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Serkan Öner,Ays¸egül Sag˘ır Kahraman,Cemal Özcan,Zeynep Maras¸ Özdemir,Serkan Ünlü,Özden Kamıs¸lı,Zülal Öner 대한영상의학회 2018 Korean Journal of Radiology Vol.19 No.1
Objective: Multiple sclerosis (MS) is an inflammatory disease characterized by demyelinating plaques in the white matter. Chronic cerebrospinal venous insufficiency (CCSVI) has been proposed as a new hypothesis for the etiopathogenesis of MS disease. MS-CCSVI includes a significant decrease of cerebrospinal fluid (CSF) flow through the cerebral aqueduct secondary to an impaired venous outflow from the central nervous system. This study aimed to determine whether CSF flow dynamics are affected in MS patients and the contributions to differential diagnosis in active and chronic disease using phase-contrast magnetic resonance imaging (PC-MRI). Materials and Methods: We studied 16 MS patients with chronic plaques (group 1), 16 MS patients with active plaques-enhanced on MRI (group 2), and 16 healthy controls (group 3). Quantitatively evaluation of the CSF flow was performed from the level of the cerebral aqueduct by PC-MRI. According to heart rates, 14–30 images were obtained in a cardiac cycle. Cardiac triggering was performed prospectively using finger plethysmography. Results: No statistically significant difference was found between the groups regarding average velocity, net forward volume and the average flow (p > 0.05). Compared with the controls, group 1 and group 2, showed a higher peak velocity (5.5 ± 1.4, 4.9 ± 1.0, and 4.3 ± 1.3 cm/sec, respectively; p = 0.040), aqueductal area (5.0 ± 1.3, 4.1 ± 1.5, and 3.1 ± 1.2 mm2, respectively; p = 0.002), forward volume (0.039 ± 0.016, 0.031 ± 0.013, and 0.021 ± 0.010 mL, respectively; p = 0.002) and reverse volume (0.027 ± 0.016, 0.018 ± 0.009, and 0.012 ± 0.006 mL, respectively; p = 0.000). There were no statistical significance between the MS patients with chronic plaques and active plaques except for reverse volume. The MS patients with chronic plaques showed a significantly higher reverse volume (p = 0.000). Conclusion: This study indicated that CSF flow is affected in MS patients, contrary to the hypothesis that CCSVI-induced CSF flow decreases in MS patients. These findings may be explained by atrophy-dependent ventricular dilatation, which may occur at every stage of MS.
Perkmen Serkan,Toy Serkan,Caracuel Alfonso,Shelley Mack 서울대학교 교육연구소 2018 Asia Pacific Education Review Vol.19 No.4
The main purpose of the current study was to develop a 50-item personality scale in Turkish and Spanish based on Big Five Model of Personality and to assess its construct validity and reliability. We also compared the personality of pre-service teachers enrolled in the department of elementary education in Turkey and Spain. The participants were 555 pre-service teachers enrolled in elementary education programs at a Turkish university (280) and at a Spanish university (275). Results of confirmatory factor analysis supported the construct validity of the scale in both samples. However, 10 items had low factor loadings in their respective dimensions. Thus, they were removed from the scale. Findings regarding the comparison of Turkish and Spanish pre-service teachers revealed that they share similar personality traits; however, significant personality differences between Turkish and Spanish pre-service elementary school teachers emerged. Results of t tests on each dimension of personality revealed that the Turkish pre-service teachers’ Openness and Neuroticism scores were statistically higher than the Spanish pre-service teachers. On the other hand, the Spanish pre-service teachers’ Conscientiousness score was found to be statistically higher than that of the Turkish pre-service teachers.
Serkan Akdag,Aytac Akyol,Huseyin Altug Cakmak,Hulya Gunbatar,Muntecep Asker,Naci Babat,Aydin Rodi Tosu,Mehmet Yaman,Hasan Ali Gumrukcuoglu 대한심장학회 2015 Korean Circulation Journal Vol.45 No.6
Background and Objectives: Obstructive sleep apnea syndrome (OSAS) is associated with increased arterial stiffness and cardiovascularcomplications. The objective of this study was to assess whether the color M-mode-derived propagation velocity of the descendingthoracic aorta (aortic velocity propagation, AVP) was an echocardiographic marker for arterial stiffness in OSAS. Subjects and Methods: : The study population included 116 patients with OSAS and 90 age and gender-matched control subjects. Thepatients with OSAS were categorized according to their apnea hypopnea index (AHI) as follows: mild to moderate degree (AHI 5-30) andsevere degree (AHI≥30). Aortofemoral pulse wave velocity (PWV), carotid intima-media thickness (CIMT), brachial artery flow-mediateddilatation (FMD), and AVP were measured to assess arterial stiffness. Results: AVP and FMD were significantly decreased in patients with OSAS compared to controls (p<0.001). PWV and CIMT were increasedin the OSAS group compared to controls (p<0.001). Moreover, AVP and FMD were significantly decreased in the severe OSAS groupcompared to the mild to moderate OSAS group (p<0.001). PWV and CIMT were significantly increased in the severe group compared tothe mild to moderate group (p<0.001). AVP was significantly positively correlated with FMD (r=0.564, p<0.001). However, it was found tobe significantly inversely related to PWV (r=-0.580, p<0.001) and CIMT (r=-0.251, p<0.001). Conclusion: The measurement of AVP is a novel and practical echocardiographic method, which may be used to identify arterial stiffnessin OSAS
On the dynamics of rotating, tapered, visco-elastic beams with a heavy tip mass
Serkan Zeren,Metin Gürgöze 국제구조공학회 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.45 No.1
The present study deals with the dynamics of the flapwise (out-of-plane) vibrations of a rotating, internally damped (Kelvin-Voigt model) tapered Bernoulli-Euler beam carrying a heavy tip mass. The centroid of the tip mass is offset from the free end of the beam and is located along its extended axis. The equation of motion and the corresponding boundary conditions are derived via the Hamilton’s Principle, leading to a differential eigenvalue problem. Afterwards, this eigenvalue problem is solved by using Frobenius Method of solution in power series. The resulting characteristic equation is then solved numerically. The numerical results are tabulated for a variety of nondimensional rotational speed, tip mass, tip mass offset, mass moment of inertia, internal damping parameter, hub radius and taper ratio. These are compared with the results of a conventional finite element modeling as well, and excellent agreement is obtained.
