A Sense of Science

Oct 18

Slime Molds: Pretty, Smart, and Hungry

Ancient, mysterious, and sometimes strangely beautiful:  slime molds are a kind of soil-dwelling amoeba that spend part of their lives as plain old single-celled organisms.  However, they can also band together to form fantastically alien-looking forms like those here.  Some can crawl.  Some have beautiful colors.  And they are all excellent at finding their way to the food.  Case in point:

In 2000, Japanese researchers placed Physarum polycephalum — the name means “many-headed slime mold” — in a maze, along with two blocks of food. It extended its tendrils down the corridors of the maze, bending around curves, reaching dead ends and then backing out of them. After four hours, the slime mold was feasting on both blocks of food.

Another researcher takes a slightly more whimsical approach:

 … a favorite hobby is challenging them to build highway systems. In 2010 he and his colleagues placed a slime mold in the middle of a map of Spain and Portugal, with pieces of food on the largest cities. The slime mold grew a network of tentacles that was nearly identical to the actual highway system on the Iberian Peninsula.

Oct 08

What Science Says About Some Common Food Myths

A recent post on Lifehacker made my little scientist heart go pitter-patter.  The authors take on 10 common food myths and then give actual scientific explanations of why they’re not true.  For instance?  

What I loved about this article was that it was obviously written by scientifically-minded folks.  They properly referenced everything, they even (mostly) linked to some primary sources (ie, actual experiments that had been done to test the hypothesis about wooden vs. plastic cutting boards).  

Even better?  They gave an awesome plug at the end for doing your own research about diet claims. They also gave an excellent link to a Cleveland Clinic page about common sense ways to judge the soundness of nutritional advice.  The questions listed there are good to keep in mind for any health/scientific advice you might hear, on or off the internet..

(10 Stubborn Food Myths That Just Won’t Die, Debunked by Science - via Lifehacker)

Oct 06

One-Dose Contraceptives…For Cats, At Least

Veterinarian Dr. Judy Levy from the University of Florida has put immunology to work in testing out what could be a breakthrough in controlling the feral cat population.  Her group tested out the contraceptive vaccine GonaCon on laboratory cats (which were subsequently all adopted).  GonaCon works by stimulating production of antibodies to GnRH, a hormone that in turn signals the production of sex hormones, including those involved in sexual behavior and ovulation.  By binding to GnRH, the antibodies induced by the vaccine interfere with GnRH’s activity, preventing the release of these sex hormones. This inhibits sexual activity and the animals will remain nonreproductive as long as sufficient GnRH antibody levels are present.

The vaccinated cats all responded to the vaccine with varying levels of success, but overall the trial was a success.  Dr. Levy found that the vaccine (which was originally formulated for use on deer, but also works on other mammals) was safe and long-lasting after just one dose.

Vaccinated cats had a longer time to conception (median 39.7 mo) compared to sham-treated cats (4.4 mo; P < 0.001). A total of 93% of vaccinated cats remained infertile for the first year following vaccination, whereas 73, 53, and 40% were infertile for 2, 3, and 4 y, respectively. At study termination (5 y after a single GnRH vaccine was administered), four cats (27%) remained infertile.  (Journal of Theriogenology - login required for full article)

Not a bad turn out.  This seems like a promising method of contraception for feral cats.  Granted, it doesn’t have extremely long-lasting effects in all cats, but still, if it makes a female miss even a few breeding cycles, that can be a few litters of feral cats prevented.  GonaCon is also evidently fairly cheap, so it is a cost-effective method of sterilization compared to spaying.

- via Futurity.org

Sep 17

Looking to the Trees: A Young Naturalist and the Fibonacci Sequence

Science is, at its heart, the act of following a trail of questions.  Answer one question, and it will lead to ten more.  Luckily, we can often use the answer to one question to fuel the exploration of the next.  One of the 2011 American Museum of Natural History Young Naturalist Award winners, 13-year-old Aidan, found just this when he took a keen observation about tree branching patterns and used it to design and test a more efficient solar panel array.

Aidan noticed that the spiraling pattern of tree branches was eerily similar among several tree species.  He asked the questions:  is there really a pattern, and what kind of pattern is it?  To find the answer, Aidan took measurements on fallen tree branches and found that he was following in the footsteps of the 18th century naturalist Charles Bonnet.  Bonnet had also observed the tree branching pattern and linked it to the Fibonacci sequence, a series of numbers starting with zero and one where each number in the series is the sum of the prior two numbers (ie, 0, 1, 1, 2, 3, 5, 8, etc.)

