Okan Üniversitesi / Okan University

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Analysis and Implementation of Sensorless Pmsm Drive With Reduced Dc-Link Capacitance Under Parameter Variations
(Ieee, 2024) Sumsek, Reha Ozgur; Calik, Ramazan; Yavuz, Fikri Serkan; Kivanc, Omer Cihan
In AC drives used in heating, ventilation and air-conditioning applications, film capacitors are becoming widespread instead of electrolytic capacitors in DC-link. These drives with reduced capacitor value provide cost and volume advantages. However, dc-link oscillation increases due to the reduced capacity value. These oscillations cause instability, overvoltage and an increase in total harmonic distortion (THD). On the other hand, the winding temperatures of these motors, which operate continuously under rated operating conditions, reach 80 degrees C. The stator resistance and rotor flux value, which change with the increase in temperature, cause these drives, controlled without sensors, to operate even more unstable. In this study, a hybrid approach is proposed to improve the performance of the inverter using a 16 mu F film capacitor at the dc-link and to reduce the THD. The active damping method regulates the inverter output voltage for DC-link voltage stabilization. A permanent magnet synchronous machine (PMSM) sensorless speed control based on stator feedforward voltage estimation and a model reference adaptive system (MRAS) based on a multiparameter estimation algorithm is performed to minimize the effects of parameter variations. As a result of the experimental studies, it is observed that the grid input current complies with the IEC61000-3-2 standard, even under severe parameter variations.
Analysis of the Factors Affecting the Latency Period and Type of Birth in Patients With Preterm Prematur Rupture of Membranes
(Dokuz Eylul Univ inst Health Sciences, 2022) İlhan, Yunus; Kuzu, Ozan; Gozel, Sercan; Yumru, Ayşe Ender
Purpose: To determine the factors associated with the latent period in patients with preterm premature rupture of membranes (PPROM). Material and Methods: 53 patients who applied to our clinic within 1 year and were diagnosed with PPROM and met the inclusion criteria participated in this prospective cross-sectional study. Factors thought to affect the latent period in these patients were examined in terms of delivery time and mode. Results: Latent period; was negatively correlated with dilatation and positively correlated with collum length. The mean latent time of patients with contraction was statistically significantly lower than those without. In another model, gestational week, collum length and birth weight were found to be the most significant factors associated with the latent period. In the latent period groups; Statistically, a significant difference was found in the mean dilatation and collum length. The contraction rate was higher in those with a latency period of 2 days or less. Conclusion: Latent duration is inversely proportional to dilatation and directly proportional to collum length. Uterine contraction is higher in patients with a latency period of fewer than 2 days. Other statistically significant factors related to the latent period are the gestational week and the fetal weight.
Analyzing the Cooperation Between Azerbaijan Naval Forces and Türkiye: Strategic, Operational, and Diplomatic Aspects
(2024) Çora, Hakan; Gürson, Alı Poyraz; Mikail, Elnur Hasan; Çora, Ali Nazmi
This study investigates the historical context and strategic evolution of the naval cooperation between Azerbaijan and Türkiye, highlighting its roots in the early years of Azerbaijan's independence following the dissolution of the Soviet Union. As both nations embarked on building and modernizing their naval capabilities, their partnership became a cornerstone of regional security in the Caspian and Black Seas. The study emphasizes how this cooperation has grown from initial diplomatic ties into a robust military alliance, driven by shared strategic interests and mutual security concerns. The analysis delves into the strategic significance of this partnership, focusing on its role in enhancing the stability of a geopolitically sensitive region. The Caspian Sea, with its vast energy resources, and the Black Sea, a critical maritime zone, both play pivotal roles in regional dynamics. By fostering cooperation in these areas, Azerbaijan and Türkiye not only strengthen their own defense capabilities but also contribute to broader regional security frameworks. Operationally, the collaboration between the two nations' naval forces is characterized by joint exercises, training programs, and the establishment of information-sharing mechanisms. These efforts are designed to improve the interoperability of their naval forces, allowing them to respond more effectively to potential security threats. The study also outlines key areas for future collaboration, including maritime domain awareness, counterterrorism operations, and humanitarian assistance, which could further enhance the strategic partnership. By providing a nuanced and multidimensional analysis, this study aims to offer a comprehensive understanding of the Azerbaijan-Türkiye naval cooperation. It explores the implications of this partnership for regional stability, security, and the balance of power, as well as its potential to influence future maritime and geopolitical developments in the wider region.
