Growing Hemorrhagic Choroidal Fissure Cyst

Karatas, Ayse,Gelal, Fazil,Gurkan, Gokhan,Feran, Hamit The Korean Neurosurgical Society 2016 Journal of Korean neurosurgical society Vol.59 No.2

Choroidal fissure cysts are often incidentally discovered. They are usually asymptomatic. The authors report a case of growing and hemorrhagic choroidal fissure cyst which was treated surgically. A 22-year-old female presented with headache. Cranial MRI showed a left-sided choroidal fissure cyst. Follow-up MRI showed that the size of the cyst had increased gradually. Twenty months later, the patient was admitted to our emergency department with severe headache. MRI and CT showed an intracystic hematoma. Although such cysts usually have a benign course without symptoms and progression, they may rarely present with intracystic hemorrhage, enlargement of the cyst and increasing symptomatology.

Removal of hexavalent chromium using modified pistachio shell

Parlayici-Karatas, S.,Pehlivan, E. Techno-Press 2012 Advances in environmental research Vol.1 No.2

Pistachio shell (Pistacia vera) (PS), a low-cost material, has been utilized for the removal of the Cr(VI) ions after treatment with citric acid. Batch experimental steps were applied to obtain Cr(VI) ion adsorption details for the equilibrium between Cr(VI) and modified pistachio shell (MPS). The influences of contact time, pH, adsorbent dose and initial chromium concentration on the adsorption performance of MPS was investigated in detail. The results displayed that adsorption of Cr(VI) by MPS reached to equilibrium after 2 h and after that a little change of Cr(VI) removal efficiency was observed. The sorption percent is higher at lower pH and lower chromium concentration. Two possible mechanisms for reduction of Cr(VI) to Cr(III) can be suggested in Cr(VI) removal. In the first mechanism, Cr(VI) is reduced to Cr(III) by surface electron-donor groups of the adsorbent and the reduced Cr(III) forms complexes with adsorbent or remains in the solution. This Cr(III) is not adsorbed by adsorbent at pH 1.8. But in second mechanism, the adsorption-coupled reduction of Cr(VI) to Cr(III) occurred on the adsorbent sites. The equilibrium sorption capacity of Cr(VI) ion after 2 h was 64.35 mg/g for MPS.

Association of Early Favipiravir Use with Reduced COVID-19 Fatality among Hospitalized Patients

Ercan Karatas,Lacin Aksoy,Ersin Ozaslan 대한감염학회 2021 Infection and Chemotherapy Vol.53 No.2

Background: The antiviral agent favipiravir is an RNA-dependent RNA polymerase (RdRp) inhibitor. Materials and Methods: We examined patients with a clinical, laboratory, and radiological diagnosis of severe coronavirus disease 2019 (COVID-19) pneumonia. We investigated the effect of administering enteral favipiravir at a 2 × 1,600 mg loading dose and 2 × 600 mg maintenance dose for 5 days in addition to the standard COVID-19 treatment. Results: In total, 180 patients, who were hospitalized at the Istanbul Tuzla State Hospital and received favipiravir treatment between March 20, 2020 and May 30, 2020, were examined. Of these, 47 patients died. Thirty-three of the patients who died were aged over 65 years (70%), indicating that fatality was higher in elderly patients. Most of those who died had at least one comorbidity. Of the 101 patients who initiated favipiravir within ≤3 days of hospitalization, 17 died (17%). Of the 79 patients who initiated favipiravir after >3 days of hospitalization, 30 died (38%) (P = 0.002). Conclusion: We found that initiation of favipiravir within the first 72 h after the onset of disease symptoms reduced fatality in patients with COVID-19.

