İstanbul Sağlık ve Teknoloji Üniversitesi Kurumsal Akademik Arşivi
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Güncel Gönderiler
A comprehensive evaluation of the relationships between craniofacial features, oral behaviors, respiratory pattern, sleep, and posture in adolescents
(İstanbul Sağlık ve Teknoloji Üniversitesi, Lisansüstü Eğitim Enstitüsü, 2026) Yıldız, Saliha Yağmur
This study was conducted to comprehensively evaluate the relationships between craniofacial features, oral behaviors, respiratory pattern, sleep and posture in adolescents aged 12–17 years. A total of 180 adolescents in the permanent dentition stage with orthodontic treatment needs were included in the study. Clinical assessments included occlusion, orofacial structures, and upper airway-related findings. Parafunctional habits were evaluated using the Oral Behaviors Checklist. Respiratory capacity was assessed by Peak Nasal Inspiratory Flow (PNIF) and oxygen saturation (SpO₂) measurements. Sleep quality was evaluated using the Children's Sleep Habits Questionnaire (CSHQ) and posture was assessed with the New York Posture Scale (NYPS). Statistical significance was set at p<0.05. Individuals with a tendency toward mouth breathing exhibited significantly lower nasal airflow, reduced oxygen saturation, and higher sleep-related symptom scores (all p<0.001). Additionally, significant differences were identified among malocclusion classes in terms of oral behaviors, respiratory parameters, oxygenation changes, sleep findings, and posture (p<0.05). Multivariable analyses revealed that mouth-breathing tendency was independently associated with increased oral behaviors, lower PNIF and SpO₂ values, and higher CSHQ total scores. Among the malocclusion classes, the Class III group was found to be associated with an increased number of oral behaviors and lower PNIF values in some models. The findings indicate that there are significant interrelated associations among malocclusion, parafunctional habits, respiratory parameters, sleep, and posture, particularly in relation to mouth-breathing tendency. These results support the importance of evaluating airway, sleep, oral behaviors, and posture together in clinical assessments.
CFD analysis of counterflow channel type heat exchangers
(Liberty Publishing House, 2026) Şimşek Uzun, Sevda; Tanrıver, Kürşat; Aydın, Diyar Can; Koçyiğit, Ümit Muhammet; Romanello Bueno, Jose Geraldo
Heat exchangers are important engineering systems. They have a key role in energy recovery and improving process efficiency. Counter-flow heat exchangers give better heat transfer because they keep a higher temperature difference between the two fluids. However, there are still only a few studies that examine the effects of inlet temperatures and flow velocities together. This makes it difficult to find the best operating conditions and improve the design. In this study, the thermal performance of a counter-flow channel heat exchanger was studied by using Computational Fluid Dynamics (CFD). The main aim of this study is to examine the hot fluid velocity, cold fluid velocity, and inlet temperature difference together. The effects of these three parameters on heat transfer performance were compared in one parametric study. A three-dimensional model was created in ANSYS Fluent. All simulations were carried out under laminar flow conditions. Different operating cases were compared to determine the main factors affecting the hot fluid outlet temperature. The results showed that when the hot fluid inlet velocity increased from 0.07 m/s to 9.6 m/s, the hot fluid outlet temperature increased from 283.18 K to 326.58 K. The cold fluid outlet temperature also increased from 277.43 K to 283.17 K. On the other hand, increasing the cold fluid velocity decreased the outlet temperatures of both fluids. In addition, when the inlet temperature difference increased from 65 K to 90 K, the hot fluid outlet temperature increased from 310.56 K to 323.55 K, and the cold fluid outlet temperature increased from 281.32 K to 283.45 K. The temperature distribution also changed along the channel. This shows that these parameters have an important effect on heat transfer. The results show that the inlet conditions are very important for the thermal performance of counter flow heat exchangers. This study also shows that CFD is a useful and reliable tool for heat exchanger design. In the future, this work can be improved by using different geometries, turbulence models, and optimization methods.