Artificial Neural Networks; Definition, Properties and Misuses
(Nova Science Publishers, Inc., 2011) Guresen, E.; Kayakutlu, G.
There are no such clear and good definitions of ANNs in the literature. Many of the definitions refer to the figures instead of well explaining the ANNs. That is why many weighted graphs (as in shortest path problem networks) fit the definition of ANN. This study aims to give a clear definition that will differentiate ANN and graphs (or networks) by referring to biological neural networks. Although there is no input choice limitation or prior assumption in ANN, sometimes researchers compare ANN achievements with the results of other methods using different input data and make comments on these results. This study also gives examples from literature to misuses, unfair comparisons and evaluates the underlying reasons which will guide researchers. © 2011 Nova Science Publishers, Inc. All rights reserved.
Asthmatic Patients: Is Homocysteine an Issue?
(Galenos Publ House, 2024) Keskinel, Ilkay; Gunturk, Arzu; Eryilmaz, Muzeyyen
Objective: Understanding the causes of asthma is crucial for developing new therapeutic modalities. Homocysteine (HCY) is an intermediate in methionine metabolism. Elevated HCY levels may indicate folate and vitamin B12 deficiencies, which are cofactors for the methylation of HCY to methionine. The relationship between hyperHCY mia and atherosclerosis is well-documented, and it is considered a cause of cardiovascular, neurodegenerative, and ocular diseases. HyperHCY mia may also cause atopy and, consequently, asthma. We aimed to evaluate the levels of HCY, vitamin B12, and folic acid in asthmatic patients and healthy adults, as well as to determine whether correlations exist between these levels and lung function, eosinophil counts, total immunoglobulin E (IgE), and eosinophilic cationic protein (ECP) levels in asthmatic subjects. Methods: A total of 142 asthmatic patients and 36 healthy controls were enrolled in the study. Folic acid, vitamin B12, total IgE, ECP, eosinophil percentage, eosinophil counts, and HCY levels were evaluated in both groups. Results: HCY, vitamin B12, and folic acid levels did not significantly differ between patients with asthma and controls. There was a statistically significant positive correlation (at the 0.95 confidence level) between HCY values and forced vital capacity, peak expiratory flow (PEF), and eosinophil counts in patients with asthma. Folic acid levels correlated positively only with PEF%, whereas vitamin B12 levels did not correlate with any functional parameters or atopic markers like IgE and ECP. Conclusion: Should large-scale randomized controlled trials conclusively establish HCY as a causative factor of asthma, metabolic interventions to lower HCY levels using methyl donors could be considered alongside conventional asthma treatments.
Attıtudes of Female Employees In Nutrıtıon of 9 Months-6 Years Old Chıldren In Covıd-19
(Jpms Publ, 2024) Demir, Ibrahim; Onal, Ayse Emel; Ayvaz, Ozkan; Onal, Mehmet Erinc; Onal, Emel Ruya; Yildiz, Sevda Ozel
Background: We aimed to determine the factors affecting the nutritional attitudes of female hospital workers toward their children between 9 months and 6 years of age during the COVID-19 pandemic.Methods: Our study, which is an original article, was conducted with female employees working in the hospital and having children between the ages of 9 months and 6 years. The impact of changes in work and home life during COVID-19 on changes in child care and child nutrition has been questioned. Result: Statistical significance was detected between the scale and questions such as the frequency of anxiety regarding the child's illness during the COVID19 process, the decrease in the child's appetite, changes in the child's eating pattern, the mother's relationship with the environment and social relations, and the child's sleep pattern. Conclusion: A significant relationship was found between inadequate/unbalanced nutrition and educational status and between the reaction to others' opinions sub-dimension and age groups. Moreover, another significant relationship was found between the frequency of anxiety about the child's illness and the scale, and between the change in the child's nutrition pattern and the scale. The COVID-19 pandemic affected the attitudes of female employees towards the nutrition of their children.
