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Spatial variation in plant diversity has been attributed to heterogeneity in resource availability for many ecosystems. However, urbanization has resulted in entire landscapes that are now occupied by plant communities wholly created by humans, in which diversity may reflect social, economic, and cultural influences in addition to those recognized by(More)
Rapid urbanization has become an area of crucial concern in conservation owing to the radical changes in habitat structure and loss of species engendered by urban and suburban development. Here, we draw on recent mechanistic ecological studies to argue that, in addition to altered habitat structure, three major processes contribute to the patterns of(More)
A detailed fixed nitrogen (N) mass balance was constructed for the Central Arizona–Phoenix (CAP) ecosystem. Input of fixed N input to the ecosystem was 98 Gg y Ϫ1. Of this, humans deliberately imported or mediated the fixation of 51 Gg N y Ϫ1 ; combustion processes added another 36 Gg y Ϫ1. Fixation by desert plants, wet deposition, and surface water input(More)
BACKGROUND Spontaneous supratentorial intracerebral haemorrhage accounts for 20% of all stroke-related sudden neurological deficits, has the highest morbidity and mortality of all stroke, and the role of surgery remains controversial. We undertook a prospective randomised trial to compare early surgery with initial conservative treatment for patients with(More)
Urban ecosystems are profoundly modified by human activities and thereby provide a unique ''nat-ural laboratory'' to study potential ecosystem responses to anthropogenic environmental changes. Because urban environments are now affected by urban heat islands, carbon dioxide domes, and high-level nitrogen deposition, to some extent they portend the future of(More)
PURPOSE To assess whether chemotherapy that includes drugs that cross the blood-brain barrier improves survival in primary CNS non-Hodgkin's lymphoma (PCNSL) when combined with radiotherapy. PATIENTS AND METHODS Thirty-four patients, with no evidence of human immunodeficiency virus type 1 (HIV-1) infection, were treated with the related chemotherapy(More)