Geomorphology Humans and livestock seek refuge together after rains deluged Bangladesh. Torrential rains will become more common as the climate changes. Very heavy rainfalls that are rare in our current climate are likely to become more common as precipitation patterns shift in a warming world. Scientists have projected that climate change will increase average global precipitation, because in a warmer atmosphere the air has higher concentrations of water vapour. For the same reason, the heaviest downpours of the future might be even more drenching than the most intense rains of today.
Gunnar Myhre at the Center for International Climate Research in Oslo and his colleagues investigated whether global warming might also change the frequency of extreme precipitation events. Using historical weather records and climate-model simulations, the team found that the heaviest precipitation events of today will probably occur almost twice as often with each further degree of global warming.
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The total amount of precipitation from extreme weather events is therefore also likely to roughly double per degree, with potentially severe impacts on societies. Huge numbers of blue mussels pictured in France have died from a transmissible cancer that originated in a related species. Credit: Alamy. A contagious cancer affecting shellfish has crossed oceans — and species barriers — to threaten mussels in Europe and South America.
Transmissible tumours are rogue cell lineages that spread between individuals. Such tumours have been found in Tasmanian devils Sarcophilus harrisii and bivalves, including the bay mussel Mytilus trossulus , which lives in the Northern Hemisphere. Since , a related species, the blue mussel Mytilus edulis , has experienced mass die-offs in France. These events show signs of being caused by a transmissible tumour. A team led by Michael Metzger at the Pacific Northwest Research Institute in Seattle, Washington, sequenced DNA found in blue mussels from France and the Netherlands, and identified tumour cells with genetic markers characteristic of bay mussels.
The researchers also found that Chilean mussels Mytilus chilensis , a species from Argentina and Chile, had tumours that were almost genetically identical to those afflicting the European blue mussels. The tumours originated in a single bay mussel and then spread to the South American and European mussel species — probably via international shipping vessels, the researchers suggest.source
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When the aroma of fresh coffee hits your nose, odour receptors send signals to a brain region called the olfactory bulb, which then transfers this information to other areas of the brain. Scientists had thought that people without olfactory bulbs could not detect odours. But as Tali Weiss and Noam Sobel at the Weizmann Institute of Science in Rehovot, Israel, and their colleagues reviewed brain scans of healthy, left-handed participants for a smell study, they found two women who seemed to lack olfactory bulbs but could still smell. The team then analysed brain-scan data from more than 1, people, including women, and found that roughly 0.
Neuron Analysis of a gas cloud from this period contradicts current thinking about the first stars. One of the oldest clouds of intergalactic gas found so far has a surprisingly contemporary composition, suggesting that the first stars to form after the Big Bang lived and died more quickly than thought. Early in the history of the Universe, gas clouds birthed the first galaxies and stars.
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But the details of this process remain mysterious. Spectral analysis showed that the amounts of carbon and other elements in the cloud are much lower than those found in modern stars. This suggests that the cloud is made up of material from the early Universe. But the ratios of these elements do not match the ratios that would be expected if the cloud contained remnants of the first generation of stars.
Flames flicker in the hills above Goleta, California. Invasion by non-native grasses sharply increases fire risk in a variety of ecosystems across the continental United States, from deciduous forest in the east to the deserts of the southwest. Emily Fusco at the University of Massachusetts, Amherst, and her colleagues used government records, satellite fire data and computer models to analyse the impact of 12 species of non-native grasses on fire trends in 29 US ecological regions. The researchers then compared these patterns in invaded and uninvaded landscapes.
The results showed that fire had burned more of a habitat riddled with one of eight weed species than the same type of habitat without the invader.
For example, flames had torched 2. Of the eight fire-promoting weeds, six increased fire frequency in the ecosystems that they had invaded. The authors suggest that the presence of invasive grasses should be considered more prominently in future land-management plans. Natl Acad. USA Researchers have modelled the motions of the fault involved in the quake. The great Cascadia earthquake of shook the coasts of what are now British Columbia, Washington and Oregon so violently that afterwards, entire forests stood below sea level.
