Recep Tayyip Erdoğan Üniversitesi Kurumsal Akademik Arşivi
DSpace@RTEÜ, Recep Tayyip Erdoğan Üniversitesi tarafından doğrudan ve dolaylı olarak yayınlanan; kitap, makale, tez, bildiri, rapor, araştırma verisi gibi tüm akademik kaynakları uluslararası standartlarda dijital ortamda depolar, Üniversitenin akademik performansını izlemeye aracılık eder, kaynakları uzun süreli saklar ve yayınların etkisini artırmak için telif haklarına uygun olarak Açık Erişime sunar.
Güncel Gönderiler
The effect of değirmendere on hydrography and nutrient salt distribution in the southeastern Black Sea (Trabzon) coastal waters
(Istanbul University Faculty of Aquatic Sciences, 2026) Fidan, Dilek; Ağırbaş, Ertuğrul; Kalıpçı, Ömer; Yavuz, Meryem; Altınbaş, Mehmet; Örnek, Volkan; Aydın, Ayşe Nur
In this study, the physical properties and nutrient salt composition of coastal waters affected by Değirmendere along the Trabzon coast of the Southeastern Black Sea were compared with stations representing open sea conditions relatively independent of river influence. Fieldwork was planned for March and August 2025 to capture two contrasting hydrographic conditions; sampling was carried out at depths of 0–200 m along the river-influenced TM (Trabzon-Center; TM1–TM4) line and the reference TY (Trabzon-Yomra; TY1–TY4) line. Temperature, salinity, and density profiles of the water column were obtained using CTD; dissolved inorganic nitrogen species (nitrate, nitrite, ammonium), orthophosphate, reactive silicate, and total nitrogen and total phosphorus concentrations were measured using an auto-analyzer and statistically evaluated using the Month×Line approach. In March, a cold and vertically well-mixed water column of 9 °C was observed in both channels, while in August, a warmer and less dense layer developed at the surface and a distinct thermocline/pycnocline formed between 20 and 40 m. While no significant difference was observed between TM and TY in terms of salinity and density, nutrient salts showed a significant change from the coast to the open sea and from the surface to the depths. Near the coast, TM showed a higher tendency for ammonium and total nitrogen, while total phosphorus and silicate were relatively higher in TY in most cases. The effects of month, line, and interaction were pronounced on total nitrogen, with enrichment being more prominent in TY in March and in TM in August. DIN:PO43-ratios above the Redfield ratio generally indicate phosphorus limitation; although Değirmendere increases enrichment near the coast, this effect weakens within a few nautical miles, indicating that the trophic status of the region remains relatively balanced in terms of eutrophication. This study provides a local reference dataset that comparatively documents river effects during two distinct periods rather than representing an annual cycle.
Matrix domain of the second-order q-Cesàro matrix in classical sequence spaces
(American Institute of Mathematical Sciences, 2026) Ellidokuzoğlu, Hacer Bilgin; Demiriz, Serkan
In this paper, we study a second-order q-Cesàro matrix and its matrix domains in the spaces c0 and c. We establish basic structural results, including inclusion relations, connections with earlier Cesàro-type sequence spaces, the duals of these spaces, and the associated matrix transformations. Our approach extends known work on q-Cesàro operators and provides a starting point for further investigations of higher-order q-averaging methods in summability theory.
Subclinical corneal endothelial alterations in Familial Mediterranean Fever patients during clinical remission
(Springer, 2026) Sümer, Fatma; Cüre, Osman; Kızılkaya, Bayram; Subaşı, Sevgi
Purpose: Although ocular involvement in Familial Mediterranean Fever (FMF) has been described, the corneal endothelium has not been systematically evaluated in these patients. This study aimed to compare corneal endothelial and anterior segment parameters between FMF patients in clinical remission and healthy controls, and to explore whether these parameters differ according to MEFV M694V genotype. Methods: In this prospective, observational case–control study, 90 genetically confirmed FMF patients in clinical remission and 60 age- and sex-matched healthy controls were evaluated. Only the right eye of each participant was analyzed. Corneal endothelial parameters were assessed by non-contact specular microscopy, and corneal structural parameters by Scheimpflug-based tomography. Measured parameters included endothelial cell density (ECD), central corneal thickness (CCT), coefficient of variation of cell area (CV), and percentage of hexagonal cells (HEX). MEFV mutation analysis was performed by Sanger sequencing. Results: Compared with controls, FMF patients showed a lower ECD (median 2154.5 vs. 2348 cells/mm2, p < 0.001; approximately 8.2% lower), a higher CCT (556.5 vs. 543 μm, p < 0.001), a higher CV (42 vs. 39.5, p = 0.003), and a lower HEX (44.5% vs. 48%, p < 0.001). Intraocular pressure was modestly higher (18 vs. 15 mmHg, p < 0.001) and the iridocorneal angle was narrower (42° vs. 47°, p < 0.001) in the FMF group, with both groups remaining within normal physiological ranges. Within the FMF group, patients homozygous for M694V (n = 14) showed a higher mean CCT (540.93 ± 39.14 vs. 510.93 ± 36.21 μm, p = 0.020) and a lower median ECD (2071 vs. 2218.5 cells/mm2, p = 0.006) than heterozygotes (n = 29). In an exploratory multivariable logistic regression within this subgroup, CCT and ECD were jointly associated with M694V homozygous versus heterozygous status (correct classification 69.8%). Conclusion: FMF patients in clinical remission show measurable differences in corneal endothelial parameters compared with healthy controls, and these differences appear more pronounced in M694V homozygous patients. Because the study is cross-sectional, it is not possible to conclude that these parameters reflect ongoing disease activity; prospective, longitudinal studies are needed to determine whether corneal endothelial assessment has a role in the ophthalmologic follow-up of patients with FMF.
