Science-- there's something for everyone

Friday, August 31, 2012

Do infants have a fear of heights?

You may be familiar with experiments that show that infants will not willingly crawl over cliffs. If they get to a drop-off edge, they usually will not proceed any further. This has been interpreted to mean that babies have a natural fear of heights. According to Kari Kretch and Karen Adolph of New York University, this is the wrong interpretation. Instead, infants simply become more adept at gauging their physical limits.

Many of the earlier avoidance studies have involved watching whether babies will crawl across a virtual cliff, generally a sheet of glass or plexiglass. You can see an example of such an experiment below:

The obvious drawback is that the drop-off is only virtual. Babies learn very quickly that they won’t actually fall if they move onto the glass. This makes it difficult to score their innate tendencies. To avoid this problem, infants were placed near actual slopes and drop-offs, with spotters available to catch them before they fell. The researchers compared novice and experienced crawlers with novice and experienced walkers.

The biggest predictor of whether an infant would attempt to cross a drop-off was how long he’d been using that mode of travel (what the authors refer to as ‘posture-specific locomotor experience’). Babies with less than forty days of experience with either crawling or walking would move over the edge. After having successfully crawled or walked for ninety days, they rarely needed to be caught at the cliff’s edge. In other words, infants who had learned to avoid cliff edges while crawling had to relearn to avoid them once they started walking. They neither gain nor retain a fear of heights.

As the authors state:
Crawling experience taught infants to perceive affordances for crawling, and walking experience taught infants to perceive affordances for walking.

Thursday, August 30, 2012

To attract native birds, plant native vegetation

I like this story for two reasons. First, it goes against my pre-conceived ideas and I always love that. And second, it gives practical suggestions for what people can do to make their yards friendly to birds. Susannah Lerman of the University of Massachusetts and her colleagues have found that wild birds can forage more successfully in yards with native plant life.

Why did this surprise me? The yards in question were in Phoenix, Arizona. That means that the researchers compared xeric (desert-like) gardens with mesic (moist, grassy) gardens. Although it seems obvious that birds would prefer native plants, I still thought birds would find more food in a lusher landscape. Not so.

Twenty homeowners volunteered their yards for science. The yards were divided evenly between mesic and xeric gardens. Two seed trays containing an exact number of seeds mixed with sand were placed in each yard. Thus, any bird feeding at a tray would have to spend some time sifting through the sand to pick out the seeds. At some point, each bird will decide that it’s no longer worth the energy or risk of predation to keep poring through the seed tray. The more food that’s available in the vicinity of the seed tray, the sooner birds will abandon it and forage elsewhere.

Birds stuck with the seed trays for much longer in mesic than in xeric yards. That is, the birds were less able to find the food they needed in the lusher yards than in the desert yards. The grass may be greener on the other side of the fence, but that’s no enticement to native birds.

Photo of a xeric, or desert, yard in Phoenix.
Photo of a non-native grass lawn in Phoenix with a house, garage and cars in the background.

Top: A xeric, or desert, yard in Phoenix: This yard with native vegetation is a mini-refuge for birds.
Bottom: A mesic yard in Phoenix, with its non-native grass lawn, is less attractive to native birds.
Credit: Susannah Lerman.

These data suggest that any homeowner who wishes to attract birds to his yard consider landscaping it with native plants. Since this also means that the owner will use less water and chemicals to maintain that yard, it’s a win-win for everyone.

Wednesday, August 29, 2012

Just for fun: Rolling in the Higgs

Tim Blais is the theoretical physicist and musician who created A Capella Science. You know that augurs good things. Here’s his first offering: Rolling in the Higgs (Adele Parody).

For those who wish to follow along, here are the lyrics:

There's a collider under Geneva
Reaching new energies that we've never achieved before
Finally we can see with this machine
A brand new data peak at 125 GeV
See how gluons and vector bosons fuse
Muons and gamma rays emerge from something new
There's a collider under Geneva
Making one particle that we've never seen before

The complex scalar
Elusive boson
Escaped detection by the LEP and Tevatron
The complex scalar
What is its purpose?
It's got me thinking

We could have had a model (Particle breakthrough, at the LHC)
Without a scalar field (5-sigma result, could it be the Higgs)
But symmetry requires no mass (Particle breakthrough, at the LHC)
So we break it, with the Higgs (5-sigma result, could it be the Higgs)

Baby I have a theory to be told
The standard model used to discover our quantum world
SU(3), U(1), SU(2)'s our gauge
Make a transform and the equations shouldn't change

The particles then must all be massless
Cause mass terms vary under gauge transformation
The one solution is spontaneous
Symmetry breaking

Roll your vacuum to minimum potential
Break your SU(2) down to massless modes
Into mass terms of gauge bosons they go
Fermions sink in like skiers into snow

Lyrics and arrangement by Tim Blais and A Capella Science
Original music by Adele.