Not just satisfied by being right, Aidan (like a true scientist) asked another question:  what was the purpose behind this pattern?  Since leaves are a tree’s way of collecting solar energy, it made sense to ask whether or not the Fibonacci-inspired pattern somehow made the leaves more efficient at this task.

To test this hypothesis, Aidan did an experiment:  he made artificial “trees” in the form of solar panel arrays.  One array he constructed so the panels were all at the same angle and facing the same direction (the way solar panels are conventionally constructed).  The other array had the panels in an elm tree’s spiralling Fibonacci pattern.  Aidan then placed these two arrays in the his backyard and measured their energy output over a few months.

His results?

I compared my results on graphs, and they were interesting! The Fibonacci tree design performed better than the flat-panel model. The tree design made 20% more electricity and collected 2 1/2 more hours of sunlight during the day. But the most interesting results were in December, when the Sun was at its lowest point in the sky. The tree design made 50% more electricity, and the collection time of sunlight was up to 50% longer!

Furthermore, the tree design was able to maintain its output even during the winter solstice, when there was the least amount of light and the Earth’s axis was tilted the farthest away from the sun.  As Aidan points out in his write-up, his results suggest that trees have evolved to use this pattern because it is more efficient, especially under challenging collection conditions, and that solar panel makers might do well to emulate trees when they’re designing collection arrays.

Seeing a young investigator go through the entire scientific method like this warms my science-loving heart.  This is exactly the type of thing that I wish more science education programs would encourage and aid.  

Hats off to you, Aidan and the rest of the Young Naturalist awardees.  Great job!

Sep 09

Natural Gas: Another Day, Another Carbon-Based Fuel?

I found this post by James Hrynyshyn to be very thought-provoking on the issue of natural gas being better for the environment than coal.  Environmental scientists have been busy crunching the numbers on this, and several different points of view have come out about whether natural gas is going to help reduce climate change.  Some say yes.  Some say no.  …And ome say that natural gas will actually be WORSE than coal.

How could that be?  As Hrynyshyn describes:

"…because burning coal releases lots of aerosols that hang about the atmosphere reflecting sunlight, a significant portion of the warming effect of the practice [from carbon dioxide and other emissions] is masked by a cooling effect [from reflecting sunlight]. If we stop burning coal in favor of technologies that don’t involve aerosols, we lose that cooling effect. So, unless the alternative has a really, really low warming effect (something close to zero), we won’t be accomplishing much."

How not much are we talking about?  According to the National Center for Atmospheric Research, (and drawing from the primary paper by Tom Wigley)

… a worldwide, partial shift from coal to natural gas would slightly accelerate climate change through at least 2050, even if no methane leaked from natural gas operations, and through as late as 2140 if there were substantial leaks. After that, the greater reliance on natural gas would begin to slow down the increase in global average temperature, but only by a few tenths of a degree.

…yeah.  That’s a good description of “not much”.

As Hrynysyn points out, this paints a bleak picture for any of the so-called “stop-gap” fuels between coal and zero-emissions power sources like solar/wind/nuclear.

If getting off of coal (and oil to a similar but lesser degree) means we lose a significant cooling effect, then whatever new technologies we choose have to be squeaky clean, not just marginal improvements. Carbon capture and sequestration, for example, will have to function at near-perfect efficiencies of more than 90%, which is a bit higher than what some researchers say is realistic.

The same logic applies to any modest emissions-reduction strategy. If, as seems to be case, we only have a few decades to get with the program, then we don’t have the luxury of time or physics to ease ourselves off fossil fuels. We have to go cold turkey.

A sad thought, as the more I look at how LONG it’s taking us to get with the program (ie, how many wind/solar/nuclear plants are going up in your neck of the woods?), the more I’m afraid that we’re missing the boat.

Aug 20

Exxon Valdez vs. Deepwater Horizon: Microbes Still Do All The Work

The world watched in horror a year ago as the Deepwater Horizon oil spill spread a dark stain over the Gulf of Mexico.  The media eagerly reported oil and dead animals on the beaches of the southern US, but there was great uncertainty over what the release of that much oil (approximately 779 million liters) would do to the Gulf’s ecosystem.  BP, the EPA, and conservationists all had their guesses, but the real answer was that no one knew.  Environmental scientists have studied the biology of oil and other hydrocarbons in the environment, but the Gulf of Mexico’s ecosystem is vast, complex, and, like many ecosystems, difficult to predict.  Additionally, it’s impossible to “do the experiment”:  one can’t exactly create a large-scale oil spill to test one’s predictions.  

