Toxicology in Cancer Research

Abstract

Toxicology has an important interdisciplinary role to play in the prevention of chemically induced cancer, in the detection of the side effects of anti-cancer drugs and in the reduction or elimination of side-effects. Toxicology is a vital approach to chemotherapeutics, with strong links to basic and clinical research.     

Tests for Patterns in Geographic Variation

We develop tests of whether a pattern of geographic variation departs significantly from random variation over an area. Localities are vertices in a graph whose edges are connections based on criteria of geographic contiguity. Ranked variables are assigned to each locality. Distributions of absolute differences in rank along edges between vertices yield various statistics of edge length that are compared with expectations developed in the paper. Several typical patterns such as a cline, depression, or a crazy-quilt are generated and their behavior characterized by this method. Computational and graphical methods allocate observed patterns to one of several types. The methods are general; three illustrative examples from biology and one from regional studies are furnished.     

Cancer Information A Task of a Cancer Research Centre

Abstract

For many years, the Deutsches Krebsforschungszentrum has been endeavouring to improve communication between the scientists of the Centre and the citizen, who rightly wants to know which results of cancer research are of importance or will become important for him, his family and friends, his children and grandchildren. In view of the 160 000 cancer deaths per year in the Federal Republic of Germany, the pressure felt by scientists engaged in cancer research is great. It is thus all the more important to provide the public with continuous insight into current research programmes, their results and difficulties, and to inform the public of the conditions of research, of the possibilities resulting from the development of new methods, and of the ever more rapid progress in basic research, which, however, is only reflected after years or decades in an improvement of therapy and of diagnostics. To achieve these goals, a telephone 'cancer information service' was installed.     

Loglinear Residual Tests of Moran's I Autocorrelation and their Applications to Kentucky Breast Cancer Data

This article bridges the permutation test of Moran's I to the residuals of a loglinear model under the asymptotic normality assumption. It provides the versions of Moran's I based on Pearson residuals ( I _PR) and deviance residuals ( I _DR) so that they can be used to test for spatial clustering while at the same time account for potential covariates and heterogeneous population sizes. Our simulations showed that both I _PR and I _DR are effective to account for heterogeneous population sizes. The tests based on I _PR and I _DR are applied to a set of log-rate models for early-stage and late-stage breast cancer with socioeconomic and access-to-care data in Kentucky. The results showed that socioeconomic and access-to-care variables can sufficiently explain spatial clustering of early-stage breast carcinomas, but these factors cannot explain that for the late stage. For this reason, we used local spatial association terms and located four late-stage breast cancer clusters that could not be explained. The results also confirmed our expectation that a high screening level would be associated with a high incidence rate of early-stage disease, which in turn would reduce late-stage incidence rates.     

地理信息护航丝路申遗

<正>丝绸之路是重要的线性遗产,其文化发展与地理空间位置分布息息相关。因此,国信司南(北京)地理信息技术有限公司凭借对文物行业的深刻了解、发挥地理信息技术的专业优势,作为丝绸之路申遗的重要技术支持单位,承担了丝绸之路申遗图件所涉及的数据处理、图件编制、地图审核、对外提供等系列工作。丝绸之路申遗路线之长、遗址范围之广,在     

Space-Time Synergetics in Innovation Diffusion: A Nested Network Simulation Approach

The relevance of evolutionary dynamics theories for investigating the development of sociotechnical systems has recently been recognized. In this framework the logistic growth model is considered by many scientists as an extremely appropriate framework that is able to interpret the dynamics of innovation diffusion. Starting from recent results in the literature on technological dynamics, the present paper focuses on backgrounds leading to different shapes of the conventional logistic function. By embedding these motives in the socio-attitudinal context of the system at hand, the present paper tries to give a new interpretation for the rapid/slow “take off” and dynamics of a given innovation in a spatial setting. In particular, a nested logistic dynamic model is developed here, with particular emphasis on the dynamic growth rate of the logistic function expressing—by means of an accessibility cost function—the preference intensity concerning a given innovation for a certain region/country. Finally, various simulation experiments are carried out for the case of both a two-dimensional and a four-dimensional network. The possibility of both stable and unstable diffusion patterns, depending on the parameter values in the nested “attitudinal” dynamic function, is also investigated.     

Properties of Tests for Spatial Dependence in Linear Regression Models

Based on a large number of Monte Carlo simulation experiments on a regular lattice, we compare the properties of Moran's I and Lagrange multiplier tests for spatial dependence, that is, for both spatial error autocorrelation and for a spatially lagged dependent variable. We consider both bias and power of the tests for six sample sizes, ranging from twenty-five to 225 observations, for different structures of the spatial weights matrix, for several underlying error distributions, for misspecified weights matrices, and for the situation where boundary effects are present. The results provide an indication of the sample sizes for which the asymptotic properties of the tests can be considered to hold. They also illustrate the power of the Lagrange multiplier tests to distinguish between substantive spatial dependence (spatial lag) and spatial dependence as a nuisance (error autocorrelation).     

