Time evolution of the horseshoe vortex system forming around a bridge abutment

Scour forming around an isolated bridge abutment with curved end is investigated in this study. Clear water scour experiments are conducted for an abutment in a 25 m long sediment flume at a Reynolds number of 45000. 3D scour patterns forming around the abutments are obtained using an array of acoustic transducers along a grid refined up to 1-2 cm spacing at different stages of the scour. Detached Eddy Simulation (DES) is performed at the same channel Reynolds number for flat bed case (initiation of the scour) and for two deformed bed cases (intermediate stages of scour). Incoming flow in the simulations were fully turbulent containing unsteady velocity fluctuations. Variations in the structure and intensity of the horseshoe vortex system are investigated. At the initial stage of the scour the main and secondary horseshoe vortices undergo aperiodic bimodal oscillations. Those oscillations cause the horseshoe vortices to induce large bed shear stress values beneath them. As the scour hole starts forming secondary necklace vortex, HV2, gets closer to the primary necklace vortex, HV1, and merges with it at a location close to the abutment tip. © 2010 American Society of Civil Engineers

The effects of total knee arthroplasty on sleep quality

Introduction: Symptomatic osteoarthritis is one of the most common indications for total knee arthroplasty (TKA) operations. Pain in every stage of the disease causes sleep disturbances in patients. The primary objective of this study was to evaluate the effect of TKA on the quality of sleep in patients with symptomatic osteoarthritis. Materials and Methods: This retrospective, descriptive study was performed on 80 patients diagnosed with symptomatic osteoarthritis who underwent TKA. The patients responded to the Pittsburgh Sleep Quality Index (PSQI), which is widely used to evaluate sleep quality. Additionally, the effects of demographic and clinical variables such as age, gender, body mass index, smoking and alcohol consumption were also evaluated before and after surgery. Results: There was no correlation between demographic variables and PSQI scores pre- and postoperatively. There was a decrease in sleep quality on the sixth postoperative week compared to the preoperative period however this difference was not statistically significant. On the other hand, there was a statistically significant difference between preoperative and postoperative sixth month PSQI scores. Mean values of overall sleep quality and daily function were significantly higher in the postoperative sixth compared to the preoperative period (p<0.001) Conclusion: Treatment of symptomatic OA with TKA will improve sleep quality in the long term

The effect of hallux valgus surgery on quality of life

Background: Health-related quality of life (QOL) is defined as a patient’s subjective perception of his or her own health. Insufficient data exist on QOL of patients who undergo a hallux valgus (HV) operation. We used a 36-item short form survey (SF-36) to measure QOL of such patients. Our aim was to evaluate the effect of HV on QOL and to identify QOL determinants. Methods: Fifty patients who underwent surgery for HV between 2015 and 2017 were included in the study. The SF-36 questionnaire was applied to the patients before and after surgery. Patients’ medical records were examined to identify possible factors affecting QOL such as age, gender, body mass index, duration of symptoms, or smoking. Results: The mean age of the patients was 55.6 6 3.8 years, and 42 of the 50 patients were women. The mean duration of disease was 12 6 3.7 years. The surgery improved QOL scores for general health, emotional well-being, role limitations due to personal or emotional problems, physical functioning and bodily pain. However, the changes in scores for vitality and social functioning were not statistically significant. Lower postoperative QOL scores for emotional well-being and bodily pain were significantly associated with age and duration of the symptoms. Compared to the mean QOL of healthy adult Turkish population, all scores in subdimensions were lower. Conclusions: This study shows that HV in adults has a negative impact on general health, bodily pain, physical functioning, physical and emotional well-being rather than social well-being and vitality

Does THA affect sexual dysfunction in female patients with DDH?

Background: Sexual health, aside from reproduction, plays an important role in physical, intellectual, emotional and social facets of life. Developmental dysplasia of the hip (DDH) is a chronic orthopedic disease that has negative physical, social, and mental/spiritual effects, and lowers quality of life. However, no studies exist in the literature that focus on sexual function and health in patients with DDH. Methods: The preoperative and postoperative 6th month and 1st year sexual functions of women who underwent surgical treatment (total hip arthroplasty) for DDH (Crowe 1e4) (n:50) and their spouses (n:30) were evaluated with Arizona Sexual Experience scale (ASEX) questionnaire which evaluates sexual function in 5 categories such as desire, arousal, erection/lubrication, orgasm, and satisfaction. Results: The ASEX scores were 22.3 ± 3.5 preoperatively, 17.8 ± 2 at the 6th postoperative month, and 14.8 ± 1.3 at the 1st postoperative year. The decrease in the average score showed that sexual dysfunction existed in the preoperative period and sexual function was positively affected in the postoperative period over time. The ASEX scores of the patients younger than 35 in the postoperative 6th month had higher scores (P ¼.29). The sexual life of the husbands was not affected by the wives’ surgery, even though their spouses had a chronic condition causing functional difficulties. Conclusion: This study showed that the sexual life of women with DDH, who had been treated with total hip arthroplasty, was positively affected, whereas their husbands were unaffected. Further studies focusing on the effect of physiological and emotional factors, in addition to the surgical treatment, on sexual function are needed

