Essays in empirical asset pricing

This dissertation contains three articles. In the first article, I review the literature on liquidity. I focus on various liquidity proxies and their effects on the equity returns while restricting the review to the set of top journals in finance since this literature is quite immense. In the second article, I investigate the relationship between expected returns and liquidity measures in Borsa Istanbul. Firm-level cross-sectional regressions indicate that there is a positive relationship between various illiquidity measures and one-month to six-month ahead stock returns. Findings are robust after using different sample periods and controlling for well-known priced factors such as market beta, size, book-to-market and momentum. The portfolio analysis reveals that stocks that are in the highest illiquidity quintile earn 7.2% to 19.2% higher risk-adjusted annual returns than those in the lowest illiquidity quintile. The illiquidity premium is stronger for small stocks and stocks with higher return volatility and it increases (decreases) during periods of extremely low (high) market returns. In the third article, I investigate the stock return exposure to various illiquidity risk factors through alternative measures of factor betas and the performance of factor betas in predicting the cross-sectional variation in stock returns. As a parametric test, a two-step procedure is utilized to directly calculate the monthly factor betas in the first stage and then, the sensitivity of stock returns to these previously estimated factor betas is calculated in the second. The regression results show that there exists a significantly positive link between illiquidity beta and future stock returns. The results are robust after controlling for market, size, book-to-market and momentum factors. The portfolio analysis reveals that stocks in the high-beta portfolio generate about 5% higher annual returns compared to stocks in the low-beta portfolio

An Overview of Rare and Unusual Clinical Features of Bietti’s Crystalline Dystrophy

Bietti’s crystalline dystrophy (BCD) is a rare disease presenting with the appearance of intraretinal crystalline deposits and varying degrees of chorioretinal atrophy commencing at the posterior pole. Within time, intraretinal crystals gradually disappear and chorioretinal atrophy extends beyond the macula even resulting in complete chorioretinal atrophy. Concomitant corneal crystals can be noted in 1/2 - 1/3 of the patients, and the presence of corneal crystals is not a must for establishing the diagnosis. For the past decade, genetic evaluations and newer imaging modalities expand our knowledge about the disease. CYP4V2 gene is found to be the gene responsible for the disease process and new mutations are still being described. Modern imaging modalities, such as a spectral domain optical coherence tomography (SD-OCT) shed light on the anatomic features of the disease. By this, we reiterate the rare and unusual clinical features of BCD

An Overview of Rare and Unusual Clinical Features of Bietti’s Crystalline Dystrophy

Bietti’s crystalline dystrophy (BCD) is a rare disease presenting with the appearance of intraretinal crystalline deposits and varying degrees of chorioretinal atrophy commencing at the posterior pole. Within time, intraretinal crystals gradually disappear and chorioretinal atrophy extends beyond the macula even resulting in complete chorioretinal atrophy. Concomitant corneal crystals can be noted in 1/2 - 1/3 of the patients, and the presence of corneal crystals is not a must for establishing the diagnosis. For the past decade, genetic evaluations and newer imaging modalities expand our knowledge about the disease. CYP4V2 gene is found to be the gene responsible for the disease process and new mutations are still being described. Modern imaging modalities, such as a spectral domain optical coherence tomography (SD-OCT) shed light on the anatomic features of the disease. By this, we reiterate the rare and unusual clinical features of BCD

A new ratio-metric pH probe, "ThiAKS Green" for live-cell pH measurements

Deviation of the H+ concentration from optimum values within the organelles is closely associated with irregular cellular functions that cause the onset of various diseases. Therefore, determining subcellular pH values in live cells and tissues is valuable for diagnostic purposes. In this study, we report a novel ratiometric fluorescence probe 1H-pyrazole-3-carboxylic acid, 4-(benzo[d]thiazol-2-yl)-3-(2,4-dihydroxy-3-methylphenyl)-1H-pyrazole-5-carboxylicacid4-(2-benz othiazolyl)-5-(2,4-dihydroxy-3-methylphenyl), to which we will refer as ThiAKS Green (Thiazole AKyol shifting green), that is pH sensitive. The results presented here show that the probe can penetrate the cell membrane in less than 30 minutes and does not show any detectable toxicity. The measured color shifts up on pH change are linear and most significant around physiological pH (pKa=7.45), thus making this probe suitable for live-cell imaging and intracellular pH measurements. During the long-incubation periods following the application of the probe and the fluorescent microscopy measurements, it shows stable properties and is easy to detect in live cells. In conclusion, the results suggest that ThiAKS Green can be used to obtain precise information on the H+ distribution at various compartments of the live cells.Golg

Experimental Investigation of Sheet Metal Forming Using a Recyclable Low Melting Point Alloy Tool

