Science-- there's something for everyone

Monday, February 28, 2011

Double whammy from early balding

Male pattern baldness, or androgenic alopecia, affects about 50% of all men. A subset of these men began to lose their hair as early as twenty years old. To add injury to insult, those same men who went bald early are the most likely to later develop prostate cancer.

Baldness and prostate cancer were both known to be linked to male hormones called androgens, implying a possible connection. To find that association, Philippe Giraud led a team of French oncologists in comparing prostate cancer rates in differently-haired men. Out of a pool of 669 subjects who were asked about their hair loss, 388 had a history of prostate cancer. Those men who had begun to lose their hair at age 20 were twice as likely to have prostate cancer as those who lost their hair later in life, or who did not have androgenic alopecia.

The researchers noted that the time of detection and the progression of the cancer did not differ between the early and late hair losers. In other words, beginning to go bald at age 20 was a strong indicator that a person would someday get prostate cancer, but did not indicate when the cancer would develop or how aggressive the tumor would be. It does suggest that early balders should begin prostate cancer screening at an earlier age.

Sunday, February 27, 2011

Remote explosion of land mines

Land mines are a devastating problem in some parts of the world, including Columbia, from which Félix Vega and Nicolas Mora, doctoral students at Ecole Polytechnique Fédérale de Lausanne, originate. The two young scientists made finding a way to remote detonate those mines the subject of their thesis projects.

The solution they came up with was to send out electromagnetic pulses that would trigger the mines’ detonators. Although simple in concept, it took two years to find a way to send a pulse that was powerful enough to reach the detonators, which could be buried deep underground. Eventually, they found the right frequency range and were able to detonate mines (provided by bomb disposal experts) at a distance of 20 meters.

The researchers still have some work ahead of them to improve the device. As Félix Vega says:

Now we have to develop a smaller prototype that is weather-resistant and especially easier to transport in the field. In Colombia, we often have to travel on small country roads.

If this method is successful in the field, it will be a tremendous help not only to the native people who are currently injured in great numbers by the mines, but also to the military personnel tasked to remove those mines.

Saturday, February 26, 2011

Some benefits to distractions while driving

Being distracted by cell phones is a well-known driving hazard. On the other hand, driver fatigue is responsible for tens of thousands of accidents each year. Paul Atchley and Mark Chan from the University of Kansas tested whether adding a bit of verbal distraction to a drive could yield a net positive result. Their cautious answer is that it can.

The researchers put 45 volunteers in a driving simulator for 30 minutes. Their ‘route’ was a flat, monotonous stretch of highway. Along the way, each driver ‘passed’ billboards and other visual memory tests. Two groups were given the task of free associating one-word responses to randomly selected words, one group for the entire drive, and the second group only for the last part of the drive. A third group drove without being given any additional verbal task. Each group was presented with occasional road hazards to avoid. At the end of the 30 minutes, the participants were asked to recall as many billboards as they could. They were also evaluated for their ability to stay in their lanes and for how much they had to correct direction with the steering wheel.

The drivers who were distracted by the verbal task performed slightly better than those who were not playing word association. The difference was the greatest during the last five minutes of the drive when everyone was the most bored by the route.

I should caution that the differences were not great, and that this was a small study. In contrast, there are many studies showing the dangers of talking on cell phones while driving and even worse while texting. However, this new data does suggest that drivers’ fatigue can be even more dangerous, and that adding a bit of distraction might actually help drivers to stay focused on the road.

Top: Photo by Ed Poor, 2/25/2007.

Friday, February 25, 2011

Just for fun: Evolution timeline

Youtuber thelunctable100 created this video for a science class.

Thursday, February 24, 2011

Three year olds choose to share

If you are the parent of young children, this finding may surprise you. When left to their own devices, three-year-olds who cooperated to acquire prizes willingly shared those prizes. So says a new study by Felix Warneken of Harvard University and his colleagues from the University of Göttingen and from the Max Planck Institute.

