Istinye University

Efficient and robust data clustering remains a challenging task in the field of data analysis. Recent efforts have explored the integration of granular-ball (GB) computing with clustering algorithms to address this challenge, yielding promising results. However, existing methods for generating GBs often rely on single indicators to measure GB quality and employ threshold-based or greedy strategies, potentially leading to GBs that do not accurately capture the underlying data distribution. To address these limitations, this paper leverages the principle of justifiable granularity (POJG) to measure the quality of a GB for clustering tasks and introduces a novel GB generation method, termed GB-POJG. Specifically, a comprehensive black metric integrating the coverage and specificity of a GB is introduced to assess GB quality.} Utilizing this quality metric, GB-POJG incorporates a strategy of maximizing overall quality and an anomaly detection method to determine the generated GBs and identify abnormal GBs, respectively. Compared to previous GB generation methods, GB-POJG maximizes the overall quality of generated GBs while ensuring alignment with the data distribution, thereby enhancing the rationality of the generated GBs. Experimental results obtained from both synthetic and publicly available datasets underscore the effectiveness of GB-POJG, showcasing improvements in clustering accuracy and normalized mutual information. All codes have been released at https://zenodo.org/records/13643332.

MXenes and their composites exhibit remarkable electrical conductivity, mechanical flexibility, and biocompatibility, making them ideal candidates for microrobot fabrication. Their tunable surface chemistry allows for easy functionalization, which enhances their...

Umbilical cord blood (CB)-derived hematopoietic stem and progenitor cells (HSPCs) hold immense potential for regenerative medicine, particularly in hematologic malignancies and immune disorders. CB offers several advantages, including easy collection and reduced risk of graft-versus-host disease compared to other sources, like bone marrow. However, the clinical application of CB is often limited due to the relatively small number of HSPCs present in CB grafts, which can be insufficient for adult patients. This limitation has prompted researchers to explore various methods to expand HSPCs ex vivo. As research continues to refine expansion techniques, the future of CB HSPC therapy appears increasingly promising, offering new hope for patients requiring stem cell transplantation. Approaches to HSPC expansion include the use of cytokines, small molecules, epigenetic modulators, and advanced culture systems that mimic the bone marrow niche as well as emerging techniques such as gene editing. Of the key CB HSPC expansion methodologies, the use of epigenetic modifiers is among the most promising strategies for inducing proliferation while maintaining the stemness of CB HSPC. This section summarizes key methodologies for CB HSPC expansion and their transformative impact on clinical practice while providing a validated protocol for ex vivo expansion of CB-derived HSPCs using valproic acid and/or nicotinamide.

Purpose The purpose of this study was to investigate the morphologic and morphometric features of the pisiform using various anatomical landmarks, and to analyze its topographic relationship with surrounding bony structures. Methods Unilateral CT images of the hand and wrist taken from 208 patients (62 females, 146 males) admitted to Radiology Department of Marmara University Faculty of Medicine between 2014 and 2019 retrospectively analyzed in the study. The mean age of the subjects was 33.4 (range, 14–65) years of age. Eight different measurements were performed using 3D Slicer software and one novel classification was made on the images of 117 (56.25%) right and 91 (43.75%) left hands taken in neutral position. The results were further compared between gender, laterality, and age groups. Results The mean values of the truncated hand length (THL), longitudinal diameter of pisiform (LDP), transverse diameter of pisiform (TDP), and piso-triquetral distance (PTD) were significantly higher for men than for women. No significant difference was found between the right and left side measurements. A significant difference was also observed in PTD values between the age groups. The novel classification used in the present study revealed that the most common shape of triquetral facet of the pisiform was ellipse type (85.6%), followed by round (10.1%), and cylindrical (4.3%) types, respectively. Conclusion The results of the study provide comprehensive morphologic and morphometric data for the pisiform and may lend support for better understanding of the region which would be beneficial for the surgical interventions of the hand and wrist.