Autoimmune Encephalitis and Musicogenic Epilepsy: a Case of Gad65 Antibody-Associated Seizure
(Wiley, 2025) Mohammadi-Asl, Ali; Bahadori, Amir Reza; Sabzgolin, Iman; Davari, Afshan; Razmafrooz, Mohammad; Tafakhori, Abbas; Ranji, Sara
Musicogenic epilepsy (ME) is a rare form of reflex epilepsy with a prevalence of 1 in 10,000,000. Recent research suggests a potential link between ME and autoimmune encephalitis, particularly involving glutamic acid decarboxylase 65-isoform (GAD65) antibodies. A 48-year-old female presented with a one-year history of music-triggered seizures. Her episodes were characterized by an initial aura followed by unresponsiveness and oral automatisms. Electroencephalography revealed abnormalities in the left anterior temporal lobe and temporal leads. Laboratory studies showed positive anti-GAD65 antibodies. The patient was treated with a combination of antiepileptic medication (Lamotrigine) and corticosteroids and intravenous immunoglobulin. This case contributes to the growing evidence supporting an association between ME and autoimmune mechanisms, particularly GAD65 antibody-mediated autoimmunity. It highlights the importance of screening autoimmune factors in ME patients and highlights the need for further research into targeted treatment strategies.
Borçlunun Barter Sistemindeki Hak ve Alacaklarının Haczi
(2024) Topak, Süleyman
Ticari ilişkileri olumsuz etkileyen nakit sıkıntısı ve ekonomik kriz, farklı çözüm yöntemlerinin ortaya çıkmasına sebep olmuştur. Barter sistemi de nakde ihtiyaç duyulmadan sürekliliği sağlamaya yönelik farklı bir ödeme yöntemi olarak kabul edilmiş ve dünya ça- pında uygulanmaya başlamıştır. Parasız ticaret anlayışının hakim ol- duğu barter sistemi, kendine özgü yapıya ve kurallara sahiptir. Bu sistem içerisinde gerçekleşen hukuki işlemlerde resmi para kullanıl- mamakla birlikte sisteme özgü bir değer ve ödeme aracı olarak barter parası uygulaması mevcuttur. Bu yönüyle barter sisteminde oluşan alacaklar, nakit karşılığı olmasa da haczi kabil bir malvarlığı değeri oluşturmaktadır. Bu çalışmada borçlunun barter sisteminde bulunan hak ve alacaklarının haczi, icra hukuku hükümleri gereği farklı yönle- riyle incelenmeye çalışılmıştır.
Capital: an Introduction To the Three Volumes
(Palgrave Macmillan, 2024) Savran, Sungur
Capital: the Book of Communism
(Palgrave Macmillan, 2024) Savran, Sungur
Cardio-Oncology: Cancer and Treatment-Related Cardiotoxicity and Imaging Methods for Assessment of Cardiotoxicity
(Springer Nature, 2024) Guvenc, R.C.; Guler, E.C.; Güvenc, T.S.
Cardio-oncology is a new branch of cardiology that specializes in the diagnosis and treatment of cancer-related and treatment-related cardiac disorders in patients with malignant disease. Being a highly aggressive form of malignancy, esophageal cancer is known to locally invade nearby cardiac structures and great veins, as well as metastasize to the pericardium and myocardium. The chemoradiotherapy regimens used to treat this aggressive form of cancer also expose patients to the risk of treatment-induced cardiac damage and dysfunction. Imaging modalities for the diagnosis and follow-up of cardiac dysfunction range from simple transthoracic echocardiography to advanced imaging modalities such as speckle-tracking echocardiography to cardiac MRI. This chapter summarizes available evidence on the diagnosis and management of cardiotoxicity related to esophageal cancer and its various treatments, as well as imaging modalities used to monitor cancer- and treatment-related cardiac dysfunction. © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2024.
Central nervous system parasites
(Nova Science Publishers, Inc., 2024) Aydinli, A.
When parasitic infections of the Central Nervous System (CNS) are examined, we encounter quite a lot of parasites. Among protozoans, especially free-living amoebae (such as Naegleria, Acanthamoeba, Balamuthia, and Sappinia) have attracted attention in recent years. In addition to these, Microsporidia (Encephalitozoon), Hartmanella, Malaria, Toxoplasma, etc. will appear. It is important that different parasites are identified using different laboratory methods and their treatments are also different. © 2024 Nova Science Publishers, Inc. All rights reserved.
