In memory of Res. Assist. Mustafa Fidan

Mustafa Fidan, 25 Mart 1978’de İstanbul’da doğdu. 1992-1996 yılları arasında İstanbul Maçka Akif Tuncel Teknik Lisesi Elektronik Bölümü’nde okudu. 1996 yılında Ankara’da Hacettepe Üniversitesi Fizik Mühendisliği bölümünde okumaya başlayan Mustafa Fidan, 2001 yılında derece ile mezun oldu. Boğaziçi Üniversitesi, Biyomedikal Elektronik Mühendisliği bölümünde yüksek lisans programına kabul edildi. Yüksek Lisans çalışmalarını sürdürürken, 1 Ekim 2002 tarihinde Doğuş Üniversitesi Fen Edebiyat Fakültesi, Fen Bilimleri Bölümü’nde Fizik Birimi Araştırma Görevlisi olarak çalışmaya başladı. 2005–2006 yılları arasında askerlik görevini yaptı ve Doğuş Üniversitesi’ndeki görevine kaldığı yerden devam ettti. 7 Eylül 2007 tarihinde Gülşah Kaçur ile evlendi. Mustafa, kendisini kaybettiğimiz elim kazanın olmasından önce, yüksek lisans programını bitirdiği Boğaziçi Üniversitesi Biyomedikal Elektronik Mühendisliği Bölümü’nde 2006 yılında başladığı doktora programına devam etmekteydi. ..

Spin polarized tunneling in large area mesas of superconducting Bi2Sr2CaCu2O8+d for terahertz emission

Thesis (Master)--Izmir Institute of Technology, Physics, Izmir, 2010Includes bibliographical references (leaves: 70-77)Text in English; Abstract: Turkish and Englishxi, 77 leavesThere is an increasing interest in science and technology of electromagnetic waves in terahertz frequency range (0.1-10 THz) because of their emerging application areas including physics, biology, chemistry, astronomy, medicine etc. The observation on generation of THz radiation emitted from lateral dimension of high temperature superconductor (HTS) Bi2Sr2CaCu2O8+.. (Bi2212) and responses to THz waves increase the importance of these HTSs. Single crystal of HTS Bi2212 forms natural superconductor-insulator-superconductor (SIS) layered junctions, which are called intrinsic Josephson junctions (IJJ). The stacks of IJJs in Bi2212 can be used such a voltage-frequency converter and their large energy gap allows the emissions at THz frequency range. Recently, it has been demonstrated that rectangular IJJ mesa structures of Bi2212 can be used as a source of continuous, coherent and polarized THz radiation. It was shown that all THz emitting mesas are below a certain underdoped level, which has relatively small critical current in contrast to optimally doped and overdoped Bi2212. In this work, rectangular Au/Co/Au/Bi2212 mesa structures with large areas and high thicknesses were fabricated on as-grown Bi2212 single crystals using standard photolithograph and Ar ion beam etching techniques. In order to characterize the mesas, c-axis resistance versus temperature (R-T) and current-voltage (I-V) characteristics were investigated. During I-V characterization, Si composite bolometer was used to detect the emission. We obtained small critical current from as-grown mesas due to injection of spin polarized current. We observed THz emission peak for one of the mesas which has low quasiparticle conductivity and low dissipation due to its small critical current density. It means that the adjustment of doping level can be eliminated for THz emission by the injection of spin polarized current through the c-axes of the asgrown mesas

Metaphoric images of the strategic management concept: Research on upper- and middle-level managers

