Nonobstruktif azospermi olgularında yeni yaklaşımlar

Azospermi semende hiç sperm bulunamaması durumudur. Obstrüktif ve nonobstrüktif olmak üzere iki kategoriye ayrılır. Azospermi tanısı alan hastalardan elde edilen spermatozoayla, ilk gebelik ICSI (intrasitoplazmik sperm enjeksiyonu) işlemiyle 1993 yılında oluşmuştur. Obstrüktif azospermi olgularında sperm bulma şansı daha yüksek olmasına karşın, erkek infertilitesinin en şiddetli formu olan nonobstrüktif azospermide ise bu oran yaklaşık olarak %40-50 aralığındadır. Yapılan mikroTESE (testiküler sperm ekstraksiyonu) işlemiyle testiste immatür germ hücreleri bulunursa ROSI (round spermatid enjeksiyonu) işlemi yapılır ya da in vitro kültürlerle bu hücreler farklılaştırılmaya çalışılır. Matür germ hücresi bulunamayan bir mikroTESE sonrasında, hormon replasmanı veya ilaç tedavileriyle spermatozoaların elde edilmesi hedeflenir. Son yıllara kadar testislerde varlıkları bilinen spermatogoniumlara (sperm kök hücresi) ek olarak, yeni keşfedilen VSEL (very small embriyonic-like stem cell) kök hücrelerinin gösterilmesi tedavi yönündeki umutları daha da artırmıştır. Bunlardan başka deneysel olarak, hücre kültürleri, seminifer tübül kültürleri, organ kültürleri, testiküler organoidler, gen tedavileriİnsan üzerinde başlayan gen terapilerinde ve mezenkimal kök hücre çalışmalarında, önemli ilerlemeler olması nedeniyle yakın bir zamanda azospermi tedavisinde de önemli gelişmeler olacağı düşünülmektedir. ve kök hücre bazlı tedavilerin etkinliği gösterilmiştir

Status-seeking and catching up in the strategic Ramsey model

Ankara : The Department of Economics, Bilkent University, 2008.Thesis (Master's) -- Bilkent University, 2008.Includes bibliographical references leaves 30-31.This thesis analyzes the qualitative implications of the strategic interaction on the standard Ramsey model in terms of catching up. We have shown that the strategic interaction among agents in the economy leads the poor to be able to catch up with the rich, which is not the case for the standard Ramsey model where the initial wealth differences perpetuate. Secondly, within this framework, we incorporate the relative wealth effect and conclude that the catching up amoung agents depends on the share of two classes in the economy. If the share of two classes is same, there exist unique symetric steady state, whereas if the share of two classes are different the steady state is assymetric. Morever, the steady state level of aggregate capital stock is higher than the that of standard Ramsey model. Finally, we introduce the relative consumption effect and reach the conclusion that whatever the share of classes, the gap between the initial wealth level of two classes will disappear in the long run. In addition, the steady state level of aggregate wealth level is same with the that of standard Ramsey model.Özer, MehmetM.S

Geçici Koruma Altındaki Suriyeli Öğrencilerin İlk Okuma Yazma Öğretiminde Karşılaşılan Sorunlara İlişkin Öğretmen Görüşleri

Çalışmanın amacı geçici koruma altındaki Suriyeli öğrencilerin ilk okuma yazma öğretiminde karşılaşılan sorunlara ilişkin öğretmen görüşlerini inceleyip buna dair çözüm önerileri sunmaktır. Çalışmada nitel araştırma desenlerinden biri olan durum çalışması deseni kullanılmıştır. Çalışma grubunu 2021-2022 eğitim-öğretim yılında Şanlıurfa Haliliye ilçesinde Suriyeli öğrencilerin en yoğun olan ilkokullarında görev yapmakta olan 30 sınıf öğretmeni oluşturmuştur. Veriler on tane açık uçlu sorudan oluşan yarı yapılandırılmış bir görüşme form aracılığıyla elde edilmiş ve bu veriler betimsel analiz tekniği olan içerik analizi ile elde edilmiştir. Araştırmanın bulgularına göre Geçici Koruma Altındaki Suriyeli öğrencilerin ilk okuma yazma öğretiminde karşılaşılan sorunlarına yönelik olarak en çok dil problemi yaşadıklarını bunu uyum, şiddet ve disiplin problemlerinin izlediği; öğretim boyutunda ise daha çok okuma-telaffuz, dil farklılığına bağlı problemlerin olduğu, öğretmenlerin bunlara çözüm olarak en çok görsel, video ve somut materyallerle destekleyip akran öğretimini kullanarak öğrencilerle bireysel ilgilendiklerini söylemişlerdir. Sorunların çözümü için en çok çeviri programlarını kullandıklarını, öğrencilere yönelik hazırlık eğitimi, dil kursu ve ana sınıf eğitimini çok önemli buldukları sonuçlarına ulaşılmıştır. Velilere yönelik olarak ise dil eğitimi ve okuma yazma öğretiminin verilmesiyle birlikte süreç boyunca rehber öğretmenler tarafından gerekli eğitimlerinin verilerek okula uyumlarının artırılması için veli ziyaretlerinin yapılabileceği sonuçlarına ulaşılmıştır

