Science-- there's something for everyone

Wednesday, November 30, 2011

Just for fun: Surgical robots

I know someone who had his prostate removed via the Da Vinci surgical robot.  I wonder if he would have felt better or worse watching Ramesh Thurairaja of Southmead Hospital use the Da Vinci to peel a grape?  

Hat tip:  Not Exactly Rocket Science.

Tuesday, November 29, 2011

False confessions lead to false evidence

A surprising number of people unfairly accused of crimes will falsely confess to those crimes. The innocent people may be coerced into confessing, or they may simply be confused.  As I reported earlier, they may even confess just to get out of the interrogation room.  Unfortunately, for them, false confessions are often corroborated with otherwise poor or even fallacious evidence.

According to Saul Kassin from John Jay College of Criminal Justice, Daniel Bogart of the University of California, Irvine, and Jacqueline Kerner of Nova Southeastern University, possessing a confession can lead to a perfect storm of invalid evidence collection.  Upon obtaining a confession, law enforcement officers begin amassing evidence that corroborates that confession and discarding disconfirming evidence. 

This is not to say that officers of the law are deliberately trying to convict innocent people.  It’s just that once they have a confession, they naturally place more credence on eyewitness accounts that place their suspect at the scene of the crime and less on evidence that contradicts the confession.  In other words, the gathering of corroborating evidence may be corrupted by the very existence of the confession.

What can be done to ensure that the guilty are punished and the innocent go free?  It’s clear that confessions and eyewitness accounts should be considered of secondary importance compared to forensic evidence (fingerprints, DNA, etc).  But even more importantly, the people collecting that forensic evidence can't know who has or hasn't confessed.  Each piece of evidence must be evaluated independently in order to eliminate preconceived biases.

Monday, November 28, 2011

Doorway of forgetfulness

When I was in graduate school, my lab was divided between two rooms, each of which contained much used equipment and supplies.  We referred to the passage between those rooms as the ‘Arch of Forgetfulness’.  It was a common occurrence to find someone hesitating near an entrance with a puzzled look on her face.  Apparently, this phenomenon is not restricted to graduate students.  According to research by Gabrie Radvansky and her colleagues from the University of Notre Dame, forgetting why you entered a room is a universal experience.

The scientists conducted a series of experiments in which people progressed through either virtual or real rooms picking up objects (such as a white cone, or a blue cube) from one table and placing them on another table.  Sometimes the tables were within the same room, but at other times the participants had to pass through a doorway before depositing their items.  In all cases, the objects were hidden after being picked up (becoming invisible if virtual, or being concealed within a box if real).  Along the way, the participants were asked to remember what they were carrying.  In both the real and the virtual worlds, people did a better job remembering their objects if they hadn’t just crossed a doorway.

Returning to the starting position did not improve people’s memories either.  This last result surprised me a bit, as I seem to recall that reentering the first room did jog my memory.  Of course, upon returning to my lab bench I would have been faced with the same lack of ingredients that had set me on my journey to the other room in the first place.  That’s quite different from trying to remember if I had last picked up a red wedge or an orange cylinder. 

Sunday, November 27, 2011

Something to look forward to

That beautiful orthodontic-created smile may not last a lifetime.  According to research done at Malmö University, Sweden, our jaws shrink as we age, resulting in the very crowding we fought against in our youth. 

The researchers had taken plaster molds of the jaws of their dental students back in 1949.  Molds were taken of these same people in 1959 and in 1989.  As time progressed, people had less room in their jaws.  The difference was not great, no more than a millimeter in most cases.  However, even that small difference can lead to overcrowding, particularly among the lower teeth.

Despite this new data, I wouldn’t put down a deposit at your local orthodontist’s office for thirty years from now.  For one thing, this was a very small study.  By the forty-year mark, only 18 of the original students were still available.  For another, assuming you had straight teeth in your youth, the crowding in your dotage probably won’t be severe enough to warrant correction. Besides, as I've written before, there are more severe changes to the jawline that come with aging.

