Dokument-ID Dokumenttyp Verfasser/Autoren Herausgeber Haupttitel Abstract Auflage Verlagsort Verlag Erscheinungsjahr Seitenzahl Schriftenreihe Titel Schriftenreihe Bandzahl ISBN Quelle der Hochschulschrift Konferenzname Quelle:Titel Quelle:Jahrgang Quelle:Heftnummer Quelle:Erste Seite Quelle:Letzte Seite URN DOI Abteilungen
OPUS4-38146 Wissenschaftlicher Artikel Palyulin, Vladimir V.; Metzler, Ralf Speeding up the first-passage for subdiffusion by introducing a finite potential barrier We show that for a subdiffusive continuous time random walk with scale-free waiting time distribution the first-passage dynamics on a finite interval can be optimized by introduction of a piecewise linear potential barrier. Analytical results for the survival probability and first-passage density based on the fractional Fokker-Planck equation are shown to agree well with Monte Carlo simulations results. As an application we discuss an improved design for efficient translocation of gradient copolymers compared to homopolymer translocation in a quasi-equilibrium approximation. Bristol IOP Publ. Ltd. 2014 13 Journal of physics : A, Mathematical and theoretical 47 3 10.1088/1751-8113/47/3/032002 Institut für Physik und Astronomie
OPUS4-36072 Wissenschaftlicher Artikel Palyulin, Vladimir V.; Metzler, Ralf How a finite potential barrier decreases the mean first-passage time We consider the mean first-passage time of a random walker moving in a potential landscape on a finite interval, the starting and end points being at different potentials. From analytical calculations and Monte Carlo simulations we demonstrate that the mean first-passage time for a piecewise linear curve between these two points is minimized by the introduction of a potential barrier. Due to thermal fluctuations, this barrier may be crossed. It turns out that the corresponding expense for this activation is less severe than the gain from an increased slope towards the end point. In particular, the resulting mean first-passage time is shorter than for a linear potential drop between the two points. Bristol IOP Publ. Ltd. 2012 10 Journal of statistical mechanics: theory and experiment 1 10.1088/1742-5468/2012/03/L03001 Institut für Physik und Astronomie
OPUS4-46386 Wissenschaftlicher Artikel Palyulin, Vladimir V.; Mantsevich, Vladimir N.; Klages, Rainer; Metzler, Ralf; Chechkin, Aleksei V. Comparison of pure and combined search strategies for single and multiple targets We address the generic problem of random search for a point-like target on a line. Using the measures of search reliability and efficiency to quantify the random search quality, we compare Brownian search with Levy search based on long-tailed jump length distributions. We then compare these results with a search process combined of two different long-tailed jump length distributions. Moreover, we study the case of multiple targets located by a Levy searcher. New York Springer 2017 16 The European physical journal : B, Condensed matter and complex systems 90 20 37 10.1140/epjb/e2017-80372-4 Institut für Physik und Astronomie
OPUS4-38043 Wissenschaftlicher Artikel Palyulin, Vladimir V.; Chechkin, Aleksei V.; Metzler, Ralf Levy flights do not always optimize random blind search for sparse targets It is generally believed that random search processes based on scale-free, Levy stable jump length distributions (Levy flights) optimize the search for sparse targets. Here we show that this popular search advantage is less universal than commonly assumed. We study the efficiency of a minimalist search model based on Levy flights in the absence and presence of an external drift (underwater current, atmospheric wind, a preference of the walker owing to prior experience, or a general bias in an abstract search space) based on two different optimization criteria with respect to minimal search time and search reliability (cumulative arrival probability). Although Levy flights turn out to be efficient search processes when the target is far from the starting point, or when relative to the starting point the target is upstream, we show that for close targets and for downstream target positioning regular Brownian motion turns out to be the advantageous search strategy. Contrary to claims that Levy flights with a critical exponent alpha = 1 are optimal for the search of sparse targets in different settings, based on our optimization parameters the optimal a may range in the entire interval (1, 2) and especially include Brownian motion as the overall most efficient search strategy. Washington National Acad. of Sciences 2014 6 Proceedings of the National Academy of Sciences of the United States of America 111 8 2931 2936 10.1073/pnas.1320424111 Institut für Physik und Astronomie
OPUS4-37424 Wissenschaftlicher Artikel Palyulin, Vladimir V.; Chechkin, Aleksei V.; Metzler, Ralf Space-fractional Fokker-Planck equation and optimization of random search processes in the presence of an external bias Based on the space-fractional Fokker-Planck equation with a delta-sink term, we study the efficiency of random search processes based on Levy flights with power-law distributed jump lengths in the presence of an external drift, for instance, an underwater current, an airflow, or simply the preference of the searcher based on prior experience. While Levy flights turn out to be efficient search processes when the target is upstream relative to the starting point, in the downstream scenario, regular Brownian motion turns out to be advantageous. This is caused by the occurrence of leapovers of Levy flights, due to which Levy flights typically overshoot a point or small interval. Studying the solution of the fractional Fokker-Planck equation, we establish criteria when the combination of the external stream and the initial distance between the starting point and the target favours Levy flights over the regular Brownian search. Contrary to the common belief that Levy flights with a Levy index alpha = 1 (i.e. Cauchy flights) are optimal for sparse targets, we find that the optimal value for alpha may range in the entire interval (1, 2) and explicitly include Brownian motion as the most efficient search strategy overall. Bristol IOP Publ. Ltd. 2014 32 Journal of statistical mechanics: theory and experiment 10.1088/1742-5468/2014/11/P11031 Institut für Physik und Astronomie