The researchers put a pile of treasures (gummy bears, stickers etc.) inside a transparent box that was placed on a wheeled board. The box, which contained either one or two child-hand sized windows, was placed out of reach. However, the board was attached to a rope that could be used to pull the box within reach. The catch was that the board was too heavy for a single child to pull. Only if two three-year-olds worked together could they pull the box close enough to reach the prizes through the windows. Once the bounty was within range, the children almost always divided the spoils more or less equally. This was true even if there was only one window and only one child could pull out all the goodies. There was virtually no conflict, and in fact, sometimes one child would insist that the other take his share.

This kind of sharing was thought to be possible only for children over six years old. Even the authors were surprised to find that three-year-olds could share so willingly. To be clear, the children only shared the prizes with those who had cooperated with them to get those items. This does not necessarily translate to be willing to share toys with peers who have no claim on them. Still, it's a nice result.

Wednesday, February 23, 2011

Getting fingerprints from fabrics

Fingerprint analysis has been a mainstay of criminal investigation for over a hundred years. However, it’s still very difficult to collect fingerprints from fabrics. That may be changing, thanks to the efforts of forensic scientists at the University of Abertay Dundee and the Scottish Police Services Authority (SPSA).

The team, led by David Bremner, successfully used a technique called vacuum metal deposition (VMD) to lift prints from some kinds of fabrics. This multistep process was effective on nylon and polyester, but revealed only finger impressions on cotton and cotton blends. First, the fabric is placed in a vacuum chamber. A thin layer of gold, which has been heated until evaporation, is sprayed over the fabric. Finally, zinc, which has been heated in the same manner, is sprayed over the gilded fabric. The zinc only attaches to the gold in places where there is no fingerprint, revealing any human contact with the fabric.

Thus far, the team has lifted a few identifiable fingerprints as well as hand shapes from various fabrics. Although they hope to improve the technique, they maintain that even this small amount of information could prove useful. As Paul Deacon of SPSA observes:

For example, an impression of a palm print on the back of someone's shirt might indicate they were pushed off a balcony, rather than jumping.

Perhaps more importantly, finding even a trace of a print could tell forensic scientists where to look for DNA evidence.

Tuesday, February 22, 2011

Paleontology by laser scan

The embedded track

Studying fossils used to have one major drawback: you had to have your hands on the actual fossil. Thomas Adams and his colleagues from Southern Methodist University found a solution that would allow paleontologists (and interested lay persons) around the world to study the same fossil. They proposed making high-resolution 3D scans of the objects and disseminating them for free.

The team used portable 3D laser scanners to digitally archive the footprint (shown above) of a large meat-eating dinosaur. The footprint, Eubrontes glenrosensis, was part of a deteriorating walkway in Dinosaur Valley State Park, Texas. Thanks to the efforts of Adams et al., the 3D digital model is now free for anyone to download. By the way, if you’re wondering why you’ve never heard of E. glenrosensis, it’s because that’s the name of the trackway, not the dinosaur that made the prints, which is believed to be Acrocanthosaurus tokenensis. Because it’s impossible to prove which dinosaur left a print, footprints are given their own unique names.

Much of the impetus for developing this methodology was to preserve specimens that are succumbing to the elements. Although there are 3D scans of some artifacts, there is no single standard format for creating them. The scientists hope the success of this proof of concept test will encourage other labs to accept the use of these portable scanners.

Thomas Adams explains:

Monday, February 21, 2011

Horizontal genetic transfer in fungi

Genes are normally transferred ‘vertically’ from parent to offspring. For the past few decades, biologists have become increasingly aware of the importance of ‘horizontal’ transfer in which individuals, almost exclusively microorganisms, acquire genes from their neighbors. Jason Slot and Antonis Rokas of Vanderbilt University document a case of horizontal transfer in fungi.

A 23 gene cluster responsible for the entire production pathway of sterigmatocystin, a toxin, was transferred from the fungus Aspergillus nidulans to the fungus Podospora anserine. In case you’re wondering how different two fungi could possibly be, these particular fungi occupy two different taxonomic classes. To put that in perspective, all mammals constitute a single class.

