1422 results
Search Results
Now showing 1 - 10 of 1422
Article Citation - WoS: 14Citation - Scopus: 25On Coupled Fixed Point Theorems on Partially Ordered g-metric Spaces(Springeropen, 2012) Karapinar, Erdal; Kaymakcalan, Billur; Tas, KenanIn this manuscript, we extend, generalize and enrich some recent coupled fixed point theorems in the framework of partially ordered G-metric spaces in a way that is essentially more natural.Article Citation - WoS: 4Citation - Scopus: 4The Effect of Cerium Oxide (ceo2) on Ischemia-Reperfusion Injury in Skeletal Muscle in Mice With Streptozocin-Induced Diabetes(Mdpi, 2024) Ozer, Abdullah; Sengel, Necmiye; Kucuk, Ayseguel; Yigman, Zeynep; Ozdemir, Cagri; Kilic, Yigit; Arslan, MustafaObjective: Lower extremity ischemia-reperfusion injury (IRI) may occur with trauma-related vascular injury and various vascular diseases, during the use of a tourniquet, in temporary clamping of the aorta in aortic surgery, or following acute or bilateral acute femoral artery occlusion. Mitochondrial dysfunction and increased basal oxidative stress in diabetes may cause an increase in the effects of increased reactive oxygen species (ROS) and mitochondrial dysfunction due to IRI. It is of great importance to examine therapeutic approaches that can minimize the effects of IRI, especially for patient groups under chronic oxidative stress such as DM. Cerium oxide (CeO2) nanoparticles mimic antioxidant enzymes and act as a catalyst that scavenges ROS. In this study, it was aimed to investigate whether CeO2 has protective effects on skeletal muscles in lower extremity IRI in mice with streptozocin-induced diabetes. Methods: A total of 38 Swiss albino mice were divided into six groups as follows: control group (group C, n = 6), diabetes group (group D, n = 8), diabetes-CeO2 (group DCO, n = 8), diabetes-ischemia/reperfusion (group DIR, n = 8), and diabetes-ischemia/reperfusion-CeO2 (group DIRCO, n = 8). The DCO and DIRCO groups were given doses of CeO2 of 0.5 mg/kg intraperitoneally 30 min before the IR procedure. A 120 min ischemia-120 min reperfusion period with 100% O-2 was performed. At the end of the reperfusion period, muscle tissues were removed for histopathological and biochemical examinations. Results: Total antioxidant status (TAS) levels were found to be significantly lower in group DIR compared with group D (p = 0.047 and p = 0.022, respectively). In group DIRCO, total oxidant status (TOS) levels were found to be significantly higher than in group DIR (p < 0.001). The oxidative stress index (OSI) was found to be significantly lower in group DIR compared with group DCO (p < 0.001). Paraoxanase (PON) enzyme activity was found to be significantly increased in group DIR compared with group DCO (p < 0.001). The disorganization and degeneration score for muscle cells, inflammatory cell infiltration score, and total injury score in group DIRCO were found to be significantly lower than in group DIR (p = 0.002, p = 0.034, and p = 0.001, respectively). Conclusions: Our results confirm that CeO2, with its antioxidative properties, reduces skeletal muscle damage in lower extremity IRI in diabetic mice.Article Citation - WoS: 17Citation - Scopus: 17Productivity and Growth in an Unstable Emerging Market Economy: the Case of Turkey, 1960-2004(Routledge Journals, Taylor & Francis Ltd, 2009) Ismihan, Mustafa; Metin-Ozcan, KivilcimThis paper explores sources of growth in the Turkish economy by performing growth accounting exercises over the 1960-2004 period and relevant subperiods. It also analyzes the role of a number of important policy-related factors, such as infrastructure investment, macroeconomic instability, and imports, on total factor productivity (TFP) by performing cointegration and impulse response analyses. The results suggest that both TFP and capital accumulation were crucial sources of growth during the sample period. Nevertheless, TFP growth displayed enormous variation from 1960 to 2004. The descriptive and empirical evidence suggests that TFP is positively affected by imports and public infrastructure investment and negatively affected by macroeconomic instability.Article Citation - WoS: 22Citation - Scopus: 21Principal and Nonprincipal Solutions of Impulsive Differential Equations With Applications(Elsevier Science inc, 