OPUS4-44938 Wissenschaftlicher Artikel Palyulin, Vladimir V.; Chechkin, Aleksei V.; Klages, Rainer; Metzler, Ralf Search reliability and search efficiency of combined Levy-Brownian motion: long relocations mingled with thorough local exploration A combined dynamics consisting of Brownian motion and Levy flights is exhibited by a variety of biological systems performing search processes. Assessing the search reliability of ever locating the target and the search efficiency of doing so economically of such dynamics thus poses an important problem. Here we model this dynamics by a one-dimensional fractional Fokker-Planck equation combining unbiased Brownian motion and Levy flights. By solving this equation both analytically and numerically we show that the superposition of recurrent Brownian motion and Levy flights with stable exponent alpha < 1, by itself implying zero probability of hitting a point on a line, leads to transient motion with finite probability of hitting any point on the line. We present results for the exact dependence of the values of both the search reliability and the search efficiency on the distance between the starting and target positions as well as the choice of the scaling exponent a of the Levy flight component. Bristol IOP Publ. Ltd. 2016 21 Journal of physics : A, Mathematical and theoretical 49 2189 2193 10.1088/1751-8113/49/39/394002 Institut für Physik und Astronomie
OPUS4-7628 misc Palyulin, Vladimir V.; Ala-Nissila, Tapio; Metzler, Ralf Polymer translocation: the first two decades and the recent diversification Probably no other field of statistical physics at the borderline of soft matter and biological physics has caused such a flurry of papers as polymer translocation since the 1994 landmark paper by Bezrukov, Vodyanoy, and Parsegian and the study of Kasianowicz in 1996. Experiments, simulations, and theoretical approaches are still contributing novel insights to date, while no universal consensus on the statistical understanding of polymer translocation has been reached. We here collect the published results, in particular, the famous-infamous debate on the scaling exponents governing the translocation process. We put these results into perspective and discuss where the field is going. In particular, we argue that the phenomenon of polymer translocation is non-universal and highly sensitive to the exact specifications of the models and experiments used towards its analysis. 2014 21 9016 9037 urn:nbn:de:kobv:517-opus4-76287 Institut für Physik und Astronomie
OPUS4-7626 Wissenschaftlicher Artikel Palyulin, Vladimir V.; Ala-Nissila, Tapio; Metzler, Ralf Metzler, Ralf Polymer translocation: the first two decades and the recent diversification Probably no other field of statistical physics at the borderline of soft matter and biological physics has caused such a flurry of papers as polymer translocation since the 1994 landmark paper by Bezrukov, Vodyanoy, and Parsegian and the study of Kasianowicz in 1996. Experiments, simulations, and theoretical approaches are still contributing novel insights to date, while no universal consensus on the statistical understanding of polymer translocation has been reached. We here collect the published results, in particular, the famous-infamous debate on the scaling exponents governing the translocation process. We put these results into perspective and discuss where the field is going. In particular, we argue that the phenomenon of polymer translocation is non-universal and highly sensitive to the exact specifications of the models and experiments used towards its analysis. Cambridge the Royal Society of Chemistry 2014 22 Soft matter 45 10 9016 9037 urn:nbn:de:kobv:517-opus4-76266 Institut für Physik und Astronomie
OPUS4-38210 Review Palyulin, Vladimir V.; Ala-Nissila, Tapio; Metzler, Ralf Polymer translocation: the first two decades and the recent diversification Probably no other field of statistical physics at the borderline of soft matter and biological physics has caused such a flurry of papers as polymer translocation since the 1994 landmark paper by Bezrukov, Vodyanoy, and Parsegian and the study of Kasianowicz in 1996. Experiments, simulations, and theoretical approaches are still contributing novel insights to date, while no universal consensus on the statistical understanding of polymer translocation has been reached. We here collect the published results, in particular, the famous-infamous debate on the scaling exponents governing the translocation process. We put these results into perspective and discuss where the field is going. In particular, we argue that the phenomenon of polymer translocation is non-universal and highly sensitive to the exact specifications of the models and experiments used towards its analysis. Cambridge Royal Society of Chemistry 2014 22 Soft matter 10 45 9016 9037 10.1039/c4sm01819b Institut für Physik und Astronomie
OPUS4-43983 misc Palyulin, Vladimir V; Blackburn, George; Lomholt, Michael A; Watkins, Nicholas W; Metzler, Ralf; Klages, Rainer; Chechkin, Aleksei V. First passage and first hitting times of Lévy flights and Lévy walks For both Lévy flight and Lévy walk search processes we analyse the full distribution of first-passage and first-hitting (or first-arrival) times. These are, respectively, the times when the particle moves across a point at some given distance from its initial position for the first time, or when it lands at a given point for the first time. For Lévy motions with their propensity for long relocation events and thus the possibility to jump across a given point in space without actually hitting it ('leapovers'), these two definitions lead to significantly different results. We study the first-passage and first-hitting time distributions as functions of the Lévy stable index, highlighting the different behaviour for the cases when the first absolute moment of the jump length distribution is finite or infinite. In particular we examine the limits of short and long times. Our results will find their application in the mathematical modelling of random search processes as well as computer algorithms. 2019 25 Postprints der Universität Potsdam Mathematisch-Naturwissenschaftliche Reihe 785 urn:nbn:de:kobv:517-opus4-439832 10.25932/publishup-43983 Institut für Physik und Astronomie