WoS İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/8653
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Article Comparison of the Unmodified Rytov Method and the Modified Rytov Method in Obtaining Scintillations in Various Strongly Turbulent Media(Optica Publishing Group (Formerly OSA), 2026) Baykal, Y.The scintillation index as evaluated by the unmodified (classical) Rytov method solution for weak turbulence and evaluated by the modified or the extended Rytov method solution for strong turbulence is compared in different turbulent media, such as non-Kolmogorov atmospheric, non-Kolmogorov jet engine exhaust, marine atmospheric, and oceanic turbulences. When the scintillations are evaluated against the turbulence strength for various non-Kolmogorov power law and source sizes, the distinction between the modified Rytov and the unmodified Rytov method solutions, as the strength of turbulence increases, is clearly observed in all the turbulent media. This distinction is emphasized when the comparison is made at larger power law and source sizes. The results in this paper will be helpful in optical wireless communication system performance evaluations. © 2025 Optica Publishing Group.Article Field Correlations of a Gaussian Vortex Laser Beam in Vertical Turbulent Oceanic Links(Optica Publishing Group (Formerly OSA), 2026) Gerçekcioǧlu, H.; Baykal, Y.Utilizing the extended Huygens–Fresnel principle, field correlations of a Gaussian vortex beam propagating in the vertical turbulent oceanic link are examined analytically and evaluated by simulation in the Atlantic Ocean at low- and mid-latitude and high-latitude summer. Our formulation is based on the coherence length of a spherical wave operating at the depth range between 3000 and 3500 m. Variations in the rate of dissipation of turbulent kinetic energy per unit mass of fluid ε, the rate of dissipation of the mean-squared temperature χT, and the ratio of temperature to salinity contributions to the refractive index spectrum ω are taken into account at these depths in the underwater turbulent medium. The field correlation obtained using the coherence length found with the help of the depth-dependent power spectrum is expressed in detail. When the topological charge is selected considering the source size and propagation distance, it is seen that the normalized field correlation of the Gaussian vortex beam gives better results as compared to Gaussian beams. © 2025 Optica Publishing Group. All rights, including for text and data mining (TDM), Artificial Intelligence (AI) training, and similar technologies, are reserved.Article Beam Shaping on a Fluorescent On-Chip Imaging System(IOP Publishing Ltd, 2026) Arpali, Caglar; Arpali, Serap AltayThe fluorescent on-chip imaging system differs from a conventional fluorescent microscope in terms of the imaging method because the sample is directly placed on the imaging sensor (i.e., charge-coupled device (CCD)). While this imaging modality presents several advantages, including a wide field of view and rapid scanning speed, it can be difficult to detect certain particles in dense and scattering environments, such as whole blood and tissue. These difficulties lead to a decreased signal-to-noise ratio (SNR) in the captured images, influenced by both the medium's light-transmitting capability and the excitation techniques used. In this paper, we quantitatively examine the effect of beam shaping techniques on a fluorescent on-chip imaging system from the SNR perspective. An experimental comparison is conducted between a Gaussian beam and plane-wave illumination generated by a novel phase modulation schema using our developed imaging platform. The results indicate that the Gaussian beam produces higher SNR images than plane waves when detecting fluorescent particles in a microchannel. Gaussian beam's higher energy confinement ability enhances the image quality of on-chip fluorescent imaging systems, particularly involving scattering-like medium limitations.Article Citation - Scopus: 1Randomised Comparison Between Navigation and Non-Navigation Camera Control Performance in a Surgical Simulation Task Using a Haptic Device Interface(Wolters Kluwer Medknow Publications, 2026) Cagiltay, Nergiz Ercil; Topalli, Damla; Tuner, Emre; Berker, MustafaIntroduction:Navigation skills for controlling the camera in the surgical field are critical for many minimally invasive surgery (MIS) procedures. Currently, endoscopes lack integrated navigation aids, making camera control a challenging task. This experimental study aims to investigate the effect of navigation guidance on the performance of beginners.Patients and Methods:A custom computer-based simulation environment was developed for this study, featuring two conditions - one with navigation guidance and one without - focussed on a camera-cleaning task. Participants (64 beginners) were randomly assigned to one of these groups and used two haptic devices to simulate the endoscope and surgical