Long-term results of total hip arthroplasty with transverse subtrochanteric shortening osteotomy in developmental high dislocation of the hip

In this study we aim to evaluate the functional and clinical results and complications of developmental high-dislocated hips after subtrochanteric transverse shortening osteotomy. The femoral osteotomies all fixed axially and rotationally by rectangular cementless stem. The acetabular components placed to the true acetabulum. Results of 50 primary cementless total hip arthroplasties in 28 patients all having Crowe 4 high dislocations were evaluated. Arthroplasties were performed in combination with a subtrochanteric transverse shortening osteotomy and Zweymüller femoral stem without any fixation instruments for the osteotomy. The acetabular component placed at the level of anatomic hip center. The mean follow-up was 102 months (72-132 months). The mean Harris Hip Score increased from 24.03 to 82.88 points at the time of final follow-up. Ten of the 50 hips had early or late minor complications and/or reoperations including debridement and irrigation. None of the subtrochanteric osteotomies were followed for nonunion or malunion, and there were no complications concerning the femoral site throughout the postoperative follow-up period

A comparison of time-switched transmit diversity and space-time coded systems over time-varying miso channels

This thesis presents a comparison between two transmit diversity schemes, namely space-time coding and time-switched transmit diversity (TSTD) over block-fading and time-varying multi-input single-output (MISO) channels with different channel parameters. The schemes are concatenated with outer channel codes in order to achieve spatio-temporal diversity. The analytical results are derived for the error performances of the systems and the simulation results as well as outage probabilities are provided. Besides, the details of the pilot-symbol-aided modulation (PSAM) technique are investigated and the error performances of the systems are analyzed when the channel state information is estimated with PSAM. It is demonstrated using the analytical and simulation results that TSTD have a comparable error performance with the space-time coding techniques and it even outperforms the space-time codes for some channel parameters. Our results indicate that TSTD can be suggested as an alternative to space-time codes in some time-varying channels especially due to the implementation simplicity.M.S. - Master of Scienc

Synthesis and optimization of boron nitride nanotubes for stable aqueous dispersions

As structural analogues of carbon nanotubes (CNT), boron nitride nanotubes (BNNT) possesses extraordinary mechanical, electrical, thermal and optical properties. These unique properties, makes them promising materials applications in composite, hydrogen storage, radiation shielding, biomaterials. However, difficulties in high yield BNNT synthesis and obtaining stable dispersions of BNNTs in aqueous media remain as main challenges. This thesis research focuses on the BNNT synthesis and optimization thereof in addition to preparation of stable aqueous dispersions of BNNTs. High yield synthesis of BNNTs on Si wafers and BNNFs as well as floating BNNT form by modified growth vapor trapping-BOCVD method in conventional tube furnace at 1200 °C were accomplished in this research. Synthesis of BNNTs were optimized in terms of temperature, catalyst ratio, catalyst amount, ammonia flow, reaction time and system parameters which allowed high yield synthesis of good quality BNNTs with vacuum free, low cost, novel growth vapor trapping-BOCVD route. As-synthesized BNNTs were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, Fourier Transform Infra-Red spectroscopy (FTIR) and electron energy loss spectroscopy (EELS). Following the successful synthesis of BNNTs, BNNT synthesis from boron minerals were investigated. Boron minerals Ulexite and Etidot-67, gifted from ETİ Maden İşletmeleri, were used as boron precursors for the synthesis of floating BNNTs in this research. Assynthesized BNNTs were characterized by SEM and RAMAN spectroscopy. Two modification approaches were utilized for the surface modifications of BNNTs: Covalent functionalization and non-covalent functionalization. In covalent functionalization approach, BNNT’s surfaces were hydroxylated by nitric acid treatment and ozone treatment, which reduces the van der Waals forces between nanotubes. Moreover, hydroxyl groups on the surface of BNNTs can be used as starting spots for the further functionalization. In-non covalent functionalization approach, BNNTs were wrapped with ionic surfactants and polymers (b-PEI (branched polyethyleneimine) and poly(allylamine hydrochloride) (PAH) via π-π interaction to prevent agglomeration of BNNTs and dispersed in aqueous media. Dispersions of as-functionalized BNNTs characterized by Fourier Transform Infra-Red spectroscopy (FTIR) and dynamic light scattering spectroscopy (DLS). BNNT thin film production by dip LbL method was investigated. LbL method allows high control over the architecture of thin film in addition to film thickness. BNNT dispersions were used in combination with b-PEI and PSS Poly(styrenesulfonate) for the production of BNNT thin films on glass substrates. Different pH values of as-prepared dispersions were tested in order to achieve 5 bl (bilayer) and 10 bl thick BNNT thin films by dip LbL method. Synthesis parameters of BNNTs were successfully optimized and synthesis of BNNTs were achieved. As-synthesized BNNT’s surfaces were modified with covalent and noncovalent functionalization methods and stable aqueous dispersions of BNNTs were achieved. We found that, non-covalent functionalization of BNNTs allows BNNTs to be dispersed in aqueous media with good dispersion stability

