TR Dizin İndeksli Yayınlar Koleksiyonu / TR Dizin Indexed Publications Collection
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Article Citation - Scopus: 2A Bibliometric Analysis of Publications on Emergency Medicine in Turkiye(Wolters Kluwer Medknow Publications, 2024) Guzelce, Mustafa Can; Orhan, Ertug; Ozgur, SeferOBJECTIVES: Publications and literature related to emergency medicine (EM) have been consistently increasing. There are 4048 studies in total in the EM journals published until the present day in Turkiye in the Web of Science (WoS) database. Our aim is to define the bibliometric features of scientific studies published in EM journals in Turkiye, to gain insights into the trends of the literature. METHODS: We retrospectively analyzed the bibliometric data of scientific studies published in EM journals in Turkiye until today on the WoS database related to the EM field. The bibliometrix package of R statistical software was used in the bibliometric analyses in the study. RESULTS: A total of 4048 scientific studies from Turkiye indexed on the WoS database from 10,263 authors in four different journals were analyzed. Among these, 3681 (90.9%) were articles, 188 (4.7%) were reviews, 97 (2.4%) were editorial material, 60 (1.5%) were letters, and 5 (0.1%) were corrections. Average number of citations per study was 3.6, with the most cited study having 2016 citations. The most frequent title's words were emergency, patient, and acute. CONCLUSION: This study shows that there is an increasing trend in the number of EM publications and citations in Turkiye with the first most cited study having 2016 citations, and the top contributing countries were Turkiye, Iran, and India. The results of this study may be useful in understanding the historical and prospective development of EM, including the identification of general information about its publications, differentiation of the top-cited ones, and presentation of a bibliometric analysis of scientific activity to date.Article Can Volumetric Magnetic Resonance Imaging Evaluations Be Helpful in the Follow-Up of Cognitive Functions in Cognitively Normal Parkinson's Disease Patients?(Tubitak Scientific & Technological Research Council Turkey, 2024) Uysal, Hasan Armağan; Hunerli, Duygu; Çakmur, Raif; Dönmez Çolakoğlu, Beril; Ada, Emel; Yener, GörsevBackground/aim: In this study, besides the evaluation of gray and white matter changes in cognitively normal Parkinson's disease (PDCN) patients with volumetric magnetic resonance imaging (MRI) parameters, it was tried to show that some neuropsychological tests may be impaired in PD-CN patients. Materials and methods: Twenty-six PD-CN patients and 26 healthy elderly (HC) participants were included in the current study. Global cognitive status was assessed using the mini-mental state examination (MMSE), and the Montreal cognitive assessment scale (MoCA). Attention and executive functions were evaluated using the Wechsler memory scale-revised (WMS-R) digit span test and trail making test (TMT) part A and part B, the Stroop test, semantic and phonemic fluency tests, and clock drawing test. Magnetic resonance imaging (MRI) was acquired according to the Alzheimer's disease neuroimaging initiative (ADNI) protocol. Results: There were no significant differences among groups regarding age, sex, handedness, and years of education. In the comparison of the PD-CN group and the HC group, there was a statistical decrease in the total animal scores, lexical fluency, TMT part A and TMT part B scores in the PD-CN group. Subcortical gray matter volumes (GMV) were significantly lower in PD-CN patients. The PD-CN group had a significantly reduced total volume of right putamen and left angular gyrus compared to that in the HC group. We observed that putamen and angular gyrus volumes were lower in PD-CN patients. On the other hand, TMT part B may be a useful pretest in detecting the conversion of mild cognitive impairment in PD. Conclusion: Significant MRI volumetric measurements and neuropsychological test batteries can be helpful in the clinical follow-up in PD-CN patients.Article Citation - WoS: 9Citation - Scopus: 9Classical Heart Rate Variability and Non-Linear Heart Rate Analysis in Mice Under Na-Pentobarbital and Ketamine/Xylazine Anesthesia(Tubitak Scientific & Technical Research Council Turkey, 2022) Kazdagli, Hasan; Ozel, Hasan Fehmi; Ozbek, Mustafa; Alpay, Suheda; Alenbey, MuruvvetBackground/aim: Anesthetics are often used in animal experiments to achieve immobilization and relieve pain. However, many anesthetics can alter the dynamics of cardiovascular systems. We aimed to compare the effects of two frequently used anesthetics agents on heart rate variability (HRV) parameters in mice. Materials and methods: This observational study was performed between May and June 2014 in 21 male BALB/c mice aged 16-20 weeks. The animals were divided into three groups: pentobarbital (P), (n = 7); pentobarbital+fentanyl (P+ F), (n = 7); and ketamine+xylazine (K+X), (n = 7). Surface electrocardiography (ECG) electrodes were placed in lead II configuration. 