Science-- there's something for everyone

Monday, April 30, 2012

Just when you thought it was safe to drink your own urine

Contrary to popular mythology, urine is not necessarily sterile. Because many of the bacterial species found in the human bladder cannot be grown in the lab, they’ve long gone unidentified. However, new sequencing techniques allow researchers to catalog bacteria without the necessity of first cultivating them. In this way, Linda Brubaker from Loyola University Chicago and her colleagues from that school, Indiana University and the University of North Texas have been able to find bacteria growing in the bladders of even asymptomatic women.

In the past, if you wanted to get a DNA sequence you’d need to get your hands on a large quantity of that DNA. If you were interested in a microbe, this meant growing a vial full of the little buggers. Nowadays, this is no longer necessary. Not only do tiny amounts of DNA suffice, but you don’t even need to separate out the DNA by species prior to sequencing. Thus, the researchers were able to throw all the DNA they collected into one bag and pull out any bacterial sequences that happened to be in there.

Women who were already scheduled for surgery were asked to give their urine for science. They provided a ‘clean-catch’ (the pee-in-a-cup method of urine collection) before surgery. While they were anesthetized, urine was also obtained both by catheter and by syringe directly out of the bladder.

Bacteria were found using all three urine collection methods, even in women with no symptoms of urinary tract infection. In only two out of twenty-three women did syringe aspiration of urine directly from the bladder not yield bacteria.

The numbers and types of bacteria did differ between the different collection methods, indicating that contamination is occurring during so called ‘clean-catch’. However, there are clearly bacteria residing in the bladders of most women. Whether those bacteria are long-time residents or occasional squatters has yet to be seen. One thing’s for sure though: urine is not as sterile as we thought it was.

Sunday, April 29, 2012

Honesty is the healthiest policy for LGB people

One of the least surprising studies about homosexuality has come out recently. Did you know that lesbian, gay or bisexual (LGB) people have less depression and drug use if they are able to disclose their sexual orientation to a supportive parent?

In general, LGB adults have poorer health outcomes. They experience more mental health and substance abuse problems than their straight counterparts. Emily Rothman of Boston University and her colleagues from Emory University and the University of Massachusetts wondered whether this could be a result of the stress of hiding their sexual orientation from their parents.

It’s important to note that not all disclosures are created equally. Coming out to a supportive parent is not the same as coming out to an unsupportive or abusive parent. Therefore, the researchers looked at four groups of adults: heterosexuals, LGB people who had not disclosed their sexual orientation, LGB people who had disclosed their sexual orientation to a parent who reacted positively, and LGB people who had disclosed their sexual orientation to a parent who was unsupportive. For each group, risk behaviors such as illicit drug use, binge drinking, smoking were assessed. In addition, each participant was asked to self rate his or her physical and mental health.

The researchers observed the following trends. The LGB population as a whole had a higher rate of risk behaviors and poor mental and physical health than heterosexuals. Interestingly, there was a dichotomy between men and women on how helpful it was to tell parents at all. Lesbian or bisexual girls fared better when they told parents their sexual orientation but non-disclosure did not affect health risks for gay or bisexual boys. However, both men and women who had come out to supportive parents had much better health outcomes than those whose parents had received the news poorly.

Although over 70% of LGB people said that they had eventually disclosed their sexual orientation to their parents, most of them were in their twenties when they did so. Only a third of the people who had come out to a parent had done so during their teens. Since disclosing sexual orientation to a supportive parent has definite health benefits, the authors suggest that parents be given guidelines on how best to support children, should they turn out to be LG or B.

Saturday, April 28, 2012

Better health through grooming

After individual ants are infected with a pathogen, the rest of their nest mates often become resistant to that pathogen.  How is this immunity aquired? Biologists from the Institute of Science and Technology, Austria, the Helmholtz Center and the University of Regensburg led by Sylvia Cremer and Matthias Konrad have found that healthy ants protect themselves from pathogens by grooming their sick compatriots.

The researchers exposed ants (Lasius neglectus) to the pathogen Metarhizium anisopliae, a fungus that produces tiny infectious spores called conidia. The infected insects were then allowed contact with their healthy nest matesEven when the pathogens were delivered at a dosage that should have killed half of exposed ants, only 2% of the nest mates died. 

The researchers found that direct contact was required to pass on this immunity. The nest mates picked up spores by licking the infected ants clean.  In so doing, the groomers managed to acquire a nonlethal infection. They were then able to fight off future attacks by the same pathogens.

Healthy workers of the invasive garden ant (Lasius neglectus) remove an infectious fungal pathogen (Metarhizium anisopliae) from an exposed nestmate by allogrooming. The pathogen-exposed individual was color-marked in order to distinguish it from the healthy ants.
Credit: Image courtesy of Institute of Science and Technlogy Austria.

