From Discrete to Continuous: Modeling Volatility of the Istanbul Stock Exchange Market with GARCH and COGARCH

The objective of this paper is to model the volatility of Istanbul Stock Exchange market, ISE100 Index by ARMA and GARCH models and then take a step further into the analysis from discrete modeling to continuous modeling. Through applying unit root and stationary tests on the log return of the index, we found that log return of ISE100 data is stationary. Best candidate model chosen was found to be AR(1)~GARCH(1,1) by AIC and BIC criteria. Then using the parameters from the discrete model, COGARCH(1,1) was applied as a continuous model

From Discrete to Continuous: Modeling Volatility of the Istanbul Stock Exchange Market with GARCH and COGARCH

The objective of this paper is to model the volatility of Istanbul Stock Exchange market, ISE100 Index by ARMA and GARCH models and then take a step further into the analysis from discrete modeling to continuous modeling. Through applying unit root and stationary tests on the log return of the index, we found that log return of ISE100 data is stationary. Best candidate model chosen was found to be AR(1)~GARCH(1,1) by AIC and BIC criteria. Then using the parameters from the discrete model, COGARCH(1,1) was applied as a continuous model.ISE100,IMKB100,GARCH Modeling,COGARCH Modeling,discrete modeling,continuous modeling

Development of a structured approach for decomposition of complex systems on a functional basis

YesThe purpose of this paper is to present the System State Flow Diagram (SSFD) as a structured and coherent methodology to decompose a complex system on a solution-independent functional basis. The paper starts by reviewing common function modelling frameworks in literature and discusses practical requirements of the SSFD in the context of the current literature and current approaches in industry. The proposed methodology is illustrated through the analysis of a case study: design analysis of a generic Bread Toasting System (BTS)

Antibiotic resistance profile of Enterococcus faecium and Enterococcus faecalis isolated from broiler cloacal samples

WOS: 000399874200009The present study was performed to isolate and identify Enterococcus spp. from broiler cloacal samples to species level, to determine their resistance patterns to various antibiotics, and to detect vancomycin resistance genes. Cloacal samples of broilers collected from slaughterhouses were inoculated in Slanetz and Bartley agars with and without vancomycin (6 mu g/mL). Antibiotic resistance/susceptibility testing of the isolated and identified enterococci was performed by using the disk diffusion test. Multiplex PCR was used to identify the species and to detect vancomycin resistance genes. The majority of the isolated enterococci was Enterococcus faecium (60.43%, n = 142) and Enterococcus faecalis (33.62%, n = 79). E. casseliflavus and E. gallinarum were identified from 8 (3.42%) and 6 (2.56%) isolates, respectively. It was found that 88.9% of the enterococci were resistant to tetracycline and 83.4% of them were resistant to erythromycin. As a result, none of the strains isolated from cloacal samples of broilers carried the vanA and vanB genes. It was observed that 54.9% of E. faecium isolates and 78.4% of E. faecalis isolates were multidrug resistant (resistant to 3 or more antibiotic groups). The lack of vancomycin-resistant Enterococcus among the enterococci isolates was important for public health.Kirikkale UniversityKirikkale University [2012 / 46]The authors thank Kirikkale University (project number: 2012 / 46) for supporting this work

Function Modelling of Complex Multidisciplinary Systems. Development of a System State Flow Diagram Methodology for Function Decomposition of Complex Multidisciplinary Systems

