Koleksiyon/r/gumushane/10001

Yayınlar

Koleksiyondaki öğeler

  • MakaleYalnız künye2017Scopus SJRQ1
    Stereo-based palmprint recognition in various 3D postures

    Bingöl, Özkan; Ekinci, Murat

    In order to increase performance in palmprint recognition systems, various devices are normally used to restrict the movement of the hand. These can cause problems, especially for those users with physical disabilities. They also cause significant hygiene problems in multi-user systems. Recently, studies on palmprint recognition systems have progressed towards the development of unconstrained, contactless and unrestricted background techniques. The most common problem encountered in these studies is the alignment arising from the free movement of the hand. Despite 3D hand-acquisition devices which offer extra recognition features to overcome this problem, the applicability of these devices is low because of their increased cost. In this study, a stereo camera was proposed. Although due to matching problems, it is difficult to achieve precise, distinct feature extraction in the unrestricted 3D environment used for palmprint recognition, the orientation of the hand in 3D space can be determined by obtaining depth information. In this study, the depth information was extracted by using the binocular stereo approach. First, the orientation of the hand was estimated by fitting a surface model associated with the eigenvectors of the depth information. Pose correction was then accomplished by establishing a relationship between the orientation and the images. The pose correction greatly relieved the perspective distortion that usually occurs within the various poses of the hands. Next, the region of interest was determined by performing segmentation on the corrected images using the Active Appearance Model (AAM). The palmprint features were then extracted via Gabor-based Kernel Fisher Discriminant Analysis. In order to demonstrate the performance of the proposed approach, a new dataset was compiled from stereo images within various scenarios collected from 138 different individuals. As a result of these experimental studies, the EER values, especially on the images captured from different hand orientations in 3D, were reduced from around 14–0.75%. With the help of this suggested approach, the palmprint recognition system was transformed into a more portable form by removing the closed-box mechanisms and equipment restricting movement of the hand. This system can automatically perform pose estimation, hand segmentation and recognition processes without any special intervention.

    AtıfScopus34WoS24
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  • MakaleAçık Erişim2018Scopus SJRQ1
    Primula vulgaris extract induces cell cycle arrest and apoptosis in human cervix cancer cells

    Demir, Selim; Turan, Ibrahim; Aliyazicioglu, Rezzan; Yaman, Serap Ozer; Aliyazicioglu, Yuksel

    Primula vulgaris belongs to the genus Primula, members of which are frequently used in folk medicine. Various studies have investigated the cytotoxic effect of different Primula species, but there have been limited studies on the cytotoxic effect of P. vulgaris. The aim of this study was to investigate the cytotoxic effects, and possible mechanisms involved, of P. vulgaris flower extract on human cervical cancer (HeLa) cells. The cytotoxic effect of the extract on HeLa cells was revealed using the MTT assay. Mechanisms involved in the extract's cytotoxic effect were then investigated in terms of apoptosis, mitochondrial membrane potential, and the cell cycle, using fluorometric methods. P. vulgaris flower extract exhibited selective cytotoxic effects against HeLa cells by arresting their cell cycle at the S phase, and inducing the number of apoptotic cells compared to normal fibroblast cells by reducing mitochondrial membrane potential in a concentration-dependent manner. This is the first study to reveal the antiproliferative effect of P. vulgaris flower extract. Further studies are now needed to identify the cytotoxic molecules in the extract and their mechanisms.