Experimental setup design for liquid sloshing

Sloshing problems are highly non-linear problems and obtaining an accurate solution with numerical simulations is difficult and requires long simulation times. For this reason, sloshing experiments are important to understand the sloshing characteristics of liquid and to validate the theoretical and numerical studies in this field. In this study, an experimental setup which can input sine or random inputs to a sloshing system is designed and verified for different input amplitudes and frequencies. Then, the effect of vibration frequency and amplitude on the amplitudes of wave height and sloshing force are investigated. The effect of base motion frequency and the sloshing natural frequency on sloshing characteristics is also investigated

A Novel Artificial Pancreas: Energy Efficient Valveless Piezoelectric Actuated Closed-Loop Insulin Pump for T1DM

The objective of this work is to develop a closed-loop controlled insulin pump to keep the blood glucose level of Type 1 diabetes mellitus (T1DM) patients in the desired range. In contrast to the existing artificial pancreas systems with syringe pumps, an energy-efficient, valveless piezoelectric pump is designed and simulated with different types of controllers and glucose-insulin models. COMSOL Multiphysics is used for piezoelectric-fluid-structural coupled 3D finite element simulations of the pump. Then, a reduced-order model (ROM) is simulated in MATLAB/Simulink together with optimal and proportional-integral-derivative (PID) controllers and glucose-insulin models of Ackerman, Bergman, and Sorensen. Divergence angle, nozzle/diffuser diameters, lengths, chamber height, excitation voltage, and frequency are optimized with dimensional constraints to achieve a high net flow rate and low power consumption. A prototype is manufactured and experimented with different excitation frequencies. It is shown that the proposed system successfully controls the delivered insulin for all three glucose-insulin models

Sex Determination Using the Scapula in Medieval Skeletons from East Anatolia

Sex determination from skeletal human remains by discriminant function analysis is one of the methods utilized in the forensic and osteoarcheological sciences. The purpose of the present study is to establish metric standards for sex determination for medieval Anatolian populations using scapular measurements. The database for this research consisted of 93 adult skeletal remains (47 males and 46 females) from the Dilkaya medieval collection. Four measurements were taken: maximum scapular height, maximum scapular breadth, glenoid cavity height, glenoid cavity breadth, and subjected to discriminant function analysis. All measurements demonstrated some degree of sexual dimorphism, with the highest accuracy of sex determination (94.8%) obtained using maximum scapular breadth. Overall accuracies of the functions ranged from 82.9% to 95.0%, with a higher accuracy rate obtained for female skeletons than for males. Population specific discriminant formulas were developed using combinations of measurements, which can be used in ancient Anatolian populations

Characterization of viscoelastic materials using free-layered and sandwiched samples: assessment and recommendations

Viscoelastic materials are widely used in many applications in practice. However, determination of the elastic and damping properties of these materials is quite difficult in the sense that the identified results may contain high degree of uncertainty. The characterization of viscoelastic materials using the Oberst beam method, based on non-contact excitation and response measurements, is revisited in this paper. The effects of signal processing parameters such as frequency resolution in Frequency Response Function (FRF) measurements, as well as the effects of various single-degree-of-freedom modal analysis methods, including circle-fit, half-power and line-fit are investigated first. Then, the modal loss factors, Young's modulus and shear modulus of some sample viscoelastic materials are identified using both the free-layered and sandwiched samples. The results obtained from different tests are compared, discussed and some recommendations are made so as to identify the damping and elastic properties of typical viscoelastic materials with better accuracy. Analyses of a large number of FRF measurements show that the selection of the appropriate signal processing parameters and the use of appropriate modal analysis method can be very significant during the identification of viscoelastic materials. By following the approach presented in this paper, the damping and elastic properties of viscoelastic materials can be identified with better accuracy using either free-layered or sandwiched samples. The material properties obtained by this approach can be used for developing valid structural models and/or for damping optimization purposes.WOS:000357937100110Scopus - Affiliation ID: 60105072Science Citation Index Expanded - Conference Proceedings Citation Index- ScienceQ4Article; Proceedings PaperUluslararası işbirliği ile yapılmayan - HAYIRNisan2015YÖK - 2014-1