However, studies of the environmental effects of oil spills such as Deepwater Horizon and the Exxon Valdez spill in Prince William Sound off the coast of Alaska have taught us much about how ecosystems deal with oil contamination.  A recent publication in Environmental Science & Technology compares and contrasts these two disasters and concluded that in both cases, “oil-eating” microbes like bacteria and fungi were the major players in destroying the released oil.

Oil and other naturally-occurring hydrocarbons leak into the environment in small doses, and certain microbes have adapted to consume these hydrocarbons.  These microbes, already present in the environment, usually survive at low populations.  When oil is quickly released in large quantities, the microbes are presented with a feast.  They reproduce quickly and continue to consume the oil present at ever-increasing rates until the food runs out.

Terry Hazen, microbial ecologist with the Lawrence Berkeley National Laboratory and co-author of the recent EST paper, points out how bioremediation strategies often take advantage of and encourage the microbes’ help.  

“In the case of the Exxon Valdez spill, nitrogen fertilizers were applied to speed up the rates of oil biodegradation,” Hazen says. “In the case of the BP Deepwater Horizon spill, dispersants, such as Corexit 9500, were used to increase the available surface area and, thus, potentially increase the rates of biodegradation.” (via Lawrence Berkeley National Laboratory)

This isn’t to say that oil spills are nothing to worry about.  The toll on animal life (including endangered species which may never recover), as well as the loss of revenue from the affected areas can be tremendous.  Still, it is amazing how self-correcting our environment can be…given enough time.  And oh, you weren’t using that beach/ocean/coastline/seabed/animal population in the meantime, were you?

The original paper,  “Oil biodegradation and bioremediation: A tale of the two worst spills in U. S. history”, is available for free, should you want to exercise your environmental science or hydrocarbon chemistry muscles.

Aug 15

Psychological Pressure, Guilt, and Recanting Domestic Abuse

Imagine you’ve been abused by your spouse.  You’ve been brave enough to call the police, and your abuser has been taken away to be charged.  

Then the phone rings.  It’s your spouse…using their one phone call to call you.

This situation happens more frequently than you might imagine.  

Researchers analyzed such recorded calls between 17 abusers and their victims and found that there was a distinct (and quite disturbing) pattern to the conversation.

“The existing belief is that victims recant because the perpetrator threatens her with more violence.  But our results suggest something very different,” said Amy Bonomi, lead author of the study and associate professor of human development and family science at Ohio State University.

“Perpetrators are not threatening the victim, but are using more sophisticated emotional appeals designed to minimize their actions and gain the sympathy of the victim.”  (via Ohio State University news release)

Bonomi then points out that understanding the type of psychological pressures exerted by accused abusers is important for us to be able to offer counseling to victims.

The steps described include minimizing the abuse (“Did I really hit you that hard?  Do I really deserve to go to jail for ten years for hitting you?  Do you really want that?”), recasting the abuser as the victim (“I’m so depressed here.  It’s terrible.  I MISS you and the kids.”), then, once the abuser has the victim’s sympathy, bonding with the victim to gain the victim’s cooperation in evading prosecution.  This particular stage turns the victim’s sympathy into positive emotion, reminding the victim of the good times and reinforcing their love and solidarity against everyone else who “doesn’t understand them”.  

Anyone who’s been in an abusive/codependent relationship will recognize these tactics.  What’s frightening is that they so often work.  And how 17 different abusers just in this one study all used roughly the same strategy.  What, is there a handbook going around somewhere?

I’ll just leave this post with a link to an article with excellent tips and links for abused and battered partners.  Just feels right.

Aug 11

Tattoos of the Useful Kind

Imagine if, instead of being hooked up to machines to monitor your brainwaves, heart, etc., instead your doctor gave you a tiny patch that could take those readings wherever you were and wirelessly send them back to the doctor’s office?  We have the technology! 

“a team of engineers and scientists has developed a new type of ultra-thin, self-adhesive electronics device that can effectively measure data about the human heart, brain waves and muscle activity – all without the use of bulky equipment, conductive fluids, or glues.” - via the National Science Foundation.

Be sure to check out the (tiny) video in the top right corner, where it shows how the device goes on and comes off.  Its components (bonafide sensors, receivers, wires, etc.) are so tiny and flexible that it goes on and comes off just like a temporary tattoo and can stretch with your skin.

The measuring part works.  They’re still looking into the wireless communication part.  As well as finding a way to power it for more than a day or so.  But still.  Ain’t technology keen?

Aug 10

Crowd Control (or Lack Thereof)

The New Yorker had a fascinating article by John Seabrook about crowd control, crowd deaths, and crowd psychology.  What I found most chilling was the description of what actually physically happens when you are in a dense crowd.    