'the tachogram of RR intervals was obtained after R waves were detected using the Pan-Tompkins real-time QRS recognition algorithm. Frequency-domain, time-domain, and nonlinear HRV analyses were performed. Results: The bradycardia effect was higher in the K+X group (p < 0.01). Time-domain indices were higher in group K+X compared to group P (p < 0.01) and group P+F (p < 0.001). Very low frequency (VLF) power was significantly lower in group K+X compared to group P and group P+F (p < 0.01). Low frequency (LF) power, low frequency/high frequency (LF/HF) ratio, and total power (TP) were higher in group K+X compared to group P (p < 0.01) and group P+F (p < 0.001). The detrended fluctuation analysis short-term parameter (DFA alpha(1)) was significantly higher in group K+X compared to group P+F (p < 0.05) and the long-term parameter (DFA alpha(2)) was lower in group K+X compared to group P (p < 0.05). Standard deviations SD1 and SD2 were higher in group K+X compared to group P (p < 0.001) and group P+F (p < 0.001), SD2/SD1 ratio was lower in group K+X compared to group P (p < 0.05) and group P+F (p < 0.05). Entropy measures did not differ between groups. Conclusion: HRV analyses, including nonlinear methods, indicated that a K+X combination reduces imbalance and disorder in the regulation of the autonomic nervous system (ANS) in comparison to both P and the P+F combination.Article A Convergent Algorithm for a Cascade Network of Multiplexed Dual Output Discrete Perceptrons for Linearly Nonseparable Classification(Tubitak Scientific & Technical Research Council Turkey, 2014) Genc, Ibrahim; Guzelis, CuneytIn this paper a new discrete perceptron model is introduced. The model forms a cascade structure and it is capable of realizing an arbitrary classification task designed by a constructive learning algorithm. The main idea is to copy a discrete perceptron neuron's output to have a complementary dual output for the neuron, and then to select, by using a multiplexer, the true output, which might be 0 or 1 depending on the given input. Hence, the problem of realization of the desired output is transformed into the realization of the selector signal of the multiplexer. In the next step, the selector signal is taken as the desired output signal for the remaining part of the network. The repeated applications of the procedure render the problem into a linearly separable one and eliminate the necessity of using the selector signal in the last step of the algorithm. The proposed modification to the discrete perceptron brings universality with the expense of getting just a slight modification in hardware implementation.Article Citation - WoS: 32Citation - Scopus: 32Covid-19 Anxiety in People Living With Hiv: an Online Cross-Sectional Study(Tubitak Scientific & Technical Research Council Turkey, 2020) Kuman Tuncel, Ozlem; Pullukcu, Husnu; Erdem, Huseyin Aytac; Kurtaran, Behice; Tasbakan, Selin Ece; Isikgoz Tasbakan, MeltemBackground/aim: The emergence of the coronavirus disease 2019 (COVID-19) outbreak has had an enormous emotional impact on sonic vulnerable groups, such as people living with human immunodeficiency virus (HIV) (PLHIV). This study was planned with the aim of assessing the anxiety levels of PLHIV and the sources of their anxiety. Materials and methods: A web-based questionnaire was sent to PLHIV using the virtual snowball sampling method. The questionnaire included questions about sociodemographic status, information about HIV infection, and the Beck Anxiety Inventory (BAI). Additionally, some opinions of the participants about COVID-19 were asked. Results: A total of 307 respondents, with a median age of 33 years, from 32 different cities, participated in the study. More than half of the respondents reported the belief that COVID-19 was not sufficiently well-known by the medical community and nearly 45% believed that they would have snore complications if they contracted