Yayın 109 Araştırmacı 1291

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Bulunan: 109 Adet 0.087 sn

Yazar : Özer, Mahmut ✕

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Konjestif kalp yetmezliği teşhisinde kullanılan çapraz doğrulama yöntemlerinin sınıflandırıcı performanslarının belirlenmesine olan etkilerinin karşılaştırılması

Narin, Ali | İşler, Yalçın | Özer, Mahmut

Konjestif kalp yetmezliği (KKY) vücudun ihtiyaç duyduğu miktarda kanın pompalanamaması durumudur. Bu tanıya sahip hastaların ölüm oranı çok yüksek olduğundan erken teşhis önemlidir. Bu amaçla gerçekleştirilen sınıflandırma algoritmalarının performanslarının ölçümü için farklı doğrulama yöntemleri vardır. Bu çalışmada, KKY hastalarının teşhisinde sık kullanılan 5 farklı sınıflandırıcının performans ölçümleri için k-parçalı ve birisi-dışarıda çapraz doğrulama yöntemleri denenmiştir. Her algoritma 100 defa denenerek ortalama başarım ve standart sapmaları kayıt edilmiştir. Sonuç olarak, çapraz doğ ...Daha fazlası

Diğer 2014 Dokuz Eylül Üniversitesi Mühendislik Fakültesi Fen ve Mühendislik Dergisi16 ( 48 ) , pp. 1 - 8 656 Görüntülenme

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Phase-plane analysis for a simplified model of Purkinje cell dendrite

Özer, Mahmut

In this study, phase-plane analysis is carried out for a simplified model of Purkinje cell dendrite in terms of voltage-gated ionic channels involved. State variables, nullclines and equilibrium points of the model are determined, and effects of ionic channel conductance and injected current on the shape of nullclines and the equilibrium points are investigated. In this study, phase-plane analysis is carried out for a simplified model of Purkinje cell dendrite in terms of voltage-gated ionic channels involved. State variables, nullclines and equilibrium points of the model are determined, and ...Daha fazlası

Bildiri 2003 Mathematical and Computational Applications8 ( 1-3 ) , pp. 7 - 78 583 Görüntülenme

Performance of small-world feedforward neural networks for the diagnosis of diabetes

Erkaymaz, Okan | Özer, Mahmut | Perc, Matjaž

We investigate the performance of two different small-world feedforward neural networks for the diagnosis of diabetes. We use the Pima Indians Diabetic Dataset as input. We have previously shown than the Watts–Strogatz small-world feedforward neural network delivers a better classification performance than conventional feedforward neural networks. Here, we compare this performance further with the one delivered by the Newman–Watts small-world feedforward neural network, and we show that the latter is better still. Moreover, we show that Newman–Watts small-world feedforward neural networks yiel ...Daha fazlası

Makale 2017 Applied Mathematics and Computation311 , pp. 2 - 28 728 Görüntülenme

Impact of small-world network topology on the conventional artificial neural network for the diagnosis of diabetes

Erkaymaz, Okan | Özer, Mahmut

Artificial intelligent systems have been widely used for diagnosis of diseases. Due to their importance, new approaches are attempted consistently to increase the performance of these systems. In this study, we introduce a new approach for diagnosis of diabetes based on the Small-World Feed Forward Artificial Neural Network (SW- FFANN). We construct the small-world network by following the Watts-Strogatz approach, and use this architecture for classifying the diabetes, and compare its performance with that of the regular or the conventional FFANN. We show that the classification performance of ...Daha fazlası

Makale 2016 Chaos, Solitons and Fractals83 , pp. 1 - 185 663 Görüntülenme

A computer software for simulating single-compartmental model of neurons

Özer, Mahmut | İşler, Yalçın | Özer, Halil

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 da ...Daha fazlası

Makale 2004 Computer Methods and Programs in Biomedicine75 ( 1 ) , pp. 5 - 57 802 Görüntülenme

Erişime Açık

Delayed feedback and detection of weak periodic signals in a stochastic Hodgkin-Huxley neuron

Yılmaz, Ergin | Özer, Mahmut

We study the effect of the delayed feedback loop on the weak periodic signal detection performance of a stochastic Hodgkin-Huxley neuron. We consider an electrical autapse characterized by its coupling strength and delay time. The stochastic Hodgkin-Huxley neuron exhibits subthreshold oscillations, and thus has an intrinsic time scale with the subthreshold oscillations. Therefore, we investigate the interplay of the subthreshold oscillations, coupling strength and delay time on the weak periodic signal detection. Results indicate that the delayed feedback either enhances or suppresses the weak ...Daha fazlası

Makale 2015 Physica A: Statistical Mechanics and its Applications421 , pp. 4 - 462 339 Görüntülenme

Effect of channel noise on the time-course of recovery from inactivation of sodium channels

Özer, Mahmut | Ekmekçi, N. Hakan

Ion channel noise that stems from the stochastic nature of the channel has important effects on neuronal dynamics. In this context, we examine the effect of the channel noise on the time-course of recovery from inactivation of sodium channels by using a stochastic extension of the Hodgkin-Huxley model. We show that the channel noise provides both some amount of the non-inactivated channels and a smaller time-course for recovering from inactivation leading to an increased maximal sodium conductance compared to deterministic one. © 2005 Elsevier B.V. All rights reserved.