Tuesday, August 28, 2012

Don’t sacrifice sleep to study

Here’s a little something for everyone going back to school in the fall. For optimal academic performance, is it better to sleep or to study? According to Cari Gillen-O’Neel, Virginia W. Huynh and Andrew J. Fuligni of the University of California, Los Angeles, if you have to choose between studying and getting a good night’s sleep, get some shuteye.

For their study, Gillen-O’Neel and her colleagues recruited 9th grade students from three Los Angeles schools.  For two weeks, daily reports were collected on study time, sleep time and academic functioning. The fortnight of data collection was repeated for the same kids in subsequent grades. Students who returned all fourteen reports received $30. If the reports were all filled in correctly, they also got a couple of movie passes. This resulted in an over 96% compliance rate.

Each day, the kids recorded exactly how much time they’d spent studying and how much sleep they’d gotten the previous night. The students also indicated how they’d done in school. Had they understood any new material that was presented? Had they done well on tests or quizzes?

So, what were the results? Deviating from the average study duration (which was just over an hour/night regardless of grade level) did not affect the next day’s academic performance for 9th graders. On the other hand, increased study time actually had a negative effect for older kids. Tenth through twelfth graders did progressively worse in school the more hours they studied. This rather counterintuitive result may be explained by the fact that study time and sleep time were inversely correlated. That is, the more time spent studying, the less time spent sleeping.

Understand that this does not mean that kids who don’t study do as well as kids who do. It just means that for kids who usually study, taking a night off didn’t affect their grades, whereas skipping sleep to cram in more study time did have an adverse effect. By all means, students who want to do well in school should spend time studying. They just shouldn’t sacrifice sleep to do so.

It actually does benefit students to study more as long as they don’t take the extra time away from sleep. The authors suggest that students develop a uniform and consistent study schedule so that long nights aren’t required, and that they take any needed extra study time away from socializing rather than from sleeping. I’m sure this advice will go over well with high school students, a demographic well known for not procrastinating and being willing to give up time with friends.

Monday, August 27, 2012

Good news for astronauts’ bones

Bone loss is a huge problem for people working in zero or very low gravity. The more time a person spends in such an environment, the worse the problem can get. Scientists have tried to mitigate this loss by adding exercise equipment to space stations, but it hasn’t been particularly successful. In 2008, the Advanced Resistive Exercise Device (ARED) was added to the International Space Station (ISS). Scott Smith from NASA and his colleagues were interested in whether this new device, in conjunction with controlled nutrition, could decrease or eliminate bone loss in astronauts.

Japan Aerospace Exploration Agency (JAXA) astronaut Koichi Wakata, Expedition 19/20 flight engineer, exercises using the advanced Resistive Exercise Device (aRED) in the Unity node of the International Space Station.
Credit: NASA.

Thirteen astronauts who spent between 48 and 215 days aboard the ISS between 2006 and 2009 were the subjects of the experiments. They were each given specific exercise protocols to follow and asked to record what they ate. At various times before, during and after their missions, they were subjected to bone density and blood tests.

The ARED has distinct advantages over previous space exercise machines in that it allows for more consistent load-bearing and a wider range of movements. But would that make enough of a difference? Well, the results are in: astronauts using the ARED can avoid bone loss, as long as they also consume enough calories and get enough vitamin D.

This news is especially encouraging for anyone who dreams of participating in a mission to MARS. Astronauts on the ISS may be able to return to Earth if their health becomes compromised, but MARS explorers will have no such option.

