In late September, Volkswagen admitted to using software that activated hardware to scrub nitrogen oxide (NOx) emissions during required emissions tests, but not during normal driving. The deception improved the cars’ gas mileage at the cost of emitting between 10 and 40 times the legal limit of NOx, a precursor gas to nitrogen dioxide (NO2), ammonia (NH3), and other gases that cause respiratory problems. In the last few years, newly maturing instruments of several kinds have converged on a single message: diesel exhaust in the real world is far higher than what carmakers advertise and what is permitted by the law in many countries.
Packets of cannabis seeds line the shelves of legal grow shops in Madrid. Many carry labels reporting the percentage of sativa and indica, two types of cannabis. Breeders often label plants that produce a more exciting high as sativa and plants that provide a more mellow feeling as indica, suggesting that cross-breeding tailors that buzz. The conceit is widespread. Botanist Jonathan Page at the University of British Columbia in Vancouver, Canada, says he sees the same at local grow shops.
For reasons that go beyond assessing the quality of the user experience, botanists such as Page are investigating the evolution and present-day diversity of cannabis. To do this, they must confront centuries-old taxonomic questions, including whether cannabis is one species, Cannabis sativa, with several subspecies or varieties, or if it is several distinct species, such as C. sativa, Cannabis indica and Cannabis ruderalis. “It’s complicated taxonomically because of its intimate relationship with humans for long periods of time,” Page says. People have long bred cannabis as a source of fibre, food and oil — as well as for its mind-altering effects (see page S10). As governments relax cannabis laws, commercial growers want more clarity about the chemical properties and capabilities of the herb’s many varieties. In parallel, regulatory bodies trying to establish a legal framework want to be able to classify whether a given type of plant is for fibre (hemp) or recreational or medical use (marijuana).
Palaeontologists who attend the annual International Cave Bear Symposium (ICBS) can usually count on at least one expedition to a bear cave. The meeting allows scientists to report the latest fossil findings of Pleistocene animals such as cave bears and big cats — whose best-preserved samples are often found in caves.
But the 2015 meeting on 10–13 September took place instead near the North Sea coast in the Netherlands, with no caves in sight. Palaeontologist Natasja den Ouden of the Naturalis Biodiversity Center, a museum in Leiden, tells Nature how fossil samples from the North Sea are shedding light on mammals’ movements during the last ice age.
Nobody likes tsunamis, but earthquake engineer Tiziana Rossetto at University College London (TEDx Talk: Engineering against tsunami) is hard at work building one of her own. Don’t worry — it’s not going to destroy your coastline. It’s a scale model designed to help Rossetto and other engineers better understand the precise sequence of events that take place during and after a tsunami. That could help them build better coastal defenses and more resilient buildings — and perhaps even tame the terrible toll of the next big one. Here’s why Rossetto’s ideas matter: Continue reading