Aiming at the phenomenon that in the process of ultrasonic image logging,some zonal anomaly area will appear in the images due to several uncertain factors,this paper analyzes the inefficiency of normal ways including wavelet domain restoration way especially to clear away the zonal anomaly area so as to put forward an effective total-variation norm two finite difference ul-trasonic logging images in wavelet domain inpainting algorithm to solve this kind of issue.Firstly,a kind of automatic recognition algorithm about chain abnormal region based on adjacent rows and absolute error value combination was proposed,which realize the accurate location of imaging zonal region effectively.Then,Aiming at the total-variation wavelet domain image restoration in the presence of"piecewise constant"effect,for which the total variational norm two finite difference ultrasonic logging images in wavelet domain inpainting algorithm was proposed to eliminate the impact effectively.By comparing the experimental results in the actual logging image data processing

  13. Incapacidad laboral total

    Directory of Open Access Journals (Sweden)

    Orlando Díaz Tabares

    1997-04-01

    Full Text Available Se realizó un estudio longitudinal, descriptivo y retrospectivo con el objetivo de conocer el comportamiento de la incapacidad permanente para el trabajo en el municipio "San Cristóbal" durante el decenio 1982-1991, y se aplicó el método de encuesta por el que se recogieron datos que fueron extraídos del modelo oficial de peritaje médico laboral y de la entrevista con el peritado. Los resultados fueron plasmados en tablas de contingencias donde se relacionan las variables por cada año estudiado, y se aplicó la prueba estadística de chi cuadrado. El número de individuos dictaminados con incapacidad laboral total fue de 693; predominó en reportes el año 1988 con 114 casos y muy discretamente el sexo femenino sobre el masculino, el grupo etáreo de 45 a 54 años con 360 casos y la artrosis como entidad valorada por ortopedia, con análisis estadísticos significativos. No resultó estadísticamente significativo, el predominio de la hipertensión arterial sistémica entre las entidades valoradas por la especialidad de medicina interna como causas de incapacidad laboral. Fue muy significativa la variación del número de dictaminados por la comisión en cada uno de los años estudiados y que el porcentaje de ellos que se encontraban realizando trabajos que demandan esfuerzo físico de moderado a intenso al momento de aplicar la encuesta, ascendió al 64,9.A longitudinal, descriptive and retrospective study was conducted in order to know the behavior of permanent labor disability at the municipality of San Cristóbal during 1982-1991. A survey was done to collect data taken from the official model of medical inspections and from the interview with the disabled worker. The results were shown in contingency tables where the variables are related by every year studied. The chi square statistical test was applied. The number of individuals with labor disability was 693. As for reports, the year 1988 predominated with 114. There was a discreet

  14. Revision Total Elbow Arthroplasty.

    Science.gov (United States)

    Ramirez, Miguel A; Cheung, Emilie V; Murthi, Anand M

    2017-08-01

    Despite recent technologic advances, total elbow arthroplasty has complication rates higher than that of total joint arthroplasty in other joints. With new antirheumatic treatments, the population receiving total elbow arthroplasty has shifted from patients with rheumatoid arthritis to those with posttraumatic arthritis, further compounding the high complication rate. The most common reasons for revision include infection, aseptic loosening, fracture, and component failure. Common mechanisms of total elbow arthroplasty failure include infection, aseptic loosening, fracture, component failure, and instability. Tension band fixation, allograft struts with cerclage wire, and/or plate and screw constructs can be used for fracture stabilization.

  15. Totalization Data Exchange (TDEX)

    Data.gov (United States)

    Social Security Administration — The Totalization Data Exchange (TDEX) process is an exchange between SSA and its foreign country partners to identify deaths of beneficiaries residing abroad. The...

  16. Total N, total P and organic matters content in floodplain soils of Xianghai Nature Reserve

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Soil sediment samples of 10 layers with a spacing of 10 cm each were collected in different floodplain zones adjacent to Huolin River in the Xianghai Nature Reserve, and contents of total N, total P and organic matters were analyzed. The results showed that contents of total N, total P and organic matters were generally decreasing with the increase of distance from sample locations to the river channel, and contents of the three items were generally higher in the upper soil layer than that in the lower soil layer. The content variations displayed how flooding functions influenced nutrient matter content variations in floodplain soils since the flood inundation frequencies of the sample locations varied. The correlation analysis displayed that there were remarkable relativities between total N, total P and organic matters within definite spatial distance from the Huolin River channel.

  17. Strictness and Totality Analysis

    DEFF Research Database (Denmark)

    Solberg, K. L.; Nielson, Hanne Riis; Nielson, Flemming

    1998-01-01

    We define a novel inference system for strictness and totality analysis for the simply-typed lazy lambda-calculus with constants and fixpoints. Strictness information identifies those terms that definitely denote bottom (i.e. do not evaluate to WHNF) whereas totality information identifies those ...

  18. Genoptraening efter total knaealloplastik

    DEFF Research Database (Denmark)

    Holm, Bente; Kehlet, Henrik

    2009-01-01

    The short- and long-term benefits of post-discharge physiotherapy regimens after total knee arthroplasty are debatable. A national survey including hospitals in Denmark that perform total knee arthroplasty showed a large variability in indication and regimen for post-knee arthroplasty rehabilitat...

  19. Laparoscopic total pancreatectomy

    Science.gov (United States)

    Wang, Xin; Li, Yongbin; Cai, Yunqiang; Liu, Xubao; Peng, Bing

    2017-01-01

    Abstract Rationale: Laparoscopic total pancreatectomy is a complicated surgical procedure and rarely been reported. This study was conducted to investigate the safety and feasibility of laparoscopic total pancreatectomy. Patients and Methods: Three patients underwent laparoscopic total pancreatectomy between May 2014 and August 2015. We reviewed their general demographic data, perioperative details, and short-term outcomes. General morbidity was assessed using Clavien–Dindo classification and delayed gastric emptying (DGE) was evaluated by International Study Group of Pancreatic Surgery (ISGPS) definition. Diagnosis and Outcomes: The indications for laparoscopic total pancreatectomy were intraductal papillary mucinous neoplasm (IPMN) (n = 2) and pancreatic neuroendocrine tumor (PNET) (n = 1). All patients underwent laparoscopic pylorus and spleen-preserving total pancreatectomy, the mean operative time was 490 minutes (range 450–540 minutes), the mean estimated blood loss was 266 mL (range 100–400 minutes); 2 patients suffered from postoperative complication. All the patients recovered uneventfully with conservative treatment and discharged with a mean hospital stay 18 days (range 8–24 days). The short-term (from 108 to 600 days) follow up demonstrated 3 patients had normal and consistent glycated hemoglobin (HbA1c) level with acceptable quality of life. Lessons: Laparoscopic total pancreatectomy is feasible and safe in selected patients and pylorus and spleen preserving technique should be considered. Further prospective randomized studies are needed to obtain a comprehensive understanding the role of laparoscopic technique in total pancreatectomy. PMID:28099344

  20. Plant responses to climatic extremes: within-species variation equals among-species variation

    DEFF Research Database (Denmark)

    Malyshev, Andrey; Arfin Kahn, Mohammed A.S.; Beierkuhnlein, Carl

    2016-01-01

    , root 15N uptake, and live and dead tissue mass. Using coefficients of variation (CVs) for each experiment and response parameter, a total of 156 within- vs. among-species comparisons were conducted, comparing within-species variation in each of four species with among- species variation for each seed......) and for practical applications (e.g., biodiversity conservation)....

  1. Estonian total ozone climatology

    Directory of Open Access Journals (Sweden)

    K. Eerme

    Full Text Available The climatological characteristics of total ozone over Estonia based on the Total Ozone Mapping Spectrometer (TOMS data are discussed. The mean annual cycle during 1979–2000 for the site at 58.3° N and 26.5° E is compiled. The available ground-level data interpolated before TOMS, have been used for trend detection. During the last two decades, the quasi-biennial oscillation (QBO corrected systematic decrease of total ozone from February–April was 3 ± 2.6% per decade. Before 1980, a spring decrease was not detectable. No decreasing trend was found in either the late autumn ozone minimum or in the summer total ozone. The QBO related signal in the spring total ozone has an amplitude of ± 20 DU and phase lag of 20 months. Between 1987–1992, the lagged covariance between the Singapore wind and the studied total ozone was weak. The spring (April–May and summer (June–August total ozone have the best correlation (coefficient 0.7 in the yearly cycle. The correlation between the May and August total ozone is higher than the one between the other summer months. Seasonal power spectra of the total ozone variance show preferred periods with an over 95% significance level. Since 1986, during the winter/spring, the contribution period of 32 days prevails instead of the earlier dominating 26 days. The spectral densities of the periods from 4 days to 2 weeks exhibit high interannual variability.

    Key words. Atmospheric composition and structure (middle atmosphere – composition and chemistry; volcanic effects – Meteorology and atmospheric dynamics (climatology

  2. Total Water Management - slides

    Science.gov (United States)

    Total Water Management (TWM) examines urban water systems in an interconnected manner. It encompasses reducing water demands, increasing water recycling and reuse, creating water supply assets from stormwater management, matching water quality to end-use needs, and achieving envi...

  3. Total 2004 results

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-02-01

    This document presents the 2004 results of Total Group: consolidated account, special items, number of shares, market environment, adjustment for amortization of Sanofi-Aventis merger-related intangibles, 4. quarter 2004 results (operating and net incomes, cash flow), upstream (results, production, reserves, recent highlights), downstream (results, refinery throughput, recent highlights), chemicals (results, recent highlights), Total's full year 2004 results (operating and net income, cash flow), 2005 sensitivities, Total SA parent company accounts and proposed dividend, adoption of IFRS accounting, summary and outlook, main operating information by segment for the 4. quarter and full year 2004: upstream (combined liquids and gas production by region, liquids production by region, gas production by region), downstream (refined product sales by region, chemicals), Total financial statements: consolidated statement of income, consolidated balance sheet (assets, liabilities and shareholder's equity), consolidated statements of cash flows, business segments information. (J.S.)

  4. Revised Total Coliform Rule

    Science.gov (United States)

    The Revised Total Coliform Rule (RTCR) aims to increase public health protection through the reduction of potential pathways for fecal contamination in the distribution system of a public water system (PWS).

  5. Total Ecosystem Carbon Stock

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Total ecosystem carbon includes above- and below-ground live plant components (such as leaf, branch, stem and root), dead biomass (such as standing dead wood, down...

  6. Total lymphoid irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Sutherland, D.E.; Ferguson, R.M.; Simmons, R.L.; Kim, T.H.; Slavin, S.; Najarian, J.S.

    1983-05-01

    Total lymphoid irradiation by itself can produce sufficient immunosuppression to prolong the survival of a variety of organ allografts in experimental animals. The degree of prolongation is dose-dependent and is limited by the toxicity that occurs with higher doses. Total lymphoid irradiation is more effective before transplantation than after, but when used after transplantation can be combined with pharmacologic immunosuppression to achieve a positive effect. In some animal models, total lymphoid irradiation induces an environment in which fully allogeneic bone marrow will engraft and induce permanent chimerism in the recipients who are then tolerant to organ allografts from the donor strain. If total lymphoid irradiation is ever to have clinical applicability on a large scale, it would seem that it would have to be under circumstances in which tolerance can be induced. However, in some animal models graft-versus-host disease occurs following bone marrow transplantation, and methods to obviate its occurrence probably will be needed if this approach is to be applied clinically. In recent years, patient and graft survival rates in renal allograft recipients treated with conventional immunosuppression have improved considerably, and thus the impetus to utilize total lymphoid irradiation for its immunosuppressive effect alone is less compelling. The future of total lymphoid irradiation probably lies in devising protocols in which maintenance immunosuppression can be eliminated, or nearly eliminated, altogether. Such protocols are effective in rodents. Whether they can be applied to clinical transplantation remains to be seen.

  7. 不同农田施肥方式下土壤碳氮变化特征及其环境意义%The Variation Characteristics of Soil Organic Carbon and Total Nitrogen in Paddy Field and Its Environmental Effect Under Different Fertilization Patterns

    Institute of Scientific and Technical Information of China (English)

    张刚; 王德建; 王灿

    2013-01-01

    In order to identify the variation characteristics of soil organic carbon and total nitrogen in paddy field and its impact on the environment under different fertilization patterns, an investigation was carried out to study the changes in soil organic carbon (SOC) and total nitrogen (TN) as affected by long-term fertilizations of zero fertilizer, NPK fertilizer alone and NPK with straw incorporation in rice-wheat cropping system in paddy soil in Taihu Region. The results showed that the SOC and TN over the soil profile were characterized by a gradual decrease from the top to bottom, and the effect of straw-returning was mainly in the top 0-10 cm soil layer. Both the contents of SOC and TN increased in treatment of NPK fertilizer alone and NPK with straw incorporation, and decreased significantly in zero fertilizer treatment. The increasing of SOC and TN wasn’t significant in NPK fertilizer treatment, but SOC and TN increased significantly in treatment of NPK with straw, being 35.8%and 17.3%respectively during four years. SOC and TN had the same variation trend, which was a significant positive correlation (R2=0.78, P<0.01). The C/N ratio of soils was around 10.0 in Taihu Region, which declined in the past 20 years. Treatment of NPK with straw incorporation could increase the C/N ratio of soil and promote the soil carbon-nitrogen cycling. These results indicated that pattern of NPK with straw incorporation could improve the soil physical chemistry property to enhance the farmland productivity and be worth extrapolating.%为了明确不同农田施肥方式对土壤碳氮变化及其对环境的影响,通过长期定位试验研究了不同施肥方式下土壤碳氮变化特征。结果表明:土壤有机碳、全氮在土壤剖面中呈上高下低趋势,秸秆还田作用主要发生在0~10 cm处的耕层;单施化肥和化肥配施秸秆均能增加土壤有机碳、全氮含量,长期无肥处理的土壤有机碳、全氮含量明显下降,单施

  8. Total Energy Monitor

    Energy Technology Data Exchange (ETDEWEB)

    Friedrich, S

    2008-08-11

    The total energy monitor (TE) is a thermal sensor that determines the total energy of each FEL pulse based on the temperature rise induced in a silicon wafer upon absorption of the FEL. The TE provides a destructive measurement of the FEL pulse energy in real-time on a pulse-by-pulse basis. As a thermal detector, the TE is expected to suffer least from ultra-fast non-linear effects and to be easy to calibrate. It will therefore primarily be used to cross-calibrate other detectors such as the Gas Detector or the Direct Imager during LCLS commissioning. This document describes the design of the TE and summarizes the considerations and calculations that have led to it. This document summarizes the physics behind the operation of the Total Energy Monitor at LCLS and derives associated engineering specifications.

  9. Algebraic totality, towards completeness

    CERN Document Server

    Tasson, Christine

    2009-01-01

    Finiteness spaces constitute a categorical model of Linear Logic (LL) whose objects can be seen as linearly topologised spaces, (a class of topological vector spaces introduced by Lefschetz in 1942) and morphisms as continuous linear maps. First, we recall definitions of finiteness spaces and describe their basic properties deduced from the general theory of linearly topologised spaces. Then we give an interpretation of LL based on linear algebra. Second, thanks to separation properties, we can introduce an algebraic notion of totality candidate in the framework of linearly topologised spaces: a totality candidate is a closed affine subspace which does not contain 0. We show that finiteness spaces with totality candidates constitute a model of classical LL. Finally, we give a barycentric simply typed lambda-calculus, with booleans ${\\mathcal{B}}$ and a conditional operator, which can be interpreted in this model. We prove completeness at type ${\\mathcal{B}}^n\\to{\\mathcal{B}}$ for every n by an algebraic metho...

  10. [Total temporomandibular joint prostheses].

