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Article Citation - WoS: 16Citation - Scopus: 20Common Fixed Point Theorems in Cone Banach Spaces(Hacettepe Univ, Fac Sci, 2011) Abdeljawad, Thabet; Karapinar, Erdal; Tas, Kenan; MathematicsRecently, E. Karapinar (Fixed Point Theorems in Cone Banach Spaces, Fixed Point Theory Applications, Article ID 609281, 9 pages, 2009) presented some fixed point theorems for self-mappings satisfying certain contraction principles on a cone Banach space. Here we will give some generalizations of this theorem.Article The Possible Role of Kallikrein-6, 7, and Potassium Channel Proteins in Alzheimer’s Disease(Refik Saydam National Public Health Agency (RSNPHA), 2021) Bulduk,E.B.; Yildirim,F.; Yildirim,Z.Objective: Although the formation mechanism of Alzheimer’s Disease (AD) is not known with certainty, two major proteins, beta amyloid of senile plaques and tau protein of neurofibrillary tangels are responsible for AD. One of the major factors in the development of the disease is the formation of in soluble amyloid deposits, and the other one is the increased tau phosphorylation. Kallikreins (KLK’s) are a sub-family of serine proteases that play a role in the etiology of AD which is characterized by neuronal damage and loss of function.Kallikrein (KLK)-6 and KLK-7 are known to be age-related protease and are found at high levels in the central nervous system (CNS). It was previously shown to be involved in proteolysis of extracellular proteins implicated in neurodegenerative diseases such as AD. In this study, we aimed to investigate the possible role of KLK-6 and KLK-7 in the pathogenesis of AD and the relationship between potassium channel proteins. Methods: A total of 35 Alzheimer’s patients over the age 65 years, followed-up by Polatlı Duatepe Government Hospital and 35 healthy individuals (control group) admitted to the neurology clinic for routine screening with cognitive status considered normal were included in this study. After a 12-hour hunger, KLK-6 and KLK-7 were measured with inwardly rectifying potassium channel protein (KCNJ3), and two-pore potassium channel protein (KCNK9) levels were measured by the Enzyme-Linked Immuno Sorbent Assay (ELISA) in the serum of the blood samples which were taken from the antecubital vein after centrifuging for 10 minutes at 2500xg. The differences between the two groups were tested by T- test. A value of p<0.05 was considered statistically significant. Results: All the groups were matched for age and gender, but not statistically significant difference was observed (p>0.05). According to our findings, serum KLK- 6 and KLK-7 levels of Alzheimer’s group were significantly increased (p<0.05). A significant difference was not detected when the levels of serum KCNJ3 and KCNK9 of the Alzheimer’s group compared with the control group (p>0.05). Conclusion: It is thought that the failure in preventing the abnormal protein folding and accumulation leads to AD in the brain. According to the findings of the present study, a positive correlation was detected between the levels of KLK-6 and KLK-7 and AD’s pathology. © 2021. All Rights Reserved.Article Tests of Rationality in the Turkish Foreign Exchange Market(Central Bank Republic Turkey, 2014) Topbas, Neslihan; International Trade and LogisticsThe rationality of expectations has been tested in many foreign exchange markets using survey data. This study is aimed at gaining empirical insights about the expectations of market participants in the Turkish foreign exchange market. Using survey data provided by Central Bank of Turkey on the exchange rate of the Turkish lira against the US dollar, it is determined that the mean of expectations of market participants for one year and one month ahead were higher than the mean of actual depreciation. The analysis resulted in rejection of the popular test for forward exchange rate unbiasedness in predicting the future spot exchange rate. Another test of rationality has also been checked and the result has been rejection as well, which can be interpreted that the forward premium contains additional information for exchange rate forecasts.Article Citation - WoS: 2Measuring Dependence Between Electricity Consumption and Economic Indicators Via Copulas: Turkish Case(Gazi Univ, 2018) Evkaya, O. Ozan; Yozgatligil, Ceylan; Selcuk-Kestel, A. Sevtap; Kestel, A. Sevtap Selçuk; MathematicsThis paper implements copulas to identify the dependence structure between electricity consumption and its cofounding indicators. To achieve this, Turkish electricity demand, its economic and sectoral indicators are taken into account. As a