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Investigation of ALCAM's role in glioblastoma senescence
(Bilkent University, 2024-06) Oğurlu, Tuba Sena
Glioblastoma (GBM) is a type of glioma that is the most common brain tumor in the Central Nervous System. Based on this classification, it is the highest-grade astrocytoma (grade IV), highly aggressive and invasive brain cancer. The primary treatment for GBM involves surgical resection to remove as much of the tumor as possible. This is typically followed by radiotherapy and concurrent temozolomide (TMZ) chemotherapy. Despite these multimodal approaches, the prognosis for GBM patients remains poor, with a median survival of approximately 12-16 months. It is already known that the high invasiveness causes the cancer to reach other tissues in the body. If the cells could migrate to other regions but couldn't proliferate, this would increase the lifespan following the diagnosis. Therefore, one of the most important reasons why these treatments are not effective is the fact that cells can escape senescence induced by TMZ. New genetic tools or targets are needed to help to keep the cells in senescence state or to induce senescence more effectively. Here, in this study, we wanted to investigate the role of Activated Cell Adhesion Molecule (ALCAM) in GBM senescence. In the literature, it has been shown that GBM patient survival decreases with the increased ALCAM level. Moreover, in patient-derived xenografts, cells with overexpressed soluble ALCAM showed more aggressiveness. On the contrary, when ALCAM was decreased in GBM cell lines, the colony formation ability increased. Therefore, the role of ALCAM in senescence and especially in GBM senescence, if there is, has remained elusive. To shed light on this unclarified relationship, we used ALCAM targeting small interfering ribonucleic acid (siRNA) and constructed plasmid overexpressing it to manipulate the ALCAM gene level in GBM cells. Expression levels of senescence markers and SA-βgal staining percentage were investigated upon these manipulations. Although significant changes were observed in senescence markers, we cannot say they were consistent or relatable. There is a need for a more comprehensive study to understand the correct relationship. Moreover, conditions like tumor microenvironment, stem cell subpopulation percentage and combinatorial effects should be considered.
An early monetization?: tracing the mukâta‘a system back to the reign of Mehmed II
(Bilkent University, 2024-06) Taşpınar, Furkan
This thesis examines the extent of monetization of the Ottoman economy during the fifteenth and early sixteenth centuries. At the core of the research lies the mukâta‘a system since it served as the primary mechanism for providing cash flow into the Ottoman treasury and, therefore, it was a key indicator of monetization. The archival data used in the thesis demonstrate that the mukâta‘a system, along with tax farming, was empire-wide established and functional in receiving revenue from many production sectors and tax items such as mining, rice plantation, salt marsh, sheep tax, poll tax, market tax, and more during this period. These data also reveal the high amount of precious metals in circulation in the Ottoman market throughout the fifteenth and early sixteenth centuries. Thus, the thesis argues that the Ottoman economy monetized in certain sectors a century earlier than current scholarship suggests. Furthermore, the thesis also argues that the capital accumulation resulting from this monetization might be mainly limited to the Ottoman central treasury, and tax farmers might not be capable of accumulating capital due to the strict bureaucratic control and sanctions imposed by the Ottoman central administration during the fifteenth and early sixteenth centuries. To understand this relationship between the state and tax farmers, the thesis also examines the roles of central and local imperial agents within the mukâta‘a system alongside the identities and social networks of the tax farmers.
Women’s lifestyle and wellness visibilities on instagram: a critical analysis from a feminist perspective
(Bilkent University, 2024-06) Güç, Çağla
Wellness influencers and accounts on Instagram have reached large followers, a majority of which consist of women, by gathering engaging content that resonates with users seeking guidance on various topics and overall lifestyle improvement. Through a thematic content analysis of the most recent 200 posts from 20 of wellness and lifestyle Instagram accounts, this research examines the messages, communication strategies, and underlying feminist ideals presented to followers. Results indicated that the content fosters feelings of inadequacy for women, especially since they advise women to constantly self-improve. Although these accounts claim to aspire for the goal of empowerment, they often align with media-visible feminist perspectives characterized by postfeminism, neoliberal feminism, and popular feminism. They employ the term feminism as a motivational and trendy concept, which results in hollowing the term’s meaning and certainly not following feminist ideals.