    Science.gov (United States)

    Zwetyenga, N; Amroun, S; Wajszczak, B-L; Moris, V

    2016-09-01

    The temporomandibular joint (TMJ) is probably the most complex human joint. As in all joints, its prosthetic replacement may be indicated in selected cases. Significant advances have been made in the design of TMJ prostheses during the last three decades and the indications have been clarified. The aim of our work was to make an update on the current total TMJ total joint replacement. Indications, contraindications, prosthetic components, advantages, disadvantages, reasons for failure or reoperation, virtual planning and surgical protocol have been exposed. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  11. Total Quality Management Simplified.

    Science.gov (United States)

    Arias, Pam

    1995-01-01

    Maintains that Total Quality Management (TQM) is one method that helps to monitor and improve the quality of child care. Lists four steps for a child-care center to design and implement its own TQM program. Suggests that quality assurance in child-care settings is an ongoing process, and that TQM programs help in providing consistent, high-quality…

  12. Total versus subtotal hysterectomy

    DEFF Research Database (Denmark)

    Gimbel, Helga; Zobbe, Vibeke; Andersen, Anna Birthe;

    2005-01-01

    The aim of this study was to compare total and subtotal abdominal hysterectomy for benign indications, with regard to urinary incontinence, postoperative complications, quality of life (SF-36), constipation, prolapse, satisfaction with sexual life, and pelvic pain at 1-year postoperative. Eighty...

  13. Total Quality Management Simplified.

    Science.gov (United States)

    Arias, Pam

    1995-01-01

    Maintains that Total Quality Management (TQM) is one method that helps to monitor and improve the quality of child care. Lists four steps for a child-care center to design and implement its own TQM program. Suggests that quality assurance in child-care settings is an ongoing process, and that TQM programs help in providing consistent, high-quality…

  14. Total Quality Management Seminar.

    Science.gov (United States)

    Massachusetts Career Development Inst., Springfield.

    This booklet is one of six texts from a workplace literacy curriculum designed to assist learners in facing the increased demands of the workplace. The booklet contains seven sections that cover the following topics: (1) meaning of total quality management (TQM); (2) the customer; (3) the organization's culture; (4) comparison of management…

  15. Total hip arthroplasty

    Directory of Open Access Journals (Sweden)

    Slavković Nemanja

    2012-01-01

    Full Text Available Total hip arthroplasty is most common reconstructive hip procedure in adults. In this surgery we replace some parts of the upper femur and acetabulum with biocompatible materials. The main goal of this surgery is to eliminate pain and regain full extent of joint motion, maintaining hip stability. Surgical technique, biomaterials, design of the prosthesis and fixation techniques have evolved with time adjusting to each other. After total hip arthroplasty patients’ quality of life should be improved. There are many various postoperative complications. Some of them are fatal, and some are minor, which may become manifested years after surgery. Each next surgical procedure following previous hip surgery is associated with considerably lower chances to be successful. Therefore, in primary total hip arthroplasty, preoperative evaluation and preparation of patients are essential. Every orthopaedic surgeon needs to improve already adopted surgical skills applying them with precision and without compromise, with the main goal to achieve long-term durability of the selected implant. The number of total hip arthroplasties will also increase in future, and newer and higher quality materials will be used.

  16. CSF total protein

    Science.gov (United States)

    CSF total protein is a test to determine the amount of protein in your spinal fluid, also called cerebrospinal fluid (CSF). ... The normal protein range varies from lab to lab, but is typically about 15 to 60 milligrams per deciliter (mg/dL) ...

  17. Total Cost of Ownership

    DEFF Research Database (Denmark)

    Zachariassen, Frederik

    2007-01-01

    Total Cost of Ownership (TCO), som giver et bud på, hvordan virksomheder kan opnå en bedre indsigt i, hvilke leverandører der forårsager hvilke omkostninger og dermed danne et forbedret beslutningsgrundlag for besparelser i leverandørleddet. I artiklen argumenteres først og fremmest for, hvorfor TCO er...

  18. Supravaginal eller total hysterektomi?

    DEFF Research Database (Denmark)

    Edvardsen, L; Madsen, E M

    1994-01-01

    is examined. It is concluded that the risk of developing carcinoma of the cervical stump is low, and no longer a weighty indication for the total in preference to the supravaginal hysterectomy as long as subsequent screening of the cervix is performed. At the same time it is important to inform the women...

  19. Total synthesis of aquatolide

    NARCIS (Netherlands)

    Saya, J.M.; Vos, K.; Klein Nijenhuis, R.A.; van Maarseveen, J.H.; Ingemann, S.; Hiemstra, H.

    2015-01-01

    A total synthesis of the sesquiterpene lactone aquatolide has been accomplished. The central step is an intramolecular [2 + 2]-photocycloaddition of an allene onto an alpha,beta-unsaturated delta-lactone. Other key steps are an intramolecular Horner-Wadsworth-Emmons reaction to close the lactone and

  20. Total knee arthroplasty

    DEFF Research Database (Denmark)

    Schrøder, Henrik M.; Petersen, Michael M.

    2016-01-01

    Total knee arthroplasty (TKA) is a successful treatment of the osteoarthritic knee, which has increased dramatically over the last 30 years. The indication is a painful osteoarthritic knee with relevant radiographic findings and failure of conservative measures like painkillers and exercise. Trea...

  1. Total Synthesis of Naloxone

    Institute of Scientific and Technical Information of China (English)

    HU Wen-Xiang; WANG Jian-Ying; XU Ming

    2003-01-01

    @@ Naloxone (1) is one of the 14-hydroxyl substituted opium antagonists which are valuable medications for treat ment of opiate abuse, opiate overdose, and alcohol addiction. Here, the total synthesis of naloxone was described. We selected 2,6-dihydroxynaphalene (2) as the starting material.

  2. Total Quality Management.

    Science.gov (United States)

    Focus in Change, 1992

    1992-01-01

    The philosophy known as Total Quality Management (TQM) is frequently presented as a way to change and improve public education. This issue of "Focus in Change" examines Deming's original 14 TQM points and their application to education. Myron Tribus lays out the core philosophy of the movement and discusses its possible application to…

  3. Models of Solar Irradiance Variations: Current Status

    Indian Academy of Sciences (India)

    Natalie A. Krivova; Sami K. Solanki

    2008-03-01

    Regular monitoring of solar irradiance has been carried out since 1978 to show that solar total and spectral irradiance varies at different time scales. Whereas variations on time scales of minutes to hours are due to solar oscillations and granulation, variations on longer time scales are driven by the evolution of the solar surface magnetic field. Here the most recent advances in modelling of solar irradiance variations on time scales longer than a day are briefly reviewed.

  4. Total design of participation

    DEFF Research Database (Denmark)

    Munch, Anders V.

    2016-01-01

    The idea of design as an art made not only for the people, but also by the people is an old dream going back at least to William Morris. It is, however, reappearing vigoriously in many kinds of design activism and grows out of the visions of a Total Design of society. The ideas of participation...... by Tim Brown can be compared to considerations by László Moholy-Nagy and Walter Gropuis on the training and education of active and capable citizens. This opens, though, some dilemmas to discuss: To what extend is the capability of creativity then a (pre)condition to be a citizen of the society wished...... for? To which degree should everyone be educated in ’design literacy’ to participate? Total design of participation is an artistic intervention in society and must be discussed in this utopian tradition....

  5. Total Synthesis of (-)-Conolutinine.

    Science.gov (United States)

    Feng, Xiangyang; Jiang, Guangde; Xia, Zilei; Hu, Jiadong; Wan, Xiaolong; Gao, Jin-Ming; Lai, Yisheng; Xie, Weiqing

    2015-09-18

    The first enantioselective synthesis of (-)-conolutinine was achieved in 10 steps. The synthesis featured a catalytic asymmetric bromocyclization of tryptamine to forge the tricycle intermediate. Hydration of an alkene catalyzed by Co(acac)2 was also employed as a key step to diastereoselectively introduce the tertiary alcohol moiety. The absolute configuration of (-)-conolutinine was established to be (2S,5aS,8aS,13aR) based on this asymmetric total synthesis.

  6. Cervical Total Disc Arthroplasty

    OpenAIRE

    Basho, Rahul; Hood, Kenneth A.

    2012-01-01

    Symptomatic adjacent segment degeneration of the cervical spine remains problematic for patients and surgeons alike. Despite advances in surgical techniques and instrumentation, the solution remains elusive. Spurred by the success of total joint arthroplasty in hips and knees, surgeons and industry have turned to motion preservation devices in the cervical spine. By preserving motion at the diseased level, the hope is that adjacent segment degeneration can be prevented. Multiple cervical disc...

  7. TOTAL PERFORMANCE SCORECARD

    OpenAIRE

    Anca ȘERBAN; Oana DUMITRAȘCU

    2013-01-01

    The purpose of this paper is to present the evolution of the Balanced Scorecard from a measurement instrument to a strategic performance management tool and to highlight the advantages of implementing the Total Performance Scorecard, especially for Human Resource Management. The study has been accomplished using the methodology of bibliographic study and various secondary sources. Implementing the classical Balanced Scorecard indicated over the years, repeatedly failure. It can be indicated t...

  8. Total synthesis of teixobactin

    Science.gov (United States)

    Jin, Kang; Sam, Iek Hou; Po, Kathy Hiu Laam; Lin, Du'an; Ghazvini Zadeh, Ebrahim H.; Chen, Sheng; Yuan, Yu; Li, Xuechen

    2016-08-01

    To cope with the global bacterial multidrug resistance, scientific communities have devoted significant efforts to develop novel antibiotics, particularly those with new modes of actions. Teixobactin, recently isolated from uncultured bacteria, is considered as a promising first-in-class drug candidate for clinical development. Herein, we report its total synthesis by a highly convergent Ser ligation approach and this strategy allows us to prepare several analogues of the natural product.

  9. Sobredentadura total superior implantosoportada

    Directory of Open Access Journals (Sweden)

    Luis Orlando Rodríguez García

    2010-06-01

    Full Text Available Se presenta un caso de un paciente desdentado total superior, rehabilitado en la consulta de implantología de la Clínica "Pedro Ortiz" del municipio Habana del Este en Ciudad de La Habana, Cuba, en el año 2009, mediante prótesis sobre implantes osteointegrados, técnica que se ha incorporado a la práctica estomatológica en Cuba como alternativa al tratamiento convencional en los pacientes desdentados totales. Se siguió un protocolo que comprendió una fase quirúrgica, procedimiento con o sin realización de colgajo y carga precoz o inmediata. Se presenta un paciente masculino de 56 años de edad, que acudió a la consulta multidisciplinaria, preocupado, porque se le habían elaborado tres prótesis en los últimos dos años y ninguna reunía los requisitos de retención que él necesitaba para sentirse seguro y cómodo con las mismas. El resultado final fue la satisfacción total del paciente, con el mejoramiento de la calidad estética y funcional.

  10. Turbulence Model Effects on Cold-Gas Lateral Jet Interaction in a Supersonic Crossflow

    Science.gov (United States)

    2014-06-01

    symmetry of the geometry . The computational domains were meshed with MIME from Metacomp Technologies (18). In both computational domains, the forward...van Leer-Contact (HLLC) Riemann solver and a multidimensional Total-Variation-Diminishing (TVD) continuous flux limiter (19). The choice of... Riemann 10 problem at the boundary. For the cases modeling the wind tunnel wall, the cylindrical section of the outer boundary was modeled as a no

  11. Numerical Study of Shock Waves Propagating in a Rectangular Elbow : Effects of Area Reduction and Rounded Corner

    OpenAIRE

    1994-01-01

    In this paper, the shock wave propagating in a rectangular elbow and the transient flow induced by the shock were investigated numerically in order to clarify how the transmitted shock wave past the elbow is stabilized to uniformity by the effects of area reduction and the rounded corner. Computations were carried out by solving the two-dimensional compressible Navier-Stokes equations by using the total variation diminishing (TVD) scheme. Calculations were performed for three kinds of area re...

  12. A highly accurate method to solve Fisher’s equation

    Indian Academy of Sciences (India)

    Mehdi Bastani; Davod Khojasteh Salkuyeh

    2012-03-01

    In this study, we present a new and very accurate numerical method to approximate the Fisher’s-type equations. Firstly, the spatial derivative in the proposed equation is approximated by a sixth-order compact finite difference (CFD6) scheme. Secondly, we solve the obtained system of differential equations using a third-order total variation diminishing Runge–Kutta (TVD-RK3) scheme. Numerical examples are given to illustrate the efficiency of the proposed method.

  13. Total Quality Management in Higher Education: Applying Deming's Fourteen Points.

    Science.gov (United States)

    Masters, Robert J.; Leiker, Linda

    1992-01-01

    This article presents guidelines to aid administrators of institutions of higher education in applying the 14 principles of Total Quality Management. The principles stress understanding process improvements, handling variation, fostering prediction, and using psychology to capitalize on human resources. (DB)

  14. Total ankle joint replacement.

    Science.gov (United States)

    2016-02-01

    Ankle arthritis results in a stiff and painful ankle and can be a major cause of disability. For people with end-stage ankle arthritis, arthrodesis (ankle fusion) is effective at reducing pain in the shorter term, but results in a fixed joint, and over time the loss of mobility places stress on other joints in the foot that may lead to arthritis, pain and dysfunction. Another option is to perform a total ankle joint replacement, with the aim of giving the patient a mobile and pain-free ankle. In this article we review the efficacy of this procedure, including how it compares to ankle arthrodesis, and consider the indications and complications.

  15. Total quality accounting

    Directory of Open Access Journals (Sweden)

    Andrijašević Maja

    2008-01-01

    Full Text Available The focus of competitive "battle" shifted from the price towards non-price instruments, above all, towards quality that became the key variable for profitability increase and achievement of better comparative position of a company. Under such conditions, management of a company, which, according to the established and certified system of total quality, strives towards achieving of a better market position, faces the problem of quality cost measurement and determination. Management, above all, cost accounting can help in solving of this problem, but the question is how much of its potential is being used for that purpose.

  16. Total Logistic Plant Solutions

    Directory of Open Access Journals (Sweden)

    Dusan Dorcak

    2016-02-01

    Full Text Available The Total Logistics Plant Solutions, plant logistics system - TLPS, based on the philosophy of advanced control processes enables complex coordination of business processes and flows and the management and scheduling of production in the appropriate production plans and planning periods. Main attributes of TLPS is to create a comprehensive, multi-level, enterprise logistics information system, with a certain degree of intelligence, which accepts the latest science and research results in the field of production technology and logistics. Logistic model of company understands as a system of mutually transforming flows of materials, energy, information, finance, which is realized by chain activities and operations

  17. ANALYSIS AND ACCOUNTING OF TOTAL CASH FLOW

    Directory of Open Access Journals (Sweden)

    MELANIA ELENA MICULEAC

    2012-01-01

    Full Text Available In order to reach the objective of supplying some relevant information regarding the liquidity inflows and outflows during a financial exercise, the total cash flow analysis must include the analysis of result cashable from operation, of payments and receipts related to the investment and of financing decisions of the last exercise, as well as the analysis of treasury variation (of cash items. The management of total cash flows ensures the correlation of current liquidness flows as consequence of receipts with the payments ’flows, in order to provide payment continuity of mature obligations.

  18. Calculus of variations

    CERN Document Server

    Elsgolc, L E; Stark, M

    1961-01-01

    Calculus of Variations aims to provide an understanding of the basic notions and standard methods of the calculus of variations, including the direct methods of solution of the variational problems. The wide variety of applications of variational methods to different fields of mechanics and technology has made it essential for engineers to learn the fundamentals of the calculus of variations. The book begins with a discussion of the method of variation in problems with fixed boundaries. Subsequent chapters cover variational problems with movable boundaries and some other problems; sufficiency

  19. Identity and total institution

    Directory of Open Access Journals (Sweden)

    Ljubičić Milana

    2015-01-01

    Full Text Available This paper analyses a psychiatric institution resident’s identity (self- construction processes. Our quest was grounded on constructivist theoretical paradigm that sees identity as a manner a person defines oneself in accordance with offered social repertoire. In other words, the total institution milieu offers limited range of identities to its residents. On the other hand, the latter are not just passive subjects that identity is imposed upon. They are able to use a number of adjustment mechanisms to the knowledge about themselves - ranging from symbolic escape to open resistance against the imposed image about them; to obedience, and we were interested to understand the (supposed complex dynamic of identity (re-building in, so-called, special or forensic patients. In order to understand this process and attempting to discover, besides the manifest also the latent layer of the story about self, the local, or personal, identity understanding was examined.

