Correcting the Echo-Planar Image Encoding Imperfections in Arterial Spin Labeling MRI using Magnetic Field Monitoring and Gradient Impulse Responses

Arteryel spin etiketleme (ASE) tabanlı perfüzyon manyetik rezonans görüntüleme tekniği çok düşük sinyal-gürültü oranına sahiptir. Dolaysıyla bu yöntem k-uzayı verisinin hızlı bir şekilde toplanmasını gerektirir. Bu genellikle veri-okuma sekansı olarak gradyan-echo EPI kullanılarak sağlanır. Bu hızlı k-uzayı geçişi, gradyanların sistem kapasitesinin limitlerinde çalışmasını ve veri toplama sırasında çok hızlı yön değiştirmelerini gerektirir ve bu gereklilik gradyan alanlarında sapmalara sebep olur. Gradyan alanlarının zamana göre değişimlerinde meydana gelen bu sapmalar görüntü oluşturmada önemli hatalar ortaya çıkmasına neden olur. Bu çalışmada, gradyan alanlarının oluşumları dinamik bir manyetik alan kamerası ile doğrudan ölçülerek ASE görüntüleri asıl gradyan alanları kullanılarak yeniden oluşturulmuştur. Bununla beraber, gradyan sisteminin doğrusal ve zamanla-değişmez bir sistem olduğu varsayılarak gradyan dürtü fonksiyonu (GDF) tanımlanabilir. Tanımlanan GDF, bir defaya mahsus bir kalibrasyon yöntemi olarak asıl gradyan şekillerinin kestirimlerinin yapılmasında ve bu kestirimler yardımı ile görüntü oluşturulmada kullanılabilir. Ek olarak ASE görüntüleri, GDF ile kestirimi yapılmış gradyan alanları kullanılarak yeniden oluşturulmuştur. Gradyan alanı sapmalarının nicel perfüzyon manyetik rezonans görüntülerine olan etkileri araştırılmıştır.Arterial spin labeling (ASL) based perfusion MRI has inherently very low signal-to-noise ratio (SNR). Therefore, these methods require rapid k-space coverage. This is often achieved by using a readout sequence such as gradient-echo-EPI. However, such a fast k-space traversal typically needs the gradients to be operated at the maximum of the hardware specks and to be alternated rapidly during the execution which makes acquisition highly sensitive to gradient field deviations. The resulting deviations in the gradient field time courses cause substantial artifacts on the reconstructed images. In this work, we directly recorded the gradient waveform fidelities using a dynamic field camera technology and reconstructed the acquired ASL data with monitored gradient waveforms. Furthermore, by assuming that the gradient chain is a linear time-invariant (LTI) system that enables to define the gradient impulse response function (GIRF) of the system as a one-time calibration procedure, the actual gradient waveforms can be predicted. We therefore additionally performed the reconstruction based on such GIRF-predicted k-trajectories. The ultimate effects of gradient field deviations on to the absolute perfusion maps were explored

Either Economize on Knowledge or Capitalize on Intellectuality: Educational Challenges for Economic Growth in the Turkish Republic of Northern Cyprus