Development of animal frize on İonic architecture at Archaic Age

Arkaik Dönem İon mimarlığında bezeme unsuru olarak kullanılmış olan hayvan frizleri bu çalışmanın ana konusunu oluşturmaktadır. İon sanatını daha iyi anlama adına, mimari eserler yanında, İon sanatının ürünleri olan farklı üsluplardaki seramikler, plastik eserler, Klazomenai lahitleri, kent sikkeleri ve diğer küçük buluntu örnekleri de konu kapsamında detaylıca incelenmiştir. İon sanatındaki hayvan tasvirlerine ışık tutması için, ilk ortaya çıktığı dönemlerden başlayarak, çalışmanın ana konusu olan Arkaik Döneme kadar uzanan bir süreçte, farklı kültürlerde görülen hayvan betimleri ayrı başlıklar altında sunulmuştur. Paleolitik dönemden başlayarak Arkaik Dönem sonuna kadar, Anadolu, Mezopotamya, Yunanistan, Mısır ve Ege havzasındaki kültürlere ait hayvan betimli mimari, seramik, plastik eserler ve diğer buluntular incelenmiştir. Farklı kültürlerdeki hayvan betimlerinin birbirleri ile olan ilişkileri, kendi kültürleri içinde taşıdığı anlamlar ve tasvir biçimleri hakkında bilgiler verilerek değerlendirilmeler yapılmıştır. Arkaik Dönem Anadolu sanatındaki hayvan betimleri ise, bölgeler dikkate alınarak ayrı başlıklar altında ele alınmış, bölgeler arası benzerlikler ve ayrılan yönler vurgulanarak sanata olan katkıları değerlendirilmiştir. Çalışma haritalar, tablolar, grafiklerle ve levhalarla desteklenerek konunun daha kolay anlaşılması sağlanmıştır.The use of animal imagery to decorate freizes within the Archaic Ionian architectural period is the main subject of this study. In order to understand the Ionian arts and architecture with greater appreciation and understanding the differing styles to be seen within ceramics, sarcophagus and other small objects which have been found are incorporated into this work. In order to throw some light onto the subject of animal imagery within the Ionian arts, one must begin from the first period, the animal images which are seen within different cultures from this period are to be found under different sections. The animal imagery to be seen within architecture, ceramics and other remnants from the Paleolithic period to the Archaic period within the cultures of Anatolia, Mesopotamia, Greece, Egypt and the Aegean basins have been examined. The relationship between the animal imagery of differing cultures, their meaning, value within their own cultures and the data about their defining styles have been given and evaluated. In addition the animal imagery which is to be seen within the Archaic period of Anatolian arts has been undertaken in separate sections; considering the similarities and differences of animal depiction within different areas, and the emphasis which this takes and the benefits to the arts of the region have been evaluated. The study was supported with maps, charts, graphics and tablets in order to make the subject more understandable

Verleich Corporate Governance Systeme zwischen Deutschland und USA und deren Auswirkungen auf Managergehälter

Das Thema „Corporate Governance“ wird sowohl in Europa als auch in den USA intensiv diskutiert. Die Entlohnung von Topmanagern ist in dieser Debatte nicht unwesentlich. Trotz Finanzkrise haben hohe Bonuszahlungen an Topmanager die Diskussion verschärft was sowohl in der Gesellschaft als auch in der Politik folgende Frage aufwirft: Welche Auswirkungen hat die globale Krise tatsächlich auf die Managementvergütung? Diese Frage soll im Laufe des Vergleichs der Corporate Governance Systeme in Deutschland und den USA und die unterschiedlichen Vergütungsinstrumente in beiden Ländern beantwortet werden. Welche Absichten verfolgen die Unternehmereigentümer auf ihre Manager bzw. auf die langfristige Bindung der Manager auf Unternehmensziele? Da die Vergütungspraktiken in den USA eine Vorreiterrolle darstellen, sollen diese Modelle eine mögliche Antwort auf die Gesamtentwicklung der Managergehälter geben. Es werden die Vergütungsinstrumente und die Entwicklung der Vergütungshöhe der DAX 30 Unternehmen zwischen den Jahren 2005 und 2009 analysiert und die aktienorientierte Managementvergütung sowie deren kritischen Folgen untersucht werden