    • SDG 3 · Sağlık ve Kaliteli Yaşam
    AtıfScopus29WoS32OpenAlex40
    ScopusWeb of SciencePubMedİncele
  • MakaleAçık Erişim2016Scopus SJRQ3
    Increased expressions of eNOS and iNOS correlate with apoptosis of diabetic nephropathy in streptozotocin-induced type 1 diabetic rats; [Streptozotosin kaynaklı tip 1 diyabetik sıçanlarda meydana gelen nefropatilerde artan eNOS ve iNOS sunumlarının apoptozisle ilişkilendirilmesi]

    Dinçel, Güngör Çağdaş; Yildirim, Serkan

    The present study was designed to evaluate the effects of high level of nitric oxide (NO) production and oxidative stress (OS) on nephropathology and to identify whether NO and OS have any correlation with apoptosis seen in diabetic kidney, elucidating the underlying mechanism(s) involved in the development of nephropathology in streptozotocin (STZ)-induced diabetic rats. Expression levels of caspase 3, caspase 9, endothelial nitric oxide synthase (eNOS), inducible nitric oxide synthase (iNOS), 8-hydroxy-2′-deoxyguanosine (8-OHdG), for the detection of oxidative damage to DNA, were examined in diabetic kidney tissues. Results of the study revealed that the levels of 8-OHdG (P<0.005), eNOS (P<0.005), iNOS (P<0.005), caspase 3 (P<0.005) and caspase 9 (P<0.005) were remarkably higher in diabetic kidney tissues than in controls. In addition, STZ-treated animals showed significant loss of body weight and renal enlargement. It was suggested that apoptosis, OS and increased NO levels are involved in the pathogenesis of diabetic nephropathy. The results also strongly suggested that STZ-induced apoptosis through activation of the intrinsic pathway and that might be most likely related to increased NO levels. Moreover, high NO production was not only mediated by eNOS but also by iNOS. Increased NO production may contribute to hyperfiltration and microalbuminuria in early diabetic nephropathy. Furthermore, expression of 8-OHdG might give an idea of the progress and may be essential as it has a diagnostic significance for this disease. In conclusion, we believe that eNOS and iNOS overexpressions induce diabetic nephropathy by mediating apoptosis in STZ-induced rats.

    • SDG 3 · Sağlık ve Kaliteli Yaşam
    AtıfScopus4WoS4
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  • MakaleYalnız künye2019Scopus SJRQ1
    Enhancing of the nonlinear absorption and optical limiting performances of the phthalocyanine thin films by adding of the single walled carbon nanotubes in poly(methyl methacrylate) host

    Yuksek, Mustafa; Kaya, Elif Çelenk; Karabulutlu, Nur; Kaya, Ahmet Afşin; Karabulut, Mevlut; Elmali, Ayhan

    Unlike the earlier nonlinear optical studies of single walled carbon nanotubes (SWCNTs) which were generally carried out as solvent, in this study, we established to deposit the unsoluble SWCNTs as homogeneous thin films by blending them with phthalocyanines in PMMA host. The structural and morphological features of the thin films were studied by SEM and TEM imaging techniques while the linear, nonlinear-absorptions and carrier dynamic properties of the thin films were investigated with the UV–Vis spectrophotometer, open aperture Z-scan experiments and pump-probe technique, respectively. In addition, the optical limiting performances of the samples were calculated from nonlinear absorption spectra. It was observed that the linear- and nonlinear-absorptions and optical limiting performance of the thin films increased with the mixing of the SWCNT sample with the Pcs complexes. We have clearly explained the mechanisms contributing to the nonlinear optical absorption and optical limiting performances.

    AtıfScopus12WoS11OpenAlex10
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  • MakaleYalnız künye2016Scopus SJRQ4
    A semiautomatic segmentation approach to biometric measurement of the talus bone of sedentary women and ballerinas using CT images