  20. Total organic carbon analyzer

    Science.gov (United States)

    Godec, Richard G.; Kosenka, Paul P.; Smith, Brian D.; Hutte, Richard S.; Webb, Johanna V.; Sauer, Richard L.

    The development and testing of a breadboard version of a highly sensitive total-organic-carbon (TOC) analyzer are reported. Attention is given to the system components including the CO2 sensor, oxidation reactor, acidification module, and the sample-inlet system. Research is reported for an experimental reagentless oxidation reactor, and good results are reported for linearity, sensitivity, and selectivity in the CO2 sensor. The TOC analyzer is developed with gravity-independent components and is designed for minimal additions of chemical reagents. The reagentless oxidation reactor is based on electrolysis and UV photolysis and is shown to be potentially useful. The stability of the breadboard instrument is shown to be good on a day-to-day basis, and the analyzer is capable of 5 sample analyses per day for a period of about 80 days. The instrument can provide accurate TOC and TIC measurements over a concentration range of 20 ppb to 50 ppm C.

  1. Total System Performance Assessment

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Yong Soo; Kang, Chul Hyung; Lee, Youn Myoung; Han, Ji Woong; Choi, Jong Won; Hahn, Pil Soo; Park, Jeong Hwa; Jeong, Mi Seon

    2007-06-15

    Based on the KAERI FEP list developed through the previous studies, the KAERI FEP Encyclopedia has been developed. Current version is 1.0 which includes all relevant FEPs to compose of two references and all alternative scenarios. Many interaction FEPs between scenario defining FEP(SDF) are created throughout the study. FEPs are classified into many Integrated FEP(IFEP) which eventually become the elements of the RES matrix. The FEAS program one of the component of the KAERI's CYPRUS information system is added to develop the FEP, RES, AC, AMF and finally scenarios. It assists to create transparent way to deal with assessment from the stage of the planning of the R and D to the final stage of the external audit and regulatory body review. Even though MASCOT-K and compartment analysis codes such as AMBER, GoldSim and Ecolego are excellent for TSPA they by in heritage possess a certain limitation especially to identify a proper migration cross sectional area when a relatively big component intersects with a tiny one such as a fracture. It is truly 3D phenomena in nature. MDPSA code is developed which is expected to overcome limitations in compartment models while successfully deals with natural disruptive events. The R and D target for the TSPA is to develop the sufficient scenarios and their variation cases to understand the safety of KRS in every possible aspect. For this, reference scenarios, alternative scenarios covering engineered barrier failure and natural events are developed and assessed respectively for around 100 cases. The stylized template to assess the Korean reference biosphere is developed using the AMBER. Three critical groups, agricultural, freshwater and marine water fishing groups are identified to assess the DCF following the guidelines of ICRP. Based on the QA principles of T2R3, the web based QA system is developed using the procedures in the USNRC 10CFR50 Appendix B. The QA system is combined with the PAID and FEAS to create the

  2. Primary total elbow arthroplasty

    Directory of Open Access Journals (Sweden)

    Suresh Kumar

    2013-01-01

    Full Text Available Background: Primary total elbow arthroplasty (TEA is a challenging procedure for orthopedic surgeons. It is not performed as frequently as compared to hip or knee arthroplasty. The elbow is a nonweight-bearing joint; however, static loading can create forces up to three times the body weight and dynamic loading up to six times. For elderly patients with deformity and ankylosis of the elbow due to posttraumatic arthritis or rheumatoid arthritis or comminuted fracture distal humerus, arthroplasty is one of the option. The aim of this study is to analyze the role of primary total elbow arthroplasty in cases of crippling deformity of elbow. Materials and Methods: We analyzed 11 cases of TEA, between December 2002 and September 2012. There were 8 females and 3 males. The average age was 40 years (range 30-69 years. The indications for TEA were rheumatoid arthritis, comminuted fracture distal humerus with intraarticular extension, and posttraumatic bony ankylosis of elbow joint. The Baksi sloppy (semi constrained hinge elbow prosthesis was used. Clinico-radiological followup was done at 1 month, 3 months, 6 months, 1 year, and then yearly basis. Results: In the present study, average supination was 70° (range 60-80° and average pronation was 70° (range 60-80°. Average flexion was 135° (range 130-135°. However, in 5 cases, there was loss of 15 to 35° (average 25° of extension (45° out of 11 cases. The mean Mayo elbow performance score was 95.4 points (range 70-100. Arm length discrepancy was only in four patients which was 36% out of 11 cases. Clinico-radiologically all the elbows were stable except in one case and no immediate postoperative complication was noted. Radiolucency or loosening of ulnar stem was seen in 2 cases (18% out of 11 cases, in 1 case it was noted after 5 years and in another after 10 years. In second case, revision arthroplasty was done, in which only ulnar hinge section, hinge screw and lock screw with hexagonal head

  3. The total artificial heart.

    Science.gov (United States)

    Cook, Jason A; Shah, Keyur B; Quader, Mohammed A; Cooke, Richard H; Kasirajan, Vigneshwar; Rao, Kris K; Smallfield, Melissa C; Tchoukina, Inna; Tang, Daniel G

    2015-12-01

    The total artificial heart (TAH) is a form of mechanical circulatory support in which the patient's native ventricles and valves are explanted and replaced by a pneumatically powered artificial heart. Currently, the TAH is approved for use in end-stage biventricular heart failure as a bridge to heart transplantation. However, with an increasing global burden of cardiovascular disease and congestive heart failure, the number of patients with end-stage heart failure awaiting heart transplantation now far exceeds the number of available hearts. As a result, the use of mechanical circulatory support, including the TAH and left ventricular assist device (LVAD), is growing exponentially. The LVAD is already widely used as destination therapy, and destination therapy for the TAH is under investigation. While most patients requiring mechanical circulatory support are effectively treated with LVADs, there is a subset of patients with concurrent right ventricular failure or major structural barriers to LVAD placement in whom TAH may be more appropriate. The history, indications, surgical implantation, post device management, outcomes, complications, and future direction of the TAH are discussed in this review.

  4. Total disc replacement.

    Science.gov (United States)

    Vital, J-M; Boissière, L

    2014-02-01

    Total disc replacement (TDR) (partial disc replacement will not be described) has been used in the lumbar spine since the 1980s, and more recently in the cervical spine. Although the biomechanical concepts are the same and both are inserted through an anterior approach, lumbar TDR is conventionally indicated for chronic low back pain, whereas cervical TDR is used for soft discal hernia resulting in cervicobrachial neuralgia. The insertion technique must be rigorous, with precise centering in the disc space, taking account of vascular anatomy, which is more complex in the lumbar region, particularly proximally to L5-S1. All of the numerous studies, including prospective randomized comparative trials, have demonstrated non-inferiority to fusion, or even short-term superiority regarding speed of improvement. The main implant-related complication is bridging heterotopic ossification with resulting loss of range of motion and increased rates of adjacent segment degeneration, although with an incidence lower than after arthrodesis. A sufficiently long follow-up, which has not yet been reached, will be necessary to establish definitively an advantage for TDR, particularly in the cervical spine. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  5. Variational integrators in plasma physics

    Energy Technology Data Exchange (ETDEWEB)

    Kraus, Michael

    2013-07-01

    integrating factors and adjoint equations. It allows us to find a Lagrangian for all ordinary and partial differential equations and systems thereof, for which the number of variables equals the number of equations. Consequently, the applicability of the variational integrators is extended to a much larger family of systems as envisaged in the original theory. The theory allows for the application of Noether's theorem to analyse the conservation properties of the system, both at the continuous and the discrete level. In numerical examples, the conservation properties of the derived schemes are analysed. In case of guiding centre dynamics, momentum in the toroidal direction of a tokamak is preserved exactly. The particle energy exhibits an error, but the absolute value of this error stays constant during the entire simulation. Therefore numerical dissipation is absent. In case of the kinetic theory, the total number of particles, total linear momentum and total energy are preserved exactly, i.e., up to machine accuracy. In case of magnetohydrodynamics, the total energy, cross helicity and the divergence of the magnetic field are preserved up to machine precision. These conservation properties not only make the numerical schemes more stable than those obtained by traditional discretisation methods, but they also reduce unphysical behaviour like spurious loss of energy or momentum, thereby increasing the trustworthiness of numerical simulations.

  6. Functions of bounded variation

    OpenAIRE

    Lind, Martin

    2006-01-01

    The paper begins with a short survey of monotone functions. The functions of bounded variation are introduced and some basic properties of these functions are given. Finally the jump function of a function of bounded variation is defined.

  7. On the total mean curvature of non-rigid surfaces

    OpenAIRE

    Alexandrov, Victor

    2008-01-01

    Using Green's theorem we reduce the variation of the total mean curvature of a smooth surface in the Euclidean 3-space to a line integral of a special vector field and obtain the following well-known theorem as an immediate consequence: the total mean curvature of a closed smooth surface in the Euclidean 3-space is stationary under an infinitesimal flex.

  8. Studying Variation in Tunes

    NARCIS (Netherlands)

    Janssen, B.; van Kranenburg, P.

    2014-01-01

    Variation in music can be caused by different phenomena: conscious, creative manipulation of musical ideas; but also unconscious variation during music recall. It is the latter phenomenon that we wish to study: variation which occurs in oral transmission, in which a melody is taught without the help

  9. Studying Variation in Tunes

    NARCIS (Netherlands)

    Janssen, B.; van Kranenburg, P.

    2014-01-01

    Variation in music can be caused by different phenomena: conscious, creative manipulation of musical ideas; but also unconscious variation during music recall. It is the latter phenomenon that we wish to study: variation which occurs in oral transmission, in which a melody is taught without the help

  10. 49 CFR 231.20 - Variation in size permitted.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Variation in size permitted. 231.20 Section 231.20..., DEPARTMENT OF TRANSPORTATION RAILROAD SAFETY APPLIANCE STANDARDS § 231.20 Variation in size permitted. To... total variation of 5 percent below size given is permitted....

  11. TQM - Total Quality Management (Bibliography)

    Science.gov (United States)

    1990-05-01

    TOTAL QUALITY MANAGEMENT (BIBLIOORAPHY) PREPARED BY... Total Quality Management (TQM), it is an appropriate time to provide an overview of the literature available on the topic. The Total Quality Management bibliography...Secretary 32 CFR Part 281 Total Quality Management Agency: Office of the Secretary, DOD Action: Proposed rule Summary: This proposed rule establishes

  12. Variational Integrators for Reduced Magnetohydrodynamics

    CERN Document Server

    Kraus, Michael; Grasso, Daniela

    2015-01-01

    Reduced magnetohydrodynamics is a simplified set of magnetohydrodynamics equations with applications to both fusion and astrophysical plasmas, possessing a noncanonical Hamiltonian structure and consequently a number of conserved functionals. We propose a new discretisation strategy for these equations based on a discrete variational principle applied to a formal Lagrangian. The resulting integrator preserves important quantities like the total energy, magnetic helicity and cross helicity exactly (up to machine precision). As the integrator is free of numerical resistivity, spurious reconnection along current sheets is absent in the ideal case. If effects of electron inertia are added, reconnection of magnetic field lines is allowed, although the resulting model still possesses a noncanonical Hamiltonian structure. After reviewing the conservation laws of the model equations, the adopted variational principle with the related conservation laws are described both at the continuous and discrete level. We verify...

  13. Rotational total skin and total nodal radiotherapy in mycosis fungoides

    Energy Technology Data Exchange (ETDEWEB)

    Bamberg, M.; Molls, M.; Langrock, J.; Muskalla, K.; Quast, U.

    1987-04-01

    The following report describes our technique of rotational total skin radiotherapy with electrons (TSER). We present stage related treatment results. Furthermore our first experiences with the combination of TSER and total nodal irradiation (TNI) are communicated.

  14. Variation of fundamental constants

    CERN Document Server

    Flambaum, V V

    2006-01-01

    We present a review of recent works devoted to the variation of the fine structure constant alpha, strong interaction and fundamental masses. There are some hints for the variation in quasar absorption spectra, Big Bang nucleosynthesis, and Oklo natural nuclear reactor data. A very promising method to search for the variation of the fundamental constants consists in comparison of different atomic clocks. Huge enhancement of the variation effects happens in transition between accidentally degenerate atomic and molecular energy levels. A new idea is to build a ``nuclear'' clock based on the ultraviolet transition between very low excited state and ground state in Thorium nucleus. This may allow to improve sensitivity to the variation up to 10 orders of magnitude! Huge enhancement of the variation effects is also possible in cold atomic and molecular collisions near Feschbach resonance.

  15. Calculus of variations

    CERN Document Server

    Gelfand, I M

    2000-01-01

    Based on a series of lectures given by I. M. Gelfand at Moscow State University, this book actually goes considerably beyond the material presented in the lectures. The aim is to give a treatment of the elements of the calculus of variations in a form both easily understandable and sufficiently modern. Considerable attention is devoted to physical applications of variational methods, e.g., canonical equations, variational principles of mechanics, and conservation laws.The reader who merely wishes to become familiar with the most basic concepts and methods of the calculus of variations need on

  16. Error analysis of flux limiter schemes at extrema

    Science.gov (United States)

    Kriel, A. J.

    2017-01-01

    Total variation diminishing (TVD) schemes have been an invaluable tool for the solution of hyperbolic conservation laws. One of the major shortcomings of commonly used TVD methods is the loss of accuracy near extrema. Although large amounts of anti-diffusion usually benefit the resolution of discontinuities, a balanced limiter such as Van Leer's performs better at extrema. Reliable criteria, however, for the performance of a limiter near extrema are not readily apparent. This work provides theoretical quantitative estimates for the local truncation errors of flux limiter schemes at extrema for a uniform grid. Moreover, the component of the error attributed to the flux limiter was obtained. This component is independent of the problem and grid spacing, and may be considered a property of the limiter that reflects the performance at extrema. Numerical test problems validate the results.

  17. An unusual case of total ophthalmoplegia

    Directory of Open Access Journals (Sweden)

    Chowdhury Ravindra

    2009-01-01

    Full Text Available An eight-year-old male child presented with drooping of the left eyelid with a history of penetrating injury of hard palate by an iron spoon seven days ago, which had already been removed by the neurosurgeon as the computed tomography scan revealed a spoon in the left posterior ethmoid and sphenoid bone penetrating into the middle cranial fossa. On examination, visual acuity was 20/20 in each eye and left eye showed total ophthalmoplegia. Oral cavity revealed a hole in the left lateral part of the hard palate. We managed the case with tapering dose of systemic prednisolone. The total ophthalmoplegia was markedly improved in one month. Cases of foreign bodies in the orbit with intracranial extension are not unusual, but the path this foreign body traveled through the hard palate without affecting the optic nerve, internal carotid artery or cavernous sinus makes an interesting variation.