Instead, the dental researchers suggest that orthodontists keep in mind the eventual shrinking of their patients’ jaws when they prescribe treatment plans.

Saturday, November 26, 2011

Birds don’t like noise

The amount of noise in an area affects the number of songbirds seen in that territory.  Two studies from two different parts of the world show the same thing: birds don’t like noiseAlthough some species can be tolerant of noise, increased background noise levels lead to decreased diversity.

The first study took place in Puebla-Cholula, Mexico, and was run by scientists from the University of the Americas and from the Basque Institute for Agricultural Research and Development. The second study, conducted by researchers from the University of Extremadura, Spain, took place in the Iberian Peninsula.  In both cases, the number of bird species in an area was adversely affected by the amount of background noise.  In fact, noise levels were a greater predictor of species diversity than was size of test area, or human usage.  For example, university campuses had many more species of songbird than urban parks.

The Spanish study suggested that the cut off for discouraging the more sensitive bird species was 50 decibels (dB).  That’s about as loud as a normal conversation in a quiet location.  A whisper is at about 30 dB and traffic sounds heard from inside your car are around 85 dB.  All the regions studied had at least 38 dB of background noise, and some had over 70 dB.

What can be done to encourage birds to live alongside people?  The authors of both studies propose that urban planners include acoustic barriers, such as wooded spaces, within city limits.  

Friday, November 25, 2011

World’s lightest engineered material

Researchers from Caltech, from the University of California, Irvine, and from HRL Laboratories have developed the lightest material in the world.  Their new metal weighs less than 0.9 milligrams per cubic centimeter.  The previous lightweight champion, weighing in at about 1.9 milligrams per cubic centimeter, was a substance called ‘aerogel’. 

Just to put things in perspective, a typical bowling ball weighs somewhere between three and seven thousand grams.  If it were made of aerogel, the same bowling ball would only weigh about ten grams, and if made of the new metal, it would weigh less than 5 grams.  This is because both materials consist almost entirely of air trapped within a framework.  Aerogel is 99.8% air and 0.2% silicon dioxide, whereas the new ultralight metal is 99.9% air within a latticework of metallic microtubes.

metal on dandelion

Left:  Aerogel.

Right:  New metal resting on a dandelion without damaging it.
Credit: Dan Little, HRL Laboratories LLC.

Thursday, November 24, 2011

Just for fun: How not to cook a turkey

Okay, maybe more of a public service announcement than something for fun.  If you're considering deep frying your turkey this year, you may want to rethink that choice.

Hat tip:  Greg Laden's Blog.

Wednesday, November 23, 2011

Practicing on toys

Surgical skills laboratory with toy animalsIt’s not only small children who get practice dealing with pets and other people through the handling of toys.  According to a study led by Rikke Langebæk of the University of Copenhagen, veterinary students can also benefit from doctoring toy animals before they start operating on the real thing. 

Veterinary students will one day be called upon to perform surgical procedures on people’s beloved pets and valuable lifestock.  In preparation, they often practice on laboratory animals.  However, this has several drawbacks.  For one thing, the future vets understandably feel distress at causing these animals any unnecessary suffering.  For another, the pressure of having to operate on living animals can make students anxious, never the best learning environment.  And of course, there’s the cost of maintaining and caring for laboratory animals.

In order to alleviate these problems, Langebæk developed a skills laboratory in 2007 that uses toy animals instead of living animals.  These are not your ordinary stuffed toys from Hallmark though.  The toys contain organs and veins that simulate those found in real animals. 

Thus far, students say the toys are a good model for learning surgical procedures, and that operating on the toys gives them confidence for moving on to the real thing.

Tuesday, November 22, 2011

Disgust by any other name is still disgust

One controversy in cognitive research is whether language is critical for the perception of emotion.  In other words, can you feel something just as strongly if you can’t label that feeling?  According to scientists from the Max Planck Institute, the answer is yes.

