On the Equivalance of Some Fixed Point Iterations

Ozdemir, Murat,Akbulut, Sezgin Department of Mathematics 2006 Kyungpook mathematical journal Vol.46 No.2

In this paper, we have shown that the convergence of one-step, two-step and three-step iterations is equivalent, which are known as Mann, Ishikawa and Noor iteration procedures, for a special class of Lipschitzian operators defined in a closed, convex subset of an arbitrary Banach space.

Quantitative evaluation of alveolar cortical bone density in adults with different vertical facial typesusing cone-beam computed tomography

Fulya Ozdemir,Murat Tozlu,Derya Germec Cakan 대한치과교정학회 2014 대한치과교정학회지 Vol.44 No.1

Objective: The purpose of this study was to quantitatively evaluate the cortical bone densities of the maxillary and mandibular alveolar processes in adults with different vertical facial types using cone-beam computed tomography (CBCT) images. Methods: CBCT images (n = 142) of adult patients (20?45 years) were classified into hypodivergent, normodivergent, and hyperdivergent groups on the basis of linear and angular S-N/Go-Me measurements. The cortical bone densities (in Hounsfield units) at maxillary and mandibular interdental sites from the distal aspect of the canine to the mesial aspect of the second molar were measured on the images. Results: On the maxillary buccal side, female subjects in the hyperdivergent group showed significantly decreased bone density, while in the posterior region, male subjects in the hyperdivergent group displayed significantly decreased bone density when compared with corresponding subjects in the other groups (p<0.001). Furthermore, the subjects in the hyperdivergent group had significantly lower bone densities on the mandibular buccal side than hypodivergent subjects. The maxillary palatal bone density did not differ significantly among groups, but female subjects showed significantly denser palatal cortical bone. No significant difference in bone density was found between the palatal and buccal sides in the maxillary premolar region. Overall, the palatal cortical bone was denser anteriorly and buccal cortical bone was denser posteriorly. Conclusion: Adults with the hyperdivergent facial type tend to have less-dense buccal cortical bone in the maxillary and mandibular alveolar processes. Clinicians should be aware of the variability of cortical bone densities at mini-implant placement sites.

The Effect of Hepatitis C Virus Infection on Insulin Resistance in Chronic Haemodialysis Patients

Ali Ozdemir,Berrin Yalinbas,Umut Selamet,Meltem Eres,Funda Turkmen,Fatma Kumbasar,Berna Murat,A. Tayfun Keskin,Yildiz Barut 연세대학교의과대학 2007 Yonsei medical journal Vol.48 No.2

Flexural Behavior of Laminated Wood Beams Strengthened with Novel Hybrid Composite Systems: An Experimental Study

( Mehmet Faruk Ozdemir ),( Muslum Murat Maras ),( Hasan Basri Yurtseven ) 한국목재공학회 2023 목재공학 Vol.51 No.6

Wooden structures are widely used, particularly in earthquake zones, owing to their light weight, ease of application, and resistance to the external environment. In this study, we aimed to improve the mechanical properties of laminated timber beams using novel hybrid systems [carbon-fiber-reinforced polymer (CFRP) and wire rope]. Within the scope of this study, it is expected that using wood, which is an environmentally friendly and sustainable building element, will be more economical and safe than the reinforced concrete and steel elements currently used to pass through wide openings. The structural behavior of the hybrid-reinforced laminated timber beams was determined under the loading system. The experimental findings showed that the highest increase in the values of laminated beams reinforced with steel ropes was obtained with the 2N reinforcement, with a maximum load of 38 kN and a displacement of 137 mm. Thus, a load increase of 168% and displacement increase of 275% compared with the reference sample were obtained. Compared with the reference sample, a load increase of 92% and a displacement increase of 14% were obtained. Carbon fabrics placed between the layers with fiber-reinforced polymer (FRP) prevented crack development and provided significant interlayer connections. Consequently, the fabrics placed between the laminated wooden beams with the innovative reinforcement system will not disrupt the aesthetics or reduce the effect of earthquake forces, and significant reductions can be achieved in these sections.

mRNA Expression Level of Interleukin Genes in the Determining Phases of Behcet`s Disease

( Serpil Taheri ),( Murat Borlu ),( Cem Evereklioglu ),( Sevda Yesim Ozdemir ),( Yusuf Ozkul ) 대한피부과학회 2015 Annals of Dermatology Vol.27 No.3

