More than half of the world’s large rivers are fragmented and regulated by dams. The largest and the most biologically and geographically diverse rivers are all affected. This is shown by a global study that is published in this week’s issue of the journal Science.
Behind the study are Christer Nilsson, Cathy Reidy and Mats Dynesius at Umeå University and Carmen Revenga at The Nature Conservancy in the U.S.
Humans have drastically changed many rivers by impoundments and diversions to meet the needs of water, energy and transportation. Such exploitation belongs among the most dramatic, deliberate impacts that humans have had on the natural environment. Many of the ecological effects of dams are relatively well known. Despite this fact, there has so far not been any overview of how this impact is distributed globally.
Karin Wikman | alfa
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Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
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An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
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A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
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