Science-- there's something for everyone

Wednesday, February 29, 2012

Just for fun: Bubbles and magnets

San Francisco designer Kim Pimmel played with ordinary soap bubbles, a ferrofluid liquid and some magnets to create the following visual ballet.

Hat tip:  Jennifer Ouellette.

Tuesday, February 28, 2012

Fish can estimate

Humans have at least two distinct ways of evaluating the numbers of objects.  For very small numbers (usually no more than four or five) we can immediately tell how many items there are without counting.  For larger numbers, we can compare relative amounts (a group of twenty is larger than a group of eight). You may wonder if these abilities are among the vanishingly few traits that set us apart from the rest of the animal kingdom.  If so, you would be wrong.  Many other creatures can also compare and contrast numbers, including other primates, dogs, and even guppies.  Yes, fish can estimate numbers.

The two numerical representation systems are referred to as the ‘object-file system’ and ‘analog system’.  Because of the object-file system, we can distinguish between two and three objects with the exact same speed and ease as we can between one and two objects.  The ratio of the objects makes no difference.  However, with larger numbers, the analog system kicks in, and the ratio of objects becomes increasingly critical.  We can tell fifteen from fifty objects at a glance, but not fifteen from eighteen.  Thus, non-human organisms that have both of these systems should also display ratio dependent abilities to discriminate between groups of large numbers but not small numbers.

Christian Agrillo, Laura Piffer and Angelo Bisazza from the University of Padova and Brian Butterworth from University College London compared the numerical acumen of undergraduate students and guppies (insert obligatory joke about both groups being in schools).  The students were asked to compare the numbers of dots flashed on a computer screen, whereas the guppies (an extremely gregarious species) were presented with the choice to associate with a larger or smaller shoal of fellow fish.

Both groups could tell two from three as easily as three from four.  Both groups also distinguished large groups that differed by 50% (four versus eight) more easily than groups that differed by only 25% (six versus eight).  In other words, both guppies and students displayed evidence of having both the object file system and the analog system of estimating numbers.  

There are two possible explanations for this.  Either number sorting ability goes very far back in our evolutionary past, or it has evolved independently multiple times.  It would be interesting to see whether solitary animals also have these abilities.

Monday, February 27, 2012

More than one way to create a placebo

Placebos are fascinating.  For totally inert substances, they have a remarkable ability to alter how we perceive pain.  One hypothesis for how this might work is that the placebo distracts us from our pain.  To test whether this is true, Jason Buhle, Bradford Stevens and Jonathan Friedman from Columbia University and Tor Wager from the University of Colorado compared traditional placebos with mental distractions.  Not only did both methods ease pain, but the results were cumulative, indicating that two different pain-alleviation processes were involved. 

The researchers put 33 volunteers through a rather harrowing set of experiments. On day one, each person performed calibration tests to determine their pain tolerance levels (when exposed to high temperature) and their performance on memory tests.  Over the next two days, the participants performed similar tasks.  Prior to the application of heat, the effected area was covered with a cream that half the participants (placebo) were told was an analgesic.  In reality, no volunteers received any type of medical pain relief.
The subjects were then further divided such that there were four test protocols.  One quarter received what they thought was an analgesic and were asked to do nothing while their arm was subjected to heat, one quarter received the pretend analgesic and were asked to perform memory tests.  The other half of participants knew they were not getting any pain relief in the cream (controls) and were also divided into those performing memory tasks and those doing nothing.

Both groups (placebo and control) reported less pain during the memory distraction tests. Also, the placebo alone outperformed the control.  Thus, either distraction or placebo lowered perceived pain levels.  Interestingly, the greatest benefit was seen in the group that got both the placebo and the distraction.  In fact, the effect was almost completely additive.

Taken together, these results indicate that mental distraction is itself a worthy placebo, but one that functions independently of medical placebos.  Next time you have a painful procedure planned, don’t forget to bring your sudoku along.  