2010) Ozbekler, A.; Zafer, A.We introduce the concept of principal and nonprincipal solutions for second order differential equations having fixed moments of impulse actions is obtained. The arguments are based on Polya and Trench factorizations as in non-impulsive differential equations, so we first establish these factorizations. Making use of the existence of nonprincipal solutions we also establish new oscillation criteria for nonhomogeneous impulsive differential equations. Examples are provided with numerical simulations to illustrate the relevance of the results. (C) 2010 Elsevier Inc. All rights reserved.Article Citation - WoS: 35Citation - Scopus: 35Friction Stir Processing of Dual Phase Steel: Microstructural Evolution and Mechanical Properties(Elsevier Science inc, 2019) Aktarer, S. M.; Kucukomeroglu, T.; Davut, K.The influence of friction stir processing (FSP) on the microstructure and mechanical properties of a DP 600 steel has been studied. The microstructure evolution during the FSP has been characterized using electron back scatter diffraction (EBSD) technique and scanning and transmission electron microscopes. Standard tension and hardness tests were used to characterize the mechanical properties. The results show that the FSP produced a refined microstructure composed of ferrite, bainite, martensite, and tempered martensite which in turn increased the hardness and strength magnitudes by a factor of 1.5. The initially 2.83 mu m average grain size of ferrite has decreased to 0.79 mu m in the pin effected zone of (PE-SZ-I) of the processed region. Both EBSD and TEM observations showed regions with high dislocation density and sub-structures region in the processed zone. The grain size became coarser, the density of both dislocations and low-angle grain boundaries decrease, away from the processed zone. Moreover, phase fractions and hardness values were predicted using CALPHAD thermodynamic based software based on commercial material properties. Although the prediction does not take into consideration the influence of severe plastic deformation, the results were within 10% uncertainties of the experimental findings. The present study demonstrates that an ultra-fine grained structure can be obtained through the thickness of a 1.5 mm thick D P600 steel sheet via FSP. FSP can produce a range of different hardness and strength values; which can also be predicted successfully by inputting the composition and local temperatures reached during the FSP.Article Citation - WoS: 11Citation - Scopus: 16Therapeutic Efficacy of Boric Acid Treatment on Brain Tissue and Cognitive Functions in Rats With Experimental Alzheimer's Disease(Dove Medical Press Ltd, 2023) Ozdemir, Cagri; Arslan, Mustafa; Kucuk, Aysegul; Yigman, Zeynep; Dursun, Ali DoganIntroduction: Oxidative stress has an important role in the pathophysiology of Alzheimer's disease (AD), the most common type of dementia. Boric acid (BA) contributes significantly to the protection of the brain by reducing lipid peroxidation and supporting antioxidant defense. We aimed to evaluate the therapeutic potential of BA treatment in AD rats. Materials and Methods: Four groups were formed as Control (C), Alzheimer's (A), Alzheimer's + Boric acid (ABA), Boric acid (BA). Intracerebroventricular injection of Streptozotocin (STZ) was preferred to create an AD. After 4 weeks, BA was applied 3 times every other day. The Radial Arm Maze Test (RAMT) was used to evaluate memory and learning abilities. Biochemical and histopathological evaluations were made in the hippocampus. Results: Initial RAMT inlet/outlet (I/O) numbers were similar. Two weeks after STZ injection, I/O numbers decreased in group A and ABA compared to group C and BA (p<0.05). After the second BA application, I/O numbers increased in the ABA group compared to the A group (p<0.05). In group A, PON-1, TOS and OSI levels were higher and TAS levels were lower than in groups BA and C. After BA treatment, PON-1 and OSI levels were lower in the ABA group than in the A group (p<0.05). Although there was an increase in TAS value and a decrease in TOS, this did not make a statistical difference. The thickness of the pyramidal cell in CA1 and the granular cell layers in the dentate gyrus, and the number of intact and degenerated neurons in the pyramidal cell layer were similar