Relation of perceptual fluency with metamemory judgments and recognition memory
(Bilkent University, 2024-05) Dalkıran, Sultan Rengin
Previous research has shown that perceptual fluency differentially affects metamemory judgments and actual recognition performance. In this sense, the perceptual-fluency hypothesis asserts that fluent items are considered more memorable and are likely to receive higher metamemory judgments than disfluent items, which is replicated in multiple studies. Despite a demonstrated positive effect of perceptual fluency on metamemory judgments, the relationship between perceptual fluency and recognition memory performance is less clear. Therefore, in this study, we aimed to further investigate the distinctive effects of perceptual fluency on metamemory judgments and actual recognition performance for pictures. Respectively, in Experiment 1, subjects (n = 30) were presented with blurred or clear pictures and prompted with judgments of learning (JOLs) ratings at study, followed by a recognition test. In Experiment 2, our main focus was on the direct association between perceptual fluency and actual recognition performance. Hence, the second experiment was similar to the first one except subjects (n = 48) were not prompted with JOLs and multiple sources of manipulations (blurriness and inversion) were implemented to induce perceptual disfluency. The results showed that neither metamemory judgments nor actual recognition performance significantly differed in response to perceptual fluency. Thus, in contrast to many other studies, the current study failed to support the perceptual fluency hypothesis even though our results about actual recognition performance aligned with past research.
Three dimensional electrode integration on microwave resonator sensors for microparticle sensing in microfluidics
(Bilkent University, 2024-06) Alataş, Yağmur Ceren
Position dependency of the particle-induced signal can be mitigated by using a 3-dimensional (3D) electrode configuration at the sidewalls of the microfluidic channel in electrical sensors. The first method to obtain 3D electrodes was filling Galinstan, Galium-Indium alloy with low melting point, to dead-end PDMS cavities at the sidewalls of a microfluidic channel positioned on a split ring resonator (SRR). Due to electrical contact between coplanar resonator electrodes and Galinstan cavities, the electric field between coplanar resonator electrodes was extended to form a uniform electric field along the height of the microfluidic channel. Galinstan was used in this application due to its low melting point, non-toxicity, and high conductivity. This architecture was used for size-based classification of 20-and 30\textmu m polystyrene (PS) microparticles without any post-processing for particle trajectory. However, the signal-to-noise ratio (SNR) was low due to the presence of PDMS spacers between the Galinstan cavities and the microfluidic channel, which were placed to avoid leakage of liquid metal into the microfluidic channel. In the later method, 3D electrodes made of solid material, epoxy-based, negative photoresist SU8, were fabricated and positioned inside a microfluidic channel to boost the signal-to-noise ratio. SU8 pillars with tens of micrometers height were patterned at the sensing region and metalized using sputter deposition to form a conformal profile on the electrodes. A fused silica substrate containing the SU8 microelectrodes, microfluidic channel, and coplanar connection electrodes was mounted on a microstrip transmission line resonator on PCB. The electric field on the resonator electrodes was extended to form a uniform electric field inside the microfluidic channel between the SU8 microelectrodes through wirebonding on connection electrodes. This sensor architecture was also used for size-based classification of 12-and 20\textmu m polystyrene microparticles without any trajectory correction. As a result of positioning 3D electrodes in direct contact with the microfluidic channel, the signal-to-noise ratio increased by 10 folds. Furthermore, a split ring resonator was integrated with a Coulter counter operating at low frequencies to measure the size and dielectric permittivity of a microparticle simultaneously. SU8 microelectrodes were fabricated at the tip of low and high-frequency sensing electrodes, positioned inside the microfluidic channel, forming the sensing region. The signals induced in the split ring resonator and Coulter counter can be simultaneously processed to get information about the size and type of the particle. Polystyrene and polyethylene microparticles with different dielectric permittivity and size were differentiated with this sensor. It was realized that polyethylene microparticles contained additives, which were not explicitly stated, however, the presence of titanium dioxide was detected using energy-dispersive X-ray spectroscopy (EDX). It was concluded that as a result of using a microwave resonator, it was possible to detect the presence of titanium dioxide inside the polyethylene microparticles and differentiate polystyrene and polyethylene particles.
Multidimensional liminal threshold of the city of Ankara: The Namazgâh Hill
(Bilkent University, 2024-06) Dağlı, Muhammed Said
Namazgâhs, which can be seen in many Ottoman cities, are open-air places of worship and they stand out as an overly comprehensive and ambivalent concept that can vary in their functions, qualities and quantities. Throughout its history, the Namazgâh and the Namazgâh Hill in Ankara have served different functions: as a gathering place, a place of worship, a cemetery and a gateway to the city. While the origins of this Namazgâh remain a mystery, these various functions became particularly evident during the War of Independence, a critical period that contributed to the establishment of the new Republic. The aim of this thesis is to compile existing sources on the Namazgâh Hill, to determine as much as possible which functions it assumed and under what circumstances, to show that it is a multidimensional liminal space for the city of Ankara, to explain that it not only hosted liminal transformations but also underwent liminal transformations itself, and as a result, to create a comprehensive historical narrative of the site. For this purpose, the Ottoman and Republic State Archives, paintings, engravings, photographs, newspapers of the period, the memories of people who used to live or have visited Ankara, and ethnographic studies about this city will be used.