Sunday, February 26, 2012

Dark matter connects galaxies

Dark matter, as the name implies, is an enigma.  We know that nearly a quarter of the universe is made up of this unknown substance.  Only 4.5% of the universe is made of what we normally think of as matter, that is atoms.  Not only do we not know what dark matter is, we’re not even sure where it is.  However, that may be changing, thanks to the efforts of Shogo Masaki from Nagoya University, Masataka Fukugita and Naoki Yoshida from the University of Tokyo.  They used observations of gravitational lensing and computer simulations to find dark matter.  It turns out dark matter connects all the galaxies in our universe.

Gravitational lensing is the distortion in the light from distant galaxies caused by closer sources of gravity, such as nearby galaxies.  You can see that illustrated below.

Missing dark matter located: Intergalactic space is filled with dark matter

The two images illustrate the effect of gravitational lensing. A massive galaxy at the center of the right panel causes the images of the background galaxies (white spots) to be enlarged and brightened.
Image credit: Joerg Colberg, Ryan Scranton, Robert Lupton, SDSS

Dark matter also exerts gravitational effects on normal matter. That’s how we discovered dark matter in the first place.  However, until recently, we didn’t have enough data to see just how much of an effect dark matter was having on galaxies.  Luckily, the Sloan Digital Sky Survey has been steadily capturing images of galaxies for the past decade.  The authors were able to put 24 million galaxy images into their computer simulation.

They found that there is effectively no empty space in the universe.  The distribution of dark matter extends from galaxy to galaxy.  Regions devoid of stars are not devoid of dark matter; it truly seems to be ubiquitous.  Now, if we can only figure out what it is.

Saturday, February 25, 2012

The many uses of nanoparticles

I have a confession to make.  The main reason I wanted to write about the research of João Conde, Gonçalo Doria, and Pedro Baptista of Universidade Nova de Lisboa is that I love the diagram they included in their paper.  Here it is:


Neat huh?  I could stare at that picture for a long time.  But what does it mean?  Basically, it’s a chart of all the ways that nanoparticles (NPs) can be used to combat tumors.  On the right is a tumor embedded within normal tissue.  The tumor and the NPs are magnified on the left.  You can see that NPs are like a Swiss army knife for medical applications.  They can contain anti-sense RNA,  small RNA molecules that interfere with normal gene expression in order to silence tumor genes (top left).  They can deliver a variety of drugs and chemicals through the blood stream to the tumor (bottom right). NPs can be configured to convert specific electromagnetic waves into heat or radiation, effectively cooking tumor cells into oblivion (middle top and bottom, respectively).  They can even be used to optimize imaging of the tumor and surrounding tissue (far right). And best of all, NPs can be targeted so precisely that only tumor cells are affected (bottom left).

NPs are still being investigated to address safety concerns (symbolized on the top right).  Interestingly, it seems that larger nanoparticles (between 10 and 100 nanometers across) are less toxic than smaller ones (particles less than 2 nanometers across).  As more research is done, I’m sure even more uses will be found for these tiny structures.

Friday, February 24, 2012

Regrowing nerves

George Bittner and his colleagues from the University of Texas at Austin may have found a way to reattach severed nerves.  Although only tested in rats, they have every hope that their technique will prove equally successful in humans.

First, why is it so difficult for severed nerves to regrow?  Well, it isn’t for all animals.  Invertebrates are able to reattach severed nerves in a few days.  Mammals are not so lucky.  When one of our nerves is cut or damaged, the nerve axon (the part that reaches out toward a muscle cell or another nerve) dies back in a process called Wallerian degeneration.  It can take over a year for the nerve to grow back, and sometimes the proper connections never get remade.  Invertebrates don’t suffer from Wallerian degeneration, and thus their nerves can simply reattach. 

The researchers used a mix of chemicals to prevent the severed or crushed sciatic nerves of rats from undergoing Wallerian degeneration.  They applied the antioxidant methylene blue keep the axonal ends open and polyethylene glycol to subsequently fuse them.  The rats treated this way showed significant improvement within a week.
The researchers are hoping to begin clinical trials soon. If it works in humans, this would be a stunning breakthrough in treating nerve-damaged individuals.

