167 results
Search Results
Now showing 1 - 10 of 167
Article Citation - WoS: 12Citation - Scopus: 14The Markov Discrete Time Δ-Shock Reliability Model and a Waiting Time Problem(Wiley, 2022) Chadjiconstantinidis, Stathis; Eryilmaz, Serkandelta-shock model is one of the widely studied shock models in reliability theory and applied probability. In this model, the system fails due to the arrivals of two consecutive shocks which are too close to each other. That is, the system breaks down when the time between two successive shocks falls below a fixed threshold delta. In the literature, the delta-shock model has been mostly studied by assuming that the time between shocks have continuous distribution. In the present paper, the discrete time version of the model is considered. In particular, a proper waiting time random variable is defined based on a sequence of two-state Markov dependent binary trials and the problem of finding the distribution of the system's lifetime is linked with the distribution of the waiting time random variable, and we study the joint as well as the marginal distributions of the lifetime, the number of shocks and the number of failures associated with these binary trials.Article Citation - WoS: 2Citation - Scopus: 2Potential Role of SGLT-2 Inhibitors in Improving Allograft Function and Reducing Rejection in Kidney Transplantation(Wiley, 2025) Demir, Mehmet Emin; Helvaci, Ozant; Yildirim, Tolga; Merhametsiz, Ozgur; Sezer, SirenSodium-glucose cotransporter-2 inhibitors (SGLT-2i) have demonstrated renoprotective and cardioprotective benefits beyond their antiglycemic effects. Their potential utility in kidney transplant recipients (KTRs) for preserving graft function and reducing rejection risk is currently under active investigation. Preliminary studies indicate that SGLT-2i therapy stabilizes estimated glomerular filtration rate (eGFR), decreases glomerular hyperfiltration, and improves metabolic outcomes in KTRs. Emerging clinical evidence also suggests that SGLT-2i may be associated with reduced rates of acute rejection, although direct immunosuppressive actions remain unclear. Experimental findings further suggest that SGLT-2i modulates gene regulation pathways involved in inflammation, oxidative stress, and fibrosis, contributing to improved allograft outcomes. Current safety data in KTRs are reassuring, without significant increases in urinary tract infections or adverse graft events. Nevertheless, long-term prospective studies specific to transplant populations are lacking. This review summarizes available evidence regarding the mechanisms of action, clinical efficacy, and safety profile of SGLT-2i in kidney transplantation, emphasizing their metabolic, hemodynamic, inflammatory, and immunomodulatory effects.Article Citation - WoS: 26Citation - Scopus: 28Reliability Assessment for Discrete Time Shock Models Via Phase-Type Distributions(Wiley, 2021) Eryilmaz, Serkan; Kan, CihangirIn this paper, particular shock models are studied for the case when the times between successive shocks and the magnitudes of shocks have discrete phase-type distributions. The well-known shock models such as delta shock model, extreme shock model, and the mixed shock model which is obtained by combining delta and extreme shock models are considered. The probability generating function and recursive equation for the distribution of the system's lifetime are obtained for the cases when the interarrival times between shocks and the magnitudes of shocks are independent and when they are dependent. System reliability is computed for particular interarrival distributions such as geometric, negative Binomial and generalized geometric distributions.Article Comparative Assessment and Performance Analysis of Interference Mitigation Techniques for Co-Existent Non-Geostationary and Geostationary Satellites(Wiley, 2024) Ozturk, Faik; Aydin, Elif; Kara, AliIn recent years, technological developments with user demands, reduced production, and launch costs have rapidly increased the number of Low Earth Orbit (LEO) satellites in space. Since LEO satellites use the same frequency band as existing Geostationary Earth Orbit (GEO) satellites, the interference coordination between the two satellite networks is vital. In order to minimize the co-existent interference between these satellite networks, studies perform on different interference mitigation strategies. In this paper, analysis and comparative assessment of these interference mitigation techniques are presented for the co-existent Non-Geostationary Earth (NGEO) and GEO systems. More specifically, power control (PC) and spatial isolation-based link adaptation (SILA) techniques are studied comparatively for the performance evaluation. It is shown that the communication link bandwidth is more efficiently utilized in the SILA technique when compared with the PC technique. Moreover, the multi-objective optimization problem (MOP) approach in the SILA technique is demonstrated to be more effective when compared with the single-objective optimization problem (SOP) approach used in the PC technique as the simultaneous prioritizing objective functions outperforms single prioritization. Finally, it is shown that when the PC technique is applied