The researchers compared German speakers to speakers of Yucatec Maya, a language spoken in the Yucatan Peninsula that has no separate word for ‘disgust’.  When shown photographs of people displaying various emotions, Yucatec Maya speakers could not distinguish verbally between ‘disgust’ and ‘anger’.  Does this mean that the Mayans do not perceive any difference between these two emotional states?

To answer this next question, the Germans and Mayans were shown a new set of photos.  First, they were shown a person displaying a digitally fine-tuned mix of emotions, such as 80% angry, 20% disgusted.  They were next presented with a pair of photos, the original and a picture of the same person but with a different mix of the same two emotions.  In some cases, the dominant emotion was the same in both pictures, but in other pairs of pictures it was reversed (one picture mostly angry but a little disgusted, the other mostly disgusted but a little angry).  The subjects were asked which of the two pictures was identical to the single picture they had just seen. 

This task is easier for most people when the dominant emotions in the non-identical picture are reversed. But is that due to the verbal labels people place on those emotions (I’m looking for a picture of a disgusted person, and the person on the left is more angry than disgusted)? In that case, having labeled the angry and the disgusted person the same way, the Mayans should do more poorly in the matching game. 

As I’m sure you’ve guessed, the Yucatec Maya speakers performed the task just as well as the German speakers.  Mayans may not have a word for ‘disgust’, but they know it when they see it.

Monday, November 21, 2011

Physical leanings can affect intellectual leanings

On a standard number line, numbers increase as you progress from left to right.  People therefore tend to associate smaller numbers with the left hand side and larger ones with the right.  Researchers from Erasmus University Rotterdam, led by Anita Eerland, wondered whether leaning one way or another could affect people’s estimations of amounts.  You won’t be surprised to learn that it could.

The psychologists placed 33 undergraduate volunteers on Wii Balance Boards that were falsely set to indicate that the subjects were standing upright even when they were really leaning to the left or right.  While balanced, the participants were asked to estimate a series of quantities, such as the height of the Eiffel Tower.  Subjects who were leaning to the left consistently gave smaller estimates than those either standing upright or leaning to the right.

I’ve written before about how people tend to look leftward when thinking of small numbers and rightward when thinking of larger ones (there’s that number line again).  In this case, unconsciously leaning to one side or another may influence one’s thoughts about numbers and amounts.

Sunday, November 20, 2011

Hard-wired for duets

Plain-tailed wrens (Pheugopedius euophrys) routinely sing in duets.  This isn’t so unusual for birds conducting mating displays.  What is unusual is that the birds seem hardwired to cooperate with one another.  Not only is the combined song almost indistinguishable from a single voice, but the birds strongly prefer the duets to any other sounds, including their own individual songs.

Eric Fortune from Johns Hopkins University led a team of researchers to the cloud forests of Ecuador to study the songs of plain-tailed wrens.  The birds sing in male-female pairs, with the two partners alternating notes so tightly that they sound like a single bird.  When captive wrens were subjected to brain scans, the scientists discovered that each bird’s neurons fired more strongly when exposed to the duet than to that bird’s own part of the song. 

Because all vertebrate brains are similar at some level, the scientists believe this finding will have implications for the evolution of cooperation.  As Fortune states:

Brains among vertebrate animals—frogs, cats, fish, bears, and even humans—are more similar than most people realize. Thus, the kinds of phenomena that we have described in these wrens are very relevant to the brains of most, if not all, vertebrate species, including us humans.

You can watch Fortune’s explanation below:

For more clips showing each bird’s part in the duets, click here

Saturday, November 19, 2011

Just for fun: Micrograph Contest

Every year, Electron, Ion and Photon  Beam Technology and Nanofabrication (EIPBN) hosts a micrograph contest.  This year, 86 entries were submitted.  You can see all six prize winners and 10 honorable mentions here.  