Friday, April 27, 2012

Mobile stroke unit to the rescue

German researchers tested whether using specialized stroke ambulances called 'mobile stroke units' (MSU) could improve the outcomes of stroke victims. Patients who got an MSU received stroke treatment about 40 minutes earlier than their counterparts who were treated the conventional way. In case you're wondering, forty minutes can make a big difference during a stroke.

The most common treatment for stroke is thrombolysis, which dissolves the blood clots. However, this procedure must be started within a narrow window of time. More than half of stroke victims do not reach the hospital in time for the treatment to be effective. Thus, there’s a need to find a quicker way to treat patients.

Each MSU included a paramedic, stroke physician and neuroradiologist. Their specialized ambulance contained a CT scanner so that they were equipped to start thrombolytic treatment right at the emergency site or in the ambulance.

Patients who called in with the symptoms of a stroke that had occurred within the past two and a half hours were randomly assigned to get a visit from an MSU or from a regular ambulance.  People who received the MSU began stroke treatment immediately, an average of forty minutes earlier than the conventionally treated patients who got a regular ambulance.

A couple of points about this study. First, the study did not discuss the outcomes of non-stroke patients who were treated by the MSU. Presumably some fraction of the time the unit would respond to someone who hadn't actually had a stroke. Would those people have been better off with a conventional ambulance? And second, the study was not blinded.  That is, the patients and the medical teams knew very well whether or not an MSU was involved.

If having specialized stroke responders turns out to be impractical, perhaps regular emergency care providers could be provided with more training and equipment to deal with strokes. A few minutes can make a big difference in stroke recovery.

Thursday, April 26, 2012

Origin of bipedalism

Humans walk on two legs but our nearest cousins, chimpanzees and bonobos, don’t.  Therefore, sometime in our distant past, our ancestors must have transitioned from walking on four limbs to walking on two.  But why?  There are a few theories such as that having our hands free allowed us to carry objects and use tools, and that walking upright gave us a higher vantage point from which to survey our surroundings.

To investigate the carrying hypothesis, Susana Carvalho of the University of Cambridge, Dora Biro from the University of Oxford and an international team of anthropologists studied a group of wild chimpanzees.  Chimps can choose to walk on two legs for short distances if they wish.  The researches wondered if the chimps would wish to do so a lot more often if they had something precious to carry around. To that end, the researchers offered them some choice nuts.

The chimps were provided with locally available oil palm nuts and imported coula nuts (which the chimps would never ordinarily come across) in the following ratios:  only oil palm nuts, mostly oil palm nuts but a few coula nuts, and a few oil palm nuts but lots of coula nuts. In addition, the chimps were supplied with stone tools suitable for opening the nuts.

The chimps were much more eager to transport coula nuts than oil palm nuts, which presumably they could eat any old time.  When coula nuts were present, the chimps were four times as likely to spend time walking on two legs, a posture that allowed them to carry twice as many items as they could when using their hands to walk.  No surprises there.

The authors postulate that it was the desire to collect and hoard rare items that drove our ancestors down the path of bipedalism. Could that be the case? Consider that Ardipithecus ramidus, an arboreal creature living over four million years ago, was also bipedal.  Did it carry items from one tree to the next? Or perhaps, as has been suggested, hold onto items in order to give them as gifts?

I don’t doubt that the ability to carry objects played a critical role in our evolution.  However, I suspect that more explanations for bipedalism will be found, especially if we can trace the rise of upright walking even further back in our history.  

Wednesday, April 25, 2012

Just for fun: Scistarter

Want to do your part to advance science but don't have access to a supercollider or DNA sequencer?  Have I got the website for you.   Check out Scistarter.  

Researchers create an account specifying exactly what sort of help they'd like.  This can range from taking pictures of local flora to solving puzzles online and everything in between.  The tasks are divided up by topic (insects, health, chemistry, etc.) and by location (things you can do at home, things you can do in the car...). Then volunteers of all ages simply sign up for the job they find most interesting.

There's definitely something for everyone.

Tuesday, April 24, 2012

Honeybee jobs may depend on miRNAs

There are a variety of occupations within a colony of honeybees (Apis mellifera). The best known is that of queen, a position that is held by one individual from birth to death. The rest of the work details are sorted by age rather than aptitude. All bees start out caring for larvae (nurse bees), progress through food preparation, go on to maintain and protect the hive and finally, if they live long enough, become foragers collecting nectar and pollen.

