Evacuation planning in the Auckland Volcanic Field, New Zealand: a spatio-temporal approach for emergency management and transportation network decisions

Auckland is the largest city in New Zealand (pop. 1.5 million) and is situated atop an active monogenetic volcanic field. When volcanic activity next occurs, the most effective means of protecting the people who reside and work in the region will be to evacuate the danger zone prior to the eruption. This study investigates the evacuation demand throughout the Auckland Volcanic Field and the capacity of the transportation network to fulfil such a demand. Diurnal movements of the population are assessed and, due to the seemingly random pattern of eruptions in the past, a non-specific approach is adopted to determine spatial vulnerabilities at a micro-scale (neighbourhoods). We achieve this through the calculation of population-, household- and car-to-exit capacity ratios. Following an analysis of transportation hub functionality and the susceptibility of motorway bridges to a new eruption, modelling using dynamic route and traffic assignment was undertaken to determine various evacuation attributes at a macro-scale and forecast total network clearance times. Evacuation demand was found to be highly correlated to diurnal population movements and neighbourhood boundary types, a trend that was also evident in the evacuation capacity ratio results. Elevated population to evacuation capacity ratios occur during the day in and around the central city, and at night in many of the outlying suburbs. Low-mobility populations generally have better than average access to public transportation. Macro-scale vulnerability was far more contingent upon the destination of evacuees, with favourable results for evacuation within the region as opposed to outside the region. Clearance times for intra-regional evacuation ranged from one to nine hours, whereas those for inter-regional evacuation were found to be so high, that the results were unrealistic. Therefore, we conclude that, from a mobility standpoint, there is considerable merit to intra-regional evacuation

Induction of Endothelial Cell Apoptosis by Solid Tumor Cells

peer reviewedThe mechanisms by which tumor cells extravasate to form metastasis remain controversial. Previous studies performed in vivo and in vitro demonstrate that the contact between tumor cells and the vascular wall impairs endothelium integrity. Here, we investigated the effect of breast adenocarcinoma MCF-7 cells on the apoptosis of human umbilical vein endothelial cells (HUVEC). TUNEL labeling, nuclear morphology, and DNA electrophoresis indicated that MCF-7 cells induced a two- to fourfold increase in HUVEC apoptosis. Caspase-3 activity was significantly enhanced. Neither normal cells tested (mammary epithelial cells, fibroblasts, leukocytes) nor transformed hematopoietic cells tested (HL60, Jurkat) induced HUVEC apoptosis. On the contrary, cells derived from solid tumors (breast adenocarcinoma, MDA-MB-231 and T47D; fibrosarcoma, HT 1080) had an effect similar to that of MCF-7 cells. The induction of apoptosis requires cell-to-cell contact, since it could not be reproduced by media conditioned by MCF-7 cells cultured alone or cocultured with HUVEC. Our results suggest that cells derived from solid tumors may alter the endothelium integrity by inducing endothelial cell apoptosis. On the contrary, normal or malignant leukocytes appear to extravasate by distinct mechanisms and do not damage the endothelium. Our data may lead to a better understanding of the steps involved in tumor cell extravasation

Challenging problems of geospatial visual analytics

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Evacuation planning in the Auckland Volcanic Field, New Zealand: a spatio-temporal approach for emergency management and transportation network decisions

Auckland is the largest city in New Zealand (pop. 1.5 million) and is situated atop an active monogenetic volcanic field. When volcanic activity next occurs, the most effective means of protecting the people who reside and work in the region will be to evacuate the danger zone prior to the eruption. This study investigates the evacuation demand throughout the Auckland Volcanic Field and the capacity of the transportation network to fulfil such a demand. Diurnal movements of the population are assessed and, due to the seemingly random pattern of eruptions in the past, a non-specific approach is adopted to determine spatial vulnerabilities at a micro-scale (neighbourhoods). We achieve this through the calculation of population-, household- and car-to-exit capacity ratios. Following an analysis of transportation hub functionality and the susceptibility of motorway bridges to a new eruption, modelling using dynamic route and traffic assignment was undertaken to determine various evacuation attributes at a macro-scale and forecast total network clearance times. Evacuation demand was found to be highly correlated to diurnal population movements and neighbourhood boundary types, a trend that was also evident in the evacuation capacity ratio results. Elevated population to evacuation capacity ratios occur during the day in and around the central city, and at night in many of the outlying suburbs. Low-mobility populations generally have better than average access to public transportation. Macro-scale vulnerability was far more contingent upon the destination of evacuees, with favourable results for evacuation within the region as opposed to outside the region. Clearance times for intra-regional evacuation ranged from one to nine hours, whereas those for inter-regional evacuation were found to be so high, that the results were unrealistic. Therefore, we conclude that, from a mobility standpoint, there is considerable merit to intra-regional evacuation

Data structures and algorithms to support interactive spatial analysis using dynamic voronoi diagrams

To support the need for interactive spatial analysis, it is often necessary to rethink the data structures and algorithms underpinning applications. This paper describes the development of an interactive environment in which a number of different Voronoi models of space can be manipulated together in real time to: (1) study their behaviour; (2) select appropriate models for specific analysis tasks; and (3) to examine how choice of one model over another will affect the interpretation of data. The paper studies six specific Voronoi diagram variants: the Ordinary Voronoi Diagram, the Farthest-point Voronoi Diagram, the Order-k Voronoi Diagram, the Ordered Order-k Voronoi Diagram, the kth Nearest-point Voronoi Diagram and the Multiplicatively Weighted Voronoi Diagram, and develops algorithms and data structures to store, rebuild and query these variants. From this, a generalised Voronoi data structure is proposed, from which specific Voronoi variants can be reconstructed dynamically as required. Algorithms for diagram reconstruction and for querying neighbourhood (topology or adjacency relations) of generator points and Voronoi regions are presented. An application program, developed on these ideas, is used to generate example results as proof of concept. It may be downloaded from a supporting website

Geographical Information Science observatories, theoretical and methodological transitions

Over the past decades geographical information science has been progressively recognized as a scientific field of its own. Initially starting from a purely engineering perspective, geographical information science is now based on a series of fundamental theories and methods that largely contribute to its recognition in academia. The objective of this paper is to make an argument for more study of the ecosystem of geographical information science through an observational framework, and to examine the processes and abstraction of the different communities that interact with information about geographical spaces. The main idea is to explore and further develop the concept of a geographical information science observatory, the objective of which is to focus not only on geographical information as such, but also and indeed primarily on the users of geographical information, their motivations, and the theoretical, methodological, and technological frameworks with which they develop their information