Hat tip:  The Skeptics’ Guide to the Universe

Thursday, February 23, 2012

Recipe for preventing teen suicide: support, don’t bully

Actually, that recipe seems pretty obvious.  However, in light of recent suicides among the lesbian, gay, bisexual, transgender (LGBT) community, that message seems worth repeating. Suicide is the third-leading cause of death for adolescents, and it’s particularly high for LGBT kids. What can be done about this?

Richard Liu and Brian Mustanski of Northwestern University recruited 246 young people between age16 and 20 who self-identified as LGBT for their study.  The volunteers were assessed at the start of the study and again every six months for two years.  The kids were evaluated for a variety of thoughts and behaviors: thoughts of suicide, depression, impulsivity, examples of self-harming (cutting), sensation seeking, gender nonconformity, hopelessness, and history of suicide attempt. The volunteers also testified to how often and how severely they were victimized specifically for being LGBT and how much social support they received from their families and communities.

Not surprisingly, LGBT victimization and low social support correlated with high self-harm and thoughts or attempts of suicide.  In fact, LGBT victimization was the second greatest predictor of suicide for young people, being surpassed only by previous suicide attempts.

So, to recap, to save teenagers lives, stop bullying them and let them know they are valued members of their community.  Come to think of it, that’s pretty good advice for all people, not just for LGBT kids.

You can watch commentary by the authors below.

Wednesday, February 22, 2012

Just for fun: Visualization Challenge

If there's one thing I love, it's combining art and science.  The folks at Science Magazine put on an annual competition called the International Science and Engineering Visualization Challenge.

This picture was my favorite, and also a people's choice award winner.

Caption: Separation of a Cell, Andrew Noske et al.
In cell division, the cell membrane (blue) stretches, while the genetic storehouses called chromosomes (yellow) split into identical sets. This illustration from University of California and Salk Institute researchers is built up of real image "slices" of a cell caught in the act, assembled into a striking 3-D whole.

And here's the winning video:

You can view a slide show of the winners here.

Hat tip:  David Brin.

Tuesday, February 21, 2012

The last shall be best

Now here’s an experiment I wouldn’t mind participating in.  In an effort to understand whether people rate final experiences more highly than earlier ones, Ed O’Brien and Phoebe Ellsworth of the University of Michigan fed their volunteers a bunch of chocolates.  Mmm…  science!

Fifty-two lucky students were each given five different flavors of Hershey Kisses in random order.  After each sample, the experimenter would say, ‘here is your next chocolate’.  For half the subjects, the statement before the fifth chocolate was changed to ‘here is your last chocolate’. In other words, half of the volunteers were warned that the upcoming chocolate was to be their last one and half were not.

So how did all the chocolates rank?  By a wide margin, people who had been apprised that they were about to receive their last chocolate rated that flavor as the best.  In fact, participants who were notified that the test was about to end rated the entire experiment more highly.  Apparently, everything becomes more pleasurable when you know it’s not going to last.

I’m already scheming to use this knowledge to manipulate myself into getting more enjoyment out of life.  The authors are right on board with this idea.  They suggest, 
Consider the cheaper option during your final visit to a restaurant – it may taste just as delicious as any other.

Monday, February 20, 2012

Correcting false information

It can be exceedingly difficult to disabuse people of false information, with one exception.  Apparently, if you quiz people on something, correct their errors, and then give them the exact same quiz five minutes later, they do better.  This is true even if they had been quite confident about their previously held wrong ideas.   Okay, this isn’t particularly surprising or helpful.  But can people still remember the corrected answers a week later?  This was the question Duke University researchers Andrew Butler and Elizabeth Marsh, and Carnegie Mellon psychologist Lisa Fazio set out to answer.

The scientists gave 50 undergraduate volunteers a series of 120 general knowledge questions.  After each question, the correct answer was given. Six minutes after completing the test (and after performing a brief unrelated ‘filler’ task), half the group was given the exact same test again.  The other half would be given the test one week later.

