Algebraic approach to spatial reasoning

Abstract

A simple, exemplary system is described that performs reasoning about the spatial relationships between members of a set of spatial objects. The main problem of interest is to make sound and complete inferences about the set of all spatial relationships that hold between the objects, given prior information about a subset of the relationships. The spatial inferences are formalized within the framework of relation algebra and procedurally implemented in terms of constraint satisfaction procedures. Although the approach is general, the particular example employs a new ‘complete’ set of topological relationships that have been published elsewhere. In particular, a relation algebra for these topological relations is developed and a computational implementation of this algebra is described. Systems with such reasoning capabilities have many applications in geographical analysis and could be usefully incorporated into geographical information systems and related systems.     

Environmental decision support system project: an exploration of alternative architectures for geographical information systems

Abstract

Recent changes in information technology offer the opportunity to explore alternative architectures for geographical information systems (GIS) which might better support advanced applications. This paper describes the architecture and implementation of the environmental decision support system (EDSS), a prototype GIS tool kit. The architecture is based on a simple yet powerful systems model using only data collections, views and operations as the basic entity types. The design of the user interface, data management and data analysis within the model are outlined, with particular emphasis on the advanced facilities for which implementation is simplified by the architecture. A prototype applications system, BANKSIA, is also described.     

Determinism within human–environment research and the rediscovery of environmental causation

The popularity of the work Guns, germs and steel (GGS) has served to bring the question of human–environment connections once again to the forefront of popular thought. We assert that the recent success of GGS represents both a persistence of environmental determinist logic and a contemporary trend that privileges the environment as the primary influence on human–environment relationships. The historical development of the human–environment field is reviewed from the cultural and political ecology (CAPE) perspective, with particular attention to illustrating the varying emphasis between humans and their environment. GGS is situated within this developing field through a critical analysis of the arguments and methods forwarded by Jared Diamond. The book is found to mirror earlier environmental determinism by failing to take into account many of the advances in human–environmental thought since the early twentieth century. Its popular success suggests the pitfalls of failures to acknowledge the complex, intertwined and indivisible relationship that exists among humans and their environment. Furthermore, there is evidence that the environmental determinism espoused in GGS has caught the attention of international development policymakers potentially influencing future outlays of aid and assistance to the developing world. These conclusions raise cautionary flags against repeating past theoretical mistakes by accepting simplistic, causal explanations based largely on a deterministic conception of the natural environment.     

A STATISTICAL PROCEDURE TO EVALUATE CLEAN-UP STANDARDS

The object of this paper is to develop a suitable statistical procedure to evaluate clean-up standards athazardous waste sites.Under the assumptions that contaminant masses at a site follow a gammadistribution and that the data from the pre-remediation baseline sample as well as from the interim orfinal sample taken after a certain period of operation are both distributed as gamma with the same shapeparameter but different scale parameters,we derive a uniformly most powerful unbiased test of thehypothesis that a specified percentage of contaminant mass has been reduced.A large-sampleapproximation of the exact test procedure and a comparison with the likelihood ratio test are provided.     

Late Pleistocene and Holocene glacial history of James Ross Island, Antarctic Peninsula

Studies of Quaternary glacial stratigraphy and morphology around the Antarctic Peninsula have shown that James Ross Island in the western Weddell Sea probably has the best occurrences of stratigraphic sections with dateable material in the region. The stratigraphy includes sections with indefinite radiocarbon age, and three separate aminozones can be recognized. Except for indications of an early deglaciation around c . 10,000 BP, the field evidence from northern James Ross Island suggests a glacial readvance around 7000 BP. It is concluded that the readvance reflects the combined effects of eustatic sea level rise and Holocene warming, leading to increased precipitation and a positive mass balance. The most recent large-scale deglaciation in the area took place around 6000–5000 BP. This confirms the evidence from lake sediments and moss banks in other parts of the Antarctic Peninsula region, which shows that, in most cases, the initiation of organic deposition took place after c . 6000 BP. The literature on the Holocene glacial and environmental history of the region is reviewed in light of the new field evidence.     

What status for the Quaternary?

The status of the Quaternary, long regarded as a geological period effectively coincident with the main climatic deterioration of the current Ice Age, has recently been questioned as a formal stratigraphic unit. We argue here that it should be retained as a formal period of geological time. Furthermore, we consider that its beginning should be placed at the Gauss-Matuyama magnetic chron boundary at about 2.6 Ma, rather than at its current position at about 1.8 Ma. The Quaternary would be formally subdivided into the Pleistocene and Holocene epochs. The global chronostratigraphical correlation table proposed is enclosed at the back of this issue.     

The Rare Earth Elements and Uranium in Garnets from the Beinn an Dubhaich Aureole, Skye, Scotland, UK: Constraints on Processes in a Dynamic Hydrothermal System

Garnets from skarns in the Beinn an Dubhaich granite aureole,Isle of Skye, Scotland, have a large range of concentrationsof uranium (0·2–358 ppm) and the rare earth elements(REE) (23–4724 ppm). Variations in these concentrationscorrelate with major element zonation within the garnets, andwith changes in the shape of REE patterns. Typical patternsin most garnets display light REE (LREE) enrichment, flat heavyREE (HREE) distribution and a negative Eu anomaly. These patternsare interpreted to represent equilibrium trace element exchangebetween pre-existing pyroxene, hydrothermal fluid and calcicgarnets. Iron-rich zones are characterized by positive Eu anomaliesand an increase in the abundance of the LREE relative to theHREE. These patterns are interpreted as resulting from changesin REE speciation related to the introduction of externallybuffered fluid to the skarn system. Relatively Fe-poor zonesshow strongly HREE-enriched patterns with negative Eu anomaliesand in some instances depletions in Y relative to Ho and Dy,which are interpreted as resulting from surface sorption ofthe REE during rapid, disequilibrium garnet growth. Strong correlationsbetween U abundance and the REE patterns indicate that the sameprocesses have affected U distribution. Both types of patterncan be modified by the effects of closed-system crystallizationon REE abundance in the fluid, and changes in fluid major elementchemistry. KEY WORDS: fractionation; garnet; hydrothermal; rare earth elements; skarn     

Hf Isotope Systematics of Kimberlites and their Megacrysts: New Constraints on their Source Regions

Kimberlites from Southern Africa, along with their low-Cr megacrysts,have unusual Hf–Nd isotopic characteristics. Group I andTransitional kimberlites define arrays trending oblique to,and well below, the Nd–Hf isotope ‘mantle array’,defined by oceanic basalts, i.e. they have negative     

Sustainable Development: The Economic and Environmental Case for Policy Reform

Abstract. Acceptance of the concept of sustainable development as a long term goal has shifted the nature of the debate about the environment and its relation to development. Previously, emphasis was on the adverse effects of economic development on the environment. It is now argued that a degraded and deteriorating environment is a threat to economic development. However, if the promise of sustainability is to be fully explored some fundamental changes must be made. The most important changes concern: first, the way ecological factors are integrated into economic decision making; second, the design of domestic policies; third, the emergence of environmental change as a force in international relations; and, fourth, the need to restructure the international economy and global political arrangements. Canada and New Zealand provide examples of efforts to tackle these issues, to halt environmental destruction and resource depletion, and to meet global development needs.