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Search Results (27)
  • Open Access

    ARTICLE

    Robust EM Algorithm for Iris Segmentation Based on Mixture of Gaussian Distribution

    Fatma Mallouli

    Intelligent Automation & Soft Computing, Vol.25, No.2, pp. 243-248, 2019, DOI:10.31209/2019.100000069

    Abstract Density estimation via Gaussian mixture modelling has been successfully applied to image segmentation. In this paper, we have learned distributions mixture model to the pixel of an iris image as training data. We introduce the proposed algorithm by adapting the Expectation-Maximization (EM) algorithm. To further improve the accuracy for iris segmentation, we consider the EM algorithm in Markovian and non Markovian cases. Simulated data proves the accuracy of our algorithm. The proposed method is tested on a subset of the CASIA database by Chinese Academy of Sciences Institute of Automation-IrisTwins. The obtained results have shown a significant improvement of our… More >

  • Open Access

    ARTICLE

    A Novel Technique for Estimating the Numerical Error in Solving the Helmholtz Equation

    Kue-Hong Chen1, *, Cheng-Tsung Chen2, 3

    CMC-Computers, Materials & Continua, Vol.64, No.1, pp. 145-160, 2020, DOI:10.32604/cmc.2020.08864

    Abstract In this study, we applied a defined auxiliary problem in a novel error estimation technique to estimate the numerical error in the method of fundamental solutions (MFS) for solving the Helmholtz equation. The defined auxiliary problem is substituted for the real problem, and its analytical solution is generated using the complementary solution set of the governing equation. By solving the auxiliary problem and comparing the solution with the quasianalytical solution, an error curve of the MFS versus the source location parameters can be obtained. Thus, the optimal location parameter can be identified. The convergent numerical solution can be obtained and… More >

  • Open Access

    ARTICLE

    Prevalence of Noonan spectrum disorders in a pediatric population with valvar pulmonary stenosis

    Kailyn Anderson1, James Cnota2,3, Jeanne James4,5, Erin M. Miller2,3, Ashley Parrott3, Valentina Pilipenko1,2, Kathryn Nicole Weaver1,2, Amy Shikany3

    Congenital Heart Disease, Vol.14, No.2, pp. 264-273, 2019, DOI:10.1111/chd.12721

    Abstract Objective: To evaluate the prevalence of Noonan spectrum disorders (NSD) in a pediatric population with valvar pulmonary stenosis (vPS) and identify the clinical characteristics that differentiate those with NSD from those without NSD.
    Design: A retrospective chart review of 204 patients diagnosed with vPS between 9/1/2012 and 12/1/2016 at a pediatric medical center was performed. The quantitative features of vPS, genetic diagnosis information, and phenotypic characteristics of Noonan syndrome were collected. Chi‐square test, Fisher’s exact test, t test, Wilcoxon rank‐sum test, and ANOVA were used for comparisons among the groups. Logistic regression was used to test for the association between… More >

  • Open Access

    ARTICLE

    PDA: To treat or not to treat

    Meera N. Sankar, Shazia Bhombal, William E. Benitz

    Congenital Heart Disease, Vol.14, No.1, pp. 46-51, 2019, DOI:10.1111/chd.12708

    Abstract Management of patent ductus arteriosus in extremely preterm infants remains a topic of debate. Treatment to produce ductal closure was widely practiced until the past decade, despite lack of evidence that it decreases morbidities or mortality. Meta‐analyses of trials using nonsteroidal anti‐inflammatory drugs have shown ef‐ fectiveness in accelerating ductal closure, but no reduction in neonatal morbidities, regardless of agent used, indication, timing, gestational age, or route of administra‐ tion. Surgical ligation closes the ductus but is associated with adverse effects. Recent experience with conservative approaches to treatment suggest improved neonatal outcomes and a high rate of spontaneous ductal closure… More >

  • Open Access

    ARTICLE

    Hemodynamically significant patent ductus arteriosus and the development of bronchopulmonary dysplasia

    Kent A. Willis, Mark F. Weems

    Congenital Heart Disease, Vol.14, No.1, pp. 27-32, 2019, DOI:10.1111/chd.12691

    Abstract Patent ductus arteriosus (PDA) is prevalent in premature newborns and has been linked to the development of bronchopulmonary dysplasia (BPD), a serious pulmonary complication of premature birth. Although a causal relationship has not been proven, the link is greatest among infants born at lower gestational age who are treated with mechanical ventilation in the presence of a large ductal shunt. Despite strong association in epidemiological studies, treatment of a patent ductus arteriosus has not been shown to prevent BPD, and some therapies may increase the risk of BPD. We describe preclinical and clinical data demonstrating the association of a PDA… More >

  • Open Access

    ARTICLE

    Study on the Contact Stress Concentration and the Hyperplasia of the Canine Trachea Granulation Tissue after Stenting

    Molecular & Cellular Biomechanics, Vol.15, No.1, pp. 51-61, 2018, DOI:10.3970/mcb.2018.015.051

    Abstract Tracheal stenosis is a common respiratory disease and is usually treated by stent implantation. However, the implanted stent often causes excessive hyperplasia of trachea granulation tissue, leading to the restenosis. Although surgical removal or chemical suppression can be used to alleviate the restenosis, the efficacy is limited. Thus, restenosis remains a thorny complication. We investigated this issue from the perspective of the “tress-growth”relationship. Firstly, the lower airway of 5 experimental dogs were CT-scanned to reconstruct the 3D numerical models; secondly, the implantations of the Nitinol alloy stents were numerically simulated; thirdly, 45 days after the stenting, the dogs were evaluated… More >

  • Open Access

    ARTICLE

    Numerical Simulations of Pulsatile Flow in an End-to-Side Anastomosis Model

    E. Shaik, K.A. Hoffmann, J-F. Dietiker

    Molecular & Cellular Biomechanics, Vol.4, No.1, pp. 41-54, 2007, DOI:10.3970/mcb.2007.004.041

    Abstract A potential interaction between the local hemodynamics and the artery wall response has been suggested for vascular graft failure by intimal hyperplasia (IH). Among the various hemodynamic factors, wall shear stress has been implicated as the primary factor responsible for the development of IH. In order to explore the role of hemodynamics in the formation of IH in end-to-side anastomosis, computational fluid dynamics is employed. To validate the numerical simulations, comparisons with existing experimental data are performed for both steady and pulsatile flows. Generally, good agreement is observed with the velocity profiles whereas some discrepancies are found in wall shear… More >

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