So how did everyone do?  The average correct answer rate on the initial test was 38%.  This doesn’t say great things about our educational system, given that these were college students.  However, the authors optimistically noted that this low number allowed plenty of room to evaluate improvement.  Alas, the students who retook the test six minutes later showed much greater improvement than those who waited a week.  In other words, by a week later, many of the volunteers had already forgotten the corrections.  Still, the fact that people can retain information for six minutes is better than nothing. 

By the way, yours truly got 78% right on an initial run through the test and 90% one week later.  In my defense, it wasn't always clear what the authors were looking for. For example, one question was: "What causes a bull to become angry and charge during a bullfight?"  I initially answered, 'being prodded with spears' but subsequently learned that the answer was supposed to be 'movements of the cape'.  

Sunday, February 19, 2012

Redrawing the map of blood cell formation

A standard model of blood cell development is shown in the diagram below.

As you can see, the progenitor blood cells (hemocytoblasts) can differentiate into any type of blood cell. After the first step in differentiation (shown in the second highest line), the pathway is fixed so that each cell ends up being either an erythrocyte (red blood cell), leukocyte (white blood cell) or thrombocyte (platelet cell).  At least, that was the thinking until some experiments, led by Ashley Ng of the Walter and Eliza Hall Institute of Medical Research, proved otherwise.

The researchers found that cells (megakaryoblasts) thought to lead solely to the platelet line could in fact give rise to red blood cells.  In fact, many of the progenitor cells had far more flexibility than was previously thought.  Apparently, the production of different types of blood cells within bone marrow is regulated, not at the first step of differentiation, but much later on.  The scientists could even control the blood cell output by applying different chemical signals. Needless to say, this could turn out to be extremely useful.  Being able to boost or deplete specific populations of blood cells could be invaluable in treating blood diseases.

Although this data was only collected in mice, it may very well be applicable to humans.  If so, it changes the entire picture of how blood cells are made and regulated.

Saturday, February 18, 2012

Early detection of autism

Autism spectrum disorder (ASD) typically get diagnosed after the first year of life. This is much earlier than just a few decades ago, but not as early as health care professionals would like. Thanks to new research by Joseph Piven of the University of North Carolina and his colleagues, doctors may be able to push back the diagnosis of ASD to only six months of age.

As part of the Infant Brain Imaging Study, the researchers enrolled babies who had at least one autistic sibling and were thus considered to be at high risk for having ASD themselves.  The babies underwent brain scans at 6 months, 12 months and 24 months.  At 24 months, the children were evaluated for ASD symptoms.  A little over a third of the children ended up having ASD, the rest did not.  Even at six months, there were clear differences in the brain scans between the two groups of children.

The earlier children can be diagnosed with ASD, the more help they can receive during the first stages of their lives. These early interventions can make a huge difference in the progression of the disease.  Piven and his colleagues would like to extend their research to include infants younger than six months, to see just how early ASD detection can be made. 

Friday, February 17, 2012

Honey to the rescue

The bacteria Streptococcus pyogenes can be found all over the skin of healthy individuals.  Normally, it causes few problems.  If the skin is punctured, however, either through surgery or wounding, the bacteria can get inside and wreak havoc.  Luckily, honey may be just what the doctor ordered.

S. pyogenes is particularly deadly when it forms a biofilm.  When free-swimming bacteria, which would otherwise be susceptible to antibiotics, clump together into biofilms, they become distressingly resilient. The cells stick to surfaces with remarkable tenacity and are exceedingly difficult to kill. What’s worse is that S. pyogenes biofilms produce proteins that allow the bacteria to bind to the fibronectin that is prevalent at wound sites. The result can be a chronic wound that refuses to heal.  Thus, disrupting the transition from solitary bacterium to biofilm member can be even more important than the outright killing of bacteria.

Sarah Maddocks and her colleagues from Cardiff Metropolitan University tested the effects of manuka honey (honey made almost exclusively from the Australian/New Zealand manuka, or Leptospermum scoparium) on S.pyogenes.  Manuka honey is high in methylglyoxal, thought to have antibacterial properties.

