Department of Applied Mathematics (2012 - Present)
Physics - Engineering
Nano Science, Research Institute for Basic Sciences,
Physics
Physics, Sharif University of Technology,
Applied Physics
Physics, Sharif University, Tehran, Iran
I am currently a faculty member at the University of Tarbiat Modares, Department of Applied Mathematics (Biomathematics division), where I conduct research on the interdisciplinary area of the complex system especially on the modeling of brain and social network dynamics. In fact, my interests are how the brain works at the critical state and how this complex system synchronized under different conditions. Additionally, during the last years, I have also gained many skills in teaching (more than five different graduate courses) and supervising the graduate students. After finishing my Ph.D. thesis on the Brownian dynamics modeling of Kinesin bio-molecular motors, in 2009, I got two years postdoctoral research associate position at the University of California at Berkeley, Department of Bioengineering. During my postdoctoral appointment, I have focused on the development of multi-scale models in cell biology especially on the modeling of focal adhesion and nuclear pore complex. During this time, I have improved and my knowledge in the different computational modeling techniques like as agent-based modeling, cellular automata, mechanical modeling, and course gain simulation. Management of a research group and developing of the scientific software package are other advantages of postdoc other than my own research. I have also been actively involved in several successful efforts to raise funds for our research programs. In addition, I am involved in some experimental research on the brain-machine interface focuses on Cyborg (www.CyberneticOrganism.ir). Molecular Dynamics (MD) is one of my main expertise which I have been using it in my research since my MSc. Recently, I had four Ph.D. students which they used MD to model different transmembrane ion channels. Except of MD simulation which we usually use related software (GROMACS, NAMD, and LAMMPS), we write and use our own codes for simulation of complex system. I am passionate about programming and simulation, most of our codes are written with FORTRAN and Python.
Synchronization has an important role in neural networks, and their dynamics are mostly accompanied by cognitive activities such as memory, learning, and perception. These activities arise from the collective neural behaviors and are not totally understood yet. This paper aims to investigate a cortical model from this perspective. In this paper, we investigated a network of neural populations in a way the dynamics of each node corresponded to the Jansen-Rit neural mass model. First, we put this dynamic on a single mass of four different input levels. Then, we considered a Watts-Strogatz network of Jansen-Rit oscillators. We observed an epileptic activity in the weak input level. The network to change various parameters is considered. The de
Alzheimer’s disease (AD) is a progressive disorder associated with cognitive dysfunction that alters the brain’s functional connectivity. Assessing these alterations has become a topic of increasing interest. However, a few studies have examined different stages of AD from a complex network perspective that cover different topological scales. This study analyzed the trend of functional connectivity alterations from a cognitively normal (CN) state through early and late mild cognitive impairment (EMCI and LMCI) and to Alzheimer’s disease. The analyses had been done at the local (hubs and activated links and areas), meso (clustering, assortativity, and rich-club), and global (small-world, small-worldness, and efficiency) topological sca
A causal interpretation of the quantum world needs second quantization in order to cover phenomena like creation and annihilation of particles, and this leads to quantum field theory. The causal effects of the second quantization can be described through a new quantum potential. In this article we have dealt with the second quantization of Schrodinger and its effects on the path of a particle. This generalization leads to a modified Schrodinger which affects the particle through a modified quantum potential and a new term in the continuity equation. We have shown that these effects can provide a framework for the explanation of the creation and annihilation phenomena and other effects of quantum field theory on the development of a particle
The martensitic phase transformation in stoichiometric NiMn alloy and its shape memory effect is investigated using first principles method based on Density Functional Theory (DFT). The elastic properties of the B2 austenite and the L10 martensite phases were compared and the results indicated that the B2 phase has a low elastic shear modulus along the [110] direction giving rise to the formation of L10. Electronic density of states (DOS) calculations showed that the existence of the pseudo-gap appearing at the Fermi level which stabilizes the martensite phase against the austenite depends on both magnetism and the tetragonality ratio. Using geometrically nonlinear theory of martensite it was found that large volume change and twinning shea
How does society work? How do groups emerge within society? What are the effects of emotions and memory on our everyday actions? George Homans, like us, had a perspective on what society is, except that he was a sociologist. Homans theory, which is an exchange theory, is based on a few propositions about the fundamental actions of individuals, and how values, memory, and expectations affect their behavior. In this paper, our main interest and purpose are to find out whether these propositions can satisfy our conception of society and generate essential properties of it computationally. To do so, Based on Homans' prepositions, we provide the opportunity for each agent to exchange with other agents. That is, each agent transacts with familiar
Type 2 diabetes (T2D) is a challenging metabolic disorder characterized by a substantial loss of -cell mass via progressive programmed cell death and alteration of -cell function in the islets of Langerhans, disrupting insulin secretion and glucose homeostasis. The mechanisms for deficiency in -cell mass and function during the hyperglycemia development and T2D pathogenesis are complex. To study the relative contribution of -cell mass to -cell function in T2D, we make use of a comprehensive electrophysiological model from human -cell clusters. We find that defect in -cell mass causes a functional decline in single -cell, impairment in intra-islet synchrony, and changes in the form of oscillatory patterns of membrane potential and intracellu
