ABSTRACT CONSERVED CHARGES IN ASYMPTOTICALLY (ANTI)-DE SITTER SPACETIME G&Uuml / LL&Uuml / , iBRAHiM M.S., Department of Physics Supervisor: Assoc. Prof. Dr. Bayram Tekin August 2005, 77 pages. In this master&rsquo / s thesis, the Killing vectors are introduced and the Killing equation is derived. Also, some information is given about the cosmological constant. Then, the Abbott-Deser (AD) energy is reformulated by linearizing the Einstein equation with cosmological constant. From the linearized Einstein equation, Killing charges are derived by using the properties of Killing vectors. Using this formulation, energy is calculated for some specific cases by using the Schwarzschild-de Sitter metric. Last, the Einstein-Gauss-Bonnet model is studied. The equations of motion are calculated by solving the generic action at quadratic order. Following this, all energy calculations are renewed for this model. Some useful relations and calculations are shown in Appendix (A-B) parts. &Ouml / Z ASiMPTOTiK (ANTi)-DE SITTER UZAYZAMANINDA KORUNAN Y&Uuml / KLER G&Uuml / LL&Uuml / , iBRAHiM Y&uuml / ksek Lisans, Fizik B&ouml / l&uuml / m&uuml / Tez Y&ouml / neticisi: Assoc. Prof. Dr. Bayram Tekin Agustos 2005, 77 sayfa. Bu master &ccedil / aliSmasinda, Killing vekt&ouml / rler tanimlandi ve Killing denklemi &ccedil / ikarildi. Ayrica evrenbilimsel sabit, de-Sitter ve Anti-de Sitter uzaylari hakkinda bilgi verildi. Sonra, Abbott-Deser (AD) enerjisi, evrenbilimsel sabitli Einstein denklemi dogrusallaStirilarak yeniden form&uuml / le edildi. DogrusallaStirilmiS Einstein denkleminden, Killing vekt&ouml / rlerin &ouml / zellikleri kullanilarak Killing y&uuml / kleri (Deser-Tekin denklemi) &ccedil / ikarildi. Schwarzschild-de Sitter metrigi kullanilarak &ouml / zel durumlar i&ccedil / in enerji hesaplandi. Son olarak Einstein-Gauss-Bonnet (GB) modeli &ccedil / aliSildi. ikinci dereceden genel eylem &ccedil / &ouml / z&uuml / lerek hareket denklemleri hesaplandi. Bundan sonra, t&uuml / m enerji hesaplamalari bu model i&ccedil / in tekrarlandi. Bazi faydali hesaplamalar ek (A-B) kisimlarinda g&ouml / sterilmiStir.

SYNTHESIS OF FERROCENYL CYCLOHEPTADIENONES A&ccedil / ikg&ouml / z, Canet M.S., Department of Chemistry Supervisor: Assoc. Prof. Dr. Metin Zora August 2005, 85 pages Synthesis of seven-membered ring systems such as cycloheptadienones has attracted a great deal of attention in organic chemistry since they are present in a variety of biologically important molecules. Incorporation of the essential structures of such compounds with a ferrocene moiety instead of an aryl group could provide subtances with enhanced antitumor activities since some ferrocene derivatives have already proved to be active against a number of tumors. To develop a ferrocenyl-substituted seven-membered ring forming reaction, we have investigated the reaction of cyclopropylcarbene-molybdenum complex with ferrocenyl-substituted alkynes. As ferrocenyl-substituted alkyne, ferrocenyl&not / propyne (25B), (2-ferrocenylethynyl)trimethylsilane (25C), 1-ferrocenyl-3-phenylprop-1-yne (25D), 1-ferrocenyl-2-phenylethyne (25E), diferrocenylethyne (25F), ferrocenyl(formyl)acetylene (25G) were synthesized starting from ethynylferrocene (25A). The reaction between cyclopropylcarbene-molybdenum complex and ferrocenyl alkynes produced ferrocenyl-substituted cycloheptadienones 26, hydrolysis product of cycloheptadienones, 27, &amp / #61537 / -hydroxycycloheptadienones 28 and cyclobutenones 29, depending on the substitution pattern of the alkyne moiety. Interestingly, &amp / #61537 / -hydroxycycloheptadienone product 28B was isolated from these types of reactions for the first time. Terminal alkynes, trimethyl- and formyl-substituted alkynes did not produce any expected product, possibly depending on the steric and electronic effects, and/or the polymerization of the alkyne. Proposed mechanism for the formation of cycloheptadienones involves metallacyclobutene formation, electrocyclic ring opening, electrocyclic ring closure, CO insertion, reductive elimination.

