Browsing by Author "Çetin, M"

Now showing 1 - 9 of 9
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    PARALLEL SURFACES TO TRANSLATION SURFACES IN EUCLIDEAN 3-SPACE
    Çetin, M; Tunçer, Y
    In this paper, we investigate geometric properties of surfaces that are parallel to translation surfaces in 3-dimensional Euclidean space which are constructed by generator curves with constant curvatures and torsions are given.
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    Lucas Polynomial Approach for System of High-Order Linear Differential Equations and Residual Error Estimation
    Çetin, M; Sezer, M; Güler, C
    An approximation method based on Lucas polynomials is presented for the solution of the system of high-order linear differential equations with variable coefficients under the mixed conditions. This method transforms the system of ordinary differential equations (ODEs) to the linear algebraic equations system by expanding the approximate solutions in terms of the Lucas polynomials with unknown coefficients and by using the matrix operations and collocation points. In addition, the error analysis based on residual function is developed for present method. To demonstrate the efficiency and accuracy of the method, numerical examples are given with the help of computer programmes written in Maple and Matlab.
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    Asymmetric dimethylarginine levels and diabetes duration: Relationship with measures of subclinical atherosclerosis and cardiac function in children and adolescents with Type 1 diabetes
    Ersoy, B; Eroglu, N; Çetin, M; Onur, E; Özkol, M; Coskun, S
    Aims: We aimed to evaluate asymmetric dimethylarginine levels in young patients with Type 1 diabetes mellitus according to diabetes duration and to examine the relationship between these levels and measures of atherosclerosis and myocardial function. Materials and methods: In total, 83 patients (8.5-22years) with Type 1 diabetes mellitus were stratified by diabetes duration: 12-60months (Group 1, n=27), >60-120months (Group 2, n=29) and >120months (Group 3, n=27). Asymmetric dimethylarginine levels were assessed. Carotid intima-media thickness was measured. Myocardial function was assessed by M-mode, conventional Doppler and tissue Doppler echocardiography. Results: Asymmetric dimethylarginine level was significantly higher in Group 1, while carotid intima-media thickness was significantly greater in Group 3 (p<0.05). Tissue Doppler echocardiography showed the ratio of peak early to peak late diastolic myocardial annular velocity decreased significantly in Groups 2 and 3 with a negative correlation with duration (r: -0.310, p=0.004) and HBA1c levels (r=-0.391, p<0.001). Myocardial performance index in all groups and isovolumic relaxation time in Group 3 increased significantly. Asymmetric dimethylarginine levels were negatively correlated with carotid intima-media thickness and isovolumic relaxation time (p<0.05). Conclusion: In contrast to adult diabetics, asymmetric dimethylarginine concentration decreases as diabetes duration increases in young Type 1 diabetic patients and is associated with worsening measures of cardiovascular risk and poorer diastolic function.
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    Vein of Galen aneurysm that was diagnosed prenatally and supracardiac obstructed total anomalous pulmonary venous return with pulmonary hypertension: case report
    Tanriverdi, S; Baytur, Y; Tansug, N; Çetin, M; Coskun, S
    The vein of Galen aneurysm is the most common form of symptomatic cerebrovascular malformation in neonates and infants. This anomaly may be diagnosed prenatally by several imaging modalities and causes high cardiac output, which may lead to cardiac failure, in newborns. Total anomalous pulmonary venous return is a rare entity that makes up approximately 0.4%-2% of all congenital heart diseases. The most common type of total anomalous pulmonary venous return is the supracardiac type. The pulmonary veins drain to a confluence posterior to the heart and then to a vertical vein, most commonly on the left, which enters the innominate vein and the drains to the right atrium. Obstructed pulmonary veins with supracardiac- type total anomalous pulmonary venous return can cause severe cardiac and respiratory failure. In this article, a case of a neonate with a vein of Galen aneurysm diagnosed prenatally by magnetic resonance imaging, and a supracardiac obstructed type of total anomalous pulmonary venous return with pulmonary hypertension is presented.
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    An Efficient Method Based on Lucas Polynomials for Solving High-Order Linear Boundary Value Problems
    Çetin, M; Sezer, M; Kocayigit, H
    In this paper, a collocation method based on Lucas polynomials for solving high-order linear differential equations with variable coefficients under the boundary conditions is presented by transforming the problem into a system of linear algebraic equations with Lucas coefficients. The proposed approach is applied to fourth, fifth, sixth and eighth-order two-point boundary values problems occurring in science and engineering, and compared by existing methods. The technique gives better approximations than other methods, and has a lower computational cost. In addition, the error analysis based on residual function is developed for the present method and the improved approximate solution is obtained. Moreover, numerical examples are included to illustrate the practical usefulness and efficiency of the method.
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    Timelike Curves of Constant Breadth According to Bishop Frame in Minkowski 3-Space
    Kocayigit, H; Çetin, M; Evirgen, MÇ
    In this study, the timelike curves of constant breadth according to Bishop frame in Minkowski 3-space are investigated. The differential equations characterizing the timelike curves of constant breadth in E-1(3) are given. In addition, it is shown that the timelike curves of constant breadth are related to slant helix in Minkowski 3-space E-1(3).