Among the various types of lipid phases, the bilayer structure is of particular importance in understanding the processes associated with cell membranes such as lipid membrane fusion. Hence, the research in modeling of L_α lipid phase has been a significant part of the simulation of bio-macromolecules. In this study, we have exploited the systematic coarse-graining approaches for modeling of the 1,2- dioleoylphosphatidylethanolamine (DOPE) lipid molecule. The implicit solvent coarse-grained model of the lipid molecule is composed of 14 beads so that the potential energy of the system consists terms of bonded, non-bonded, and electrostatic. Constructing the Coarse-grained model was accomplished based on the atomistic simulation of lipid mol
Mind and brain/matter interaction is one of the important and controversial issues in Islamic philosophy. In fact, in the resources of Islamic philosophy, one of the basic parts of philosophical discussions is related to mind’s nature and its interaction with the brain. Especially, in Avicenna’s philosophy, there are many articles and books which have addressed the topic of mind and brain and the relation between them. Avicenna was a profound philosopher, an expert physicist and a proficient physician of his time. Because of his experimental proficiency in medicine and surgery and his deep philosophical analysis, his discussion about mind and brain is very interesting for our time, due to recent advances in neuroscience. In this article
In quantum approaches to consciousness, the authors try to propose a model and mechanism for the mind-brain interaction using modern physics and some quantum concepts which do not exist in the classical physics. The independent effect of mind on the brain has been one of the challenging issues in the history of science and philosophy. In some recent mind-brain interaction models, the direct influence of mind on matter is either not accepted (as in Stapp’s model) or not clear, and there have not been any clear mechanism for it (as in Penrose-Hameroff’s model or in Eccles’s model). In this manuscript we propose a model and mechanism for mind’s effect on the matter using an extended Bohmian quantum mechanics and Avicenna’s ideas. We
The magnetic properties of tetragonal structure of stoichiometric NiMn alloy is investigated using density functional theory within the local spin density approximation. The system studied here, is a free standing film. The effect of thickness and epitaxial strain on the magnetic and structural properties is examined. It is found that while the magnetic moments of Mn surface atoms vary depending on the number of layers being odd (3.60 μ B) or even (3.55 μ B) the magnitude of the magnetic moment for surface Ni atoms is constant (0.11 μ B). By applying epitaxial strain on the slabs, it was observed, for the first time, that the magnetic phase of NiMn films changes from “A-type-like” ferrimagnetic for compressive strains to “G-type-li
Nerve stimulation via micro-electrode implants is one of the neurostimulation approaches which is used frequently in the medical treatment of some brain disorders, neural prosthetics, brain-machine interfaces and also in the cyborg. In this method, the electrical stimulation signal can be categorized by the frequency band: low frequency, high frequency, and ultra-high frequency. The stimulation should be less destructive, more smooth, and controllable. In this article, we present a brief description of the mechanism underlying the ultra-high frequency stimulation. In the flowing, from an informatics perspective, we propose a state-of-the-art, low destructive, and highly efficient stimulation method at the low amplitude ultra-high frequency
Cyborg in the brain-machine interface field has attracted more attention in recent years. To control a creature via a machine called cyborg method, three stages are considerable: stimulation of neurons, neural response, and the behavioral reaction of the subject. Our main concern was to know how electrical stimulation induces neural activity and leads to a behavioral response. Additionally, we were interested to explore which type of electrical stimulation is optimal from different aspects such as maximum response with minimum induction stimulus field, minimum damage of the tissue and the electrode, reduction of the noxiousness of stimuli or pain in the living creature. In this article, we proposed a new model for the induction of neural ac
Lamellar and hexagonal lipid structures are of particular importance in the biological processes such as membrane fusion and budding. Atomistic simulations of formation of these phases and transitions between them are computationally prohibitive, hence development of coarse-grained models is an important part of the methodological development in this area. Here we apply systematic bottom-up coarse-graining to model different phase structures formed by 1,2-dioleoylphosphatidylethanolamine (DOPE) lipid molecules. We started from atomistic simulations of DOPE lipids in water carried out at two different water/lipid molar ratio corresponding to the lamellar Lα and inverted hexagonal HII structures at low and high lipid concentrations respectiv
In visual arts, painting is deeply reliant on the colour combination for its impact, depth and emotion. Recently, many studies have focused on image processing, regarding identification and classification of images, using some colour features such as saturation, hue, luminance and so forth. This study aims to delve into some of the painting styles from the perspective of graph theory and network science. We compared a number of famous paintings to find out the likely pattern that an artist uses for colour combination and juxtaposition. To achieve this aim, the digital image of a painting is converted to a graph where each vertex represents one of the painting’s colours. In this graph, two vertices would be adjacent if and only if
In quantum approaches to consciousness, the authors try to propose a model and mechanism for the mind-brain interaction using modern physics and some quantum concepts which do not exist in the classical physics. The independent effect of mind on the brain has been one of the challenging issues in the history of science and philosophy. In some recent mind-brain interaction models, the direct influence of mind on matter is either not accepted (as in Stapp's model) or not clear, and there have not been any clear mechanism for it (as in Penrose-Hameroff's model or in Eccles's model). In this manuscript we propose a model and mechanism for mind's effect on the matter using an extended Bohmian quantum mechanics and Avicenna's ideas. We show that
Background: Since brain structural connectivity is the foundation of its functionality, in order to understand the brain abilities, studying the relation between structural and functional connectivity is essential. Several approaches have been applied to measure the role of the structural connectivity in the emergent correlation/synchronization patterns. In this study, we indicate a link between the brain structural connectivity and its functional organization. Method: This paper investigates the cross-correlation and synchronization sensitivity to coupling strength between neural regions for different network topologies. We model the neural populations by a neural mass model that expresses an oscillatory dynamic. Results: The results highl
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