Urban public spaces have always been subjected to physical, economical,social, political and cultural transformations of the city. These changing dynamics could cause decay in the spatial qualities and could also lead to a loss of values and identities of urban spaces, especially in public spaces. This thesis explores the qualities of a particular urban space in Istanbul: the Emin&ouml / n&uuml / Square. Providing a guideline for the future urban design projects,the structure and the identity of the historical public space is aimed in this thesis. Firstly, in order to evaluate the qualities of urban public space a method of analysis has been developed in the study. For this purpose, the urban design theories and their methodologies of analysis have been discussed with respect to three main headings: urban form, urban activity and urban image. Furthermore, as parallel to this purpose, the criteria of the quality of urban space are developed by the help of the morphological, visual and perceptual analyses. In the second stage, the formation-transformation processes of the Emin&ouml / n&uuml / Square, spatial dynamics and urban operations have been discussed within the framework of the method of analysis in a historical aspect. The results of the analyses show that the spatial dynamics and the urban operations affected the quality of the Square negatively in all formal, visual,social and perceptual aspects. In other words, the Emin&ouml / n&uuml / Square lost its well-defined formal structure and transformed to a space which is deprived of activity structure and legible identity.

Early Warning Systems (EWSs) for banking sectors are used to measure occurrence risks of banking crises, generally observed with a rundown of bank deposits and widespread failures of financial institutions. In countries with a small number of banks, for example Turkey with 48 banks (BDDK, 2011), every bank may be considered to have a systematic importance since the failure of any individual bank may carry a potential threat to lead to a banking crisis. Taking into account this fact the present study focuses on EWSs in Turkey. Since there is no single correct EWS to apply to all cases, in this study, 300 models were constructed and tested to find models as accurate as possible by using a trial-and-error process and by searching optimal feature subset or classifier methods. Empirical results indicate that prediction accuracy did not increase significantly while we got closer to the actual occurrence of bankruptcy. An important finding of the study was that trends of financial ratios were very useful in the prediction of bank failures. Instead of failures as a result of instant shocks, the banks&#039 / failures followed through a path: first a downward movement affected the efficiency of the banks&#039 / officers and the quality of management structure measured with &quot / Activity Ratios&quot / , then the profitability of the banks measured with &quot / Profit Ratios&quot / declined. At last, the performance and the stability of banks&#039 / earnings stream measured with &quot / Income-Expenditure Structure Ratios&quot / and the level and quality of the banks&#039 / capital base, the end line of defense, measured with &quot / Capital Ratios&quot / . At the end of study, we proposed an ensemble model which produced probability ratios for the success rates of the banks. The proposed model achieved a very high success rate for the banks we considered.

In recent years nickel is mostly produced from lateritic ore deposits such as nontronite, limonite, etc. Resource estimation is difficult for laterite deposits as they have a weak and heterogeneous form. 3D modeling software are rather suitable for deposits having tabular or vein type ores. In this study the most appropriate estimation technique for resource estimation of nickel laterite deposits was investigated. One of the known nickel laterite deposits in Turkey is located at T&uuml / rkmen&ccedil / ardagi - G&ouml / rdes region. Since the nickel (Ni) grade recovered from drilling studies seem to be very low, a reconciliation pit having dimensions of 40 m x 40 m x 15 m in x-y-z directions was planned by Meta Nikel Kobalt Mining Company (META), the license owner of the mine, to produce nickel ore. 13 core drilling and 13 reverse circulation drilling (RC) and 26 column samplings adjacent to each drillholes were located in this area. Those three sampling results were compared to each other and as well as the actual production values obtained from reconciliation pit. On the other side 3D computer modeling was also used to model the nickel resource in T&uuml / rkmen&ccedil / ardagi - G&ouml / rdes laterites. The results obtained from both inverse distance weighting and kriging methods were compared to the results of actual production to find out the applicability of 3D modeling to laterite deposits. Modeling results showed that Ni grade of the reconciliation pit in T&uuml / rkmen&ccedil / ardagi - G&ouml / rdes, considering 0.5% Ni cut-off value, by using drillholes data, inverse distance weighting method estimates 622 tonnes with 0.553% Ni and kriging method estimates 749 tonnes with 0.527% Ni. The actual production pit results provided 4,882 tonnes of nickel ore with 0.649% Ni grade. These results show that grade values seem to be acceptable but in terms of tonnage, there are significant differences between theoretical estimated values and production values.

This thesis attempts to give the increasing importance of Ottoman port cities in the urban hierarchy during the nineteenth century and analyzes the urban transformation of these cities under the forces of changing administrative and socio-economic structure of the empire. The impact of European economic penetration and Ottoman Tanzimat Reforms were indicated as major causes for this changing structure. Beirut, being one of the major port cities of the Ottoman Empire is studied as a case study. The changing administrative and socio-economic structure of the Empire created an urban transformation which changed the city to a cosmopolitan trade capital from a small fortified port city.