Commander Scott Kelly demonstrates the ARED below:

Saturday, August 25, 2012

The super brains of SuperAgers

Okay, this title is a bit misleading. The brains in question are fairly normal for people in their fifties. The only thing super about them is that they happen to reside in the heads of people who are over 80. Emily Rogalski and her colleagues from Northwestern University studied what gives this subset of people such a cognitive edge as they age.

Twelve people dubbed ‘SuperAgers’ were identified as people who, although in their eighties, performed on episodic memory tests like people in their fifties. People who really were in their fifties and sixties served as middle-aged controls. None of the subjects in the study had any evidence of neurologic or psychiatric disease.

Not only did the SuperAgers perform as well or better than middle-aged controls on recall tests, but they also lacked the cortical thinning evident in their age-mates. In fact, one area of the brain (the left anterior cingulate) was actually thicker in eighty-year-old SuperAgers than in middle-aged people. This is contrary to the expectation that our brains atrophy as we age. For a select few, gray matter loss is not a compulsory part of aging.

What makes a SuperAger? Unfortunately, we don’t know. These lucky individuals may have been born with thicker cortexes to begin with, or something in their genetics or environment may have shielded them from cortical loss. The twelve SuperAgers in the study did not report any particular cognitive gifts earlier in life. They’ve always had average memories and intelligence. They just didn’t lose those abilities in their so-called declining years.

Friday, August 24, 2012

Introducing the cave robber spider

Meet Trogloraptor (‘cave robber’) marchingtoni (named for cave biologist Neil Marchinton), a spider so unusual that it founded not only a new genus, but also a new spider family. Needless to say, the discovery of a new family of North American spider is not an every day occurrence, and cause for celebration for the three arachnologists from the California Academy of Sciences who identified it.

If you’ve done any time exploring caves in Oregon or California, you may have already met T. marchingtoni. The creature is about four inches across at maximum spread and likes to hang from cave ceilings. Oh, and did I mention the claws? The authors speculate that they may be used as part of a novel and undoubtedly ruthless hunting technique.

Credit: Griswold CE, Audisio T, Ledford JM.

If you’re interested, you can read a detailed description of the spiders from chelicera to spinneret in the ZooKeys paper. And in case you’re wondering what it takes to find reclusive cave-dwelling spiders, here’s a picture of the three authors in their work clothes.


Left to right: Joel Ledford, Charles Griswold and Tracy Audisio.
Credit: Griswold CE, Audisio T, Ledford JM.

Thursday, August 23, 2012

School lunches not so bad

School lunch programs have been criticized for providing too few fruits and vegetables and too much sugar and fat. But is this criticism fair? While school lunch programs could undoubtedly be better, you may be surprised to hear that they are a vast improvement over most sack lunches. So says a new analysis led by Craig Johnston of the Baylor College of Medicine.

The National School Lunch Program (NSLP) provides free lunches to qualifying school children (more affluent children can buy the same meals). The NSLP has specific guidelines and policies to which it must adhere. These policies are based on Dietary Guidelines for Americans and include limits on total calories as well as on specific foods such as sugar-sweetened drinks or salty snacks. Needless to say, any similar limits on lunches prepared at home are strictly voluntary.

Second-graders from seven elementary schools in southeast Texas participated in the study. Roughly one quarter of the students belonged to each of the following demographics: white, black, Asian and Hispanic. About a third of the kids qualified for free or reduced price lunches. On three random days, trained observers recorded everything the kids had for lunch.

Across the board, lunches obtained from the school were more nutritious than lunches prepared at home. The school lunches were far more likely to include fruits and vegetables and less likely to include sugary or fatty snacks. When questioned, parents commonly stated that they provided foods they knew their kids would actually eat, rather than items that would most likely be discarded.

This brings us to the biggest caveat of the study. Researchers were only noting what foods the kids received, not what they actually ate. However, there is still reason to think the study is valid. For one thing, the school lunches were not prepackaged in any way and kids were free to choose what to put on their trays. Most children will at least taste something they willingly select. For another, although kids might not eat the vegetable they put on their tray, they definitely won’t drink the sugary beverage that isn’t even an option. By providing healthy options, you can almost guarantee that children will get some nutrition out of their meals.

Fruits, vegetables and salads provided by NSLP to Washington-Lee High School in Arlington, Virginia on 10/19/2011. 
USDA photo by Bob Nichols.