Now scientists have found similarities between the Cascadia event and other huge quakes that help to illuminate the seismic danger facing the region. Erin Wirth and Arthur Frankel at the US Geological Survey in Seattle, Washington, developed a model to describe ground movement during the Cascadia quake, which is estimated to have been a magnitude 9 — as large as a earthquake in Tohoku, Japan that killed roughly 20, people. The most accurate scenario exhibited features of the Japanese quake and a magnitude During both, parts of the Earth deep within the fault zone trembled at high frequencies, radiating energy that shook the ground above.
If the Cascadia fault were to generate a quake similar to the one in , then officials might want to prepare for high-energy shaking in some areas near the fault. Predators such as grey wolves tend to roam greater distances than their prey, according to a broad study of terrestrial mammals. Which land animal has the longest migration?
Baby tiger sharks eat songbirds like sparrows, doves, study finds
Biologists have long suspected that caribou journey the farthest on their annual round trip, but hard evidence was lacking. They found that caribou Rangifer tarandus do indeed migrate the farthest between their summer and winter ranges, with some herds covering more than 1, kilometres in a round trip. But the prize for most kilometres covered in a year went to another mammal: the grey wolf Canis lupus. The absolute champion was a male from Mongolia that covered a jaw-dropping 7, km in a single year.
In general, predators covered more ground than their prey.
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Sadly, human manipulation of landscapes has broken or truncated many ancient migrations. The researchers call for the conservation of these epic animal journeys, as well as the species that undertake them. A night of inadequate sleep can trigger not only an overwhelming urge to nap, but also a rise in anxiety. In fact, when sleep-deprived, half of the study participants reported anxiety levels typically seen in people with clinical anxiety disorders. And online surveys completed by a larger number of volunteers showed that ordinary fluctuations in nightly sleep quality predict next-day anxiety levels.
The team also imaged the brains of the sleep-lab participants as they watched video clips designed to conjure up negative emotions. People who watched these videos after sleep deprivation showed less activity in the prefrontal cortex PFC , an area involved in emotional control, than they did when they were well-rested. Those with the greatest drops in PFC activity reported the largest spikes in anxiety after an all-nighter.
Like teenage boys, tiger sharks gobble up virtually everything in sight. Further inspection revealed that the plumes belonged to a Brown Thrasher, a slender songbird that frequents gardens and thickets in the eastern United States.
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Intrigued, Drymon checked the scientific literature for clues. But no one knew whether bite-sized morsels like warblers, wrens, and sparrows were a regular part of the tiger shark diet, or whether they were anomalies like the horse head and the chicken coop. Drymon has been looking into the matter ever since—and appears to have solved the mystery in part.
Roughly two billion birds cross the Gulf of Mexico each spring, and even more likely fly back over it in the fall. Some are inevitably blown into the sea by storms, or crash onto the waves while facing headwinds, fog, or disorienting lights from oil and gas platforms. Drymon, who hopes to one day witness this phenomenon in action, suspects that tiger sharks prey on passerines in the same spectacular fashion they devour albatross fledglings in the Hawaiian islands: They lift their upper jaw out of the water and drag the bird down in one swift move, he says.
Interestingly, no other shark species seems to be taking advantage of this easy, migratory food source; as far as we know, only tiger sharks have developed a taste for marine and terrestrial birds, Drymon says. He does his research off the coast of Alabama and Mississippi, using a mile-long line with baited hooks to haul in large fishy predators. He and his team then wrestle each catch onto the boat—no easy task, considering tiger sharks grow up to 15 feet long and are quick to bite—and pump its stomach with a basic, clear tube. In most cases, the animal is released unharmed.
Natural Sciences. American researchers proposed that the birds were migrating, became exhausted and fell into the sea before reaching land—due to inclement weather. But they did not explain why migrating birds are falling from the sky and into the sea immediately after starting their journey—a trek for which they usually prepare carefully, accumulating ample fat reserves, strategically timed.
Leave it to Prof. Yosef observed that in the Negev European bee-eaters, Merops apiaster, migrate through the Eilat bottleneck every spring and autumn.