The Encoding-Error Model of Pathway Completion without Vision

We present a model that accounts for errors in short-cutting to complete a triangular pathway by individuals deprived of visual input. The model assumes that systematic error arises from components of navigation concerned with encoding an internal representation of the pathway, rather than the computation of a homeward trajectory or motor output per se. Subjects' tendency to compress the range of actually produced turns and distances, in comparison to the range of correct values, is attributed to regression toward the mean of encoded values during encoding of segments and turns, in the face of uncertainty about the actual values. Individual-subject variations are attributed to differences in the encoding-function parameters, not to variations in the processes themselves. The model provides excellent accounts of data obtained with triangular pathways but fares less well when pathway complexity increases, at which point errors do not appear to be solely attributable to encoding processes. The sources of error identified by the model are likely to play a role in navigation more generally.     

The Brazilian Policy of Sustainable Defence

The history of defence strategy in Brazil has been largely peace-orientated and the armed forces, which have developed independently, have been relatively small. However, recent stability in the economy, consolidation of democratic processes, and cooperation with its neighbours in the region have provided Brazil with the opportunity for new defence thinking which culminated in the 1996 announcement of a National Defence Policy (NDP). In this article the author assesses Brazil's place in the South American strategic theatre and the objectives and main purposes of the NDP. He examines the preventative, cooperative and non-military components of the Policy, which seeks to ensure a balance between state security and social well-being.     

A LONG RUN ECONOMIC EFFECT ANALYSIS OF ALTERNATIVE TRANSPORTATION FACILITY PLANS—REGIONAL AND NATIONAL

Initially we explained the main part of our model which enabled us to estimate and compare the long run and global economic effects of alternative transportation facility plans. Usually the short run effects of this kind of regional economic impact have been analyzed by input-output models, and the long run effects by econometric models. However, in this model, the input-output model and the econometric model were combined so as to enable us to analyze the global and long run economic effects. The interregional trade pattern coefficients and input coefficients change endogenously in each year in this model. It has previously been assumed that the fixedness of interregional trade pattern coefficients and input coefficients are the weakest points in applying the interregional input-output model for long run studies. In our model, on the contrary, variation of these coefficients has central importance. We then showed the results which were obtained from applying this model to a comparison of the long run economic effects of alternative bridge construction plans over the Japan Inland Sea. The results obtained from this demonstrative calculation are reasonable. Thus, we think, this model has sufficient applicability to the comparison of economic effects of alternative plans for nationwide transportation facility improvement. However, the variations of production cost differentials between regions are given exogenously in this model. To make them endogenous, agglomeration economies should be considered more precisely. In that case, the applicability and the precision of this model could be improved.     

ADDITIVE-INTERACTION MODELS OF SPATIAL AGGLOMERATION*

A wide variety of existing models of spatial agglomeration postulate additive-interaction effects among agents. In this paper, a synthesis of such models is achieved by establishing certain mathematical equivalences between them. In particular, it is shown that Rockafellar's conjugacy theory of concave functions yields a symmetric one-to-one correspondence between three classes of existing models, here designated as spatial-accessibility models, endogenous-contact models, and fixed-contact models. These correspondences not only allow the transference of results between models, but also suggest new economic interpretations of each model in terms of its conjugate model. A series of examples are drawn from the literature to illustrate these results.     

A Minimal Representation for Dead-Reckoning Navigation: Updating the Homing Vector

A number of organisms are capable of traveling directly back to the origin of locomotion after following a circuitous outbound path, using dead-reckoning navigation. We describe a minimal representation that could be used for such navigation. It involves keeping track of only the polar coordinates of the origin of locomotion with respect to the observer's current location. An exact solution is provided first, followed by a simplified solution, then a solution involving linearization of trigonometric functions. The paper also examines performance attainable with these solutions and briefly considers ways in which the model might be modified to account for human navigation without reference to landmarks.     

Enclosing Ethnic Minorities and Forests in the Golden Economic Quadrangle

Ethnic minority farmers in the infamous Golden Triangle were first incorporated into the nation states of China, Laos and Thailand, and later into the economic region called the Golden Economic Quadrangle. This article traces policies in each country for minorities, development and the environment, followed by an analysis of agrarian transitions under economic regionalization. Using the framework of powers of exclusion and racialization, our findings show the changes for ethnic minorities who, with the exception of those in the lowlands, face environmental enclosures that dispossess them from lands on which livelihoods are based. Ideological legacies from the Golden Triangle, including ‘backward’ minorities, the fight against drugs, and threats to national security, continue to inform policies and development projects. While some farmers have become entrepreneurs planting cash crops, most face increasing marginalization under deepening regional capitalism.