TR-Dizin

Permanent URI for this collectionhttps://hdl.handle.net/20.500.14411/21

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An Adaptive Element Division Algorithm for Accurate Evaluation of Singular and Near Singular Integrals in 3d
(Tubitak Scientific & Technological Research Council Turkey, 2021) Bayindir, Hakan; Baranoglu, Besim; Yazici, Ali
An adaptive algorithm for evaluation of singular and near singular integrals in 3D is presented. The algorithm is based on successive adaptive/selective subdivisions of the element until a prescribed error criteria is met. For evaluating the integrals in each subdivision, Gauss quadrature is applied. The method is computationally simple, memory efficient and can be applied for both triangular and quadrilateral elements, including the elements with nonplanar and/or curved surfaces. To assess the method, several examples are discussed. It has shown that the algorithm performs well for singular and near-singular integral examples presented in the paper and evaluates the integrals with very high accuracy.
Citation - WoS: 1
Citation - Scopus: 1
Anticipatory Effect of Execution on Observation: an Approach Using Exopinch Finger Robot
(Tubitak Scientific & Technological Research Council Turkey, 2019) Arıkan, Kutluk Bilge; Zadeh, Hassan Gol Mohammad; Turgut, Ali Emre; Zinnuroğlu, Murat; Bayer, Gözde; Günendi, Zafer; Cengiz, Bülent
Background/aim: This study aims to explore the mirror neuron system (MNS) involvement using mu (8–12 Hz)/beta (15–25 Hz) bandsuppression in an action observation-execution paradigm.Materials and methods: Electrophysiological (EEG) data from 16 electrodes were recorded while 8 participants observed video clips ofa hand squeezing a spring. Specifically, the effect of anticipated execution on observation was studied. For this purpose, a fully actuatedfinger exoskeleton robot was utilized to synchronize observation and execution and to control the execution condition for the participants. Anticipatory effect was created with a randomized robot accompany session.Results: The results showed that the observational condition (with or without anticipation) interacted with hemisphere at central channels near somatosensory cortex. Additionally, we explored the response of MNS on the kinetics features of visual stimuli (hard or softspring).Conclusion: The results showed an interaction effect of kinetics features and hemisphere at frontal channels corresponding nearly tothe ventral premotor cortex area of the brain. The activation of mirror neurons in this area plays a crucial role in observational learning.Based on our results, we propose that specific type of visual stimuli can be combined with the functional abilities of the MNS in the action observation based treatment of hand motor dysfunction of stroke patients to have a positive additional impact.
Citation - Scopus: 2
An Approach for Performance Prediction of Saturated Brushed Permanent Magnet\rdirect Current (dc) Motor From Physical Dimensions
(Tubitak Scientific & Technological Research Council Turkey, 2022) Asl, Rasul Tarvirdilu; Zeinali, Reza; Ertan, Hulusi Bulent
An analytical approach for performance prediction of saturated brushed permanent magnet direct current\r(DC) motors is proposed in this paper. In case of a heavy saturation in the stator back core of electrical machines, some\rflux completes its path through the surrounding air, and the conventional equivalent circuit cannot be used anymore.\rThis issue has not been addressed in the literature. The importance of considering the effect of the flux penetrating\rthe surrounding air is shown in this paper using finite element simulations and experimental results, and an analytical\rapproach is proposed to consider this effect on magnet operating point determination and performance prediction of\rsaturated brushed permanent magnet DC motors. An analytical method is also presented to determine the boundary\rradius of the surrounding air for obtaining accurate results in finite element (FE) solutions and analytical calculations.\rAn analytical approach based on Carter’s coefficient is also proposed to calculate the effective length of the magnet when\rthe length of the magnet and rotor length are not the same. The accuracy of the proposed analytical model is illustrated\rusing finite element simulations and experimental results. With this accuracy, this analytical model is very suitable to\rbe used for reliable and quick mathematical design optimization.
The Armenian Massacres in Ottoman Turkey: a Disputed Genocide /Guenter Lewy ,salt Lake City, University of Utah Press, 2005, 370 Sayfa.
