Papers by Vladimir Miljkovic
Exact and Monte Carlo study of the two self-avoiding random walks on the three-dimensional Sierpinski lattices
Nucleation and Atmospheric Aerosols, 2007
We consider the phenomena of entanglement of the two interacting self-avoiding walks (SAW) situat... more We consider the phenomena of entanglement of the two interacting self-avoiding walks (SAW) situated in a member of the three-dimensional Sierpinski Gasket (SG) fractal family. We focus our attention to determine number of point contacts between the two SAW paths M, which turns out to be a set of power laws whose characteristics depend predominantly on the interactions between SAW steps. The phase diagrams have been establised and corresponding values of the contact critical exponents phi, associated with the two-path mutual contacts, have been found.
Physical Review E, Jun 24, 2009
Spike packet propagation is modeled in mesoscopic-scale networks, composed of locally and recurre... more Spike packet propagation is modeled in mesoscopic-scale networks, composed of locally and recurrently coupled neural pools, and embedded in a two-dimensional lattice. Site dynamics is governed by three key parameters-pool connectedness probability, synaptic strength Í‘following the steady-state distribution of some realizations of spike-timing-dependent plasticity learning ruleÍ’, and the neuron refractoriness. Formation of spatiotemporal patterns in our model, synfire chains, exhibits critical behavior, with the emerging percolation phase transition controlled by the probability for nonzero synaptic strength value. Applying the finite-size scaling method, we infer the critical probability dependence on synaptic strength and refractoriness and determine the effects of connection topology on the pertaining percolation clusters fractal dimensions. We find that the directed percolation and the pair contact process with diffusion constitute the relevant universality classes of phase transitions observed in a class of mesoscopic-scale network models, which may be related to recently reported data on in vitro cultures.
Percolation approach to formation of synfire chains in two dimensional neural networks
ABSTRACT We consider the propagation of spike packets in two dimensional networks consisting of l... more ABSTRACT We consider the propagation of spike packets in two dimensional networks consisting of locally coupled neural pools. The dynamic attractors of this model, synfire chains, appear for some values of network parameters. The synfire chain formation exhibits behavior, which may be discribed with the percolation phase transition. Using finite-size scaling method, we obtained the critical probabilities and the critical parameter ratio beta/v for different sets of refractoriness and synaptic weights, connecting neighbouring neural pools
Chaos Solitons & Fractals, Aug 1, 2007
We present results of the effects of interpenetration of two interacting self-avoiding walks that... more We present results of the effects of interpenetration of two interacting self-avoiding walks that take place in a member of a three-dimensional Sierpinski Gasket (SG) fractal family. We focus our attention on finding number of point contacts between the two SAW paths, which turns out to be a set of power laws whose characteristics depend predominantly on the given interactions between SAW steps. To establish statistics of the defining model, we apply an exact Renormalization Group Method for the few members Ă°b ÂĽ 2; 3 and 4Ăž of the SG fractal family, as well as a Monte Carlo RG method for 2 6 b 6 25. The phase diagrams have been established and relevant values of the contact critical exponents, associated with the two-path mutual contacts, are determined.
European Physical Journal B, Jun 29, 2010
The widely represented network motif, constituting an inhibitory pair of bursting neurons, is mod... more The widely represented network motif, constituting an inhibitory pair of bursting neurons, is modeled by chaotic Rulkov maps, coupled chemically via symmetrical synapses. By means of phase plane analysis, that involves analytically obtaining the curves guiding the motion of the phase point, we show how the neuron dynamics can be explained in terms of switches between the noninteracting and interacting map. The developed approach provides an insight into the observed time series, highlighting the mechanisms behind the regimes of collective dynamics, including those concerning the emergent phenomena of partial and common oscillation death, hyperpolarization of membrane potential and the prolonged quiescence. The interdependence between the chaotic neuron series takes the form of intermittent synchronization, where the entrainment of membrane potential variables occurs within the sequences of finite duration. The contribution from the overlap of certain block sequences embedding emergent phenomena gives rise to the sudden increase of the parameter characterizing synchronization. We find its onset to follow a power law, that holds with respect to the coupling strength and the stimulation current. It is established how different types of synaptic threshold behavior, controlled by the gain parameter, influence the values of the scaling exponents.