As of now, although plentiful in bacteria, only a few cases of horizontal transfer are known in multicellular organisms and the exact mechanism in these complex organisms is not yet known. However, the researchers speculate that this type of genetic shuffling may have played a larger roll in generating genetic diversity than previously thought. If that's true, biologists may have to rethink the traditional 'tree of life'.

You can see an explanation by Slot and Rokas below:

Top: photo of Aspergillus nidulans by Plasmidmap, 12/3/2007.

Sunday, February 20, 2011

Reduced pain through body imagery

Here’s a result I did not expect to see: simply looking at the injured part of your body can reduce pain levels. This counterintuitive finding was exposed by Flavia Mancini and her colleagues at University College London.

Eighteen brave volunteers were fitted with a heat probe on their left hands. The heat was gradually increased until it became painful, at which point the participants could press a foot petal to stop the experiment. Although the subjects were all told to look toward their left hands, what they saw was controlled by a series of mirrors. Some people saw their own left hand, actual sized, some saw a wooden object in that position, and some saw their hand distorted to look larger or smaller.

People who saw their own hand could tolerate about 3°C higher temperature than those who had seen a piece of wood. Even more intriguingly, those who saw a reduced sized hand experienced more pain than those who saw a normal sized hand. The lucky ones who saw an enlarged hand could tolerate the most heat.

This goes counter to all the advice I’ve heard over the years about looking away during painful examinations or treatments. Instead, if this small study is to be believed, the better tactic would be to watch intently as your injuries are tended. In fact, whenever possible, patients should be given mirrors to enlarge the damaged area.

Saturday, February 19, 2011

To improve concentration, take a break

I’ve written previously about how people don’t have a cognitive limit on how long they can concentrate. Now, Alejandro Lleras and Atsunori Ariga from the University of Illinois have found that occasional breaks from a task actually improve one’s concentration.

After prolonged periods, most people find their attention beginning to wane. Lleras and Ariga wondered if this was due to a phenomenon known as ‘habituation’. Over time, we cease to notice stimuli that were once very strong. For example, we may stop hearing trains going by or feeling our jewelry against our skin. This holds true for visual input as well, we may stop seeing things that are constantly present. Lleras and Ariga proposed that this phenomenon would hold true for thoughts as well.

As Lleras explains:

If sustained attention to a sensation makes that sensation vanish from our awareness, sustained attention to a thought should also lead to that thought's disappearance from our mind!

The researchers tested this hypothesis by dividing 84 volunteers into four groups. All were given a 50 minute long computerized task to perform. The first group got no diversions. The other three groups were given a set of four digits prior to the task. Groups two and three were told to respond if they saw any of those digits during the task, but only group two ever encountered the digits. Group four was told to ignore the digits.

Only group two did not show a decrease in concentration over the 50 minute period. This was the only group to switch its attention from the main task to attend to the side task (responding to the digits). Those two brief shifts in attention were enough to allow the participants to resume their main task with full concentration.

The scientists suggest that taking short mental breaks may help people to remain focused on their tasks. However, I should point out that the breaks need only be fleeting to achieve the desired effect. Going skiing for the weekend is not necessary.

Friday, February 18, 2011

Just for fun: Bad Project

Maybe it's because I'm a former graduate student myself that I found this video so amusing. The first time through, I didn't even notice that 'Lady Science' is wearing costumes made of lab materials like biohazard bags and bench diapers.

The Zheng Lab from Baylor College at their 2011 retreat:

Hat tip: Pharyngula.

Thursday, February 17, 2011

Earliest life in clay bubbles

Although the progression of evolution is well understood after life first appeared on Earth, the origin of that initial life is still largely speculative. Applied physicists from Harvard, Princeton and Brandeis have suggested a possible candidate for the earliest cells: clay bubbles.

Montmorillonite, first found in the similarly named region of France, is a naturally occurring clay that appears in tiny (one micron across) plates. This type of clay has been previously shown to be a chemical catalyst, assisting in the formation of both RNA and lipids.

