Inputs of leaf litter and other organic matter from the catchment exceed autochthonous production and provide an important food ,resource in most streams (WEBSTER & MEYER 1997, ANDERSON & SEDElL 1979). An experimental long-term exclusion of terrestrial litter inputs to a forested headwater stream (WALLACE et al. 1997) provided an opportunity to determine if the food quality of organic matter wo...

Located near the edge of the Pacific coastal plain in the far southeastern corner of Chiapas, Mexico, is the large pre-Columbian ceremonial center known as Izapa. Situated on the terrace of a small stream tributary to the Rio Suchiate, the border river between Mexico and Guatemala, the site consists of more than 130 mounds sprawled over several hectares of lush tropical lowland at the base of t...

Wound closure in the ectoderm of Xenopus early neurulae and chick primitive-streak embryos has been studied by scanning electron microscopy (SEM). Initial gaping of the wound and a cobble-stone appearance of cells peripheral to the wound in both Xenopus and chick confirm that the ectoderm is under lateral tension at these stages. Healing is rapid: in Xenopus embryos wound closure has started wi...

Published evidence of Oldowan stone exploitation generally supports the conclusion that patterns of raw material use were determined by local availability. This is contradicted by the results of systematic studies of raw material availability and use among the earliest known archaeological sites from Gona, Afar, Ethiopia. Artifact assemblages from six Pliocene archaeological sites were compared...

Abstract The poor condition of river diversion channels can prevent mining companies from relinquishing their mine to the government after has ceased. Many regions lack a locally derived template for integrating appropriate geomorphic and hydraulic conditions unmodified into designs help guide post-mining closure activities. Establishing baseline reference criteria catchments restoration effort...

The analysis of formation processes (e.g., degree surface alterations, size ranges, orientation patterns, fabric features, density, spatial etc.) in archaeological sites provide relevant information about the type and intensity sedimentary disturbances. This is particularly important Palaeolithic sites, especially when stratigraphic context suggests certain study follows a multivariate approach...