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What's painting dark streaks on Mars?
MICHAEL NICHOLS/NGS
IN BRIEF Does water streak the Martian dunes?
When the female of the species is leader of the pack THE glass ceiling that keeps high-flying women from many of the top jobs is no obstacle for elephants, reindeer and sheep. In herd mammals like these, it’s often the females that lead the pack. A new insight into the group dynamics of herding, and why particular individuals take the lead, hints at why this might be. Larissa Conradt of the University of Sussex in the UK and her colleagues used a computer model to simulate the behaviour of a group of animals in which there is conflict between individuals over the destinations they want to move towards. In the model, each individual
moved according to a simple set of rules: avoid collisions, try to stay with nearby group members, and try to get to your preferred destination. The team found that two kinds of individual were best able to move the herd towards where they wanted to go. The first includes those with the most to gain from reaching their goal, such as hungry animals desperate for food. The second group was made up of individuals with the least to lose if the herd split in two (The American Naturalist, DOI: 10.1086/596532). The latter effect may explain why females get to be the leader in many herd mammals, because if the group breaks up it is the males that stand to lose mating opportunities. In either case, the end result is that animals with the most at stake have the greatest say in the outcome.
Subliminal messaging ‘works’ IF YOU ever felt paranoid about subliminal messages, you might be right to worry. Images we see but don’t consciously register have been shown to inform people’s decision-making. Joel Voss of Northwestern University in Evanston, Illinois, and colleagues showed volunteers 12 kaleidoscope images for 2 seconds each while they also performed an unrelated number 16 | NewScientist | 14 February 2009
task to distract them from consciously committing the images to memory. A minute later, volunteers were asked to look at pairs of similarlooking images and choose the one they had seen before. They were also asked whether they were sure, had “a feeling” they were right, or were just guessing. Those who took a shot in the dark were as successful as the rest.
“They were 70 to 80 per cent accurate; it would be only 50 per cent if it was chance,” says Voss (Nature Neuroscience, DOI: 10.1038/nn.2260). During the memory task, the volunteers’ brain activity was monitored by electrical sensors attached to their heads. As the pattern of activity differed between “guessers” and the other groups, it suggests that we access unconscious and conscious visual memories differently, says Voss.
WHAT’S painting Mars? Every spring, dark streaks appear on its polar dunes, which may be caused by liquid water near the surface – a fillip for the hunt for life. The dark streaks of sand a few metres wide slide downslope at about a metre a day. “They show a branching pattern, so it seems like some liquid material is flowing,” says Akos Kereszturi at the Collegium Budapest in Hungary. Kereszturi reckons they occur when molecules in surface water ice are attracted to molecules in the minerals below. His team’s computer models suggest this melts an ultrathin layer, which lubricates grains within the dune so they flow downwards (Icarus, DOI: 10.1016/j.icarus.2009.01.014). “That liquid water could exist near Mars’s surface at this moment is really interesting,” says Matt Balme of the UK’s Open University in Milton Keynes, “especially for its impact on the search for life.”
Green tea blocks cancer drug TOUTED as a means of cancer prevention, green tea capsules may have the opposite effect on people taking certain anti-cancer drugs. A team led by Axel Schönthal of the University of Southern California in Los Angeles gave mice with human multiple myeloma tumours the drug bortezomib (Velcade) or ECGC, an antioxidant found in green tea, or both together (Blood, DOI: 10.1182/blood-2008-07-171389). While bortezomib alone shrank the tumours, the mixture did not. Test-tube studies showed that the drug was inactivated by ECGC levels similar to those in a person who regularly takes capsules of green tea extract. These are higher than levels in someone who drinks a moderate amount of green tea.
IN BRIEF Does water streak the Martian dunes?
When the female of the species is leader of the pack THE glass ceiling that keeps high-flying women from many of the top jobs is no obstacle for elephants, reindeer and sheep. In herd mammals like these, it’s often the females that lead the pack. A new insight into the group dynamics of herding, and why particular individuals take the lead, hints at why this might be. Larissa Conradt of the University of Sussex in the UK and her colleagues used a computer model to simulate the behaviour of a group of animals in which there is conflict between individuals over the destinations they want to move towards. In the model, each individual
moved according to a simple set of rules: avoid collisions, try to stay with nearby group members, and try to get to your preferred destination. The team found that two kinds of individual were best able to move the herd towards where they wanted to go. The first includes those with the most to gain from reaching their goal, such as hungry animals desperate for food. The second group was made up of individuals with the least to lose if the herd split in two (The American Naturalist, DOI: 10.1086/596532). The latter effect may explain why females get to be the leader in many herd mammals, because if the group breaks up it is the males that stand to lose mating opportunities. In either case, the end result is that animals with the most at stake have the greatest say in the outcome.
Subliminal messaging ‘works’ IF YOU ever felt paranoid about subliminal messages, you might be right to worry. Images we see but don’t consciously register have been shown to inform people’s decision-making. Joel Voss of Northwestern University in Evanston, Illinois, and colleagues showed volunteers 12 kaleidoscope images for 2 seconds each while they also performed an unrelated number 16 | NewScientist | 14 February 2009
task to distract them from consciously committing the images to memory. A minute later, volunteers were asked to look at pairs of similarlooking images and choose the one they had seen before. They were also asked whether they were sure, had “a feeling” they were right, or were just guessing. Those who took a shot in the dark were as successful as the rest.
“They were 70 to 80 per cent accurate; it would be only 50 per cent if it was chance,” says Voss (Nature Neuroscience, DOI: 10.1038/nn.2260). During the memory task, the volunteers’ brain activity was monitored by electrical sensors attached to their heads. As the pattern of activity differed between “guessers” and the other groups, it suggests that we access unconscious and conscious visual memories differently, says Voss.
WHAT’S painting Mars? Every spring, dark streaks appear on its polar dunes, which may be caused by liquid water near the surface – a fillip for the hunt for life. The dark streaks of sand a few metres wide slide downslope at about a metre a day. “They show a branching pattern, so it seems like some liquid material is flowing,” says Akos Kereszturi at the Collegium Budapest in Hungary. Kereszturi reckons they occur when molecules in surface water ice are attracted to molecules in the minerals below. His team’s computer models suggest this melts an ultrathin layer, which lubricates grains within the dune so they flow downwards (Icarus, DOI: 10.1016/j.icarus.2009.01.014). “That liquid water could exist near Mars’s surface at this moment is really interesting,” says Matt Balme of the UK’s Open University in Milton Keynes, “especially for its impact on the search for life.”
Green tea blocks cancer drug TOUTED as a means of cancer prevention, green tea capsules may have the opposite effect on people taking certain anti-cancer drugs. A team led by Axel Schönthal of the University of Southern California in Los Angeles gave mice with human multiple myeloma tumours the drug bortezomib (Velcade) or ECGC, an antioxidant found in green tea, or both together (Blood, DOI: 10.1182/blood-2008-07-171389). While bortezomib alone shrank the tumours, the mixture did not. Test-tube studies showed that the drug was inactivated by ECGC levels similar to those in a person who regularly takes capsules of green tea extract. These are higher than levels in someone who drinks a moderate amount of green tea.