title: Number of distinct sites visited by a random walker trapped by an absorbing boundary.
abstract: The number of distinct sites visited by a lattice random walker is a subject of continuing interest in both mathematics and physics. All previous investigations have used the assumption that the lattice is unbounded. An assessment of the amount of tissue interrogated by a photon in reflectance measurements for diagnostic purposes suggests analyzing properties of the average number of distinct sites visited by a random walker trapped by an absorbing plane at time t. We show that for sufficiently large t this number is the same as the average number of distinct sites visited for this time when the surface is not present. A more complete analysis is possible for a random walk on a line terminated by an absorbing point.
authors.affiliation: Center for Information Technology, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: Leonardo
authors.initials: L
authors.lastname: Dagdug
authors.forename: Alexander M
authors.initials: AM
authors.lastname: Berezhkovskii
authors.forename: George H
authors.initials: GH
authors.lastname: Weiss
mesh_terms: D000042:Absorption; D055592:Biophysical Phenomena; D001703:Biophysics; D006801:Humans; D008954:Models, Biological; D008962:Models, Theoretical; D055095:Optics and Photonics; D017785:Photons