The researchers found that although it took a solution of at least 40% manuka honey to kill almost all the S. pyogenes in a sample, as little as a 5% honey solution prevented most of the little buggers from congregating into biofilms. In addition, a 20% solution of honey significantly reduced the amount of fibronectin-binding protein made by the bacteria, which resulted in far less wound-attachment.

Will we see nurses slathering honey on their patients’ wounds in the near future?  The authors did use ‘sterile medical grade manuka honey’ for this study, so who knows?

Thursday, February 16, 2012

A cure for Alzheimer’s?

Gary Landreth of the Case Western Reserve University School of Medicine and his colleagues may have found a way to reverse Alzheimer’s disease (AD).  For now, it’s only been tested in mice but clinical studies in humans will hopefully follow.

AD patients of all species accumulate beta amyloid proteins in their brains.  These proteins form plaques that are associated with the cognitive decline seen with this disease. Beta amyloid is naturally cleared from the brain by another protein, apolipoprotein E (apoE).  The bad news is that some people, especially those who draw the short genetic straw, don’t make enough apoE to do the job.

Landreth and his team found that a drug called bexarotene dramatically increases the apoE levels. This in turn leads to an almost immediate decrease in the number of beta amyloid plaques in mice. What’s more, mice treated with bexarotene had greatly improved cognitive functions, including memory.  For example, AD mice that have been given bexarotene happily went back to constructing nests, whereas untreated mice literally didn’t know what to make of the building materials with which they were provided.

Unfortunately, beta amyloid plaques are only obvious at autopsy.  By that time, patients no longer care whether a treatment has potential, and researchers may have had to wait decades to see a result.  Mice make much more convenient subjects with their short lifespans and non-litiginous natures.  Although bexarotene has a good safety record in humans, we won’t know if it does as well in humans until we try it.  

Wednesday, February 15, 2012

Just for fun: Scale of the Universe 2.0

A couple of years ago, I posted a link to the amazing journey Cary and Michael Huang took us all on from yoctometer to Yottameter.  Well, Scale of the Universe Two is even better!  Sorry I couldn't embed it, but believe me, it's worth a look.  Check it out here.

Use the slider to go up or down in size.  You can also click on each picture to get more information about that item.

Screen shot from Scale of the Universe 2
by Cary and Michael Huang.

Tuesday, February 14, 2012

Another use for DNA barcoding

DNA barcoding is a method of identifying to which species an unknown organism belongs.  For example, DNA barcoding has been used to determine whether fishmongers and restaurants are really selling the kinds of seafood they claim to have on offer (much of the time they aren't).  The technique is quite simple.  You sequence a specific section of DNA, most often the mitochondrial cytochrome c oxidase subunit 1 (COX1) gene, and compare what you find with the known COX1 genes of different species.  When you get a match, you’ve identified your specimen.

Researchers from the Centre of Expertise for Rabies and from the University of Ottawa have used DNA barcoding to label bat species in the hopes of also identifying strains of rabies. In Canada, where this study was conducted, about 80 bats are found to be infected with rabies each year. Thirty species of bat indigenous to the United States and Canada have tested positive for rabies.  Needless to say, this can pose a threat to humans, pets, and lifestock. 

Using DNA barcoding, the scientists were able to reassign a few bats to their proper species. As most species of bat harbor a unique variant of rabies, understanding to which species a population of bats belongs can help track the rabies virus as well.

Hat tip:  Karen James.

Monday, February 13, 2012

What do people look for in a tweet?

If you use twitter, you may wonder both why you get a lot of tweets in which you have no interest, and why no one seems interested in your tweets.  Researchers from Carnegie Mellon University, MIT and the Georgia Institute of Technology wondered this as well.  To answer the burning question of what makes a good tweet, they set up a study asking people exactly that.  The results are being presented at the Association for Computing Machinery's Conference on Computer Supported Cooperative Work.

At ‘Who Gives a Tweet’, the scientists collected feedback from 1400 volunteers who offered to rate the tweets of people they were already following.  This being twitter, you won’t be surprised that the researchers got data on close to 45,000 tweets made by 21,000 people in just nineteen days. 

And what did these twitter testers think?  Overall, they liked about a third of the tweets they received and actively disliked about a quarter.  They were neutral about the rest. 