  18. Total body irradiation: current indications; L`irradiation corporelle totale: les indications actuelles

    Energy Technology Data Exchange (ETDEWEB)

    Giraud, P.; Danhier, S.; Dubray, B.; Cosset, J.M. [Institut Curie, 75 - Paris (France)

    1998-05-01

    The choice of dose and fractionation for total body irradiation is made difficult by the large number of considerations to be taken into account. The outcome of bone marrow transplantation after total body irradiation can be understood in terms of tumor cell killing, engraftment, and normal tissue damage, each of these endpoints being influenced by irradiation-, disease-, transplant-, and patient- related factors. Interpretation of clinical data is further hampered by the overwhelming influence of logistic constraints, the small numbers of randomized studies, and the concomitant variations in total dose and fraction size or dose rate. So far, three cautious conclusions can be drawn in order to tentatively adapt the total body irradiation schedule to clinically-relevant situations. Firstly, the organs at risk for normal tissue damage (lung, liver, lens, kidney) are protected by delivering small doses per fraction at low dose rate. This suggests that, when toxicity is at stake (e.g. in children), fractionated irradiation should be preferred, provided that inter-fraction intervals are long enough. Secondly, fractionated irradiation should be avoided in case of T-cell depleted transplant, given the high risk of graft rejection in this setting. An alternative would be to increase total (or fractional) dose of fractionated total body irradiation, but this approach is likely to induce more normal tissue toxicity. Thirdly, clinical data have shown higher relapse rates in chronic myeloid leukemia after fractionated or low dose rate total body irradiation, suggesting that fractionated irradiation should not be recommended, unless total (or fractional) dose is increased. Total body irradiation-containing regimens, primarily cyclophosphamide / total body irradiation, are either equivalent to or better than the chemotherapy-only regimens, primarily busulfan / cyclophosphamide. Busulfan / cyclophosphamide certainly represents a reasonable alternative, especially in patients who

  19. Total Restrained Bondage in Graphs

    Institute of Scientific and Technical Information of China (English)

    Nader JAFARI RAD; Roslan HASNI; Joanna RACZEK; Lutz VOLKMANN

    2013-01-01

    A subset S of vertices of a graph G with no isolated vertex is a total restrained dominating set if every vertex is adjacent to a vertex in S and every vertex in V(G)-S is also adjacent to a vertex in V(G)-S.The total restrained domination number of G is the minimum cardinality of a total restrained dominating set of G.In this paper we initiate the study of total restrained bondage in graphs.The total restrained bondage number in a graph G with no isolated vertex,is the minimum cardinality of a subset of edges E such that G-E has no isolated vertex and the total restrained domination number of G-E is greater than the total restrained domination number of G.We obtain several properties,exact values and bounds for the total restrained bondage number of a graph.

  20. Ladder Variational Autoencoder

    DEFF Research Database (Denmark)

    Sønderby, Casper Kaae; Raiko, Tapani; Maaløe, Lars

    2016-01-01

    Variational autoencoders are powerful models for unsupervised learning. However deep models with several layers of dependent stochastic variables are difficult to train which limits the improvements obtained using these highly expressive models. We propose a new inference model, the Ladder Variat...

  1. Variation of Fundamental Constants

    Science.gov (United States)

    Flambaum, V. V.

    2006-11-01

    Theories unifying gravity with other interactions suggest temporal and spatial variation of the fundamental ``constants'' in expanding Universe. The spatial variation can explain a fine tuning of the fundamental constants which allows humans (and any life) to appear. We appeared in the area of the Universe where the values of the fundamental constants are consistent with our existence. We present a review of recent works devoted to the variation of the fine structure constant α, strong interaction and fundamental masses. There are some hints for the variation in quasar absorption spectra. Big Bang nucleosynthesis, and Oklo natural nuclear reactor data. A very promising method to search for the variation of the fundamental constants consists in comparison of different atomic clocks. Huge enhancement of the variation effects happens in transition between accidentally degenerate atomic and molecular energy levels. A new idea is to build a ``nuclear'' clock based on the ultraviolet transition between very low excited state and ground state in Thorium nucleus. This may allow to improve sensitivity to the variation up to 10 orders of magnitude! Huge enhancement of the variation effects is also possible in cold atomic and molecular collisions near Feshbach resonance.

  2. Genetic variation in variability

    NARCIS (Netherlands)

    Mulder, Herman; Gienapp, Phillip; Visser, Marcel E.

    2016-01-01

    Variation in traits is essential for natural selection to operate and genetic and environmental effects can contribute to this phenotypic variation. From domesticated populations, we know that families can differ in their level of within-family variance, which leads to the intriguing situation th

  3. Physiology of biological variation

    NARCIS (Netherlands)

    Schouten, R.E.

    2004-01-01

    In agricultural products, variation exists in quality attributes between batches. Examples of this biological variation are well known and the general response is trying to suppress it as much as possible; to create uniformity using pre- andpostharvestmethods. This thesis

  4. Weak Total Resolvability In Graphs

    Directory of Open Access Journals (Sweden)

    Casel Katrin

    2016-02-01

    Full Text Available A vertex v ∈ V (G is said to distinguish two vertices x, y ∈ V (G of a graph G if the distance from v to x is di erent from the distance from v to y. A set W ⊆ V (G is a total resolving set for a graph G if for every pair of vertices x, y ∈ V (G, there exists some vertex w ∈ W − {x, y} which distinguishes x and y, while W is a weak total resolving set if for every x ∈ V (G−W and y ∈ W, there exists some w ∈ W −{y} which distinguishes x and y. A weak total resolving set of minimum cardinality is called a weak total metric basis of G and its cardinality the weak total metric dimension of G. Our main contributions are the following ones: (a Graphs with small and large weak total metric bases are characterised. (b We explore the (tight relation to independent 2-domination. (c We introduce a new graph parameter, called weak total adjacency dimension and present results that are analogous to those presented for weak total dimension. (d For trees, we derive a characterisation of the weak total (adjacency metric dimension. Also, exact figures for our parameters are presented for (generalised fans and wheels. (e We show that for Cartesian product graphs, the weak total (adjacency metric dimension is usually pretty small. (f The weak total (adjacency dimension is studied for lexicographic products of graphs.

  5. Variational integrators for reduced magnetohydrodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Kraus, Michael, E-mail: michael.kraus@ipp.mpg.de [Max-Planck-Institut für Plasmaphysik, Boltzmannstraße 2, 85748 Garching (Germany); Technische Universität München, Zentrum Mathematik, Boltzmannstraße 3, 85748 Garching (Germany); Tassi, Emanuele, E-mail: tassi@cpt.univ-mrs.fr [Aix-Marseille Université, Université de Toulon, CNRS, CPT, UMR 7332, 163 avenue de Luminy, case 907, 13288 cedex 9 Marseille (France); Grasso, Daniela, E-mail: daniela.grasso@infm.polito.it [ISC-CNR and Politecnico di Torino, Dipartimento Energia, C.so Duca degli Abruzzi 24, 10129 Torino (Italy)

    2016-09-15

    Reduced magnetohydrodynamics is a simplified set of magnetohydrodynamics equations with applications to both fusion and astrophysical plasmas, possessing a noncanonical Hamiltonian structure and consequently a number of conserved functionals. We propose a new discretisation strategy for these equations based on a discrete variational principle applied to a formal Lagrangian. The resulting integrator preserves important quantities like the total energy, magnetic helicity and cross helicity exactly (up to machine precision). As the integrator is free of numerical resistivity, spurious reconnection along current sheets is absent in the ideal case. If effects of electron inertia are added, reconnection of magnetic field lines is allowed, although the resulting model still possesses a noncanonical Hamiltonian structure. After reviewing the conservation laws of the model equations, the adopted variational principle with the related conservation laws is described both at the continuous and discrete level. We verify the favourable properties of the variational integrator in particular with respect to the preservation of the invariants of the models under consideration and compare with results from the literature and those of a pseudo-spectral code.

  6. Variational integrators for reduced magnetohydrodynamics

    Science.gov (United States)

    Kraus, Michael; Tassi, Emanuele; Grasso, Daniela

    2016-09-01

    Reduced magnetohydrodynamics is a simplified set of magnetohydrodynamics equations with applications to both fusion and astrophysical plasmas, possessing a noncanonical Hamiltonian structure and consequently a number of conserved functionals. We propose a new discretisation strategy for these equations based on a discrete variational principle applied to a formal Lagrangian. The resulting integrator preserves important quantities like the total energy, magnetic helicity and cross helicity exactly (up to machine precision). As the integrator is free of numerical resistivity, spurious reconnection along current sheets is absent in the ideal case. If effects of electron inertia are added, reconnection of magnetic field lines is allowed, although the resulting model still possesses a noncanonical Hamiltonian structure. After reviewing the conservation laws of the model equations, the adopted variational principle with the related conservation laws is described both at the continuous and discrete level. We verify the favourable properties of the variational integrator in particular with respect to the preservation of the invariants of the models under consideration and compare with results from the literature and those of a pseudo-spectral code.

  7. Ensembl variation resources

    Directory of Open Access Journals (Sweden)

    Marin-Garcia Pablo

    2010-05-01

    Full Text Available Abstract Background The maturing field of genomics is rapidly increasing the number of sequenced genomes and producing more information from those previously sequenced. Much of this additional information is variation data derived from sampling multiple individuals of a given species with the goal of discovering new variants and characterising the population frequencies of the variants that are already known. These data have immense value for many studies, including those designed to understand evolution and connect genotype to phenotype. Maximising the utility of the data requires that it be stored in an accessible manner that facilitates the integration of variation data with other genome resources such as gene annotation and comparative genomics. Description The Ensembl project provides comprehensive and integrated variation resources for a wide variety of chordate genomes. This paper provides a detailed description of the sources of data and the methods for creating the Ensembl variation databases. It also explores the utility of the information by explaining the range of query options available, from using interactive web displays, to online data mining tools and connecting directly to the data servers programmatically. It gives a good overview of the variation resources and future plans for expanding the variation data within Ensembl. Conclusions Variation data is an important key to understanding the functional and phenotypic differences between individuals. The development of new sequencing and genotyping technologies is greatly increasing the amount of variation data known for almost all genomes. The Ensembl variation resources are integrated into the Ensembl genome browser and provide a comprehensive way to access this data in the context of a widely used genome bioinformatics system. All Ensembl data is freely available at http://www.ensembl.org and from the public MySQL database server at ensembldb.ensembl.org.

  8. Variational Transition State Theory

    Energy Technology Data Exchange (ETDEWEB)

    Truhlar, Donald G. [Univ. of Minnesota, Minneapolis, MN (United States)

    2016-09-29

    This is the final report on a project involving the development and applications of variational transition state theory. This project involved the development of variational transition state theory for gas-phase reactions, including optimized multidimensional tunneling contributions and the application of this theory to gas-phase reactions with a special emphasis on developing reaction rate theory in directions that are important for applications to combustion. The development of variational transition state theory with optimized multidimensional tunneling as a useful computational tool for combustion kinetics involved eight objectives.

  9. Porosity variation in chalk

    DEFF Research Database (Denmark)

    Lind, Ida; Grøn, Peter

    1996-01-01

    Vertical porosity variations in chalk are generally assumed to result from either a vaguely defined combination of primary sedimentary and diagenetic processes or solely to diagenetic processes. In this study, image analysis of backscatter electron images of polished samples and geochemical...... microprobe mapping were applied to measure the porosity variation in a limited number of chalk samples. Microscope data indicate that in all cases the chalk has been subjected to diagenetic processes, but our data suggest that the variations in porosity originate in primary sedimentary differences....

  10. Total Quality Management (TQM) Bibliography

    Science.gov (United States)

    1990-04-01

    GTE FIE COPY DTIC c" ECTE 8JUL 25 1990u TOTAL QUALITY MANAGEMENT (TQM) BIBLIOGRAPHY APRIL-1990 Jointly supported by __’__________-_________ Jointly...Arsenal, AL 35898-5241 1I. TITLE (Include Security Classification) TOTAL QUALITY MANAGEMENT (TQM) BIBL IRAPHY APRIL-1990 12. PERSONAL AUTHOR(S) Knott...implementation of the concept of total quality management (TQM). The selected coverage includes books, periodical articles, conference papers and reports. Coded

  11. Solar gravitational energy and luminosity variations

    CERN Document Server

    Fazel, Z; Lefebvre, S; Ajabshirizadeh, A; Pireaux, S; 10.1016/j.newst.2007.05.003

    2009-01-01

    Due to non-homogeneous mass distribution and non-uniform velocity rate inside the Sun, the solar outer shape is distorted in latitude. In this paper, we analyze the consequences of a temporal change in this figure on the luminosity. To do so, we use the Total Solar Irradiance (TSI) as an indicator of luminosity. Considering that most of the authors have explained the largest part of the TSI modulation with magnetic network (spots and faculae) but not the whole, we could set constraints on radius and effective temperature variations (dR, dT). However computations show that the amplitude of solar irradiance modulation is very sensitive to photospheric temperature variations. In order to understand discrepancies between our best fit and recent observations of Livingston et al. (2005), showing no effective surface temperature variation during the solar cycle, we investigated small effective temperature variation in irradiance modeling. We emphasized a phase-shift (correlated or anticorrelated radius and irradianc...

  12. Saturn chorus latitudinal variations

    National Research Council Canada - National Science Library

    Menietti, J. D; Hospodarsky, G. B; Shprits, Y. Y; Gurnett, D. A

    2014-01-01

    The variation of propagation properties of whistler mode chorus as a function of latitude is not well known at Saturn but is important for the calculation of pitch angle diffusion and nonlinear growth of chorus...

  13. Variation within categories.

    NARCIS (Netherlands)

    Das-Smaal, E.A.; Swart, de J.H.

    1984-01-01

    Two aspects of variation within categories, relating to different models of categorization, were investigated - frequency of dimensional values and typicality differences within values. The influence of range of typicality experienced during learning and of informational value of feedback was also

  14. Variational principles in physics

    CERN Document Server

    Basdevant, Jean-Louis

    2007-01-01

    Optimization under constraints is an essential part of everyday life. Indeed, we routinely solve problems by striking a balance between contradictory interests, individual desires and material contingencies. This notion of equilibrium was dear to thinkers of the enlightenment, as illustrated by Montesquieu’s famous formulation: "In all magistracies, the greatness of the power must be compensated by the brevity of the duration." Astonishingly, natural laws are guided by a similar principle. Variational principles have proven to be surprisingly fertile. For example, Fermat used variational methods to demonstrate that light follows the fastest route from one point to another, an idea which came to be known as Fermat’s principle, a cornerstone of geometrical optics. Variational Principles in Physics explains variational principles and charts their use throughout modern physics. The heart of the book is devoted to the analytical mechanics of Lagrange and Hamilton, the basic tools of any physicist. Prof. Basdev...

  15. The Schwinger Variational Method

    Science.gov (United States)

    Huo, Winifred M.

    1995-01-01

    Variational methods have proven invaluable in theoretical physics and chemistry, both for bound state problems and for the study of collision phenomena. For collisional problems they can be grouped into two types: those based on the Schroedinger equation and those based on the Lippmann-Schwinger equation. The application of the Schwinger variational (SV) method to e-molecule collisions and photoionization has been reviewed previously. The present chapter discusses the implementation of the SV method as applied to e-molecule collisions.

  16. Generalized quasi variational inequalities

    Energy Technology Data Exchange (ETDEWEB)

    Noor, M.A. [King Saud Univ., Riyadh (Saudi Arabia)

    1996-12-31

    In this paper, we establish the equivalence between the generalized quasi variational inequalities and the generalized implicit Wiener-Hopf equations using essentially the projection technique. This equivalence is used to suggest and analyze a number of new iterative algorithms for solving generalized quasi variational inequalities and the related complementarity problems. The convergence criteria is also considered. The results proved in this paper represent a significant improvement and refinement of the previously known results.

  17. Total Synthesis of Bryostatin 9

    OpenAIRE

    Wender, Paul A.; Schrier, Adam J.

    2011-01-01

    The total synthesis of bryostatin 9 was accomplished using a uniquely step economical and convergent Prins-driven macrocyclization strategy. At 25 linear and 42 total steps, this is currently the most concise and convergent (5 steps post fragment coupling) synthesis of a potent bryostatin.

  18. Total synthesis of bryostatin 9.

    Science.gov (United States)

    Wender, Paul A; Schrier, Adam J

    2011-06-22

    The total synthesis of bryostatin 9 was accomplished using a uniquely step-economical and convergent Prins-driven macrocyclization strategy. At 25 linear and 42 total steps, this is currently the most concise and convergent synthesis of a potent bryostatin.