It turns out that age isn’t the only thing distinguishing nurse bees from foragers.  Yehuda Ben-Shahar of Washington University, St. Louis and his colleagues have shown that different bee work assignments are associated with different levels of specific non-coding microRNAs (miRNAs). These snippets of RNA, usually just over 20 nucleotides long, are known to play important roles in regulating gene expression. In bees, they appear to be involved in the progression from one task to another.

The scientists were able to use information from the previously sequenced honeybee genome to identify 97 miRNAs in the heads of honeybees. A few of these miRNAs were present in different amounts in foragers versus in nurses. This held true even when colonies were artificially manipulated to cultivate exceptionally old nurse bees, indicating that the differences were a function of behavior rather than being strictly due to age.

Even more interesting, many of the miRNAs were present only in the brains of eusocial insects (colony insects such as bees, ants and termites). The researchers identified four miRNAs that are present in various species of bee, but not in solitary wasps. Taken together, these data suggest that miRNAs may have played a role in the evolution of the division of labor that is the hallmark of eusociality. 

Monday, April 23, 2012

Jurassic marine reptiles did not explode

Here’s a question you’ve probably never asked yourself: did extinct marine reptiles regularly explode after death? Thanks to the efforts of Achim Reisdorf of Universität Basel and his colleagues, you can rest assured that the answer is no.

The exploding reptile hypothesis was based upon the fact that the fossil remains of marine tetrapods known as ichthyosaurs are often found ‘disarticulated’. That is, they seem to have suffered from some sort of internal disruption. For example, female ichythosaurs have been found with embryos scattered around outside their bodies.


Ichthyosaur female with scattered embryos outside of the body of the mother.
Credit: UZH.

The idea of dead animals exploding isn’t as far fetched as it sounds. Intestinal bacteria can quickly bloat carcasses with putrefying gases to the point where any stress on the skin can result in an explosion of fluid and even internal organs. The authors include some vivid imagery of people running from an exploding whale that someone had the misjudgment to prod too abruptly.

An important point to remember is that the whale in question was located on the shore. At depth, the pressure of the water would have been great enough to prevent any such explosion. The authors calculated that the amount of intestinal pressure within decaying ichythosaurs could not have overcome the water pressure at the depth at which they were found. Therefore, the reptiles could not have exploded.

So what did cause the ribs and embryos to be strewn about? One possibility is that sediments crushed the bodies, and then currents moved the incompletely buried pieces about.

Saturday, April 21, 2012

People who pluck out their own eyes are psychotic

But you didn’t really need me to tell you that, did you?  Conventional wisdom in psychiatry states that self-enucleation (removing one’s own eye, also known as oedipism or auto-enucleation) is the result of either sexual or Christian guilt.  Matthew Large from the University of New South Wales and Olav Neilssen from the University of Sydney have now set the record straight.  Self-enucleation is in fact a symptom of psychosis, especially schizophrenia.

The authors reviewed the published case histories of patients who had severely damaged or removed their own eyes.  Sexual or religious guilt was a factor in only a quarter of the cases.  Delusions, such as that other people were using their eyes for nefarious purposes, played a much greater roll.  In addition, the unfortunate perpetrators of self-enucleation come from a variety of ethnic and religious backgrounds.  In other words, only a subset of the patients surveyed had any familiarity with either Oedipus or the Gospel of Matthew.

To be clear, this is an exceedingly rare condition.  The authors estimate that it afflicts about one out of every 30 million people each year.  If caught before permanent damage is done, sufferers can be managed with medication and close observation. 

No pictures with this post.  You’re welcome.

Friday, April 20, 2012

Tax day may affect your driving

Here’s something I wish I’d known a few days ago. According to Donald Redelmeier and Christopher Yarnell of the University of Toronto, the number of fatal road crashes increases on U.S. income tax day, which falls around April 15th.

The researchers used three decades of fatal crash data, provided by the National Highway Traffic Safety Administration, to reach their conclusion. They compared the number of crashes on income tax day with the number of crashes one week before and after (this year, April 10th and 24th). Thus, all data was for the same season and day of the week.

Over the thirty year span, an average of 13 extra people died on the roads each year on tax day than do on other days. This increase in fatalities is comparable to that of Super Bowl Sunday, which occurs at the beginning of February.

So why is tax day so dangerous? One possibility is that tax day is extremely stressful for many people. Also, people may be more distracted or sleep deprived if they’ve had a late night of filing. They may be more irritable or less patient with other drivers or pedestrians. Whatever the reason, people clearly are not at their best on tax day and it shows in their driving.

Thursday, April 19, 2012

Taking Fido to work

My dog doesn’t usually take an interest in my blogging activities, other than to suggest that my time would be better spent throwing a ball. This time, she was all for my getting to work on this post. Randolph Baker and his colleagues from Virginia Commonwealth University published a study on the benefits of bringing one’s dog to work.