Entelektüel sermaye, bilgi ekonomisinin en önemli unsurlarından birisidir. Bilgi yönetimiliteratüründe entelektüel sermaye ekonomik ve kültürel kalkınma açısından önemli faktörlerdenbiri olarak kabul edilmektedir. Bu nedenle, entelektüel sermaye birikimini oluşturan eğitim,ekonomik büyümenin vazgeçilmez bir değişkenidir. Kuzey Kıbrıs Türk Cumhuriyeti(KKTC)’nde eğitim, adada on üç üniversite olması sebebi ile ekonomik büyüme için önem teşkiletmekte, hükümetler tarafından öncü sektör olarak adlandırılmaktadır.Bu çalışma KKTC’nde bilgi ekonomisinin önemini vurgulayarak vatandaşların vedevletin bu konudaki farkındalığını artırmayı amaçlamaktadır. Söz konusu farkındalığınoluşabilmesi için, öncelikle bilgi ekonomisi değişkenlerinin ekonomik büyümeye olan etkisiölçülmüş, Engle-Granger nedensellik testi kullanılarak bilgi ekonomisi değişkenlerininbüyümeye neden olup olmadığı araştırılmıştır. Bu bağlamda okuryazarlık oranı, genel ve teknikliselere katılım oranı ve yükseköğretime katılım oranı bilgi ekonomisi değişkenleri olarakkullanılmıştır. Geliştirilmiş Cobb-Douglas üretim fonksiyonuyla geleneksel üretimfaktörlerinin yanı sıra, entelektüel sermayenin üretim sürecindeki etkisi 1977-2010 yılları içinölçülmüş ve üretimde artan verimin ekonomik büyümeye olan etkisi vurgulanmıştır. MakaledeKKTC ekonomisinin bilgi ekonomisi karakterini taşıyıp taşımadığı, kurulan model ve yapılantestler aracılığıyla denetlenmiş ve KKTC ekonomisinin bilgi ekonomisi olma yolundapotansiyeli olduğu sonucuna varılmıştır.well known in the knowledge management literature that knowledge has become an engine ofsocial, economic and cultural development in today’s world. Thus, education is a vital factorfor the accumulation of intellectual capital to reach economic growth. There are thirteenuniversities in the Turkish Republic of Northern Cyprus (TRNC), and higher education is amajor sector. Income generated from the education sector as well as the accelerating numberof universities are two important factors which TRNC government should pay attention to inregards to education and knowledge creation activities.The study aims to emphasize the importance of knowledge economy and to create bothpublic and government awareness particularly for TRNC and for other small economies aswell. The Engle-Granger Causality test in VAR model was used to analyse the causalrelationship between education and economic growth in TRNC and the results indicate apositive impact of knowledge economy variables on the economy’s productivity level. Literacyrate, general and technical high school enrolment rate and higher education enrolment rate is used as knowledge economy variables. Furthermore, the extended Cobb-Douglas production function is applied for the 1977-2010 period and emphasizes the increasing returns to scale in the production process within a given period in TRNC. Overall results show that the TRNC economy has a potential to become a knowledge economy

FT3/FT4 ratio predicts non-alcoholic fatty liver disease independent of metabolic parameters in patients with euthyroidism and hypothyroidism

OBJECTIVE: This study was performed to evaluate the effects of metabolic parameters and thyroid dysfunction on the development of non-alcoholic fatty liver disease (NAFLD). METHODS: The current study evaluated a total of 115 patients, 75 female and 40 male. Physical examination and anthropometric measurements were applied to all participants. Hypothyroidism was considered at a thyroid stimulating hormone level ≥ 4.1 mIU/L. Patients with euthyroidism and patients with hypothyroidism were compared. Abdominal ultrasonography was used to diagnose non-alcoholic fatty liver disease. The participants were further compared with regard to the presence of non-alcoholic fatty liver disease. Logistic regression modeling was performed to identify the relationship between non-alcoholic fatty liver disease and independent variables, such as metabolic parameters and insulin resistance. RESULTS: Non-alcoholic fatty liver disease was identified in 69 patients. The mean waist circumference, body mass index, fasting plasma insulin, HOMA-IR (

Snapshot evaluation of acute and chronic heart failure in real-life in Turkey: a follow-up data for mortality

Objective: Heart failure (HF) is a progressive clinical syndrome. SELFIE-TR is a registry illustrating the overall HF patient profile of Turkey. Herein, all-cause mortality (ACM) data during follow-up were provided. Methods: This is a prospective outcome analysis of SELFIE-TR. Patients were classified as acute HF (AHF) versus chronic HF (CHF) and HF with reduced ejection fraction (HFrEF), HF with mid-range ejection fraction, and HF with preserved ejection fraction and were followed up for ACM. Results: There were 1054 patients with a mean age of 63.3±13.3 years and with a median follow-up period of 16 (7–17) months. Survival data within 1 year were available in 1022 patients. Crude ACM was 19.9% for 1 year in the whole group. ACM within 1 year was 13.7% versus 32.6% in patients with CHF and AHF, respectively (p<0.001). Angiotensin-converting enzyme inhibitor/angiotensin receptor blocker, beta blocker, and mineralocorticoid receptor antagonist were present in 70.6%, 88.2%, and 50.7%, respectively. In the whole cohort, survival curves were graded according to guideline-directed medical therapy (GDMT) scores ?1 versus 2 versus 3 as 28% versus 20.2% versus 12.2%, respectively (p<0.001). Multivariate analysis of the whole cohort yielded age (p=0.009) and AHF (p=0.028) as independent predictors of mortality in 1 year. Conclusion: One-year mortality is high in Turkish patients with HF compared with contemporary cohorts with AHF and CHF. Of note, GDMT score is influential on 1-year mortality being the most striking one on chronic HFrEF. On the other hand, in the whole cohort, age and AHF were the only independent predictors of death in 1 yea