first step, bivariate copulas are used to identify the best fitting copula and the degree of the dependence. Thereafter, multivariate model is established using vine copulas using highly correlated variables. The empirical results confirm the added value of the proposed approach in determining numerous tail properties. We indicate that the copulas are useful to underline, especially, the tail properties of indicators in the market for decision makers.Article Citation - WoS: 1Citation - Scopus: 1Construction of a Complex Jacobi Matrix From Two-Spectra(Hacettepe Univ, Fac Sci, 2011) Guseinov, Gusein Sh; MathematicsIn this paper we study the inverse spectral problem for two-spectra of finite order complex Jacobi matrices (tri-diagonal matrices). The problem is to reconstruct the matrix using two sets of eigenvalues, one for the original Jacobi matrix and one for the matrix obtained by deleting the first column and the first row of the Jacobi matrix. An explicit procedure of reconstruction of the matrix from the two-spectra is given.Article Citation - Scopus: 3Protective Effects of Metformin in Non-Diabetic Rats With Experimentally Induced Lower Extremity Ischemia-Reperfusion Injury(Turkish National Vascular and Endovascular Surgery Society, 2025) Küçük, Ayşegül; Dursun, Alı Dogan; Arslan, Mustafa; Sezen, Şaban Cem; Yıldırım, Alperen Kutay; Özer, Abdullah; Demirtas, HuseyinAim: Lower extremity ischemia-reperfusion (IR) injury can lead to substantial skeletal muscle damage and systemic complications, primarily driven by oxidative stress and inflammation. In addition to its well-known glucose-lowering effects, metformin possesses antioxidant and anti-inflammatory properties that may confer protection against tissue damage caused by IR. This study aims to evaluate the potential protective effects of metformin on skeletal muscle injury using a rat model of lower extremity IR.Material and Methods: A total of twenty-four male Wistar albino rats were randomly divided into four experimental groups: Control (C), Ischemia-Reperfusion (IR), IR with metformin at 4 mg/kg (IR+M4), and IR with metformin at 8 mg/kg (IR+M8). Ischemia was induced by clamping the infrarenal aorta for 45 minutes, followed by a reperfusion period of 120 minutes. In the treatment groups, metformin was administered intraperitoneally at the onset of ischemia. Gastrocnemius muscle tissues were harvested for subsequent histopathological and biochemical evaluations, including measurements of Total Antioxidant Status (TAS), Total Oxidant Status (TOS), and Oxidative Stress Index (OSI).Results: Histopathological analysis demonstrated a significant reduction in muscle atrophy, degeneration, leukocyte infiltration, and fiber fragmentation in the IR+M8 group compared to the IR group. Biochemical assessments showed that TAS levels were considerably elevated, whereas TOS and OSI levels were markedly reduced in the metformin-treated groups, with the most prominent effects observed at the higher dosage of 8 mg/kg.Conclusion: The findings indicate that metformin exerts a dose-dependent protective effect against skeletal muscle injury resulting from lower extremity ischemia-reperfusion in rats. These protective properties are likely due to metformin’s antioxidant and anti-inflammatory mechanisms, highlighting its potential therapeutic value in mitigating IR-induced tissue damage.Article Effects of Topological Structure of Project Network on Computational Cost(Golden Light Publ, 2024) Aminbakhsh, SamanUnderstanding how network complexity affects optimization algorithms is crucial for improving computational efficiency. This study investigates how variations in network complexity impact the performance of optimization algorithms. By examining networks with different serial/parallel indicator (I2) values, the research uncovers several key insights into how topology influences computational requirements. The experiments show that higher I2 values, which are closer to serial configurations, heighten the problem's complexity. This study reveals that networks with lower I2 values, which exhibit steeper time-cost curves with fewer solutions over their efficient frontiers, require significantly more CPU time, indicating that project complexity does not necessarily scale with the extend of the Pareto fronts. This contradicts the expectation that more Pareto front solutions would inherently demand greater computational resources. Lastly, the study highlights that while the number of time-cost realizations is often used to gauge project complexity, it may not be conclusive on its own and that one complexity measure can outperform another. Although