Istanbul Technical University
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AI-Driven Handover Management and Load Balancing Optimization in Ultra-Dense 5G/6G Cellular Networks
No full textThis paper presents a comprehensive review of handover management and load balancing optimization (LBO) in ultra-dense 5G and emerging 6G cellular networks. With the increasing deployment of small cells and the rapid growth of data traffic, these networks face significant challenges in ensuring seamless mobility and efficient resource allocation. Traditional handover and load balancing techniques, primarily designed for 4G systems, are no longer sufficient to address the complexity of heterogeneous network environments that incorporate millimeter-wave communication, Internet of Things (IoT) devices, and unmanned aerial vehicles (UAVs). The review focuses on how recent advances in artificial intelligence (AI), particularly machine learning (ML) and deep learning (DL), are being applied to improve predictive handover decisions and enable real-time, adaptive load distribution. AI-driven solutions can significantly reduce handover failures, latency, and network congestion, while improving overall user experience and quality of service (QoS). This paper surveys state-of-the-art research on these techniques, categorizing them according to their application domains and evaluating their performance benefits and limitations. Furthermore, the paper discusses the integration of intelligent handover and load balancing methods in smart city scenarios, where ultra-dense networks must support diverse services with high reliability and low latency. Key research gaps are also identified, including the need for standardized datasets, energy-efficient AI models, and context-aware mobility strategies. Overall, this review aims to guide future research and development in designing robust, AI-assisted mobility and resource management frameworks for next-generation wireless systems.https://doi.org/10.3390/technologies13070276https://doaj.org/article/b60cc232c4114c209fe2eea2a789064
Assessment of PM2.5 Variation and Estimation of Mortality Attributable to Long-Term PM2.5 Exposure Using the AirQ + Model in Kocaeli, Türkiye
No full texthttps://doi.org/10.1007/s11270-025-08554-
Multidisciplinary insights into zeolite and clay formation in hydrothermally altered volcanic rocks of Çubuk, Turkey
No full textAbstract The present study addressed the influence of lithological variability on hydrothermal alteration processes in the Çubuk region of Ankara, recognized globally for its agate occurrences. The objective was to clarify how differing host rocks, tuff and ignimbrite in Karadana, and perlitic units in Yukarıemirler, affect secondary mineral formation and alteration pathways. A combination of mineralogical (X-ray diffraction, Fourier-transform infrared spectroscopy, field-emission scanning electron microscopy) and geochemical (energy-dispersive X-ray spectroscopy, whole-rock geochemistry, δ 18 O–δD) methods was utilized to characterize alteration assemblages and fluid conditions. The alteration sequence progressed through five stages, beginning with unaltered volcanic rocks. In the second stage, smectite-group clays, particularly montmorillonite, were formed under mildly alkaline and low-temperature conditions (pH 7.5–9.0; T 43–50°C). This initial clay formation was followed by zeolitization along two distinct pathways: clinoptilolite crystallized (K-rich, Si/Al ~4.2) in the Karadana tuff–ignimbrite units, while heulandite formed (Ca-rich, Si/Al ~2.7) in the perlitic host rocks of Yukarıemirler. These variations are attributed to differences in host-rock composition, permeability, and hydrothermal fluid chemistry. In more advanced stages, mordenite and chabazite precipitated under progressively higher pH and temperature conditions (pH 9.5–10.0; T 70–80°C). In the final stage, opal–quartz formed due to silica supersaturation triggered by a drop in pH, despite rising temperatures (pH ~8.5–9.0; T ~250°C). The paragenetic sequence confirms that clay mineral formation preceded zeolitization in both zones. Variations in zeolite types reflect strong lithological and hydrochemical controls, as well as the origin of the hydrothermal fluids; clinoptilolite formation in Karadana is associated with Na- and K-rich supergene fluids, while Ca-rich hypogene fluids promoted heulandite precipitation in Yukarıemirler. This study presents the first detailed paragenetic model for zeolite–clay alteration in the Çubuk volcanic system and offers new insights into post-caldera hydrothermal evolution in Central Anatolia.https://doi.org/10.1017/cmn.2025.1001
Fabrication of a Sensitive and Straightforward Electrochemical Sensor Utilizing Molecularly Imprinted Polymers for the Targeted Detection of the Antiretroviral Drug Ritonavir