Here are a couple of examples:

The grand prize winner, submitted by Joel Yang and entitled 'Reading Tea Leaves':

Description: SEM image of M.C. Escher's 1948 Drop as "sketched" by e-beam lithography in such a way as to preserve the grayscale information. 

Medium: HSQ on Si

Magnification (3"x4" image):3,300x

And an honorable mention by 
H.D.Wanzenboeck and G.Hochleitner of the University of Technology Vienna, entitled 'The Engineer's Pole Dance (a little help please)':

Description: Carbon nano-fibers on FEBID iron catalyst particle
Magnification (3"x4" image):  50000

Friday, November 18, 2011

Bad news for people needing knee replacement

People who need to have a knee replaced have almost certainly been enduring a considerable amount of pain for some time prior to their surgery.  Unfortunately, if they’ve become dependent on narcotic pain relievers (opioids), their prognosis after the surgery will be worse.  So says a new study led by Michael Mont at Sinai Hospital of Baltimore.

The researchers compared 49 patients who had been using opioids for pain management with a group of matched controls who had not used narcotics. In all categories (length of hospital stay, number of complications, amount of post-operative pain), the opioid users did worse.  They even had poorer recovery of motion and function in the replaced knee.

It’s not clear why regularly taking narcotics prior to knee replacement has this effect.  One possibility is that subjects who resort to opioids have lower pain thresholds to begin with.  As a group, they may also be less compliant with recommended rehabilitation and physical therapy.

What can be done to help people who need knee replacement?  The authors suggest that patients be weaned off strong opioids prior to the surgery.  That sounds a lot easier said than done, especially if these are the very people who feel pain more intensely.  If these patients could have been made comfortable with milder pain medications they probably wouldn’t have been using narcotics in the first place.

Although this sounds like a no-win situation for people with bad knee pain, it’s still good to be aware of it.  Perhaps this knowledge can motivate patients to work hard at reducing their pain medication levels prior to surgery in order to improve their outcomes.

Thursday, November 17, 2011

Brains and guts were not in competition

Humans have large brains and small digestive tracts, relatively speaking.  One theory holds that these two energetically expensive organs are inversely related.  That is, in order for brain size to increase, gut size must decrease.  However, Ana Navarrete, Carel van Schaik and Karin Isler from the University of Zurich have found that this is not the case

The researchers compared the organ sizes of 100 different mammalian species, including 23 primates.  The amount of adipose tissue (body fat) was calculated separately.  When fat-free body mass alone was considered, there was no correlation, inverse or otherwise, between brain size and digestive tract size.  In fact, there was no correlation between brain size and any other organ sizes either.  Interestingly, there was a correlation between fat storage and brain size.  Animals with larger amounts of adipose tissue had smaller brains.

The authors postulate that storing fat and accumulating brain power are two methods of combating starvation.  Bears evolved to take advantage of one strategy, and humans the other.  

More information at Not Exactly Rocket Science.

Wednesday, November 16, 2011

Mars500 crew is safely home

Okay, they didn’t actually go anywhere.  The crew of six men, including three Russians, one Chinese and two Europeans, have spent the past 520 days enclosed in a research facility at the Moscow Institute of Biomedical Problems in Moscow.  The purpose of the project, dubbed Mars500, was to see what effect the prolonged periods of isolation required to undergo a journey to Mars would have on astronauts.  The six volunteers emerged with smiles and assurances that they were ready for the real thing.

Once sealed inside the facility, the crew’s only contact with the outside world was through communications with ‘mission control’, which were artificially delayed to simulate transmission over great distances.  The 17 months ‘away’ included long stretches of confinement to the spacecraft interrupted by one brief interval when the crew were able to don spacesuits and simulate a stroll around the Martian surface.

During their confinement, the crew conducted over a hundred experiments, including many on their motivation and psychological wellbeing. The results thus far look promising for individuals attempting an actual journey to Mars.