    Reis, Hatice Catal; Bayram, Bulent; Seker, Dursun Zafer

    Background: Ballet produces much stress on bones in the feet of ballerinas. Monitoring and detecting talus bone deformation is important for their quality of health and profession. Objectives: To determine differences in the talus bone between ballerinas and sedentary women. Methods: We evaluated biometric differences in the talus bone of 5 ballerinas referenced to 5 similar sedentary women recruited into the present study. We acquired 20 multidetector computed tomographic images including right and left feet. Semiautomatic region-based image processing using 3D-Doctor (Able Software Corp) was used to create three-dimensional (3D) virtual models of the talus bones. Biometric measurements were made on the 3D models and statistical analysis conducted. Results: The mean talus bone length of ballerinas was 3.37 cm (SD 0.12; range 3.11 to 3.52). The talus bone length of sedentary women was 3.29 cm (SD 0.16; range 3.04 to 3.65), and tended to be shorter than that of the ballerinas (P = 0.08, t test). However, the test was insufficiently powered. The mean volume of the talus bones from the ballerinas was 24.8 cm3 (SD 0.83) and smaller than that from the sedentary women, 26.9 cm3 (SD 1.25) at P < 0.001 (t = 4.38, 18 degrees of freedom. Difference 2.1. Two-tailed 95% confidence interval for difference of means: 1.08 to 3.08). We found less variation in the feet of ballerinas than sedentary women. Conclusions: Volumetric measurements show that feet of ballerinas are smaller and retain similar shape and size than the irregular feet of sedentary women.

    • SDG 3 · Sağlık ve Kaliteli Yaşam
    AtıfScopus3OpenAlex1
    ScopusWeb of Scienceİncele
  • MakaleAçık Erişim2019Scopus SJRQ3
    Determination of antibiotic resistance genes and virulence factors in Escherichia coli isolated from Turkish patients with urinary tract infection

    Özad Düzgün, Azer; Okumuş, Funda; Saral, Ayşegül; Çopur Çiçek, Ayşegül; Cinemre, Sedanur

    Introduction: Escherichia coli ranks among the most common sources of urinary tract infections (UTI). Methods: Between November 2015 and August 2016, 90 isolates of E. coli were isolated from patients at Rize Education and Research Hospital in Turkey. Antibiotic susceptibility was determined for all isolates using the Kirby-Bauer disk diffusion method. These E. coli isolates were also screened for virulence genes, β-lactamase coding genes, quinolone resistance genes, and class 1 integrons by PCR. Results: With respect to the antibiotic resistance profile, imipenem and meropenem were effective against 98% and 90% of isolates, respectively. A high percentage of the isolates showed resistance against β lactam/β lactamase inhibitor combinations, quinolones, and cephalosporins. PCR results revealed that 63% (57/90) of the strains carried class 1 integrons. In addition, a high predominance of extended-spectrum β-lactamases (ESBLs) was observed. The qnrA, qnrB, and qnrS genes were found in 24 (26.6%), 6 (6.6%), and 3 (3.3%), isolates, respectively. The most common virulence gene was fim (82.2%).The afa, hly, and cnf1 genes were detected in 16.6%, 16.6%, and 3.3% of isolates, respectively. Moreover, we observed eleven different virulence patterns in the 90 E. coli isolates. The most prevalent pattern was fim, while hly-fim, afa-aer-cnf-fim, aer-cnf, afa-aer, and afacnf- fim patterns were less common. Conclusions: Most of the E. coli virulence genes investigated in this study were observed in E. coli isolates from UTI patients. Virulence genes are very important for the establishment and maintenance of infection.

    • SDG 3 · Sağlık ve Kaliteli Yaşam
    AtıfScopus28WoS19OpenAlex34
    ScopusWeb of SciencePubMedİncele
  • MakaleYalnız künye2022Scopus SJRQ1
    Major tectonic features and geodynamic setting of the Black Sea Basin: Evidence from satellite-derived gravity, heat flow, and seismological data