Wednesday, August 22, 2012

Just for fun: Wildlife overpasses

In an effort to provide animals with more useable habitat despite an increasingly subdivided world, some developers have built wildlife overpasses. These are bridges that connect natural areas on opposite sides of a road. In theory, and in practice, animals can cross the bridge to gain access to territories on the other side of the road. The World Geography has collected some of the most beautiful of these bridges.

Here's my favorite, an ecoduct on the A1 Highway in the Veluwe region of the Netherlands, photographed by Siebe Swart.

However, I'm also partial to this attempt to safely move red crabs across Christmas Island during their annual migration to the sea.

Tuesday, August 21, 2012

Do AIDS patients benefit from going to specialized pharmacies?

Nowadays, HIV patients can expect to live reasonably long lives. However, to do so, they must vigilantly take all their medication. Unfortunately, only a third of patients take at least 90% of their drugs as prescribed and on time. Doctors wondered whether sending their patients to specialized HIV pharmacies would increase compliance with drug protocols. The short answer is ‘maybe’.

HIV-specialized pharmacies employ pharmacists specifically trained in the care and treatment of AIDS patients. The training of these professionals includes the cultural impacts of living with HIV, as well as ways to educate AIDS patients and encourage compliance. In addition, these pharmacies are stocked with HIV/AIDS medications at all times.

The researchers compared the ‘proportion of days covered’ (PDC) of patients using HIV-specialized pharmacies to that of patients using ordinary pharmacies. The PDC is simply the number of days/month a patient could be taking his full drug regimen, based on refill data. For example, if a drug is to be taken twice daily but the patient only refills a 60 pill bottle every other month, his PDC for that drug is 50%. The measure is a bit more complicated because the patients in the study were each taking at least three different medications, but you get the idea. Patients were also ranked for persistence, that is, for continuing with their drug protocols.

The roughly 7000 patients using HIV-specialized pharmacies had slightly higher PDCs than a similar group of people using traditional pharmacies. In addition, patient persistence was greater among specialized pharmacy users. This certainly seems like a win for HIV-specialized pharmacies, doesn’t it?

Just a couple of problems with this study. First, the data was collected from a single pharmacy chain. This means that some patients might have received low marks for PDC or persistence when they were actually filling their prescriptions at other pharmacies. Second, patients who had been told to discontinue a medication also received a low PDC rating when they failed to refill that prescription. It’s impossible to say how much these two factors affected the overall results.

Finally, four of the six authors on the paper work for Walgreens, including lead author Patricia Murphy (the other two researchers are from the University of California, San Francisco). Not surprisingly, the single pharmacy chain used in the study was Walgreens and Walgreens also funded the study. Perhaps this wasn’t a source of conflict, but it may have been.

I would have liked to see data on whether HIV/AIDS patients felt more comfortable using a pharmacy they knew specialized in HIV treatment. I also wonder how non-AIDS sufferers feel about using a pharmacy that specializes in HIV treatment. As it is, there may be a slight benefit to the AIDS community of establishing specialized pharmacies, but it probably isn’t dramatic.

Monday, August 20, 2012

The mystery of Neanderthals’ large right arms solved

Researchers from the Universities of Cambridge, Oxford and Pennsylvania State have answered an anthropological puzzle. Why are the right arms of Neanderthals so much more muscular than their left arms? They obviously used their right arms more heavily than their lefts, but for what tasks? Two leading contenders include thrusting spears and scraping hides.

To compare these two activities, thirteen right-handed able-bodied men were set some spearing and scraping tasks. Pieces of carpet stood in for game animals. The volunteers thrust mock spears into scraps of carpet and scraped fibers from other carpet fragments, all while hooked up to electrodes that measured muscle usage.

Spear thrusting seems like an obvious choose for asymmetrical arm use. Unfortunately for this popular hypothesis, the researchers found that this activity makes greater use of the non-dominant (generally left) arm. So, scratch that off the list. In contrast, some of the motions involved in scraping a hide did significantly favor the right arm.

This actually makes sense if you consider that for every successful spear thrust there follows many hours of hide scraping. Thus, it’s not surprising that hide preparation makes a much greater impact on Neanderthals’ anatomy.

PZ Myers of Pharyngula has an alternate explanation.