Here’s what distinguished the most liked from the most disliked tweets:  Good tweets were topical, relevant and short.  They were also easier to read, lacking excessive use of #hashtags and @mentions.  They weren’t overly negative or condescending.  Most importantly, they didn’t discuss mundane personal items.  People don’t want to know what kind of sandwich you’re making, but they do want to know what your next project will be.

The study is complete, but you can still go to Who Gives a Tweet and rate a few tweets yourself if you like.

By the way, this isn’t the first twitter study.  Ryan Kelly of Pear Analytics put out this handy graph back in 2009.

Sunday, February 12, 2012

Obesity linked to pain levels

If you needed one more reason to avoid becoming obese, here’s a good one.  Obese people suffer significantly more day-to-day pain than their thinner cohorts.  Arthur Stone and Joan Broderick of Stony Brook University conducted a telephone survey of over a million Americans to come to this somewhat unsurprising result.

Participants, who were randomly selected by the Gallup Organization, were asked about their height and weight, general health, and levels of pain, both over the past year and yesterday.  The researchers calculated body mass index (BMI) from the answers.  Even accounting for medical conditions known to cause pain, the obese group suffered from significantly more daily pain than the normal weight group.  In fact, the more obese a person was, the more likely he was to suffer from daily pain. I should add that the additional pain was not necessarily the kind of skeletomuscular pain you'd expect to see with carrying excess weight.  

Obviously, there’s a huge caveat here.  Because the weights were self reported over the phone, the researchers had no way of assessing how accurate those numbers were.  However, I don’t think that should change the outcome.  If anything, most people tend to underestimate their weight, which would have resulted in more people in the normal group reporting pain. 

Saturday, February 11, 2012

Why I’m not a sprinter

I’m always looking for a good excuse as to why I’m no good at sprinting.  Thanks to the work of Stephen Piazza and his colleagues from Pennsylvania State University, I may have found just the thing.  Apparently, I don’t have the right foot and ankle structure.

The researchers compared the foot length and ankle positions of eight sprinters with eight height-matched not-sprinters.  You won’t be surprised to learn that the sprinters feet had different proportions than the non-sprinters.  Archimedes invented a little tool called ‘the lever’ that explains this quite nicely.  The amount of force needed to use a lever depends on its length and on the position of the fulcrum along that lever. A longer foot coupled with a shorter Achilles tendon gives sprinters a mechanical advantage each time they push against the ground.  

To be honest, I haven’t measured the ratios of my toe bones to my tendons.  I’m quite willing to assume that I would have been a world-class sprinter if it weren’t for my unfortunate draw in the foot genetics pool.  Otherwise, I’d have to fall back on lack of practice, and no one wants that.

Friday, February 10, 2012

How E. coli grows so fast

Even for bacteria, Escherichia coli (E. coli) can multiply at a prodigious rate.  In fact, they can divide faster than they can replicate their DNA.  Although this seems impossible, E. coli have a neat trick for accomplishing this feat.

First, let’s look at how cells normally divide.  In order to duplicate itself, a single-celled organism like E. coli first makes a copy of its DNA, then divides in two.  Each resultant daughter cell receives one copy of the DNA.  You can see an animation of DNA replication below:

It takes about forty minutes to make one complete copy of the E. coli genome.  Therefore, each generation of E. coli should last just under an hour.  Instead, E. coli can divide (under ideal conditions) in as little as 20 minutes.  How is this possible? 

It turns out that E. coli can begin a new round of DNA replication before the previous round is complete. When the cell splits in two, each daughter cell receives a strand of DNA that is already in the process of being copied.  That is, the daughter cell receives DNA that is halfway prepared for the eventual granddaughter cells.

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Replication pattern of rapidly growing E. coli wild-type cells. Cells (yellow) with chromosomes (blue lines) and origins (black squares) are drawn schematically to show the number of replication forks and origins at different stages of the cell cycle. In this example, initiation of replication occurs at four origins at the same time as cell division (bottom). A young cell therefore contains four origins and six replication forks (upper left). As replication proceeds, the oldest pair of forks reach the terminus and the two sister chromosomes segregate. The cell then contains four origins and four replication forks (upper right). Initiation then occurs again at 4 origins and generates 8 new forks giving a total of 12 forks, as cell division approaches (bottom). 