Conventional and Diffusion-Weighted MR Imaging Findings of Parotid Gland Tumors

Objective: To investigate diffusion-weighted magnetic resonance imaging (MRI) findings of parotid gland lesions in addition to conventional MRI findings and demographic data.Methods: A retrospective evaluation was made of the demographic data, histopathologic data, preoperative conventional and diffusion-weighted MRI of 74 patients who underwent parotidectomy. The patients were categorized according to the histopathology (pleomorphic adenoma [PA], Warthin’s Tumor [WT] and malignant Tumor [MT]).Results: Histologically, 30 patients had PA, 27 patients had WT, and the remaining 17 patients had MT. The mean age of the PA, WT and MT groups were 44±21 (20-72), 55±10 (41-71) and 62±20 (21-76) years, respectively. The WT (81%) and MT (70%) groups were male dominant, while the PA group showed female dominance (55%). The PA group showed statistically significant difference in terms of age (p<0.05) and gender (p=0.009) compared to the other two groups. The median apparent diffusion coefficient (ADC) values for the PA, WT and MT groups were 1.99±0.94 (1.10-2.41) x 10-3 mm2/s, 0.92±0.35 (0.21-1.79) x 10-3 mm2/s and 1.20±0.34 (0.78-1.47) x 10-3 mm2/s, respectively. PA was differentiated from the other two groups (p=0.001). The sensitivity and specificity for distinguishing PAs from WT was 97% and 85%, respectively, when the ADC cutoff value was 1.25; and for distinguishing PAs from MT was 77% and 83%, respectively, when the ADC cutoff value was 1.35.Conclusion: ADC measurements are useful for the differentiation of PA from both WT and MT; and can be used as a complementary tool to predict the histopathology in the preoperative planning of parotid tumors

The genetic history of the Southern Arc: a bridge between West Asia and Europe

By sequencing 727 ancient individuals from the Southern Arc (Anatolia and its neighbors in Southeastern Europe and West Asia) over 10,000 years, we contextualize its Chalcolithic period and Bronze Age (about 5000 to 1000 BCE), when extensive gene flow entangled it with the Eurasian steppe. Two streams of migration transmitted Caucasus and Anatolian/Levantine ancestry northward, and the Yamnaya pastoralists, formed on the steppe, then spread southward into the Balkans and across the Caucasus into Armenia, where they left numerous patrilineal descendants. Anatolia was transformed by intra–West Asian gene flow, with negligible impact of the later Yamnaya migrations. This contrasts with all other regions where Indo-European languages were spoken, suggesting that the homeland of the Indo-Anatolian language family was in West Asia, with only secondary dispersals of non-Anatolian Indo-Europeans from the steppe

Uyku bozuklukları araştırması için etkin ve hızlı bir horlama tespit yöntemi.

Snores are breath sounds that most people produce during sleep and they are reported to be a risk factor for various sleep disorders, such as obstructive sleep apnea syndrome (OSAS). Diagnosis of sleep disorders relies on the expertise of the clinician that inspects whole night polysomnography recordings. This inspection is time consuming and uncomfortable for the patient. There are surgical and therapeutic treatments. However, evaluation of the success of these methods also relies on subjective criteria and the expertise of the clinician. Thus, there is a strong need for a tool to analyze the snore sounds automatically, and to produce objective criteria and to assess the success of the applied treatment by comparing these criteria obtained before and after the treatment. In this thesis, we proposed a new algorithm to detect snoring episodes from the sleep sound recordings of the individuals, and created a user friendly interface to process snore recordings and to produce simple objective criteria to evaluate the results. The algorithm classifies sleep sound segments as snores and nonsnores according to their subband energy distributions. It was observed that inter- and intra-individual spectral energy distributions of snore sounds show significant similarities. This observation motivated the representation of the feature vectors in a lower dimensional space which was achieved using principal component analysis. Sleep sounds can be efficiently represented and classified as snore or nonsnore in a two dimensional space. The sound recordings were taken from patients that are suspected of OSAS pathology while they were connected to the polysomnography in Gülhane Military Medical Academy Sleep Studies Laboratory. The episodes taken from 30 subjects (18 simple snorers and 12 OSA patients) with different apnea/hypopnea indices were classified using the proposed algorithm. The system was tested by using the manual annotations of an ENT specialist as a reference. The system produced high detection rates both in simple snorers and OSA patients.M.S. - Master of Scienc