(2006) Uzer, Umut
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Citation - WoS: 12
Citation - Scopus: 12
Association between monocyte to high-density lipoprotein cholesterol ratio and bicuspid\raortic valve degeneration
(Tubitak Scientific & Technological Research Council Turkey, 2020) Karaduman, Bilge Duran; Ayhan, Hüseyin; Keles, Telat; Bozkurt, Engin
Background/aim: From a pathophysiological point of view, inflammation is thought to be more dominant in bicuspid aortic valve\r(BAV) stenosis than tricuspid aortic valve (TAV) stenosis. Our study aimed to determine the association between monocyte to highdensity lipoprotein cholesterol (HDL-C) ratio (MHR), a new inflammatory marker, and the speed of progression of stenosis and\rpathophysiology of BAV stenosis.\rMaterials and methods: A total of 210 severe aortic stenosis patients (70 consecutive BAV patients, 140 matched TAV patients) were\rretrospectively enrolled in the study. Clinical and echocardiographic data and laboratory results related to our research were collected\rretrospectively from the patients’ records. MHR was measured as the ratio of the absolute monocyte count to the HDL-C value.\rResults: Seventy BAV (mean age: 72.0 ± 9.1 years, 42.9% female) and 140 TAV patients (mean age: 77.9 ± 8.3 years, 51.4% female)\rwith severe aortic stenosis were enrolled in this study. There was no difference between the two groups in terms of another baseline\rdemographic or clinic findings except age (P < 0.001). Monocyte count, hemoglobin level, mean platelet volume was significantly\rhigher, and HDL-C level was significantly lower in the BAV group, while other lipid and CBC parameters were found to be similar. In\rthe multivariate analysis, MHR (P = 0.005, 95% CI: 0.90–0.98) and, as expected, age (P = 0.001, 95% CI: 1.02–1.11) were found to be\rsignificant as the independent predictor of BAV, after adjusting for other risk factors.\rConclusion: Our study showed a significant correlation between increased MHR and BAV. MHR was determined as a significant\rindependent predictor for the speed of progression and diagnosis of severe BAV stenosis in multivariate analysis.
Characterizations of the Commutators Involving Idempotents in Certain Subrings of $m_{2}(\\mathbb{z})$
(2023) Gümüşel, Günseli; Özdın, Tufan
In this paper, we characterize the idempotency, cleanness, and unit-regularity of the commutator $[E_1, E_2]$ = $E_1E_2 − E_2E_1$ involving idempotents $E_1, E_2$ in certain subrings of $M_2(Z)$.
China-Africa Relations in the 21st Century : Engagement,compromise and Controversy
(2009) Uchehara, E.kieran
Çin’in Afrika ile ilgili dış politika gündemi, gelişmekte olan ülkeler arasındaki işbirliğini artırma ve yükselen bir süper güç olarak statüsünü gösterme hamlesinin bir parçasını oluşturmaktadır. 2000 Pekin Deklarasyonu ve Çin-Afrika Ekonomik ve Siyasi işbirliği Programı yenilenen ilişkilerin temelini oluşturmaktadır. Çin, Afrika ile tüm karşılıklı ilişki alanlarında Afrika ile farklı ve çeşitli ilişkiler geliştirmiştir. Ancak Çin’in büyüyen sanayisinin ihtiyaç duyduğu Afrika’nın maden ve enerji kaynakları, 21. yüzyılda Çin’in Afrika ile iyi ilişkiler kurmasının ana sebebidir. Çin’in Afrika’daki ticaret ve yatırımındaki hızlı artış, kıtanın kalkınması ile ilgili fırsatlar ve zorlukların yapısına ilişkin ve Batı ile olduğu gibi yeni-sömürgeci tarzı ilişkilerin gelişme ihtimalinin olup olmadığı konusunda akademisyenler ve siyasiler arasındaki uyuşmazlıkları açığa çıkarmıştır. Kısmen ekonomik asimetrilerden kaynaklanan ticari ve yatırım ilişkilerindeki dengesizlik, Çin’in Afrikalı baskıcı yönetimleri kınamaması ve iyi yönetilmeyen ekonomiler; kendisine hizmet eden ve kısa dönem kazanımlardan etkilenen bir dış ekonomik politikayı işaret etmektedir.