In fact, a crowd is most dangerous when density is greatest. The transition from fraternal smooshing to suffocating pressure—a “crowd crush”—often occurs almost imperceptibly; one doesn’t realize what’s happening until it’s too late to escape. Something interrupts the flow of pedestrians[….]  At a certain point, you feel pressure on all sides of your body, and realize that you can’t raise your arms. You are pulled off your feet, and welded into a block of people. The crowd force squeezes the air out of your lungs, and you struggle to take another breath.

John Fruin, a retired research engineer with the Port Authority of New York and New Jersey, is one of the founders of crowd studies in the U.S. In a 1993 paper, “The Causes and Prevention of Crowd Disasters,” he wrote, “At occupancies of about 7 persons per square meter the crowd becomes almost a fluid mass. Shock waves can be propagated through the mass sufficient to lift people off of their feet and propel them distances of 3 m (10 ft) or more. People may be literally lifted out of their shoes, and have clothing torn off. Intense crowd pressures, exacerbated by anxiety, make it difficult to breathe.” Some people die standing up; others die in the pileup that follows a “crowd collapse,” when someone goes down, and more people fall over him. “Compressional asphyxia” is usually given as the cause of death in these circumstances.

This happens more frequently than you might expect:  rock concerts, sporting events, mass religious gatherings, “doorbuster” sales.  As is mentioned later in the article, the saddest thing about crowd deaths is that the people who are right around you can’t do anything.  They’re being pushed themselves by people ten feet away, who have no idea that you are being suffocated.  Humans are not a social enough (or, traditionally, numerous enough) species to have evolved a way to communicate across long distances in a crowd.  (Ants, for instance, can communicate within a swarm using pheromones.)  With humans, you’re limited to your lungs and hands…which are usually already pinned by the time you realize you’re in trouble.  

Some tips for how to be safe in a pressing crowd, wherever it might be :

Tips provided by Crowd Management Strategies ©2000 (You and the Festival Crowd
Tips provided by Crowd Management Strategies ©2000 (You and the Festival Crowd


Tips provided by Crowd Management Strategies ©2000 (You and the Festival Crowd


Know where exits are in relations to a position in a crowd.
l   Move away from a dense crowd when you have limited mobility.
l   Try to keep your composure, Remain Alert!
l   Do NOT panic.
In a crowd crush surge, try to escape by moving away from the direction of the
l   Do not stop to pick up personal items in dense and moving crowds.
l   Use nonverbal communication to gain attention when noise levels are too high.
If you fall and cannot get up, you may want to cover your head and curl up, bringing
arms and legs close to your body


Know where exits are in relations to a position in a crowd.Move away from a dense crowd when you have limited mobility.Try to keep your composure, Remain Alert!Do NOT panic.In a crowd crush surge, try to escape by moving away from the direction of the crushing.Do not stop to pick up personal items in dense and moving crowds.Use nonverbal communication to gain attention when noise levels are too high. If you fall and cannot get up, you may want to cover your head and curl up, bringing arms and legs close to your body

Aug 07

Physics, Psychology, and Escaping from Zip Ties

Found an interesting practical use of physics and psychology, via the ITS Tactical blog:  How to Escape from Zip Ties.  The videos linked there demonstrate several methods for breaking/slipping out of zip ties, should you find your hands bound by them.  (DISCLAIMER:  These techniques are only for use if you are illegally restrained.  I do NOT endorse escaping if you are lawfully restrained [ie. by the police, etc.].  Seriously.  Just don’t.)

I am sad that I don’t have any zip ties around the house to try this with.

What I found interesting was how these tips made use of physical and social science to keep you free.  Physics, in how the first two videos’ techniques work because you are essentially focussing all the strength of your arms onto the tie to break it.  And psychology because of the suggestion to stay passive (don’t appear likely to try to escape, so you will have the element of surprise when you do) and to offer your hands to a captor in a “preferred” configuration that will be easier to get out of.  That last doesn’t mean you’ll get what you want, but it might give you back a little bit of control, if your captor doesn’t know what they’re doing.

Jul 29

From xkcd today, a sobering and accurate comic on surviving cancer (cover the kiddies’ eyes, it’s got one f-bomb in it):

And that is why actually curing cancer is so hard.  How to pick out those few bad cells from your billions of good ones?  In most cases?  We can’t.  Not yet.  But we are working on it.  