You can view mission diary entries here.  Below are a couple of examples:

The first 'Marswalk' by Diego Urbina and Alexandr Smoleevskiy on February 14, which lasted one hour and 12 minutes (but don't worry, the video is less than four minutes long).

And a typical housecleaning day.  I wish my house was that clean!

Tuesday, November 15, 2011

Cancer killing peptides

Researchers from USC and various Korean universities have identified two virus-derived peptides that can kill cancer cells.  The small viral proteins do this by mediating levels of the tumor suppressor protein known as p53.  To understand what’s going on, let’s meet the proteins involved.

When a protein with an apparent mass of 53 kilodaltons was first discovered in 1979, it had an unknown function.  The name p53 has stuck ever since, despite the fact that we now know it’s a tumor suppressor.  Among its functions is the initiation of apoptosis, or programmed cell death. It can also halt cell cycles during DNA repair to give the repair enzymes more time to correct errors.

Normally, p53 levels are low.  After all, the unnecessary slowing down or killing of cells would be wasteful.  There are various feedback mechanisms for controlling the levels of p53, including the action of a protein known as HAUSP.  The two peptides in this study, which were derived from Kaposi's sarcoma–associated herpesvirus, selectively bind to and inactivate HAUSP.  Without that protein, p53 levels are free to rise. More p53 means more cell death, which is a good thing when the cells in question are cancerous.

Needless to say, it's a long road between these experiments and any clinical applications.  Which is not to say that a practical usage won’t one day be found for these small peptides.

Position of the p53 gene on chromosome 17.

Monday, November 14, 2011

Why we don’t inherit paternal mitochondria

In addition to their DNA complement, sperm and egg cells (oocytes) also contain cellular components such as mitochondria.  However, sperm do not contribute any mitochondria to the resultant offspring, despite being entirely engulfed by the ooctye during fertilization.  In fact, genealogies can be traced through the female line using mitochondrial DNA.  What happens to the paternal mitochondria? According to researchers from several French institutions, right after fertilization the oocyte quickly digests all the paternal organelles, including the mitochondria.

Although eggs and sperm contribute equal amounts of DNA to the zygote, the egg contributes the bulk of the cellular material within that zygote.  This is not surprising, considering that a human oocyte contains about 85,000 times as much volume as its partner, the human sperm.  It’s not just a matter of dilution though.  The male organelles are actively digested by the oocyte. This was confirmed by the disappearance of all paternal mitochondrial DNA in the zygote.  When the sperm-digesting (spermophagy) machinery was artificially disrupted, the resulting offspring retained both maternal and paternal mitochondria.

Although these experiments were conducted in tiny worms called nematodes, the scientists saw evidence of the same processes in mice, indicating that the disintegration of paternal organelles may be universal. The authors speculate that this mechanism evolved to spare zygotes from mitochondria derived from cells with a very high metabolic rate (sperm) and consequently a higher than usual mutation rate.  In any case, by shutting down the spermophagy machinery, scientists can now create offspring with both maternal and paternal mitochondria.  That should yield some interesting results.

Sunday, November 13, 2011

Voting at the Mall

Robert Stein from Rice University and Greg Vonnahme from the University of Alabama propose that cities open up voting centers in addition to regular polling places.  These centers would be in retail areas with easy access and large parking lots. 

According to a U.S. census, 64% of adult citizens cast a vote in 2008 election.  Although this is admittedly higher than I feared, it could still stand some improvement. Attempts to raise voting levels have included implementing what are termed ‘non-precinct voting.’  This is any voting that occurs outside of the neighborhood or precinct in which the voter lives.  The most common examples of non-precinct voting are early voting or vote-by-mail.

Stein and Vonnahme propose adding voting centers to the list of ways a person can vote. These centrally located voting centers would ideally be convenient places to visit while going about one’s daily business. After all, the number one reason cited for not voting was ‘too busy, conflicting schedule’.  If people could vote near their place of work, it might make things just that much easier. 

You can watch a description below.

