Van der Waals helps geckoes scale walls
Face it, it would be totally cool if we could clamber up surfaces as easily as geckoes do. We could scale skyscrapers, never fear when climbing ladders, and could completely eliminate that tacky dramatic moment in movies where the hero dangles precariously over the street a hundred storeys below. Of course, their sweaty fingers would never slip if they had some kind of adhesion mechanism—they could just climb right back up.
So how do geckoes manage it?
Well, unlike humans, geckoes have millions of microscopic hairs on the bottom of their feet, called setae. The tips of each of these setae are split into 100-1000 spatulae, which are so small that they’re narrower than the wavelength of visible light—less than 300 nano metres.
Clearly, some kind of intermolecular force between the gecko’s feet and a surface is responsible for adhesion, but it wasn’t until research in 2002 that we fully understood what was going in—for a while, scientists were throwing around theories like suction and chemical bonding.
Turns out, geckoes take advantage of the Van der Waals force.
Named after a nineteenth century Dutch physicist, Van der Waals forces are weak electrodynamic forces that act over tiny distances, yet bond almost any material. They’re created by fluctuations in charge distributions between molecules.
These weak forces can be strengthened as more and more of one surface touches the other—like, say if you had billions of spatulae coating your feet. These tiny hairs increase surface density, so on contact with the wall the gecko experiences a strong adhesive force
Essentially, this force means we can improve adhesion simply by increasing surface density, like subdividing a surface into countless small protrusions. It means that geometry—not chemistry—is the driving mechanism. A single setae can lift an ant; a million could lift a 20 kg child; and if geckoes used every setae simultaneously, they could support 130 kg.
These forces open up to a lot of applications in adhesives. Engineers at Berkeley and Stanford have developed biologically inspired synthetic adhesives that adhere like gecko pads, which have even been used on robotic climbers.
The James Webb Space Telescope, NASA’s next flagship space observatory, has passed a major milestone on its road to its planned 2018 launch: the delivery of the last three mirrors that will make up its complicated infrared-seeking innards.
The mirror delivery for the $8.8 billion James Webb Space Telescope lays a critical brick in the road toward deploying the most powerful space telescope ever built. When complete, the telescope is expected to have seven times the light-collecting power of its predecessor, the Hubble Space Telescope, and should provide answers to questions about the early universe and the chances of life on other planets.
The telescope “is an absolutely impressive piece of engineering and includes technologies that make this spacecraft unlike any other we’ve ever developed before,” NASA Administrator Charles Bolden said in a news conference here Monday (Feb. 3), adding that the telescope is on track for launch in 2018.
YAAAASSSS!! Get your life JWST! :D
Lichen P. chlorophanum on S-MRS Mars-analog substrate. Image: German Aerospace Center’s Institute of Planetary Research
Humans cannot hope to survive life on Mars without plenty of protection from the surface radiation, freezing night temperatures and dust storms on the red planet. So they could be excused for marveling at humble Antarctic lichen that has shown itself capable of going beyond survival and adapting to life in simulated Martian conditions.
The mere feat of surviving temperatures as low as -51 degrees C and enduring a radiation bombardment during a 34-day experiment might seem like an accomplishment by itself. But the lichen, a symbiotic mass of fungi and algae, also proved it could adapt physiologically to living a normal life in such harsh Martian conditions—as long as the lichen lived under “protected” conditions shielded from much of the radiation within “micro-niches” such as cracks in the Martian soil or rocks.
"There were no studies on adaptation to Martian conditions before," said Jean-Pierre de Vera, a scientist at the German Aerospace Center’s Institute of Planetary Research in Berlin, Germany. "Adaptation is very important to be investigated, because it tells you more about the interactions of life in relation to its environment."
Previous Mars simulation experiments focused on simply measuring the survival of organisms at the end of a given time period. By contrast, de Vera and his group of German and U.S. colleagues measured the lichen’s activities throughout the experiment that was detailed in the Sept. issue of the journal Planetary and Space Science. They wanted to see whether the lichen had continued its normal activities rather than simply clinging to life in a dormant state.
