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Permanent URI for this collectionhttps://hdl.handle.net/20.500.14411/22
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Article Citation - WoS: 12Citation - Scopus: 16A two-step machine learning approach to predict S&P 500 bubbles(Taylor & Francis Ltd, 2020-09-22) Kabran, Fatma Basoglu; Unlu, Kamil Demirberk; Başoğlu Kabran, FatmaIn this paper, we are interested in predicting the bubbles in the S&P 500 stock market with a two-step machine learning approach that employs a real-time bubble detection test and support vector machine (SVM). SVM as a nonparametric binary classification technique is already a widely used method in financial time series forecasting. In the literature, a bubble is often defined as a situation where the asset price exceeds its fundamental value. As one of the early warning signals, prediction of bubbles is vital for policymakers and regulators who are responsible to take preemptive measures against the future crises. Therefore, many attempts have been made to understand the main factors in bubble formation and to predict them in their earlier phases. Our analysis consists of two steps. The first step is to identify the bubbles in the S&P 500 index using a widely recognized right-tailed unit root test. Then, SVM is employed to predict the bubbles by macroeconomic indicators. Also, we compare SVM with different supervised learning algorithms by usingk-fold cross-validation. The experimental results show that the proposed approach with high predictive power could be a favourable alternative in bubble prediction.Review Citation - WoS: 22Citation - Scopus: 22The Effect of Gender on Disease Activity and Clinical Characteristics in Patients With Axial Psoriatic Arthritis(Taylor & Francis Ltd, 2020-09-17) Nas, Kemal; Kilic, Erkan; Tekeoglu, Ibrahim; Keskin, Yasar; cevik, Remzi; Sargin, Betul; Tuncer, TirajeObjectives In this study, we aimed to evaluate the effect of gender on clinical findings, disease activity, functional status and quality of life in patients with axial involvement in Turkey. Methods Patients with PsA who met the CASPAR classification criteria were enrolled consequently in this cohort. Turkish League Against Rheumatism (TLAR)-Network was formed with the participation of 25 centres. The demographic variables, fatigue, diagnostic delay, the beginning of peripheral arthritis, enthesitis, dactylitis and spine involvement, inflammatory low back pain, BASFI, HAQ, HAQ-s, visual analogue scale-pain (VAS-pain), anxiety, depression and disease activity parameters (ESR, DAS28, BASDAI) were recorded. Axial involvement was assessed according to clinical and radiological data according to modified New York (MNYC) or Assessment of SpondyloArthritis international Society (ASAS) criteria. Results A total of 1018 patients with PsA were included in this study. Of the 373 patients with axial involvement, 150 were male (40.2%) and 223 (59.8%) were female. Spondylitis was detected in 14,7% of men and 21,9% of women in all patients. Pain score (VAS) (p < .002), fatigue (p < .001), ESR (p < .001), DAS28 (p < .001), BASDAI score (p < .001), PsAQoL (p < .001), HAQ score (p < ,01), HAQ-S score (p < .001), anxiety (p < .001), depression (p < .024), FACIT (p < .001) and FiRST (p < .001) scores were statistically significantly worse in women than males with axial PsA. However, quality of life was better (p < .001) and PASI score (p < .005) were statistically worse in male patients than in female patients with axial involvement. Conclusion This study has shown that the burden of disease in axial PsA has significant difference between genders. Disease activity, physical disability, functional limitation, depression and anxiety scores were higher in female patients, while quality of life were better and PASI score were higher in male patients. Therefore, we suggest that new strategies should be developed for more effective treatment of axial PsA in female patients.Article Citation - WoS: 13Citation - Scopus: 13Higher Rates of Cefiderocol Resistance Among Ndm Producing <i>klebsiella</I> Bloodstream Isolates Applying Eucast Over Clsi Breakpoints(Taylor & Francis Ltd, 2023-06-30) Isler, Burcu; Vatansever, Cansel; Ozer, Berna; Cinar, Gule; Aslan, Abdullah Tarik; Falconer, Caitlin; Harris, Patrick N. A.BackgroundCefiderocol is generally active against carbapenem-resistant Klebsiella spp. (CRK) with higher MICs against metallo-beta-lactamase producers. There is a variation in cefiderocol interpretive criteria determined by EUCAST and CLSI. Our objective was to test CRK isolates against cefiderocol and compare cefiderocol susceptibilities using EUCAST and CLSI interpretive criteria.MethodsA unique collection (n = 254) of mainly OXA-48-like- or NDM-producing CRK bloodstream isolates were tested against cefiderocol with disc diffusion (Mast Diagnostics, UK). Beta-lactam resistance genes and multilocus sequence types were identified using bioinformatics analyses on complete bacterial genomes.ResultsMedian cefiderocol inhibition zone diameter was 24 mm (interquartile range [IQR] 24-26 mm) for all isolates and 18 mm (IQR 15-21 mm) for NDM producers. We observed significant variability between cefiderocol susceptibilities using EUCAST and CLSI breakpoints, such that 26% and 2% of all isolates, and 81% and 12% of the NDM producers were resistant to cefiderocol using EUCAST and CLSI interpretive criteria, respectively.ConclusionsCefiderocol resistance rates among NDM producers are high using EUCAST criteria. Breakpoint variability may have significant implications on patient outcomes. Until more clinical outcome data are available, we suggest using EUCAST interpretive criteria for cefiderocol susceptibility testing.Article Citation - WoS: 18Citation - Scopus: 18Validity and Reliability of 6-Minute Pegboard and Ring Test in Patients With Asthma(Taylor & Francis Ltd, 