Sunday, August 19, 2012

A new treatment for the flu

Sam Sanderson from the University of Nebraska and his colleagues from various San Diego institutions may have found a new weapon in the war against the flu. To explain, let's take a look at our immune system.

Perhaps the most well known component of our immune system involves the ‘acquired immune response’ in which each tiny invader is attacked by specific antibodies. However, there is also an ‘innate immune system’. Briefly, upon encountering pathogens, the body quickly releases protein cues that encourage immune cells to flock to the area and contain the infection until more troops can be summoned to dispose of the bugs. Unlike the acquired immune response, the innate system is nonspecific. As such, it can be initiated much more quickly. Where it may take a few days for antibody assembly to go into full production, the innate response takes only hours.

One of the components of innate response is the glycoprotein C5a. The binding of C5a to its receptor is a key occurrence in the cascade of events that results in the innate response. Blocking this receptor has a deleterious effect on mice suffering from influenza.

There is a synthetic version of human C5a called EP67. Sanderson  and his colleagues found that chemicals involved in the innate immune system were released within two hours of administering EP67 to mice. More importantly, 100% of mice given EP67 within a day of infection with a lethal dose of influenza survived that infection.

This is particularly significant because influenza is a tricky little bugger. The virus can actually suppress the immune system for up to 48 hours, meaning that most hosts will suffer from the full-blown and highly shareable symptoms we associate with having the flu. EP67 seems able to circumvent this delaying tactic.

Interestingly, EP67 has already been used as a vaccine adjuvant. This is a nonspecific chemical that boosts the effectiveness of the vaccine. Now, it seems that EP67 could function on its own as an emergency treatment against a whole host of infections, many of which may have no vaccines.

Saturday, August 18, 2012

Rate movies for smoking

James Sargent and Susanne Tanski from Dartmouth and Mike Stoolmiller from the University of Oregon have thought of a way to decrease adolescent smoking rates. They suggest that film raters treat smoking like extreme violence and give movies that show smoking an ‘R’ rating. Currently, smoking is not considered a determining factor by the Motion Picture Association of America ratings system.

To test the relationship between movie ratings and smoking, about 6500 kids ages 10 to 14 were randomly recruited by telephone. Over the next two years, the youngsters were surveyed every eight months for tobacco and alcohol use. At each interview, the kids were given a list of 50 current and recent movie titles (out of a pool of over 500 films) and asked to list the ones they’d seen. All the movies had been screened by people carefully counting every incidence of onscreen smoking, no matter how trivial to the plot.

The probability of a kid commencing to smoke was highly correlated with his having seen more incidents of smoking on film. This isn’t surprising, considering that this year, the Surgeon General issued a report stating:
The evidence is sufficient to conclude that there is a causal relationship between depictions of smoking in movies and the initiation of smoking among young people.
Interestingly, most of the onscreen smoking was seen during PG-13 movies, mainly because that was the most common rating for movies watched by kids in the study age group. Therefore, the authors conclude that if the depiction of smoking earned a film an automatic R rating, children in the vulnerable 10-14 year age range would see far less smoking and fewer of them would begin smoking themselves. In fact, they predict a reduction in overall smoking onset of 18% by making this simple change.

Well, I say simple, though I’m sure that filmmakers and theaters alike would balk at such a change. Moviegoers might also object if the new rating made it more difficult for them to see their favorite films. On the plus side, if smoking were enough to earn a film an R rating, perhaps most directors would choose to simply eliminate this usually non-essential plot point from their films. That would be a win for everyone involved.

By the way, I hope I haven’t beguiled anyone into starting to smoke by including the enticing graphic above.

Friday, August 17, 2012

To improve dieting success, cut your food up

Here’s a simple trick to make yourself believe that you’re ingesting more calories than you actually are: cut your food into small pieces. Apparently, this works on both humans and rats.

Devina Wadhera of Arizona State University presented her findings last month at the annual meeting of the Society for the Study of Ingestive Behavior in Zurich, Switzerland. She gave rats a choice of either one big chunk of food, or four smaller chunks that added up to the same weight as the big piece. The rats preferred the four smaller pieces. This was also true when the choice was between one piece of food and ten smaller pieces. Rats not only chose the maze pathways that led to the smaller pieces, but rushed there more quickly.