Two groups of lichen samples were placed inside a Mars simulation chamber about the size of a big pressure cooker, which itself sat within a fridge about the size of an armoire. That allowed researchers to simulate almost everything about Martian conditions such as atmospheric chemistry, pressure, temperatures, humidity and solar radiation—the lone exceptions being Martian gravity and the added contribution of galactic radiation.
One of the lichen samples in the Mars chamber was exposed to the full brunt of radiation expected on the Martian surface, while the second set of samples received a radiation dose almost 24 times lower to simulate life in the “protected” condition. A third group of lichen samples sat outside the chamber as a control.
Both lichen sample groups survived their month-long period under Martian conditions. But the heavier dose of radiation from a Xenon lamp simulating the surface radiation conditions kept the unprotected sample group from doing much beyond clinging to survival.
Honey Bees Equipped with Sensor Backpacks
If you care about what you’re going to eat in the future, you’d better start caring about bees. Scientists have known for a while that the world’s honey bee population is declining and it’s a giant problem because they’re a vital part of the ecosystem—about one third of the food that goes into our mouths relies on the pollination process.
The decline is thought to be related to the Varroa destructor (a parasitic mite), which seems to be a contributor to a wider phenomenon called Colony Collapse Disorder, where bee colonies spiral into abrupt decline and simply disappear.
Interestingly, Australia is free from these threats so far, and researchers want to find out why. In Tasmania’s capital, Hobart, researchers from the CSIRO recently fitted tiny sensors to the backs of 5,000 wild bees to monitor the population. To do this, they refrigerated the bees to make them sleepy, shaved a little part of their back, and quickly glued down the sensors before releasing them back into the wild.
The sensors only weigh five milligrams so they don’t impede the bees at all. ‘The bee can carry a lot of weight in pollen, in nectar, so this is like someone carrying a small backpack,’ explains Dr de Souza, CSIRO scientist. The sensors will provide vital data to help researchers construct a three dimensional model of the bees’ behaviour. As de Souza notes, ‘Using this technology, we aim to understand the bee’s relationship with its environment,’ and thus understand how they work best and what might cause a population collapse.
In the near future, the CSIRO hopes to scale the sensors down to 1 mm, so they can tag smaller insects like mosquitoes and fruit flies to study their populations too.
Even Dung Beetles Stargaze
Last year, an Ig Nobel Prize was given to researchers who discovered that dung beetles use the Milky Way to navigate. The Ig Nobels famously honour achievements that first “make people laugh, and then make them think”, and this particular achievement was a triumph of both physics and biology.
The study found that dung beetles (Scarabaeus lamarcki) can only see the very brightest stars in the sky, so at night when the huge band of the Milky Way stretches overhead, they are able to see a long line of bright light and hence use it to help travel in a straight path. To test this, the researchers made special little hats for the beetles—one type made out of black cardboard, and the other type, a control group, made out of clear material. They simulated the Milky Way in a planetarium, and found that when the hats blocked the view of the sky, the dung beetles had trouble navigating, and so they must use it as an orientation cue.
“It’s quite impressive for an animal that size,” said Professor Warrant, one of the researchers, because previously we only thought humans, birds and seals used the stars for orientation.
Researchers are now trying to figure out how dung beetles use other cues to navigate—one recent study found that they may use the sun to steer their balls of dung, but it will also be interesting to figure out how important each of these different cues are to the beetles.
If you happen to spot a Nine Armed Sea Star under the sand, perhaps it’s kindest to not disturb it. But you know, since this one has already been disturbed, watch how it flips itself over from being on its back… and then proceeds to leave. (Wouldn’t you?)
The Last Launch of Space Shuttle Endeavour
Space Shuttle Endeavour has retired from service, and for the moment NASA is reliant on Russian rockets to keep the International Space Station stocked up and operating. NASA is developing a replacement for the Shuttle – the Orion CEV – but for the moment, lets take a look at the Shuttle and remember the many years of sterling service it has given us.