Oxide dispersion-strengthened alloys have emerged as a highly effective solution to address the physical, structural, and shielding challenges faced by traditional alloys in nuclear environments. This study presents a comprehensive evaluation of the microstructural, mechanical, and radiation shielding properties of Yb2O3 oxide dispersion-strengthened 316L stainless steel composites at varying Yb2O3 concentrations such as 1%, 5%, 10%, and 20% by weight. XRD analysis revealed lattice distortions, with crystallite sizes decreasing from 11.2267 nm to 9.3351 nm. SEM/EDX analyses confirmed homogeneous Yb2O3 dispersion at lower concentrations, with agglomeration at 20% Yb2O3. The mass attenuation coefficient increased from 56.103 cm²/g to 65.919 cm²/g at 0.015 MeV, marking a 17.5% enhancement. HVL decreased by 40.68% at 0.2 MeV for the 20% Yb2O3 sample. Additionally, the 20% Yb2O3 composite showed nearly 33% lower transmission factor at 3.0 cm thickness and 0.662 MeV. It can be concluded that Yb2O3 reinforcement significantly enhances the microstructural, and gamma-ray attenuation properties of 316L-SS composites, positioning them as promising materials for advanced nuclear shielding and structural applications.

A fundamental feature of Heterogeneous Networks (HetNets) is the increased reuse probability of area-based resources and the enhancement of service quality by enabling small cells to operate within macro cell networks. HetNets have limited resources, and efficient Resource Allocation (RA) schemes must be used to reduce interference, spectrum sharing, and interference among different users. As a result, the significance of resource allocation schemes is increasing. In this study, RA in HetNets, which are systems that meet the demand for high-bandwidth communication, was investigated. The study focused on downlink communication from base stations to users. Orthogonal Frequency Division Multiple Access (OFDMA)-based Discrete Particle Swarm Optimization (DPSO) was used as the method. RA optimization was performed to maximize the communication rates of a particular number of users, the Network Energy Efficiency (NEE), or the Weighted Sum of Energy Efficiency (WSEE) of users. The results were compared with traditional FDMA. The total rate, NEE, and WSEE performance of the results were affected by various parameters such as the number of base stations, the number of users, transmitter power, and static power consumed at base stations. However, the proposed RA method achieved quite good performance for all these parameters. Particularly, as the number of users increases, and resources become limited, the proposed RA method becomes more important. Additionally, this method can be used to ensure equality among users.

Chalcogenides represent a versatile class of materials with diverse properties, enabling their application in a broad range of technologies, including solar cells, LEDs, superconductors, magneto-resistive devices, and topological insulators. In this study, the structural, electronic, optical, phononic, and radiation-related properties of XAl₂S₄ (X = Eu, Fe, Rh) compounds were investigated using first-principles density functional theory (DFT). The electronic properties reveal a semiconducting nature with bandgaps in the range of 1.2–3.4 eV. The computed negative formation energy and phonon calculations confirm phase stability. Analysis of the density of states highlights the specific electronic states contributing to the band structure. The density of states (DOS) analysis for XAl₂S₄ (X = Eu, Fe, Rh) compounds identifies the electronic states contributing to the band structure. The valence band is mainly influenced by S-3p orbitals and X-d states, while the conduction band is predominantly shaped by Al-3p and X-d orbitals. The interaction between X-d and S-3p states plays a significant role in defining the bandgap and electronic transitions. These findings highlight the key contributions of localized and hybridized states in determining the semiconducting nature of these materials, with bandgaps ranging from 1.2 to 3.4 eV. Optically, the reflectivity remains around 30% below 12.0 eV and reaches a maximum of 32% at approximately 13.0 eV. The compounds demonstrate strong potential for radiation shielding, attributed to their high-density elements and effective absorption properties. Notably, the strong optical anisotropy of these materials suggests their potential for polarization-sensitive photodetector applications. The Seebeck coefficient is positive, indicating the properties of a p-type semiconductor with the highest power factor is approximately 2.0 × 1011 W m−1 K−2. At 600 K, the thermoelectric figure of merit ZT reaches its maximum value of 1.2. These findings indicate that XAl₂S₄ compounds are promising candidates for optoelectronic devices and LED technologies, particularly as green phosphors for energy applications. Radiation shielding analysis reveals that the EuAl₂S₄ compound achieves a mass attenuation coefficient of 0.145 cm2/g at 1 MeV, surpassing conventional materials like lead-based shields in low-energy regimes.

