Particle acceleration on megaparsec scales in a merging galaxy cluster

Galaxy clusters form through a sequence of mergers of smaller galaxy clusters and groups. Models of diffusive shock acceleration suggest that in shocks that occur during cluster mergers, particles are accelerated to relativistic energies, similar to conditions within supernova remnants. In the presence of magnetic fields, these particles emit synchrotron radiation and may form so-called radio relics. We detected a radio relic that displays highly aligned magnetic fields, a strong spectral index gradient, and a narrow relic width, giving a measure of the magnetic field in an unexplored site of the universe. Our observations show that diffusive shock acceleration also operates on scales much larger than in supernova remnants and that shocks in galaxy clusters are capable of producing extremely energetic cosmic rays.     

Sustainability aspects of commercial medicinal plant harvesting in Suriname

The commercial harvest of herbal medicine to meet the growing urban demand has become an environmentally destructive activity in many countries. Non-sustainable harvesting not only threatens the survival of medicinal plant species, but also the people that depend on them. In Suriname, the urbanization of Maroons has created a lively trade in medicinal plants, but little is known on the ecological effects of this trade. To find out whether this commercial harvest was a destructive activity, we carried out a market survey and followed commercial extractors into the forest to look for signs of overharvesting. We analyzed our results from three perspectives: the market, the harvesters and the post-harvest survival of the particular plants. Of the 249 commercial species, less than half was harvested exclusively from the wild. Most extraction took place in secondary forest or man-made vegetation close to the capital. Leaves were the main product. Apart from a few primary forest-based species (e.g., Begonia glabra), we found little evidence for declining resources. Maroons were actively cultivating and managing wild plants. Our three-way analysis enabled us to distinguish between species without sustainability problems (abundant, domesticated, cultivated, limited market value, disturbance species or surviving harvest) and species with conservation priorities. This study illustrates that the increased commercialization of medicinal plants due to urbanization does not invariably lead to declining resources and species loss. With its low population density and market dominated by disturbance species, Suriname offers good possibilities for sustainable medicinal plant extraction.