Uniformity control of large area diffraction gratings for augmented reality surface relief waveguide masters
Optical Architectures for Displays and Sensing in Augmented, Virtual, and Mixed Reality (AR, VR, MR) III, 2022
strong coupling. ABSTRACT: Plasmonic excitations are usually attributed to the free electron resp... more strong coupling. ABSTRACT: Plasmonic excitations are usually attributed to the free electron response at visible frequencies in the classic plasmonic metals Au and Ag. However, the vast majority of metals exhibit spectrally localized interband transitions or broad interband transition backgrounds in the energy range of interest for nanoplasmonics. Nevertheless, the interaction of interband transitions with localized plasmons in optical nanoantennas has hitherto received relatively little attention- probably because interband transitions are regarded as highly unwanted due to their 2 strong damping effect on the localized plasmons. However, with an increasing number of metals (beyond Au and Ag) being considered for nanoplasmonic applications such as hydrogen sensing (Pd), UV-SERS (Al) or magnetoplasmonics (Ni, Fe, Co), a deeper conceptual understanding of the interactions between a localized plasmon mode and an interband transition is very important. Here, as a generic example, we ex...
Bubble column design for carbon-dioxide chemical absorption into sodium hydroxide solution
Large area diffraction gratings for augmented reality surface relief waveguide masters
To meet the demand for high quality augmented reality displays with larger field of view, large e... more To meet the demand for high quality augmented reality displays with larger field of view, large eye box and better image quality, large area diffraction gratings are needed. Across the industry different types of surface relief gratings for in-coupling and out-coupling are used in the waveguide designs to achieve the optimum performance of the waveguide. Typical gratings are slanted, blazed, binary and multi-level gratings. NIL Technology offers solutions for all of the above-mentioned types of gratings meeting the demand for high quality and size of in particular the output gratings from the market.
Facta Universitatis. Series: Economics and Organization, 2006
This paper represents a study of the time series of stock market indexes at Belgrade Stock Market... more This paper represents a study of the time series of stock market indexes at Belgrade Stock Market. Statistical analysis of this data is performed and a set of stylized empirical facts is presented. Various statistical properties of stock market indexes returns are described: lack of normality, correlation in the return series, and some non-linear tests. Our description emphasizes properties common to a wide variety of emerging and developing markets. We show statistical properties of Belgrade stock market, which significantly invalidate many of the common statistical approaches used to study financial data sets and examine some of the statistical problems encountered in each case.
Science of Sintering, 2014
Bentonite clays have many applications in industries ranging from construction to cosmetics. Addi... more Bentonite clays have many applications in industries ranging from construction to cosmetics. Addition of polymers can profoundly influence the properties of bentonite suspensions and we now describe the influence of a range of different polymers. Whereas polyvinyl pyrolidone and soy isolate only slightly influenced the pH and the electrical conductivity of bentonite polymers in suspension, Carbopol solution caused decreases in both pH and electrical conductivity. As expected, strong electrolytes like sodium chloride caused big changes in the electrical conductivity of the suspensions. When the temperature of the bentonite suspensions was increased, the pH was almost unchanged, but the electrical conductivity increased. Bentonite treated with polymer suspensions can be used in purifying polluted water; for example, our results suggest that high pH caused by phosphorous salts can be addressed using bentonite modified with Carbopol.
Exact and Monte Carlo study of the two self-avoiding random walks on the three-dimensional Sierpinski lattices
AIP Conference Proceedings, 2007
We consider the phenomena of entanglement of the two interacting self-avoiding walks (SAW) situat... more We consider the phenomena of entanglement of the two interacting self-avoiding walks (SAW) situated in a member of the three-dimensional Sierpinski Gasket (SG) fractal family. We focus our attention to determine number of point contacts between the two SAW paths M, which turns out to be a set of power laws whose characteristics depend predominantly on the interactions between SAW steps. The phase diagrams have been establised and corresponding values of the contact critical exponents phi, associated with the two-path mutual contacts, have been found.
MRS Proceedings, 2012
ABSTRACTThe effect of silver nanoparticles showing localised plasmonic resonances on the efficien... more ABSTRACTThe effect of silver nanoparticles showing localised plasmonic resonances on the efficiency of thin film silicon solar cells is studied. Silver (Ag) nanodiscs were deposited on the surface of silicon cells grown on highly doped silicon substrates, through hole-mask colloidal lithography, which is a low-cost and bottom-up technique. The cells have no back reflector in order to exclusively study the effect of the front surface on their properties. Cells with nanoparticles were compared with both bare silicon cells and cells with an antireflection coating. We optically observe a resonance showing an absorption increase controllable by the disc radius. We also see an increase in efficiency with respect to bare cells, but we see a decrease in efficiency with respect to cells with an antireflection coating due to losses at wavelengths below the plasmon resonance. As the material properties are not notably affected by the particles deposition, the loss mechanism is an important abs...
Plasmonic nanoantennas for SERS, directional light, sensing and strong coupling
2013 15th International Conference on Transparent Optical Networks (ICTON), 2013
ABSTRACT In this paper we discuss several examples of generating directional light emission on a ... more ABSTRACT In this paper we discuss several examples of generating directional light emission on a nanoscale as well as utilization of these results for color routing, sensing and strong coupling applications. Examples include propagating plasmons in metallic nanowires, spontaneous formation of optical phase mismatch in materially asymmetric silver-gold and palladium-gold dimers and exciton-induced transparency in individual silver nanorods covered by a thin layer of J-aggregates.