How about people? Wadhera gave 300 college students either a whole bagel with cream cheese, or a similar bagel with the same amount of cream cheese cut into quarters. The students ate more of the whole bagel than the cut up bagel. Twenty minutes after the students had eaten their bagels, they were offered a free (and unbeknownst to them, carefully measured) meal and told to eat as much as they liked. Uneaten portions of both bagel and meal were then weighed. Students who had gotten the quartered bagel ate less of the subsequent meal, even if they’d also already eaten less of the bagel.

So, rats enjoy small portions more, and humans eat less when presented with smaller portions. If the college students had been required to race to either the cut up bagel or the whole bagel, it might have been a resounding victory for cutting up food. As it is, this may be an easy way to make a diet seem less restrictive.

Thursday, August 16, 2012

You can’t spot a liar

Think you can tell whether a person is lying by watching his eyes? You’re probably deceiving yourself. Richard Wiseman, a psychologist from the University of Hertfordshire with a love of the weird and quirky (see my ‘Just for fun’ post about him), and his colleagues from the Universities of Edinburgh and British Columbia have tested the notion that you can detect lies by watching eye movements. They found that you could not.

The belief in a connection between eye-movement and veracity is widespread. This view holds that a right-handed person will look up and to the left when drawing a thought out of his memory, but up and to the right when fabricating a thought. Thus, if a person glances up to the right as they answer a question, he’s probably lying. Except that’s not what Wise and his colleagues found.

The researchers conducted a number of experiments in which right-handed participants were filmed either lying or telling the truth. Independent observers watched the films with the sound off and counted how often each participant had looked up to the left or right. There was no connection between direction of gaze and truth-telling. In addition, people who had been primed to expect liars to look up and right were no better at detecting liars than those who had received no such instruction. Taken together, these data strongly suggest that the idea that you can tell if a person is lying by watching for eye movements is rubbish.

To be fair, the liars in this study were given a few minutes to compose their stories ahead of time. That is, they were not improvising lies on the spot and this foreknowledge may have affected their eye movements. However, Caroline Watt of the University of Edinburgh says that the experiments mirror real life, in which people also often have a moment or two to prepare a lie.

Wednesday, August 15, 2012

Just for fun: Curiosity rover's 360 perspective

The Mars rover Curiosity successfully landed a few days ago and is already hard at work transmitting images. Here's a panoramic sample assembled by Andrew Bodrov

Curiosity rover: Martian solar day 2 in New Mexico

If it won't play on your browser, try this instead.

Tuesday, August 14, 2012

The nocebo

You’re familiar with the placebo effect, but have you ever heard of the ‘nocebo’ effect? Just as the illusion of treatment can make people feel better, the suggestion of negative effects can make people feel worse. For example, reading about the possible side effects of a treatment can make people believe they suffer from those ailments. Remember, as with the placebo, the negative effects are not caused by any real treatment. In fact, patients receiving placebos in clinical trials will have negative nocebo effects if the tested medicine is perceived to have those effects.

This means that participants will sometimes drop out of clinical trials due to adverse reactions, even when they were actually in the placebo branch of that study. People also report less satisfaction with pharmacologically identical generic drugs than with name brand preparations.

This puts doctors in a precarious position. Ethically, they are required to make sure their patients are informed about the possible risks and side effects of treatments. However, just mentioning possible problems makes it more likely that their patients will suffer from them. Contrary to common assumption, forewarning a patient that a procedure will ‘sting’ or ‘burn’ often increases the perceived pain. Again, this is true even if the treatment was a sham and the patient never actually got the treatment.

Winfried Häuser of the Technische Universität München and his colleagues have a few suggestions for how doctors can navigate the treacherous waters between giving too little and too much information. Physicians can emphasize the rarity of side effects, or they can ask patients to willingly forego learning about unlikely and/or minor side effects. Personally, I think the latter choice would turn me into a hypochondriac on the spot. Of course, phrasing matters. What would you choose if your doctor asked you the following? 
A relatively small proportion of patients who take Drug X experience various side effects that they find bothersome but are not life threatening or severely impairing. Based on research, we know that patients who are told about these sorts of side effects are more likely to experience them than those who are not told. Do you want me to inform you about these side effects or not?

Monday, August 13, 2012

How many atoms does it take to cast a shadow?