Citation - WoS: 1
Citation - Scopus: 3
The Clinical and Demographical Characteristics of Turkish Pediatric Lymphedema Patients: a Multicenter Study
(Tubitak Scientific & Technological Research Council Turkey, 2022) Borman, Pinar; Balcan, Aysegul; Eyigor, Sibel; Coskun, Evrim; Ayhan, Figen; Cakit, Burcu Duyur; Dogan, Sevil Ceyhan
Background/aim: Reducing lymphedema-associated burden and disability in the pediatric setting requires improved awareness and understanding clinical properties of the lymphedema. The aim of this study was to evaluate the clinical and demographic characteristics of patients with pediatric lymphedema presented to different lymphedema centers in Turkey. Materials and methods: The socio-demographic and clinical characteristics of the children including age, gender, presence of genetic syndromes, duration of edema, site and stage of lymphedema and the received therapies were determined. Parental and children education on self-management techniques were recorded. Results: A total of 122 children (female: 66, male: 56) with a mean age of 120.7 +/- 71.2 months were included from 7 centers. Of them; 92% had primary, 8% had secondary lymphedema mostly due to infection and trauma. Lymphedema was part of a syndrome in 18% of the children. The most common site of involvement was the lower extremity, followed by upper extremity and genital involvement. Lymphedema was complicated in 17 % of children, mainly with a clinical picture of cellulitis, infection, and pain. The median duration of lymphedema was 41 (5-216) months. Although most of the children had stage 2 lymphedema, only 40% of them received treatment. The most commonly received treatment was compression therapy. No family or child was educated for self-care management before. Conclusion: In conclusion, pediatric lymphedema has a comparable gender distribution and usually involves the lower extremities. Although most of the children had advanced disease, more than half of the patients did not receive any treatment indicating the unmet need for management of lymphedema. The education of patients and/or children about self-management methods were lacking. We suggest educational activities for both families of children with lymphedema and health care providers, in order to facilitate early reference to lymphedema units and to receive prompt preventive and therapeutic approaches for this suffering condition.
Citation - WoS: 1
Citation - Scopus: 2
A Convergent Two-Level Linear Scheme for the Generalized Rosenau–kdv–rlw Equation
(Tubitak Scientific & Technological Research Council Turkey, 2019) Aydın, Ayhan
A new convergent two-level finite difference scheme is proposed for the numerical solution of initial valueproblem of the generalized Rosenau–KdV–RLW equation. The new scheme is second-order, linear, conservative, andunconditionally stable. It contains one free parameter. The impact of the parameter to error of the numerical solutionis studied. The prior estimate of the finite difference solution is obtained. The existence, uniqueness, and convergence ofthe scheme are proved by the discrete energy method. Accuracy and reliability of the scheme are tested by simulating thesolitary wave graph of the equation. Wave generation subject to initial Gaussian condition has been studied numerically.Different wave generations are observed depending on the dispersion coefficients and the nonlinear advection term.Numerical experiments indicate that the present scheme is conservative, efficient, and of high accuracy, and well simulatesthe solitary waves for a long time.
Citation - WoS: 4
Citation - Scopus: 2
The Effect of Combined Hydrolyzed Type 2 Collagen, Methylsulfonylmethane, Glucosamine Sulfate and Chondroitin Sulfate Supplementation on Knee Osteoarthritis Symptoms
(Baycinar Medical Publ-baycinar Tibbi Yayincilik, 2024) Ayhan, Fikriye Figen; Çoban, Ayşegül Demirci; Karasu, Ayça Utkan; Karaoğlan, Belgin; Çınar, Ece; Eyigör, Sibel; Dalyan, Meltem
Objectives: This study aimed to evaluate the effects of the combined hydrolyzed type 2 collagen, methylsulfonylmethane (MSM), glucosamine sulfate (GS), and chondroitin sulfate (CS) supplement on knee pain intensity in patients with knee osteoarthritis (OA). Patients and methods: This multicenter, observational, noninterventional study included 98 patients (78 females, 20 males; mean age: 52.8±6.5 years; range, 40 to 64 years) who had Grade 1-3 knee OA between May 2022 and November 2022. The patients were prescribed the combination of hydrolyzed type 2 collagen, MSM, GS, and CS as a supplement for knee OA. The sachet form of the combined supplement containing 1250 mg hydrolyzed type 2 collagen, 750 mg MSM, 750 mg GS, and 400 mg CS was used once daily for two consecutive months. Patients were evaluated according to the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Visual Analog Scale (VAS)-pain, and Health Assessment Questionnaire (HAQ). Patients were scheduled to visit for follow-up four weeks (Visit 2) and eight weeks (Visit 3) after Visit 1 (baseline; day 0 of the study). Results: For the VAS-pain, WOMAC, WOMAC-subscale, and HAQ scores, the differences in improvement between the three visits were significant (p<0.001 for all). The patient compliance with the supplement was a median of 96.77%, both for Visit 2 and Visit 3. Conclusion: The combination of hydrolyzed type 2 collagen, MSM, GS, and CS for eight weeks in knee OA was considered an effective and safe nutritional supplement.
