The neural coding of spatial location for memory function may involve grid cells in the medial entorhinal cortex, but the mechanism of generating the spatial responses of grid cells remains unclear. This review describes some current theories and experimental data concerning the role of sensory input in generating the regular spatial firing patterns of grid cells, and changes in grid cell firin...

Speech production can be described in multiple coordinate frames: articulatory configurations, gestural tasks, and acoustic patterns. Examination of the achievement of retroflex stops and liquids in Tamil suggests that we must consider separately the gestural task of apical post-alveolar constriction and the articulatory maneuver to achieve the task. The maneuver of the tongue during retroflex ...

Recently Frankel [1] and Young [3, 4] have developed a method of successive overrelaxation for the solution of the difference equation analogue of the Dirichlet problem for a linear elliptic partial differential equation. The purpose of this note is to present a simple asymptotic theory of the overrelaxation process which depends on the assumption that the mesh size h approaches zero, but which...

In this paper we introduce an abstract data type for the distributed representation and eecient handling of sparse grids on parallel architectures. The new data layout, implemented by means of the PVM message passing library, provides partitioning and dynamic load balancing transparent to the application making use of it. This enables parallelization of sequential partial diierential equations ...

Training: intractable likelihood likelihood needed for MCMC; grid MRF intractable due to global normalization. Solution: pseudo-likelihood approximation, locally normalized: p(y|f) = ∏P p=1 p(yp|yp+1 . . . yP , f) ≈ ∏P p=1 p(yp|neighbours(p), f) Prediction: intractable marginals Pixel-wise MAP intractable in grid MRF. Solution: Obtain approximate marginals using treereweighted belief propagatio...

Critical points of a scalar function (minima, saddle points and maxima) are important features to characterize large scalar datasets, like topographic data. But the acquisition of such datasets introduces noise in the values. Many critical points are caused by the noise, so there is a need to delete these extra critical points. The Morse-Smale complex is a mathematical object which is studied i...

We present an asymptotic formula for the number of line segments connecting q + 1 points of an n × n square grid, and a sharper formula, assuming the Riemann hypothesis. We also present asymptotic formulas for the number of lines through at least q points and, respectively, through exactly q points of the grid. The well-known case q = 2 is so generalized.

This paper presents methods for analyzing and manipulating unevenly spaced time series without a transformation to equally spaced data. Processing and analyzing such data in its unaltered form avoids the biases and information loss caused by resampling. Care is taken to develop a framework consistent with a traditional analysis of equally spaced data, as in Brockwell and Davis (1991), Hamilton ...

A significant volume of research demonstrates that out-of-school learning activities enhance student development in terms of cognitive, affective and social outcomes. However, there is also evidence that the opportunity to engage in these activities has been severely reduced in recent years. This paper explores the extent to which the provision of such opportunities is unevenly distributed— spa...