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Publication Open Access A benevolent angel with blue eyes(Türk Kütüphaneciler Derneği, 2019) Ergün, Canan; Other; Suna Kıraç LibraryI met Professor Dr. Meral Alpay on my first day at Istanbul University, Department of Librarianship. I tried to tell my memory of this first day that I met with Professor Dr. Meral Alpay. / İstanbul Üniversitesi Kütüphanecilik Bölümünü kazanıp, okula başladığım ilk gün Prof. Dr. Meral Alpay hocam ile tanışma anımı anlatmaya çalıştım.Publication Open Access A class of Banach algebras whose duals have the Schur property(TÜBİTAK, 1999) Mustafayev, H.; Department of Mathematics; Ülger, Ali; Faculty Member; Department of Mathematics; College of SciencesCall a commutative Banach algebra A a γ-algebra if it contains a bounded group Λ such that aco(Λ) contains a multiple of the unit ball of A. In this paper, first by exhibiting several concrete examples, we show that the class of γ-algebras is quite rich. Then, for a γ-algebra A, we prove that A* has the Schur property iff the Gelfand spectrum Σ of A is scattered iff A* = ap(A) iff A* = Span(Σ).Publication Open Access A combined VBM and DTI study of schizophrenia: bilateral decreased insula volume and cerebral white matter disintegrity corresponding to subinsular white matter projections unlinked to clinical symptomatology(Aves, 2017) Ulaşoğlu-Yıldız, Çiğdem; Aslan, Selçuk; Talı, Erhan Turgut; N/A; N/A; Onay, Aslıhan; Eser, Hale Yapıcı; Faculty Member; School of Medicine; N/A; 134359PURPOSE: Grey matter and white matter changes within the brain are well defined in schizophrenia. However, most studies focused on either grey matter changes or white matter integrity separately; only in limited number of studies these changes were interpreted in the same frame. In addition, the relationship of these findings with clinical variables is not clearly established. Here, we aimed to investigate the grey matter and white matter changes in schizophrenia patients and exhibit the relation of these imaging findings with clinical variables. METHODS: A total of 20 schizophrenia patients and 16 matched healthy controls underwent magnetic resonance imaging to investigate the grey matter and white matter alterations that occur in schizophrenia patients using voxel-based morphometry (VBM) and whole brain voxel-wise analysis of diffusion tensor imaging (DTI) parameters with SPM8, respectively. While the preprocessing steps ofVBM were performed with the default parameters of VBM8 toolbox, the preprocessing steps of DTI were carried out using FSL. Additionally, VBM results were correlated with clinical variables. RESULTS: Bilateral insula showed decreased grey matter volume in schizophrenia patients compared with healthy controls (P < 0.01). The opposite contrast did not show a significant difference. Psychiatric scores, duration of illness, and age were not correlated with the decreased grey matter volume of insula in schizophrenia patients. DTI analysis revealed a significant increase in mean, radial, and axial diffusivity, mainly of the fibers of bilateral anterior thalamic radiation and superior longitudinal fasciculus with left predominance, which intersected with bilateral subinsular white matter (P < 0.05). CONCLUSION: Our findings suggest that insula may be the main affected brain region in schizophrenia, which is also well supported by the literature. Our results were independent of disease duration and schizophrenia symptoms. White matter alterations were observed within bilateral anterior thalamic radiation and superior longitudinal fasciculus that intersects with subinsular white matter. Studies with larger sample sizes and more detailed clinical assessments are required to understand the function of insula in the neurobiology of schizophrenia.Publication Open Access A diagnostic challenge: risk factors and surgical treatment of laryngeal chondroradionecrosis(Aves, 2022) Başaran, Bora; Doruk, Can; Çaytemel, Berkay; Şen, Cömert; Aslan, İsmet; Ünsaler, Selin; School of Medicine; 167909Objectives: thirteen cases of laryngeal chondroradionecrosis unresponsiveto conservative treatment and treated with laryngectomy were presented with an analysis of possible risk factors. Methods: retrospective analysis of 13 patients operated on for chondroradionecrosis was made. Characteristics of the primarytumor, chondroradionecrosis grade, number of biopsies needed to rule out recurrence, and laryngectomy indications were analyzed. The possible predisposing factors such as alcohol and tobacco use and other major chronic diseases were investigated. Results: all of the patients had a history of smoking. The most common comorbidity was hypertension (46.2%), followed