Relationship Between Bullying and Health Problems in Primary School Children

Hulya Karatas,Candan Ozturk 한국간호과학회 2011 Asian Nursing Research Vol.5 No.2

Purpose The aim of this study is to analyze the relationship between bullying and exposure to bullying and the health problems in the primary school children. Methods This study was conducted on 92 parents and 92 students who were sixth grade students in two primary schools in Izmir. The data were collected using the Peer Bullying Scale Adolescent Form and the Identification of Health Problems Form. The data were analyzed through χ2 analysis and odds ratios with a 95% confidence interval. Results About forty-nine percent of the students (48.9%) was male, 51.1% of them was female and the average age was 11.6 ± 0.53 years. It was found that students who had high scores for being exposed to bullying were significantly more likely to experience headache, feeling bad, crying restlessness, nervousness,sleeping problems, dizziness; whereas students who had high bullying scores were significantly more likely to experience only poor appetite. Conclusions Students exposed to bullying have more health problems than the bullying students. It is recommended that programs designed to prevent the negative effects of bullying be developed.

Logistics Research beyond 2000 : Theory, Method and Relevance

Cimen KARATAS-CETIN,Gul DENKTAS-SAKAR 한국해운물류학회 2013 The Asian journal of shipping and Logistics Vol.29 No.2

Logistics is a fertile field for scientific research constituting the application of various theories borrowed from the more established disciplines. There is an increasing need for the evaluation of the theory use in order to constitute a solid base for future development of the field. This paper seeks to elucidate the patterns of evolving logistics research since 2000 through the investigation of different theories and research methods employed. This study attempts to highlight the tension between the theories and the research methods employed in logistics discipline. It contributes to the current literature by providing an up-to-date outlook of the logistics research.

Decolorization of antraquinonic dye, Reactive Blue 114 from synthetic wastewater by Fenton process: Kinetics and thermodynamics

Mustafa Karatas,Yusuf Alparslan Argun,Mehmet Emin Argun 한국공업화학회 2012 Journal of Industrial and Engineering Chemistry Vol.18 No.3

In this work, the decolorization of C.I. Reactive Blue 114 (RB114), a commercially important anthraquinonic dye, by Fenton processes was investigated. The effects of operating parameters, such as Fe2+:H2O2 ratio, pH value, reaction time and temperature were examined. Maximum decolorization (86%) efficiencies were achieved at the Fe2+:H2O2 ratio of 0.1 and pH 3 for 20 min reaction time. The decolorization kinetic of RB114 followed pseudo-second-order reaction kinetic. The paper also discussed thermodynamic parameters including changes in Gibbs free energy, and activation energy for the decolorization of RB114 by Fenton and exposed that the oxidation process was spontaneous under natural conditions.

Application of Machine Learning in Prediction of Shear Capacity of Headed Steel Studs in Steel–Concrete Composite Structures

Cigdem Avci-Karatas 한국강구조학회 2022 International Journal of Steel Structures Vol.22 No.2

Headed studs are generally utilized as shear connectors at the interface between steel and concrete in composite structures primarily to transfer longitudinal shear force. This paper presents regression methodologies to predict the shear capacity of headed steel studs by using the concepts of minimax probability machine regression (MPMR) and extreme machine learning (EML). MPMR is carried out based on a minimax probability machine classifi cation. EML is an updated version of a single hidden layer feedforward network. From the experimental data presented in extensive literature, key input parameters infl uencing the shear capacity have been identifi ed and consolidated. The identifi ed parameters include (i) steel stud shank diameter, (ii) compressive strength of concrete, and (iii) tensile strength of headed steel stud. After careful examination of the data and their limits, about 70–75% of the mixed dataset comprising the range of the values has been used for developing MPMR and EML-based models. The input data has been normalized based on the limits of individual parameters. The remaining data has been utilized for verifi cation of the developed models. It is observed that the predicted shear strength capacity is comparable with the experimental observations. Further, the effi cacy of the models has been evaluated through several statistical parameters, namely; root mean square error, mean absolute error, the coeffi cient of effi ciency, root mean square error to observation’s standard deviation ratio, normalized mean bias error, performance index, and variance account factor. It is found that the R2 value is 0.9913 and 0.9479, respectively, for the models developed based on the concepts of MPMR and EML, indicating that the predicted value is closer to the experimental data.