COVID-19. One-fourth of the participants had anxiety. Having a preexisting psychiatric disorder, perceiving that they were practicing insufficient preventive measures, not being sure about the presence of any individuals with COVID-19 in their environment, and living with a household member with a chronic disease were found to be the risk factors of PLHIV for having anxiety during this pandemic. The BAI scores were correlated with the patient-reported anxiety levels about the spread of COVID-19 in Turkey, acquiring COVID-19, transmitting COVID-19 to another person, and transmitting HIV to another person. Among the stated conditions, the most common concern was the spread of COVID-19 all over the country, while the least common was transmitting HIV to someone else. Conclusion: The results revealed that a significant proportion of the sample had anxiety, and the findings were essential for developing evidence-based strategies for decreasing the anxiety of PLHIV, especially for those who had risk factors and to provide them with better health care during this pandemic or other pandemic-like crises.Article Duchenne Muscular Dystrophy Patients Diagnosed at the Asymptomatic Stage: What Are the Benefits of Early Diagnosis(Turkish Society of Physical Medicine and Rehabilitation, 2025) Sertpoyraz, Filiz Meryem; Tanigor, Goksel; Baydan, Figen; Kale, Murat YildirimObjectives: This study aimed to demonstrate whether a diagnosis given at the asymptomatic stage of patients with DMD can affect the clinical outcomes and to define the clinical characteristics of the patients. Patients and methods: The cross-sectional study was conducted with 136 male patients (mean age: 8.8±3.7 years; range, 3 to 17 years) with DMD between March 2022 and February 2023. The patients were diagnosed through clinical presentation, pathology studies, and genetic testing. The demographic, clinical, and the laboratory data of the patients were recorded. The patients were evaluated in two groups: those diagnosed at the asymptomatic stage due to elevated creatine kinase (CK) and those diagnosed due to clinical symptoms. Patients were further stratified according to their age groups: those younger than 10 years and those aged 10 years or older. Hand grip, quadriceps muscle strength, and Vignos and Brooke motor functional assessment scales of the two groups were compared. Results: In patients who were diagnosed with CK levels, CK elevation was significantly more common than other findings. When the age at diagnosis was evaluated, the age at diagnosis in those diagnosed with CK levels was statistically significantly lower than in those diagnosed with clinical findings. No significant difference was detected in clinical findings between the groups under the age of 10 years. Among patients aged 10 years or older, hand muscle strength, quadriceps muscle strength, and Vignos and Brooke motor function scale scores were significantly better in those diagnosed with CK levels compared to those diagnosed with clinical findings. Conclusion: This study shows that early diagnosis in the preclinical period, which enables earlier medical treatment and rehabilitation, may have a positive effect on motor functions and the course of the disease.Article Citation - Scopus: 1Effects of 1-(2 (trim) on Receptor-Independent And-Dependent Contractile Responses in Rat Aorta(Tubitak Scientific & Technical Research Council Turkey, 2016) Selli, Cigdem; Erac, Yasemin; Tosun, MetinerBackground/aim: This study investigates whether 1-(2-trifluoromethylphenyl)-imidazole (TRIM), originally proposed as a nitric oxide synthase inhibitor and also suggested to be an inhibitor of store-operated calcium entry in mouse anococcygeal muscle, inhibits receptor-independent and -dependent responses in rat thoracic aorta. Materials and methods: Cyclopiazonic acid-and serotonin-induced vascular responses were investigated in aortic segments isolated from male Sprague Dawley rats using isolated tissue experiments. Changes in intracellular calcium levels were also monitored via front surface fluorescence measurements in fura-2-loaded embryonic rat vascular smooth muscle cell line A7r5. Results: TRIM inhibited serotonin-mediated vascular contractions without affecting cyclopiazonic acid-induced responses. In addition, TRIM caused a nonlinear rightward shift in the serotonin concentration-response curve, possibly via serotonin receptor modulation. Conclusion: TRIM may have an impact on investigation of tissue-specific receptor-independent