between the groups. Discussion: Significant improvement in learning and memory abilities after BA application is promising for AD. Conclusion: These results show that BA application positively affects learning and memory abilities, and reduces oxidative stress. More extensive studies are required to evaluate histopathological efficacy.Article Citation - WoS: 69Citation - Scopus: 71An Approach To Best Proximity Points Results Via Simulation Functions(Springer Basel Ag, 2017) Karapinar, Erdal; Khojasteh, FarshidIn this paper, we investigate of the existence of the best proximity points of certain mapping defined via simulation functions in the frame of complete metric spaces. We consider the uniqueness criteria for such mappings. The obtained results unify a number of the existing results on the topic in the literature.Article Citation - WoS: 5Citation - Scopus: 6High Persistence and Nonlinear Behavior in Financial Variables: a More Powerful Unit Root Testing in the Estar Framework(Mdpi, 2021) Omay, Tolga; Corakci, Aysegul; Hasdemir, EsraIn this study, we consider the hybrid nonlinear features of the Exponential Smooth Transition Autoregressive-Fractional Fourier Function (ESTAR-FFF) form unit root test. As is well known, when developing a unit root test for the ESTAR model, linearization is performed by the Taylor approximation, and thereby the nuisance parameter problem is eliminated. Although this linearization process leads to a certain amount of information loss in the unit root testing equation, it also causes the resulting test to be more accessible and consistent. The method that we propose here contributes to the literature in three important ways. First, it reduces the information loss that arises due to the Taylor expansion. Second, the research to date has tended to misinterpret the Fourier function used with the Kapetanios, Shin and Snell (2003) (KSS) unit root test and considers it to capture multiple smooth transition structural breaks. The simulation studies that we carry out in this study clearly show that the Fourier function only restores the Taylor residuals of the ESTAR type function rather than accounting forthe smooth structural break. Third, the new nonlinear unit root test developed in this paper has very strong power in the highly persistent near unit root environment that the financial data exhibit. The application of the Kapetanios Shin Snell- Fractional Fourier (KSS-FF) test to ex-post real interest rates data of 11 OECD countries for country-specific sample periods shows that the new test catches nonlinear stationarity in many more countries than the KSS test itself.Article Effects of Pomegranate Seed Oil on Lower Extremity Ischemia-Reperfusion Damage: Insights into Oxidative Stress, Inflammation, and Cell Death(MDPI, 2025) Bozok, Ummu Gulsen; Ergorun, Aydan Iremnur; Kucuk, Aysegul; Yigman, Zeynep; Dursun, Ali Dogan; Arslan, MustafaAim: This study sought to clarify the therapeutic benefits and mechanisms of action of pomegranate seed oil (PSO) in instances of ischemia–reperfusion (IR) damage in the lower extremities. Materials and Methods: The sample size was determined, then 32 rats were randomly allocated to four groups: Control (C), ischemia–reperfusion (IR), low-dose PSO (IR + LD, 0.15 mL/kg), and high-dose PSO (IR + HD, 0.30 mL/kg). The ischemia model in the IR group was established by occluding the infrarenal aorta for 120 min. Prior to reperfusion, PSO was delivered to the IR + LD and IR + HD groups at doses of 0.15 mL/kg and 0.30 mL/kg, respectively, followed by a 120 min reperfusion period. Subsequently, blood and tissue specimens were obtained. Statistical investigation was executed utilizing Statistical Package for the Social Sciences version 20.0 (SPSS, IBM Corp., Armonk, NY, USA). Results: Biochemical tests revealed significant variations in total antioxidant level (TAS), total oxidant level (TOS), and the oxidative stress index (OSI) across the groups (p < 0.0001). The IR group had elevated TOS and OSI levels, whereas PSO therapy resulted in a reduction in these values (p < 0.05). As opposed to the IR group, TASs were higher in the PSO-treated groups. Histopathological analysis demonstrated muscle fiber degeneration, interstitial edema, and the infiltration of cells associated with inflammation in the IR group, with