Purpose: The purpose of this study is to explain how organizational actors create their own reality with their subjective perceptions and interpretations of organizational phenomena. In this context, strategic management, which is fed from many different disciplines, is examined in terms of what it means for its practitioners. In other words, it is questioned how the concept of strategic management is defined in the eyes of organizational actors. Method: A qualitative research method was used to achieve the purpose determined in the study, as well as metaphor analysis, which is one of the qualitative research designs evaluated within the scope of discourse analysis. The data obtained from a total of 40 participants were subjected to content analysis and descriptive analysis. Result: As a result of the obtained data set analysis, it was determined that the participants produced impressive metaphors while defining the concept of strategic management. In addition, it was noted that the participants defined the concept of strategic management with sometimes similar and sometimes almost the same metaphors. Conclusion: According to the analysis results, the dominant images among the managers match the definition of the concept of strategic management. In addition, it has been concluded that the shared reality among organizational actors is regular, clear and understandable, and that the dominant images in the shared reality are strong. Furthermore, 1) this article reveals how the concept of strategic management defined by academics is perceived by practitioners, 2) it was observed that the participants exhibited consensus rather than conflict in their evaluations of the concept of strategic management, and 3) the different metaphors used are considered as proof that the strategic management field has a lively, active and broad intellectual content

Delta Hepatitis

Hepatitis delta virus (HDV) is a defective RNA virus that requires HBsAg for replication and transmission. It can cause acute or chronic hepatitis. Chronic infection with HDV is one of the most severe and difficult to treat forms of viral hepatitis. It has been estimated that there is a total of 15-20 million HDV carriers in the world. This review focuses on two fundamental aspects of HDV infection. On the one hand, epidemiological data are summarized, which are essential to understand the real burden of this disease. After the HBV vaccination programs in many countries all over the world, HDV infection has decreased since 1980’s but this decline has not continued further in the last decade. Therefore, HDV infection is still an important public health problem in the world. On the other hand, therapeutic options are described. Currently, interferons are the only option for the treatment of chronic hepatitis delta infection, and pegylated-interferons have shown better results than conventional interferons (IFNs). Monotherapy of nucleos(t)ide analogs have been found ineffective against the HDV infection, but adefovir and pegylated-IFN combination therapy have had some advantages for reduction of HBsAg levels. Trials with more potent nucleoside analogs and pegylated-IFN could be effective in the treatment of chronic HDV infection. New agents like prenylation inhibitors, that can affect the interactions between the large HDV antigen and HBsAg in the HDV virion, will be a hope in treatment of HDV infection

Examination of deterioration problems of andesite used in Aigai Agora

Thesis (Master)--Izmir Institute Of Technology, Architectural Restoration, Izmir, 2009Includes bibliographical references (leaves: 73-75)Text in English; Abstract: Turkish and Englishxii, 75 leavesThe archaeological sites should be conserved as being the documents of ancient civilizations as a part of the built cultural heritage. In this study, the deterioration problems of stone used in the construction of the agora building in the archaeological site of Aigai (Manisa/Turkey) was investigated for the aim of its conservation. For this purpose, the building was documented by photographs and drawings. The stone deteriorations were documented on the drawings and samples were collected from the deteriorated and sound parts of stones. Basic physical properties, mineralogical, chemical and microstructural characteristics of the stone samples were determined to define the causes of deteriorations. X-Ray diffraction, scanning electron microscope, polarized microscope, infrared spectroscopy and thermogravimetric analyzer were used in the analysis. The stone used in the building is andesite which is mainly composed of andesine, albite high, anorthite, kyanite, labradorite, muscovite, microline, mullite, orthoclase, orthoferrosilite, quartz, sanidine and tridymite minerals. The density and porosity values of sound andesite are 2.4 g/cm3 and 8 % by volume respectively. On the weathered parts of the stone, the porosity increases with degree of weathering. The depth of the weathered zone from the surface to the inner parts which was determined by SEM analysis is about 1.7 cm. On the weathered parts of stone, clay minerals and iron oxides were determined as weathering products of andesite. The existence of clays on the exterior and the interior parts of the andesite accelerates weathering by their swelling.shrinkage properties and provide suitable conditions for the biological growth. Main weathering forms observed on the stone surfaces are detachment, deposits and loss of stone materials. The progress of weathering forms depends mainly on the difference in temperature and humidity between night and day at the site. Condensation and frost occurs mostly in winter months with increasing relative humidity and decreasing temperature. Humid and rainy conditions of winter months promote the weathering of the stone