and -dependent vascular responses. It may also be used as a lead compound in the development of selective serotonin receptor modulators.Article Citation - WoS: 3Citation - Scopus: 6Effects of Bevacizumab Administration on the Hypoxia- Induced Pulmonary Hypertension Rat Model(Tubitak Scientific & Technical Research Council Turkey, 2021) Demir, Canan; Karaman, Meral; Ucan, Eyup Sabri; Gokmen, Ali Necati; Gurel, Duygu; Coker, Sadiye Canan; Adali, YasemenBackground/aim: Bevacizumab is a chemotherapeutic drug, which selectively binds to vascular endothelial growth factor (VEGF) and mainly inhibits angiogenesis and neovascularization. We aimed to study the possible effects of bevacizumab on right ventricular pressure (RVP), right ventricular hypertrophy, and VEGF, in hypoxia -induced pulmonary hypertension (PH) rat model. Materials and methods: 24 adult Wistar Albino rats were randomly divided into four groups: control group -saline; Bevacizumab Group; PH Group; PH + Bevacizumab Group. In hypoxia -induced model, 10% oxygen and 90% nitrogen were applied in a plexiglas box for eight days to PH Group and PH + Bevacizumab Group. On day eight, RVPs were measured directly from the heart, and then animals were sacrificed. Heart and lung tissues were examined, and Fulton index was measured. Results: RVP, Fulton index, and tissue VEGF scores were significantly lower in PH + Bevacizumab group than PH group: median (ranges), RVP, mmHg, 37.8 (33.0-39.0) and 32.3 (28.0-35.0), p: 0.01; Fulton index: 0.30 (0.29-0.33) and 0.25 (0.24-0.26), p: 0.003; tissue VEGF scores: 5.1 (4.8-5.3) and 4.0 (3.8 4.1), p: 0.004, respectively. Conclusion: Bevacizumab, which is indeed an antineoplastic agent, might have a favorable effect on hypoxia -induced pulmonary hypertension.Article Citation - WoS: 5Citation - Scopus: 5The Effects of Playing Digital Games on Children's Pain, Fear, and Anxiety Levels During Suturing: a Randomized Controlled Study(Wolters Kluwer Medknow Publications, 2023) Kavlakcı, Muhammet; Öğce, Filiz; Yavan, TulayOBJECTIVE: The aim was to determine the effects of digital game play on children's pain, fear, and anxiety levels during suturing. METHODS: Data were obtained from 84 children between the ages of 8 and 17 years at the pediatric emergency department between January 16 and March 19, 2020, using the Socio-Demographic and Clinical Characteristics Form, the Wong-Baker Faces Pain Rating Scale (WBFPS), the Visual Analogue Scale (VAS), the Fear of Medical Procedures Scale (FMPS), and the State-Trait Anxiety Inventory for Children (STAI-CH). A four-block randomization system was used. The study group (n = 42) played digital games during the suturing procedure, unlike the control group (n = 42). Ethical permissions were obtained from the ethical committee, hospital, and families. RESULTS: Before the suturing procedure, there was no statistically significant difference between the groups' mean scores. The intervention group was found to have statistically significantly lower WBFPS and VAS pain scores than the control group during the suturing procedure, and after the procedure, statistically significantly lower WBFPS, VAS, FMPS, and STAI-CH mean scores than the control group. CONCLUSIONS: The digital game-playing approach applied before and during the suture procedure was found to be effective in reducing children's pain, fear, and anxiety levels.Article Enlarging Multiword Expression Dataset by Co-Training(Scientific Technical Research Council Turkey-Tubitak, 2018) Kumova Metin, SenemIn multiword expressions (MWEs), multiple words unite to build a new unit in language. When MWE identification is accepted as a binary classification task, one of the most important factors in performance is to train the classifier with enough number of labelled samples. Since manual labelling is a time-consuming task, the performances of MWE recognition studies are limited with the size of the training sets. In this study, we propose the comparison-based and common-decision co-training approaches in order to enlarge the MWE dataset. In the experiments, the performances of the proposed approaches were compared to those of the standard co-training [1] and manual labelling where statistical and linguistic features are employed as two different views of the MWE dataset [2]. A number of tests with different settings were performed on a Turkish MWE dataset. Ten different classifiers were utilized in the experiments and the best performing classifier pair was observed to be the SMO-SMO