    Maden, Nafiz; Elmas, Ali

    The origin and development of the Black Sea Basin (BSB) remain controversial. In this study, we determined the main tectonic features of the BSB using satellite gravity, heat flow, and seismological data. Positive gravity anomalies are observed in the arc region due to high-density material, while negative gravity anomalies are seen in the trench region owing to the mass deficiency and sediments. The trench region has a relatively low heat flow anomalies along the Black Sea coasts. The Moho depth increases from 18.11 km in the Eastern Black Sea Basin (EBSB) to 51.83 km in the Eastern Anatolia Plateau (EAP) with an average of 34.13 ± 6.15 km. The lithosphere thickness changed between 78.48 km beneath Anatolia and 120.57 km below the EBSB with an average of 99.17 ± 8.17 km. The low heat flow and Moho temperature values indicate that the lithosphere is strong and cold beneath the BSB. The numerical results, therefore, provide evidence for southward subduction of the Tethys oceanic lithosphere below the Anatolian plate during the late Mesozoic-Cenozoic. Considering all geophysical and geological data, we conclude that the Black Sea Basin represents a relict basin, rather than a back-arc basin.

    AtıfScopus16WoS16OpenAlex14
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  • MakaleYalnız künye2022Scopus SJRQ2
    Economic Integration, Spatial Interaction and Labour Income Share: Evidence from the EU-13 Countries and the UK

    Çelik, Orkun; Karadağ, Metin

    We aim to investigate the effect of Single Market Programme on the spatial interaction of labour income share amongst the EU countries. Spatial panel data analysis is used for the aim of the study. The dataset is obtained from AMECO and WDI databases and covers the time period of 1960–2017. The results show that sign of spatial interaction between these countries in term of the labour income share has turned from positive to negative after the Single Market Programme. In other words, the Single Market Programme has induced to decrease the labour income share by negatively affecting the spatial interaction between these countries. In addition, we find that although the negative impacts of capital-output ratio and trade openness on the labour income share decrease, the negative impact of total factor productivity increases after the Single Market Programme. The results of robustness check also confirm our empirical findings.

    • SDG 8 · İnsana Yakışır İş ve Ekonomik Büyüme
    • SDG 10 · Eşitsizliklerin Azaltılması
    AtıfWoS1OpenAlex3
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  • MakaleYalnız künye2024Scopus SJRQ2
    The Effect of Video-Based Simulation Training on Nursing Students' Motivation and Academic Achievement A Mixed Study

    Koçan, Sema; Kulakaç, Nurşen; Aktug, Cemile; Demirel, Sevgül

    This study was conducted to determine the effect of video-based simulation education on nursing students' motivation and academic achievement. The research was designed in a mixed model. A quasi-experimental method with a pretest-posttest control group was used for the quantitative part, and the descriptive phenomenology approach was used as the qualitative research method. The sample of the study consisted of second-year nursing students in two state universities in eastern Turkey. The data were collected with the Student Information Form, the Academic Achievement Test, and the Motivation Resources and Problems Scale using Google Forms Web application. Qualitative data were collected through online semistructured interview forms and focus group interviews. According to the results, the posttest academic achievement and Motivation Resources and Problems Scale mean scores of the students in the intervention group were significantly higher than those of the control group (P < .05). In the analysis of the qualitative, three main themes emerged: We felt fortunate that it increased information retention,” “We felt like we were in real practice environment,” and “It made us feel that we were nurses.” The results showed the use of video-based simulation can be suggested as a strategy to promote classroom teaching and engage students.

    • SDG 3 · Sağlık ve Kaliteli Yaşam
    • SDG 4 · Nitelikli Eğitim
    AtıfScopus5WoS3OpenAlex4
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  • MakaleYalnız künye2022Scopus SJRQ1
    A multi-stage decision making model for determining a suitable innovation structure using an open innovation approach

    Yildirim, Ercan; AR, Ilker Murat; Dabić, Marina; Baki, Birdogan; Peker, Iskender

    This study seeks to form an end-to-end analysis of Open Innovation stages, developing a three-part consecutive multi-stage decision making model for a suitable innovation structure by linking the processes used to determine the innovation type (open, closed), the OI type (inbound, outbound, coupled), and the collaboration type (science-based, market-based). The decision-making criteria for the OI stage are determined by academic literature and finalized by Delphi technique. The criteria for relationships are determined through expert evaluation. The Fuzzy Analytic Network Process is applied in order to determine the weights and rankings. The most important criterion to consider when choosing the innovation type is open innovation awareness. For the OI type, the most important criterion is knowledge acquisition and, for collaboration, it is network building. This approach allows us to predict the potential risks or costs of the OI process and the possibility of decision errors can thus be reduced.