Image credit: Dan Winters
This Woman Took Your Picture… From Saturn
Planetary scientist Carolyn Porco on the Cassini spacecraft, the possibility of life on Saturn’s moons, and seeing Earth from distant space.
by Chris Mooney
On Valentine’s Day 1990, from more than four billion miles away, the Voyager 1 spacecraft snapped our photo. From that distance, there wasn’t much to see; the resulting shot simply showed several light beams with a tiny speck in one of them. Earth.
But that didn’t stop the late celebrity astronomer Carl Sagan from writing rapturously about the meaning of this image, which he famously dubbed the “Pale Blue Dot.” “To me,” Sagan wrote of the picture, “it underscores our responsibility to deal more kindly with one another and to preserve and cherish the pale blue dot, the only home we’ve ever known.”
Sagan infused the “Pale Blue Dot” with significance, but the truth is that, thanks in part to the difficulty of the shot, it was never a very good image. Enter planetary scientist Carolyn Porco, one of Sagan’s scientific disciples and head of imaging science for the Cassini spacecraft, which is currently in orbit around Saturn and sending us back stunning images on a regular basis. “From day one,” explains Porco on the latest installment of the Inquring Minds podcast (stream above), “I had it in my mind that I wanted to do that picture, only better. I wanted to make it beautiful.”
Last month—appropriately enough, at a celebration for Sagan, dedicating his papers to the Library of Congress—Porco unveiled a new Pale Blue Dot image. Aesthetically, it is everything the original was not…
(read more: Mother Jones)
Grandma’s Experiences Leave a Mark on Your Genes
Your ancestors’ lousy childhoods or excellent adventures might change your personality, bequeathing anxiety or resilience by altering the epigenetic expressions of genes in the brain.
Darwin and Freud walk into a bar. Two alcoholic mice — a mother and her son — sit on two bar stools, lapping gin from two thimbles.
The mother mouse looks up and says, “Hey, geniuses, tell me how my son got into this sorry state.”
“Bad inheritance,” says Darwin.
“Bad mothering,” says Freud.
For over a hundred years, those two views — nature or nurture, biology or psychology — offered opposing explanations for how behaviors develop and persist, not only within a single individual but across generations.
And then, in 1992, two young scientists following in Freud’s and Darwin’s footsteps actually did walk into a bar. And by the time they walked out, a few beers later, they had begun to forge a revolutionary new synthesis of how life experiences could directly affect your genes — and not only your own life experiences, but those of your mother’s, grandmother’s and beyond.
The bar was in Madrid, where the Cajal Institute, Spain’s oldest academic center for the study of neurobiology, was holding an international meeting. Moshe Szyf, a molecular biologist and geneticist at McGill University in Montreal, had never studied psychology or neurology, but he had been talked into attending by a colleague who thought his work might have some application. Likewise, Michael Meaney, a McGill neurobiologist, had been talked into attending by the same colleague, who thought Meaney’s research into animal models of maternal neglect might benefit from Szyf’s perspective.
I always think about this article and various groups of people of colour that are suffering because of mental illnesses, neglect and addictions. The current state of some punjabi youth who are addicted to hard drugs have had grandparents murdered in the 1984 sikh genocide. Or native indians that are now alcoholics have had family go through brutal residential schools. And the list goes on for many marginalized groups. So when the governments try to deem that those atrocities are in the past, they are forgetting that actual genetic implications that those events are having on the generation today.
Close-up of a cell infected with HIV
Electron micrograph of HIV particles (pink) budding from the membrane of a host cell. HIV (human immunodeficiency virus) attacks CD4+ T-lymphocytes (specialised white blood cells), which are crucial in the body’s immune system.
It enters the cell and makes many copies of itself, which then destroy the cell as they emerge through its membrane. This severely weakens the immune system, causing AIDS (acquired immunodeficiency syndrome).
There is still no cure for AIDS, recent hopeful tests of supposedly healed patients have turned into a bitter loss and a re-infection.
Image by Thomas Deerinck