  19. The total charm cross section

    Energy Technology Data Exchange (ETDEWEB)

    Vogt, R

    2007-09-14

    We assess the theoretical uncertainties on the total charm cross section. We discuss the importance of the quark mass, the scale choice and the parton densities on the estimate of the uncertainty. We conclude that the uncertainty on the total charm cross section is difficult to quantify.

  20. Total parenteral nutrition in children.

    Science.gov (United States)

    Zlotkin, S H; Stallings, V A; Pencharz, P B

    1985-04-01

    This article first focuses on the indications for total parenteral nutrition and the effect of its use on the outcome of various nutrient-depleting diseases in infants and children. This is followed by a discussion of some of the newer nutrient additions to total parenteral nutrition regimens, such as biotin, carnitine, zinc, copper, iron, and others.

  1. Variation in Metaphor Variation in Metaphor

    Directory of Open Access Journals (Sweden)

    Zóltan Kövecses

    2010-05-01

    Full Text Available

    Cognitive linguists have so far paid a great deal of attention to the emarkable universality of many conceptual metaphors. However, their theories fail to account for the equally impressive diversity of metaphorical conceptualization both across and within cultures. The present paper is an attempt to lay down the foundations of a theory of metaphor that is capable of simultaneously accounting for both universality and variation in metaphor.

     

    Cognitive linguists have so far paid a great deal of attention to the emarkable universality of many conceptual metaphors. However, their theories fail to account for the equally impressive diversity of metaphorical conceptualization both across and within cultures. The present paper is an attempt to lay down the foundations of a theory of metaphor that is capable of simultaneously accounting for both universality and variation in metaphor.

  2. Fractionation and determination of total antioxidant capacity, total ...

    African Journals Online (AJOL)

    DEYAKS PLC

    2014-01-29

    Jan 29, 2014 ... components that can scavenge reactive oxygen species. In this study, the total ... Medicinal plants containing active chemical constituents with high antioxidant property play an important role in the prevention of various ...

  3. Assessing Educational Processes Using Total-Quality-Management Measurement Tools.

    Science.gov (United States)

    Macchia, Peter, Jr.

    1993-01-01

    Discussion of the use of Total Quality Management (TQM) assessment tools in educational settings highlights and gives examples of fishbone diagrams, or cause and effect charts; Pareto diagrams; control charts; histograms and check sheets; scatter diagrams; and flowcharts. Variation and quality are discussed in terms of continuous process…

  4. Totality eclipses of the Sun

    CERN Document Server

    Littmann, Mark; Willcox, Ken

    2008-01-01

    A total eclipse of the Sun is the most awesome sight in the heavens. Totality: Eclipses of the Sun takes you to eclipses of the past, present, and future, and lets you see - and feel - why people travel to the ends of the Earth to observe them. - ;A total eclipse of the Sun is the most awesome sight in the heavens. Totality: Eclipses of the Sun takes you to eclipses of the past, present, and future, and lets you see - and feel - why people travel to the ends of the Earth to observe them. Totality: Eclipses of the Sun is the best guide and reference book on solar eclipses ever written. It explains: how to observe them; how to photograph and videotape them; why they occur; their history and mythology; and future eclipses - when and where to see them. Totality also tells the remarkable story of how eclipses shocked scientists, revealed the workings of the Sun, and made Einstein famous. And the book shares the experiences and advice of many veteran eclipse observers. Totality: Eclipses of the Sun is profusely ill...

  5. Total quality management issues in managed care.

    Science.gov (United States)

    McLaughlin, C P; Kaluzny, A D

    1997-01-01

    The implementation of total quality management (TQM) in health care has gone on in parallel with the growth of managed care. What is the interaction between the two? Key issues are the ascendance of cost control over quality in many areas, erosion of employee commitment and loyalty, and a short-run orientation. Associated with this is an emphasis on organizational learning rather than learning by autonomous professionals. Both TQM and managed care acknowledge the dynamic nature of clinical processes and the ability and responsibility of both institutions and clinicians to improve their processes. Both are consistent with efforts to identify and implement best practices. However, these similarities should not mask fundamental differences. Continuous improvement must shift its focus from avoiding unnecessary variation to facilitating rapid organizational learning and institutionalizing mass customization into the delivery of health services.

  6. Structural variations in pig genomes

    NARCIS (Netherlands)

    Paudel, Y.

    2015-01-01

    Abstract Paudel, Y. (2015). Structural variations in pig genomes. PhD thesis, Wageningen University, the Netherlands Structural variations are chromosomal rearrangements such as insertions-deletions (INDELs), duplications, inversions, translocations, and copy number variations (CNVs

  7. On the link between martian total ozone and potential vorticity

    Science.gov (United States)

    Holmes, James A.; Lewis, Stephen R.; Patel, Manish R.

    2017-01-01

    We demonstrate for the first time that total ozone in the martian atmosphere is highly correlated with the dynamical tracer, potential vorticity, under certain conditions. The degree of correlation is investigated using a Mars global circulation model including a photochemical model. Potential vorticity is the quantity of choice to explore the dynamical nature of polar vortices because it contains information on winds and temperature in a single scalar variable. The correlation is found to display a distinct seasonal variation, with a strong positive correlation in both northern and southern winter at poleward latitudes in the northern and southern hemisphere respectively. The identified strong correlation implies variations in polar total ozone during winter are predominantly controlled by dynamical processes in these spatio-temporal regions. The weak correlation in northern and southern summer is due to the dominance of photochemical reactions resulting from extended exposure to sunlight. The total ozone/potential vorticity correlation is slightly weaker in southern winter due to topographical variations and the preference for ozone to accumulate in Hellas basin. In northern winter, total ozone can be used to track the polar vortex edge. The ozone/potential vorticity ratio is calculated for both northern and southern winter on Mars for the first time. Using the strong correlation in total ozone and potential vorticity in northern winter inside the polar vortex, it is shown that potential vorticity can be used as a proxy to deduce the distribution of total ozone where satellites cannot observe for the majority of northern winter. Where total ozone observations are available on the fringes of northern winter at poleward latitudes, the strong relationship of total ozone and potential vorticity implies that total ozone anomalies in the surf zone of the northern polar vortex can potentially be used to determine the origin of potential vorticity filaments.

  8. Qualità totale e mobilità totale

    Directory of Open Access Journals (Sweden)

    Giuseppe Trieste

    2010-04-01

    Full Text Available FIABA ONLUS (Italian Fund for Elimination of Architectural Barriers was founded in 2000 with the aim of promoting a culture of equal opportunities and, above all, it has as its main goal to involve public and private institutions to create a really accessible and usable environment for everyone. Total accessibility, Total usability and Total mobility are key indicators to define quality of life within cities. A supportive environment that is free of architectural, cultural and psychological barriers allows everyone to live with ease and universality. In fact, people who access to goods and services in the urban context can use to their advantage time and space, so they can do their activities and can maintain relationships that are deemed significant for their social life. The main aim of urban accessibility is to raise the comfort of space for citizens, eliminating all barriers that discriminate people, and prevent from an equality of opportunity. “FIABA FUND - City of ... for the removal of architectural barriers” is an idea of FIABA that has already affected many regions of Italy as Lazio, Lombardy, Campania, Abruzzi and Calabria. It is a National project which provides for opening a bank account in the cities of referring, in which for the first time, all together, individuals and private and public institutions can make a donation to fund initiatives for the removal of architectural barriers within its own territory for a real and effective total accessibility. Last February the fund was launched in Rome with the aim of achieving a Capital without barriers and a Town European model of accessibility and usability. Urban mobility is a prerequisite to access to goods and services, and to organize activities related to daily life. FIABA promotes the concept of sustainable mobility for all, supported by the European Commission’s White Paper. We need a cultural change in management and organization of public means, which might focus on

  9. Total Product Life Cycle (TPLC)

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Total Product Life Cycle (TPLC) database integrates premarket and postmarket data about medical devices. It includes information pulled from CDRH databases...

  10. Total Product Life Cycle (TPLC)

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Total Product Life Cycle (TPLC) database integrates premarket and postmarket data about medical devices. It includes information pulled from CDRH databases...

  11. Total eclipses of the sun.

    Science.gov (United States)

    Zirker, J B

    1980-12-19

    Total eclipses of the sun offer research opportunities in a variety of sciences. Some of the advances in solar physics resulting from eclipse observations are discussed. Experiments at the total eclipse of 16 February 1980 in India are also described. These included a test of general relativity, studies in coronal physics, investigations of solar prominences, diameter measurements, a search for interplanetary dust, a study of the gravity waves in the earth's atmosphere, and experiments on the biological effects on animals and humans.

  12. Total Quality Management Implementation Plan.

    Science.gov (United States)

    1989-06-01

    E 14. SUBJECT TERMS 15. NUMBER OF PAGES TOM ( Total Quality Management ), Continuous Process Improvement,_________ Depot Operations, Supply Support 16... Quality Management Implementation Plan 6. AUTHOR(S) 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION Defense General...Reduction PrOtect (O704.Ot8SL Wasilngton, OC 20503j. .EPORT DATE 3. REPORT TYPE AND DATES COVERED June 19891 4. TITLE AND SUBTITLE S. FUNDING NUMBERS Total

  13. The total synthesis of psymberin.

    Science.gov (United States)

    Huang, Xianhai; Shao, Ning; Palani, Anandan; Aslanian, Robert; Buevich, Alexei

    2007-06-21

    The total synthesis of a new member of the pederin family of natural products, psymberin 1, was accomplished. Using a recently reported novel and efficient PhI(OAc)2 mediated oxidative entry to 2-(N-acylaminal)-substituted tetrahydropyrans as the key step, this total synthesis was executed in a convergent and efficient manner. The longest linear sequence of this synthesis was 22 steps starting from known 6.

  14. Total Quality From The Top

    Science.gov (United States)

    1993-04-01

    product followed. But, according to V. Daniel Hunt, author of Quality in America, "the time bomb ticks silently 1 V. Daniel Hunt. Quality in America...Michael L., Richard K. Lester, and Robert M. Solow . Made In America. Cambridge, MA:MIT Press, 1989. Doyle, Kevin. "Who’s Killing Total Quality?" Incentive...Gatanas, Harry. Lt Col, USA. "Leadership and Total Quality Management." Carlisle Barracks, PA:U.S. Army War College. April 1992. Hunt, V. Daniel

  15. Discrete Variational Optimal Control

    CERN Document Server

    Jimenez, Fernando; de Diego, David Martin

    2012-01-01

    This paper develops numerical methods for optimal control of mechanical systems in the Lagrangian setting. It extends the theory of discrete mechanics to enable the solutions of optimal control problems through the discretization of variational principles. The key point is to solve the optimal control problem as a variational integrator of a specially constructed higher-dimensional system. The developed framework applies to systems on tangent bundles, Lie groups, underactuated and nonholonomic systems with symmetries, and can approximate either smooth or discontinuous control inputs. The resulting methods inherit the preservation properties of variational integrators and result in numerically robust and easily implementable algorithms. Several theoretical and a practical examples, e.g. the control of an underwater vehicle, will illustrate the application of the proposed approach.

  16. Discrete Variational Optimal Control

    Science.gov (United States)

    Jiménez, Fernando; Kobilarov, Marin; Martín de Diego, David

    2013-06-01

    This paper develops numerical methods for optimal control of mechanical systems in the Lagrangian setting. It extends the theory of discrete mechanics to enable the solutions of optimal control problems through the discretization of variational principles. The key point is to solve the optimal control problem as a variational integrator of a specially constructed higher dimensional system. The developed framework applies to systems on tangent bundles, Lie groups, and underactuated and nonholonomic systems with symmetries, and can approximate either smooth or discontinuous control inputs. The resulting methods inherit the preservation properties of variational integrators and result in numerically robust and easily implementable algorithms. Several theoretical examples and a practical one, the control of an underwater vehicle, illustrate the application of the proposed approach.

  17. Variation and Synthetic Speech

    CERN Document Server

    Miller, C; Massey, N; Miller, Corey; Karaali, Orhan; Massey, Noel

    1997-01-01

    We describe the approach to linguistic variation taken by the Motorola speech synthesizer. A pan-dialectal pronunciation dictionary is described, which serves as the training data for a neural network based letter-to-sound converter. Subsequent to dictionary retrieval or letter-to-sound generation, pronunciations are submitted a neural network based postlexical module. The postlexical module has been trained on aligned dictionary pronunciations and hand-labeled narrow phonetic transcriptions. This architecture permits the learning of individual postlexical variation, and can be retrained for each speaker whose voice is being modeled for synthesis. Learning variation in this way can result in greater naturalness for the synthetic speech that is produced by the system.

  18. Variational electrodynamics of Atoms

    CERN Document Server

    De Luca, Jayme

    2013-01-01

    We study extrema with velocity discontinuities for the variational electromagnetic two-body problem. Along $C^2$ segments, these broken extrema satisfy the Euler-Lagrange equations of the variational principle, which are neutral differential delay equations with state-dependent deviating arguments. At points where accelerations are not defined and velocities are discontinuous, broken extrema satisfy Weierstrass-Erdmann corner conditions that energies and momenta are continuous. Here we construct periodic broken extrema near the $C^{\\infty}$ two-body circular orbits, using piecewise-defined $C^2$ solutions of the neutral differential delay equations along regular segments and a variational approximation for the boundary-layer segments. Broken periodic extrema with an integer number of corner points bifurcate from a discrete set of circular orbits, with scales defined by the Weierstrass-Erdmann corner conditions. We consider the three cases of hydrogen, muonium and positronium atoms. In each case the broken ext...

  19. Fimbrial phase variation

    DEFF Research Database (Denmark)

    Khandige, Surabhi; Møller-Jensen, Jakob

    2016-01-01

    Surface fimbriae of pathogenic Escherichia coli facilitate sensing, adhesion and even invasion of host epithelial cells. While it is known that the pathogen has the potential to express a plethora of fimbrial variants susceptible to rapid phase ON/OFF variation, it is an open question if the fimb......Surface fimbriae of pathogenic Escherichia coli facilitate sensing, adhesion and even invasion of host epithelial cells. While it is known that the pathogen has the potential to express a plethora of fimbrial variants susceptible to rapid phase ON/OFF variation, it is an open question...... if the fimbrial diversity seen at the population level is the product of random stochasticity or a concerted effort based on active communication. Here we discuss the possibility of a mechanism alternative to a stochastic fimbrial phase variation model affecting the dynamics of a heterogeneous population....

  20. Total hip and total knee replacement: preoperative nursing management.

    Science.gov (United States)

    Lucas, Brian

    Total hip replacement (THR) and total knee replacement (TKR) surgery are carried out for the relief of hip or knee pain, usually caused by osteoarthritis. This is the first of two articles on THR and TKR. It will outline the different types of replacement used in lower limb joint replacement surgery. Preparation of patients for surgery requires attention to physical, psychological and social factors and these are explored in detail. The organization of services along the patient pathway to ensure comprehensive preparation is considered and the nursing role highlighted. The second article, to be published in the next issue, will discuss recovery and rehabilitation from THR and TKR surgery.

  1. Variational formulas of higher order mean curvatures

    CERN Document Server

    Xu, Ling

    2011-01-01

    In this paper, we establish the first variational formula and its Euler-Lagrange equation for the total $2p$-th mean curvature functional $\\mathcal {M}_{2p}$ of a submanifold $M^n$ in a general Riemannian manifold $N^{n+m}$ for $p=0,1,...,[\\frac{n}{2}]$. As an example, we prove that closed complex submanifolds in complex projective spaces are critical points of the functional $\\mathcal {M}_{2p}$, called relatively $2p$-minimal submanifolds, for all $p$. At last, we discuss the relations between relatively $2p$-minimal submanifolds and austere submanifolds in real space forms, as well as a special variational problem.

