Araştırma Çıktıları | TR-Dizin | WoS | Scopus | PubMed
Permanent URI for this communityhttps://hdl.handle.net/11727/4806
Browse
1506 results
Search Results
Item A Local Search Heuristic with Self-tuning Parameter for Permutation Flow-Shop Scheduling Problem(2009) Dengiz, Berna; Alabas-Uslu, Cigdem; Sabuncuoglu, IhsanIn this paper, a new local search metaheuristic is proposed for the permutation flow-shop scheduling problem. In general, metaheuristics are widely used to solve this problem due to its NP-completeness. Although these heuristics are quite effective to solve the problem, they suffer from the need to optimize parameters. The proposed heuristic, named STLS, has a single self-tuning parameter which is calculated and updated dynamically based on both the response surface information of the problem field and the performance measure of the method throughout the search process. Especially, application simplicity of the algorithm is attractive for the users. Results of the experimental study show that STLS generates high quality solutions and outperforms the basic tabu search, simulated annealing, and record-to-record travel algorithms which are well-known local search based metaheuristics.Item Bilgisayar Programlama Derslerinde Öğrenme Motivasyonu Ölçeğinin Türkçe Uyarlaması: Geçerlilik ve Güvenilirlik Çalışması(Başkent Üniversitesi Eğitim Bilimleri Fakültesi, 2018) Avcı, Ummuhan; Ersoy, Halil; 0000-0001-7007-1478; 0000-0003-1598-7656Bu araştırmanın amacı Law, Lee ve Yu 2010 tarafından geliştirilen Bilgisayar Programlama Derslerinde Öğrenme Motivasyonu Ölçeği’ni Türkçe’ye uyarlamaktır. Bu amaçla geçerlik ve güvenirlik analizlerini yapmak üzere altı faktör bireysel tutum ve beklenti, zorlayıcı amaçlar, belirgin hedefler, ödül ve takdir, ceza, sosyal baskı ve rekabet ve 19 maddeden oluşan altılı Likert tipindeki ölçek, özel bir üniversitede okuyan 312 mühendislik fakültesi öğrencisine uygulanmıştır. Doğrulayıcı faktör analizi sonuçları incelendiğinde, ölçeğin altı faktörden oluştuğu doğrulanmış ve ölçeğin uyum iyiliği indislerinin yeterli düzeyde olduğu görülmüştür. Ölçeğin güvenilirliği Cronbach alfa iç tutarlılık katsayısı ile değerlendirilmiştir. Cronbach alfa katsayısının ölçeğin tamamında 0.90 olduğu ve faktörler bazında 0.71 ile 0.83 arasında değiştiği görülmüştür. Bu sonuçlar ölçeğin, bilgisayar programlama derslerinde öğrenme motivasyonunun ölçülmesinde geçerli ve güvenilir bir ölçme aracı olduğunu göstermektedir. The aim of this study is to adapt the Learning Motivation in Computer Programming Courses Scale developed by Law, Lee ve Yu 2010 to Turkish. In order to determine its validity and reliability, the scale consisting of 19 six-point Likert-type items within six factors individual attitude and expectation, challenging goals, clear direction, reward and recognition, punishment and social pressure and competition was applied to 312 engineering faculty students at a private university. When the results of the confirmatory factor analysis were examined, it was confirmed that the scale had six factors, and the goodness of fit indices are at an acceptable degree. The reliability of the scale was assessed by the Cronbach alpha internal consistency coefficient. The Cronbach’s alpha coefficiencies were found to be 0.90 for the whole scale and between 0.71 and 0.83 for the factors. These results show that scale is a valid and reliable measuring tool for learning motivation in computer programming coursesItem Yükseköğretimde Uzaktan Eğitim Uygulamalarının İncelenmesi: Türkiye Örneği(Başkent Üniversitesi Eğitim Bilimleri Fakültesi, 2017) Cabi, Emine; Ersoy, Halil; 0000-0002-7488-0309; 0000-0003-1598-7656Bu çalışma 2010 yılından 2016 yılına kadar, Türkiye yükseköğretiminde uzaktan eğitim çalışmalarının sayısal veriler ışığında incelenmesini amaçlamaktadır. 2010 ile 2016 yılları arasındaki yükseköğretimdeki öğrenci sayıları, uzaktan eğitim veren ön lisans, lisans ve yüksek lisans programlarına yerleşen öğrenci sayıları ve mevcut program sayılarının dağılımları incelenmiştir. Ön lisans ve lisans seviyesinde 20102015 arası uzaktan eğitimde öğrenim gören öğrenci sayılarına ulaşılabilirken, yüksek lisans seviyesinde sadece 2014-2015 ve 2015-2016 eğitim-öğretim dönemlerindeki program ve öğrenci sayılarına ulaşılabilmiştir. Ayrıca çalışmada genel ve programlara yerleşen öğrenci sayılarının yıllara göre değişimleri de incelenmiştir. Yapılan çalışma durum çalışması olduğundan mevcut durumu boylamsal olarak ortaya koymaktadır. Bu bağlamda, yeni açılması düşünülen uzaktan eğitim programlarının yapılandırılması çalışmalarında katkısı olabileceği düşünülmektedir. This study aims to investigate distance education implementations in higher education of Turkey from 2010 to 2016 by numeric data. For this purpose, the numbers and distribution of students at vocational schools, undergraduate and graduate level programs being executed totally in distance education method were analyzed. While it was possible to reach to the numbers of distant students at vocational schools and undergraduate levels between 2010 