As you can imagine, this requires tight control.  The bacterium can’t divide until it has at least two complete and separate genomes, regardless of how much extra replication is going on.  An international team of scientists led by Matthew Grant from the University of Cambridge has found that specific factors govern just how this occurs.  This might give researchers a better handle on controlling bacterial cell growth.

Thursday, February 9, 2012

New ways to assess infant pain

It can be difficult to assess pain in very young and premature infants.  Simply watching for changes in posture or expression isn't always enough to indicate how much discomfort a newborn is feeling.  Therefore, researchers from University College London were looking for a better way to determine how much pain a baby is feeling.

They used electroencephalography (EEG), electrocardiography (ECG) and electromyography (EMG) to indirectly detect evidence of pain.  These non-invasive devices record electrical activity in the brain, the heart and in muscle, respectively.  Infants were hooked up to the devices and recordings were made of three events: a heel tap with a rubber bung, a touch with a lancet that did not pierce the skin, and a medically required heel lance to collect blood.  EEG, ECG and EMG results were compared for the three events.  The electrical data correlated well with presumed pain levels.

Aside from providing information to people who must care for infants, this study is interesting because it was published in the Journal of Visualized Experiments.  You can watch a video demonstrating exactly how the experiments were conducted, and what the results were.  Warning, the video includes a close up of an infant receiving a heel lance.

Wednesday, February 8, 2012

Just for fun: Checking in with Project Steve

In 2001, a creationist group called the Discovery Institute issued a statement called 'Scientific Dissent from Darwinism'.  It included a purported list of scientists who don't accept common descent as the explanation for the diversity of life on Earth.  On closer scrutiny, most of the signatories later denied having that view, and those that did were not biologists, with very few exceptions.  Nonetheless, this list and others like it have have been circulated as evidence against evolution.

In a counter move, the National Center for Science Education (NCSE) produced its own list of scientists who do support evolution.  However, their list was made of entirely of people with the first name Steve (or a derivation thereof), which they estimate make up about 1% of scientists. Within a month, they had over 200 signatories.  

As of last month, NCSE had almost 1200 Steves on its list.  You can see the Steve-O-Meter on their website.  If you're a scientist named Steve and you'd like to be an NCSE Steve, you can contact the NCSE to be added to their list.

By the way, the NCSE has recently begun to also defend the teaching of  global warming in U. S. classrooms.  They say they don't plan to start a new Project Steve for it, but I hope they do come up with something as funny and catchy.

Tuesday, February 7, 2012

Silk microneedles

Anyone who’s ever had an injection would welcome the replacement of normal syringes with ‘microneedles’.  These micron-sized needles only penetrate the outer layer of the skin.  This means that they deliver their drug payload without contacting any nerve cells, ensuring that the process is entirely painless.  Fiorenzo Omenetto and his team from Tufts University have improved the delivery system by making their microneedles out of silk.

Silk has several advantages over metal and the other materials that have been tried in microneedles. Unlike metal, silk is biodegradable.  Because the silk protein can be molded into appropriate shapes at room temperature, drugs can be incorporated directly into the pre-formed silk matrix without loss of potency.  This allows the embedded drug to be released slowly as the silk biodegrades, rather than being injected all at once.

The researchers successfully tested their silk microneedles both in vitro (observing the diffusion of enzymes into a gel pad and delivering antibiotics to a tissue culture) and in vivo (using the microneedles on mice).  They were able to control the rate of drug delivery by manipulating the consistency of the silk matrix.

Of course, a slower release of drugs, while advantageous in many ways, would require a longer exposure to the apparatus.  Rather than one quick injection, a patient might have to place a microneedle patch on his arm for as long as 30 minutes.  On the other hand, perhaps people could apply the microneedles themselves at home.