The researchers recruited three groups of employees at a company (Replacements, Ltd) that permits dogs in the workplace. Eighteen people routinely brought their dogs to work (DOG), thirty-eight had dogs but didn’t choose to bring them, and nineteen had no pets. During the four-day study, subjects were instructed to take saliva samples first thing every morning so that cortisol levels (an indicator of stress) could be measured. They were also issued pagers reminding them to complete stress surveys four times each day.

Members of the DOG group brought their dogs to work on Tuesday and Thursday, but left their dogs at home on Wednesday and Friday. The other two groups did not bring any pets to work on any of the study days.

Of the three groups, the lowest stress levels were seen among the people in the DOG group on the days their dogs were with them. People who left their dogs at home had the highest stress levels, and that stress increased as the day wore on. There were no significant differences in morning cortisol levels among the different groups.

Overall, bringing dogs to work seemed to have a net positive affect. It helped the dog owners and didn’t detract from the work environment for non-pet owners. However, it’s important to note that only self-reported stress levels increased. The cortisol levels did not indicate any stress differences even on days when dog owners anticipated having to leave their pets at home. 

Also, on a typical day, Replacements, Ltd has 550 people and 20 to 30 dogs on the premises. All the study volunteers had worked there for an average of ten years, suggesting that they were well accustomed to having dogs around. It would be interesting to see how non-pet owners would react to the sudden introduction of dogs to their workplace.

Wednesday, April 18, 2012

Just for fun: 1000 Days of Infrared Wonders

The Infrared Array Camera (IRAC) on NASA's Spitzer Space Telescope has been recording images for the past 1000 days.  The top ten images, as selected by IRAC team members, can be found here.

Here's just one example:

After a long life of hydrogen-burning nuclear fusion, stars move into later life states whose details depend on their masses. This IRAC image of the Helix Nebula barely spots the star itself at the center, but clearly shows how the aging star has ejected material into space around it, creating a "planetary nebula." The Helix Nebula is located 650 light-years away in the constellation Aquarius. This image was taken during Spitzer's warm mission. 
Credit: NASA / JPL-Caltech / J. Hora (CfA) & W. Latter (NASA/Herschel)

Tuesday, April 17, 2012

Using fire a million years ago

The ability to not only take advantage of fire but to produce and control it may be the most important technological advance of all time. Yet there’s no consensus on how long ago our ancestors acquired this skill. As early as 1.9 million years ago (Mya), Homo erectus showed signs of relying on a diet of cooked food, as indicated by molar size and body mass. However, physical evidence of fire from that time period is scanty.

Now, Francesco Berna from Boston University and an international group of colleagues have found actual burned food remains dating from 1 Mya in Wonderwerk Cave, Northern Cape Province, South Africa. I’d be quite pleased if this location turned out to be the birthplace of cooking. Wonderwerk Cave does sound like a place where things are magically delicious.

In any case, the anthropologists found evidence of burned plants and bone at the site.  Unlike other examples of early fire, the location of the samples within the cave precludes the possibility that they were the result of wild fires. The positioning of the scraps was also incompatible with being swept into the cave by wind or water.  In other words, the items were deliberately burned right there.

Many of the 1 Mya fragments collected were microscopic. Needless to say, it can be challenging to gather evidence that you can’t see. Random sweeps through other promising sites could set the date of earliest fire usage even further back.  

Monday, April 16, 2012

Cell phones and brain development

Hugh Taylor and his colleagues from Yale University reported that cell phone usage during pregnancy affected the brain development of baby mice. I have to say, I’m not convinced.

The researchers attached silenced cell phones to the cages of 33 pregnant mice and left them there for their entire pregnancies (17 days). 42 pregnant mouse controls had deactivated phones attached to their cages. Their combined 161 offspring (82 from exposed moms, 79 from controls) were tested at 8, 12, 16 weeks to see how much time they spent exploring novel objects, how much anxiety they felt and how hyperactive they were.  In case you’re wondering, as I was, how you can tell if a mouse is anxious, you watch how long it’s willing to stay in a lighted compartment. Hyperactivity can be judged by counting the transitions from one compartment to the next.

Cell phone-exposed babies had slightly less anxiety but spent less time exploring new objects, which the authors suggest was due to having poorer memories. They also exhibited more hyperactivity than the controls. In addition, there were some slight differences in neuronal activity between exposed baby mice and controls.

Before you throw away your cell phone and start communicating by semaphore, here are a few things to consider.  First and foremost, the authors never actually measured the amount of radiation the mice were receiving.  As Andrew Wood of the Australian Centre for Radiofrequency Bioeffects Research noted, the phones might have been putting out next to no radiation if they were simply left on but not used. In that case, the entire suite of results is nothing but an artifact. That is, the researchers weren’t measuring what they thought they were measuring.