by chronic obstructive pulmonary disease (23.1%). The onset of symptoms was documented within the 10 monthsfollowing the radiation therapy in 12 of the patients (93.3%) and 12 years after the primary radiation therapy in 1 patient. Asthe most common symptom, fetor oris was observed in all of the patients, followed by dysphagia (69.2%), hoarseness (61.5%), pain (53.8%), dyspnea (46.2%), and necrotic fistula formation in the anterior neck (15.4%) consecutively. Tumor suspicion (84.6%) was the most common indication for laryngectomy followed by chronic aspiration or feeding disorder (61.5%). Twelve patients were treated with total and 1 with supraglottic laryngectomy. Pectoralis major muscle flap was used in all of the patients for pharyngeal reconstruction or protection against salivary fistula. Conclusion: diagnosis of chondroradionecrosis is challenging, and tumor recurrence should always be kept in mind. Patients must be informed about the possibility of chondroradionecrosis complications including laryngectomy. Introduction: chondroradionecrosis is a rare and the most severe complication of radiation therapy for laryngeal carcinoma.Publication Open Access A new risk-scoring system for colorectal cancer and polyp screening by Turkish Colorectal Cancer and Polyp Study Group(Aves, 2022) Erdem, L.; Akbal, E.; Koçak, E.; Tucer, D.; Üçbilek, E.; Uyanıkoğlu, A.; Dolapçıoğlu, C.; Şirin, G.; Alkım, H.; Soylu, A.; Doğanay, L.; Kürbüz, A.K.; Özdil, K.; Alagözlü, H.; Erürker Öztürk, T.; Sezikli, M.; Adalı, G.; Çoban, M.; Hülagü, S.; Değertekin, H.; Atasoy, A.; Akyüz, F.; Gaffarlı, İ.; Saruç, M.; Altıntaş, E.; Sezgin, O.; Tözün N.; Ahıshalı, Emel; School of MedicineBackground: colorectal cancer is one of the most commonly diagnosed types of cancer worldwide. An early diagnosis and detection of colon cancer and polyp can reduce mortality and morbidity from colorectal cancer. Even though there are a variety of options in screening tests, the question remains on which test is the most effective for the early detection of colorectal cancer. In this prospective study, we aimed to develop a simple, useful, effective, and reliable scoring system to detect colon polyp and colorectal cancer. Methods: we enrolled 6508 subjects over the age of 18 from 16 centers, with colonoscopy screening. The age, smoking status, alcohol consumption, body mass index, polyp incidence, polyp size, number and localization, and pathologic findings were recorded. Results: the age, male gender, obesity, smoking, and family history were found as independent risk factors for adenomatous polyp. We have developed a new scoring system which can be used for these factors. With a score of 4 or above, we found the following: sensitivity 81%, specificity 40%, positive predictive value 25.68%, and negative predictive value 89.84%, for adenomatous polyp detection; and sensitivity 96%, specificity 39%, positive predictive value 3.35%, negative predictive value 99.29%, for colorectal cancer detection. Conclusion: even though the first colorectal cancer screening worldwide is generally performed for individuals over 50 years of age, we recommend that screening for colorectal cancer might begin for those under 50 years of age as well. Individuals with a score ? 4 must be included in the screening tests for colorectal cancer.Publication Open Access A nonminimally coupled, conformally extended Einstein-Maxwell theory of pp-waves(TÜBİTAK, 2020) Department of Physics; Dereli, Tekin; Şenikoğlu, Yorgo; Researcher; Department of Physics; Graduate School of Sciences and Engineering; College of Sciences; 201358; N/AA nonminimal coupling of Weyl curvatures to electromagnetic fields is considered in Brans-Dicke-Maxwell theory. The gravitational field equations are formulated in a Riemannian spacetime where the spacetime torsion is constrained to zero by the method of Lagrange multipliers in the language of exterior differential forms. The significance and ramifications of nonminimal couplings to gravity are examined in a pp-wave spacetime.Publication Open Access A practitioner’s guide to handling irregularities resulting from the 2014 revisions of the Turkish Household Labor Force Survey(Boğaziçi Üniversitesi İktisadi ve İdari Bilimler Fakültesi, 2021) Poyraz, Meltem; Department of Economics; Demirci, Murat; Faculty Member; Department of Economics; College of Administrative Sciences and Economics; 272082We document the implications of the 2014 revisions to the Turkish Household Labor Force Survey and offer guidance on how to handle the irregularities in population and unemployment statistics that resulted from two particular revisions. First, new population projections were adopted to assign survey weights. Second, a