    • SDG 9 · Sanayi, Yenilikçilik ve Altyapı
    AtıfScopus24WoS16OpenAlex21
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  • MakaleAçık Erişim2024Scopus SJRQ2
    The novel numerical solutions for time-fractional Fornberg-Whitham equation by using fractional natural transform decomposition method

    Alkan, Aslı; Anaç, Halil

    The time-fractional partial differential equations were solved by the fractional natural transform decomposition method. Fractional derivatives are Caputo sense. The Fornberg-Whitham equation is a generalization of the Korteweg-de Vries (KdV) equation, which describes the propagation of long waves in shallow water. It includes higher-order dispersion terms, making it applicable to a wider range of dispersive media the fractional natural transform decomposition method (FNTDM) was also used to examine applications, and the solutions obtained by this method have been compared to those obtained by the variational iteration method, fractional variational iteration method, and homotopy perturbation method. In addition, the MAPLE package drew graphs of the solutions of nonlinear time-fractional partial differential equations, taking into account physics. The method described in this study exhibited a notable degree of computational precision and straightforwardness when used to the analysis and resolution of intricate phenomena pertaining to fractional nonlinear partial differential equations within the domains of science and technology.

    AtıfScopus10WoS6OpenAlex13
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  • MakaleAçık Erişim2023Scopus SJRQ4
    The Effect of a Musical Toy on Preschool Children’s Pain and Anxiety During Blood Collection; [Okul Öncesi Dönem Çocuklarında Kan Alma İşlemi Sırasında Işıklı Dönen Müzikli Oyuncağın Ağrı ve Anksiyeteye Etkisi]

    Kurudirek, Fatma; Demir İmamoğlu, Zeynep; Ekici, Sümeyye

    Objective: This study examined the effect of providing a lighted, rotating musical toy on preschool children’s pain and anxiety during a blood collection procedure. Methods: The randomized controlled study was conducted on a sample of children aged 4-6 years who applied to the blood collection unit of a state hospital in Turkey from July 1 through August 1, 2022. The data were obtained from 95 children who met the research criteria (48 in the control group and 47 in the intervention group). Stratification and block randomization methods were used to determine the experimental and control groups. The variables of gender and fear of interference were used in the stratification of the children. The Family and Child Information Form, Child Fear and Anxiety Inventory, and Wong–Baker Facial Expression Rating Scale were used to collect the data. Results: The pain scores of the children in the experimental group were found to be lower (1.42 ± 1.05) than those in the control group (2.81 ± 1.23), and the result was statistically significant (P < .001). During the procedure, the mean Child Fear and Anxiety Inventory score of the children in the experimental group (1.21 ± 0.97) was lower than that of the control group (2.72 ± 1.10), and the difference was statistically significant (P < .001). Conclusion: This study found that providing a lighted, rotating musical toy to children aged 4-6 during blood collection effectively reduced their pain and anxiety. In line with these results, it is recommended that nurses and parents use such a toy in blood collection units to reduce pain and anxiety in children.

    • SDG 3 · Sağlık ve Kaliteli Yaşam
    AtıfScopus4WoS3OpenAlex2TR Dizin1
    ScopusWeb of ScienceTR Dizinİncele
  • MakaleYalnız künye2022Scopus SJRQ2
    Effect of Working Conditions on the Lubricated Wear Behavior of Zn-40Al-2Cu-2Si Alloy in the As- Cast and T6 Heat-Treated States