Saturday, November 12, 2011

Just for fun: Minute Physics

I recently stumbled across the entertaining and informative video clips produced by Minute Physics.  They explain such concepts as gravity, the uncertainty principle, quantum tunneling and a myriad other topics.

Here's a sample clip that explains dark matter:

Friday, November 11, 2011

Sticking with natural inspiration

Scientists often turn to nature for inspiration.  A case in point comes from researchers from the University of Kiel, Germany, who developed a novel adhesive based on an insect model.  Their new type of tape was presented at the AVS 58th International Symposium & Exhibition.

Many insects use thousands of tiny hairs on their feet to climb up walls.  These minute hairs are able to make tight contact with almost any type of surface, even under water, and stick to that surface.  The University of Kiel researchers created their own version of hairy feet, namely a silicone tape covered with tiny hairs.  Like the original, their tape works when wet, leaves no sticky residue, and is completely reusable.  It’s also strong enough to suspend a scientist from the ceiling.

Caption: Achim Oesert, a member of the Functional Morphology and Biomechanics group at the University of Kiel, Germany hangs from the ceiling using bioinspired polymer tape while surrounded by other team members.

Credit: University of Kiel, Germany.
By the way, after some digging I discovered that ‘AVS’ once stood for ‘American Vacuum Society’, though they don't use that name anymore.  Perhaps the AVS, as a member of the American Institute of Physics and a supporter of basic science research, no longer wishes to be associated with floor cleaning products in the public mind.

Thursday, November 10, 2011

Microbial gene transfer

If we multicellular organisms want to transfer genes around, we have to reproduce.  Not so for bacteria, which are able to receive and donate genes to one another via horizontal gene transfer (HGT).  Just how common is this practice among the microbes? Eric Alm led a team of scientists from MIT in determining the frequency and specificity of these transfers.

HGT occurs when one bacterium transfers one or more genes to another completely unrelated bacterium, often by injecting the DNA straight through the recipient’s cell wall.  The two microorganisms don’t even have to be of the same species, proximity is the main limiting factor.  In fact, the researchers found over 10,000 cases of transfer between 2,235 different bacterial genomes.

Having the donor and recipient occupy the same ecological niche appears to be key for successful gene transfer.  For example, HGT was most common in bacteria with the same oxygen tolerance, or for those living in the same part of the body.

Why is HGT important?  Fully sixty percent of the transfer events involving human-associated bacteria included an antibiotic resistance gene.  Forty-two of these genes were found in the bacteria of both people and livestock, and on forty-three occasions antibiotic resistance genes had moved across national borders.  Clearly, we need to rethink our agricultural practices, especially the adding of prophylactic antibiotics to animal feed, a convention that is already banned in many European countries. 

Wednesday, November 9, 2011

Don’t treat a fever

We seem to have a temperature theme going here. Yesterday cooling, today, heating for better health.  A slightly higher body temperature not only makes it more difficult for microbes to replicate, but also enhances key components of our immune systems.  Researchers from the Roswell Park Cancer Institute found that raising the core body temperature of mice by two degrees Celsius before exposing them to an antigen preferentially increased the number of CD8+ immune cells that could respond to that antigen.

CD8+ cells (also known as cytotoxic or killer T cells) are a type of lymphocyte or white blood cell whose job it is to kill infected cells.  Briefly, a cell that has been infected by a virus or bacteria will present bits of that microbe on its surface. Those antigens then interact with receptors on the membranes of T cells such as CD8+ cells.  This interaction results in both proliferation and activation of the immune cells, which then release cytotoxic (cell-killing) compounds. Increasing the body temperature of mice led to an increase in the number of activated CD8+ cells, possibly due to tiny changes in the lymphocytes’ cell membranes.

It’s not surprising that a slight fever can be beneficial to an animal suffering from an infection.  Many animals will deliberately raise their temperatures when ill.  Now we know why, namely that a higher body temperature can have a direct and positive effect on the immune system.  That said, the authors caution that very high fevers should still be treated.