Halbjahresergebnisse einer neuen faltbaren Hinterkammerlinse aus Acryl, AcrySof® MA60BM

Das Forschungsziel dieser Arbeit war die Abklärung der Frage, ob sich in implantierten Intraokularlinsen der Marke Acrysof®, die in Deutschland kurz nach deren Markteinführung erworben wurden, Mikrovakuolen im Optikkörper befinden. Diese sogenannten Glistenings, die der Hersteller auf eine neuartige Verpackung zurückführte, welche ausschließlich in den Vereinigten Staaten Verwendung fand, führten in den USA zu Explantationen und zum Rückruf so verpackter Kunstlinsen dieses Typs. Unser Arbeitsprogramm umfaßte hauptsächlich die Untersuchung von Patienten, bei denen eine Acrysof®-Intraokularlinse implantiert wurde, an der Spaltlampe und anschließende Dokumentation mittels Fotospaltlampe. Zusätzlich wurden Sehschärfebestimmungen durchgeführt. Analog wurden Untersuchungen und Dokumentationen bei Patienten, denen im gleichen Zeitraum und vom gleichen Operateur eine herkömmliche PMMA-Kunstlinse implantiert wurde, durchgeführt. In allen untersuchten Intraokularlinsen des neuen Modells aus Acryl konnten Mikrovakuolen festgestellt und fotografisch dokumentiert werden. Diese Veränderungen konnten in keiner der PMMA-Kunstlinsen beobachtet werden. In unseren Ergebnissen fanden sich sonst durchgehend Hinweise auf die mittlerweile von anderen gewonnenen Erkenntnisse über die neue Linse. Es konnten keine Hinweise auf eine Visusminderung durch die Glistenings festgestellt werden. Die Analyse der Literatur ergab, daß nach dem heutigem Stand der Erkenntnisse über die Glistenings, von einer Flüssigkeitsaufnahme in den Optikkörper der IOL ausgegangen wird. Die Flüssigkeit sammelt sich in einige mikrometer großen Räumen in der Polymerstruktur der Kunstlinse. Diese Mikrovakuolen werden durch die Brechkraftdifferenz zwischen deren Inhalt und dem IOL-Material optisch sichtbar und erscheinen bei der Spaltlampenuntersuchung als multiple Glitzerpunkte. Experimentelle Arbeiten haben gezeigt, daß die Ausbildung der Mikrovakuolen durch Temperaturschwankungen und durch die Anwesenheit von Serum begünstigt wird. Ein verstärktes Vorkommen der Glistenings bei Patienten, bei denen sich durch Beeinträchtigung der Blut-Kammerwasser-Schranke oder der Blut-Retina-Schranke, Serumbestandteile im Kammerwasser befinden können, hier sind besonders Diabetiker zu nennen, wurde von einigen Autoren berichtet. Auch wir konnten bei einer nachträglichen Auswertung unserer Unterlagen Hinweise darauf finden, daß es bei solchen Patienten zur verstärkten Glisteningbildung kommt. Die Aussage der Herstellerfirma, die Glistenings hingen mit der neuartigen Verpackung und Sterilisation der IOLs in dem AcryPak-System, welches nur in den USA zum Einsatz kam und 1995 vom Markt genommen wurde, zusammen, wurde durch unsere Ergebnisse widerlegt. Besonders die frühere englischsprachige Literatur spiegelt einen Konsens mit der vom Hersteller vertretenen Auffassung wider. Neuere Arbeiten, die unsere Ergebnisse bestätigen weisen auf ein Poster auf einem Kongress 1999 in Seattle als erstes bekanntwerden von Glistenings in herkömmlich verpackten AcrySof®-IOL hin, obwohl schon frühere Berichte von Autoren aus Europa, auch von unserer Arbeitsgruppe, vorlagen. Die Mikrovakuolen haben nur in sehr seltenen Einzelfällen, bei denen es zu massenhaftem Vorkommen gekommen war, zu Beeinträchtigungen der Sehfunktionen geführt und eine Explantation erforderlich gemacht. Trotzdem sind weitere Forschungen, für die wir einige Ansätze vorschlagen, notwendig. Auch das Vorkommen von schwerwiegenden Trübungen bei anderen Kunstlinsentypen zeigt die Notwendigkeit für verstärkte Forschungen und gesetzliche Regulierungen auf diesem Gebiet. Insbesondere die hervorragend niedrigen Nachstarraten, die mit der Implantation von AcrySof®-Kunstlinsen einher gehen, berechtigen jedoch zu ihrer Weiterverwendung. Während es unwahrscheinlich scheint, daß die Glistenings noch schwerwiegende Probleme bereiten werden, so ist jedoch gesichert, daß durch die Verwendung von AcrySof®Kunstlinsen weniger YAG-Laser-Kapsulotomien notwendig sind. Daß sich damit auch die mit diesem Eingriff verbundenen Kosten und Komplikationen reduzieren ist selbstredend. Der Verlauf der Forschungen zu diesem Thema wird dargelegt. Die Notwendigkeit präziserer Studienaufbauten und besserer technischer Ausstattung wird deutlich. Durch den