A fictionalist social ontology
(2024-05) Bakkal, Erim
In this thesis, I explore how a fictionalist approach can be applied to social ontology, especially for conferred kinds, in the context of action explanation and prediction by comparing this view with various realist views. Chapter 1 is concerned with clarifying constitution accounts and the criteria for comparison. Chapter 2 gives three different kinds of problems against this realist view, which makes this view less credible. Chapter 3 introduces conferralist accounts. Chapter 4 will deal with the question of whether conferralist accounts can solve these problems. I will argue that even if the second problem is solved, the first and third problems still arise in conferralism. In Chapter 5, I propose a fictionalist social ontology. Thus, in Chapter 6, I argue that social fictionalism solves the problems in question.
Longevity and circadian rhythm in Caenorhabditis elegans: the impact of lithium chloride
(Bilkent University, 2024-06) Temirci, Elif Sena
Lithium chloride (LiCl) is a popular treatment for various neurological disorders, especially bipolar disorders. While its complete mechanism of action remains partially elucidated, LiCl has been found to support new memory formation by triggering the construction of new neurons, reducing senescence, and regulating the circadian rhythm, particularly in bipolar patients, where it counteracts their abnormally fast biological clock. The circadian rhythm is vital in determining efficiency, understanding energy consumption, and biochemical balance for all organisms. This
rhythm includes regulating body functions by the day/night cycle. Caenorhabditis elegans (C. elegans) is one of the most robust organisms for modeling circadian rhythm, although it lives in the soil. Therefore, by employing C. elegans as a model system, valuable insights could be gained for these complex processes. This study aims to elucidate the complex relationship between LiCl, circadian rhythms, and longevity, as disruptions in these pathways are implicated in neurodegenerative diseases and age-related cognitive and motor decline. In this project, white light was employed to manipulate the circadian rhythm in C. elegans, with one group additionally receiving LiCl treatment in addition to light exposure. The study focused on longevity, response to environmental factors, and circadian rhythm. To elucidate the effect on longevity, lifespan measurements showed that LiCl treatment extended the lifespan of C. elegans under both light and dark conditions, with a shorter lifespan observed in the light. Additionally, when comparing the effect of specific developmental time points, the signs of aging appeared later in the dark compared to the light. The differential gene expression of longevity genes suggested that LiCl treatment could impact gene expression, particularly the age-1 gene, but not the daf-16 gene. Furthermore, the response to environmental changes was examined imilarly and it was observed that C. elegans responded to the circadian rhythm disruption caused by light and LiCl administration. In conclusion, this study suggests that LiCl treatment has the potential to mitigate the adverse effects of circadian rhythm disruptions and reverse the aging process of C. elegans.
Dare to share? how anti-disinformation policies affect online news-sharing behavior in Türkiye
(Bilkent University, 2024-05) Küçükoruç, Selin
For the past decades, governments and social media companies have attempted to combat the spread of misinformation online by developing new regulations around online technologies. While these attempts have successfully curbed the spread of misinformation in many instances, there have also been cases where such regulations have violated the freedom of expression due to the uncertainty surrounding the definition of misinformation (Cipers et al., 2023). This thesis aims to explore how these strategies to combat misinformation affect the way ordinary citizens engage with news online in an authoritarian-leaning context. In doing so, it investigates the impact of recent counter-misinformation regulation in Turkiye, publicly known as the disinformation or censorship law, on news-sharing behavior. Employing a 2x2 between-subjects online survey experiment among 228 Turkish college student, the study seeks to understand whether exposure to information about the law and the mode of online identity (anonymous vs. real) affects individuals’ news-sharing tendencies. Although the salience of the law and the different modes of online identity does not significantly affect news-sharing attitudes as a model, the salience of the law alone has a significant negative relationship with sharing likelihood when all control variables were included in the analysis. Overall, the findings highlight the importance of striking a balance between countering misinformation and protecting freedom of expression online.
Generating tree method and applications to pattern-avoiding inversion sequences
(Bilkent University, 2024-05) Gezer, Melis
An inversion sequence of length n is an integer sequence e = e1 · · · en such that 0 ≤ ei < i for each 0 ≤ i ≤ n. We use In to denote the set of inversion sequences of length n. Let [k] := {0, 1, · · · , k − 1} denote the alphabet and τ be a word of length k over this alphabet. A pattern of length k is simply a word over the alphabet [k]. We say an inversion sequence e ∈ In contains the pattern τ of length k if it contains a sub-sequence of length k that is order isomorphic to τ; otherwise, e avoids the pattern τ . For a given pattern τ , we use In(τ ) to denote the set of all τ -avoiding inversion sequences of length n. Firstly, we review the enumeration of inversion sequences that avoid patterns of length three. We then study an enumeration method
based on generating trees and the kernel method to enumerate pattern-avoiding inversion sequences for general patterns. Then, we provide sampling
algorithms for pattern-avoiding inversion sequences and apply them to some specific patterns. Based on extensive simulations, we study some statistics such as the number of zeros, the number of distinct elements, the number of repeated elements, and the maximum elements. Finally, we present a bijection between In(0312) and In(0321) that preserves these statistics.