narrower definition of unemployment was adopted. We propose methods to adjust the survey weights for the pre-2014 period in order to discern changes in population statistics by age groups and regions without interruption over time and to calculate the unemployment rates according to both broader and narrower definitions since 2004. / Bu çalışmada TÜİK Hanehalkı İşgücü Anketi’ninde 2014 yılında yapılan düzenlemelerden kaynaklanan bazı sonuçları bulguluyor, nüfus ve işsizlik istatistiklerinde yapılan revizyonların özellikle ikisinden kaynaklanan sorunların nasıl ele alınması gerektiği hakkında yol gösteriyoruz. İlk revizyon, anket ağırlıklarının dayandırıldığı yeni nüfus projeksiyonlarının kabul edilmesidir. İkincisi ise, dar tanımlı bir işsizlik tanımına geçilmesidir. Bu çalışmada 2014 öncesindeki anket ağırlıklarını nüfus istatistiklerinde yaş bazında ve bölgesel olarak kopma olmayacak şekilde yeniden ayarlamak ve işsizlik oranlarını geniş ve dar tanımlı olarak 2004 yılından itibaren hesaplamak için yöntemler öneriyoruz.Publication Open Access A rabbit model of avascular necrosis of femoral head using surgical trauma and systemic steroids(Galenos Yayınevi, 2020) Özben, Hakan; School of MedicineObjective: avascular necrosis of the femoral head (ANFH) is a disease caused by the diminished circulation of the femoral head. The incidence of the disease is increasing and it has heavy socioeconomical burden. Animal models are indispensable for the development of new treatments for bone avascular necrosis. There is not any reliable animal model for simulating the early stages of femoral head osteonecrosis. The aim of this study is to present an animal model of femoral head osteonecrosis induced by systemic steroid use combined with surgery. Methods: six New Zealand White rabbits were divided into 3 groups. Each group contained 4 femoral heads. For the induction of osteonecrosis, every hip underwent surgical dislocation followed by cauterization of extraperiosteal vessels around the femoral head and ligamentum teres resection. A single dose intramuscular steroid was administered to each rabbit. Rabbits were sacrificed at 2nd, 4th and 6th weeks and femoral heads were sent to histological evaluation. Results: the femoral heads showed typical signs of avascular necrosis at the end of 2nd week. In addition to osteocyte loss and marrow necrosis, there was also new osteoblast formation at the end of 4th week. At the end of 6th week, epiphyseal new bone formation next to large necrotic areas were visible. Conclusion: these results suggest that the single steroid administration combined with hip luxation and cauterization of neck vessels may create femoral head osteonecrosis in rabbits in a repeatable and reliable manner. This model can be presented as an alternative model for the new studies on the treatment of femoral head avascular necrosis in the early stage. / Amaç: femur başı avasküler nekrozu (FBAN), femur başının kanlanmasındaki azalmadan kaynaklanan, görülme sıklığı giderek artan ve ağır sosyo-ekonomik etkileri olan bir hastalıktır. Hayvan modelleri, kemiklerdeki avasküler nekrozlar için yeni tedavi yöntemlerinin oluşturulmasında vazgeçilmezdir. Halen, erken dönem FBAN’yi simüle edebilen güvenilir bir hayvan modeli yoktur. Bu çalışmanın amacı, cerrahi ve sistemik steroid kombinasyonu ile tavşanda FBAN modeli oluşturmaktır. Yöntemler: altı Yeni Zelanda beyaz tavşanı 3 gruba ayrıldı. Her grup 4 femur başı içermekteydi. FBAN oluşturmak için her kalçaya cerrahi olarak dislokasyon, femur boynu periosteal damarların koterizasyonu ve ligamentum teres eksizyonu yapıldı. Sonrasında her tavşana tek doz intramusküler steroid uygulandı. Gruplardaki hayvanlar sırasıyla 2., 4. ve 6. haftalarda sakrifiye edildi ve tüm femur başları rezeke edildi. Femur başları histolojik olarak avasküler nekroz bulguları açısından değerlendirildi. Bulgular: ikinci haftanın sonunda incelenen femur başlarında tipik histolojik avasküler nekroz bulguları mevcut idi. Dördüncü hafta sonunda alınan örneklerin yapılan histolojik değerlendirmelerinde osteosit kaybı ve kemik iliği nekrozuna ek olarak osteoblast oluşumları görüldü. Altıncı hafta sonunda yapılan incelemelerde epifizyel alanlarda geniş kemik iliği nekrozlarına ek olarak yeni kemik oluşumları görüldü. Sonuç: bu sonuçlar, femur başı luksasyonu ve koterizasyonu ile tek doz steroid uygulamasının tavşanlarda güvenilir ve tekrarlanabilir şekilde femur başı nekrozu oluşturduğunu göstermektedir. Bu model, femur başı osteonekrozlarının erken dönem tedavisi araştırmalarında kullanılabilecek bir seçenek olarak sunulabilir.Publication Open Access A systematic and efficient input selection method for artificial neural networks using mixed-integer nonlinear