A Note on The Weighted Q-Genocchi Numbers and Polynomials With Their Interpolation Function
( Serkan Araci ),( Mehmet Acikgoz ),( Jong Jin Seo ) 호남수학회 2012 호남수학학술지 Vol.34 No.1
Recently, T. Kim has introduced and analysed the q-Bernoulli numbers and polynomials with weight α cf.[7]: By the same motivaton, we also give some interesting properties of the q-Genocchi numbers and polynomials with weight α Also, we derive the q-extensions of zeta type functions with weight α from the Mellin transformation of this generating function which interpolates the q-Genocchi polynomials with weight α at negative integers.
A Note on the Weighted Twisted Dirichlet`s Type Q-Euler Numbers and Polynomials
( Serkan Araci ),( Nurgul Aslan ),( Jong Jin Seo ) 호남수학회 2011 호남수학학술지 Vol.33 No.3
We in this paper construct Dirichlet`s type twisted q-Euler numbers and polynomials with weight a. We give some interesting identities some relations.
Experimental tests on biaxially loaded concrete-encased composite columns
Serkan Tokgoz,Cengiz Dundar 국제구조공학회 2008 Steel and Composite Structures, An International J Vol.8 No.5
This paper reports an experimental investigation of the behaviour of concrete-encased composite columns subjected to short-term axial load and biaxial bending. In the study, six square and four L-shaped cross section of both short and slender composite column specimens were constructed and tested to examine the load-deflection behaviour and to obtain load carrying capacities. The main variables in the tests were considered as eccentricity of applied axial load, concrete compressive strength, cross section, and slenderness effect. A theoretical procedure considering the nonlinear behaviour of the materials is proposed for determination of the behaviour of eccentrically loaded short and slender composite columns. Two approaches are taken into account to describe the flexural rigidity (EI) used in the analysis of slender composite columns. Observed failure mode and experimental and theoretical load-deflection behaviour of the specimens are presented in the paper. The composite column specimens and also some composite columns available in the literature have been analysed and found to be in good agreement with the test results.
Some New Properties On The q-Genocchi Numbers and Polynomials Associated With q-Bernstein Polyomials
( Serkan Araci ),( Dilek Erdal ),( Dong Jin Kang ) 호남수학회 2011 호남수학학술지 Vol.33 No.2
The purpose of this study is to obtain some relationsbetween q-Genocchi numbers and q-Bernstein polynomials by usingfermionic p-adic q-integral on Zp.
Effect of TiO2 doping on microstructural properties of Al2O3-based single crystal ceramics
Serkan Aball 한양대학교 세라믹연구소 2011 Journal of Ceramic Processing Research Vol.12 No.1
Powders of Al2O3-TiO2 containing, 48 and 40% TiO2 by weight were formed into single crystals with a Verneuil furnace at 2088 K. Raman spectroscopy was used to determine the phase composition of the samples solidified from the Al2O3-TiO2powder. The resulting β-Al2TiO5-Al6Ti2O13, β-Al2TiO5-Al2O3 single crystals were probed with micro hardness assays, scratch test analyses, atomic force microscopy (AFM), scanning electron microscopy (SEM), thermal expansion and four-point bending tests. It was observed that the alumina-tialite single crystal retained a composition of Al2O3-TiO2 containing 60%Al2O3 by weight and displayed optimum properties.
Serkan Tokgoz,Sedat Karaahmetli,Cengiz Dundar 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.45 No.1
This paper presents experimental and analytical studies of eccentrically loaded concrete-filled double steel (CFDST) and concrete-filled double skin tube (DCFST) columns having outer stainless steel tube. Eighteen CFDST and DCFST column specimens were manufactured and tested to examine the strength and load-deflection responses. In the study, the main parameters were concrete strength, load eccentricity, cross section and slenderness. The strengths, load-deflection diagrams and failure patterns of the columns were observed. In addition, the tested CFDST and DCFST columns were analyzed to attain the capacity and load versus lateral deflection responses. The obtained theoretical results were compared with the test results. A parametric study was also performed to research the effects of the ratio of eccentricity (e/Ho) slenderness ratio (L/r), Ho/to ratio, Hi/ti ratio and the concrete compressive strength on the behavior of columns. In this work, the obtained results indicated that the ductility and capacity of columns were affected by cross section, concrete strength, steel strength, loading eccentricity and slenderness.