The (k,n)-perfect shuffle, a generalisation of the 2-way perfect shuffle, cuts a deck of kn cards into k equal size decks and interleaves them perfectly with the first card of the last deck at the top, the first card of the second-to-last deck as the second card, and so on. It is formally defined to be the permutation ρk,n : i→ ki (mod kn + 1), i ∈ {1,2, . . . ,kn}. We uncover the cycle structu...

When a rat crosses the place field of a hippocampal pyramidal cell, this cell typically fires a series of spikes. Spike phases, measured with respect to theta oscillations of the local field potential, on average decrease as a function of the spatial distance traveled. This relation between phase and position of spikes might be a neural basis for encoding and is called phase precession. The deg...

The ability to associate some stimuli while differentiating between others is an essential characteristic of biological memory. Theoretical models identify memories as attractors of neural network activity, with learning based on Hebb-like synaptic modifications. Our analysis shows that when network inputs are correlated, this mechanism results in overassociations, even up to several memories "...

One of the classic data structures for storing point sets in R is the priority search tree, introduced by McCreight in 1985. We show that this data structure can be made in-place, i.e., it can be stored in an array such that each entry only stores one point of the point set. We show that the standard query operations can be answered within the same time bounds as for the original priority searc...

A number of computational models of hippocampal place cells incorporate attractor neural network architecture to simulate key findings in the place cell literature, including the properties of pattern completion, firing in the absence of visual input, and nonlinear responses to environmental manipulations. To test for evidence of attractor dynamics, ensembles of place cells were recorded using ...

Omni-directional locomotion systems are yet of little advantage in virtual environments (VEs) with limited large display system, where users may experience visualless situations when they move in a direction that is not covered by the large screen. This paper presents a new omni-directional locomotion interface based on step-inplace movement and a smart-turntable system to impart users with the...

The firing of hippocampal principal cells in freely running rats exhibits a progressive phase retardation as the animal passes through a cell's "place" field. This "phase precession" is more complex than a simple linear shift of phase with position. In the present paper, phase precession is quantitatively analyzed by fitting multiple (1-3) normal probability density functions to the phase versu...

Currently there is limited evidence linking age-friendly characteristics to outcomes in elders. Using a representative sample of 1,376 adults aged 60 and older living in Detroit, this study examined the association between age-friendly social and physical environmental characteristics and the expectation to age in place, and the potential differences between low- and higher-income elders. Based...