In this work, n-type bismuth oxide nanosheets deposited onto n-type silicon substrates by a vacuum evaporation technique under a vacuum pressure of 10⁻⁵ mbar is fabricated to perform as a daylight photodetectors suitable for visible light and infrared communication technology. The n-Si/n-Bi2O3 heterojunction devices exhibited conduction and valence band offsets of 0.89 eV 0.73 eV, respectively. Two Schottky barriers Pt/n-Si and Pt/Bi2O3 of respective barrier heights of 1.65 eV and 0.76 eV are formed on the sides of the heterojunction devices. Dark electrical characterization on the Pt/n-Si/n-Bi2O3/Pt hybrid structure showed a maximum current rectification ratio of 166. The current transport mechanism in the devices was dominated by the Richardson –Schottky thermionic conduction type and by electric field assisted charge carrier tunneling within a barrier of width and height of 60 nm and 0.83 eV, respectively. On the other hand, electrical measurements handled under the illumination of a daylight mini-lamp have shown that the photodetectors under focus exhibit maximum current responsivity, external quantum efficiency percentage, specific detectivity and linear dynamic range of 30 A W⁻¹, 3000%, 1.7 ×1012 Jones and 36.4 dB under illumination power of 82 μW, respectively. The features of the bismuth oxide based photodetectors nominate them for visible and infrared lights illumination technology.

Objective To investigate the efficacy of the cephalosporin/ beta lactamase inhibitor combination ceftazidime-avibactam in hematology patients with hematopoietic stem cell transplantation or receiving chemotherapy alone. Materials and methods In this study, 80 patients who were followed up in the Stem Cell Transplant Center and Hematology Clinic of Istinye University Gaziosmanpaşa Medicalpark Hospital between June 2022 and May 2024 and who received ceftazidime-avibactam treatment for at least 3 days during their hospitalization were evaluated. Demographic characteristics, infectious processes, duration of hospitalization before culture, neutrophil levels and neutropenia duration at the time of treatment initiation, previous antibiotic exposure, Charlson’s Comorbidity index, mechanical ventilation needs and mortality rates were recorded retrospectively. Results Of the patients, 25 (31.25%) were female and 55 (68.75%) were male. The mean age was 50 years (18–86). Thirty-four (42.5%) patients received allogeneic hematopoietic stem cell transplantation and 17 (21.25%) patients received autologous hematopoietic stem cell transplantation. Only 29 (36.25%) patients received chemotherapy. When ceftazidime-avibactam treatment was initiated, 42 (52.5%) patients had a neutrophil count < 0.1 × 10⁹/L. Charlson’s Comorbidity Index was ≥ 3 in 71 (88.75%) patients. Forty-six (57.5%) patients died in the first 28 days after the onset of infection. In multivariate analysis showed that mean age (HR 1.71, CI 1.07–3.05; p = 0.012), pneumonia and need for mechanical ventilation (HR 1.91, CI 1.83–1.98; p = 0.001), clinical improvement status in the first 14 days (HR 1.02, CI 0.97–1.08; p = 0.001) and duration of neutropenia (HR 2.67, CI 2.26–3.08; p = 0.019) were independent risk factors associated with 28-day mortality. Conclusion Mortality due to resistant microorganisms is high in hematologic patients during stem cell transplantation and non-transplant period. Age, pneumonia and need for mechanical ventilation and duration of neutropenia are the most important mortality indicators in hematologic patients. Ceftazidime-avibactam is an effective treatment option in appropriate patients and the clinical response will be better if it can be started before the need for mechanical ventilation develops.

Layered nitrides have diverse compositions and pore profiles with wide applications, and are unique but soft and their characterization is challenging. This paper reviews the layered carbon nitrides' syntheses and applications.