According to new research led by David Kielpinski and Erik Streed of Griffith University, Brisbane, the answer is one. Granted, the researchers used ytterbium, a rather large atom with an atomic weight of 174. Still, this remarkable result has far-reaching implications for many fields, including biology.

More specifically, the scientists measured the absorption of photons by single ytterbium ions. They did this by first trapping the individual ions in a supercooled vacuum and then bombarding them with light of precisely 369.5 nm in wavelength. Beyond making a nice shadow, this allowed the physicists to calculate the maximum signal extraction per photon, a useful bit of information to say the least.

Because we are able to predict how dark a single atom should be, as in how much light it should absorb in forming a shadow, we can measure if the microscope is achieving the maximum contrast allowed by physics. This is important if you want to look at very small and fragile biological samples such as DNA strands where exposure to too much UV light or x-rays will harm the material. We can now predict how much light is needed to observe processes within cells, under optimum microscopy conditions, without crossing the threshold and destroying them.
No news yet on how many atoms it takes to make shadow puppets.

Sunday, August 12, 2012

Spray-on batteries

Conventional lithium-ion batteries are pretty useful, but they have their limitations. For one thing, because of the way their components are housed in metal canisters, they can only be manufactured as cylinders or rectangles. Pulickel Ajayan, Neelam Singh and their Rice University Colleagues have solved this problem by developing paintable batteries.

Paintable battery concept.

(a)Simplified view of a conventional Li-ion battery, a multilayer device assembled by tightly wound ‘jellyroll’ sandwich of anode-separator-cathode layers. 
(b) Direct fabrication of Li-ion battery on the surface of interest by sequentially spraying component paints stencil masks tailored to desired geometry and surface.

Each component is spray-painted onto a surface in layers, as shown above. The researchers were able to use this technique to apply batteries to a number of materials, including glass, stainless steel and flexible polymer sheets. They even fabricated a battery directly onto the curved surface of a ceramic mug.

Saturday, August 11, 2012

My 1000th post!

This is my 1000th blog post! I thought I'd celebrate by republishing my most popular post. In case you missed it:

Babies can quantify
First posted 12/22/2010. 

It has been known since 1992 that babies as young as five months can do simple arithmetic (1+1=2). However, it was not thought that young children could compare more fluid amounts of things, such as quantities of water or sand. Kristy VanMarie from the University of Missouri and Karen Wynn of Yale have found that babies as young as ten months old can tell a larger amount of cereal from a lesser amount.

The experiment was very simple. The researchers poured cereal into cups and let the babies choose which cup they preferred. Starting at about ten months, as long as one cup had at least three times as much as the other, the babies would consistently choose the larger amount. At around 14 months, the babies could even remember which cup held more when the amounts were poured into opaque cups.

As an aside, the arithmetic experiments (also run by Karen Wynn) relied on the babies’ attention spans, rather than on their ability to choose an object. As an example, the five-month old babies were shown one doll on a table. A screen was lowered in front of that doll. The babies then watched as an experimenter added one more doll behind the screen. When the curtain was raised, there were either one or two dolls there. If there was only one doll, the babies stared for a lot longer than if there were two dolls. In other words, the babies appeared to be nonchalant about the fact that 1+1=2 but surprised to find that 1+1=1. The same results were found with subtraction: babies stared longer when removing one doll from behind a screen did not appear to decrease the total number of dolls from 2 to 1.

It seems that every time an experiment is run on the cognitive ability of babies, they get smarter. We really are an amazing species.

Friday, August 10, 2012

Fifth Pluto moon discovered

A year ago, I wrote that Pluto had four moons.  Make that five. The cosmologists at the SETI (Search for Extraterrestrial Intelligence) Institute and NASA/ESA have found a fifth moon lurking in their Hubble images. They hadn’t even gotten around to naming the fourth moon yet, which is still designated ‘P4’. Consequently, the newest one is ‘P5’.

Hubble image of Pluto and its moons

This image, taken by NASA's Hubble Space Telescope, shows five moons orbiting the distant, icy dwarf planet Pluto. The green circle marks the newly discovered moon, designated P5, as photographed by Hubble's Wide Field Camera 3 on July 7.
Credit: NASA; ESA; M. Showalter, SETI Institute

The four newer moons (Hydra, Nix, P4 and P5) were all also discovered in images from the Hubble Space Telescope. Charon, discovered in 1978, is the only one of Pluto’s moons that a person couldn’t easily circumnavigate on foot (especially considering that you’d be all but weightless). P5 is estimated to have an irregular shape that ranges from about 10 to 20 kilometers in diameter.