2021-05-31) Calik-Kutukcu, Ebru; Tekerlek, Haluk; Bozdemir-Ozel, Cemile; Karaduz, Beyza Nur; Cakmak, Aslihan; Inal-Ince, Deniz; Karakaya, GulObjective The 6-minute pegboard and ring test (6PBRT) is a test of upper-extremity functional capacity designed for and validated in chronic obstructive pulmonary disease. The aim of this study was to evaluate the validity and reliability of the 6PBRT in asthma patients. Methods Thirty-four adults (30 women, 4 men) with well-controlled asthma were included. Unsupported upper-extremity exercise capacity was assessed using 6PBRT, maximal arm exercise capacity using an arm ergometer, handgrip strength using a hand dynamometer, activities of daily living with the London Chest Activities of Daily Living Scale (LCADL), Milliken ADL scale (MAS) and health-related quality of life using the Asthma Quality of Life Questionnaire (AQLQ) and Health Assessment Questionnaire Disability Index (HAQ-DI). Results The 6PBRT showed moderate to excellent test-retest reliability with an intraclass correlation coefficient (ICC) value of 0.872 [95% confidence interval (CI) 0.702-0.941]. The 6PBRT was reproducible according to Bland-Altman analysis, with upper and lower limits of agreement of 53.51 and -25.08 rings moved, respectively. The 6PBRT score was significantly correlated with maximum workload (r = 0.514, p = 0.002) achieved in the arm ergometer test, change in dyspnea during 6PBRT (r = -0.402, p = 0.020), LCADL-self-care (r = -0.364, p = 0.037), MAS total (r = 0.483, p = 0.005), AQLQ-symptom domain (r = 0.420, p = 0.026) and HAQ-DI total scores (r = -0.390, p = 0.025). Conclusions The 6PBRT can be used as a valid and reliable test to evaluate functional arm exercise capacity in patients with well-controlled asthma.Article Citation - WoS: 2Citation - Scopus: 2Estimation in the Partially Nonlinear Model by Continuous Optimization(Taylor & Francis Ltd, 2020-12-23) Yerlikaya-Ozkurt, Fatma; Taylan, Pakize; Tez, MujganA useful model for data analysis is the partially nonlinear model where response variable is represented as the sum of a nonparametric and a parametric component. In this study, we propose a new procedure for estimating the parameters in the partially nonlinear models. Therefore, we consider penalized profile nonlinear least square problem where nonparametric components are expressed as a B-spline basis function, and then estimation problem is expressed in terms of conic quadratic programming which is a continuous optimization problem and solved interior point method. An application study is conducted to evaluate the performance of the proposed method by considering some well-known performance measures. The results are compared against parametric nonlinear model.Article Citation - WoS: 19Citation - Scopus: 19A New Outlier Detection Method Based on Convex Optimization: Application To Diagnosis of Parkinson's Disease(Taylor & Francis Ltd, 2020-12-23) Taylan, Pakize; Yerlikaya-Ozkurt, Fatma; Bilgic Ucak, Burcu; Weber, Gerhard-WilhelmNeuroscience is a combination of different scientific disciplines which investigate the nervous system for understanding of the biological basis. Recently, applications to the diagnosis of neurodegenerative diseases like Parkinson's disease have become very promising by considering different statistical regression models. However, well-known statistical regression models may give misleading results for the diagnosis of the neurodegenerative diseases when experimental data contain outlier observations that lie an abnormal distance from the other observation. The main achievements of this study consist of a novel mathematics-supported approach beside statistical regression models to identify and treat the outlier observations without direct elimination for a great and emerging challenge in humankind, such as neurodegenerative diseases. By this approach, a new method named as CMTMSOM is proposed with the contributions of the powerful convex and continuous optimization techniques referred to as conic quadratic programing. This method, based on the mean-shift outlier regression model, is developed by combining robustness of M-estimation and stability of Tikhonov regularization. We apply our method and other parametric models on Parkinson telemonitoring dataset which is a real-world dataset in Neuroscience. Then, we compare these methods by using well-known method-free performance measures. The results indicate that the CMTMSOM method performs better than current parametric models.Article Citation - WoS: 9Citation - Scopus: 7Identifying the Cycles in Covid-19 Infection: the Case of Turkey(Taylor & Francis Ltd, 2022-01-31) Akdi, Yilmaz; Karamanoglu, Yunus Emre; Unlu, Kamil Demirberk; Bas, Cem; Emre Karamanoğlu, YunusThe new coronavirus disease, called COVID-19, has spread extremely quickly to more than 200 countries since its detection in December 2019 in China. COVID-19 marks the return of a very old and familiar enemy. Throughout human history, disasters such as earthquakes, volcanic eruptions and even wars have not caused more human losses than lethal diseases, which are caused by viruses, bacteria and parasites. The first COVID-19 case was detected in Turkey on 12 March 2020 and researchers have since then attempted to examine periodicity in the number of daily new cases. One of the most curious questions in the pandemic process that affects the whole world is whether there will be a second wave. Such questions can be answered by examining any periodicities in the series of daily cases. Periodic series are frequently seen in many disciplines. An important method based on harmonic regression is the focus of the study. The main aim of this study is to identify the hidden periodic structure of the daily infected cases. Infected case of Turkey is analyzed by using periodogram-based methodology. Our results revealed that there are 4, 5 and 62 days cycles in the daily new cases of Turkey.