Background In clinical practices, errors in application technique are made while applying topical medications. These errors can result in treatment failure, a reduction in therapeutic response and subpar disease control. The aim of this study was to explore the level of knowledge and attitudes towards application aspects of topical drug preparations amongst patients attending community pharmacies in Alexandria city, Egypt. Methods This descriptive, cross-sectional study evaluated the prevalence of improper use of topical drug preparation amongst the community in Alexandria, Egypt, by participant interviews with a standardized, three-part questionnaire. Results A total of 103 participants with a mean age of 34.9 ± 16.1 years were enrolled in the study. 64% of the respondents reported that they had some knowledge to use a particular type of topical preparation. 50.5% stated that the pharmacist was the main source for the provision of instructions regarding the proper use of topical preparations, followed by the physician (34%). 41.7% of the respondents reported errors that were identified in techniques while using topical preparation. Of those, 90.7% reported a technical application error while using topical preparation. 54.4% reported that they did not use a medication leaflet to get information about proper topical preparation use. Conclusions This study highlights that there are some aspects of application technique errors regarding topical medications encountered by the public. Community pharmacists and other healthcare professionals ought to consider the need for steps to be taken to address patient misunderstandings and avoiding incorrect practices.

Objectives: Transgender individuals continue to face discrimination, particularly in accessing oral healthcare. This study aimed to evaluate dentists' attitudes toward transgender people and their knowledge of gender-affirming care. Materials and Methods: A questionnaire assessing demographic data, clinical approaches, and knowledge of gender-affirming care was distributed via social media, professional chambers, and associations. Descriptive statistics were analyzed using SPSS, with Chi-square and Fisher exact tests, alongside logistic regression for appropriate questions. Results: A total of 403 dentists participated, with 8% reporting professional prejudices against transgender individuals. Dentists who associated transgender patients with increased clinical infection rates were statistically more likely to hold prejudices(p < 0.05). Additionally, 60.2% expressed interest in training to enhance communication with transgender patients. Female dentists were significantly more likely to be open to such training (p < 0.05). Conclusion: The findings highlight a strong desire among dentists for training to improve communication with transgender patients, along with a lack of knowledge about key topics such as gender-affirming, endogenous hormones, and their oral health implications. This underscores the need for targeted educational initiatives in the dental community.

Neighborhood rough sets are an effective model for handling numerical and categorical data entangled with vagueness, imprecision, or uncertainty. However, existing neighborhood rough set models and their feature selection methods treat each sample equally, whereas different types of samples inherently play different roles in constructing neighborhood granules and evaluating the goodness of features. In this study, the sample weight information is first introduced into neighborhood rough sets, and a novel weighted neighborhood rough set model is consequently constructed. Then, considering the lack of sample weight information in practical data, a margin-based weight optimization function is designed, based on which a gradient descent algorithm is provided to adaptively learn sample weights through maximizing sample margins. Finally, an average granule margin measure is put forward for feature selection, and a forward-adding heuristic algorithm is developed to generate an optimal feature subset. The proposed method constructs the weighted neighborhood rough sets using sample weights for the first time and is able to yield compact feature subsets with a large margin. Extensive experiments and statistical analysis on UCI datasets show that the proposed method achieves highly competitive performance in terms of feature reduction rate and classification accuracy when compared with other state-of-the-art methods.

Federated clustering (FC) performs well in independent and identically distributed (IID) scenarios, but it does not perform well in non-IID scenarios. In addition, existing methods lack proof of strict privacy protection. To address the above issues, we propose a new secure federated k -means clustering framework to achieve better clustering results under privacy requirements. Specifically, for the clients, we use cluster centers (representative points) generated by k -means to represent the corresponding clusters. These representative points can effectively preserve the structure of the local data and they are encrypted by differential privacy. For the server, we propose two methods to reprocess the uploaded encrypted representative points to obtain better final cluster centers, one uses k -means, and the other considers the improved density peaks (density cores) as final centers and then sends them back to the clients. Finally, each client assigns local data to their nearest centers. Experimental results show that the proposed methods perform better than several centralized (nonfederated) classical clustering algorithms [ k -means, density-based spatial clustering of applications with noise (DBSCAN), and density peak clustering (DPC)] and state-of-the-art (SOTA) centralized clustering algorithms in most cases. In particular, the proposed algorithms perform better than the SOTA FC framework k -FED (ICML2021) and MUFC (ICLR2023).

