1,371 research outputs found
F Approach Algorithm in Missing Landmark Problem
No full textMissing data may occur in every scientific studies. Statistical shape analysis involves methods that use geometric information obtained from objects. The most important input to the use of geometric information in statistical shape analysis is landmarks. Missing data in shape analysis occurs when there is a loss of information about landmark cartesian coordinates. The aim of the study is to propose F approach algorithm for estimating missing landmark coordinates and compare the performance of F approach with generally accepted missing data estimation methods, EM algorithm, PCA based methods such as Bayesian PCA, Nonlinear Estimation by Iterative Partial Least Squares PCA, Inverse non-linear PCA, Probabilistic PCA and regression imputation methods. Landmark counts were taken as 3, 6, 9 and sample sizes were taken as 5, 10, 30, 50, 100 in the simulation study. The data are generated based on multivariate normal distribution with positively defined variance-covariance matrices from isotropic models. In simulation study three different simulation scenarios and simulation based real data are considered with 1000 repetations. The best and the most different result in the performance evaluation according to all sample sizes is the Min (F) criteria of the F approach algorithm proposed in the study. In case of three landmarks which is only the proposed F approach and regression assignment method can be applied, Min (F) criteria give best results
The Banach–Stone theorem revisited
No full textAbstractLet X and Y be compact Hausdorff spaces, and E and F be locally solid Riesz spaces. If π:C(X,E)→C(Y,F) is a 1-biseparating Riesz isomorphism then X and Y are homeomorphic, and E and F are Riesz isomorphic. This generalizes the main results of [Z. Ercan, S. Önal, Banach–Stone theorem for Banach lattice valued continuous functions, Proc. Amer. Math. Soc. 135 (9) (2007) 2827–2829] and [X. Miao, C. Xinhe, H. Jiling, Banach–Stone theorems and Riesz algebras, J. Math. Anal. Appl. 313 (1) (2006) 177–183], and answers a conjecture in [Z. Ercan, S. Önal, Banach–Stone theorem for Banach lattice valued continuous functions, Proc. Amer. Math. Soc. 135 (9) (2007) 2827–2829]
Exogenous Testosterone and Estrogen Affect Bladder Tissue Contractility and Histomorphology Differently in Rat Ovariectomy Model
No full textIntroduction. Changes in sex hormone levels may play a role in the etiology of lower urinary tract dysfunction of aging women where the possible role of testosterone is overlooked. Aim. To determine the effect of testosterone with/without estrogen replacement on histological and functional deterioration in ovariectomized rat bladder tissue. Methods. A total of 54 female Sprague Dawley rats were divided into 6 groups. Except sham operated (control group), all others underwent bilateral ovariectomy. No further treatment was given to the ovariectomy-only group (OVX group). At the third week of ovariectomy treatments were started; vehicle agent (VA group), estradiol (E2 group), testosterone undecanoate (T group), and estradiol + testosterone undecanoate combination (E2 + T group) in physiological doses. Nine weeks after ovariectomy, bladder strips were harvested for isometric tension and histopathological studies. Main Outcome Measures. To assess the effect of testosterone/estradiol on ovariectomized rat bladder tissue function and histomorphology. Results. OVX and VA groups showed statistically significant histological changes such as urothelial damage, inflammatory cell infiltration, increase in collagen fibers and muscular atrophy compared with the control group. Both E2 and T reversed these changes but best histomorphological restoration was observed in E2 + T group. In isometric tension studies, ovariectomy tended to increase contractile responses which were normalized after E2 treatment. In contrary to E2, T significantly increased contractile responses that were normalized with combination treatment. During relaxation studies statistically significant higher relaxation responses were observed in ovariectomized rats. Although both exogenous testosterone and estradiol tended to reverse this effect, a statistically significant difference was found only after testosterone treatment. Conclusion. Either estradiol or testosterone replacement alone or in combination prevents significant alterations in bladder tissue histology following ovariectomy whereas both affect the bladder tissue contractility. Thus, combination treatment appears to be the best method to restore both contractility and histomorphology of bladder tissue after ovariectomy. Tanidir Y, Ercan F, and Tarcan T. Exogenous testosterone and estrogen affect bladder tissue contractility and histomorphology differently in rat ovariectomy model. J Sex Med 2011;8:1626-1637
Küçük deney hayvanlarından rat: editörler: orhan yücel, onur genç. Siçanlarla yapılan deneysel çalışmalarda mast hücrelerinin enflamasyondaki rolü
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Simulation based optimization for world line card production system
No full textApak, Sinan (Arel Author), Ercan, Sami (Arel Author)Simulation based decision support system is one of the most commonly used tools to examine complex production systems. The simulation approach provides process modules which can be adjusted with certain parameters by using data relatively easily obtainable in production process. World Line Card production system simulation is developed to evaluate the optimality of existing production line via using discrete event simulation model with variety of alternative proposals. The current production system is analysed by a simulation model emphasizing the bottlenecks and the poorly utilized production line. Our analysis identified some improvements and efficient solutions for the existing system
Modal properties of parallel plate waveguide partially loaded with double negative materials
No full textPekmezci, Ayşegül (Dogus Author) -- Topuz, Ercan (Dogus Author)Properties of eigen-solutions in parallel plate waveguides partially loaded with Lorentz type Double Negative Materials (DNG), modelled by lossless/lossy, identical/non-identical electric, magnetic parameters are presented. Modal cut-off phenomena associated with surface waves, transitions between evanescent/propagating, forward/backward waves and their dependence on frequency, filling factor and dispersive material parameters are investigated. Novel conditions are given for the existence of surface waves and for the emergence of complex eigenvalues in the absence of losses, and supported with numerical results of exact frequency domain analysis
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