Prediction of ultimate load capacity of concrete-filled steel tube columns using multivariate adaptive regression splines (MARS)

Cigdem Avci-Karatas 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.33 No.4

In the areas highly exposed to earthquakes, concrete-filled steel tube columns (CFSTCs) are known to provide superior structural aspects such as (i) high strength for good seismic performance (ii) high ductility (iii) enhanced energy absorption (iv) confining pressure to concrete, (v) high section modulus, etc. Numerous studies were reported on behavior of CFSTCs under axial compression loadings. This paper presents an analytical model to predict ultimate load capacity of CFSTCs with circular sections under axial load by using multivariate adaptive regression splines (MARS). MARS is a nonlinear and non-parametric regression methodology. After careful study of literature, 150 comprehensive experimental data presented in the previous studies were examined to prepare a data set and the dependent variables such as geometrical and mechanical properties of circular CFST system have been identified. Basically, MARS model establishes a relation between predictors and dependent variables. Separate regression lines can be formed through the concept of divide and conquers strategy. About 70% of the consolidated data has been used for development of model and the rest of the data has been used for validation of the model. Proper care has been taken such that the input data consists of all ranges of variables. From the studies, it is noted that the predicted ultimate axial load capacity of CFSTCs is found to match with the corresponding experimental observations of literature.

Modeling of Buckling Restrained Braces (BRBs) using Full-Scale Experimental Data

Cigdem Avci-Karatas,Oguz C. Celik,S. Ozmen Eruslu 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.10

Hysteretic performance of buckling restrained braces (BRBs) having various core materials, namely, steel and aluminum alloy and with various end connections are numerically investigated. As a computational tool, nonlinear finite element analyses (FEAs) are performed to better model the hysteretic behavior. For the simulation, various aspects such as 1) stress – strain relationship including the strain hardening effect 2) von Mises yield criterion 3) contact surface parameters between the core metal and surrounding high strength grout and 4) friction are defined. Experimental results from near-full scale cyclic tests on two steel core BRBs having steel casing as a restraining environment (named as BRB-SC4 and BRB-SC5) and an aluminum alloy core & aluminum alloy casing tube (named as BRB-AC3) are used in the analyses. All cyclically tested specimens have been designed according to AISC Seismic Provisions. Numerical results obtained from 3D models developed in ANSYS-Workbench give satisfactory response parameters when compared with the experimental ones (e.g., hysteretic curves, dissipated energies). Further, a convergence analysis regarding element numbers in the developed model is conducted for each BRB specimen. Finally, key issues that influence the hysteretic modeling of BRBs are identified.

Artificial Neural Network (ANN) Based Prediction of Ultimate Axial Load Capacity of Concrete-Filled Steel Tube Columns (CFSTCs)

Cigdem Avci-Karatas 한국강구조학회 2022 International Journal of Steel Structures Vol.22 No.5

Concrete-fi lled steel tube columns (CFSTCs) are preferred due to enhanced ductility and energy absorption. The capability of an artifi cial neural network (ANN) based analytical model on estimating the ultimate load capacity of circular CFSTCs under axial loadings has been investigated in this study. To provide a better prediction in modeling, 150 comprehensive experimental data were obtained from circular CFSTC’s geometrical and mechanical properties, such as height, diameter, thickness, the yield stress of steel, unconfi ned concrete strength, Young’s modulus of steel and concrete, etc., were examined. The backpropagation-training practice available in ANN was used to update the weights of each layer based on the network output error. For feedforward–backpropagation, the Levenberg–Marquardt algorithm was employed. The eff ectiveness of the ANN model was developed using general-purpose software MATLAB ® by training and predicting the ultimate load capacity of circular CFSTCs. Finally, about 75% of the data were used for ANN training, and the remaining 25% was used for testing the ANN model. The results show that the predicted values of ultimate load capacity using the ANN model agree well with that of the corresponding experimental observations, and the percentage diff erence is about ± 10%. Additionally, a new engineering index, a20-index, was predicted to further verify the reliability of the model. The fi ndings of this article are new and will signifi cantly contribute to the existing technology of ANN-based modeling in composite construction.