Özer, Mahmut | Uzuntarla, Muhammet | Ağaoğlu, Şükrüye Nihal

Article | 2006 | Physics Letters, Section A: General, Atomic and Solid State Physics360 ( 1 ) , pp.135 - 140

We first investigate the amplitude effect of the subthreshold periodic forcing on the regularity of the spiking events by using the coefficient of variation of interspike intervals. We show that the resonance effect in the coefficient of variation, which is dependent on the driving frequency for larger membrane patch sizes, disappears when the amplitude of the subthreshold forcing is decreased. Then, we demonstrate that the timings of the spiking events of a noisy and periodically driven neuron concentrate on a specific phase of the stimulus. We also show that increasing the intensity of the noise causes the phase probability densit . . .y of the spiking events to get smaller values, and eliminates differences in the phase locking behavior of the neuron for different patch sizes. © 2006 Elsevier B.V. All rights reserved Daha fazlası Daha az

Kaya, Gülhan Ustabaş | Erkaymaz, Okan | Saraç, Zehra

Article | 2016 | Expert Systems with Applications56 , pp.177 - 185

In this study, the optimization of the digital holography setup is achieved by a using fuzzy logic prediction system. In fact, when this optimization process is experimentally performed, some parameters are changed in the setup. These parameters affect directly the obtained image quality after a reconstruction process, which is determined by normalized root mean square. The aim of this study is to achieve the optimization of digital holographic setup by using both experimental and fuzzy logic prediction systems. Furthermore, the required time during the experimental optimization can be lowered by using a numerical method like the fu . . .zzy logic prediction system. Here, the experimental optimization results and the optimization results obtained by the fuzzy logic prediction system are compared. It is offered that the designed experimental system can be optimized by using an artificial intelligent tool. The applied fuzzy logic prediction model is used the first time for optimization of hologram recording setup. As a result, it is reached a conclusion that the optimization of digital holographic setup can be numerically performed by the fuzzy logic prediction system. Moreover, while digital holographic setup is experimentally designed, the required time for optimization is reduced, as well. © 2016 Elsevier Ltd. All rights reserved Daha fazlası Daha az

Onur, Tuğba Özge | Carlson, Johan E | Svanström, Erika | Hacıoğlu, Rıfat

Article | 2019 | Iranian Journal of Science and Technology - Transactions of Electrical Engineering43 ( 3 ) , pp.405 - 413

This paper demonstrates how flexural wave propagation in a thin plate can be modeled by estimating the combined effect of the excitation source signal and the impulse response of the ultrasonic sensor. The wave propagation in the plate is modeled using the wave equation for the flexural wave mode. A theoretical model for flexural wave propagation in thin plates has been derived, and it has been compared with measurements excited by tapping gently on the surface. The combined effects of the excitation source signal and the impulse response of the low-cost piezoelectric sensor are modeled using finite-impulse response and/or infinite- . . .impulse response filters. Thereafter, the performances of the selected filters are compared on estimating the wave propagation in a thin quartz glass plate. Results indicate that the most accurate estimation of wave propagation has been obtained using a linear phase filter which attributes all dispersions to the flexural wave. © 2018, Shiraz University Daha fazlası Daha az

Özer, Mahmut | Graham, Lyle J.

Article | 2008 | European Physical Journal B61 ( 4 ) , pp.499 - 503

https://dx.doi.org/10.1140/epjb/e2008-00095-y https://hdl.handle.net/20.500.12628/6161

Özer, Mahmut | Erdem, Rıza

Article | 2003 | NeuroReport14 ( 7 ) , pp.1071 - 1073

A voltage-gated ion channel is fundamental in generation and propagation of electrical signals in the excitable membranes. Dynamics of (in)activation gates of the ion channel is modeled by first-order kinetics. The equilibrium value function is crucial in the kinetics of the (in)activation gates for fitting experimental data. We present a new methodology to define the equilibrium value function based on the lowest approximation of the cluster variation method and the static properties in the molecular field approximation. The methodology allows for exploration of the gating dynamics. © 2003 Lippincott Williams & Wilkins.

Çalım, Ali | Hövel, Philipp | Özer, Mahmut | Uzuntarla, Muhammet

Article | 2018 | Physical Review E98 ( 6 ) , pp.1071 - 1073

Chimeras are complex spatiotemporal patterns that emerge as coexistence of both coherent and incoherent groups of coupled dynamical systems. Here, we investigate the emergence of chimera states in nonlocal networks of type-I Morris-Lecar neurons coupled via chemical synapses. This constitutes a more realistic neuronal modeling framework than previous studies of chimera states, since the Morris-Lecar model provides biophysically more relevant control parameters to describe the activity in actual neural systems. We explore systematically the transitions of dynamic behavior and find that different types of synchrony appear depending on . . . the excitability level and nonlocal network features. Furthermore, we map the transitions between incoherent states, traveling waves, chimeras, coherent states, and global amplitude death in the parameter space of interest. This work contributes to a better understanding of biological conditions giving rise to the emergence of chimera states in neural medium. © 2018 American Physical Society Daha fazlası Daha az

Özer, Mahmut

Article | 2005 | Physica A: Statistical Mechanics and its Applications357 ( 03.Apr ) , pp.397 - 414