Cephe Kaplama Malzemesi Olarak Alüminyum ve St37 Çelik Metallerinin Tercih Kriterleri
(2024) Karacan, Sena; Yardımlı, Seyhan
Günümüzde teknoloji ve bilim alanındaki gelişmenin en gözle görülür alanlarından bir tanesi de yapı malzemeleri teknolojileridir. İnşaat sektörüne her gün yeni bir yapı malzemesi, alternatifi ve farklı kalitelerde ürün geliştirilerek sunulmaktadır. Mimari yapıların uygulamalarında st37 olarak adlandırdığımız çelik gibi demirli içerikli metallerin yanı sıra bakır, alüminyum, çinko, titanyum, gibi demir dışı metaller veya bu metallerin alaşımları kullanılmaktadır. Bu çalışmada, Yukarıda sözü edilen metal örneklerinden alüminyum metali ve alaşımları ile st37 çelik metalinin cephe malzemesi olarak kullanılmasında tercih kriterlerinin karşılaştırmalı analizleri incelenmiştir. Alüminyum alaşımlarından cephe kaplaması için en sık tercih edilen 1050, 5005 ve 5754 kalite alaşımlara sahip cepheler, st37 olarak adlandırılan karbon çelik cepheler ile karşılaştırılmıştır. Tercih kriterleri üzerine düşünüldüğünde alüminyum ve alaşımlarının genellikle hafiflik, korozyon direnci ve enerji verimliliği tercihinin yüksek olduğu alanlarındaki performansı için uygun bulunduğu, st37 çeliğinin ise içeriği nedeni ile yapısal dayanıklılık ve yüksek sıcaklık, düşük maliyet beklentilerini karşıladığı uygulamalarda kullanıldığı tespit edilmiştir.
Clinical Application of New Possible Biomarkers in the Assessment and Monitoring of Nutritional Status
(Bentham Science Publishers, 2022) Yesilkaya, B.
Nutrition is directly related to human health. It is very critical to determine the nutritional status to prevent or diagnose diseases and create the right treatment plans. The determination of the nutritional status provides an early diagnosis of growth and development retardation such as malnutrition. It also plays a major role in preventing diseases that may be caused by vitamin and mineral deficiencies. It helps in the surveillance of one of the world's most serious health problems, namely “obesity.” Different ways can be used to assess nutritional status. One of the best ways to assess the nutritional and health status is to use biomarkers. A biomarker is a substance whose detection indicates a specific disease state or a response to a therapeutic intervention. Biomarkers are used to detect nutrient consumption and deficiencies as early as possible, enabling early intervention for metabolic problems. Biomarkers also allow the visualization of diseases that a person might develop or potentially have with a sample, such as blood, tissue, and urine, from the person. Health interventions such as nutritional advice will preserve health or promote rapid recovery. In this chapter, the topic of biomarkers related to nutrition and nutrient deficiencies is discussed. The existence of new possible biomarkers is also reviewed. © 2022, Bentham Books imprint.
Comparative Analysis of Transaction Performance in Different Virtualization Environments
(Istanbul Univ, 2024) Candemir, Ali Ihsan; Incereis, Nilgun
Virtualization technologies are increasing in importance day by day. The selection of virtualization software is an important factor to realize efficient use of physical hardware. In this study, the Ubuntu 22.04 LTS operating system was run on VirtualBox, VMware, and Docker, which are widely used virtualization software. Then, the Tiobench, Compress-7zip, C-ray, Smallpt, Tachyon, and OSBench tests were performed on the Ubuntu operating system with the Phoronix Test Suite software, and the test results were analyzed and compared. The results demonstrate that Docker outperformed the other virtualization technologies, although not in every test. Owing to its rapid deployment and efficient use of resources, Docker is suitable for applications that require agility and scalability. However, traditional virtualization technologies, such as VMware, may be more suitable for applications that require high security and extensive resource management. In addition, this study provides information that can guide users in selecting virtualization software.