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    Assessment of pulmonary artery pressure and right ventricular function in children with adenotonsillar hypertrophy using different parameters
    Çetin, M; Yilmaz, M; Özen, S; Bozan, N; Coskun, S
    Objective: Our aim was comparison of preoperative and postoperative right ventricular functions of children with adenotonsillar hypertrophy (ATH) who have findings of upper airway obstruction, using new echocardiographic parameters. Methods: Forty-one children who have admitted to our hospital with symptoms suggestive of upper airway obstruction, whose history and physical examination findings suggest upper airway obstruction and who have undergone adenoidectomy/adenotonsillectomy and 40 healthy children, all of whom between 2 and 12 years of age, were included in the study. Patient group was evaluated by pulsed wave tissue Doppler echocardiography as well as with conventional echocardiography before the operation and 6 months after the operation. Results: Of 41 children in study group, 26 (63.4%) had adenotonsillectomy and 15 (36.6%) had adenoidectomy. Tricuspid annular plane systolic excursion (TAPSE) was significantly lower in preoperative group compared to control group (18.46 +/- 1.67, 19.77 +/- 1.62; p = 0.000, respectively). Myocardial performance index (MPI) was significantly higher in preoperative group than postoperative and control group (0.40 +/- 0.07, 0.36 +/- 0.06, 0.35 +/- 0.07; p = 0.032, respectively). Tricuspid isovolumic acceleration (TIVA) was significantly lower in preoperative group than preoperative and control group (2.97 +/- 0.8, 3.43 +/- 0.7, 3.43 +/- 0.9; p = 0.020, respectively). Disappearance of this difference was found between postoperative and control groups (p = 0.984). Pulmonary acceleration time (PAcT) was found to be significantly lower in preoperative group compared to postoperative and control group (109.68 +/- 18.03, 118.93 +/- 17.46, 120.0 +/- 14.07; p = 0.010, respectively). Mean pulmonary artery pressure (mPAP) was significantly higher in preoperative group than control group (29.64 +/- 8.11, 24.95 +/- 6.33; p = 0.010, respectively). In postoperative group mPAP was found to be similar to control group (25.48 +/- 7.85, 24.95 +/- 633; p = 0.740, respectively). Conclusions: TAPSE, PAcT, MPI and TIVA are useful markers for evaluation of preoperative and postoperative ventricular function in children with ATH who have findings of upper airway obstruction. We think that using these practical and easy-to perform parameters may be relevant for evaluation and postoperative follow-up of patients with ATH who have findings of upper airway obstruction. Besides adenotonsillectomy is a beneficial treatment option for these patients. (C) 2014 Elsevier Ireland Ltd. All rights reserved.
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    Outcomes of high-risk breast lesions diagnosed using image-guided core needle biopsy: results from a multicenter retrospective study
    Oktay, A; Aslan, Ö; Taskin, F; Tunçbilek, N; Içten, SGE; Balci, P; Aribal, ME; Çelik, L; Örguç, IS; Demirkazik, FB; Gültekin, S; Aydin, AM; Durmaz, E; Kul, S; Binokay, F; Çetin, M; Emlik, GD; Akpinar, MG; Voyvoda, SNK; Polat, AV; Akin, IB; Yildiz, S; Poyraz, N; Özsoy, A; Öztekin, PS; Elverici, E; Bayrak, IK; Ikizceli, T; Dinç, F; Sezgin, G; Gülsen, G; Tunçbilek, I; Yalçin, SR; Çolakoglu, G; Aglamis, S; Yilmaz, R; Rona, G; Durhan, G; Güner, DC; Yabul, FÇ; Karabekmez, LG; Tutar, B; Göktas, M; Bugdayci, O; Suner, A; Özdemir, N
    PURPOSE The clinical management of high-risk lesions using image-guided biopsy is challenging. This study aimed to evaluate the rates at which such lesions were upgraded to malignancy and identify possible predictive factors for upgrading high-risk lesions. METHODS This retrospective multicenter analysis included 1.343 patients diagnosed with high-risk lesions using an image-guided core needle or vacuum-assisted biopsy (VAB). Only patients managed using an excisional biopsy or with at least one year of documented radiological follow-up were included. For each, the Breast Imaging Reporting and Data System (BI-RADS) category, number of samples, needle thickness, and lesion size were correlated with malignancy upgrade rates in different histologic subtypes. Pearson's chi-squared test, the Fisher-Freeman-Halton test, and Fisher's exact test were used for the sta-tistical analyses. RESULTS The overall upgrade rate was 20.6%, with the highest rates in the subtypes of intraductal papilloma (IP) with atypia (44.7%; 55/123), followed by atypical ductal hyperplasia (ADH) (38.4%; 144/375), lobular neoplasia (LN) (12.7%; 7/55), papilloma without atypia (9.4%; 58/611), flat epithelial atypia (FEA) (8.7%; 10/114), and radial scars (RSs) (4.6%; 3/65). There was a significant relationship between the upgrade rate and BI-RADS category, number of samples, and lesion size Lesion size was the most predictive factor for an upgrade in all subtypes.CONCLUSION ADH and atypical IP showed considerable upgrade rates to malignancy, requiring surgical excision. The LN, IP without atypia, pure FEA, and RS subtypes showed lower malignancy rates when the BI-RADS category was lower and in smaller lesions that had been adequately sampled using VAB. After being discussed in a multidisciplinary meeting, these cases could be managed with follow-up instead of excision.