pair. The experimental results showed that the common-decision co-training approach is an alternative to hand-labeling of large MWE datasets and both newly proposed approaches outperform the standard co-training [2] when the training set is to be enlarged in MWE classification.Book Review Ethnic Boundaries in Turkish Politics: the Secular Kurdish Movement and Islam(Uluslararasi Iliskiler Konseyi Dernegi, 2019) Al, Serhun[Abstract Not Available]Article Citation - WoS: 11Citation - Scopus: 14Evaluation of Mother Wavelets on Steady-State Visually-Evoked Potentials for Triple-Command Brain-Computer Interfaces(Tubitak Scientific & Technical Research Council Turkey, 2021) Sayilgan, Ebru; Yuce, Yilmaz Kemal; Isler, YalcinWavelet transform (WT) is an important tool to analyze the time-frequency structure of a signal. The WT relies on a prototype signal that is called the mother wavelet. However, there is no single universal wavelet that fits all signals. Thus, the selection of mother wavelet function might be challenging to represent the signal to achieve the optimum performance. There are some studies to determine the optimal mother wavelet for other biomedical signals; however, there exists no evaluation for steady-state visually-evoked potentials (SSVEP) signals that becomes very popular among signals manipulated for brain-computer interfaces (BCIs) recently. This study aims to explore, if any, the mother wavelet that suits best to represent SSVEP signals for classification purposes in BCIs. In this study, three common wavelet-based features (variance, energy, and entropy) extracted from SSVEP signals for five distinct EEG frequency bands (delta, theta, alpha, beta, and gamma) were classified to determine three different user commands using six fundamental classifier algorithms. The study was repeated for six different commonly-used mother wavelet functions (haar, daubechies, symlet, coiflet, biorthogonal, and reverse biorthogonal). The best discrimination was obtained with an accuracy of 100% and the average of 75.85%. Besides, ensemble learner gives the highest accuracies for half of the trials. Haar wavelet had the best performance in representing SSVEP signals among other all mother wavelets adopted in this study. Concomitantly, all three features of energy, variance, and entropy should be used together since none of these features had superior classifier performance alone.Article Citation - Scopus: 1Evaluation of Response to Treatment in Breast Cancer-Related Lymphedema(Turkish Society of Physical Medicine and Rehabilitation, 2025) Eyigor, Sibel; Çınar, Ece; Tanigor, Goksel; İnbat, Menekse Ozgur; Güvercin, Ezgi Yıldız; Kabayel, Sedef ÇalışkanObjectives: The primary objective of this study was to assess and compare the response to the breast cancer-related lymphedema (BCRL) treatment with Breast Cancer-Related Lymphedema of the Upper Extremity (CLUE) scores, bioimpedance spectroscopy (BIS), and the volume-assessments /measurements. The secondary objective of the study was to investigate whether CLUE played a role in the treatment response and to examine its correlation with the other measures of lymphedema. Patients and methods: Between January 2019 and June 2019, a total of 40 patients (2 males, 38 females; mean age: 57.8±12.5 years; range, 45 to 70 years) who were diagnosed with unilateral Stage 2-3 BCRL and underwent treatment were included. The patients’ upper extremity volumes were assessed and the patients were evaluated with the CLUE score, the Disabilities of the Arm, Shoulder, and Hand Outcome Measure (QuickDASH) score, BIS, and hand grip strength before and after the complete decongestive therapy. Results: Correlation analyses revealed that CLUE total score and BIS values were correlated with the reduction in the volumes (p=0.04 and p<0.001, respectively). The CLUE total score was also found to be positively correlated with the BIS values (p<0.001). Hand grip strength and QuickDASH scores were not found to be correlated with the changes in the volume and CLUE total scores. Conclusion: The development of a structured clinical assessment such as CLUE provides clinicians for a standardized evaluation for BCRL. The diagnosis of subclinical lymphedema can be detected earlier by using the BIS and CLUE scale and lymphedema comorbidity and treatment costs can be reduced.Article Evaluation of the Relationship Between Diabetic Retinopathy and the Development of Left Atrial Stiffness in Patients With Diabetes Mellitus(AVES, 