Citation - WoS: 6
Citation - Scopus: 6
Exact and Nonstandard Finite Difference Schemes for the Burgers Equation B(2, 2)
(Tubitak Scientific & Technological Research Council Turkey, 2021) Köroğlu, Canan; Aydın, Ayhan
In this paper, we consider the Burgers equation B(2, 2) . Exact and nonstandard finite difference schemes(NSFD) for the Burgers equation B(2, 2) are designed. First, two exact finite difference schemes for the Burgers equationB(2, 2) are proposed using traveling wave solution. Then, two NSFD schemes are represented for this equation. Thesetwo NSFD schemes are compared with a standard finite difference (SFD) scheme. Numerical results show that the NSFDschemes are accurate and efficient in the numerical simulation of the kink-wave solution of the B(2, 2) equation. We seethat although the SFD scheme yields numerical instability for large step sizes, NSFD schemes provide reliable results forlong time integration. Local truncation errors show that the NSFD schemes are consistent with the B(2, 2) equation.
An Exhaustive Computer Search for Finding New Curves With Many Points Among Fibre Products of Two Kummer Covers Over $\\bbb{f}_5$ and $\\bbb{f}_7$
(2013) Özbudak, Ferruh; Temür, Burcu Gülmez; Yayla, Oğuz
In this paper we make an exhaustive computer search for finding new curves with many points among fibre products of 2 Kummer covers of the projective line over F5 and F7 . At the end of the search, we have 12 records and 6 new entries for the current Table of Curves with Many Points. In particular, we observe that the fibre product $y^3_1$ = $\\frac {5(x+2)(x +5)} {x}$, $y^3_2$ $\\frac {3x^2(x +5)} {x + 3}$ over F7 has genus 7 with 36 rational points. As this coincides with the Ihara bound, we conclude that the maximum number N7 (7) of F7 -rational points among all curves of genus 7 is 36. Our exhaustive search has been possible because of the methods given in the recent work by Özbudak and Temür (2012) for determining the number of rational points of such curves.
An Expansion Result for a Sturm-Liouville Eigenvalue Problem With Impulse
(2010) Faydaoğlu, Şerife; Guseınov, Gusein Sh.
The paper is concerned with an eigenvalue problem for second order differential equations with impulse. Such a problem arises when the method of separation of variables applies to the heat conduction equation for two-layered composite. The existence of a countably infinite set of eigenvalues and eigenfunctions is proved and a uniformly convergent expansion formula in the eigenfunctions is established.
Fedja’s Proof of Deepti’s Inequality
(Tubitak Scientific & Technological Research Council Turkey, 2018) Ostrovska, Sofiya; Turan, Mehmet
The paper aims to present, in a systematic way, an elegant proof of Deepti’s inequality. Both the inequalityand various ideas concerning the issue were discussed on the Mathoverflow website by a number of users, but none haveappeared in the literature thus far. In this work, suggestions pertaining to users ‘Deepti’ and ‘fedja’ are traced, whencethe title. The results or the paper are new, and the proof is divided into a series of statements, many of which are ofinterest in themselves.
Citation - Scopus: 2
Field Extensions Having the Unique Subfield Property, and G-Cogalois Extensions
(2002) Albu,T.
We present a short proof, based on Cogalois Theory, of a result due to Acosta de Orozco and Vélez (1982, J. Number Theory 15, 388-405) characterizing separable simple radical field extensions with the unique subfield property, and prove that these extensions are precisely the simple G-Cogalois extensions with a cyclic Kneser group. © TÜBİTAK.
Fitting a Recurrent Dynamical Neural Network To Neural Spiking Data: Tackling the Sigmoidal Gain Function Issues
(Tubitak Scientific & Technological Research Council Turkey, 2019) Doruk, Reşat Özgür
This is a continuation of a recent study (Doruk RO, Zhang K. Fitting of dynamic recurrent neural networkmodels to sensory stimulus-response data. J Biol Phys 2018; 44: 449-469), where a continuous time dynamical recurrentneural network is fitted to neural spiking data. In this research, we address the issues arising from the inclusion ofsigmoidal gain function parameters to the estimation algorithm. The neural spiking data will be obtained from the samemodel as that of Doruk and Zhang, but we propose a different model for identification. This will also be a continuoustime recurrent neural network, but with generic sigmoidal gains. The simulation framework and estimation algorithmsare kept similar to that of Doruk and Zhang so that we can have a solid base to compare the results. We evaluatethe estimation performance in two different ways. First, we compare the firing rate responses of the original and theestimated model. We find that responses of both models to the same stimuli are similar. Secondly, we evaluate variationsof the standard deviations of the estimates against a number of samples and stimulus parameters. They show a similarpattern to that of Doruk and Zhang. We thus conclude that our model serves as a reasonable alternative provided thatfiring rate is the response of interest (to any stimulus).
