A cross-product statistic is used to demonstrate that spatial interaction models are a special case of a general model of spatial autocorrelation. A series of traditional measures of spatial autocorrelation is shown to have a cross-product form. Several interaction models are shown to have a similar form. A general spatial statistic is developed which indicates that the relationship between the...

background: using spatial analysis tools to determine the spatial patterns of china province-level perinatal mortality and using spatial econometric model to examine the impacts of health care resources and different socio-economic factors on perinatal mortality. methods: the global moran’s i index is used to examine whether the spatial autocorrelation exists in selected regions and moran’s i s...

In this paper, we study an optimal location query based on a road network. Specifically, given a road network containing clients and servers, an optimal location query is to find a location on the road network such that when a new server is set up at this location, a certain cost function computed based on the clients and servers (including the new server) is optimized. Two types of cost functi...

The design of control laws for systems subject to complex state constraints still presents a significant challenge. This paper explores a dynamic programming approach to a specific class of such problems, that of reachability under state constraints. The problems are formulated in terms of nonstandard minmax and maxmin cost functionals, and the corresponding value functions are given in terms o...

We develop a model of multi-candidate electoral competition in a multi-dimensional policy space with strategic voters. We show that when the distribution of voter ideal points is log-concave, there exist pure-strategy subgame perfect equilibria in weakly undominated strategies in which platforms are located in the minmax set. Analytical and numerical results suggest that the size of the minmax ...

Given an acyclic directed graph and two distinct nodes s and t, we consider the problem of finding k disjoint paths from s to t satisfying some objective. We consider four objectives, MinMax, Balanced, MinSum-MinMin, and MinSum-MinMax. We use the algorithm by Perl-Shiloach and labelling and scaling techniques to devise an FPTAS for the first three objectives. For the forth one, we propose a gen...

Introduction: This study aimed to assess a good protocol for the contamination indexes, concentration, spatial analysis, and source identification of toxic metals in top soils. Materials and Methods: In the first step, samples were taken from top soil (30 cm) and the metals were extracted and detected with ICP-AES. In the second step, Enrichment Factor, Geoaccumulation Index, and Contamination...

In 1991, Edelsbrunner and Tan gave an O(n) algorithm for finding the MinMax Length triangulation of a set of points in the plane. In this paper we resolve one of the open problems stated in that paper, by showing that finding a MaxMin Length triangulation is an NPcomplete problem. The proof implies that (unless P=NP), there is no polynomial-time approximation algorithm that can approximate the ...

Autocorrelation functions are a major tool for the understanding of single-cell firing patterns. Short-term peaks in autocorrelation functions have previously been interpreted as a tendency towards bursting activity or elevated probability to emit spikes in a short time-scale. These peaks can actually be a result of the firing of a neuron with a refractory period followed by a period of constan...