fortgeführten Einsatz der AcrySof®-IOL wurde die ophthalmologische Sichtweise der IOL verändert. Die IOL wird heute als Implantat betrachtet, welches die Aphakie korrigiert aber auch den Nachstar verhüten soll. Im kleinen Rahmen der Entwicklungsgeschichte der IOLs selbst, könnte dies den Beginn einer neuen IOL-Generation bedeuten.This study has been conducted to clarify the presence of microvacuoles within the optics of implanted AcrySof®-brand intraocular lenses (IOLs). These lenses were implanted in the Federal Republic of Germany, shortly after they became commercially available in December 1994. According to the manufacturing company, microvacuoles, also called glistenings, were caused by a new type of packaging which was used in the USA only. This situation led to explantations of IOLs and to the recall of lenses packed in that new manner. The main thrust of our fesearch program was the slitlamp examination of patients who had an implanted AcrySof®-lens. The findings were documented by means of slitlamp-photography. In addition, visual acuity tests were conducted. At the Same time, analog examinations and documentations of a second group of patients were done. These patients had been operated by the Same surgeon ,during the Same months as the patients of the AcrySof®-Group, but had common poly(methy1 methacry1ate)-I0Ls in their eyes. In all acrylic intraocular lenses microvacuoles could be found and documented. This phenomenon could not be Seen in any of the examined poly (methyl methacrylate)-IOLs. Our research also identified newer findings published by other investigators concerning the Acrysof®-IOL, We did not detect any signs of visual acuity reduction caused by the glistenings. Our literature search reveals that the glistenings have to be looked at as fluid uptake from the aqueus to the optic-body of the IOL. The fluid gathers in spaces within the polymer-structure of the IOL. The glistenings have a dimension of a few micrometers. Due to the different refractive indices of the content of the vacuoles and the IOL-material, the microvacuoles become visible as multiple pinpoint glistenings. Experimental work has shown that the formation of the glistenings increases with fluctuating temperature and the presence of serum. Some investigators have reported an increased prevalence of glistenings in patients who may have serum-components in the aqueus, caused by a compromised blood-aqueus-barrier or a compromised blood-retina-barrier, e. g. persons with diabetes. In this regard a reevaluation of our data showed signs of increased glistening-formation in above mentioned patients. The statement of the manufacturing company, that glistenings coincide with the packaging- and sterilisation of the IOLs with the new AcryPak-system, could be disproved by our results. The early literature in English shows a Consensus with the manufacturer's assertion. However, recent studies, referring to a poster presentation at the 1999 ASCRS meeting in Seattle, as the first publication of glistenings in commonly packed AcrySof®-IOLs, confirm our results. Earlier reports had been published by european authors, including our study-group. Although glistenings have resulted in very few explantations due to reduced visual accuity further research on this topic is necessary. Furthermore, the existence of severe opacities in other types of IOLs, suggests the necessity of increased research and legal regulation concerning this topic. The very low rates of posterior capsule opacification (PCO) following AcrySof®-IOLimplantations justify their use. While it is not likely that the glistenings will cause any severe problems, it is evident that implantation of AcrySof®-IOLs results in lower laser-capsulotomy-rates with a decreasing number of capsulotomy-associated complications and healthcare-cost-reduction. The Course of scientific research on the PCO-preventive effect of the AcrySof®-IOL is described in our discussion. We conclude that studies should be planned more precisely and should be conducted with equipment of higher technical standards. The continuous use of AcrySof®-IOLs changed the ophthalmologists' understanding of IOLs as such. Today the IOL is looked upon as an implant that corrects aphakia, but should also prevent PCO. From the perspective of the history of IOLs, this could mark the beginning of a new generation of IOL