Although it’s not clear why tiny Pluto has a cluster of miniature moons, the leading hypothesis is that the grouping is the result of a collision that occurred soon after the formation of the solar system. It’s certainly possible that even more moons will be discovered in the future.

Not bad for an object that’s not even a planet.

You can hear a discussion about P5 on The Skeptics' Guide To The Universe - Podcast 366, starting at 27:30.

Thursday, August 9, 2012

What should you do with unwanted pharmaceuticals?

Many of us have medicine cabinets full of unused over-the-counter or prescription medicines. Some of these products are past their expiration dates, others may no longer be wanted or necessary. What should be done with them in order to achieve the least environmental hazard?  This is not a trivial problem. About 90 million kilograms (200 million pounds) of pharmaceuticals are disposed of each year. Steven Skerlos and his colleagues from the University of Michigan compared three options for disposing of unused drugs: throwing them in the trash, flushing them down the toilet, and returning them to the pharmacy for incineration.

To be clear, these three choices are not as distinct as they first appear. Some materials from both regular trash pickup and sewage get sent to incinerators. Drugs collected as solids from sewer systems and the ash from incinerated drugs end up in landfills along with drugs tossed in the trash. In addition, the authors considered how the drugs are transported at each stage, via private vehicle, commercial truck, or sewage line. Thus, sorting out the effects of these various alternatives can be rather complicated.

Incinerating 100% of all drugs may eliminate the risk of drug residues leaching into our soil, but the transportation from the home to the pharmacy to the incinerator to the landfill greatly increases gas emissions. On the other hand, flushing drugs all but eliminates transportation costs, but greatly increases environmental contamination with pharmaceuticals.

The ideal solution would be to have a sewage system that could thoroughly neutralize all pharmaceuticals.  Barring that, the next best option seems to be to throw drugs in the trash. That makes me feel good, since that’s what I’ve been doing anyway.  Of course, I haven’t been opening my bottles and mixing the contents with other trash within low-density polyethylene bags, as recommended by the White House Office of National Drug Control Policy.  Oops. 

Wednesday, August 8, 2012

Just for fun: Surgical tools

Norm Barker of Johns Hopkins specializes in photo-microscopy.  His work appears in books and museums.  For some reason, I find this photograph of miniature surgical tools fascinating and beautiful.


These surgical micro-burrs are used in everything from dentistry to neurosurgery. Each tip is highly specialized, made of high-quality stainless steel or titanium, and many of them have a diamond crust. Using these tools, surgeons can cut, clean, shape, smooth and carve even the hardest human bones. 

Norm Barker

You can see a few other examples of his work on this Scientific American slide show.

Tuesday, August 7, 2012

A robot that walks like a human

If I were working on a robot with a human gait, it would be in the hopes of one day creating R. Daneel Olivaw. Theresa Klein and Anthony Lewis of the University of Arizona have more pedestrian goals (pun intended). They hope to understand the mechanics of human locomotion.

Humans have a ‘central pattern generator’ (CPG) in the lumbar region of our spines. This neural network receives signals about terrain and environment, and produces the rhythmic signals required for walking. It’s thanks to the CPG that we don’t need to expend any conscious thought to the process of walking, even over uneven surfaces. The most simplistic CPG, a half-center oscillator (HCO), consists of only two neurons that together create a stable rhythm. It’s thought that infants have an HCO that induces them to make stepping motions long before they can actually walk.

In order to model human-style walking, Klein and Lewis gave a pair of humanoid robotic legs an HCO of their own. You can see the results below:

By disconnecting various sensors or by adding weights, they were able to alter the walking gait or give the legs a limp. They even found a configuration in which one lag dragged while the other stepped normally. Aside from the amusement this undoubtedly caused, these experiments also provided valuable information on how humans actually walk. In particular, the researchers showed that some of the rhythm and stabilization comes from the legs themselves, rather than from a central control. That is, feedback from the leg muscles (which bear different amounts of weight during different phases of the walking gait) can induce the legs to move reflexively without waiting for a command from the spinal chord.