The life of Useyd b. Hudayr and his place in the history of Islam

Yüksek Lisans Tezi. YÖK Tez No:357839Hicretten sonra Medine'de İslâm'a hizmeti, Ensâr içerisinde İslâm'a girişteki önceliği, bunun yanı sıra Evs kabilesinin reisi oluşu, siyasi, askeri, sosyal, kültürel ve idarî hayattaki faaliyetleri, Rasûlüllah'a olan sevgisi, sahâbe arasındaki yeri ve hakkında yapılmış bir araştırma olmayışı bizi bu çalışmaya sevk etti. Bu yüzden araştırmaya " Üseyd b. Hudayr'ın Hayatı ve İslâm Tarihindeki Yeri" adı verildi. Meşhur künyesi Ebû Yahya olan Üseyd b. Hudayr, birinci Akabe Bey'ati'nden sonra Müslüman oldu ve ikinci Akabe Bey'ati'ne katılarak on iki Nakîb'den biri olarak seçildi. Hz. Peygamber ve Hulefâi Râşidin'den olan Ebû Bekir ve Ömer döneminde yaşadı. Hz. Peygamber döneminde askeri alandaki faaliyetlerin yanında idari, sosyal ve kültürel hayatta faaliyet gösterdi. Bu bağlamda sancaktarlık, müsteşarlık, imamlık, öğretmenlik ve kâtiplik görevlerinde bulundu. Ebû Bekir'in halife seçilmesinde etkin rol aldı. Ömer'in istihlâfında istişâre heyetinde bulundu. İdari, sosyal ve kültürel alandaki görevlerine Ebû Bekir ve Ömer döneminde de devam etti. Araştırma, bu çalışmanın konusu olan Üseyd b. Hudayr özelinde yürütüldü. Rivayetler nakledilirken gereksiz bilgi vermekten kaçınmakla beraber araştırmada insicamın sağlanması bakımından siyak ve sibak özet geçildi. Araştırmayla doğrudan ilgili olmayan fakat konu bütünlüğünü sağlayan bilgi, tanım ve anekdotlar, dipnotlarda verildi. Araştırmayla doğrudan ilgili olmayan ancak olaylar esnasında söylenegelen şiir ve sözlerin de adresleri dipnotlarda verildi. Araştırmamızı ilgilendiren, bunun yanında tercihen zayıf olduğu düşünülen ya da öyle olduğu bizzat kaynak eserin müellifi tarafından bildirilen rivayetler de dipnotlarda verildi.His serving for Islam in Madina after Hegira, his initially accepting Islam within Ansar, being the leader of the Evs tribe besides this, his activities in the political, military, social, cultural and administrative lives, his sympathy to the Prophet, his place among the sahabe (companion) and having no research made about him has brought us into this study. Therefore, the study is named as "The Life of Useyd b. Hudayr and His Place in the History of Islam". Useyd b. Hudayr, whose famed identity is Ebû Yahya, became Muslim after the first Akabe homage and selected to be one of the twelve deputies joining in the second Akabe homage. He lived in the period of Ebu Bekir and Omar who were from the Prophet and Hulefâi Râşidin. Besides his activities in the military arena during the Prophet's period, he was active in administrative, social and cultural lives. In this context, he held office in being flag-bearer, undersecretariat, imamate, teaching and clerkship jobs. He played an effective role in the election of Ebu Bekir to be the Caliph. He participated in the consultation meetings during the recommendation of Omar. He carried on his servicing in the administration, social and cultural filed during the period of Omar and Ebu Bekir. The research has been executed in the privacy of Useyd b. Hudayr, who is the topic of this study. Although avoiding to give trivial information while narrating the rumors, the previous andpost summaries are given in terms of ensuring coherence in the study. The information, description and anecdotes which are not directly related to the study, but ensure integrity with the topic are given in the footnotes. The addresses of poems and sayings which are not directly related to the study, but uttered during the instances are also given in the footnotes. The narrations which concern our study and beside this, preferably considered to be bare or informed by the author of the resource work in person are also given in the footnotes