BACKGROUND Native Amazonian populations managed forest resources in numerous ways, often creating oligarchic forests dominated by useful trees. The scale and spatial distribution of forest modification beyond pre-Columbian settlements is still unknown, although recent studies propose that human impact away from rivers was minimal. We tested the hypothesis that past human management of the usefu...

1. Society benefits immeasurably from rivers. Yet over the past century, humans have changed rivers dramatically, threatening river health. As a result, societal well-being is also threatened because goods and services critical to human society are being depleted. 2. `Health' Ð shorthand for good condition (e.g. healthy economy, healthy communities) Ð is grounded in science yet speaks to citize...

Ecdyonurus dispar gratificus ssp. nov. is reported from several small streams and rivers within the Donetsk Ridge (East of Ukraine). The new subspecies is described and illustrated on larvae and reared adults of both sexes. SEM photographs of the egg structures are presented. Critical diagnostic characters distinguishing the new subspecies from other representatives of the subgenus Ecdyonurus E...

It was found that the build-up of simuliid numbers subsequent to the construction of dams in the Vaal and Orange Rivers could be successfully prevented by periodic, artificially controlled reductions in the water-levels in these rivers.

the tajan river is one of the most important rivers in the north of iran. it seems that in respect of its meander design and pattern, passing over the block's fault and deviations along its way, it's influenced with active neotectonically movements in the region. although being meander in rivers, in the level of a flood water field with very low gradient, isn't unexpected but exi...

Robert J. Davies-Colley National Institute of Water and Atmospheric Research (NIWA), PO Box 11-115, Hillcrest, Hamilton, New Zealand. ABSTRACT: River water quality is important to uses and values within rivers and also in water bodies downstream. Water quality here encompasses: the physico-chemical attributes important to aquatic life and that vary diurnally (e.g. dissolved oxygen, temperature)...

Using purely physical arguments, it is claimed that for ID Schrödinger operators with complex PT-symmetric potentials having a purely real, attractive potential well and a purely imaginary repulsive part, bound state eigenvalues will be discrete and real. This has been illustrated with several potentials possessing similar properties.