Comparison of Posterior and Antero-Lateral Renal Tumors in Retroperitoneal Laparoscopic Partial Nephrectomy: a Propensity Score Matching Analysis
(Codon Publications, 2023) Anil, Hakan; Yildiz, Ali; Guzel, Ahmet; Akdemir, Serkan; Karamik, Kaan; Arslan, Murat
This study aimed to compare the antero-lateral and posterior localized renal masses in laparoscopic partial nephrectomy with the retroperitoneal approach in terms of operative, functional, and oncological outcomes. Patients who underwent retroperitoneal laparoscopic partial nephrec-tomy by a single surgeon between January 2013 and January 2021 were included in the study. A one-to-one propensity score matching (PSM) analysis was conducted to obtain two balanced groups. The patients were divided into two groups as posterior and antero-lateral according to the localization of the mass. A total of 239 patients were included in the PSM analysis, with 65 patients allocated to each group. The mean operative time was 79.2 & PLUSMN; 11.2 min in the posterior group, while it was 90.0 & PLUSMN; 11.6 min in the antero-lateral group (P < 0.001). Warm ischemia time was 15.9 & PLUSMN; 2.4 min in the posterior group and 18.6 & PLUSMN; 2.7 min in the antero-lateral group (P < 0.001). The median decrease in eGFR at 1 year was 4.8 (IQR, 2.9-6.9) mL/min in the posterior group and 5.0 (IQR, 2.8-11) mL/min in the antero-lateral group (P = 0.219). The warm isch-emia time and clamping technique were found to be significant factors for predicting eGFR change after surgery (13:0.693, 95% CI: 0.39-0.99, P < 0.001; 13:6.43, 95% CI: 1.1-11.7, P = 0.017, respectively). We report that retroperitoneal laparoscopic partial nephrectomy provided longer warm ischemia and operative time for antero-lateral renal masses than posterior masses. However, long-term oncological and functional results were similar for both localizations.
Confusions Concerning Sraffa (and Marx): Reply To Critics
(Palgrave Macmillan, 2024) Savran, Sungur
The Controversy Between the Neo-Ricardians and the Marxists
(Palgrave Macmillan, 2024) Savran, Sungur
COVID-19 Seroprevalence in Cirrhotic Patients and Effect of COVID-19 Infection on Liver Cirrhosis by Clinical Form in the Postinfectious Period
(Galenos Publ House, 2024) Oenal, Ugur; Oezbey, Dogukan; Bakkaloglu, Oguz Kagan; Eskazan, Tugce; Kurt, Enes Ali; Hatemi, Ali Ibrahim; Sonsuz, Abdullah
Introduction: There are very few studies demonstrating the seroprevalence of coronavirus disease-2019 (COVID-19) in patients with cirrhosis worldwide and in Turkey. This study aimed to investigate the seroprevalence of COVID-19 in patients with cirrhosis and its effect on liver cirrhosis by clinical form in the postinfectious period. Methods: The study included 174 patients with cirrhosis. Patients with COVID-19 were identified using anti-severe acute respiratory syndrome-coronavirus-2-immunoglobulin G (SARS-CoV-2-IgG) and COVID-19 polymerase chain reaction assays and were divided into symptomatic and asymptomatic groups. The last polyclinic records of the patients before infection or testing were determined as 1 st examination and the date of blood collection for anti-SARS-CoV-2-IgG was determined as the 2 nd examination. Examination findings and liver tests of the patients in both periods were recorded; Child-Pugh Score (CPS) and Model for End Stage Liver Disease (MELD)-Na scores were calculated. Additionally, patients were evaluated for newly developed hepatic decompensation. Results: The seropositivity of anti-SARS-CoV-2-IgG was detected in 35.6% of our patients, and the rate of those who had symptomatic COVID-19 infection was 23.6%, whereas the rate of those who had asymptomatic infection was 12%. There was no significant difference in liver tests, CPS, and MELD-Na scores before and after COVID-19 infection between symptomatic and asymptomatic patients, and new decompensation was found in 9.6% of patients with COVID-19 infection. Conclusion: The incidence of COVID-19 among patients with liver cirrhosis is notably high. Although high decompensation rates were reported in the acute phase of the disease, such rates were not observed in the postinfectious period. Ultimately, our results indicated no significant difference in the course of existing liver disease according to clinical form.
Critique of Political Economy
(Palgrave Macmillan, 2024) Savran, Sungur

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