and 2015, only 2014-2015 and 2015-2016 years’ data were been able to obtained at graduate level. Moreover, the change in the numbers of distant students by years was investigated. Hence it is a case study, it portrays the existing situation longitudinally. In this context, it is believed that the study will contribute to the actions targeting to open new distance education programsItem Sliding hiatal hernia mimicking a left atrial mass(2019) Kocabas, Umut; Ozkalayci, Flora; Altun, Armagan; 0000-0002-3233-8263; 0000-0001-6424-9399; 32082840; ABB-5844-2020; AAG-5856-2020Item T1 Mapping by Cardiac Magnetic Resonance and Multidimensional Speckle-Tracking Strain by Echocardiography for the Detection of Acute Cellular Rejection in Cardiac Allograft Recipients(2019) Sade, Leyla Elif; Hazirolan, Tuncay; Kozan, Hatice; Ozdemir, Handan; Hayran, Mutlu; Eroglu, Serpil; Pirat, Bahar; Sezgin, Atilla; Muderrisoglu, Haldun; 29680337; X-8540-2019OBJECTIVES The aim of this study was to test the hypothesis that echocardiographic strain imaging, by tracking subtle alterations in myocardial function, and cardiac magnetic resonance T1 mapping, by quantifying tissue properties, are useful and complement each other to detect acute cellular rejection in heart transplant recipients. BACKGROUND Noninvasive alternatives to endomyocardial biopsy are highly desirable to monitor acute cellular rejection. METHODS Surveillance endomyocardial biopsies, catheterizations, and echocardiograms performed serially according to institutional protocol since transplantation were retrospectively reviewed. Sixteen-segment global longitudinal strain (GLS) and circumferential strain were measured before, during, and after the first rejection and at 2 time points for patients without rejection using Velocity Vector Imaging for the first part of the study. The second part, with cardiac magnetic resonance added to the protocol, served to validate previously derived strain cutoffs, examine the progression of strain over time, and to determine the accuracy of strain and T1 measurements to define acute cellular rejection. All tests were performed within 48 h. RESULTS Median time to first rejection (16 grade 1 rejection, 15 grade >= 2 rejection) was 3 months (interquartile range: 3 to 36 months) in 49 patients. GLS and global circumferential strain worsened significantly during grade 1 rejection and >= 2 rejection and were independent predictors of any rejection. In the second part of the study, T1 time >= 1,090 ms, extracellutar volume GLS >= 32%, GLS >-14%, and global circumferential strain >=-24% had 100% sensitivity and 100% negative predictive value to define grade >= 2 rejection with 70%, 63%, 55%, and 35% positive predictive values, respectively. The combination of GLS > 16% and T1 time >= 1,060 ms defined grade 1 rejection with 91% sensitivity and 92% negative predictive value. After successful treatment, T1 times decreased significantly. CONCLUSIONS T1 mapping and echocardiographic GLS can serve to guide endomyocardial biopsy selectively. (C) 2019 by the American College of Cardiology Foundation.Item Acute effects of exercise on choroidal thickness and ocular pulse amplitude(2019) Dervisogulları, Mehmet Serdar; Totan, Yuksel; Kulak, Ali Ender; Guler, Emre; 0000-0003-2006-2906; G-7851-2015Aim: To explore ocular changes in healthy people after exercise. Material and Method: Twenty participants underwent exercise for 15 minutes on a treadmill. Measurements of choroidal thickness, intraocular pressure (IOP), ocular pulse amplitude (OPA), and blood pressure were taken before and after exercise. Enhanced Depth, Imaging optical coherence tomography (EDI-OCT) was used to measure choroidal thickness at the fovea and at the areas 1500 mu m nasal and 1500 mu m temporal to the fovea; IOP and OPA were measured by the dynamic contour tonometer (DCT; Swiss Micro technology AG, Port, Switzerland). Blood pressure was measured concurrently with the acquisition of the scans. Results: Twenty participants (20 eyes) with a mean age of 22.65 +/- 0.98 years were measured. There was a significant increase in systolic and diastolic pressure after exercise (p<0.05). There was a significant decrease in IOP and OPA after exercise (p<0.05). There was no significant difference in the subfoveal, nasal or temporal choroidal thickness measurements after exercise (p>0.05). Discussion: In our study, there was no significant change in the thickness of the choroid after exercise. IOP and OPA significantly decreased, and systolic and diastolic blood pressure significantly increased, after exercise. This indicates an adaptation of vascular resistance due to vasoconstriction. The IOP and OPA decreases do not seem to be related with the changes in choroid thickness.Item Covering the More Visible Region by Electrochemical Copolymerization of Carbazole and Benzothiadiazole Based Donor-Acceptor Type Monomers(2019) Cansu-Ergun, Emine Gul; 0000-0002-3941-4345; I-7385-2017An electrochromic copolymer film of 