2,772 research outputs found
Adsorbed self-avoiding walks subject to a force
We consider a self-avoiding walk model of polymer adsorption where the
adsorbed polymer can be desorbed by the application of a force. In this paper
the force is applied normal to the surface at the last vertex of the walk. We
prove that the appropriate limiting free energy exists where there is an
applied force and a surface potential term, and prove that this free energy is
convex in appropriate variables. We then derive an expression for the limiting
free energy in terms of the free energy without a force and the free energy
with no surface interaction. Finally we show that there is a phase boundary
between the adsorbed phase and the desorbed phase in the presence of a force,
prove some qualitative properties of this boundary and derive bounds on the
location of the boundary
Self-avoiding walks and polygons confined to a square
We prove several rigorous results about the asymptotic behaviour of the
numbers of polygons and self-avoiding walks confined to a square on the square
lattice. Specifically we prove that the dominant asymptotic behaviour of
polygons confined to an LxL square is identical to that of self-avoiding walks
that cross an LxL square from one corner vertex to the opposite corner vertex.
We also prove a result about the subdominant asymptotic behaviour of
self-avoiding walks crossing a square and extend this result to polygons
confined to a square. In addition, we investigate the problems of self-avoiding
walks and polygons in a hypercube in the d-dimensional hypercubic lattice.Comment: Minor errors corrected and some additional results adde
Rapid identification of some Leptospira isolates from cattle by random amplified polymorphic DNA fingerprinting
We compared random amplified polymorphic DNA (RAPD) fingerprinting with cross-absorption agglutination and restriction enzyme analysis for typing bovine leptospires. Using RAPD fingerprinting, we examined a number of Leptospira serovars, namely, hardjo genotypes bovis and prajitno, pomona, balcanica, tarassovi, swajizak, kremastos, australis, and zanoni, which are likely to be isolated from Australian cattle. Each serovar and genotype had a unique RAPD profile. Of 26 field isolates of Leptospira, 23 were identified as hardjo genotype bovis subtype A, 2 were identified as zanoni, and 1 was identified as pomona by RAPD fingerprinting, and their types were confirmed by cross-absorption agglutination and restriction enzyme analysis
Statistics of nested spiral self-avoiding loops: exact results on the square and triangular lattices
The statistics of nested spiral self-avoiding loops, which is closely related
to the partition of integers into decreasing parts, is studied on the square
and triangular lattices.Comment: Old paper, for archiving. 7 pages, 2 figures, epsf, IOP macr
The Tolman-Eichenbaum Machine: Unifying Space and Relational Memory through Generalization in the Hippocampal Formation
The hippocampal-entorhinal system is important for spatial and relational memory tasks. We formally link these domains, provide a mechanistic understanding of the hippocampal role in generalization, and offer unifying principles underlying many entorhinal and hippocampal cell types. We propose medial entorhinal cells form a basis describing structural knowledge, and hippocampal cells link this basis with sensory representations. Adopting these principles, we introduce the Tolman-Eichenbaum machine (TEM). After learning, TEM entorhinal cells display diverse properties resembling apparently bespoke spatial responses, such as grid, band, border, and object-vector cells. TEM hippocampal cells include place and landmark cells that remap between environments. Crucially, TEM also aligns with empirically recorded representations in complex non-spatial tasks. TEM also generates predictions that hippocampal remapping is not random as previously believed; rather, structural knowledge is preserved across environments. We confirm this structural transfer over remapping in simultaneously recorded place and grid cells
Dynamically-Coupled Oscillators -- Cooperative Behavior via Dynamical Interaction --
We propose a theoretical framework to study the cooperative behavior of
dynamically coupled oscillators (DCOs) that possess dynamical interactions.
Then, to understand synchronization phenomena in networks of interneurons which
possess inhibitory interactions, we propose a DCO model with dynamics of
interactions that tend to cause 180-degree phase lags. Employing an approach
developed here, we demonstrate that although our model displays synchronization
at high frequencies, it does not exhibit synchronization at low frequencies
because this dynamical interaction does not cause a phase lag sufficiently
large to cancel the effect of the inhibition. We interpret the disappearance of
synchronization in our model with decreasing frequency as describing the
breakdown of synchronization in the interneuron network of the CA1 area below
the critical frequency of 20 Hz.Comment: 10 pages, 3 figure
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