Background: Behcet``s disease (BD), first described in 1937 as a triadic complex of symptoms (oral aphthae, genital ulcers, and hypopyon uveitis), is a chronic, relapsing, multisystemic idiopathic inflammatory disease. Objective: The objective of this study was to investigate the usability of messenger RNA (mRNA) expression of cytokine genes for following up patients with BD and also assess polymorphisms in these genes as to how they influence mRNA expression. Methods: This study investigated the role of the IL1A -889(C/T), IL1B - 511(C/T), and IL2 -330(T/G) polymorphisms by polymerase chain reaction (PCR)-restriction fragment length polymorphisms and the expression levels of the genes by real- time PCR in BD. Results: The frequency of the IL2 -330 G allele was found to be significantly higher in patients with BD. A decreased level of IL1A gene expression was found in the patient group with clinically active BD compared to controls. Increased IL1B gene expression levels werefound in patient groups with active, inactive, or ocular BD (p<0.001). IL2 gene expression level manifested no significant change compared to controls in the patient group with clinically active BD; it increased in the groups with clinically inactive BD or ocular involvement. Conclusion: IL1A, IL1B, and IL2 gene expression, and IL2 promoter polymorphisms, may be valuable markers for predicting risk in the development of BD. We believe that the results reveal the importance of achieving a better understanding of BD and the prospects of developing future therapeutic strategies. (Ann Dermatol 27(3) 291∼297, 2015)

The relationship of organizational corruption with organizational culture, attitude towards work and work ethics: a search on Turkish high school teachers

Ali Balcı,Murat Ozdemir,Cigdem Apaydın,Fatmanur Ozen 서울대학교 교육연구소 2012 Asia Pacific Education Review Vol.13 No.1

The aim of this study is to analyse organizational corruption and to determine its level of relation to attitude towards work, work ethics and organizational culture. The data in study have been collected from 441 public high school teachers employed in the central districts of Ankara in the school year of 2008-2009. Data have been collected through 'Scale for Organizational Corruption', 'Scale for Attitude towards Work', 'Scale for Work Ethics' and 'Scale for Organizational Culture', all of which were developed by the researchers in this study. Correlation and regression analysis techniques have been used in analysing the data. It is concluded from the study that there is a significant, though at an average level, relation between organizational corruption, organizational culture and work ethics and that there is a negative significant relation, though at a low level, between organizational corruption and attitude towards work. It is also concluded that the variables for attitude towards work, work ethics and organizational culture explain 38% of the variation in organizational corruption.

Routine calcitonin measurement in nodular thyroid disease management: is it worthwhile?

Yigit Turk,Ozer Makay,Murat Ozdemir,Gozde Ertunc,Batuhan Demir,Gokhan Icoz,Mahir Akyildiz,Mustafa Yilmaz 대한외과학회 2017 Annals of Surgical Treatment and Research(ASRT) Vol.92 No.4

Purpose: To evaluate the diagnostic accuracy of routine calcitonin measurement in patients with nodular thyroid disease. Methods: Consecutive patients with nodular thyroid disease (n = 640) were studied. Serum calcitonin levels were measured under basal conditions, and when basal values were between 10–100 pg/mL, testing was repeated after pentagastrin (PG) stimulation. Patients with previously diagnosed or familial medullary thyroid cancer (MTC) were excluded. Patients were operated on when basal or stimulated calcitonin >100 pg/mL or when other surgical indications were present. Results: Four cases of MTC were identified. MTC was diagnosed in 75% of patients with basal calcitonin >100 pg/mL. One out of 11 patients with basal calcitonin between 10–100 pg/mL was diagnosed with MTC. PG stimulation resulted in elevation in 4 cases, where 1 case was diagnosed with MTC. Positive predictive value for basal calcitonin levels in the preoperative diagnosis of MTC was 5% for values between 10–100 pg/mL and 100% for values >100 pg/mL. Possible reasons for false positivity were papillary thyroid cancer in 17%, renal insufficiency in 8.3%, Hashimoto thyroiditis in 17% and β-blocker use in 33%. Positive predictive value for the PG test (>100 pg/mL) was 25% in the entire series. The cost of adding calcitonin measurement (±PG stimulation) to the preoperative work-up, resulted in €912.68 per MTC patient to detect the disease. Conclusion: Basal calcitonin measurement together with PG stimulation in cases of basal calcitonin >10 pg/mL detects MTC in 0.62% of patients with nodular thyroid disease.