it can be an effective indicator, it does not fully capture the computational challenges posed by different network topologies. This study further acknowledges the difficulty in establishing a clear link between project performance and complexity due to the multifaceted nature of the problem. The findings suggest that exploring similar problems in other contexts could provide valuable insights into understanding and managing computational complexity.Article The Turkish Adaptation, Validity, and Reliability of the Fragmented Self Inventory(Association for Clinical Psychology Research, 2025) Türkarslan, Kutlu Kağan; Akın, Zeynep GülParçalanmış Kendilik Envanteri (PKE), Heinz Kohut'un tanımladığı parçalanmış kendilik deneyimlerini incelemek için geliştirilmiş bir öz-bildirim ölçüm aracıdır. Ölçek, psikanalitik kendilik psikolojisi bağlamında parçalanmış büyüklenmecilik (PKE-PB) ve parçalanmış idealleştirme (PKE-Pİ) olmak üzere iki kendilik eksenindeki deneyimlere odaklanmaktadır. Bu çalışmanın amacı PKE’yi Türkçe’ ye uyarlamak ve psikometrik özelliklerini Türkçe konuşan bir örneklemde değerlendirmektir. Çalışmanın verileri 495 katılımcıdan toplanmıştır (kadın = %67.88, Ort.yaş = 33.86, SS = 12.87). PKE'nin iki faktörlü yapısını doğrulamak için doğrulayıcı faktör analizi gerçekleştirilmiştir. Ölçeğin yakınsak geçerliği, PKE-PB ve PKE-Pİ puanlarının; özsaygı, patolojik narsisizm, öz-denetim, disiplin, duygu düzenleme güçlüğü, hayat anlam ve amacı, depresyon, anksiyete ve stres değişkenleri ile ilişkisine bakılarak değerlendirilmiştir. Ölçeğin güvenirliği ise iç tutarlılık katsayıları ve test-tekrar test sınıf içi korelasyonları ile incelenmiştir. Doğrulayıcı faktör analizinin sonuçları PKE'nin Türkçe formunun iki faktörlü yapısını desteklemektedir. Parçalanmış büyüklenmecilik ekseninde daha yüksek puanların, düşük benlik saygısı ve yüksek patolojik narsisizm belirtileri ile; parçalanmış idealleştirmede daha yüksek puanların ise düşük öz-denetim, düşük disiplin, yüksek duygu düzenleme zorlukları ve hayatta anlam ve amaç bulma-da daha fazla güçlük çekme ile ilişkili olması, PKE’nin yakınsak geçerliğini desteklemektedir. PKE-PB ve PKE-Pİ alt ölçeklerinin, tatmin edici iç tutarlılık gösterdiği (McDonald'ın ω = .77 ve .86) ve dört haftalık test-tekrar test güvenirliğine (SKK = .78 ve .81) sahip olduğu görülmüştür. Parçalanmış büyüklenmecilik ve parçalanmış idealleştirmenin depresyon, anksiyete ve stresi yordadığı yol analizinde, parçalanmış büyüklenmeciliğin anksiyete ve stresi, parçalanmış idealleştirmenin ise depresyon, anksiyete ve stresi anlamlı şekilde yordadığı bulunmuştur. Bu çalışmanın bulguları, PKE'nin Türkçe formunun parçalanmış büyüklenmecilik ve parçalanmış idealleştirme deneyimlerini ölçmekte kullanılabileceğine işaret etmektedir.Article Citation - WoS: 1Citation - Scopus: 1ON THE DERIVATION OF EXPLICIT FORMULAE FOR SOLUTIONS OF THE WAVE EQUATION IN HYPERBOLIC SPACE(Hacettepe Univ, Fac Sci, 2013) Guseinov, Gusein Sh.We offer a new approach to solving the initial value problem for the wave equation in hyperbolic space in arbitrary dimensions. Our approach is based on the spectral analysis of the Laplace-Beltrami operator in hyperbolic space and some structural formulae for rapidly decreasing functions of this operator.Article Citation - Scopus: 9The Effects of Eryngium Campestre Extracts on Glutathione-S Glutathione Peroxidase and Catalase Enzyme Activities;(Turkish Pharmacists Association, 2014) Güneş,M.G.; İşgör,B.S.; İşgör,Y.G.; Shomali Moghaddam,N.; Geven,F.; Yildirim,Ö.; Moghaddam, Naznoosh ShomalıEryngium campestre L. (Apiaceae) are known in Turkish folk medicine as ‘Bogadikeni’ and wildly distributed in all parts of Turkey. Infusion of different parts of this species are well known as diuretic, appetizer and stimulant. In the present study, methanol extracts from flowers and leaves of E. campestre were evaluated for their potential medicinal value in terms of biological targets participate in antioxidant defense such as glutathione-S-transferase (GST), glutathione peroxidase (GPx) and catalase (CAT). Results obtained show that the methanol extract of flowers were found to have higher amount of phenolic and flavonoid contents than the leaves. The evaluation of extracts against biological target revealed that, the maximum GST enzymes inhibition activities was observed with methanol extract from flowers of E. campestre with IC50 value of 363 ng/mL. In this study, none of the extracts evaluated were shown any reasonable GPx and CAT inhibition. © 2014, Turkish Pharmacists Association. All rights reserved.
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