Air ticket sales forecasting for B2B travel agencies
(Emerald Publishing, 2026) Uzun-Per, Meryem; Akkaya, Ümit Murat; Kalkan, Habil
Purpose – This study addresses the air ticket sales forecasting problem for business-to-business (B2B) travel agencies, a largely unexplored area compared to airlines and business-to-consumer agencies. To meet guarantee deposit requirements and manage financial risk exposure, B2B agencies require accurate demand estimation for budget planning and revenue management. The study proposes a hybrid deep learning forecasting model integrating recurrent neural network (RNN), long short-time memory (LSTM) and bidirectional long short-term memory (BiLSTM) architectures to capture both short-term fluctuations and long-term temporal dependencies in ticket sales data. Design/methodology/approach – Approximately eight years (from 3 August 2014 to 2 June 2022) of daily search and ticket sales data from a B2B travel consolidator agency were combined with external variables, including holidays, weather conditions, exchange rates, gross domestic product per capita and COVID-19 cases. Two datasets (with and without pandemic data) were constructed. After preprocessing and Random Forest feature selection, seasonal autoregressive integrated moving average (SARIMA), Prophet, RNN, LSTM and BiLSTM models were implemented and compared with the proposed hybrid architecture using a sliding window forecasting framework. Performance was evaluated using mean absolute percentage error (MAPE) and root mean squared error (RMSE). Findings – The proposed hybrid model achieved the highest forecasting accuracy across both datasets, outperforming statistical and individual deep learning models. It obtained MAPE values of 5.83% and 6.16% and RMSE values of 0.0379 and 0.0411, respectively. BiLSTM ranked as the second-best method, while SARIMA and Prophet showed substantially lower accuracy. Results also indicated that excluding pandemic variables did not significantly reduce predictive performance, but still, pandemic-related volatility increased the error rate of most of the methods and increased forecasting difficulty. Originality/value – This research is the first to examine ticket sales forecasting specifically for B2B travel agencies. It introduces a novel hybrid sequential deep learning architecture and evaluates the role of pandemic and macroeconomic variables in forecasting performance. The findings demonstrate the effectiveness of hybrid recurrent models for complex real-world demand forecasting problems.
Editorial for special issue of deep brain stimulation
(Elsevier, 2026) İşler, Cihan; Değirmenci, Yıldız; Kocabıçak, Ersoy
Dear Colleagues, We are pleased to present the special issue consisting of selected topics that were presented at the fifth Clinical Neuroscience Course held in Atlas University, between 8 and 11 December, 2022. The course was organized by the national Deep Brain Stimulation Society of Turkiye, which is a chapter of the Deep Brain Stimulation Society.
Professional grief and the second victim experience in neurosurgery: An international cross-sectional study on professional sustainability and educational implications
(Elsevier, 2026) Şanlıer, Nafiye; Flora Göy, Defne; Sulaimanov, Umid; Moniri, Ariorad; Akbaş, İbrahim Halil; Ismayilova, Gular; Demir, Hüseyin; Öztürk, Öykü; Nizzola, Mariagrazia; Hatipoğlu Majernik, Gökçe
OBJECTIVE Adverse events are inevitable in neurosurgical practice and may have significant emotional and professional implications for surgeons. While second victim experiences have been increasingly recognized, the role of professional grief remains insufficiently characterized within the field of neurosurgery. This study aimed to examine professional grief as a component of the second victim experience and its associations with distress, support dimensions, educational needs, and professional sustainability. METHODS We conducted an international, cross-sectional, anonymous web-based survey among neurosurgeons and neurosurgical trainees. Professional grief related to a personally impactful adverse event was assessed retrospectively using the Professional Bereavement Scale-Short-term Bereavement Reactions Subscale (PBS-Acute); scores therefore reflect retrospectively recalled acute grief responses rather than contemporaneously measured reactions. Second victim dimensions were evaluated with the Second Victim Experience and Support Tool-Revised (SVEST–R). Associations among grief severity, second victim dimensions, and professional sustainability indicators were analyzed using correlation and multivariable regression. RESULTS Of 465 respondents from 49 countries, 314 completed the survey and were included in the analysis. A total of 240 participants (76.4%) reported a personally impactful adverse event. Professional grief severity was substantial among respondents (PBS-Acute mean 37.9 ± 13.8) and was strongly correlated with psychological distress (ρ = 0.71, p < 0.001). Higher grief severity was independently associated with increased turnover intention (β = 0.026, p < 0.001). Perceived preventability and primary surgeon role were associated with higher grief severity, while event timing and seniority were not. Supervisor support was inversely associated with grief severity. Participants reported substantial unmet educational needs related to medicolegal processes, communication with patient families, and grief coping skills. CONCLUSIONS Among surveyed neurosurgeons who described a personally impactful adverse event, professional grief was frequently reported. Professional grief in this sample was associated with second victim experiences, psychological distress, and indicators of professional vulnerability. These cross-sectional associations suggest that professional grief may warrant consideration in structured educational models and tiered support systems within neurosurgical training and institutional practice. Prospective work is needed to clarify the direction and durability of these relationships and their implications for professional sustainability.