An Assessment of the Space-Time Differential Model for Aggregate Trip Behavior to Planned Suburban Shopping Centers

Aggregate trip behavior to planned suburban shopping centers is studied in terms of changes in trip distance and shopping time within a framework of trip frequency, center scale, and consumer mobility. Such changes are expressed by a second-order differential equation. The assumed shopping strategy is that consumers accelerate the shopping trip cycle by minimizing trip distances. This can be solved to provide theoretical norms to assess against an exploratory data set compiled from 2,810 surveys undertaken in 1980/82 and 1988/89 over a range of centers. The analysis shows a significant relationship between the gravity coefficient and trip frequency. The samples are tested for periodicity using Fourier analysis. The results show that “small” centers are more likely to exhibit periodic behavior. “Large” centers do not follow this hypothesis. Both the gravity coefficient and trip frequency are shown to be quadratic functions of center size. The nonlinearity may be introduced by the agglomeration of shopping opportunities at larger centers. A critical value for “small-” and “large-”center behavior is determined from the minimum points of these distributions. A second equation from classical diffusion analysis is tested for “large” center behavior, where consumers accelerate spatial choice through a time minimization strategy. The results suggest that this strategy occurs at the midrange specialty center during the afternoon of the pre-Christmas rush rather than at large regional centers. The empirical characteristics of the three types of trip behavior are summarized.     

Reconstructing the Space-Time Structure of the HIV/AIDS Epidemic for the Countries of Western Europe

This paper applies a compartmental epidemic modelling system to the estimation of HIV infection transfers between the nations of Western Europe for the period 1973–98. This multiregional model imitates the formation of disease contacts by both local and international travel, where the latter is assumed to have the lower sensitivity to the effects of spatial separation. This system is calibrated in two stages: first, disease parameter sets are found to best fit the timing of recorded AIDS incidence in each nation; and second, these sets are entered into a multiregion setting to identify the travel parameters that support the lags between these series. The outputs include estimates for the first year of HIV incidence in each country and the subsequent pathways of infection transfer that connect these dates. The results indicate the contrasting roles of the southern and northern countries within the continental epidemic and point to national variations in the recent delaying effects on AIDS incidence of drug combination therapies.     

Some Notes on Parametric Significance Tests for Geographically Weighted Regression

The technique of geographically weighted regression (GWR) is used to model spatial 'drift' in linear model coefficients. In this paper we extend the ideas of GWR in a number of ways. First, we introduce a set of analytically derived significance tests allowing a null hypothesis of no spatial parameter drift to be investigated. Second, we discuss 'mixed' GWR models where some parameters are fixed globally but others vary geographically. Again, models of this type may be assessed using significance tests. Finally, we consider a means of deciding the degree of parameter smoothing used in GWR based on the Mallows C_p statistic. To complete the paper, we analyze an example data set based on house prices in Kent in the U.K. using the techniques introduced.     

Spatial Clustering and the Potential for Policy Practice: Experiences from Cluster-building Processes in Sweden

In the last decade, there has been an increased interest in the cluster approach as a regional development tool. Moreover, it has been increasingly acknowledged that TIME (Telekom, IT, Media and Entertainment) industries have come to be of great importance to the economy. This article sets out to examine the use of the cluster approach as an analytical tool as well as a proactive policy tool and an approach based on negotiated and collaborative efforts to manufacture and utilize 'visions' of regional development futures to good effect. Consequently, the intent is not to judge the economic performance of firms in the three case clusters but rather to demonstrate problems and prospects in regional TIME industry cluster-building.     

Clustering and Dispersion of Duopolists in a Linear Market

The locations that two sellers will choose in a linear market has long been of interest. It is well accepted that firms will tend to cluster in the center of the market as long as demand for the product is inelastic and the market area is bounded. It has also been stated that clustering is less strong as demand becomes more elastic, but questions of when this dispersion occurs and what affects it remain to be addressed. This paper further explores clustering in spatial duopoly as elastic demand is allowed. Results indicate that the clustering behavior of sellers is related to the price of the product they sell, the cost to the consumer of acquiring the product, and the elasticity of demand. Locations of sellers in a linear market will lie between the median location and the quartiles as these parameters vary.     

NINE-EYE STONES Cash Used in Ancient Tibet

The Nine-Eye Stone was used as currency inTibet some 4,000 years ago.Although it comesof varied sizes,It assumed one of two shapes-bars and balls.Each has holes which Tibetans call eyesto tie threads.     

Large Sample-Size Distribution of Statistics Used In Testing for Spatial Correlation

Test statistics for testing for spatial correlation in continuous variables have been given by both Moran and Geary and have subsequently been generalized. It has been conjectured for a long time that under the hypothesis of no spatial correlations all these statistics are normally distributed when the sample size is large. This paper proves a very general theorem on the large sample normality of quadratic forms. As corollaries to the theorem the asymptotic normality, under the hypothesis, of all the above-mentioned statistics is established. The necessary conditions are quite unrestrictive. It is also shown, by means of a counter example, that the conditions given in a similar theorem (Cliff and Ord) are inadequate to ensure normality.