Results for "Adib Mehrabi"
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A Note on Approximating 2-TransmittersDec 05 2015A k-transmitter in a simple orthogonal polygon P is a mobile guard that travels back and forth along an orthogonal line segment s inside P. The k-transmitter can see a point p in P if there exists a point q on s such that the line segment pq is normal ... More Unique Set Cover on Unit Disks and Unit SquaresJul 25 2016We study the Unique Set Cover problem on unit disks and unit squares. For a given set $P$ of $n$ points and a set $D$ of $m$ geometric objects both in the plane, the objective of the Unique Set Cover problem is to select a subset $D'\subseteq D$ of objects ... More Algorithms for Brownian first passage time estimationApr 27 2009A class of algorithms in discrete space and continuous time for Brownian first passage time estimation is considered. A simple algorithm is derived that yields exact mean first passage times (MFPT) for linear potentials in one dimension, regardless of ... More NP-hardness of the cluster minimization problem revisitedSep 06 2005The computational complexity of the "cluster minimization problem" is revisited [L. T. Wille and J. Vennik, J. Phys. A 18, L419 (1985)]. It is argued that the original NP-hardness proof does not apply to pairwise potentials of physical interest, such ... More Ergodicity and the Classical Lambda Phi^4 Lattice Field TheoryOct 15 2000In this talk we present some studies in the approach to equilibrium of the classical lambda phi^4 theory on the lattice, giving particular emphasis to its pedagogical usefulness in the context of classical statistical field theory (such as both the analytical ... More Does the Boltzmann principle need a dynamical correction?Apr 27 2002Jun 10 2004In an attempt to derive thermodynamics from classical mechanics, an approximate expression for the equilibrium temperature of a finite system has been derived [M. Bianucci, R. Mannella, B. J. West, and P. Grigolini, Phys. Rev. E 51, 3002 (1995)] which ... More Studying wave optics in the light curve of exoplanet microlensingJul 17 2012Mar 13 2013We study the wave optics features of gravitational microlensing by a binary lens composed of a planet and a parent star. In this system, the source star near the caustic line produces a pair of images in which they can play the role of secondary sources ... More On $r$-Guarding Thin Orthogonal PolygonsApr 25 2016Guarding a polygon with few guards is an old and well-studied problem in computational geometry. Here we consider the following variant: We assume that the polygon is orthogonal and thin in some sense, and we consider a point $p$ to guard a point $q$ ... More Random walk approach to the d-dimensional disordered Lorentz gasNov 12 2007Feb 15 2008A correlated random walk approach to diffusion is applied to the disordered nonoverlapping Lorentz gas. By invoking the Lu-Torquato theory for chord-length distributions in random media [J. Chem. Phys. 98, 6472 (1993)], an analytic expression for the ... More Adiabatic invariance with first integrals of motionMay 11 2002Oct 02 2002The construction of a microthermodynamic formalism for isolated systems based on the concept of adiabatic invariance is an old but seldom appreciated effort in the literature, dating back at least to P. Hertz [Ann. Phys. (Leipzig) 33, 225 (1910)]. An ... More Kink Dynamics in a Topological Phi^4 LatticeApr 26 2001Jun 20 2001It was recently proposed a novel discretization for nonlinear Klein-Gordon field theories in which the resulting lattice preserves the topological (Bogomol'nyi) lower bound on the kink energy and, as a consequence, has no Peierls-Nabarro barrier even ... More Tachyon warm-intermediate inflation in the light of Planck dataApr 19 2016Sep 17 2016We study the main properties of the warm inflationary model based on Barrow's solution for the scale factor of the universe. Within this framework we calculate analytically the basic slow roll parameters for different versions of warm inflation. We test ... More Gauge-QuintessenceOct 03 2015In this work, we introduce a new quintessence model associated with non-Abelian gauge fields, minimally coupled to Einstein gravity. This gauge theory has been originally introduced and studied as an inflationary model, called