Jul 23

Medieval Armor: Hindrance as Well as Help

That medieval armor was heavy (averaging 66-88lb) goes without saying.  But what effects did it have on a warrior’s energy expenditure?  It LOOKS like it would be exhausting to move in, but just how exhausting was it, and how would carrying that weight in that distribution affect movement?

A recent publication out of the Universities of Leeds, Milan, and Auckland asked just this question.  They dressed volunteers in 4 different types of medieval armor and tested their energy expenditure, breathing, and other reactions while they ran and walked.  Essentially, they found exactly what common sense would predict:  carrying 80lbs of metal makes it harder for you to move.  

We found that the net cost of locomotion (C(met)) during armoured walking and running is much more energetically expensive than unloaded locomotion. C(met) for locomotion in armour was 2.1-2.3 times higher for walking, and 1.9 times higher for running when compared with C(met) for unloaded locomotion at the same speed. [abstract]

When the scientists gave the volunteers an equivalent weight to wear in a backpack, energy expenditure was much lower than when they were wearing the distributed weight of the armor.  The key to this, says the lead researcher, is distribution.

“This is because, in a suit of armor, the limbs are loaded with weight, which means it takes more effort to swing them with each stride. If you’re wearing a backpack, the weight is all in one place and swinging the limbs is easier,” explains Graham. [Futurity.org]

You can actually SEE how hard it is to move the limbs by watching the volunteer’s arm movements in the treadmill video above.  He hardly moves his arms at all.

Jul 18

Arms Race: Venomous Snakes and Their Predators

It’s not every day that you get to see evolutionary pressures at work, but that’s exactly what Sharon Jansa (U. of Minnesota) and Robert Voss (American Museum of Natural History) found when they started studying (of all things) the Virginia opossum.  In looking at opossums’ genetic data, they found an unusually high amount of differences in genes coding for a blood protein called “von Willebrand’s Factor” (vWF).  This blood protein is a target of snake venom, which usually attacks vWF to cause the massive internal bleeding that leads to venom-induced death in snakebite victims.  

Why would opossums have such a huge amount of differences in their vWF gene?  The reason lies in the evolutionary battle that’s constantly being waged by the opossum and the venomous snakes that they eat.  Snake venom proteins also have an incredibly high amount of variation in their genes.   This, in turn, encourages variation in the opossum defenses against that venom (their vWF).  

It’s a classic example of evolutionary pressure, where there’s a clear advantage to having a variety of different genes in the gene pool (variety = fewer opossums dying from eating the local snakes!)  It’s not often that there is that strong an evolutionary pressure (instant death for having the wrong gene will do that!), so seeing a relationship like this between predator and prey is kind of awesome.

Jansa SA, Voss RS (2011) Adaptive Evolution of the Venom-Targeted vWF Protein in Opossums that Eat Pitvipers. PLoS ONE 6(6): e20997. doi:10.1371/journal.pone.0020997

Jul 03

What Drowning Really Looks Like

We all know what drowning looks like, right?  We’ve seen it on TV!  In movies!  People waving their arms and crying out for help!   Unfortunately, that’s not what real drowning looks like at all, and most people don’t even realize it.  

The Instinctive Drowning Response … is what people do to avoid actual or perceived suffocation in the water.  And it does not look like most people expect.  There is very little splashing, no waving, and no yelling or calls for help of any kind.  To get an idea of just how quiet and undramatic from the surface drowning can be, consider this:  It is the number two cause of accidental death in children, age 15 and under (just behind vehicle accidents) – of the approximately 750 children who will drown next year, about 375 of them will do so within 25 yards of a parent or other adult.  In ten percent of those drownings, the adult will actually watch them do it, having no idea it is happening (source: CDC). - Mario Vittone, Drowning Doesn’t Look Like Drowning

Vittone, a marine safety specialist with the U.S. Coast Guard, also says to look for:


Look for these other signs of drowning when persons are n the water:
Head low in the water, mouth at water level
Head tilted back with mouth open
Eyes glassy and empty, unable to focus
Eyes closed
Hair over forehead or eyes
Not using legs – Vertical
Hyperventilating or gasping
Trying to swim in a particular direction but not making headway
Trying to roll over on the back
Ladder climb, rarely out of the water.

Jun 17

Pathogens in Glass

A totally breathtaking look at the form of viruses and bacteria, rendered in glass by the artist Luke Jerram.  Beautiful and scientifically accurate!

This one is T4 bacteriophage, a virus that actually infects bacteria.  Yes, it looks like a little alien lander.  They’ve also got human papillomavirus, too, a virus near and dear my researcher’s heart but totally not as cool-looking as T4 bacteriophage.