Frontier malaria is a biological, ecological, and sociodemographic phenomenon operating over time at three spatial scales (micro͞ individual, community, and state and national). We explicate these linkages by integrating data from remote sensing surveys, groundlevel surveys and ethnographic appraisal, focusing on the Machadinho settlement project in Rondô nia, Brazil. Spatially explicit analyses reveal that the early stages of frontier settlement are dominated by environmental risks, consequential to ecosystem transformations that promote larval habitats of Anopheles darlingi. With the advance of forest clearance and the establishment of agriculture, ranching, and urban development, malaria transmission is substantially reduced, and risks of new infection are largely driven by human behavioral factors. Malaria mitigation strategies for frontier settlements require a combination of preventive and curative methods and close collaboration between the health and agricultural sectors. Of fundamental importance is matching the agricultural potential of specific plots to the economic and technical capacities of new migrants. Equally important is providing an effective agricultural extension service.Brazilian Amazon ͉ frontier malaria E conomically and politically driven human migration in the Amazon basin of Brazil over the past century has been accompanied by substantial ecosystem transformation and the promotion of malaria transmission (1-3). Research programs in parasitology, entomology, and epidemiology of vector-borne diseases were established in Brazil in the 1890s (4-6) followed, almost immediately, by translation into malaria mitigation strategies (3, 7). Major eradication and control campaigns in Amazonia, initiated in the 1950s and persisting until 1970 (1), succeeded in reducing the number of malaria cases in the region to Ϸ30,000 (in 1970) (roughly 60% of all cases reported in the country).The modern era of Amazon frontier expansion began during the military government with the introduction of large scale colonization projects focused on agriculture, mineral extraction, and wide-ranging human settlement (8-13). The human population of the Amazon grew from 7.2 million in 1970 to 11 million in 1980 and then to 18.7 million by 1996, accompanied by a dramatic increase in malaria cases (14, 15). As of 1999, there were Ϸ600,000 malaria cases in Brazil, 99.7% of which were concentrated in the legal Amazon. The spatial distribution of these cases was very irregular, and a lack of spatially targeted mitigation strategies resulted in inefficient allocation of resources. In 1986, 60% of all malaria cases in the Amazon were concentrated in 58% of the municipalities, but 70% of the budget for malaria control was spent in municipalities with only 3% of the cases (16).Characterizing malaria risk in the rapidly transforming Amazon ecosystems requires considering biological and ecological phenomena acting at multiple spatial scales, juxtaposed with behavioral and economic conditions. In this regard, we adapt and add precis...

Palavras-chaveredes urbanas, Amazônia, desequilíbrios.Classificação JEL R00. ResumoNas últimas décadas, as redes urbanas que se estendem sobre a Amazônia Legal têm evoluído com o surgimento de cidades médias e com a multiplicação de pequenas aglomerações urbanas, que seguem os traçados das principais rodovias e rios da região. Apesar disso, as redes da Amazônia Legal apresentam diversos aspectos que devem ser estudados sem "euforia", diante de uma série de peculiaridades que merecem ser exploradas com maior profundidade. Mesmo que tenha sido estruturada uma hierarquia urbana aparentemente similar à das demais regiões do país, com centros regionais e locais claramente distinguíveis, os diversos níveis hierárquicos urbanos apresentam dinâmicas demográficas, socioeconômicas e espaciais distintas. A situação de fragilidade das redes urbanas amazônicas está relacionada à criação de impedimentos para os fluxos de pessoas, mercadorias e serviços, cabendo destacar: a) as grandes distâncias que separam as capitais das demais cidades e vilas; b) a carência de infra-estrutura nos setores de transporte e comunicação em grandes porções do território amazônico; c) a grande proporção de população desprovida de recursos materiais e educacionais decisivos no que tange a sua participação ativa nos diversos tipos de fluxos. AbstractIn recent decades, the Amazonian urban networks have been developing with the appearance of medium-sized cities and the multiplication and small urban agglomerations along the main regional roads and rivers. However, Amazonian urban networks have several characteristics that should be studied without "euphoria", because of some peculiarities that deserve to be explored in greater depth. Even though there is an urban hierarchy that seems to be similar to the other regions of the country, with clearly distinguishable regional and local centers, the various urban hierarchical levels have different demographic, spatial and socioeconomic dynamics. The fragility of the Amazonian urban networks is related to the creation of barriers for the flows of people, goods and services, like: a) the great distances that separate the capital cities from the other towns and hamlets; b) the lack of transport and communication infrastructure in large areas of the Amazon territory; c) the large proportion of the population without material and educational resources needed for them to actively participate in the various kinds of flows.

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Resumo AbstractAmong the contemporary metropolis' spatial phenomena, this work highlights the socalled "Implosion" and "Explosion", derived from Henri Lefebvre's work. The implosion is interpreted as a trend to agglomeration in the central areas of metropolis, which means a reoccupying of these areas as privileged spaces. The explosion informs a process of extended urbanization, which indicates the occupation of areas distant from the main centralities. These two trends are related to the called Exopolis, a metropolis interpretation provided by Edward Soja. In the empirical exercise to Belo Horizonte and its metropolitan region, housing market's data were used, and the Fuzzy Clustering Analysis was employed. The results about the implosion hypothesis stresses the heterogeneity of the city's central area, and to explosion, this market provided evidences that it is actually extending itself through the region, either in clusters of housing of workers in the urban fabric, whether in condos for elites. Keywords urbanization; housing market; Belo Horizonte; methods of regional and urban analysis.JEL Codes R00; R2; R3; O18. Implosão e explosão na Exópolis: evidências a partir do mercado imobiliário da RMBH Implosion and explosion in the Exopolis: evidences from the MRBH's real estate market