Even if the baby mice were exposed to radiofrequency radiation and it was responsible for their behavior, that still might not translate into a problem for humans. For one thing, the baby mice were exposed to an activated phone for their entire gestation. I’m pretty sure no human mother has used her cell phone for over six thousand straight hours. Second, the phones were mere centimeters from the mice at all times. If you strapped a phone directly to your pregnant belly it would probably be further away from your baby’s head than the phones were from the baby mice.

All in all, I don’t find these results particularly compelling or alarming.  But I’m neither a doctor nor a pregnant woman.  If you want to be safe, I suppose you could refrain from using your cell phone as a girdle.    

Sunday, April 15, 2012

Bees self-medicate with resins to fight fungal parasites

Michael Simone-Finstrom of North Carolina State University and Maria Spivak of the University of Minnesota have found that honey bees self-medicate with plant resins to ward off fungal parasites. This may not seem that unusual until you consider that the bees aren’t doing this by ingesting or applying the resins to themselves. Instead, they incorporate the resins into the structure of their hive, thereby medicating the entire nest.

Over three summers, the researchers exposed colonies of honey bees to fungal parasites that cause the rather unfortunate sounding chalkbrood disease. As the name suggests, this disease affects bee larvae, not the adult bees that do the foraging. Nevertheless, adult bees living in infected hives collect more plant resins than those residing in uninfected hives. Thus, the adult bees responded to a health threat for the whole colony by changing their habits.

Bees collect plant resins and turn them a substance called propolis, known to have anti-bacterial and anti-fungal properties. Wild bees often line and repair their nests with propolis.  However, the honeybees that Simone-Finstrom and Spivak were studying did not simply incorporate the same resins into every nest as a prophylactic measure against infection. They actively foraged for protective resins as they needed them. This is the very definition of self-medication, even though it’s applied to the colony as a whole.

To be clear, it’s only a very small subset of bees that collects resins regardless of the state of the nest. The vast majority of foragers continue to bring back pollen and nectar. I’d love to know how those few bees 'decide' to switch over to making propolis.

Saturday, April 14, 2012

Coming soon—the tunnel plug

Cities all over the world rely on giant tunnels for transporting goods and people.  You may know these tunnels as ‘subways’. These mass transit systems are great for travel and commerce but terrible for containing floods. Engineers worry that flooding or the release of dangerous gases in a subway tunnel could spread unstoppably throughout an entire city.

To contain such a flood, researchers from the Science and Technology directorate at the Department of Homeland Security have developed a ‘tunnel plug’.  This enormous inflatable cylinder can be stored at strategic locations within the tunnel. Should the tunnel need to be sealed off, the plug is moved into place and filled with either air or water until it’s large enough to seal the hole.

Designing such a plug was quite an engineering feat. For one thing, the empty bag had to be small enough to store out of the way and light enough to quickly maneuver into place. Even more importantly, the expanded plug had to be tight enough to prevent any leakage, yet flexible enough to fit around the many pipes, tracks and ledges that make up the circumference of a subway hole. And of course, the plug had to be able to withstand the pressure of a tunnel full of water barreling towards it.

After several attempts, a successful prototype was developed. The engineers were able to inflate the plug inside a test tunnel where it sealed off the equivalent of a large tunnel flood.

The plug uses high strength fabrics to withstand the pressures of a flooded tunnel.
Photo by ILC Dover.

Friday, April 13, 2012

Holding something makes people think other people are holding it too

There’s an old saying that if you’re a hammer, every problem is a nail.  In other words, our perceptions and abilities color how we view the world around us.  In a rather chilling validation of this aphorism, Jessica Witt of Purdue University and James Brockmole of the University of Notre Dame have found that wielding a gun makes people think other people are doing likewise.

To test this, the researchers showed 34 student volunteers a variety of scenes, some of which included a person holding a gun (though not aimed at the screen) and some of which included someone holding a neutral object. The volunteers held either a WII gun or a foam ball and were instructed to raise the object if they thought the person in the image held a gun and lower it if the person did not hold a gun (these directions were reversed in other trials). The students were more likely to think they saw a gun even when one was not present if they themselves were holding a gun.

In a second experiment, 38 volunteers viewed images of people wearing ski masks and brandishing either a gun or a shoe directly at the camera. This time, each volunteer went through all the images while holding the gun and repeated the exercise holding the foam ball (or vice versa). Again, people were biased to see a gun while holding a gun themselves.

In another experiment, 40 student volunteers were run through the same images as in the first experiment, all while holding the foam ball.  This time, a real but non-functional pistol was placed next to the computer monitor of half the participants. To be clear, at no point did the subjects handle the guns. Having the gun in full view did not bias participants to see more guns in the images.