Monday, February 6, 2012

How your drug got its name

If you take any kind of medication, either prescription or over-the-counter, chances are your drug has at least three different names.  It will have a brand name, a generic name and a chemical name. If water were a drug, its three names might be 'Refresh', 'water' (some names are grandfathered in), and 'dihydrogen monoxide'. The latter two names must follow strict naming conventions.

Taking them in reverse order, the chemical name is decided on by the International Union of Pure & Applied Chemistry (IUPAC).  This name specifies the chemical nature of the active ingredient—that is, the composition of the actual molecule.  Unless you were a chemist, and probably not even then, you would have no idea what a drug did based on this name.  For example, can you guess what you’d take (RS)-2-(4-(2methylpropyl)phenyl)propanoic acid for? If you said fever and aches, you’d be right, because it’s the IUPAC name of ibuprofin (Motrin or Advil).

The generic name of a drug, which must be approved by the United States Adopted Name (USAN) Council, is chosen not just for its physical structure, but also for its physiological function.  The USAN keeps a list of word stems that can be strung together to create each new drug name. If you consulted this list, you might be able to figure out what the drug would be used for.  You could see that pantoprazole contains the suffix ‘prazole’ which indicates that it’s an anti-ulcer agent.  And in fact, pantoprazole is the generic name of a drug used to treat gastroesophageal reflux disease.

Finally, the brand name is selected by the pharmaceutical company that invented the drug.  This choice is often a matter of market research.  

Sunday, February 5, 2012

To do well in school, sign a contract

Most people are familiar with traditional classes in which the teacher chooses and grades assignments.  However, there is another grading system known as ‘contract grading’, that, though rarely used, seems to have a number of benefits.  Dana Lindermann and Colin Harbke of Western Illinois University found that contract grading significantly outperformed traditional grading among a small group of college freshmen.

There are a few key components to a contract grading system, most notably that the student decides which grade he or she is aiming for and signs a contract to that effect.  After that, the student can usually choose from a number of assignments, each of which is graded pass or fail at the discretion of the instructor.  Students are sometimes allowed to resubmit assignments or exams.  The number of satisfactorily completed assignments determines the final grade.

Forty first-year university students were randomly divided into two groups.  Each group of twenty took the same introductory psychology class with the same instructor and the same exams and assignments.  One group (traditional) received points for each assignment and a final grade based on the total number of points received.  Members of the second group (contract) were asked to sign a contract specifying which grade they planned to achieve and what that would require.  For example, to get an A, a student would need to get at least 80% on four exams, and complete three writing and three activity assignments.  B’s, C’s and D’s required fewer assignments. Interestingly, one of the contract choices specified what to do ‘if you want to earn an F’. I wonder how many students chose that option.

The amount of work and mastery required to get an A was equivalent in both groups. Nevertheless three times as many students in the contract group received an A.  The contract students also graded their instructor, the course and themselves more highly than the traditional students.  Remember, all students had the same instructor and assignments. 

The authors suggest that the difference was largely due to the fact that the contract students felt more in control of their own learning.  However, they don’t discount the possibility that the traditional group, in noticing that some of their peers were allowed to choose and resubmit assignments, simply became demoralized.

Saturday, February 4, 2012

For better child health, exercise safely

Many parts of the world are experiencing an epidemic in childhood obesity and its concomitant ill health.  One obvious way to alleviate this problem is to encourage children to get more exercise.  Unfortunately, according to researchers from Johns Hopkins and the Centers for Disease Control and Prevention, programs that encourage fitness generally do not give enough advice on avoiding injury.

Personally, I'm not so sure this kind of advice is necessary. Yes, pedestrian injury is the second leading cause of death in the U.S. for kids ages 5 to 14.  Injury in general is the leading cause of death for those under 44 years old.  This study does outline measures that can be taken to decrease injuries both prior to and during exercise.  For example, cities can design safe walking and biking zones and put fences around public pools.  They can also provide play equipment with proper surfacing and guard rails.

On the other hand, the study also discusses ways that participants can work to keep themselves safe.  Do we really need a study telling us that people engaged in water sports should learn to swim?