Tuesday, November 8, 2011

Therapeutic hypothermia for a heart attack

Yesterday, I wrote about warming, now a story about cooling.  Patients who underwent therapeutic cooling following a heart attack fared better than controls, according to a study by doctors at the Mayo Clinic.  Over two and half times as many hypothermia-treated patients survived their cardiac arrest as patients who had not been drastically cooled.

Therapeutic cooling is the process of lowering the body temperature to a point where metabolism is slowed down.  This can be done by applying cold packs externally or by IV fluids. The target body temperature of this process is 32–34 °C (90–93 °F).   The hope is that such treatment can prevent the brain damage that often results from lack of blood flow following cardiac arrest.  However, doctors were concerned that the extreme cooling could delay post-heart attack awakening, a critical component of continued diagnosis and treatment.  This did not turn out to be a problem.  Of the 227 patients in the study (128 treated with hypothermia and 99 controls), all awakened within the same time frame, and the cooled patients had a significantly higher survival rate.

Sudden cardiac arrest is the leading cause of death in U.S.  With current treatments, only 7% of victims survive.  Perhaps if patients can be immediately cooled down, that percentage might go up.

Monday, November 7, 2011

Global warming is real

In case you needed any more evidence, here are two more studies showing exactly that.  The first study, the Berkelely Earth Surface Temperature Study, is a review of the data from 15 sources compiled from almost 40,000 different surface temperature stations around the Earth.  This study, run by Berkeley physicist and former global warming skeptic Richard Muller, confirms that the Earth is getting warmer.  Muller himself was surprised at how closely the new data matched that of the previous studies.

Comparison of data showing decadal land-surface average world temperature changes from 15 different sources, some going back as far as 1800.

In case you aren’t familiar with the acronyms:
NASA GISS—NASA Goddard institute for Space Studies
NOAA—National Oceanic and Atmospheric Administration
HadCRU—Hadley center Climate Research Unit (the group that had been accused of scientific malfeasance by global warming deniers, but was later cleared of all wrongdoing).

Credit: Image courtesy of Berkeley Earth Surface Temperature.

The Berkeley study only went back a couple of centuries.  The next study, by Svante Björck of Lund University, goes back 20,000 years.  By examining ice cores from both the Northern and Southern hemispheres, he was able to show that the warming going on today is unlike previous warming events in Earth’s history.  On previous occasions, only one hemisphere warmed at a time, not both as is happening now.  This is evidence that the climate change we see is caused by an external force, namely us.

Sunday, November 6, 2011

Getting Grandpa’s kidney

As of last year, 93,000 people in the United States were on the waiting list for a donor kidney.  Needless to say, there aren’t enough to go around.  Now, new research by a team from Johns Hopkins may have broadened the search criteria.  The doctors, led by Dorry Segev, have found that older donors can safely donate kidneys even past the age of 70.

The researchers compared 219 kidney donors who were over the age of 70 at the time of their donation to a matched set of seniors who had not donated organs.  Not only did mortality not increase for the donors, but it actually decreased over the ten years after the donation.  This is not to suggest that donating a kidney can prolong your life.  Despite matching controls to donors as carefully as possible, the authors suggest that the criteria to become an older donor may have selected for slightly healthier individuals.  In other words, the donor group would probably have lived longer regardless of whether or not they gave a kidney.  In any case, they certainly weren’t handicapped by their choice to donate a kidney.

How did the recipients fare?  The kidneys from donors over age 70 did not last as long as kidneys from live donors under age 60.  However, the older kidneys were just as good as younger kidneys from deceased donors.  

In conclusion, if you need a kidney and Grandpa is willing to give you one of his, you should take it.  It’s a win-win for everyone.

Saturday, November 5, 2011

Just for Fun: Name the array

The National Radio Astronomy Observatory (NRAO) has been upgrading its Very Large Array (27 radio antennas outside of Socorro, New Mexico) with new electronics to replace the previously installed 70's era equipment.  To commemorate this change, the designation-challenged astronomers at NRAO are inviting the public to suggest a new name to match the array's new capabilities.

