Searching for rewards in graph-structured spaces

How do people generalize and explore structured spaces? We study human behavior on a multi-armed bandit task, where rewards are influenced by the connectivity structure of a graph. A detailed predictive model comparison shows that a Gaussian Process regression model using a diffusion kernel is able to best describe participant choices, and also predict judgments about expected reward and confidence. This model unifies psychological models of function learning with the Successor Representation used in reinforcement learning, thereby building a bridge between different models of generalization

Calculating the relative entropy of entanglement

We extend Vedral and Plenio's theorem (theorem 3 in Phys. Rev. A 57, 1619) to a more general case, and obtain the relative entropy of entanglement for a class of mixed states, this result can also follow from Rains' theorem 9 in Phys. Rev. A 60, 179.Comment: 2 pages, RevTex, an important reference adde

Hawking Radiation of an Arbitrarily Accelerating Kinnersley Black Hole: Spin-Acceleration Coupling Effect

The Hawking radiation of Weyl neutrinos in an arbitrarily accelerating Kinnersley black hole is investigated by using a method of the generalized tortoise coordinate transformation. Both the location and temperature of the event horizon depend on the time and on the angles. They coincide with previous results, but the thermal radiation spectrum of massless spinor particles displays a kind of spin-acceleration coupling effect.Comment: 8 pages, no figure, revtex 4.0, revisted version with typesetting errors and misprint correcte

Contact Injection into Polymer Light-Emitting Diodes

The variation of current I with voltage V for poly(phenylene vinylene) and other polymer light-emitting diodes has been attributed to carriers tunneling into broad conduction and valence bands. In actuality the electrons and holes tunnel into polaron levels and transport is by hopping among these levels. We show that for small injection the I-V characteristic is determined mainly by the image force, for large injection by space charge effects, but in both cases the strong variation of mobility with field due to disorder plays an important role.Comment: 9 pages, two Postscript figures are aviable upon reques

Using Wittgenstein’s family resemblance principle to learn exemplars

The introduction of the notion of family resemblance represented a major shift in Wittgenstein’s thoughts on the meaning of words, moving away from a belief that words were well defined, to a view that words denoted less well defined categories of meaning. This paper presents the use of the notion of family resemblance in the area of machine learning as an example of the benefits that can accrue from adopting the kind of paradigm shift taken by Wittgenstein. The paper presents a model capable of learning exemplars using the principle of family resemblance and adopting Bayesian networks for a representation of exemplars. An empirical evaluation is presented on three data sets and shows promising results that suggest that previous assumptions about the way we categories need reopening

Quantum pumping in graphene nanoribbons at resonant transmission

Adiabatic quantum charge pumping in graphene nanoribbon double barrier structures with armchair and zigzag edges in the resonant transmission regime is analyzed. Using recursive Green's function method we numerically calculate the pumped charge for pumping contours encircling a resonance. We find that for armchair ribbons the whole resonance line contributes to the pumping of a single electron (ignoring double spin degeneracy) per cycle through the device. The case of zigzag ribbons is more interesting due to zero-conductance resonances. These resonances separate the whole resonance line into several parts, each of which corresponds to the pumping of a single electron through the device. Moreover, in contrast to armchair ribbons, one electron can be pumped from the left lead to the right one or backwards. The current direction depends on the particular part of the resonance line encircled by the pumping contour.Comment: 6 pages, 5 figures. This is an author-created, un-copyedited version of an article accepted for publication in EPL. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The definitive publisher authenticated version is available online at 10.1209/0295-5075/92/4701