2-(3,3-dihexyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepin-6-yl)-7-(3,3-dihexyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepin-8-yl)-9H-carbazole (M1) and 4,7-bis(thiophen-2-yl)benzo[c][1,2,5]thiadiazole (M2) was prepared via electrochemical technique. The copolymerization was performed with one to one monomer feed ratio. Electrochemical and optical properties of the resulting copolymer film (P3) and the homopolymer films of M1 and M2 (P1 and P2) were investigated by using cyclic voltammetry and UV-Vis spectrometry techniques, and the corresponding results were compared. Incorporation of M1 and M2 into copolymer matrix was clearly observed on the resulting cyclic voltammograms and UV-Vis spectra. P3 covered the visible regions coming from both P1 and P2, and exhibited a neutral state darker color than those of homopolymers. P3 film was found to have a multichromic behavior, appearing as brown in its neutral state while changing its color upon oxidation to dark-gray (at about 0.3 V), to blue (at about 0.6 V) and finally to grayish cyan (beyond 0.9 V), with a corresponding optical band gap of 1.65 eV.Item Numerical Solution of MHD Incompressible Convection Flow in Channels(2019) Gurbuz, Merve; Tezer-Sezgin, MunevverThe purpose of this paper is to study numerically the influence of the magnetic field, buoyancy force and viscous dissipation on the convective flow and temperature of the fluid in a square cavity, lid-driven cavity, and lid-driven cavity with an obstacle at the center. The continuity, momentum and energy equations are coupled including buoyancy and magnetic forces, and energy equation contains Joule heating and viscous dissipation. The equations are solved in terms of stream function, vorticity and temperature by using polynomial radial basis function (RBF) approximation for the inhomogeneity and particular solution. The numerical solutions are obtained for several values of Grashof number (Gr), Hartmann number (M) for fixed Prandtl number Pr = 0:71 and fixed Reynolds number Re = 100 with or without viscous dissipation. It is observed that in the absence of obstacle, viscous dissipation changes the symmetry of the isotherms, and the dominance of buoyancy force increases with an increase in Gr, whereas decreases when the intensity of magnetic field increases. The obstacle in the lid-driven cavity causes a secondary flow on its left part. The effect of moving lid is weakened on the flow and isotherms especially for large Gr when the cavity contains obstacle.Item Carpal Tunnel Syndrome: Evaluation of the Effects of Low-Level Laser Therapy With Ultrasound Strain Imaging(2019) Tezcan, Sehnaz; Ozturk, Funda Ulu; Uslu, Nihal; Nalbant, Merve; Yemisci, Oya Umit; 0000-0001-7204-3008; 29892976; ABC-5258-2020Objectives To evaluate the efficacy of low-level laser therapy on median nerve stiffness by using strain elastography in carpal tunnel syndrome (CTS). Methods This study included 37 wrists of 34 patients with mild or moderate CTS between January 2016 and August 2016. The control group comprised 17 patients (18 wrists) with CTS who were treated with wrist splinting for 3 weeks. The low-level laser therapy group included 17 patients (19 wrists) with CTS who were treated with a combination of splinting and low-level laser therapy, which was applied 5 times per week for 3 weeks. Clinical assessment scales, including the Symptom Severity Scale (SSS) and Functional Status Score (FSS), were obtained from our database. The cross-sectional area by ultrasound and strain ratio by elastography were studied. The differences in the strain ratio, cross-sectional area, SSS, and FSS between pretreatment and posttreatment periods in the groups were compared by the paired-sample t test. The correlations between changes in the strain ratio and the cross-sectional area, SSS, and FSS were analyzed by Pearson correlation coefficients. Results The control group included 13 women and 4 men, and the therapy group included 14 women and 3 men. In the therapy group, the mean values of the strain ratio, cross-sectional area, SSS, and FSS decreased significantly after laser therapy (P < .001) in contrast to the control group. No significant correlation was observed between the decreasing degree of the strain ratio and the cross-sectional area, SSS, and FSS after laser therapy. Conclusions The strain ratio and cross-sectional area of the median nerve decrease after low-level laser therapy. These changes may be related to the therapeutic effects of low-level laser therapy, such as nerve regeneration and improvement of the vascular supply.Item A Rare Case of Ectopia Cordis with Double Outlet Right Ventricle(2019) Silahlı, Musa; Gokmen, Zeynel; Gokdemir, Mahmut; 0000-0003-0944-7178Ectopiacordis is a rare anomaly. It is described that hearth is placed as partially or totally outside of thoracic cavity. Sometimes this can be accompanied liver and other organs such as intestine. Congenital heart defects are also likely to accompany to this situation. So, we present an ectopiacordis with double outlet right ventricule case who has lived for 121 days in neonatal intensive care unit.