programming(Konya Teknik Üniversitesi, 2022) Şıldır, Hasan; Department of Chemical and Biological Engineering; Aydın, Erdal; Faculty Member; Department of Chemical and Biological Engineering; College of Engineering; 311745Selection of input variables of the empirical models has vital effect on the prediction performance, reduced overfitting and reduced computational load. Various trials and error and sequential methods in the literature to deal with input selection for artificial neural networks (ANNs). However, these methods are not considered as automatic and systematic. This study proposes a novel and efficient mixed integer nonlinear programming-based approach to handle optimal input selection and the ANN training simultaneously for classification problems. Such selection uses binary (0-1) variables to represent the presence of the input variables and trains traditional continuous network weights simultaneously. Two classification case studies are given to demonstrate the advantages by using widely used data sets and statistical measures. The first data set is related to the characterization of the type of a tumor related to breast cancer, the second data set is about predicting the type of a biotechnological product using different features, the last one is related to heart failure prediction. Results show that better test performance can be achieved with optimally selected inputs, resulting in reduced overfitting. The proposed approach delivers a significant advantage during the design and training of the ANNs and is also applicable to other empirical models. / Ampirik modellerin girdi değişkenlerinin seçimi, tahmin performansı, azaltılmış fazla uydurma ve hesaplama yükünün azaltılması üzerinde önemli etkiye sahiptir. Literatürde yapay sinir ağları (YSA) için girdi seçimi ile ilgili çeşitli deneme yanılma yöntemleri mevcuttur ancak bu metodlar sistematik ve otomatik olarak kabul edilmemektedir. Bu çalışma, sınıflandırma problemleri için optimal girdi seçimi ve YSA eğitimini aynı anda ele almak için yeni ve verimli bir karma tamsayılı doğrusal olmayan programlama tabanlı bir yaklaşım önermektedir. Bu seçim, girdi değişkenlerinin varlığını temsil etmek için ikili (0-1) değişkenleri kullanır ve geleneksel sürekli ağ ağırlıklarını veya parametrelerini aynı anda eğitir. Yaygın olarak kullanılan veri setleri ve istatistiksel ölçümler kullanarak avantajları göstermek amacıyla üç sınıflandırma vaka çalışması sunulmuştur. Birinci veri seti meme kanseri ile ilgili tümörün tipin-in karakterizasyonu ile ilgili olup, ikinci veri seti ise farklı özellikler kullanılarak bir biyoteknolojik ürünün tipinin tahmin edilmesi ile ilgilidir, son veri seti ise kalp sağlığı ile ilgilidir. Sonuçlar, optimal olarak seçilen girdiler ile düşük fazla uydurma sayesinde daha iyi test performansının elde edilebileceğini göstermektedir. Önerilen yaklaşım, YSA'ların tasarımı ve eğitimi sırasında önemli bir avantaj sağlar ve diğer ampirik modellere de uygulanabilir.Publication Open Access Aberrant methylation profile and microsatellit instability in Turkish sporadic colorectal carcinoma(Galenos Yayınevi, 2019) Ekmekçi, Cumhur Gökhan; Güllüoğlu, Mine; Dizdaroglu, Ferhunde; Özbek, Uğur; N/A; Kapran, Yersu; Faculty Member; School of Medicine; 168101Objective: genomic DNA obtained from paraffin blocks of the intended colorectal cancer cases was evaluated for promoting colorectal cancer by investigating the promoter methylation of 6 different gene promoter regions and microsatellite instability. Methods: DNA was isolated from the paraffin tissue of 76 sporadic colorectal cancer patients by cross sections from the areas determined to be tumorous. The methylation specific PCR (MS-PCR) method was used for these DNA samples fo rmethlylation studies in promoter region of six different APC, hMLH1, p16INK4A, p15, p73 and DAPK1 genes. In the same samples, the presence of microsatellite instability (MSI). Results: the fequencey of methylation was 24% for hMLH1, 31.5% for APC, 19.6% for DAPK1, 42.8% for p16, 30% for p15, 17% for p73. We calculated a methylation index (MI=ratio between the number of genes methylated and the number of genes analyzed). MI was ranged from 0-0.83, with an average of 0.271 corresponding to 1.6 genes/sample and median was 0.225 and there were 15 samples which doesn't methylated in any loci. We analysed MSI in C-kit (21%), hMSH2 (18%) and APC (15%), microsatellite region. Conclusion: we observed APC methylation was common then the other population for Turkish patient. P16 was the most commenest methylated loci among the 6 of gene and it seems storongly related with female patients. P73 was releated with left colorectal cancer and additionally it was related with the MSI.