These data suggest that it’s the physical handling of the gun that makes people more likely to think other people have guns as well. But does this apply to objects other than guns?  I’m glad you asked.  In the final experiment, 44 volunteers were shown the shoe vs. gun images from experiment two, but this time they were holding either a ball or a shoe.  Surprisingly, holding a shoe made people more likely to see a shoe! It turns out that there’s nothing special about guns that elicits this reaction.  We just have a tendency to think other people are carrying whatever we’re carrying.  Most of the time, this inclination is benign, but it can have tragic consequences when firearms are involved.

Thursday, April 12, 2012

Lacerations during angioplasty

Every once in a while I choose a story for no other reason than that a headline amuses me.  This is one of those occasions.  The title was “Tears during coronary angioplasty: Where are they and how do they affect patient outcomes?”  If you read that the way it was intended, you expected to find out whether a laceration in an artery is a bad thing.  If you’re me, you wondered whether it was the doctor or the patient who was crying.

In reality, Rajesh Pradhan and his colleagues at Thomas Jefferson University Hospital were studying the effects of arterial ripping during angioplasty. Angioplasty is the technique of mechanically widening arteries, often by threading inflatable balloons through the effected area. Sometimes the artery is torn during this process, an event that used to require a quick trip to the operating room for repair.  However, according to the doctors, gashes can often be repaired without further incisions by using stents.  The researchers also figured out which arteries were most likely to dissect in the first place.

All in all, it was good news for people who need angioplasty.  No need for weeping.

Wednesday, April 11, 2012

Just for fun: SciShow

There's another great science youtube channel in town:  SciShow.  Hank Green narrates these short vignettes about a diverse range of scientific subjects.  Here's his offering on the Higgs Boson.  Enjoy!

Hat tip:  Dispatches from the Culture Wars.

Tuesday, April 10, 2012

Beware of the order of symptoms

Using the internet to self-diagnose is becoming more and more common. Who hasn’t checked a symptom or two online? Virginia Kwan from Arizona State University and her colleagues from that and other institutions have found that people can come to very different conclusions about their health based on the way the online information is presented.  Specifically, the order of the listed symptoms seems to be critical.

If you search cancer information web sites like (the National Cancer Institute, NCI), you find a mix of symptoms, some mild and general, and some rare, severe or specific.  For example, among other symptoms for bladder cancer, the NCI includes finding blood in your urine and feeling an urgent need to empty your bladder.  How many people have never experienced the second symptom? Obviously the first symptom is much more specific and unusual.

Kwan and her colleagues gave students a checklist of symptoms about a fictitious type of thyroid cancer (dubbed isthmal cancer).  Each student was presented with six possible symptoms for the disease but in three different orders: general then specific, specific then general and alternating.  An example of a general symptom was shortness of breath whereas a specific symptom was pain in the throat or neck.  The students were asked to check off all the symptoms that applied to them, and based on their list, decide whether they might have the disease. I hope none of these students were already hypochondriacs, because if so, this study certainly didn’t do them any favors.

The students who received the alternating checklist were the least likely to think they had isthmal cancer.  The scientists hypothesized that the subjects with the other two checklists were more likely to check several items in a row (because the general symptoms were all clumped together). This in turn may have made them more likely to think they fit the pattern of having the illness. Interestingly, when the number of possible symptoms was increased to twelve, the order of the symptoms had little effect on whether people thought they were sick. Perhaps there were enough unchecked symptoms to make them realize they probably didn’t have cancer.

So how should online medical resources present their information?  According to the authors, that depends on the mission of the site.  If the goal is to get everyone in for a screening or vaccine, the website might want to make a short list of symptoms with the most general ones grouped together.  If, on the other hand, the goal is to discourage unnecessary medical interventions, websites should have long lists of symptoms or alternate general and specific symptoms.    

Monday, April 9, 2012

Super-fast planets

Over the past few decades, cosmologists have theorized about and then confirmed the existence of ‘hypervelocity’ stars.  These are stars that zoom outward at up to 30 million miles per hour.  To put that in perspective, the sun circles the Milky Way at about 500,000 miles/hour and the space shuttle (RIP) could go up to 18,000 miles/hour. To date, at least sixteen such speedy stars have been identified.

During the same time span, hundreds of exoplanets have been discovered.  In fact, many astronomers now believe that nearly every star has at least one planet.  I think you can see where this is going. Idan Ginsburg, Abraham Loeb and Gary Wegner of Dartmouth College have proposed the existence of hypervelocity planets.