    Savaskan, Temel; Hekimoglu, Ali Pasa; Azakli, Zeki; Calis, Merve

    In order to determine the effect of working conditions on the lubricated wear behavior of Zn-40Al-2Cu-2Si alloy in the as-cast and T6 heat-treated states, its tribological properties were studied at different oil flowrates, contact pressures, and sliding speeds in comparison with SAE 660 bronze. It was observed that the friction coefficient, temperature, and wear volume of both materials decrease, but their average surface roughness increase with increasing oil flowrate. As the pressure increased, the friction coefficient and average surface roughness of the experimental materials decreased, but their temperature and wear volume increased. It was also found that the working temperature of these materials increased, but their wear volume showed a decrement and a subsequent increment with increasing sliding speed. In addition, their wear volume and average surface roughness showed opposite changes with the sliding speed. Zn-40Al-2Cu-2Si alloy in both as-cast and heat-treated conditions showed lower wear volume and friction coefficient than SAE 660 bronze. This indicates that Zn-40Al-2Cu-2Si alloy can be used to manufacture diesel engine crankshaft journal bearings.

    AtıfScopus8WoS8OpenAlex10
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  • MakaleYalnız künye2022Scopus SJRQ2
    In vitro and in silico evaluation of some plant extracts and phytocompounds against multidrug-resistant Gram-negative bacteria

    Aydemir, Eda; Sarıyer, Emrah; Akyıldız, Esma; Özad Düzgün, Azer; Camadan, Yasemin; Saral Sarıyer, Ayşegül

    The spread of multidrug-resistant Gram-negative (MDR) bacteria is a global public health problem, as infections caused by MDR Gram-negative bacteria are difficult to treat. New antibiotic agents need to be developed to overcome this problem, and phytochemicals show promise at this point. In this study, methanol extracts were prepared from cinnamon, thyme, nettle, white tea, rosehip, and antibacterial activity of the methanol extracts was studied against two MDR Gram-Negative bacteria (K. pneumoniae and A. baumannii) by broth microdilution method. The MICs of methanol extracts of cinnamon, rosehip, thyme, white tea for A. baumannii were found as 0.015125 g/ml, 0.07825 g/ml, 0.030625 g/ml, 0.00796875 g/ml, respectively. It was found that only cinnamon methanol extract had antibacterial activity in the used extract concentrations against K. pneumoniae and the MIC value was 0.0605 g/ml. The effects of plant methanol extract with antibacterial activity and imipenem combinations were studied in vitro using the checkerboard method. The FIC Indexes were obtained from the checkerboard results and it was observed that the combination of methanol extract and imipenem showed an antagonistic or additive/indifferent effect but not a synergistic effect. We evaluated the binding affinity of epigallocatechin 3-gallate, quercetin, cinnamaldehyde, carvacrol, and thymol phytocompounds using in silico methods, which are well known as a phytocompounds in white tea, cinnamon, thyme, nettle, and rosehip and have antibacterial activities. The results suggested that these phytocompounds should be supported with in vivo and in vitro experiments to investigate their potential for being inhibitor candidates.

    • SDG 3 · Sağlık ve Kaliteli Yaşam
    AtıfScopus6WoS4OpenAlex6
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  • MakaleAçık Erişim2024Scopus SJRQ4
    Economic Evaluation of Thermal and Mechanical Activation Energies in Plaster Production

    Şener, Muhammed; Uysal, Turan; Erdemoğlu, Murat

    Plaster is among the most needed raw materials in the world. In this study, thermal activation provided by calcination and mechanical activation methods provided by intensive milling in the plaster production process were evaluated in terms of activation energy. In this context, the energies of laboratory-scale thermal and mechanical activation processes were calculated and these activation methods were evaluated economically and the ideal activation methods were determined. Although the mechanical activation method creates additional investment and operating costs, it reduces the calcination temperature by 13 °C, thus provides lower energy costs. Addition of a mechanical activator mill before thermal activation in plaster production as a more economical and more environmentally friendly method was proposed.