tools.Results:Participants in the guided condition performed significantly better than those in the unguided condition. Notably, female participants completed the task in significantly less time under the guided condition compared to the unguided one.Conclusion:These findings suggest that incorporating navigation aids into endoscope interfaces could improve user performance, especially for beginners. Medical device manufacturers should consider adding navigation features to enhance usability. In addition, simulation-based instructional systems should integrate navigation aids to better support surgical training.Article Field Correlations in Jet Engine Exhaust Turbulence(Optica Publishing Group (Formerly OSA), 2026) Baykal, Y.Field correlations of collimated Gaussian beams are formulated and examined in jet engine exhaust turbulence. Variations of the field correlations are evaluated against the changes in the parameters of the wireless optical communication link and the jet engine exhaust turbulence. It is found that for all the link and turbulence parameters of interest, as the diagonal distance at the receiver plane increases, the field correlation decreases. Also, at the same diagonal distance from the receiver plane, field correlations tend to become smaller as the receiver points are at a larger distance from the receiver origin, at a smaller source size, wavelength, and inner scale values of jet engine exhaust turbulence. On the other hand, field correlations have a tendency to attain larger values at smaller link length, structure constant, amplitude coefficient for the additional high frequency spectrum area, outer scale of inhomogeneity, and the outer scale values of jet engine exhaust turbulence. © 2025 Optica Publishing Group. All rights, including for text and data mining (TDM), Artificial Intelligence (AI) training, and similar technologies, are reserved.Article Beam Moments of Higher-Order Annular Gaussian Beams in Tissue Turbulence(Optica Publishing Group, 2025) Arpali, Serap Altay; Arpali, Caglar; Baykal, YahyaBeam moments of the laser beam at the receiver plane were analyzed using our previously developed formula for the average light intensity of a higher-order annular Gaussian (HOAG) beam in the presence of biological tissue turbulence. HOAG beam moments are examined for the entities of power-in-the-bucket (PIB) and kurtosis across various tissue types such as the upper dermis (human), liver parenchyma (mouse), intestinal epithelium (mouse), and deep dermis (mouse). Moreover, beam moments are explored considering factors like the strength coefficient of the refractive-index fluctuations and the propagation distance. The PIB values for all HOAG beam modes are found to decrease exponentially and steadily, behaving similar to Gaussian beams as tissue length increases. As turbulence intensity increases, higher-order HOAG beam modes transfer optical energy to the receiver more efficiently than the lower order modes. Kurtosis analysis shows that at intermediate distances, the beam energy is distributed toward the edges, while at longer distances, the energy concentration is lower at the edges than at the center. This trend is reflected in increasing kurtosis values across all HOAG modes and tissue types. Considering the changes in PIB and kurtosis, higher-order HOAG modes transfer energy more conservatively within the tissue. Furthermore, the tissue type with the best transfer of optical power was observed to be the deep dermis (mouse). (c) 2025 Optica Publishing Group. All rights, including for text and data mining (TDM), Artificial Intelligence (AI) training, and similar technologies, are reserved.Article Laser Ablation Device with a Closed-Loop Control System(Optica Publishing Group, 2025) Beldek, Ulas; Erdogan, Kubra; Arpali, Caglar; Baykal, YahyaA laser ablation device with real-time beam power control is designed and implemented. This platform regulates the intensity of the laser beam by continuously measuring its intensity distribution. The quality of the ablation process is optimized through a closed-loop control system that uses a rule-based decision-making approach. The controller generates a starting signal for both the laser power and the motors based on the estimated quality of the ablation. The effects of laser power and light intensity on the formation of microchannels in polymethylmethacrylate material were investigated using the laser beam. The quality of the ablation geometry was assessed through image processing and inspection under a scanning electron microscope. The generated microchannels were analyzed in terms of roughness and residual thermal stress. A comparison of the experimental results with theoretical calculations and simulations revealed that the closed-loop control of laser beam power is effective for material etching and for creating smoother channel profiles. (c) 2025 Optica Publishing Group. All rights, including for text and data mining (TDM), Artificial Intelligence (AI) training, and similar technologies, are reserved.Article Citation - WoS: 8Citation - Scopus: 8Dimensions of Agitation Based on the Cohen-Mansfield Agitation Inventory in Patients With Dementia(Turkiye Sinir ve Ruh Sagligi dernegi, 2015) Altunoz, Umut; Baştuğ, Gülbahar; Ozel Kizil, Erguvan Tugba; Kirici, Sevinc; Bastug, Gulbahar; Bicer Kanat, Bilgen; Sakarya, Aysegul; Turan, Engin; Kanat Biçer, Bilgen; PsikolojiObjective: The aim of this study was to investigate the dimensions of agitation in dementia patients using the Turkish version of the Cohen-Mansfield Agitation Inventory (CMAI-T). Materials and Method: The study included 100 patients diagnosed as dementia, according to the DSM-IV-TR. The CMAI-T was administered to the patients' caregivers via face-to-face interviews. The Standardized Mini Mental State Examination (SMMSE) was used to assess cognitive functions. The severity of depression and the functional state of the patients were assessed using the Cornell Scale for Depression in Dementia (CSDD) and the Functional Activities Questionnaire (FAQ). Principal component analysis and varimax rotation were used to determine the factor structure of the CMAI-T. Results: Factor analysis of the CMAI-T indicated a 3-factor structure: physically aggressive agitation, verbal agitation, and physically non-aggressive agitation. In 92% of the patients there >= 1 was agitation behavior during the previous 2 weeks. The CMAI-T total and factor scores were negatively correlated with the SMMSE scores, and positively correlated with the CSDD and the FAQ scores. Conclusions: The CMAI-T yielded 3 factors (physically aggressive agitation, verbal agitation, and physically non-aggressive agitation), which indicated the scale had construct validity Agitation behaviors were associated with cognitive dysfunction, symptoms of depression and general level of functioning. Additional research is necessary to identify the predictors of these dimensions in different dementia samples, and to determine the efficacy of therapeutic interventions.Article Citation - WoS: 5Citation - Scopus: 3Intensity Fluctuations of Higher-Order Laser Modes in Jet Engine Exhaust Turbulence(Optica Publishing Group, 2025) Baykal, Yahya KemalIntensity fluctuations quantified by the scintillation index are evaluated in jet engine exhaust turbulence when higher-order laser modes are used in optical wireless communication links. The jet engine exhaust turbulence power spectrum, modified by low-pass and high-pass filters, is employed. Intensity fluctuations are evaluated against the link length, structure constant, wave number (inverse of wavelength) (i.e., against turbulence strength), source size, and jet engine exhaust turbulence parameters. It is found that higher-order laser modes are better at mitigating the scintillations. Jet engine exhaust turbulence parameters are found to affect scintillations substantially. (c) 2025 Optica Publishing Group. All rights, including for text and data mining (TDM), Artificial Intelligence (AI) training, and similar technologies, are reserved.Article Detection and Classification of Femoral Neck Fractures From Plain Pelvic X-Rays Using Deep Learning and Machine Learning Methods(Turkish Assoc Trauma Emergency Surgery, 2025) Sevinc, Huseyin Fatih; Ureten, Kemal; Karadeniz, Talha; Gultekin, Gokhan KorayBackground: Femoral neck fractures are a serious health concern, particularly among the elderly. The aim of this study is to diagnose and classify femoral neck fractures from plain pelvic X-rays using deep learning and machine learning algorithms, and to compare the performance of these methods. Methods: The study was conducted on a total of 598 plain pelvic X-ray images, including 296 patients with femoral neck fractures and 302 individuals without femoral neck fractures. Initially, transfer learning was applied using pre-trained deep learning models: VGG-16, ResNet-50, and MobileNetv2. Results: The pre-trained VGG-16 network demonstrated slightly better performance than ResNet-50 and MobileNetV2 for detecting and classifying femoral neck fractures. Using the VGG-16 model, the following results were obtained: 95.6% accuracy, 95.5% sensitivity, 93.3% specificity, 95.7% precision, 95.5% F1 Score, a Cohen's kappa of 0.91, and the Receiver Operating Characteristic (ROC) curve of 0.99. Subsequently, features extracted from the convolution layers of VGG-16 were classified using common machine learning algorithms. Among these, the k-nearest neighbor (k-NN) algorithm outperformed the others and exceeded the accuracy of the VGG-16 model by 1%. Conclusion: Successful results were obtained using deep learning and machine learning methods for the detection and classification of femoral neck fractures. The model can be further improved through multi-center studies. The proposed model may be especially useful for physicians working in emergency departments and for those not having sufficient experience in evaluating plain pelvic radiographs.