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Urban tree cover: an ecological perspective   总被引:11,自引:4,他引:7  
Analysis of urban tree cover is generally limited to inventories of tree structure and composition on public lands. This approach provided valuable information for resource management. However, it does not account for all tree cover within an urban landscape, thus providing insufficient information on ecological patterns and processes. We propose evaluating tree cover for an entire urban area that is based on patch dynamics. Treed patches are classified by their origin, structure, and management intensity. A patch approach enables ecologists to evaluate ecological patterns and processes for the entire urban landscape and to examine how social patterns influence these ecological patterns and processes.  相似文献   
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The European region is undergoing dramatic social change. Among other regional and international forces, these changes are rooted in: the collapse of the former Soviet Union; the sudden appearance of a large number of “new” – mostly poor and politically unstable – European nations; and, the emergence of economic trading blocs in North America and Asia. At the same time, the majority of “established” European nations are experiencing sluggish rates of economic growth, moderate to high levels of inflation, high unemployment, escalating demands on public social services, and low fertility in combination with high rates of population aging and immigration from developing countries. Despite the seriousness of the dilemmas confronting the region, European development accomplishments of the past 25 years suggest that the region's leaders already possesses the resources required to solve its complex, social, political, and economic challenges.  相似文献   
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The Collaborative Demonstration Program for Homeless Individuals is providing an opportunity for several community agencies in the United States to explore innovative intervention and treatment strategies to address the needs of homeless people with co-occurring (mental illness and substance abuse) disorders. This cooperative agreement, funded jointly by the Center for Mental Health Services (CMHS) and the Center for Substance Abuse Treatment (CSAT), is a $3 million project supporting programs in various community agencies to develop, document, and evaluate programs for persons who are homeless with co-occurring disorders to be used as models in other communities. The program models include: Assertive Community Treatment, Psychosocial Rehabilitation, Therapeutic Community, and an integrated treatment model. The first phase of the two-phase project funded 16 programs in the U.S. to develop manuals within their primary treatment modalities for homeless people with co-occurring disorders. For Phase II of the project, six of the 16 model programs were competitively selected to demonstrate program impact through formal program evaluation efforts. The data derived from the various projects will be compiled into a compendium of information for state agencies and community service providers throughout the U.S.  相似文献   
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Summary.  In capture–recapture experiments the capture probabilities may depend on individual covariates such as an individual's weight or age. Typically this dependence is modelled through simple parametric functions of the covariates. Here we first demonstrate that misspecification of the model can produce biased estimates and subsequently develop a non-parametric procedure to estimate the functional relationship between the probability of capture and a single covariate. This estimator is then incorporated in a Horvitz–Thompson estimator to estimate the size of the population. The resulting estimators are evaluated in a simulation study and applied to a data set on captures of the Mountain Pygmy Possum.  相似文献   
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Fledgling therapists who graduate from family therapy traning programs will have to navigate the world of managed care. In this article, faculty of University of San Diego share changes in its accredited training program that prepare students for practice in an increasingly multidisciplinary world where health maintenence organizations and other versions of managed care predominate. The paper touches on contextual issues, provides a detailed outline of coursework presenting basic knowledge and skills involved in clinical pracice in a managed care environment, and comments on clinical placements and the challenge of helping the next generation of clinicans "fit" into the future of health care delivery while maintaining their unique identity as family therapists.  相似文献   
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The objective of this study was to teach manual signs through an automated matching-to-sample procedure and to test for the emergence of new conditional relations and imitative behaviors. Seven adults with mild to severe mental retardation participated. Four were also hearing impaired. Relations between manual signs (set A) and pictures (set B) were initially taught, followed by the training of corresponding printed words (set C) and pictures (set B). Further presentations of conditional discriminations tested for the emergence of AC, followed by tests for the emergence of imitative signing behavior (D) in the presence of either pictures (B) or printed words (C). Each stimulus set was comprised of 9 elements. The stimuli were still pictures, printed words, and dynamic presentations of manual signs. A pretest was conducted to determine which signs the participants could make pre-experimentally. Teaching was arranged in a multiple baseline design across 3 groups of 3 words each. The purpose of the present study was to determine whether participants would emit manual signs in expressive signs tests as a result of observation (video modeling) during match-to-sample training in the absence of explicit training. Five of the 7 subjects passed tests of emergence and emitted at least 50% of the signs. Two were hearing impaired with signing experience, and 3 were not hearing impaired and had no signing experience. Thus, observation of video recorded manual signs in a matching-to-sample training procedure was effective at establishing some signs by adults with mental retardation.  相似文献   
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