Due to intense competition in automotive industry, new car models have to be launched as quickly as possible. A re-evaluation of the design and development phases has reshaped product development in order to get product earlier than competitors. Prototype production is one of the longest stages of product development due to physical verification activities. Shortening of this process will provide more opportunity to get project schedule earlier. Rapid prototype technologies are usually used as a guide for visual and packaging analysis. However, there is a requirement to use these parts for functional testing as well. Developing alternative rapid tooling methods which shorten the physical prototype production phase, while adequately supporting visual, packaging and functional aspects of sheet metal forming, can lead to considerable savings in vehicle prototype development. In this study, sheet metal prototype part using recyclable low melting point alloy was experimentally investigated by analysing dimensional conformance of tools and parts. In addition to wear performance, thickness reduction was investigated for stamped parts. Abstract in German: Untersuchung der Metallblechumformung unter Verwendung eines recyclingfähigen Werkzeuges aus einer niedrigschmelzenden Legierung. Aufgrund des intensiven Wettbewerbs in der Automobilindustrie müssen neue Fahrzeugmodelle so schnell wie möglich auf den Markt gebracht werden können. Um ein Produkt früher als die Wettbewerber fertig zu haben, wurde die Produktentwicklung durch eine Re-Evaluierung des Designs und der Entwicklungsphasen verändert

Remodeling in Patients with in Situ Fixation for a Slipped Capital Femoral Epiphysis

Objective: This study has investigated the amount of bone remodeling in patients with a slipped capital femoral epiphysis (SCFE) treated with in situ fixation until closure of the epiphysis and the factors affecting remodeling. Method: Patients who underwent surgery for SCFE between January 2010 and January 2015 were retrospectively screened: Twenty-four male and 7 female patients (mean age 12.6 +- 1.9 years) were included in the study. Gender, age, history, and laterality of trauma, duration of hip pain (acute, chronic, acute on chronic background), and hip radiographs were evaluated. The Southwick and alpha angles were measured, and the factors affecting remodeling were assessed. The statistical analyses were conducted using SPSS 25.0 (IBM Corp., Armonk, NY); 95% confidence levels were calculated and p < 0.05 was considered to indicate statistical significance. Results: The preoperative displacement angles measured on the anteroposterior and lateral radiographs were 15.03° +- 9.1° and 25.93° +- 14.1° and at the last follow-up they were 11.63° +- 8.7° and 21.6° +- 12.1°, respectively. The alpha angles measured on the lateral radiographs preoperatively and at the end of follow-up were 52.33° +- 11.6° and 47.87° +- 11.8°, respectively. Significant remodeling was reflected in the angles measured on the anteroposterior and lateral X-ray images. Greater preoperative displacement angle was associated with less remodeling. Conclusion: Preoperative displacement affects the degree of postoperative remodeling. In patients with severe epiphyseal displacement, open reduction is an option but in situ pinning should be considered in that it is less invasive and more physiological

The “Other” Neglected Diseases in Global Public Health: Surgical Conditions in Sub-Saharan Africa

Doruk Ozgediz and Robert Riviello discuss the burden of premature death and disability and the economic burden of surgical conditions in Africa

Single-material MoS2 thermoelectric junction enabled by substrate engineering

To realize a thermoelectric power generator, typically, a junction between two materials with different Seebeck coefficients needs to be fabricated. Such differences in Seebeck coefficients can be induced by doping, which renders it difficult when working with two-dimensional (2d) materials. However, doping is not the only way to modulate the Seebeck coefficient of a 2d material. Substrate-altered electron–phonon scattering mechanisms can also be used to this end. Here, we employ the substrate effects to form a thermoelectric junction in ultrathin, few-layer MoS2 films. We investigated the junctions with a combination of scanning photocurrent microscopy and scanning thermal microscopy. This allows us to reveal that thermoelectric junctions form across the substrate-engineered parts. We attribute this to a gating effect induced by interfacial charges in combination with alterations in the electron–phonon scattering mechanisms. This work demonstrates that substrate engineering is a promising strategy for developing future compact thin-film thermoelectric power generators

Epidemiology of injuries presenting to the national hospital in Kampala, Uganda: implications for research and policy

BackgroundDespite the growing burden of injuries in LMICs, there are still limited primary epidemiologic data to guide health policy and health system development. Understanding the epidemiology of injury in developing countries can help identify risk factors for injury and target interventions for prevention and treatment to decrease disability and mortality.AimTo estimate the epidemiology of the injury seen in patients presenting to the government hospital in Kampala, the capital city of Uganda.MethodsA secondary analysis of a prospectively collected database collected by the Injury Control Centre-Uganda at the Mulago National Referral Hospital, Kampala, Uganda, 2004-2005.ResultsFrom 1 August 2004 to 12 August 2005, a total of 3,750 injury-related visits were recorded; a final sample of 3,481 records were analyzed. The majority of patients (62%) were treated in the casualty department and then discharged; 38% were admitted. Road traffic injuries (RTIs) were the most common causes of injury for all age groups in this sample, except for those under 5 years old, and accounted for 49% of total injuries. RTIs were also the most common cause of mortality in trauma patients. Within traffic injuries, more passengers (44%) and pedestrians (30%) were injured than drivers (27%). Other causes of trauma included blunt/penetrating injuries (25% of injuries) and falls (10%). Less than 5% of all patients arriving to the emergency department for injuries arrived by ambulance.ConclusionsRoad traffic injuries are by far the largest cause of both morbidity and mortality in Kampala. They are the most common cause of injury for all ages, except those younger than 5, and school-aged children comprise a large proportion of victims from these incidents. The integration of injury control programs with ongoing health initiatives is an urgent priority for health and development