  2. Splines and variational methods

    CERN Document Server

    Prenter, P M

    2008-01-01

    One of the clearest available introductions to variational methods, this text requires only a minimal background in calculus and linear algebra. Its self-contained treatment explains the application of theoretic notions to the kinds of physical problems that engineers regularly encounter. The text's first half concerns approximation theoretic notions, exploring the theory and computation of one- and two-dimensional polynomial and other spline functions. Later chapters examine variational methods in the solution of operator equations, focusing on boundary value problems in one and two dimension

  3. Seasonal variation in pediatric dermatoses

    Directory of Open Access Journals (Sweden)

    Banerjee Sabyasachi

    2010-01-01

    Full Text Available Introduction: The under-five population is a unique and vulnerable component of our society that always demands special attention. Aims: Our present work aimed to study the seasonal variation, age-wise variation and distribution of lesions of common dermatoses of this age group. Materials and Methods: We clinically studied all fresh cases attending the skin OPD of our hospital for one month each from summer, rainy season and winter. Total number of patients was 879. Results: The top six skin diseases in our study were impetigo, miliaria, scabies, furunculosis, seborrheic dermatitis and papular urticaria. On statistical analysis, scabies and seborrheic dermatitis were more prevalent during winter while impetigo, furunculosis and miliaria were more during summer and rainy season. Papular urticaria was more frequent in the rainy season. Seborrheic dermatitis predominantly affected the infants while impetigo, furunculosis, miliaria and popular urticaria were commoner in older age groups. Conclusion: Distribution of lesions of common dermatoses will help diagnose difficult cases and extensive evaluation of the body parts which, by virtue of being commonly affected, are must-examine sites in under-five children.

  4. Work fluctuation and total entropy production in nonequilibrium processes

    Science.gov (United States)

    Funo, Ken; Shitara, Tomohiro; Ueda, Masahito

    2016-12-01

    Work fluctuation and total entropy production play crucial roles in small thermodynamic systems subject to large thermal fluctuations. We investigate a trade-off relation between them in a nonequilibrium situation in which a system starts from an arbitrary nonequilibrium state. We apply a variational method to study this problem and find a stationary solution against variations over protocols that describe the time dependence of the Hamiltonian of the system. Using the stationary solution, we find the minimum of the total entropy production for a given amount of work fluctuation. An explicit protocol that achieves this is constructed from an adiabatic process followed by a quasistatic process. The obtained results suggest how one can control the nonequilibrium dynamics of the system while suppressing its work fluctuation and total entropy production.

  5. The satellite total solar irradiance database

    Science.gov (United States)

    Willson, R. C.

    2009-12-01

    A precise knowledge of the total solar irradiance (TSI) over time is essential to understanding the physics of solar luminosity variation and its impact on the Earth in the form of climate change. A National Research Council study found that sustained trends as small as 0.25% per century were the most likely forcing for ‘little ice age’ climate minima during the 12th - 19th centuries. Recent phenomenological analyses of TSI observations and proxies indicate that TSI variation is an important climate change forcing on many timescales including the industrial era. The profound sociological and economic implications of understanding the relative climate change contributions of natural and anthropogenic forcings makes it essential that the satellite TSI database be precisely sustained into the foreseeable future. There are currently three satellite TSI monitoring experiments in operation: SOHO/VIRGO, ACRIMSAT/ACRIM3 and SORCE/TIM, in order of deployment (1996, 2000 and 2003, resp.). Results reported on their ‘native scales show the same basic variations in TSI over time, yet some smaller variations detected by ACRIM3 are less well defined or absent in the results of VIRGO and TIM. There is also a scale difference issue: TIM results are 0.35% lower than those of ACRIM3 and VIRGO, outside the ± 0.1% uncertainty bounds predicted for ACRIM3 and VIRGO, and well outside TIM’s ± 0.01% uncertainty design goal. TIM’s failure to achieve 0.01% uncertainty in flight demonstrates that the TSI monitoring paradigm shift of relying on measurement accuracy rather than a redundant/overlap strategy to provide long term traceability cannot be realized with current ‘ambient temperature’ technology. The only viable monitoring approach for the foreseeable future continues to be the redundant/overlap strategy that has provided the 31 year satellite TSI database to date with useful traceability. Intercomparisons of flight experiments at their levels of mutual precision can

  6. Total body water and total body potassium in anorexia nervosa

    Energy Technology Data Exchange (ETDEWEB)

    Dempsey, D.T.; Crosby, L.O.; Lusk, E.; Oberlander, J.L.; Pertschuk, M.J.; Mullen, J.L.

    1984-08-01

    In the ill hospitalized patient with clinically relevant malnutrition, there is a measurable decrease in the ratio of the total body potassium to total body water (TBK/TBW) and a detectable increase in the ratio of total exchangeable sodium to total exchangeable potassium (Nae/Ke). To evaluate body composition analyses in anorexia nervosa patients with chronic uncomplicated semistarvation, TBK and TBW were measured by whole body K40 counting and deuterium oxide dilution in 10 females with stable anorexia nervosa and 10 age-matched female controls. The ratio of TBK/TBW was significantly (p less than 0.05) higher in anorexia nervosa patients than controls. The close inverse correlation found in published studies between TBK/TBW and Nae/Ke together with our results suggest that in anorexia nervosa, Nae/Ke may be low or normal. A decreased TBK/TBW is not a good indicator of malnutrition in the anorexia nervosa patient. The use of a decreased TBK/TBW ratio or an elevated Nae/Ke ratio as a definition of malnutrition may result in inappropriate nutritional management in the patient with severe nonstressed chronic semistarvation.

  7. Total 2004 annual report; TOTAL 2004 rapport annuel

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-07-01

    This annual report of the Group Total brings information and economic data on the following topics, for the year 2004: the corporate governance, the corporate social responsibility, the shareholder notebook, the management report, the activities, the upstream (exploration and production) and downstream (refining and marketing) operating, chemicals and other matters. (A.L.B.)

  8. Seasonal Variation in Epidemiology

    Science.gov (United States)

    Marrero, Osvaldo

    2013-01-01

    Seasonality analyses are important in medical research. If the incidence of a disease shows a seasonal pattern, then an environmental factor must be considered in its etiology. We discuss a method for the simultaneous analysis of seasonal variation in multiple groups. The nuts and bolts are explained using simple trigonometry, an elementary…

  9. Variational transition state theory

    Energy Technology Data Exchange (ETDEWEB)

    Truhlar, D.G. [Univ. of Minnesota, Minneapolis (United States)

    1993-12-01

    This research program involves the development of variational transition state theory (VTST) and semiclassical tunneling methods for the calculation of gas-phase reaction rates and selected applications. The applications are selected for their fundamental interest and/or their relevance to combustion.

  10. Bounded variation and around

    CERN Document Server

    Appell, Jürgen; Merentes Díaz, Nelson José

    2013-01-01

    This monographis a self-contained exposition of the definition and properties of functionsof bounded variation and their various generalizations; the analytical properties of nonlinear composition operators in spaces of such functions; applications to Fourier analysis, nonlinear integral equations, and boundary value problems. The book is written for non-specialists. Every chapter closes with a list of exercises and open problems.

  11. Progress in variational methods

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ The International Conference on Variational Methods (ICVAM) was held from May 20th to 26th in 2007 at the Chern Institute of Mathematics, Nankai University, Tianjin, China. Twenty eight invited speakers from ten countries and areas worldwide gave their lectures at the conference.

  12. Variation and Linguistic Theory.

    Science.gov (United States)

    Bailey, Charles-James N.

    This volume presents principles and models for describing language variation, and introduces a time-based, dynamic framework for linguistic description. The book first summarizes some of the problems of grammatical description encountered from Saussure through the present and then outlines possibilities for new descriptions of language which take…

  13. Totally ossified metaplastic spinal meningioma.

    Science.gov (United States)

    Ju, Chang Il; Hida, Kazutoshi; Yamauchi, Tomohiro; Houkin, Kiyohiro

    2013-09-01

    A 61-year-old woman with a very rare case of totally ossified large thoracic spinal metaplastic meningioma, showing progressing myelopathy is presented. Computed tomographic images showed a large totally ossfied intradural round mass occupying the spinal canal on T9-10 level. Magnetic resonance imaging revealed a large T9-10 intradural extramedullary mass that was hypointense to spinal cord on T1- and T2-weighted sequences, partial enhancement was apparent after Gadolinium administration. The spinal cord was severely compressed and displaced toward the right at the level of T9-10. Surgical removal of the tumor was successfully accomplished via the posterior midline approach and the histological diagnosis verified an ossified metaplastic meningioma. The clinical neurological symptoms of patient were improved postoperatively. In this article we discuss the surgical and pathological aspects of rare case of spinal totally ossified metaplastic meningioma.

  14. An empirical model of the quiet daily geomagnetic field variation

    Science.gov (United States)

    Yamazaki, Y.; Yumoto, K.; Cardinal, M.G.; Fraser, B.J.; Hattori, P.; Kakinami, Y.; Liu, J.Y.; Lynn, K.J.W.; Marshall, R.; McNamara, D.; Nagatsuma, T.; Nikiforov, V.M.; Otadoy, R.E.; Ruhimat, M.; Shevtsov, B.M.; Shiokawa, K.; Abe, S.; Uozumi, T.; Yoshikawa, A.

    2011-01-01

    An empirical model of the quiet daily geomagnetic field variation has been constructed based on geomagnetic data obtained from 21 stations along the 210 Magnetic Meridian of the Circum-pan Pacific Magnetometer Network (CPMN) from 1996 to 2007. Using the least squares fitting method for geomagnetically quiet days (Kp ??? 2+), the quiet daily geomagnetic field variation at each station was described as a function of solar activity SA, day of year DOY, lunar age LA, and local time LT. After interpolation in latitude, the model can describe solar-activity dependence and seasonal dependence of solar quiet daily variations (S) and lunar quiet daily variations (L). We performed a spherical harmonic analysis (SHA) on these S and L variations to examine average characteristics of the equivalent external current systems. We found three particularly noteworthy results. First, the total current intensity of the S current system is largely controlled by solar activity while its focus position is not significantly affected by solar activity. Second, we found that seasonal variations of the S current intensity exhibit north-south asymmetry; the current intensity of the northern vortex shows a prominent annual variation while the southern vortex shows a clear semi-annual variation as well as annual variation. Thirdly, we found that the total intensity of the L current system changes depending on solar activity and season; seasonal variations of the L current intensity show an enhancement during the December solstice, independent of the level of solar activity. Copyright 2011 by the American Geophysical Union.

  15. Qualidade total e cultura organizacional

    OpenAIRE

    Machado, Denise Del Pra Netto

    1996-01-01

    Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Socio-Economico O ambiente dinâmico em que as organizações estão inseridas determina uma constante busca de competitividade. Com a adoção da Qualidade Total, como um processo ofensivo de enfrentamento das exigências de mercado, procura-se uma vantagem competitiva, além da sobrevi-vência organizacional. Com base no referencial teórico-empírico sobre Qualidade Total e Cultura Organizacional, procurou-se verifi-car o efei...

  16. Total Ozone Prediction: Stratospheric Dynamics

    Science.gov (United States)

    Jackman, Charles H.; Kawa, S. Ramdy; Douglass, Anne R.

    2003-01-01

    The correct prediction of total ozone as a function of latitude and season is extremely important for global models. This exercise tests the ability of a particular model to simulate ozone. The ozone production (P) and loss (L) will be specified from a well- established global model and will be used in all GCMs for subsequent prediction of ozone. This is the "B-3 Constrained Run" from M&MII. The exercise mostly tests a model stratospheric dynamics in the prediction of total ozone. The GCM predictions will be compared and contrasted with TOMS measurements.

  17. Stereoselective Total Synthesis of Mycalamides

    Institute of Scientific and Technical Information of China (English)

    Masahiro Toyota

    2005-01-01

    @@ 1Introduction Mycalamides A (1a) and B (1b) are potent antiviral compounds from a New Zealand sponge of the genus Mycale. Apart from their antitumor property, mycalamide A (1a) exhibits immunosuppressive action by blocking T-cell activation in mice and is significantly more potent than FK-506 and cyclosporine A. Because of their intriguing biological activity, unique structures and scarce supply of these natural products, mycalamides A (1a) and B (1b) have attracted considerable attention as target molecules for total synthesis, and total, formal, or partial syntheses of this family of compounds have been reported[1,2].

  18. VOICE REHABILITATION FOLLOWING TOTAL LARYNGECTOMY

    Directory of Open Access Journals (Sweden)

    Balasubramanian Thiagarajan

    2015-03-01

    Full Text Available Despite continuing advances in surgical management of laryngeal malignancy, total laryngectomy is still the treatment of choice in advanced laryngeal malignancies. Considering the longevity of the patient following total laryngectomy, various measures have been adopted in order to provide voice function to the patient. Significant advancements have taken place in voice rehabilitation of post laryngectomy patients. Advancements in oncological surgical techniques and irradiation techniques have literally cured laryngeal malignancies. Among the various voice rehabilitation techniques available TEP (Tracheo oesophageal puncture is considered to be the gold standard. This article attempts to explore the various voice rehabilitation technique available with primary focus on TEP.

  19. Advances in total scattering analysis

    Energy Technology Data Exchange (ETDEWEB)

    Proffen, Thomas E [Los Alamos National Laboratory; Kim, Hyunjeong [Los Alamos National Laboratory

    2008-01-01

    In recent years the analysis of the total scattering pattern has become an invaluable tool to study disordered crystalline and nanocrystalline materials. Traditional crystallographic structure determination is based on Bragg intensities and yields the long range average atomic structure. By including diffuse scattering into the analysis, the local and medium range atomic structure can be unravelled. Here we give an overview of recent experimental advances, using X-rays as well as neutron scattering as well as current trends in modelling of total scattering data.

  20. Sobredentadura total superior implantosoportada Superior total overdenture on implants

    Directory of Open Access Journals (Sweden)

    Luis Orlando Rodríguez García

    2010-06-01

    Full Text Available Se presenta un caso de un paciente desdentado total superior, rehabilitado en la consulta de implantología de la Clínica "Pedro Ortiz" del municipio Habana del Este en Ciudad de La Habana, Cuba, en el año 2009, mediante prótesis sobre implantes osteointegrados, técnica que se ha incorporado a la práctica estomatológica en Cuba como alternativa al tratamiento convencional en los pacientes desdentados totales. Se siguió un protocolo que comprendió una fase quirúrgica, procedimiento con o sin realización de colgajo y carga precoz o inmediata. Se presenta un paciente masculino de 56 años de edad, que acudió a la consulta multidisciplinaria, preocupado, porque se le habían elaborado tres prótesis en los últimos dos años y ninguna reunía los requisitos de retención que él necesitaba para sentirse seguro y cómodo con las mismas. El resultado final fue la satisfacción total del paciente, con el mejoramiento de la calidad estética y funcional.This is the case of a total maxilla edentulous patient seen in consultation of the "Pedro Ortíz" Clinic Implant of Habana del Este municipality in 2009 and con rehabilitation by prosthesis over osteointegration implants added to stomatology practice in Cuba as an alternative to conventional treatment in patients totally edentulous. We follow a protocol including a surgery or surgical phase, technique without or with flap creation and early or immediate load. This is a male patient aged 56 came to our multidisciplinary consultation worried because he had three prostheses in last two years and any fulfilled the requirements of retention to feel safe and comfortable with prostheses. The final result was the total satisfaction of rehabilitated patient improving its aesthetic and functional quality.

  1. Genetic analysis of environmental variation

    NARCIS (Netherlands)

    Hill, W.G.; Mulder, H.A.

    2010-01-01

    Environmental variation (VE) in a quantitative trait – variation in phenotype that cannot be explained by genetic variation or identifiable genetic differences – can be regarded as being under some degree of genetic control. Such variation may be either between repeated expressions of the same trait

  2. Genetic analysis of environmental variation

    NARCIS (Netherlands)

    Hill, W.G.; Mulder, H.A.