    • SDG 7 · Erişilebilir ve Temiz Enerji
    • SDG 9 · Sanayi, Yenilikçilik ve Altyapı
    • SDG 12 · Sorumlu Üretim ve Tüketim
    • SDG 13 · İklim Eylemi
    AtıfScopus1
    Scopusİncele
  • MakaleYayıncıda açık erişim2023Scopus SJRQ4
    Postoperative symptom management perceptions and coping experiences of individuals with prostate cancer

    Kazımoğlu, Hatem; Ulutaşdemir, Nilgün; Kulakaç, Nurşen; Uzun, Sevda

    Objective: This study aims to examine in depth the perceptions of postoperative symptom management and coping experiences of individuals with prostate cancer. Material-Method: The study was conducted with 15 individuals with prostate cancer using a phenomenological research design, which is a qualitative research design. Interviews were conducted via the WhatsApp application. Results: The data were analysed using Colaizzi's phenomenological method. In the data analysis, two categories, five main themes, and 15 sub-themes emerged. In the category of symptom management perception, there are themes of pain management processes, the use of complementary and alternative therapies and practices to cope with symptoms and improve quality of life. In the category of coping experiences, the themes of individual coping, interpersonal relations, and productivity were obtained. Conclusion: Our study suggests that individuals with prostate cancer have difficulty in symptom management in the postoperative coping process, but they managed them effectively with the support of their spouse, family, and health care professionals.

    • SDG 3 · Sağlık ve Kaliteli Yaşam
    AtıfScopus1WoS1OpenAlex1
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  • MakaleAçık Erişim2022Scopus SJRQ1
    Finite-Time Neuro-Sliding-Mode Controller Design for Quadrotor UAVs Carrying Suspended Payload

    Bingöl, Özhan; Güzey, Hacı Mehmet

    Due to the quadrotor’s underactuated nature, suspended payload dynamics, parametric uncertainties, and external disturbances, designing a controller for tracking the desired trajectories for a quadrotor that carries a suspended payload is a challenging task. Furthermore, one of the most significant disadvantages of designing a controller for nonlinear systems is the infinite-time convergence to the desired trajectory. In this paper, a finite-time neuro-sliding mode controller (FTNSMC) for a quadrotor with a suspended payload that is subject to parametric uncertainties and external disturbances is designed. By constructing a finite-time sliding mode controller, the quadrotor can follow the reference trajectories in finite time. Furthermore, despite time-varying nonlinear dynamics, parametric uncertainties, and external disturbances, a neural network structure is added to the controller to effectively reduce chattering phenomena caused by high switching gains, and significantly reduce the size of the control signals. Following the completion of the controller design, the system’s stability is demonstrated using the Lyapunov stability criterion. Extensive numerical simulations with various scenarios are run to demonstrate the effectiveness of the proposed controller.

    AtıfScopus28WoS22OpenAlex21
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  • MakaleAçık Erişim2024Scopus SJRQ1
    Optimizing Memristor-Based Synaptic Devices for Enhanced Energy Efficiency and Accuracy in Neuromorphic Machine Learning