No full text<title>Abstract</title> <p>This study developed a new sensor technology utilizing molecularly imprinted polymers (MIPs) for the electrochemical detection of ritonavir (RTV), a protease inhibitor for HIV treatment. Since RTV is also a major inhibitor of the P450 3A4 isoenzyme, it is often given with other medications. Hence, assessing the therapeutic effectiveness of RTV requires precise measurement of RTV in complicated biological matrices and complex mixtures. On the surface of the glassy carbon electrode (GCE), a polymeric layer was created utilizing RTV as the template molecule, methacrylic acid (MAA) as the functional monomer, and aniline in phosphate buffer (pH 7). The morphological and electrochemical properties of the RTV/ANI-co-MAA@MIP-GCE sensor were evaluated through scanning electron microscopy (SEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The sensor demonstrated a linear detection range for RTV using a redox probe (5.0 mM [Fe(CN)<sub>6</sub><sup>]−3/−4</sup>) between 1.0 × 10<sup>− 12</sup> M and 1.5 × 10<sup>− 11</sup> M, with a limit of detection (LOD) and limit of quantification (LOQ) for standard solutions determined to be 2.75 × 10<sup>− 13</sup> M and 9.18 × 10<sup>− 13</sup> M, respectively. The sensor was then successfully used to identify RTV in commercial serum samples and tablets, producing acceptable recovery results. Consequently, the RTV/ANI-co-MAA@MIP-GCE exhibited high specificity, accuracy, and sensitivity for detecting RTV. Density functional theory (DFT) calculations were performed to complement the experimental findings to explore the interactions between the template and monomer, revealing binding energies for RTV–MAA complexes at various template: monomer ratios and elucidating potential intermolecular interactions.</p>https://doi.org/10.21203/rs.3.rs-6910420/v
2D and 3D in vitro photodynamic activities of tetra-substituted symmetric water-soluble cationic zinc(II) phthalocyanines on cancer
No full textIn this study, the PDT activities of 2,9(10),16(17),23(24)-tetrakis(2-dimethylammoniumethoxy) phthalocyaninatozinc(II) tetraiodide (ZnPc1) and 1,8(11),15(18),22(25)-tetrakis(2-trimethylaminoethoxy)phthalocyaninatozinc(II)tetraiodide (ZnPc2) compounds were investigated in 2D monolayer cultures and 3D spheroids of three human cancer cell lines: human submaxillary salivary gland epidermoid carcinoma (A253), human colon colorectal adenocarcinoma (HT29), and human pharynx squamous carcinoma (FaDu) cells. The results indicate that both molecules are non-toxic in the absence of light, which is a crucial feature of an effective photosensitizer. Upon exposure to light, ZnPc1 exhibited significant cytotoxicity in all three cell lines, particularly in FaDu cells, in both 2D monolayer cultures and 3D spheroids, whereas ZnPc2 showed moderate efficacy compared to ZnPc1. PDT using both phthalocyanine (Pc) molecules resulted in substantial reactive oxygen species (ROS) production. Delayed ROS production is higher than that of immediate ROS, indicating their ability to stimulate ROS production over an extended period and retain an oxidative stress response in the cells rather than immediately after PDT. Among these molecules, ZnPc1 induced both immediate and delayed ROS production more efficiently than ZnPc2. Furthermore, singlet oxygen yields of ZnPc1 were higher than ZnPc2, which is consistent with the cytotoxicity results. These findings confirmed that PDT induces an ROS-mediated cytotoxic response. The mechanisms of cellular death triggered by PDT were evaluated, and the results revealed that apoptosis was the predominant process. These findings underscore the potential of ZnPc1 as a potent photosensitizer in PDT while also highlighting the differences between 2D and 3D culture models in evaluating PDT efficacy. While the 2D system enables simplified cytotoxicity evaluation, the 3D spheroid model better replicates physiologically relevant environment and treatment resistance. This comparison underscores necessity of integrating 3D models in PDT studies for more predictive in vivo insights. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1038/s41598-025-09630-7.https://doi.org/10.1038/s41598-025-09630-7http://dx.doi.org/10.1038/s41598-025-09630-
Statistics of Generative Artificial Intelligence and Nongenerative Predictive Analytics Machine Learning in Medicine
No full textThe rapidly evolving landscape of artificial intelligence (AI) and machine learning (ML) in medicine has prompted medical professionals to increasingly familiarize themselves with related topics. This also demands grasping the underlying statistical principles that govern their design, validation, and reproducibility. Uniquely, the practice of pathology and medicine produces vast amount of data that can be exploited by AI/ML. The emergence of generative AI, especially in the area of large language models and multimodal frameworks, represents approaches that are starting to transform medicine. Fundamentally, generative and traditional (eg, nongenerative predictive analytics) ML techniques rely on certain common statistical measures to function. However, unique to generative AI are metrics such as, but not limited to, perplexity and BiLingual Evaluation Understudy score that provide a means to determine the quality of generated samples that are typically unfamiliar to most medical practitioners. In contrast, nongenerative predictive analytics ML often uses more familiar metrics tailored to specific tasks as seen in the typical classification (ie, confusion metrics