Multiyear evaluation of agronomic traits, nutritional quality, macro and microelement profiles of white maize genotypes (Zea mays L.) under Black Sea conditions
(Frontiers Media SA, 2026) Özata, Erkan; Alaca, Barış; Yıldırım, Gözde Hafize; Aboud, Nora M. Al; Altaf, Muhammad Tanveer
White maize (Zea mays L.) is increasingly valued for diversified food uses, yet agronomic performance and nutritional quality can fluctuate markedly across humid temperate seasons. This study evaluated 14 white maize testcross genotypes, including the commercial check P2948W, across five consecutive field seasons (2020-2024) in the Black Sea Region of Türkiye. Phenology and plant architecture, grain yield (t ha-1), major compositional traits (protein, oil, starch, cellulose and ash), and macro- and microelement concentrations (Ca, Mg, K, P, Fe, Zn, Cu and Mn) were assessed using near-infrared spectroscopy (NIRS) and standard field protocols. Data were analyzed using linear mixed-effects models to partition genotype, year, and genotype x year effects, followed by multivariate visualization (genotype x trait, GT, biplot) and stability assessment using AMMI and GGE biplot approaches (with years treated as environments). Grain yield showed wide genotypic variation (7.23-11.43 t ha-1), with P2948W ranking highest and TTBYM2019–37 lowest on the across-year mean basis, whereas pollen shedding occurred within a narrower window (73.7-78.1 days after planting). In contrast, most compositional traits and mineral means exhibited limited genotypic separation in the combined analysis, indicating strong seasonal influence on quality and mineral expression. Overall, the combined mixed-model and stability framework supports evidence-based selection of high-biomass, broadly adapted white maize candidates for regional cultivar development and provides a transparent basis for multi-year evaluation of quality and mineral attributes.
Plasma PDGFRβ and PSD4 methylation levels for non-invasive staging of liver fibrosis
(Kare Publishing, 2026) Ulukan, Burge; Yang, Hong; Uludag, Hande; Zhang, Cheng; Eren, Fatih; Yılmaz, Yusuf; Zeybel, Mujdat
Background and Aim: While liver biopsy remains the reference standard for assessing hepatic fibrosis, the major prognostic factor in metabolic dysfunction-associated steatotic liver disease (MASLD), its inherent limitations have driven the search for innovative non-invasive diagnostic tests. In this study, we sought to evaluate the diagnostic accuracy of plasma PDGFRβ and PSD4 methylation levels, integrated within machine learning algorithms, for non-invasive staging of hepatic fibrosis in patients with MASLD, and to compare its performance against established non-invasive biomarkers. Materials and Methods: Patients with biopsy-proven MASLD and healthy controls were recruited from the three institutions. Quantitative methylation of circulating cell-free DNA was assessed using bisulfite modification and pyrosequencing. The resulting data were used to develop linear discriminant analysis, random forest, and support vector machine algorithms to identify patients at different stages of fibrosis. Results: The study included 234 patients with histologically confirmed MASLD and 43 healthy controls. Each dataset was validated using an independent cohort. Advanced fibrosis was associated with elevated plasma PDGFRβ and PSD4 methylation levels in both the discovery and validation cohorts. The integration of plasma DNA methylation markers with clinical parameters demonstrated performance comparable to that of existing noninvasive biomarkers for detecting both significant and advanced fibrosis, achieving area under the curve scores exceeding 0.75 across all models. Conclusion: Supervised machine learning algorithms incorporating plasma PDGFRβ and PSD4 DNA methylation levels show promise as a non-invasive approach for assessing hepatic fibrosis in MASLD.