Long-Term Treatment Results in Soft Tissue Sarcomas of the Thoracic Wall Treated with Pre-or-Postoperative Radiotherapy - a Single Institution Experience

Oksuz, Didem Colpan,Ozdemir, Sevim,Kaydihan, Nuri,Dervisoglu, Sergulen,Hiz, Murat,Tuzun, Hasan,Mandel, Nil Molinas,Koca, Sedat,Dincbas, Fazilet Oner Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.22

Objective: To evaluate the long term results among patients with soft tissue sarcoma of the thoracic wall. Materials and Methods: Twenty-six patients who were treated with pre-or postoperative radiotherapy between December 1980-December 2007, with a diagnosis of soft tissue sarcoma of the thoracic wall were retrospectively evaluated. Results: The median age was 44 years (14-85 years) and 15 of them were male. A total of 50% of patients were grade 3. The most common histologic type of tumor was undifferentiated pleomorphic sarcoma (26.9%). Tumor size varied between 2-25 cm (median 6.5 cm). Seventeen of the cases had marginal and 9 had wide local resection. Four cases received preoperative radiotherapy and 22 postoperative radiotherapy. Six of the patients with large and high grade tumors received chemotherapy. Median follow-up time was 82 months (9-309 months). Local recurrence and metastasis was detected in 34.6% and 42.3% of patients, respectively. Five-year local control (LC), disease-free survival (DFS), overall survival (OS), and disease-specific survival (DSS) were 62%, 38%, 69%, and 76% respectively. On univariate analysis, the patients with positive surgical margins had a markedly lower 5-year LC rate than patients with negative surgical margin, but the difference was not significant (43% vs 78%, p=0.1). Five-year DFS (66% vs 17%) and DSS (92% vs 60%) rates were significantly worse for the patients who had high grade tumors (p=0.01, p=0.008 respectively). Conclusions: Tumor grade and surgical margin are essential parameters for determining the prognosis of thoracic wall soft tissue sarcoma both in our series and the literature.

Analyzing the mechano-bactericidal effect of nano-patterned surfaces by finite element method and verification with artificial neural networks

Ecren Uzun Yaylaci,Murat Yaylaci,Mehmet Emin Ozdemir,Merve Terzi,Sevval Ozturk Techno-Press 2023 Advances in nano research Vol.15 No.2

The study investigated the effect of geometric structures of nano-patterned surfaces, such as peak sharpness, height, width, aspect ratio, and spacing, on mechano-bactericidal properties. Here, in silico models were developed to explain surface interactions with Escherichia coli. Numerical solutions were performed based on the finite element method and verified by the artificial neural network method. An E. coli cell adhered to the nano surface formed elastic and creep deformation models, and the cells' maximum deformation, maximum stress, and maximum strain were calculated. The results determined that the increase in peak sharpness, aspect ratio, and spacing values increased the maximum deformation, maximum stress, and maximum strain on E. coli cell. In addition, the results showed that FEM and ANN methods were in good agreement with each other. This study proved that the geometrical structures of nano-patterned surfaces have an important role in the mechano-bactericidal effect.

Analysis of the mechano-bactericidal effects of nanopatterned surfaces on implant-derived bacteria using the FEM

Ecren Uzun Yaylaci,Mehmet Emin Ozdemir,Yilmaz Guvercin,Sevval Ozturk,Murat Yaylaci Techno-Press 2023 Advances in nano research Vol.15 No.6

The killing of bacteria by mechanical forces on nanopatterned surfaces has been defined as a mechano-bactericidal effect. Inspired by nature, this method is a new-generation technology that does not cause toxic effects and antibiotic resistance. This study aimed to simulate the mechano-bactericidal effect of nanopatterned surfaces' geometric parameters and material properties against three implant-derived bacterial species. Here, in silico models were developed to explain the interactions between the bacterial cell and the nanopatterned surface. Numerical solutions were performed based on the finite element method. Elastic and creep deformation models of bacterial cells were created. Maximum deformation, maximum stress, maximum strain, as well as mortality of the cells were calculated. The results showed that increasing the peak sharpness and decreasing the width of the nanopatterns increased the maximum deformation, stress, and strain in the walls of the three bacterial cells. The increase in spacing between nanopatterns increased the maximum deformation, stress, and strain in E. coli and P. aeruginosa cell walls it decreased in S. aureus. The decrease in width with the increase in sharpness and spacing increased the mortality of E. coli and P. aeruginosa cells, the same values did not cause mortality in S. aureus cells. In addition, it was determined that using different materials for nanopatterns did not cause a significant change in stress, strain, and deformation. This study will accelerate and promote the production of more efficient mechano-bactericidal implant surfaces by modeling the geometric structures and material properties of nanopatterned surfaces together.