Makale 2005 Physics Letters, Section A: General, Atomic and Solid State Physics338 ( 2 ) , pp. 1 - 154 720 Görüntülenme

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Stochastic resonance on Newman-Watts networks of Hodgkin-Huxley neurons with local periodic driving

Özer, Mahmut | Perc, Matjaž | Uzuntarla, Muhammet

We study the phenomenon of stochastic resonance on Newman-Watts small-world networks consisting of biophysically realistic Hodgkin-Huxley neurons with a tunable intensity of intrinsic noise via voltage-gated ion channels embedded in neuronal membranes. Importantly thereby, the subthreshold periodic driving is introduced to a single neuron of the network, thus acting as a pacemaker trying to impose its rhythm on the whole ensemble. We show that there exists an optimal intensity of intrinsic ion channel noise by which the outreach of the pacemaker extends optimally across the whole network. This ...Daha fazlası

Makale 2009 Physics Letters, Section A: General, Atomic and Solid State Physics373 ( 10 ) , pp. 9 - 968 729 Görüntülenme

Erişime Açık

Autapse-induced multiple coherence resonance in single neurons and neuronal networks

Yılmaz, Ergin | Özer, Mahmut | Baysal, Veli | Perc, Matjaž

We study the effects of electrical and chemical autapse on the temporal coherence or firing regularity of single stochastic Hodgkin-Huxley neurons and scale-free neuronal networks. Also, we study the effects of chemical autapse on the occurrence of spatial synchronization in scale-free neuronal networks. Irrespective of the type of autapse, we observe autaptic time delay induced multiple coherence resonance for appropriately tuned autaptic conductance levels in single neurons. More precisely, we show that in the presence of an electrical autapse, there is an optimal intensity of channel noise ...Daha fazlası

Makale 2016 Scientific Reports6 715 Görüntülenme

Erişime Açık

Dynamical structure underlying inverse stochastic resonance and its implications

Uzuntarla, Muhammet | Cressman John R. | Özer, Mahmut | Barreto, Erenest

We investigate inverse stochastic resonance (ISR), a recently reported phenomenon in which the spiking activity of a Hodgkin-Huxley model neuron subject to external noise exhibits a pronounced minimum as the noise intensity increases. We clarify the mechanism that underlies ISR and show that its most surprising features are a consequence of the dynamical structure of the model. Furthermore, we show that the ISR effect depends strongly on the procedures used to measure it. Our results are important for the experimentalist who seeks to observe the ISR phenomenon. © 2013 American Physical Society ...Daha fazlası

Makale 2013 Physical Review E - Statistical, Nonlinear, and Soft Matter Physics88 ( 4 ) 816 Görüntülenme

Epilepsy diagnosis using probability density functions of EEG signals

Orhan, Umut | Hekim, Mahmut | Özer, Mahmut | Provaznik, Ivo

In this paper, the equal frequency discretization (EFD) based probability density approach was proposed to be used in the diagnosis of epilepsy from electroencephalogram (EEG) signals. For this aim, EEG signals were decomposed by using the discrete wavelet discretization (DWT) method into subbands, the coefficients in each subband were discretized to several intervals by EFD method, and the probability density of each subband of each EEG segment was computed according to the number of coefficients in discrete intervals. Then, two probability density functions were defined by means of the curve ...Daha fazlası

Bildiri 2011 INISTA 2011 - 2011 International Symposium on INnovations in Intelligent SysTems and Applications , pp. 6 - 630 880 Görüntülenme

Erişime Açık

Effect of sub-threshold stimuli on neuronal dynamics

Ekmekçi N. Hakan | Özer, Mahmut

Voltage-gated ion channels are of great importance in the generation and propagation of electrical signals in the excitable membranes. In this study, we introduce the stochastic version of the Hodgkin-Huxley formalism and investigate the effect of channel noise on neuronal dynamic behaviors based on a model with the Gaussian noise. We show that the channel noise may result in a spiking activity for subthreshold stimulus, and that the firing dynamics follows more regular patterns when the membrane patch becomes smaller. It is also shown that the stochastic model converges to the deterministic m ...Daha fazlası

Bildiri 2005 Proceedings of the IEEE 13th Signal Processing and Communications Applications Conference, SIU 20052005 , pp. 1 - 146 464 Görüntülenme