Both hypervelocity stars and planets may have the same origin: a binary star system that strays too close to a massive black hole. The two partner stars are ripped apart and one is sent careening out of the galaxy while the other is held hostage by the black hole’s gravitational forces. The escaping star would carry along any orbiting planets it might have, also at high velocity. Planets orbiting the captured star could be sheared off and thrown out of the galaxy as high-speed rogue planets.

Loeb suggests that these planets might not be without their uses, envisioning:
Travel agencies advertising journeys on hypervelocity planets [that] might appeal to particularly adventurous individuals.    

Sunday, April 8, 2012

Oxygen ions detected in the upper atmosphere of Dione

Comparison of Earth, our moon and Dione.
Dione is an icy moon orbiting Saturn.  The Cassini spacecraft that is currently investigating Saturn and its moons has found molecular oxygen ions (O2+) in the upper atmosphere of Dione.  What this does not mean: there could be life on Dione.  I’m not saying there can’t be life on Dione, just that this new information doesn’t sway the balance one way or the other.  What it does mean: life is not required to create abundant amounts of atmospheric oxygen above icy moons.

Robert Tokar and Michelle Thomsen from Los Alamos National Laboratory and their colleagues from six other institutions in the U.S. and U.K used the Cassini Plasma Spectrometer to identify molecules present in Dione’s atmosphere and to determine where those molecules came from. In effect, the cosmologists have identified a way to create O2+ and other forms of oxygen without resorting to photosynthetic organisms. Here’s how it works.

Dione is covered with water ice (H2O). Like all of Saturn’s moons, Dione is subject to a constant storm of charged particles spewing out from Saturn’s magnetosphere. These high-energy particles slam into Dione’s surface and throw a cascade of oxygen molecules high up into the atmosphere.  This phenomenon, called ‘sputtering’, is surprisingly effective. In fact, the concentration of oxygen ions in Dione’s upper atmosphere is similar to the amount found high above the Earth, though obviously our oxygen has a different origin. 

If you are a regular reader of this blog, you’ll know that I include a relevant video with some frequency.  This article is no exception, and the video below is from astronomy fan, isaworld2012.  I admire her enthusiasm, although the symbol for oxygen is not zero.

Saturday, April 7, 2012

To improve memory, put failure in context

Can working memory be improved by influencing a person’s attitude? According to Frédérique Autin and Jean-Claude Croizet of the Universite de Poitiers, the answer is yes. The researchers put some sixth graders through some mental challenges to test this point.

Eleven year old kids were divided into three groups. Two thirds of the kids were given a set of anagrams that were so difficult none of the children were able to solve any of them in the allotted time.  Of those, half were subsequently given a pep talk about how failure in no way reflects on one’s abilities or intelligence and is in fact a sign of learning. A third group wasn’t given the anagrams at all. All the children were then given a working memory test.  Those students who had been told that experiencing difficulty with a problem was normal had slightly better working memories than the students who hadn’t had their failures reframed or hadn’t done any anagrams. In fact, the kids who had their failure at solving anagrams reframed into a positive experience did even better at subsequent memory tests than kids who had solved easy anagrams.

When the kids were asked to decide how well a series of traits described them, those who had had their difficulties reframed were quicker to reject negative attributes and to rank themselves as being competent and good. To be clear, the researchers weren't simply buffing up the students' self esteem by telling them how great they were.  They were merely explaining that failure is a normal part of learning.  The kids drew their own conclusions about themselves.

Friday, April 6, 2012

Supermarkets can affect weight

A team of French scientists plus their colleagues from Australia, the U.S., Canada and Sweden tested whether the location where people buy their food can affect how much they weigh. Somewhat surprisingly, the answer is that it can.

The researchers surveyed over 7000 Parisians as they went about their normal food shopping for a year. During that time, the participants used over 1000 different supermarkets. It was noteworthy that only 30% of shoppers regularly used the closest supermarket to their homes, and only 11% stayed within their neighborhoods. This means that researchers can’t make any assumptions about what kinds of foods are being consumed based on neighborhood shops and restaurants.

After accounting for factors such as socioeconomic status, people who shopped at the same store were more similar in body mass index (BMI) and waist circumference (WC) than people who lived in the same neighborhood. In particular, shopping in a discount store was associated with a higher BMI and WC. Traveling further to reach one’s primary supermarket was also associated with greater BMI and WC.

I should point out that the differences were not large. Changing from one supermarket to another is not going to greatly affect a person’s health. However, health care professionals may want to keep these data in mind when designing educational campaigns.

Thursday, April 5, 2012

Perimenopausal memory loss? Not so much

I’m sure you’re aware that menopause is the cessation of ovulation that occurs when a woman reaches a certain age, usually her late forties or early fifties.  What you may not know is that a woman can experience a number of unpleasant symptoms, including hot flashes and insomnia, for up to ten years prior to her last period.  This stage is known as ‘perimenopause’ or ‘menopause transition’.