    2010-01-01

    Environmental variation (VE) in a quantitative trait – variation in phenotype that cannot be explained by genetic variation or identifiable genetic differences – can be regarded as being under some degree of genetic control. Such variation may be either between repeated expressions of the same trait

  3. Total Phenolics and Total Flavonoids in Selected Indian Medicinal Plants

    OpenAIRE

    C T Sulaiman; Indira Balachandran

    2012-01-01

    Plant phenolics and flavonoids have a powerful biological activity, which outlines the necessity of their determination. The phenolics and flavonoids content of 20 medicinal plants were determined in the present investigation. The phenolic content was determined by using Folin-Ciocalteu assay. The total flavonoids were measured spectrophotometrically by using the aluminium chloride colorimetric assay. The results showed that the family Mimosaceae is the richest source of phenolics, (Acacia ni...

  4. What is Total Quality Management?

    Science.gov (United States)

    Bryan, William A.

    1996-01-01

    Provides a general overview of Total Quality Management (TQM) and explains why there is pressure for change in higher education institutions. Defines TQM and the various themes, tools, and beliefs that make it different from other management approaches. Presents 14 principles and how they might be applied to student affairs. (RJM)

  5. The Total Cost of Technology.

    Science.gov (United States)

    Freeman, Jim

    2002-01-01

    Presents overview of areas to consider when planning for the total cost of technology, including a brief look at the planning needed, equipment that should be considered, infrastructure needs, software considerations, maintenance issues, training, upgrades, and planning for system failures. (Author/PKP)

  6. Leadership and Total Quality Management

    Science.gov (United States)

    1992-04-15

    Quality Management when combine with good leadership and management skills yields increased productivity. This paper will focus on the skills required of...The leadership of large and complex organizations in today’s environment of shrinking resources requires a strong commitment by the leader. Total

  7. Spraakrevalidatie na een totale laryngectomie

    NARCIS (Netherlands)

    Timmermans, A.J.; Krap, M.; Hilgers, F.J.M.; van den Brekel, M.W.M.

    2012-01-01

    In patients with advanced laryngeal or hypopharyngeal cancer, or in cases when the disease recurs after treatment with (chemo)radiation, a total laryngectomy (TLE) is performed. For them to be able to function properly, speech rehabilitation is of the utmost importance for these patients. For voice

  8. The Total Cost of Ownership.

    Science.gov (United States)

    Day, C. William

    2000-01-01

    Examines what Total Cost of Ownership is regarding the purchase of technological resources for schools and the major expenses that are likely to occur after technological hardware and software have been installed. A list of best practices that can reduce costs approximately 15 percent and a checklist for technology budgeting are provided. (GR)

  9. Total enantioselective synthesis of (-)-cytisine.

    Science.gov (United States)

    Danieli, Bruno; Lesma, Giordano; Passarella, Daniele; Sacchetti, Alessandro; Silvani, Alessandra; Virdis, Andrea

    2004-02-19

    [reaction: see text] The first total enantiosynthesis of the biologically active alkaloid (-)-cytisine is reported, featuring a ruthenium-catalyzed RCM reaction as the key step. The approach relies on readily available cis-piperidine-3,5-dimethanol monoacetate as the chiral building block, and it is suited for achieving the target compound in both enantiomeric forms.

  10. [Hypoparathyroid risk after total thyroidectomy].

    Science.gov (United States)

    Milone, Antonino; Carditello, Antonio; Stilo, Francesco; Paparo, Domenica; Paparo, Teresa

    2004-01-01

    From January 1970 to December 1999, 881 patients with thyroid pathology underwent surgery consisting in 551 subtotal thyroidectomies and 330 total thyroidectomies. Permanent hypocalcaemia was present in 32 patients (3.6%). The importance of accurate isolation and ultraligature of the branches of the inferior thyroid artery in the prevention of parathyroid damage is stressed.

  11. Total knee arthroplasty in elderly osteoporotic patients.

    Science.gov (United States)

    Spinarelli, Antonio; Petrera, Massimo; Vicenti, Giovanni; Pesce, Vito; Patella, Vittorio

    2011-04-01

    Often in daily practice the choice of a prosthesis does not rise out of considerations about literature evidences, but it seems to be related to the personal experience and "surgical philosophy" of surgeon. The choice of prosthesis in total joint replacement is usually justified by biological and mechanical parameters that the surgeon considers before surgery. Osteoporosis is a disease characterized by a reduced bone mass and a degeneration of the bone tissue; it leads to bone fragility, so to a higher risk of fractures. Bone resistance, as all the changes in the microarchitecture of the bone tissue, is linked to bone density. Because of the bone density variation and/or the changes in the bone micro-architecture, as the bone strength decreases, the risk of fractures increases. It is important to understand all the factors taking part in both normal and abnormal bone remodelling. Osteoporosis does not imply a concrete bone loss, but a change of the bone micro-architecture itself. In these cases the choice of the patient and implant design are very important. In the period between March 1997-July 2002, we implanted 100 consecutive TKA (total knee arthroplasty) Genesis II in 97 subjects (79 female); mean age was 77.1 years old. All TKA were performed because of primary osteoarthritis of the knee. All patients had complete pain relief and excellent knee score. The surgical and medical complications were in accordance with the published literature. We must consider all existing medical conditions, the state of the knee and local needs of the elderly patient. Thus, within these limits, the total knee can improve the ability of patients to manage the activities of daily living and improve their quality of life.

  12. A global reference for human genetic variation

    DEFF Research Database (Denmark)

    Auton, Adam; Abecasis, Goncalo R.; M. Altshuler, David

    2015-01-01

    The 1000 Genomes Project set out to provide a comprehensive description of common human genetic variation by applying whole-genome sequencing to a diverse set of individuals from multiple populations. Here we report completion of the project, having reconstructed the genomes of 2,504 individuals...... from 26 populations using a combination of low-coverage whole-genome sequencing, deep exome sequencing, and dense microarray genotyping. We characterized a broad spectrum of genetic variation, in total over 88 million variants (84.7 million single nucleotide polymorphisms (SNPs), 3.6 million short...... insertions/deletions (indels), and 60,000 structural variants), all phased onto high-quality haplotypes. This resource includes >99% of SNP variants with a frequency of >1% for a variety of ancestries. We describe the distribution of genetic variation across the global sample, and discuss the implications...

  13. On functions of bounded variation

    OpenAIRE

    Aistleitner, Christoph; Pausinger, Florian; Svane, Anne Marie; Tichy, Robert F.

    2015-01-01

    The recently introduced concept of $\\mathcal{D}$-variation unifies previous concepts of variation of multivariate functions. In this paper, we give an affirmative answer to the open question from Pausinger \\& Svane (J. Complexity, 2014) whether every function of bounded Hardy--Krause variation is Borel measurable and has bounded $\\mathcal{D}$-variation. Moreover, we show that the space of functions of bounded $\\mathcal{D}$-variation can be turned into a commutative Banach algebra.

  14. On distance variation effects on graphene bilayers

    Science.gov (United States)

    Naji, S.; Bhihi, M.; Labrim, H.; Belhaj, A.; Benyoussef, A.; El Kenz, A.; Loulidi, M.

    2014-06-01

    The opening of the energy gap and the total energy of the graphene-like bilayers are investigated using ab initio calculations. The studied model consists of a static single layer of graphene interacting with an extra dynamic one placed at a varying vertical distance d in the (AB) stacking arrangement. The effects of the vertical distance variation on the energy gap and the total energy of the system are discussed first. Starting from a distance around the van der Waals length, the energy gap does not depend on the vertical distance variation and the system exhibits graphene-like properties with minor deformations in the lattice size parameter and the energy dispersion behaviour around K points. However, it has been shown that the diagonal distance variation of the graphene-like bilayer modifies the electronic structure properties. This modification depends on an intermediate stacking arrangement between the (AA) and the (AB) configurations. It has been shown that the diagonal distance variation has an influence on the states of pz electrons in the (AB) arrangement and it can be explored to open the energy gap.

  15. Human immune system variation.

    Science.gov (United States)

    Brodin, Petter; Davis, Mark M

    2017-01-01

    The human immune system is highly variable between individuals but relatively stable over time within a given person. Recent conceptual and technological advances have enabled systems immunology analyses, which reveal the composition of immune cells and proteins in populations of healthy individuals. The range of variation and some specific influences that shape an individual's immune system is now becoming clearer. Human immune systems vary as a consequence of heritable and non-heritable influences, but symbiotic and pathogenic microbes and other non-heritable influences explain most of this variation. Understanding when and how such influences shape the human immune system is key for defining metrics of immunological health and understanding the risk of immune-mediated and infectious diseases.

  16. ARTHROFIBROSIS FOLLOWING TOTAL KNEE ARTHROPLASTY

    Directory of Open Access Journals (Sweden)

    Ravi B. Solanki

    2014-11-01

    Full Text Available Arthrofibrosis following total knee arthroplasty is an uncommon complication defined as less than 80 degrees of knee flexion 6-8 weeks post operatively. It is characterized by abnormal scarring of the joint in which the formation of dense fibrous tissue and tissue metaplasia prevent normal range of motion. Clinical features include limited knee Range of motion with extension deficit, pain with activities of daily living and unusual amount of pain and swelling post operatively in the absence of infection, bleeding or mechanical complications. We present case of 55 years old female who undergone for total knee replacement before 3 months and presented to our department with complain of knee pain and swelling with activities of daily living. She was diagnosed on the basis of clinical examination. Her detailed evaluation was carried out and Physiotherapy treatment was started.

  17. Rehabilitation for total joint arthroplasty.

    Science.gov (United States)

    Ritterman, Scott; Rubin, Lee E

    2013-05-01

    Total hip and knee replacement are two of the most common and successful elective surgeries preformed in the United States each year. Preoperative medical preparation and postoperative rehabilitation are equally important to a successful outcome. Physical deconditioning, tobacco use, obesity and medical co-morbidities can adversely affect outcomes and should be addressed before any elective procedure. Formal postoperative therapy is geared towards the specific surgery and is aimed at returning the patient to independent activity.

  18. Intrathoracic Hernia after Total Gastrectomy

    Directory of Open Access Journals (Sweden)

    Yoshihiko Tashiro

    2016-05-01

    Full Text Available Intrathoracic hernias after total gastrectomy are rare. We report the case of a 78-year-old man who underwent total gastrectomy with antecolic Roux-Y reconstruction for residual gastric cancer. He had alcoholic liver cirrhosis and received radical laparoscopic proximal gastrectomy for gastric cancer 3 years ago. Early gastric cancer in the remnant stomach was found by routine upper gastrointestinal endoscopy. We initially performed endoscopic submucosal dissection, but the vertical margin was positive in a pathological result. We performed total gastrectomy with antecolic Roux-Y reconstruction by laparotomy. For adhesion of the esophageal hiatus, the left chest was connected with the abdominal cavity. A pleural defect was not repaired. Two days after the operation, the patient was suspected of having intrathoracic hernia by chest X-rays. Computed tomography showed that the transverse colon and Roux limb were incarcerated in the left thoracic cavity. He was diagnosed with intrathoracic hernia, and emergency reduction and repair were performed. Operative findings showed that the Roux limb and transverse colon were incarcerated in the thoracic cavity. After reduction, the orifice of the hernia was closed by suturing the crus of the diaphragm with the ligament of the jejunum and omentum. After the second operation, he experienced anastomotic leakage and left pyothorax. Anastomotic leakage was improved with conservative therapy and he was discharged 76 days after the second operation.

  19. Chemical Composition of the Essential Oil, Total Phenolics, Total Flavonoids and Antioxidant Activity of Methanolic Extracts of Satureja montana L.

    Directory of Open Access Journals (Sweden)

    Avni Hajdari

    2016-05-01

    Full Text Available Aerial parts of Satureja montana L. (Lamiaceae were collected from seven growing wild populations (four populations in Kosovo, two in Albania and one in Montenegro in 2013 with the aim of assessing the natural variation in the chemical composition of the essential oils, total flavonoids, total phenolics and the antioxidant activity of their methanolic extracts. Essential oils were obtained by steam distillation and analysed using GC-FID and GC-MS, whereas total flavonoids, total phenolics and antioxidant activities were determined using spectrophotometric methods. Sixty-one volatile constituents were identified. The main constituents were myrcene, p-cymene, γ-terpinene, linalool, thymol, carvacrol and viridiflorol. Total phenolics ranged from 68.1 to 102.6 mg/g dry mass, the total flavonoid content ranged from 38.3 to 67.0 mg/g dm, and the antioxidant activity according to the DPPH assay ranged from 253.3 to 342.9 mg TE/g dm and according to the FRAP assay ranged from 8.9 to 11.4 mg TE/g dm. Hierarchical cluster analysis and principal component analyses were used to assess the geographical variations in the essential oil composition. Statistical analysis revealed that the analysed populations are grouped into four main clusters that appear to reflect the environmental impact on the chemical composition, which is influenced by differences in habitat composition, altitude and microclimatic conditions.

  20. Total Monomeric Anthocyanin and Total Flavonoid Content of Processed Purple

    Directory of Open Access Journals (Sweden)

    Potato Florentina Damşa

    2016-01-01

    Full Text Available It is well known that processing change physical and chemical composition of foods, thus affecting the content in bioactive substances. Potatoes are almost always consumed after processing (baked, fried or boiled making it critical to understand the effect of such processing techniques on the containing in bioactive compounds. In order to determine the influence of processing on the content of anthocyanin pigments and flavonoids was achieved the extraction of these compounds from boiled and baked purple potato tuber (Albastru-Violet de Galanesti variety. Also, in order to obtain the maximum amount of anthocyanin pigments and flavonoids from processed potatoes was applied ultrasonic extraction (20 kHz and was performed the mathematical modeling (central composite design using SigmaXL software. The total anthocyanins content were determined spectrophotometrically by the pH differential method and the total flavonoids content were determine colorimetric by AlCl3 method. This study proves that the potato processing decreases the content of anthocyanin pigments and flavonoids.

  1. Magnitudes and Timescales of Total Solar Irradiance Variability

    CERN Document Server

    Kopp, Greg

    2016-01-01

    The Sun's net radiative output varies on timescales of minutes to gigayears. Direct measurements of the total solar irradiance (TSI) show changes in the spatially- and spectrally-integrated radiant energy on timescales as short as minutes to as long as a solar cycle. Variations of ~0.01 % over a few minutes are caused by the ever-present superposition of convection and oscillations with very large solar flares on rare occasion causing slightly-larger measureable signals. On timescales of days to weeks, changing photospheric magnetic activity affects solar brightness at the ~0.1 % level. The 11-year solar cycle shows variations of comparable magnitude with irradiances peaking near solar maximum. Secular variations are more difficult to discern, being limited by instrument stability and the relatively short duration of the space-borne record. Historical reconstructions of the Sun's irradiance based on indicators of solar-surface magnetic activity, such as sunspots, faculae, and cosmogenic isotope records, sugge...

  2. Genetic variation and human longevity.

    Science.gov (United States)

    Soerensen, Mette

    2012-05-01

    The overall aim of the PhD project was to elucidate the association of human longevity with genetic variation in major candidate genes and pathways of longevity. Based on a thorough literature and database search we chose to apply a pathway approach; to explore variation in genes composing the DNA damage signaling, DNA repair, GH/IGF-1/insulin signaling and pro-/antioxidant pathways. In addition, 16 genes which did not belong to the core of either pathway, however recurrently regarded as candidate genes of longevity (e.g. APOE), were included. In this way a total of 168 genes were selected for investigation. We decided to explore the genetic variation in the form of single nucleotide polymorphisms (SNPs), a highly investigated type of genetic variation. SNPs having potential functional impact (e.g. affecting binding of transcription factors) were identified, so were specific SNPs in the candidate genes previously published to be associated with human longevity. To cover the majority of the common genetic variation in the 168 gene regions (encoding regions plus 5,000 bp upstream and 1,000 downstream) we applied the tagging SNP approach via the HapMap Consortium. Consequently 1,536 SNPs were selected. The majority of the previous publications on genetic variation and human longevity had employed a case-control study design, e.g. comparing centenarians to middle-aged controls. This type of study design is somehow prone to bias introduced by for instance cohort effects, i.e. differences in characteristics of cases and controls, a kind of bias which is avoided when a prospective cohort is under study. Therefore, we chose to investigate 1,200 individuals of the Danish 1905 birth cohort, which have been followed since 1998 when the members were 92-93 years old. The genetic contribution to human longevity has been estimated to be most profound during the late part of life, thus these oldest-old individuals are excellent for investigating such effect. The follow-up survival

  3. Variations in automatically recorded rumination time as explained by variations in intake of dietary fractions and milk production, and between-cow variation

    DEFF Research Database (Denmark)

    Byskov, Malene Vesterager; Nadeau, E.; Johansson, B. E. O.