measures, such as accuracy, sensitivity, F1 score, and receiver operating characteristic area under the curve) or regression studies (ie, root mean square error and R2). To this end, the goal of this review article (as part 4 of our AI review series) is to provide an overview and a comparative measure of statistical measures and methodologies used in both generative AI and traditional (ie, nongenerative predictive analytics) ML fields along with their strengths and known limitations. By understanding their similarities and differences along with their respective applications, we will become better stewards of this transformative space, which ultimately enables us to better address our current and future needs and challenges in a more responsible and scientifically sound manner.https://doi.org/10.1016/j.modpat.2024.100663https://pubmed.ncbi.nlm.nih.gov/3957998
Optimization of Process Parameters for Thick‐Section Composites: A Case Study for Leaf Spring Manufacturing
No full textABSTRACT The present study investigates the optimization of process parameters for the fabrication of thick‐section glass fiber‐reinforced epoxy composites, with a particular focus on glass fiber‐reinforced leaf springs designed for heavy‐duty vehicles. Manufacturing such components presents significant challenges due to low thermal conductivity and the exothermic nature of the curing reaction, which often results in temperature overshoots and potential resin degradation. To address these issues, a combined experimental and computational approach was adopted. Cure kinetics were characterized via Differential Scanning Calorimetry (DSC) and thermal properties by the Hot Disk method. These properties were subsequently integrated into a Finite Element (FE) model to predict curing behavior. A Genetic Algorithm (GA) was employed in two stages: initially for model parameter calibration and subsequently for process parameter optimization. This approach enabled a reduction in overall curing time by up to 50%, while effectively mitigating excessive temperature rise. Furthermore, some practical strategies—such as mold temperature adjustments, enhancement of resin thermal conductivity, and implementation of B‐staging—were proposed to improve process efficiency and product quality. The results demonstrate a process optimization framework for the high‐volume production of thick‐section composite components in automotive applications, achieving an optimal balance between thermal management and manufacturing efficiency.https://doi.org/10.1002/pc.7062
Povscape: imkânsız oyun mekânlarında anamorfik projeksiyonun mekânsal bir oyun mekaniği olarak kullanımına yönelik tasarım yoluyla araştırma yaklaşımı
No full textThesis (M.Sc.) -- Istanbul Technical University, Graduate School, 2025Anamorphosis, an optical illusion in which a distorted image reveals its correct form only when viewed from a specific angle, has historically been used in painting, architecture, and sculpture to manipulate visual perception. This perceptual phenomenon holds untapped potential to be used in digital media, particularly in games. The player is forced to actively restore spatial coherence when perception is rendered functional rather than merely aesthetic, turning seeing into doing. This study investigates anamorphosis, uses anamorphic projection as a technique to create this illusion and adapts this into game design, and practices the projection on environments rather than objects, to transform the player's point of view into a game mechanic that is the key for the progression in spatially fragmented environments. The central research question is: How can anamorphic projection be used to redefine spatial interactions in game environments to challenge the conventional notions of reality and navigation? Simultaneously, the thesis fits into the growing interest in the concept of "impossible spaces," which are environments that logically or visually defy the physical rules of the real world. Inspired by M.C. Escher's recursive structures and visual illusions like the Penrose triangle, recent games that are willing to explore experimental gameplay have been using impossible spaces. These settings challenge conventional ideas of space and continuity by creating a playful contradiction between what appears structurally valid and what is physically possible. While several games experiment with non-Euclidean design and perception-based logic and use anamorphosis, most treat it as a surface-level illusion rather than a systematized mechanic that can serve as the core mechanic of a game. The study uses a Research through Design (RtD) methodology, that emphasizes reflective practice and iterative prototyping as a research tool, producing both knowledge and artifacts. By using this method, the study aims to ground theoretical investigation in practical application. Thanks to this, the mechanic can be evaluated both technically and experientially. To seek the potential of a novel game mechanic that uses anamorphic projection, a generalizable design framework is created. This framework outlines how anamorphic projection can work as a repeatable and modular system in designing puzzles and levels. With