    Gökgöz, Baki; Aydin, Tolga; Gül, Fatih

    The traditional Von Neumann computing architecture, which necessitates data transfer between external memory and the processor, incurs significant energy and time costs when running deep learning (DL) and machine learning (ML) architectures. The primary issue with the energy and time efficiency of this architecture stems from the frequent and intensive data transfers between memory and the processor. Therefore, memristive synaptic devices are utilized to overcome this energy and time inefficiency while performing cognitive tasks. The fundamental working principle of memristive devices is to reduce the need for data transfer by combining memory and processing in the same location, thereby significantly decreasing both energy consumption and the time required for operations. However, to achieve the desired level of efficiency in terms of energy and time consumption from neuromorphic systems, the performance of these systems needs to be further improved with respect to accuracy and test error rates for classification applications. Achieving high accuracy performance in such deep learning or machine learning models necessitates optimization processes not only at the hardware level but also at the algorithmic level. In this context, this paper presents a comprehensive examination and comparison of the frequently used SGD and its momentum variants for deep learning and machine learning applications in memristor-based neuromorphic computing systems. The study thoroughly investigates the performance of critical metrics such as the learning properties, energy efficiency, and accuracy rates of the nano-scale titanium dioxide (TiO2) based synaptic device. The experimental results for the MNIST dataset showed AdaDelta 89.48%, AdaGrad 79.00%, Adam 79.13%, AdaMax 79.68%, Momentum 88.55%, Nadam 81.20%, RMSprop 84.91% and SGD 89.47% accuracy. The experimental results for the CIFAR dataset showed AdaDelta 90.51%, AdaGrad 82.08%, Adam 83.10%, AdaMax 81.76%, Momentum 91.25%, Nadam 82.45%, RMSprop 88.11% and SGD 90.21% accuracy. 2024 The Authors. This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

    AtıfScopus11WoS8OpenAlex13
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  • MakaleYalnız künye2023Scopus SJRQ2
    LC-HRMS Profiling and Phenolic Content, Cholinesterase, and Antioxidant Activities of Terminalia citrina

    Özler, Ebubekir; Topal, Fevzi; Topal, Meryem; Öztürk Sarıkaya, Sevim Beyza

    Terminalia citrina (T. citrina) belongs to the Combretaceae family and is included in the class of medicinal plants in tropical countries such as Bangladesh, Myanmar, and India. The antioxidant activities of lyophilized water (WTE) and alcohol extracts (ETE) of T. citrina fruits, their phenolic content by LC-HRMS, and their effects on cholinesterases (ChEs; AChE, acetylcholinesterase, and BChE, butyrylcholinesterase) were investigated. Especially ten different analytical methods were applied to determine the antioxidant capacity. Compared with similar studies for natural products in the literature, it was determined that both WTE and ETE exhibited strong antioxidant capacity. Syringe and ellagic acids were higher than other acids in ETE and WTE. IC50 values for ETE and WTE in DPPH radical and ABTS⋅+ scavenging activities were calculated as 1.69–1.68 μg mL−1 and 6.79–5.78 μg mL−1, respectively. The results of the biological investigations showed that ETE and WTE had an inhibition effect against ChEs, with IC50 values of 94.87 and 130.90 mg mL−1 for AChE and 262.55 and 279.70 mg mL−1 for BChE, respectively. These findings indicate that with the prominence of herbal treatments, T. citrina plant may guide the literature in treating Alzheimer's Disease, preventing oxidative damage, and mitochondrial dysfunction.

    • SDG 3 · Sağlık ve Kaliteli Yaşam
    AtıfScopus13WoS8OpenAlex14
    ScopusWeb of SciencePubMedİncele
  • MakaleAçık Erişim2023Scopus SJRQ3
    Agreement Between Nurses’ Anxiety And Depression Levels And Their Compliance With Isolation Measures During The Covid 19 Pandemic: An Online Cross-Sectional Study

    Demir Doğan, Melike; Aydin Sayilan, Aylin; Sayilan, Samet

    Aims: The purpose of this study was to determine the relationship between nurses’ anxiety and depression levels and their compliance with isolation measures during the COVID-19 pandemic. Background: The global COVID-19 pandemic has had severe psychological impacts on nurses. Methods: Following receipt of the requisite approvals, data were collected actively from 289 nurses consenting to participate in the study through an online questionnaire using theinternet/ social media. Results: Mean stress, anxiety, and depression scores were higher among carers for COVID-19 patients than in non-Covidcarers. Analysis revealed significant positive correlation between Isolation Precautions Compliance Scale scores and stress, anxiety, depression, and burnout. Conclusion: Burnout increased while compliance with isolation precautions decreased in this study as stress, anxiety, and depression increased.

    • SDG 3 · Sağlık ve Kaliteli Yaşam
    AtıfScopus12WoS9OpenAlex5
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