2023) Birdal, Oğuzhan; Saygı, Mehmet; Doğan, Remziye; Pay, Levent; Aksakal, Emrah; Topaloglu, Caner; Yıldırım, MustafaObjective: Based on several studies, atrial remodeling results in an increase in left atrial (LA) stiffness, which is indicative of a worsened reservoir function. A typical microvascular consequence of diabetes mellitus (DM) is diabetic retinopathy. Therefore, the objective of this study was to assess the factors that might be related to LA stiffness in DM patients. Materials and Methods: There were 200 DM patients in the study population. The LA stiffness value of 0.33 led to the division of the patients into 2 groups. According to these groups, the parameters to predict the development of the LA stiffness were investigated. Results: The patient population’s median age was 54.7 ± 9.4 years, and of them, 105 (52.5% of the popula- tion) were men. Retinopathy was substantially linked with LA stiffness. Interventricular septum thickness (B coefficient: 0.261, 95% CI 0.128; 0.394; P < .001), mitral annular plane systolic excursion (B coefficient: −0.350, 95% CI −0.489; −0.2212; P < 0.001), and retinopathy (B coefficient: 0.644, 95% CI 0.307; 0.983; P < .001) were identified as independent predictors of the progression of LA stiffness by the linear regression model. Conclusion: The results of the current investigation demonstrated a correlation between higher LA stiffness values and the presence of diabetic retinopathy in diabetic patients.Article Citation - WoS: 1G-Quadruplex Enrichment Analysis Reveals Their Role as Intronic Regulatory Elements in Plants(Tubitak Scientific & Technical Research Council Turkey, 2019) Doluca, OsmanG-Quadruplexes, a class of noncanonical but highly stable nucleic acid structures, have the potential to be part of the regulatory mechanism of cells. They can form in the genome where the double-stranded helix is unwound to facilitate formation of a G-quadruplex. The biological significance of these structures is yet to be understood entirely. This work presents a novel approach and investigates common characteristics in the distribution of G-quadruplexes relative to genes in plants through analysis of genomes and gene expressions. The results indicate that G-quadruplex distribution has gone through significant changes with the evolution of higher plants and, for the first tune, that G-quadruplexes enriched at the beginning of introns may have a regulatory role during transcription.Article Citation - WoS: 20Citation - Scopus: 20The Incidence of Pressure Ulcer in Patients on Mechanical Ventilation and Effects of Selected Risk Factors on Pressure Ulcer Development(Tubitak Scientific & Technical Research Council Turkey, 2016) Karayurt, Ozgul; Akyol, Ozay; Kilicaslan, Necmiye; Akgun, Nuray; Sargin, Umran; Kondakci, Melike; Ekinci, HanimBackground/aim: This study aimed to determine the incidence of pressure ulcers in patients on mechanical ventilation and selected risk factors likely to play a role in pressure ulcer development. Materials and methods: The study included 110 patients recruited from an anesthesia critical care unit of a university hospital. Data were collected with a demographic and clinical characteristics form. The form was composed of questions about demographic characteristics and clinical features including diagnosis, duration of mechanical ventilation, general well-being, oxygenation, perfusion, and skin condition. Results: The incidence of pressure ulcer was 15.5%. Duration of mechanical ventilation was longer and the body mass index was higher in patients developing pressure ulcers than in those without pressure ulcers. Additionally, 90.11% of patients with pressure ulcers had edema and 82.35% of patients with pressure ulcers received vasopressin. The patients with pressure ulcers had higher PH levels, lower PaO2 levels, higher PCO2 levels, lower SaO2 levels, and higher urine output. Conclusion: It can be recommended that nurses and other health professionals should be aware of factors playing a role in pressure ulcer development and should be able to conduct appropriate interventions to prevent pressure ulcers.Article Citation - WoS: 17Citation - Scopus: 19Lebesgue-Stieltjes Measure on Time Scales(Scientific Technical Research Council Turkey-Tubitak, 2009) Deniz, Ash; Ufuktepe, ÜnalThe theory of time scales was introduced by Stefan Hilger in his Ph. D. thesis in 1988, supervised Bernd Auldbach, in order to unify continuous and discrete analysis [5]. Measure theory oil time scales was first constructed by Guseinov [4], then further studies were made by Guseinov-Bohner [1], Cabada-Vivero [2] and Rzezuchowski [6]. In this article, we adapt the concept of Lebesgue-Stieltjes measure to time scales. We define Lebesgue-Stieltjes Delta and del-measures and by using these measures, we define ail integral adapted to time scales, specifically Lebesgue-Stieltjes Delta-integral. We also establish the relation between Lebesgue-Stieltjes measure and Lebesgue-Stieltjes Delta-measure, consequently between Lebesgue-Stieltjes integral and Lebesgue-Stieltjes Delta-integral.Article Citation - WoS: 11Citation - Scopus: 14Legendre Wavelet Solution of High Order Nonlinear Ordinary Delay Differential Equations(Scientific Technical Research Council Turkey-Tubitak, 2019) Gumgum, Sevin; Ersoy Ozdek, Demet; Ozaltun, GokceThe purpose of this paper is to illustrate the use of the Legendre wavelet method in the solution of high-order nonlinear ordinary differential equations with variable and proportional delays. The main advantage of using Legendre polynomials lies in the orthonormality property, which enables a decrease in the computational cost and runtime. The method is applied to five differential equations up to sixth order, and the results are compared with the exact solutions and other numerical solutions when available. The accuracy of the method is presented in terms of absolute errors. The numerical results demonstrate that the method is accurate, effectual and simple to apply.Article Citation - WoS: 11Citation - Scopus: 14Making Sense of Turkey's Air and Missile Defense Merry-Go(Center Foreign Policy & Peace Research, 2019) Egeli, SitkiAt some point during 2013, Turkey's political authority began to treat the in-country development and production of long-range air and missile defense systems as a priority. Soon after, they announced their decision to favor a Chinese offer that came complete with licensed production and the promise of technology transfer. Yet, with this decision came NATO's objections and challenges around integration and information security. The 2015 decision to rollback the pro-China decision, and opt instead for the indigenous development of air and missile defense systems (in close conjunction with a foreign technological and industrial partner) was triggered by Turkey's disillusion with the content of China's technology transfer package. Subsequently, this new partner became a team comprising France and Italy; Turkish industry tied itself to this team in developing Europe's next-generation missile defense capability. Then came the Turkish government's 2017 decision to purchase off-the-shelf, standalone S-400 systems from Russia. This decision was an anomaly, and had all the characteristics of a top-down decision cycle running afoul of technical, operational, and industrial criteria. Turkey's political figures have justified the S-400 order by citing the benefits of in-country production, access to technologies, not to mention the West's refusal to sell comparable systems; but these justifications have been refuted by the Russian side and/or in discordant statements by Turkish institutions, authorities, and political figures themselves.Article Citation - WoS: 2Citation - Scopus: 2Model-Based Robust Chaotification Using Sliding Mode Control(Tubitak Scientific & Technical Research Council Turkey, 2014) Kocaoglu, Aykut; Guzelis, CuneytChaos is a complex behavior of dynamical nonlinear systems that is undesirable in most applications and should be controlled; however, it is desirable in some situations and should be generated. In this paper, a robust chaotification scheme based on sliding mode control is proposed for model based chaotification. A continuous time single input observable system is considered such that it is subject to parameter uncertainties, nonlinearities, noises, and disturbances, which are all additive to the input and can be modeled as an unknown function but bounded by a known function. The designed dynamical state feedback control law forces the system to match a reference chaotic system in finite time irrespective of the mentioned uncertainties, noises, and disturbances, as provided by the developed sliding mode control scheme. Simulation results are provided to illustrate the robustness of the proposed scheme against parameter uncertainties and noises. The results are compared with those of other model-based methods and Lyapunov exponents are calculated to show whether the closed-loop control systems exhibit chaotic behavior or not.