Purpose Endoscopic transorbital skull base approaches are always challenging and require good anatomical knowledge.The aim of this study was to describe the anatomical pathways of endoscopic transorbital approaches and to determine the limitations of these procedures. To evaluate the feasibility of the tubular retractor and the difference with manual retractor. Methods The targets of endoscopic transorbital approach were the anterior and middle cranial fossa, mesial temporal region, meckel’s cave, petroclival area, opticocarotid region, anterior and lateral walls of the cavernous sinus, etc. Step-by-step anatomical dissections were performed in cadaveric heads using manual and tubular retractors. Results Anterior and middle cranial fossa was reached. The branches of the trigeminal nerve, the lateral wall of the cavernous sinus, meckel’s cave and gasserian ganglion were exposed by manual and tubular retraction using an endoscopic transorbital approach. Access to the temporal horn of the lateral ventricle and the mesial temporal region was more accessible with a tubular retractor. Also, following the anterior clinoidectomy, the cavernous segment of the internal carotid artery, as well as, the arteries of the anterior circulation were exposed to gain access the vascular skull base lesions. Conclusion The endoscopic transorbital approach is suitable for the surgical treatment of many pathologies located in the anterior and middle skull base. It provides direct access to vascular and tumoral lesions. We observed that mesial temporal region interventions are possible with this approach. The transtubular technique may have some limitations, but in selected cases it can provide clear vision without brain retraction.

It is widely acknowledged that the gut microbiome plays a crucial role in both human and animal health. Nutrition, genetic predisposition, environmental factors, and epigenetic alterations significantly influence the microbiome and its interactions with the host. Epigenetic modifications include DNA methylation, histone modification and regulation of non-coding RNAs. Given the ability of reptiles to survive, thrive and adapt over millions of years, it is logical to be associated with their robust immune system and unique gut microbiome/epigenetic alterations, and it is a worthy area of investigation. As up to 80% of the immune system resides in the gut, the reptilian gut microbiome represents a unique potential resource for discovery of novel molecules that impact the host epigenome. Herein, we discuss the role of epigenetics and the gut microbiome, with a focus on long-lived reptiles such as crocodiles. Finally, epigenetic gut microbial modulation strategies are deliberated upon.

Uncrewed Aerial Vehicles (UAVs) are frequently utilized in several domains such as transportation, distribution, monitoring, and aviation. A significant security vulnerability is the Global Positioning System (GPS) Spoofing attack, wherein the assailant deceives the GPS receiver by transmitting counterfeit signals, thereby gaining control of the UAV. This can result in the UAV being captured or, in certain instances, destroyed. Numerous strategies have been presented to identify counterfeit GPS signals. Although there have been notable advancements in machine learning (ML) for detecting GPS spoofing attacks, there are still challenges and limitations in the current state-of-the-art research. These include imbalanced datasets, sub-optimal feature selection, and the accuracy of attack detection in resource-constrained environments. The proposed framework investigates the optimal pairing of feature selection (FS) methodologies and deep learning techniques for detecting GPS spoofing attacks on UAVs. The primary objective of this study is to address the challenges associated with detecting GPS spoofing attempts in UAVs. The study focuses on tackling the issue of imbalanced datasets by implementing rigorous oversampling techniques. To do this, a comprehensive approach is proposed that combines advanced feature selection techniques with powerful neural network (NN) architectures. The selected attributes from this process are then transmitted to the succeeding tiers of a hybrid NN, which integrates convolutional neural network (CNN) and bidirectional long short-term memory (BiLSTM) components. The Analysis of Variance (ANOVA) + CNN-BiLSTM hybrid model demonstrates superior performance, producing exceptional results with a precision of 98.84%, accuracy of 99.25%, F1 score of 99.26%, and recall of 99.69%. The proposed hybrid model for detecting GPS spoofing attacks exhibits significant improvements in terms of prediction accuracy, true positive and false positive rates, as well as F1 score and recall values.