analogous results noted in the PSO treatment groups. Immunohistochemical analysis revealed that the expressions of Tumor Necrosis Factor-alpha (TNF-α), Nuclear Factor kappa B (NF-κB), cytochrome C (CYT C), and caspase 3 (CASP3) were elevated in the IR group, while PSO treatment diminished these markers and attenuated inflammation and apoptosis (p < 0.05). The findings demonstrate that PSO has a dose-dependent impact on IR injury. Discussion: This research indicates that PSO has significant protective benefits against IR injury in the lower extremities. PSO mitigated tissue damage and maintained mitochondrial integrity by addressing oxidative stress, inflammation, and apoptotic pathways. Particularly, high-dose PSO yielded more substantial enhancements in these processes and exhibited outcomes most comparable to the control group in biochemical, histological, and immunohistochemical investigations. These findings underscore the potential of PSO as an efficacious natural treatment agent for IR injury. Nevertheless, additional research is required to articulate this definitively.Article Citation - WoS: 70Citation - Scopus: 86Cost, Benefits and Quality of Software Development Documentation: a Systematic Mapping(Elsevier Science inc, 2015) Zhi, Junji; Garousi-Yusifoglu, Vahid; Sun, Bo; Garousi, Golara; Shahnewaz, Shawn; Ruhe, GuentherContext: Software documentation is an integral part of any software development process. Researchers and practitioners have expressed concerns about costs, benefits and quality of software documentation in practice. On the one hand, there is a lack of a comprehensive model to evaluate the quality of documentation. On the other hand, researchers and practitioners need to assess whether documentation cost outweighs its benefit. Objectives: In this study, we aim to summarize the existing literature and provide an overview of the field of software documentation cost, benefit and quality. Method: We use the systematic-mapping methodology to map the existing body of knowledge related to software documentation cost, benefit and quality. To achieve our objectives, 11 Research Questions (RQ) are raised. The primary papers are carefully selected. After applying the inclusion and exclusion criteria, our study pool included a set of 69 papers from 1971 to 2011. A systematic map is developed and refined iteratively. Results: We present the results of a systematic mapping covering different research aspects related to software documentation cost, benefit and quality (RQ1-11). Key findings include: (1) validation research papers are dominating (27 papers), followed by solution proposals (21 papers). (2) Most papers (61 out of 69) do not mention the development life-cycle model explicitly. Agile development is only mentioned in 6 papers. (3) Most papers include only one "System under Study" (SUS) which is mostly academic prototype. The average number of participants in survey-based papers is 106, the highest one having approximately 1000 participants. (4) In terms of focus of papers, 50 papers focused on documentation quality, followed by 37 papers on benefit, and 12 papers on documentation cost. (5) The quality attributes of documentation that appear in most papers are, in order: completeness, consistency and accessibility. Additionally, improved meta-models for documentation cost, benefit and quality are also presented. Furthermore, we have created an online paper repository of the primary papers analyzed and mapped during this study. Conclusion: Our study results show that this research area is emerging but far from mature. Firstly, documentation cost aspect seems to have been neglected in the existing literature and there are no systematic methods or models to measure cost. Also, despite a substantial number of solutions proposed during the last 40 years, more and stronger empirical evidences are still needed to enhance our understanding of this area. In particular, what we expect includes (1) more validation or evaluation studies; (2) studies involving large-scale development projects, or from large number of study participants of various organizations; (3) more industry-academia collaborations; (4) more estimation models or methods to assess documentation quality, benefit and, especially, cost. (C) 2014 Elsevier Inc. All rights reserved.