The complexity of technical systems has increased significantly in order to address evolving customer needs and environmental concerns. From a product development process viewpoint, the pervasive nature of multi-disciplinary systems (i.e. mechanical, electrical, electronic, control, software) has brought some important integration challenges to overcome conventional disciplinary boundaries imposed by discipline specific approaches. This research focuses on functional reasoning, aiming to develop a structured framework based on the System State Flow Diagram (SSFD) for function modelling of complex multidisciplinary systems on a practical and straightforward basis. The framework is developed at two stages. 1) The development of a prototype for the SSFD framework. The proposed SSFD framework are tested and validated through application to selected desktop case studies. 2) Further development and extension of the SSFD framework for the analysis of complex multidisciplinary systems with multiple operation modes and functional requirements. The developed framework is validated on real world case studies collaborated with industrial partners. The main conclusion of this research is that the SSFD framework offers a rigorous and coherent function modelling methodology for the analysis of complex multidisciplinary systems. Further advantages of the SSFD framework is that 1) the effectiveness of the Failure Mode Avoidance (FMA) process can be enhanced by integrating the SSFD framework with relevant tools of the FMA process, and 2) the integration of the SSFD with the SysML systems engineering diagrams is doable, which can promote the take-up of the approach in industry.Automotive Research Centr

The link between learning performance, immobility in the forced swim test, and hippocampal glia

Aim: To obtain maximal translational insights from animal models of depression, we need to know the meaning of behavioral parameters of animal models. The extent of construct and face validities of behavioral despair in the form of behavioral immobility in forced swim test (FST) is disputed. In this study, learning performance in a dual solution T-Maze and immobility on the 2nd day of FST was compared to shed light on this debate. Furthermore, we aimed to inspect the relationship between hippocampal glial densities and behaviors observed. Method: Twelve adult male Sprague Dawley rats were tested in the dual-solution T-Maze and in FST. Subsequently, hippocampal slices were obtained, astrocyte and microglia cells were stained, and the densities were calculated for each subject. Results: The rats utilized different learning strategies to solve the T-Maze. But irrespective of strategy, the rats that exhibited an overall efficiency in their learning performance, remained immobile for longer durations on the 2nd day of the FST. No significant relationship was detected between hippocampal microglia and behavioral indices in T-Maze and FST. However, we detected a significant positive correlation with CA1 astrocyte density and T-Maze learning and dentate gyrus CA1 astrocyte density and headshake behavior in FST. Conclusions: The subjects showing a better cognitive performance in the T-Maze were immobile longer in the FST. This observation raises doubts about immobility as depression index and posits that it might reflect better learning. Our results also suggest that hippocampal glia cell types are differentially involved in cognition and affect

From Discrete to Continuous: Modeling Volatility of the Istanbul Stock Exchange Market with GARCH and COGARCH

The objective of this paper is to model the volatility of Istanbul Stock Exchange market, ISE100 Index by ARMA and GARCH models and then take a step further into the analysis from discrete modeling to continuous modeling. Through applying unit root and stationary tests on the log return of the index, we found that log return of ISE100 data is stationary. Best candidate model chosen was found to be AR(1)~GARCH(1,1) by AIC and BIC criteria. Then using the parameters from the discrete model, COGARCH(1,1) was applied as a continuous model

Functional Modelling of Systems with Multiple Operation Modes: Case Study on an Active Spoiler System

YesThis article presents the application of the Enhanced Sequence Diagram (ESD) for the analysis of the functionality of a system with shape-changing aspects in the context of its multiple operational modes, considering an active rear spoiler as a case study. The article provides new insights on the ESD support for model-based capture and articulation of functional requirements across multiple operation modes of the same system, with appropriate detail on attributes and metrics, and the alignment of these attributes and metrics in line with the concept of time through scope lines. The article also provides a comprehensive argument and discussion, exemplified based on the case study, for the support that the ESD provides for early systems functional and architecture analysis, within the context of a broader model-based Failure Mode Analysis methodology

Towards an Integrated Approach to Verification and Model-Based Testing in System Engineering

yesEngineering design in general and system design of embedded software have a direct impact on the final engineering product and the software implementation, respectively. Guaranteeing that the models utilised meet the specified requirements is beneficial in detecting misbehaviour and software flaws. This requires an integrated approach, combining verification and model-based testing methodology and notations and methods from system engineering and software engineering. In this paper, we propose a model-based approach integrating various notations utilised in the functional design of complex systems with formal verification and testing. We illustrate our approach on the cruise control system of an e-Bike case study