The one dimensional position dependent effective mass problem is studied by solving the Schr&ouml / dinger equation for some well known potentials, such as the deformed Hulthen, the Mie, the Kratzer, the pseudoharmonic, and the Morse potentials. Nikiforov-Uvarov method is used in the calculations to get energy eigenvalues and the corresponding wave functions exactly. By introducing a free parameter in the transformation of the wave function, the position dependent effective mass problem is reduced to the solution of the Schr&ouml / dinger equation for the constant mass case. At the same time, the deformed Hulthen potential is solved for the position dependent effective mass case by applying the method directly. The Morse potential is also solved for a mass distribution function, such that the solution can be reduced to the constant mass case.

This thesis aims to investigate and discuss the conceptual and operational contexts of innovative approaches in the design of multi residential housing in Turkey over three selected cases. Flexibility, as an inclusive concept that encompasses adaptability and typological variety, is used to structure the framework of the discussion. The inquiry is based on the idea that flexibility and the associated concepts can be used to develop, in N. John Habraken&rsquo / s words, &ldquo / a new and challenging kind of architecture&rdquo / in the context of multi residential housing. The housing blocks designed by Ahmet G&uuml / lg&ouml / nen in Eryaman 3rd Stage, and those designed by Tuncay &Ccedil / avdar in the same stage, and Levent Loft 1 project designed by Tabanlioglu Architects are selected as cases. These projects advocate flexibility and also exemplify an innovative approach to design. The thesis introduces a conceptual framework that allows dealing with flexibility in the housing context, and then evaluates the selected cases by means of this conceptual framework.

This study focuses on preparing surface enhanced fluorescence (SEF) substrates for use in the enhancement of the emission signal of rhodamine B and fluorescein dyes. Fluorescence spectroscopy has been widely utilized owing to its high sensitivity. SEF is a process where the interactions of fluorophores with the localized surface plasmons of metal nanoparticles results in fluorescence enhancement, increased photostability and rates of system radiative decay which leads to a decreased lifetime. One of the most important factors of SEF studies is to provide a uniform distance between fluorophore and metal nanoparticle in a controlled manner / otherwise, F&ouml / rster resonance energy transfer takes place from fluorophore to metal nanoparticle and emission intensity of fluorophore is quenched. The spherical gold and silver nanoparticles were prepared using the well known and straightforward chemical reduction method, in which sodium citrate acted both as a reducing agent and a stabilizer around the formed nanoparticles. Silver and gold were chosen because of their high plasmon field enhancement. Since plasmon field strongly depends on the shape and size of the nanoparticles, the prepared nanoparticles were characterized using absorption spectroscopy and field emission scanning electron microscopy (FE-SEM). Prior to deposition of silver or gold nanoparticles on glass slides, the slides were derivatized by immersing them into an aqueous solution of 3-Aminopropylethoxysilane (APTES). Following derivatization, silver or gold nanoparticles were deposited by immersing the slides into the colloid mixture. Metal nanoparticle coated slides were characterized using absorption spectroscopy and field emission scanning electron microscopy (FE-SEM). Surface enhanced Raman scattering (SERS) measurements were carried out to observe the plasmon efficiency of the deposited nanoparticles. The SERS measurements were repeated for the duration of two weeks in order to check the stability of the plasmon efficiency. In this study, different types of materials (silica, zinc oxide, gold, stearic acid.) were employed as spacers to observe their effects on fluorescence enhancement. Physical vapor deposition (PVD) and Langmuir-Blodgett (LB) film deposition techniques were used for the formation of the spacer within the substrate. Fluorescence enhancement of rhodamine B and fluorescein was observed on the prepared SEF substrates. Obtained enhancement factors indicate that SEF substrates have the potential for sensitivity improvements of fluorescence sensing in many fields.

The study deals with investigation of acoustical characteristics of a hybrid silencer made up of a dissipative silencer and a quarter wave tube resonator. The theoretical and experimental analyses are performed to define acoustic characteristics of a simple expansion chamber and reactive perforated silencer, while the numerical and experimental solutions are presented for dissipative perforated silencer. Furthermore, the experiments and numerical solutions are extended to the hybrid silencer to find the effect of quarter wave tube resonator on the silencer performance. The experimental results of dissipative silencer are verified with theoretical solutions. The empirical expressions for acoustic impedance of perforation and filling material are presented in this study for use in a three-dimensional boundary element method (BEM). Besides, an experimental setup is also established to find the characteristic impedance and wavenumber of absorbing material to import BEM solution when the empirical expression cannot be used. The results found with BEM are compared by analytical and experimental results favorably.