Citation - WoS: 1
From Partners To Rivals: Normative Power Europe Meets Normative Power China
(International Relations Council of Turkey, 2025) Sahin, Gözde Yilmaz
The European Union (EU) has been promoting its norms, values, and rules for decades. However, in the current international environment, the EU’s normative power is not being received well outside the EU, particularly in reference to the growing power of illiberal states. Within that context, this study explores EU-China relations across time and unpacks the position of normative power Europe towards China and the Chinese response. The study foregrounds the fruitless attempts of the EU to project its transformative power onto China and the growing resistance by China against this, which it expresses by presenting itself to the West as an alternative power with an alternative understanding of international politics.
Hydrogen Implantation Effects on the Electrical and Optical Properties of Inse Thin Films
(2012) Qasrawı, Atef Fayez; Ilaıwı, Khaled Faysal; Polımenı, Antonio
The effects of hydrogen ion implantation on the structural, electrical and optical properties of amorphous InSe thin films have been investigated. X-ray diffraction analysis revealed no change in the structure of the films. An implantation of 7.3 × $10^{18}$ ions/$cm^2$ decreased the electrical conductivity by three orders of magnitude at 300 K. Similarly, the conductivity activation energy, which was calculated in the temperature range of 300–420 K, decreased from 210 to 78 meV by H-ion implantation. The optical measurements showed that the direct allowed transitions energy band gap of amorphous InSe films has decreased from 1.50 to 0.97 eV by implantation. Furthermore, significant decreases in the dispersion and oscillator energy, static refractive index and static dielectric constants are also observed by hydrogen implantation.
Citation - WoS: 8
Citation - Scopus: 9
Impact of Hospital-Acquired Acute Kidney Injury on Covid-19 Outcomes in Patients With and Without Chronic Kidney Disease: a Multicenter Retrospective Cohort Study
(Tubitak Scientific & Technological Research Council Turkey, 2021) Ozturk, Savas; Turgutalp, Kenan; Arıcı, Mustafa; Çetinkaya, Hakkı; Altıparmak, Mehmet Rıza; Aydın, Zeki; Ateş, Kenan
Background/aim: Hospital-acquired acute kidney injury (HA-AKI) may commonly develop in Covid-19 patients and is expected to have higher mortality. There is little comparative data investigating the effect of HA-AKI on mortality of chronic kidney disease (CKD) patients and a control group of general population suffering from Covid-19. Materials and methods: HA-AKI development was assessed in a group of stage 3–5 CKD patients and control group without CKD among adult patients hospitalized for Covid-19. The role of AKI development on the outcome (in-hospital mortality and admission to the intensive care unit [ICU]) of patients with and without CKD was compared. Results: Among 621 hospitalized patients (age 60 [IQR: 47–73]), women: 44.1%), AKI developed in 32.5% of the patients, as stage 1 in 84.2%, stage 2 in 8.4%, and stage 3 in 7.4%. AKI developed in 48.0 % of CKD patients, whereas it developed in 17.6% of patients without CKD. CKD patients with HA-AKI had the highest mortality rate of 41.1% compared to 14.3% of patients with HA-AKI but no CKD (p < 0.001). However, patients with AKI+non-CKD had similar rates of ICU admission, mechanical ventilation, and death rate to patients with CKD without AKI. Adjusted mortality risks of the AKI+non-CKD group (HR: 9.0, 95% CI: 1.9–44.2) and AKI+CKD group (HR: 7.9, 95% CI: 1.9–33.3) were significantly higher than that of the non-AKI+non-CKD group. Conclusion: AKI frequently develops in hospitalized patients due to Covid-19 and is associated with high mortality. HA-AKI has worse outcomes whether it develops in patients with or without CKD, but the worst outcome was seen in AKI+CKD patients.Key words: Acute kidney injury, chronic kidney disease, Covid-19, hospitalization, mortality
Introduction: Marxifying IR, IRifying Marxism
(International Relations Council of Turkey, 2024) Yalvaç,F.; Joseph,J.
Although the neglect of Marxism has been a pervasive characteristic of IR theory, there has been a marked revival of interest in Marxism. Marx’s materialist insights into the general historical development of societies, as well as his critique of capitalism and political economy, have served as alternative starting points for different critical approaches to IR and offers a welcome alternative to neorealism, constructivism, and poststructuralism that have dominated IR for several decades. Marxism provides a redefinition of IR by focusing on changes in material circumstances, historical conditions, and society instead of assuming unchanging and fixed structures of anarchy or the state. Marx’s analysis and insights into the dynamics of international relations have become even more important given the ongoing crisis of neoliberal capitalism, the rise of authoritarianism, right-wing nationalist populisms, and the racial and gendered subordinations accompanying them pointing to the importance of Marxifying IR and IRifying Marxism. © 2024, International Relations Council of Turkey. All rights reserved.

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