connected portal planes and real-time camera capture, the framework makes it possible for fragmented level elements to visually align from a precise angle. When the player navigates and finds the correct viewpoint, the fragmented projected pieces align to form a coherent image and trigger spatial transitions with portals. This system is designed to be flexible, adaptable to a variety of games and levels, and provides a reusable framework for future development. The thesis adopts The Player Experience Inventory (PXI) as an evaluation tool to measure how players react to the mechanic. This validated framework evaluates player experience in two categories: functional consequences (ease of control, progress feedback, audiovisual appeal, goals and rules, challenge) and psychosocial consequences (mastery, curiosity, immersion, autonomy, meaning). The PXI provides a thorough analysis of the suggested mechanic by focusing on both usability and emotional engagement. Based on the general framework, a prototype called POVscape was developed using Unreal Engine 5. The prototype includes three levels, progressing from easier to harder, each designed to test the mechanic in various spatial arrangements. The level designs of the prototype emphasize perspective-dependent interaction. The players experiment with the mechanic and find answers through alignment and movement. Thirty-three people participated in the user testing of the prototype. The research included both quantitative and qualitative methods. Six out of ten PXI constructs that are more relevant for the mechanic were chosen to be scored on a 7-point Likert scale. The participants answered three questions for each construct, as well as three questions for the levels to see how each level affected their view on the constructs. The findings showed that the mechanic was understandable and enjoyable, with all constructs scoring an average point above 5. The qualitative feedback described the mechanic as "mentally engaging" and "intiutive." Even though the prototype served as an introduction to the mechanic and only had three levels, it demonstrated the potential of the framework to create a novel spatial puzzle interaction. This study concludes that anamorphic projection can be used as a reliable spatial game mechanic. The level and puzzle designs could be expanded in future work. The system could be modified for virtual reality (VR), where perception an movement could improve further with the mechanic's features. Ultimately, this thesis offers a conceptual framework and a technical basis for exploring perception as the main interaction method in spatial game mechanic design.M.Sc
A novel silicon photonic integrated circuit for MRI data transmission
No full texthttps://doi.org/10.1109/omn65869.2025.1112598
Search for excited tau leptons in the ττγ final state in proton-proton collisions at = 13 TeV
No full textAbstract Results are presented for a test of the compositeness of the heaviest charged lepton, τ, using data collected by the CMS experiment in proton-proton collisions at a center-of-mass energy of 13 TeV at the CERN LHC. The data were collected in 2016–2018 and correspond to an integrated luminosity of 138 fb −1. This analysis searches for tau lepton pair production in which one of the tau leptons is produced in an excited state and decays to a ground state tau lepton and a photon. The event selection consists of two isolated tau lepton decay candidates and a high-energy photon. The mass of the excited tau lepton is reconstructed using the missing transverse momentum in the event, assuming the momentum of the neutrinos from each tau lepton decay are aligned with the visible decay products. No excess of events above the standard model background prediction is observed. This null result is used to set lower bounds on the excited tau lepton mass. For a compositeness scale Λ equal to the excited tau lepton mass, excited tau leptons with masses below 4700 GeV are excluded at 95% confidence level; for Λ = 10 TeV this exclusion is set at 2800 GeV. This is the first experimental result covering this production and decay process in the excited tau mass range above 175 GeV.https://doi.org/10.1007/jhep06(2025)006https://dx.doi.org/10.5445/ir/1000184867https://dx.doi.org/10.18154/rwth-2025-09953https://dx.doi.org/10.3204/pubdb-2025-03573https://dx.doi.org/10.18154/rwth-2025-09788https://dx.doi.org/10.5445/ir/1000185208http://hdl.handle.net/10261/403127https://doaj.org/article/e368806f1fd44877aea4753428900252http://dx.doi.org/10.13039/501100000781http://dx.doi.org/10.13039/501100000780http://dx.doi.org/10.13039/501100011033http://dx.doi.org/10.13039/100011941https://bib-pubdb1.desy.de/record/635889https://publikationen.bibliothek.kit.edu/1000184867https://doi.org/10.5445/IR/1000184867https://publikationen.bibliothek.kit.edu/1000184867/167170229https://publikationen.bibliothek.kit.edu/1000185208https://doi.org/10.5445/IR/1000185208https://publikationen.bibliothek.kit.edu/1000185208/167170421https://hdl.handle.net/11589/288838https://hdl.handle.net/11384/154956https://link.springer.com/article/10.1007/JHEP06(2025)006https://hdl.handle.net/2158/1439251https://doi.org/10.1007/JHEP06(2025)00