    2015-01-01

    could be explained by variations in intakes of the dietary fractions, whereas 48% of the total variation in RT was accounted for by individual variations between cows. Intakes of forage NDF and starch were positively related to daily RT, whereas intakes of sugar and the rest fraction were negatively......Individual recording of rumination time (RT) is now possible in commercial dairy herds, through development of a microphone-based sensor, which is able to record RT by the sound of rumination activity. The objectives of this study were to examine the relationship between daily RT and intakes...... of different dietary fractions, the relationship between RT in minutes per kilogram of dry matter intake (DMI) and milk production, and to examine the variation in RT within and between mid-lactating dairy cows. Data from 3 production trials were used in which a total of 27 different diets were fed. The data...

  4. Capturing aerosol droplet nucleation and condensation bursts using PISO and TVD schemes

    NARCIS (Netherlands)

    Frederix, E.M.A.; Kuczaj, Arkadiusz K.; Nordlund, M.; Geurts, Bernardus J.

    2014-01-01

    A mathematical model for single-species aerosol production and transport is formulated, and solved using an adapted PISO algorithm. The model is applied to a laminar flow diffusion chamber, using a finite volume method on a collocated grid. In tran- sient simulations, a sharp scalar front (e.g.,

  5. Numerical methods for TVD transport and coupled relaxing processes in gases and plasmas

    Science.gov (United States)

    Cambier, Jean-Luc

    1990-01-01

    The construction of second-order upwind schemes for nonequilibrium plasmas, for both one- and two-fluid formulations is demonstrated. Coupled relaxation processes, including ionization kinetics and radiative processes and their algorithms for nonequilibrium, multiple temperature conditions are described as well. The paper applies the numerical techniques on some simple test cases, points out critical problems and their solutions, and makes qualitative comparisons with known results, whenever possible.

  6. Pressure-Based High-Order TVD Methodology for Dynamic Stall Control

    Science.gov (United States)

    1992-01-31

    Shari M. Shea and Ms. Jennifer L. Swann of CFDRC for their skillful preparation of the typescript of this report. I I I I I I I I ii I TABLE OF CONTENTS...sectional lift coefficient. Ashworth , et al.52 studied three-dimensional flow field about a forward swept NACA 0015 wing. They found that strong helical tip...occurred in the cycle. Ashworth , et al. 56,57, Luttges and M.C. Robinson 58, and Adler and Luttges59 have I made a series of studies on three

  7. A TVD uncertainty quantification method with bounded error applied to transonic airfoil flutter

    NARCIS (Netherlands)

    Witteveen, J.A.S.; Bijl, H.

    2009-01-01

    The Unsteady Adaptive Stochastic Finite Elements (UASFE) approach is a robust and efficient uncertainty quantification method for resolving the effect of random parameters in unsteady simulations. In this paper, it is shown that the underlying Adaptive Stochastic Finite Elements (ASFE) method for st

  8. Heliophysics at total solar eclipses

    Science.gov (United States)

    Pasachoff, Jay M.

    2017-08-01

    Observations during total solar eclipses have revealed many secrets about the solar corona, from its discovery in the 17th century to the measurement of its million-kelvin temperature in the 19th and 20th centuries, to details about its dynamics and its role in the solar-activity cycle in the 21st century. Today's heliophysicists benefit from continued instrumental and theoretical advances, but a solar eclipse still provides a unique occasion to study coronal science. In fact, the region of the corona best observed from the ground at total solar eclipses is not available for view from any space coronagraphs. In addition, eclipse views boast of much higher quality than those obtained with ground-based coronagraphs. On 21 August 2017, the first total solar eclipse visible solely from what is now United States territory since long before George Washington's presidency will occur. This event, which will cross coast-to-coast for the first time in 99 years, will provide an opportunity not only for massive expeditions with state-of-the-art ground-based equipment, but also for observations from aloft in aeroplanes and balloons. This set of eclipse observations will again complement space observations, this time near the minimum of the solar activity cycle. This review explores the past decade of solar eclipse studies, including advances in our understanding of the corona and its coronal mass ejections as well as terrestrial effects. We also discuss some additional bonus effects of eclipse observations, such as recreating the original verification of the general theory of relativity.

  9. Diverticulosis in total colonic aganglionosis

    Energy Technology Data Exchange (ETDEWEB)

    Ivancev, K.; Fork, T.; Haegerstrand, I.; Ivarsson, S.; Kullendorff, C.M.

    Two infants with total colonic aganglionosis (TCA) extending into the distal part of the ileum are described. Considerable diagnostic delay occurred with the correct diagnosis established first at 3 and 8 months, respectively. Radiologic findings compatible with TCA such as prolonged barium retention, reflux into ileum following barium enema, and foreshortening of colon were not clearly evident initially. Both patients demonstrated multiple acquired colon diverticula which increased both in number and size during the period of observation. These diverticula are probably a late manifestation of the spastic state of the anganglionic colon. Thus demonstration of diverticula supplies a strong evidence of TCA in infants with intestinal obstruction. (orig.).

  10. Total light absorption in graphene

    CERN Document Server

    Thongrattanasiri, Sukosin; de Abajo, F Javier Garcia

    2011-01-01

    We demonstrate that 100% light absorption can take place in a single patterned sheet of doped graphene. General analysis shows that a planar array of small lossy particles exhibits full absorption under critical-coupling conditions provided the cross section of each individual particle is comparable to the area of the lattice unit-cell. Specifically, arrays of doped graphene nanodisks display full absorption when supported on a substrate under total internal reflection, and also when lying on a dielectric layer coating a metal. Our results are relevant for infrared light detectors and sources, which can be made tunable via electrostatic doping of graphene.

  11. The total synthesis of (-)-nitidasin.

    Science.gov (United States)

    Hog, Daniel T; Huber, Florian M E; Mayer, Peter; Trauner, Dirk

    2014-08-01

    Nitidasin is a pentacyclic sesterterpenoid with a rare 5-8-6-5 carbon skeleton that was isolated from the Peruvian folk medicine "Hercampuri". It belongs to a small class of sesterterpenoids that feature an isopropyl trans-hydrindane moiety fused to a variety of other ring systems. As a first installment of our general approach toward these natural products, we report the total synthesis of the title compound. Our stereoselective, convergent route involves the addition of a complex alkenyl lithium compound to a trans-hydrindanone, followed by chemoselective epoxidation, ring-closing olefin metathesis, and redox adjustment.

  12. Radiology of total hip replacement

    Energy Technology Data Exchange (ETDEWEB)

    Griffiths, H.J.; Lovelock, J.E.; McCollister Evarts, C.; Geyer, D.

    1984-06-01

    The radiology of total hip replacement (THR) and its complications is reviewed in conjunction with a long-term follow-up study on 402 patients with 501 prostheses. The indications, contraindications, biomechanics, and operative management of these patients is discussed. Clinical complications such as deep vein thrombosis, pulmonary embolism, and hemorrhage are mentioned. Postoperative infections including granulomatous pseudotumors, dislocations and fractures, true loosening of the prosthesis, and heterotopic bone formation (HBF) are discussed and illustrated. The importance of differentiating the lucent line from true loosening is stressed. Mechanical and other clinical complications which are largely ignored by radiologists are also discussed. The uses of arthrography and bone scanning are included.

  13. Total eclipses of the sun

    CERN Document Server

    Zirker, Jack B

    2014-01-01

    Eclipses have captured attention and sparked curiosity about the cosmos since the first appearance of humankind. Having been blamed for everything from natural disasters to the fall of kings, they are now invaluable tools for understanding many celestial as well as terrestrial phenomena. This clear, easy-to-understand guide explains what causes total eclipses and how they can be used in experiments to examine everything from the dust between the planets to general relativity. A new chapter has been added on the eclipse of July 11, 1991 (the great Hawaiian eclipse). Originally published in 19

  14. First total synthesis of Boehmenan

    Indian Academy of Sciences (India)

    Yamu Xia; Xiaoli Dai; Haixin Liu; Chen Chai

    2014-05-01

    The first total synthesis of dilignan Boehmenan has been achieved. A biomimetic oxidative coupling of the ferulic acid methyl ester in the presence of silver oxide is the crucial step in the synthesis sequence, generating the dihydrobenzofuran skeleton. Hydroxyl group was protected with DHP and reducted with LiAlH4 to afford the intermediate diol. The diol was condensated with the derivative of ferulic acid, then removed the protecting groups, to get Boehmenan. Meanwhile, a study on the ring-opening reaction of the intermediate dihydrobenzofuran neolignan under base conditions was described.

  15. [Proximal and total femur replacement].

    Science.gov (United States)

    Pennekamp, P H; Wirtz, D C; Dürr, H R

    2012-07-01

    Reconstruction of segmental bone defects of the proximal femur following wide tumor resection or revision arthroplasty. Aggressive benign or primary malignant bone tumors of the proximal femur; destructive metastases; massive segmental bone defects of the proximal femur; periprosthetic fractures. Local infection; very short life expectancy (acetabular bone stock. Anterolateral approach. Exposure and detachment of the iliopsoas and gluteus medius muscle from the proximal femur with a sufficient safety margin to the bone; distal transsection of the vastus lateralis/intermedius and rectus femoris muscle according to the extraosseous tumor extension; distal femur osteotomy al least 3 cm beyond the farthest point of tumor extension; in case of total femur replacement, additional lateral arthrotomy of the knee with resection of the ligaments and menisci; reaming of the medullary canal after securing the shaft with a Verbrugge clamp; trial assembly and reduction followed by the definitive implantation of the prosthesis with adjustment of the femoral neck anteversion in 5° increments; soft tissue reconstruction and fixation to an attachment tube covering the prosthesis; in case of total femur replacement, the preparation of the tibia is followed by the coupling of the tibial and femoral components. Infection prophylaxis, 20 kg partial weight bearing, continuous passive motion. A total of 20  patients with proximal femur replacement and 2 patients with total femur replacement implanted between June 2007 and December 2011 were retrospectively reviewed. Three patients had primary malignant bone tumors, while 19 patients underwent resection for metastatic disease. The mean age at surgery was 62.0 ± 18.1 years (18-82 years). Fifteen patients with a mean follow-up of 20.3 ± 17.2 months (4-51 months) were studied. Among the 22 cases, periprosthetic infection occurred in 3 patients (13.6%), dislocation in 2 patients (9.1%). Evaluation of the functional

  16. A new reconstruction of total solar irradiance since 1832

    Energy Technology Data Exchange (ETDEWEB)

    Vaquero, J.M. [Departamento de Fisica, Escuela Politecnica, Universidad de Extremadura, Caceres (Spain); Gallego, M.C. [Departamento de Fisica, Universidad de Extremadura, Badajoz (Spain); Trigo, R.M. [Centro de Geofisica da Universidade de Lisboa, Departamento de Engenharias, Lisboa (Portugal); Sanchez-Bajo, F [Escuela de Ingenieros Industriales, Universidad de Extremadura, Badajoz (Spain); Cancillo, M.L.; Garcia, J.A. [Departamento de Fisica, Universidad de Extremadura, Badajoz (Spain)

    2006-10-15

    Variations of solar irradiance (total and spectral) are quantities purported to have an influence on climate. The aim of this paper is to reconstruct the total solar irradiance from 1832 to the present. The contributions of active regions and the quiet sun are modelled separately using the method developed by Solanki and Fligge (1999). The areas of sunspots observed since 1832 are used to compute the contribution of active regions to the irradiance changes. [Spanish] Diferentes autores han propuesto que las variaciones de la irradiancia solar total y espectral son magnitudes que pueden influir en el clima. El objetivo de este articulo es reconstruir la irradiancia solar total desde 1832 hasta el presente. Las contribuciones de las regiones activas y del 'sol quieto' se modelan separadamente usando el metodo de Solanki y Fligge (1999). El area de las manchas solares desde 1832 es utilizada para calcular la contribucion de las regiones activas a los cambios en la irradiancia.

  17. Surgical anatomy of double pyramidal lobe on total thyroidectomy: a rare case report

    Science.gov (United States)

    Kaklamanos, Ioannis; Flessas, Ioannis; Zoulamoglou, Menelaos; Katsoulas, Theodoros; Birbas, Konstantinos; Troupis, Theodoros; Mariolis-Sapsakos, Theodoros

    2017-01-01

    Abstract Double pyramidal lobe is a scarce anatomical variation of the thyroid gland. Its presence impinges on the completeness of total and subtotal thyroidectomy and the postoperative treatment. Surgeons should be always aware of this variation in order to perform sufficient resection of the thyroid gland and minimize the possibility of recurrence of benign and malignant thyroidopathies. PMID:28458845

  18. An improved variational method

    Institute of Scientific and Technical Information of China (English)

    ZENG Zhuo-Quan; SHEN Peng-Nian; DING Yi-Bing

    2009-01-01

    In order to improve the unitarity of the S-matrix, an improved variational formulism is derived by proposing new generating functionals and adopting proper asymptotic boundary conditions for trial relative wave functions. The formulas with the weighted line-column balance for the single-channel and multi-channel scatterings, where the non-central interaction is implicitly considered, are presented. A numerical check is performed with a soluble model in a four coupled channel scattering problem. The result shows that the high accuracy and the unitarity of the S-matrix are reached.

  19. Semantic segmentation of colon glands with deep convolutional neural networks and total variation segmentation

    OpenAIRE

    2015-01-01

    Segmentation of histopathology sections is an ubiquitous requirement in digital pathology and due to the large variability of biological tissue, machine learning techniques have shown superior performance over standard image processing methods. As part of the GlaS@MICCAI2015 colon gland segmentation challenge, we present a learning-based algorithm to segment glands in tissue of benign and malignant colorectal cancer. Images are preprocessed according to the Hematoxylin-Eosin staining protocol...

  20. Variation in Total Polyphenolics Contents of Aerial Parts of Potentilla Species and Their Anticariogenic Activity

    Directory of Open Access Journals (Sweden)

    Michał Tomczyk

    2010-06-01

    Full Text Available The aerial parts of selected Potentilla species (P. anserina, P. argentea, P. erecta, P. fruticosa, P. grandiflora, P. nepalensis, P. norvegica, P. pensylvanica, P. crantzii and P. thuringiaca were investigated in order to determine their contents of polyphenolic compounds. The results showed that P. fruticosa has relatively high concentrations of tannins (167.3 ± 2.0 mg/g dw, proanthocyanidins (4.6 ± 0.2 mg/g dw and phenolic acids (16.4 ± 0.8 mg/g dw, as well as flavonoids (7.0 ± 1.1 mg/g dw, calculated as quercetin. Furthermore, we investigated the in vitro inhibitory effects of aqueous extracts from these species against cariogenic Streptococcus spp. strains. It was found that the tested samples moderately inhibit the growth of oral streptococci. However, all the preparations exhibited inhibitory effects on water-insoluble α-(1→3-, α-(1→6-linked glucan (mutan and artificial dental plaque formation. The extract from P. fruticosa showed the highest anti-biofilm activities, with minimum mutan and biofilm inhibition concentrations of 6.25–25 and 50–100 µg/mL, respectively. The results indicate that the studied Potentilla species could be a potential plant material for extracting biologically active compounds, and could become a useful supplement for pharmaceutical products as a new anticariogenic agent in a wide range of oral care products.