One of the commonly reported symptoms of perimenopause is memory loss.  But is this a real effect or just anecdotal?  To find out, Miriam Weber, Mark Mapstone and Jennifer Staskiewicz from the University of Rochester and Pauline Maki from the University of Illinois at Chicago put 75 perimenopausal women through their mental paces.

The women, none of whom had any history of neurological disease, were given a series of memory challenges.  Some examples include being asked to repeat back increasingly long strings of numbers both forwards and backwards, to name as many items in a category as possible (animals that begin with the letter F) and to identify objects that had been cut into pieces.

Prior to taking these tests, the woman were asked to assess how forgetful they were, how well they thought their memories worked, and whether they suffered from anxiety or depression. Hormone panels were taken on test days, which were scheduled to fall between day four and seven of each woman’s menstrual cycle.

While 67% of the women claimed to have suffered from some degree of memory loss, most of them did not in fact have any memory deficits. That is, they performed as expected on almost all the tests. Although the women did a bit worse than expected on a few of the challenges, because they had not been tested before they became perimenopausal, it’s difficult to know whether this indicates any real decline. There were no correlations between hormone levels and cognitive function either.

So it doesn’t look like transitioning into menopause is sufficient to wreak havoc with women’s memories, despite perceptions. You can decide for yourself whether to celebrate that news or mourn the loss of a darned good excuse.    

Wednesday, April 4, 2012

Just for fun: Ocean currents

Data visualizers at NASA's Goddard Space Flight Center put together the following animation of surface ocean currents.

Hat tip: Not Exactly Rocket Science.

Tuesday, April 3, 2012

Message by Neutrino

Daniel Stancil from North Carolina State University and more than a hundred colleagues from all across the globe have sent the world’s first neutrino message.  That is, they sent a message composed solely of subatomic particles called neutrinos, rather than of electromagnetic waves or paper.

Communicating by neutrino certainly has advantages.  For one thing, neutrinos are unimpeded by physical objects. That means that if you want to send a message to the other side of the Earth, you can just aim your neutrinos straight through the ground. No need for satellites or connecting cables. We’d never have to wait for our Mars rovers to be on the right side of the planet to send them instructions.  Also, because neutrinos are virtually mass-less, gravity has little affect on them. They just keep going in a straight line regardless of what’s in their path.

Unfortunately, you need some heavy-duty equipment to send a message by neutrino, including a particle accelerator at one end and an extremely powerful detector at the other. Needless to say, you won’t be trading in your mobile phone anytime soon. 

Thus far, the researchers have only sent a single word, which fittingly enough was ‘neutrino’. They used a binary code of firing and not firing pulses of neutrinos to represent each letter, kind of like the dots and dashes used in Morse code.  It took them over two and a half hours to send and decode that message and achieved an overall data transmission rate of 0.1 Hz. To put that in perspective, you’re probably reading this on a device that's at least a million times faster.  As the authors admit, “significant improvements in neutrino beams and detectors [are] required for practical applications.”    

Monday, April 2, 2012

Doubts cast on collision theory of moon formation

The prevailing theory for how our moon formed is that an enormous collision between the early Earth and a Mars-sized object blasted it into space. If true, much of the substance that makes up the moon should come from the Earth, but a sizable chunk should have originated from the other planetary object, dubbed Theia. Surprisingly, Junjun Zhang and her colleagues from the University of Chicago have found that this is not the case. Essentially all of the moon’s material appears to have come solely from the Earth.

How did the cosmologists reach this conclusion? They compared the ratios of isotopes (atomic variations) of titanium found both on the Earth and in samples brought back from the moon. Different objects throughout the solar system have different ratios of these isotopes. For example, asteroids that have been collected on Earth have highly varied titanium isotope signatures. It’s extremely unlikely that Theia would have had the exact same ratio of titanium isotopes as Earth. Therefore, if the moon truly were a child of their union, it should contain a titanium ratio somewhere between the two.

That’s not what the researchers found at all. Instead, the titanium ratio of the moon is virtually identical to that of the Earth. This strongly suggests that all of the material in the moon came from the Earth and none of it came from the hypothetical Theia.

Unfortunately, without Theia colliding into the Earth, there isn’t a good explanation for how the moon got here. Other hypotheses, such as that the moon spun out of a rapidly rotating Earth or that the moon was a free-floating entity that got captured by Earth’s gravity, have serious flaws. Perhaps Theia was involved but didn’t contribute any material to the building of the moon. This doesn't seem particularly likely either.

I guess it’s back to the drawing board for moon formation theorists.