gauge-flation. Here, however, ... More Sliding k-Transmitters: Hardness and ApproximationJul 25 2016A sliding k-transmitter in an orthogonal polygon P is a mobile guard that travels back and forth along an orthogonal line segment s inside P. It can see a point p in P if the perpendicular from p onto s intersects the boundary of P at most k times. We ... More How clustering dark energy affects matter perturbationsApr 06 2015Aug 01 2015The rate of structure formation in the Universe is different in homogeneous and clustered dark energy models. The degree of dark energy clustering depends on the magnitude of its effective sound speed $c^{2}_{\rm eff}$ and for $c_{\rm eff}=0$ dark energy ... More Constraints on shear and rotation with massive galaxy clustersAug 29 2016A precise determination of the mass function is an important tool to verify cosmological predictions of the $\Lambda$CDM model and to infer more precisely the better model describing the evolution of the Universe. Galaxy clusters have been currently used ... More Optimal Locally Repairable Codes with Improved Update ComplexityJun 30 2016Jul 14 2016For a systematic erasure code, update complexity (UC) is defined as the maximum number of parity blocks needed to be changed when some information blocks are updated. Locally repairable codes (LRCs) have been recently proposed and used in real-world distributed ... More Agegraphic dark energy: growth index and cosmological implicationsAug 31 2016Sep 21 2016We study the main cosmological properties of the agegraphic dark energy model at the expansion and perturbation levels. Initially, using the latest cosmological data we implement a joint likelihood analysis in order to constrain the cosmological parameters. ... More Constraints on shear and rotation with massive galaxy clustersAug 29 2016Nov 14 2016A precise determination of the mass function is an important tool to verify cosmological predictions of the $\Lambda$CDM model and to infer more precisely the better model describing the evolution of the Universe. Galaxy clusters have been currently used ... More Generalized Ghost Dark Energy with Non-Linear InteractionNov 20 2016In this paper we investigate ghost dark energy model in the presence of non-linear interaction between dark energy and dark matter. The functional form of dark energy density in the generalized ghost dark energy (GGDE) model is $\rho_D\equiv f(H, H^2)$ ... More Interferometry for rotating sourcesAug 17 2015Jan 06 2016The two particle interferometry method to determine the size of the emitting source after a heavy ion collision is extended. Following the extension of the method to spherical expansion dynamics, here we extend the method to rotating systems. It is shown ... More 1-Bend RAC Drawings of 1-Planar GraphsAug 30 2016A graph is 1-planar if it has a drawing where each edge is crossed at most once. A drawing is RAC (Right Angle Crossing) if the edges cross only at right angles. The relationships between 1-planar graphs and RAC drawings have been partially studied in ... More Finding Pairwise Intersections Inside a Query RangeFeb 21 2015We study the following problem: preprocess a set O of objects into a data structure that allows us to efficiently report all pairs of objects from O that intersect inside an axis-aligned query range Q. We present data structures of size $O(n({\rm polylog} ... More On Unique Independence Weighted GraphsJul 01 2009An independent set in a graph G is a set of vertices no two of which are joined by an edge. A vertex-weighted graph associates a weight with every vertex in the graph. A vertex-weighted graph G is called a unique independence vertex-weighted graph if ... More Long-lived oscillons from asymmetric bubblesMar 07 2002Sep 11 2002The possibility that extremely long-lived, time-dependent, and localized field configurations (``oscillons'') arise during the collapse of asymmetrical bubbles in 2+1 dimensional phi^4 models is investigated. It is found that oscillons can develop from ... More On Guarding Orthogonal Polygons with Sliding CamerasApr 25 2016A sliding camera inside an orthogonal polygon $P$ is a point guard that travels back and forth along an orthogonal line segment $\gamma$ in $P$. The sliding camera $g$ can see a point $p$ in $P$ if the perpendicular from $p$ onto $\gamma$ is inside $P$. ... More