If you have a name in mind, especially one that's more imaginative than 'Hey, That's a Lot of Telescopes!' you can submit it here.  But don't delay! Entries will only be accepted until midnight on December 1st.   

Very Large Array, Socorro, New Mexico, taken by Hajor, 8/8/2004.

Hat tip:  Skeptics' Guide to the Universe.

Friday, November 4, 2011

Do bacteria age?

Bacteria reproduce by simple fission, that is, they divide into two.  Until recently, those two daughter cells were thought to be identical.  However, a new study by University of California, San Diego researchers Camilla Rang, Annie Peng and Lin Chao calls that assumption into question.  According to their research, not only are the daughter cells not identical, but the differences between them allow bacteria to stay perpetually young.

False color image of E. coli.

Aging in multicellular organisms usually involves irreparable cell damage.  As our individual cells accumulate damage, this deterioration is eventually felt in our organs and entire bodies.  Single celled organisms also become corrupted over time.  It had been thought that an injured cell would distribute that damage evenly between its two daughters.  That turns out not to be the case.  Instead, each dividing cell preferentially gives one daughter most of the damage.  As this cycle goes on, a subset of the bacterial cells remain forever youthful and undamaged.

So the answer to whether bacteria age appears to be both yes and no.  Within a bacterial colony there are groups of cells that accumulate more and more damage, the very definition of aging.  But there are also cells that are constantly rejuvenated.

Thursday, November 3, 2011

More scarless surgery

I’ve written before about surgeons using natural orifices (usually the mouth or vagina) to perform surgical procedures on internal organs. Now Kofi Boahene and his colleagues from Johns Hopkins have used a scarless technique to access and remove tumors at the base of patients’ skulls.

Traditionally, expunging such tumors involves making incisions in the face and often removing bone.  Aside from the trauma of having disfiguring scars, the procedure can result in nerve damage and requires long recovery times.  Instead, the Johns Hopkins doctors used a different route to get to the tumor.  They used what Boahene describes as a ‘window…above the jawbone and below the cheekbone’.

After feeling around in my mouth for a bit, I can’t say that I can locate such a window.  I’ve therefore included the illustration below, which shows a ready-made access point behind the lower teeth.  By going through this window inside the mouth, the doctors decreased the surgical time required to remove a tumor by two thirds, and the recovery time to only one day.  And of course, there are no visible scars.

Illustration by Patrick J. Lynch, 12/23/2006.

This kind of surgery won’t work for everyone, but it may be an excellent choice for many patients who have tumors at the back of their heads or necks.

Wednesday, November 2, 2011

Junk DNA separates human from chimp

Researchers from the Georgia Institute of Technology have found that large DNA insertions near but not within genes may account for the evolutionary differences between humans and chimpanzees.   This may answer the question of how the two species can be so dissimilar, despite having genes that are over 98% identical. 

While it is true that the coding regions (parts of the genome that code for amino acids) of chimps and humans are virtually identical, the regions around those genes are much less similar. You may know these locations outside genes as 'junk DNA'.  However, not all junk is created equal, and some of these sequences do have a function.  

For example, self-replicating genetic fragments called transposable elements have inserted themselves into the non-coding regions of both humans and chimps, sometimes in tens of thousands of copies. Although these insertions don’t alter the genes themselves, they can affect gene expression.  In other words, they can affect how many copies of a protein are made from a particular gene.  To give a couple of overly simplified examples, suppose that one protein is involved in intelligence, and another in production of body hair.  Chimps and people may have identical genes encoding those proteins, but they don’t make the same amounts of them.

As expected, the scientists found that variation between chimps and humans caused by large insertions in non-coding regions did affect gene expression.  This means, of course, that regulatory sequences may be as important as genes in driving evolution.

Illustration by Kayla Orlinsky, 10/27/2011.