Percolation approach to formation of synfire chains in two dimensional neural networks
2006 8th Seminar on Neural Network Applications in Electrical Engineering, 2006
ABSTRACT We consider the propagation of spike packets in two dimensional networks consisting of l... more ABSTRACT We consider the propagation of spike packets in two dimensional networks consisting of locally coupled neural pools. The dynamic attractors of this model, synfire chains, appear for some values of network parameters. The synfire chain formation exhibits behavior, which may be discribed with the percolation phase transition. Using finite-size scaling method, we obtained the critical probabilities and the critical parameter ratio beta/v for different sets of refractoriness and synaptic weights, connecting neighbouring neural pools
Physical Review E, 1995
In this work we study the problem of physical (reversible) adsorption of a linear polymer in a go... more In this work we study the problem of physical (reversible) adsorption of a linear polymer in a good solvent in the case when the container of the polymer-solvent system is taken to be the Mandelbrot-Given (MG) model of a percolation cluster and the plane-filling (PF) fractal lattice. We accept the self-avoiding random walk as a model of the linear polymer, and, in addition, we assume that the adsorption energy pertaining to the bonds that lie in the layer next to the adsorbing boundary depends on their directions and is different from the adsorption energy for the bonds that belong to the boundary. Under these conditions we have found, in the case of both fractals (MG and PF), that the crossover exponent P (associated with the number of adsorbed monomers) continuously varies with the parameter that measures the monomer-surface interaction along the bonds that are perpendicular to the adsorbing boundary. We discuss this result and its relevance to the understanding of the validity (violation) of the universality hypothesis in the case of critical phenomena on fractals.
ACS Photonics, 2014
Plasmonic excitations are usually attributed to the free electron response at visible frequencies... more Plasmonic excitations are usually attributed to the free electron response at visible frequencies in the classic plasmonic metals Au and Ag. However, the vast majority of metals exhibit spectrally localized interband transitions or broad interband transition backgrounds in the energy range of interest for nanoplasmonics. Nevertheless, the interaction of interband transitions with localized plasmons in optical nanoantennas has hitherto received relatively little attention-probably because interband transitions are regarded as highly unwanted due to their
physica status solidi (a), 2014
We report on the fabrication, integration, and simulation, both optical and optoelectrical, of tw... more We report on the fabrication, integration, and simulation, both optical and optoelectrical, of two-dimensional photonic nanostructures for advanced light trapping in thin crystalline silicon (c-Si) solar cells. The photonic nanostructures are fabricated by the combination of various lithography (nanoimprint, laser interference, and hole mask colloidal) and etching (dry plasma and wet chemical) techniques. The nanopatterning possibilities thus range from periodic to random corrugations and from inverted nanopyramids to high aspect ratio profiles. Optically, the nanopatterning results in better performance than the standard pyramid texturing, showing a more robust behavior with respect to light incidence angle. Electrically, wet etching results in higher minority carrier lifetimes compared to dry etching. From the integration of the photonic nanostructures into a micron-thin c-Si solar cell certain factors limiting the efficiencies are identified. More precisely: (a) the parasitic absorption is limiting the short circuit current, (b) the conformality of thin-film coatings on the nanopatterned surface is limiting the fill factor, and (c) the material damage from dry etching is limiting the open circuit voltage. From optical simulations, the optimal pattern parameters are identified. From optoelectrical simulations, cell design considerations are discussed, suggesting to position the junction on the opposite side of the nanopattern.
Bulletin of the American Physical Society, 2010
The Journal of Physical Chemistry C, 2010
In this paper, we demonstrate nanoparticle flow control using an optical force in a confined nano... more In this paper, we demonstrate nanoparticle flow control using an optical force in a confined nanospace. Using nanofabrication technologies, all-quartz-glass nanoslit channels with a sudden contraction are developed. Because the nanoslit height is comparable to the nanoparticle diameter, the motion of particles is restricted in the channel height direction, resulting in almost two-dimensional particle motion. The laser irradiates at the entrance of the sudden contraction channel, leading the trapped nanoparticles to form a cluster. As a result, the translocation of nanoparticles into the contraction channel is suppressed. Because the particle translocation restarts when the laser irradiation is stopped, we can control the nanoparticle flow into the contraction channel by switching the trapping and release of particles, realizing an intermittent flow of nanoparticles. Such a particle flow control technique in a confined nanospace is expected to improve the functions of nanofluidic devices by transporting a target material selectively to a desired location in the device.
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Papers by Vladimir Miljkovic