together with the SILA technique, the exclusive angle (EA) can be reduced up to 8% for 100 Mbps, and 8.5% for 200 Mbps transmission bit rates in different operational scenarios. The presented performance evaluation in this paper may help the satellite operator or decision-maker gain insights on which mitigation technique can be used in the case of a co-existent interference. This paper proposes analysis and comparative assessment of interference mitigation techniques for the co-existent Non-Geostationary Earth (NGEO) and Geostationary Earth Orbit (GEO) systems. Spatial isolation-based link adaptation (SILA) and power control (PC) techniques are studied comparatively for the performance evaluation. The obtained optimization results show that the communication link bandwidth is more efficiently utilized in the SILA technique when compared with the PC technique because of the simultaneous prioritizing of objective functions. imageArticle Citation - WoS: 42Citation - Scopus: 47Color-Emotion Associations in Interiors(Wiley, 2020) Gunes, Elif; Olgunturk, NilgunEmotional reactions to red, green, blue, and gray colors in a living room were investigated using a self-report measure. Participants first watched a short video of a 3D model of a living room. Next, they were asked to match the living rooms with facial expressions of six basic emotions. The most stated emotions associated for the red room were disgust and happiness, while the least stated emotions were sadness, fear, anger, and surprise; for the green room, neutral and happiness were the most stated emotions, and anger, surprise, fear, and sadness were the least stated ones; for the blue room, neutral was the most stated emotion, while the least stated emotions were anger and surprise. Neutral, disgust, and sadness were the most stated emotions for the gray room. Gender differences were not found in human emotional reactions to living rooms with different wall colors.Article Citation - WoS: 11Citation - Scopus: 13Sustainable Human Resource Management and Job Satisfaction-Unlocking the Power of Organizational Identification: a Cross-Cultural Perspective From 54 Countries(Wiley, 2024) Wojtczuk-Turek, Agnieszka; Turek, Dariusz; Edgar, Fiona; Klein, Howard J.; Bosak, Janine; Okay-Somerville, Belgin; Karamustafa-Kose, GueldemSustainable human resource management is gaining importance in organizations due to its role in developing a sustainable work environment and well-being. This paper discusses the relationship between employee perceptions of sustainable human resource management and job satisfaction in 54 countries. We propose that sustainable HRM is positively associated with job satisfaction but that this relationship is moderated by employees' identification with the organization and country-level individualism-collectivism. Thus, we suggest national culture functions as a second-level moderator of the relationship of sustainable HRM with organizational identification on job satisfaction. Findings from the multi-level analyses using data from 14,502 employees nested within 54 countries provided support for our hypotheses, namely that employee perceptions of sustainable HRM were positively associated with job satisfaction and that this relationship was more pronounced for employees with lower levels compared to higher levels of organizational identification in individualistic rather than collectivistic countries. These findings bear important implications for both theory and practice.Review Citation - WoS: 1Citation - Scopus: 1Software Maintenance Practices Using Agile Methods Towards Cloud Environment: a Systematic Mapping(Wiley, 2024) Almashhadani, Mohammed; Mishra, Alok; Yazici, AliAgile methods have emerged to overcome the obstacles of structured methodologies, such as the waterfall, prototype, spiral, and so on. There are studies showing the usefulness of agile approaches in software development. However, studies on Agile maintenance are very limited in number. Regardless of the chosen methodology, software maintenance can be carried out in either a local (on-the-premise) or global (distributed) environment. In a local environment, the software maintenance team is co-located on the same premises, while in a global environment, the team is geographically dispersed from the customer. The main objective of this Systematic Mapping (SM) study is to identify the practices useful for software maintenance using the Agile approaches in the Cloud environment. We have conducted a comprehensive search in well-known digital databases and examined the articles that map to the pre-defined inclusion criteria. The study selected and analyzed 48 articles out of 320 published between 2000 and 2022. The findings of the mapping study reveal that Agile can resolve the major issues faced in traditional software maintenance, making the role of this approach significant in global/distributed software maintenance. Cloud computing plays a vital role in software maintenance. Most of the studies highlight the application of XP- and Scrum-based Agile maintenance models. The study found a need for more Agile maintenance solutions in the cloud, highlighting the importance of agile in software maintenance, both locally and globally. Irrespective of the