In this study, we propose a theoretical framework for the determination of rate kinetics in the ion channels. In this framework, we firstly formulate the kinetic equation for the time-dependent open-state probability of the gate and forward and backward rate kinetics based on the path probability method with three parameters, explicitly. Then, we construct a tool to determine if fitted rate kinetics satisfy the experimental data by deriving kinetic coefficients of activation and inactivation gates based on the Onsager reciprocity theorem. The proposed framework is based on the principles of statistical physics and conceptually quite . . . different from those of conventional models. We also illustrate its applicability based on the empirical inactivation kinetics of T-type calcium channel from thalamic relay neurons, and then compare it with the linear and nonlinear thermodynamic models for the same calcium channel. The results of the present study indicate that our methodology suggests a general framework for the determination of rate kinetics in ion channels. © 2005 Elsevier B.V. All rights reserved Daha fazlası Daha az

Özer, Mahmut | İşler, Yalçın | Özer, Halil

Article | 2004 | Computer Methods and Programs in Biomedicine75 ( 1 ) , pp.51 - 57

In this paper, a new computer software package, Yalzer, is introduced for simulating single-compartmental model of neurons. Passive or excitable membranes with voltage-gated ion channels can be modeled, and current clamp and voltage clamp experiments can be simulated. In the Yalzer, first-order differential equations used to define the dynamics of the gate variables and the membrane potential are solved by two separate integration methods with variable time steps: forward Euler and exponential Euler methods. Outputs of the simulation are shown on a spreadsheet template for allowing flexible data manipulation and can be graphically d . . .isplayed. The user can define the model in detail, and examine the excitability of the model and the dynamics of voltage-gated ion channels. The software package addresses to ones who want to run simple simulations of neurons without need to any programming language skills or expensive software. It can also be used for educational purposes. © 2003 Elsevier Ireland Ltd. All rights reserved Daha fazlası Daha az

Uzuntarla, Muhammet | Torres, Joaquin J. | So, Paul | Özer, Mahmut | Barreto, Ernest

Article | 2017 | Physical Review E95 ( 1 ) , pp.51 - 57

We investigate the behavior of a model neuron that receives a biophysically realistic noisy postsynaptic current based on uncorrelated spiking activity from a large number of afferents. We show that, with static synapses, such noise can give rise to inverse stochastic resonance (ISR) as a function of the presynaptic firing rate. We compare this to the case with dynamic synapses that feature short-term synaptic plasticity and show that the interval of presynaptic firing rate over which ISR exists can be extended or diminished. We consider both short-term depression and facilitation. Interestingly, we find that a double inverse stocha . . .stic resonance (DISR), with two distinct wells centered at different presynaptic firing rates, can appear. © 2017 American Physical Society Daha fazlası Daha az

Uzun, Rukiye | Erkaymaz, Okan | Şenyer Yapıcı, İrem

Article | 2018 | Gazi University Journal of Science31 ( 1 ) , pp.100 - 110

The surface electromyography (sEMG) is useful tool to diagnose of knee disorder in clinical environments. It assists in designing the clinical decision support systems based classification. These systems exhibit complex structure because of sEMG data obtained at different postures at this study. In this context, we have researched the classification performance of each posture using artificial neural network (ANN) and logistic regression (LR) models and have showed that the classification success of the model used sitting posture data is higher than other postures (gait and standing). We have promoted this finding by using machine l . . .earning and statistical methods. The results show that the proposed models can classify with over 95% of success, and also the ANN model has higher performance than the LR model. Our ANN model outperforms reported studies in literature. The accuracy results indicate that the models used the only sitting posture data can exhibit successful classification for the knee disorder. Therefore, the usage of complex dataset is prevented for diagnosing knee disorder. © 2018, Gazi University Eti Mahallesi. All rights reserved Daha fazlası Daha az

Özer, Mahmut | Erdem, Rıza

Article | 2004 | Physica A: Statistical Mechanics and its Applications331 ( 01.Feb ) , pp.51 - 60

Dynamics of voltage-gated ion channels in the excitable cell membranes is formulated by the path probability method of nonequilibrium statistical physics and approaches of the system toward the steady or equilibrium states are presented. For a single-particle noninteractive two-state model, a first-order rate equation or dynamic equation is derived by introducing the path probability rate coefficients which satisfy the detailed balancing relation. Using known parameters for the batrachotoxin (BTX)-modified sodium channels in giand squid axon as an example, the rate equation is solved and voltage dependence of the time constant (?) a . . .nd its temperature effect are investigated. An increase in voltage caused a shift in ? towards shorter durations while increasing temperature caused a shift in time distribution towards longer durations. Results are compared with the kinetic model for the squid axon BTX-modified sodium channels by the cut-open axon technique and a very good agreement is found. © 2003 Elsevier B.V. All rights reserved Daha fazlası Daha az

Saraç, Zehra

Article | 2008 | Optics and Lasers in Engineering46 ( 11 ) , pp.823 - 828

This paper proposes the use of Stockwell transform for the analysis of white-light interferograms. The performance of Stockwell transform is assessed from the statistical parameters obtained by analyzing the simulated and experimental interferograms. Furthermore, the sensitivity of Stockwell transform to sampling, intensity and the phase noises is investigated. Results show that sampling and intensity noises significantly affect the performance of Stockwell transform. © 2008 Elsevier Ltd. All rights reserved.