environment, Cloud computing provides a centralized platform for collaboration and communication, while also offering scalability and flexibility to adapt to diverse infrastructure needs. This allows agile maintenance practices to be implemented across both local and global environments, leveraging the cloud's capabilities to overcome geographical and infrastructural challenges. imageArticle Citation - WoS: 6Citation - Scopus: 9Development and Performance Analysis of Polybenzimidazole/Boron Nitride Composite Membranes for High-Temperature Pem Fuel Cells(Wiley, 2022) Hussin, Dedar Emad; Budak, Yagmur; Devrim, YilserIn this research, polybenzimidazole/boron nitride (PBI/BN) based composite membranes have been prepared for high-temperature PEM fuel cell (HT-PEMFC). BN was preferred because of its superior thermal robustness, high chemical stability, non-conductor property, and high plasticizer characteristic. The loading of BN in the composite membrane was studied between 2.5 to 10 wt%. The composite membranes were characterized using TGA, DSC, XRD, SEM, mechanical tests, acid doping/leaching, and proton conductivity measurements. The highest conductivity of 0.260 S/cm was found for PBI/BN-2.5 membrane at 180 degrees C. It has been determined that the PBI/BN-2.5 membrane has higher performance than the PBI membrane according to the HT-PEMFC tests performed with Hydrogen and dry air. The heightened HT-PEMFC performance can be ascribed to interactive effects between BN particles and the PBI polymer matrix. PBI/BN composite membranes show a good perspective in the high-temperature PEMFC applications.Article Citation - WoS: 4Citation - Scopus: 4The Role of Temperament and Parenting on Anxiety Problems Among Toddlers: Moderating Role of Parenting and Mediating Role of Attachment(Wiley, 2022) Bahtiyar-Saygan, Bahar; Berument, Sibel KazakAnxiety problems are seen as early as 1-2 years of age. Among others, parenting and child temperament are considered as the most important factors affecting anxiety in early childhood. In the current study, the unique roles of parenting (maternal overprotectiveness and warmth) and temperament (behavioral inhibition and negative emotionality), parenting-temperament interactions, and mediating role of ambivalent attachment between behavioral inhibition and anxiety were investigated. One-hundred mother-child (18-36-month-old) dyads participated in this study. Children's anxiety and temperament were measured through mother-reported scales, attachment was measured by observation via home visits, and parenting dimensions were measured via both mother-reported scales and observation. The results revealed that behavioral inhibition and overprotectiveness were positively associated with toddlers' anxiety, whereas there were no significant direct associations of negative emotionality and warmth with anxiety. However, the interaction between behavioral inhibition and warmth predicted toddler's anxiety; that is, if behaviorally inhibited children had mothers who were low on warmth, those children were more likely to exhibit anxiety symptoms compared to children with low behavioral inhibition, whereas anxiety levels did not change for children of warm mothers. Ambivalent attachment mediated the relationship between behavioral inhibition and anxiety. The nature of parent-child interactions is discussed based on toddlerhood anxiety.Article Citation - WoS: 40Citation - Scopus: 44Surface Characterization and Radical Decay Studies of Oxygen Plasma-Treated Pmma Films(Wiley, 2013) Ozgen, Ozge; Aksoy, Eda Ayse; Hasirci, Vasif; Hasirci, NesrinPolymethylmethacrylate (PMMA) films were modified by RF oxygen plasma with various powers applied for different periods, and the effects of these parameters on the surface properties such as hydrophilicity, surface free energy (SFE), chemistry, and topography were investigated by water contact angle, goniometer, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy, and the types of the created free radicals and their decay were detected by electron spin resonance spectroscopy (ESR). SFE and contact angle results varied depending on the plasma parameters. Oxygen plasma treatment (100 W-30 min) enhanced the hydrophilicity of PMMA surface as shown by decreasing the water contact angle from 70 degrees to 26 degrees. XPS analysis showed the change in the amounts of the present functionalities as well as formation of new groups as free carbonyl and carbonate groups. The roughness of the surface increased considerably from similar to 2 nm to similar to 75 nm after 100 W-30 min oxygen plasma treatment. ESR analysis indicated the introduction of peroxy radicals by oxygen plasma treatment, and the intensity of the radicals increased with increasing the applied power. Significant decrease in radical concentration was observed especially for the samples treated with higher powers when the samples were kept under the atmospheric conditions. As a conclusion, RF plasma, causes changes in the chemical and physical properties of the materials depending on the applied parameters, and can be used for the creation of specific groups or radicals to link or immobilize active molecules onto the surface of a material. Copyright (C) 2012 John Wiley & Sons, Ltd.