According to the researchers, when suspended in water, montmorillonite clay will spontaneously form tiny capsules around any air bubbles it encounters. Because the clay is microscopically porous, that air bubble inside the clay sphere is soon replaced with water. The pores are just large enough to allow single nucleotides and other organic building blocks to enter. Once inside the shell, the montmorillonite catalyzes the formation of larger molecules that are now trapped inside. And voila! You have your first proto-cell.

According to first author Anand Bala Subramaniam,

Whether clay vesicles could have played a significant role in the origins of life is of course unknown, but the fact that they are so robust, along with the well-known catalytic properties of clay, suggests that they may have had some part to play.

Caption: Fatty-acid liposomes compartmentalize inside a clay vesicle.

Credit: Anand Bala Subramaniam, Harvard School of Engineering and Applied Sciences.

Wednesday, February 16, 2011

Biopsy by laser

Skin biopsies may be headed to the medical museum, thanks to work developed at Michigan State University and Harvard. The research team, led by Marcos Dantus and Sunney Xie, have developed a way to use lasers to replace biopsies altogether.

The scientists used a modified version of Raman scattering (SRS) microscopy to look for skin cancer. SRS lasers emit light that causes the molecules they encounters to vibrate. The vibrational patterns can indicate which compounds are present in the sample. However, in the past, those signals could only indicate certain classes of molecules, and thus were too broad to be of diagnostic use. Dantus and Xie’s team was able to narrow the specificity of the laser to the point where they could distinguish cholesterol from similar lipids.

The researchers expect to be able to use the same technique to identify cancer-associated proteins, as well as detecting traces of toxins. To be clear, this detection method requires neither contrasting dyes nor biopsy of the region to be tested. If this method proves effective, doctors will be able to diagnose skin tumors simply by shining a laser on the questionable area. The results would be almost instantaneous.

Tuesday, February 15, 2011

Lucy walked like a man

Lucy, the most well known member of the species Australopithecus afarensis, could apparently walk like modern humans. Carol Ward of the University of Missouri and William Kimbel and Donald Johanson from Arizona State University discovered an Australopithecus afarensis foot bone that shows clear evidence that Lucy had an arched foot.

This image shows the position of the fourth metatarsal Australopithecus afarensis (AL 333-160) recovered from Hadar, Ethiopia, in a foot skeleton.

Credit: Carol Ward/University of Missouri

Australopithecus afarensis lived about 3.2 million years ago. Anthropologists knew that the species was bipedal. In fact, much older hominids such as Ardi or Ardipithecus ramidus (4.4 million years ago) were known to have walked upright. However Ardi definitely had chimp-like grasping feet, ill suited for travel over flat ground. Until recently, no one knew what kind of feet Lucy had, and thus what kind of locomotion she could have employed. The discovery of the fourth metatarsal of an Australopithecus afarensis answered that question. With an arched sole and no grasping big toe, Lucy clearly walked upright on the ground like modern humans, rather than across tree branches as Ardi presumably did.

The foot bone was found in Hadar, Ethiopia, at a site referred to as the ‘First Family Site’. This rich site has yielded over 250 Australopithecus afarensis fossil specimens from at least 17 individuals.

Monday, February 14, 2011

Genes still jumping in the human genome

The human genome is far from fixed. Bits of DNA called SNPs (single nucleotide polymorphisms) and RIPs (retrotransposon insertion polymorphisms) have been moving around our genomes since well before we were human. More interestingly, they are still moving around today.

SNPs are simply single base changes in our DNA. For example, a person might have a A-T base pair in the middle of a gene, rather than a C-G base pair. This might make no difference or it could be the cause of a devastating disease. RIPs are much longer stretches of DNA that get plopped into the wrong place. You’d think, given the cell’s DNA correction machinery, such structural changes would be rare. Well, it depends on what you mean by ‘rare’. Haig Kazazian and Adam Ewing of Johns Hopkins University School of Medicine found over a thousand new RIPs not previously catalogued in human genome databases.

According to Kazazian:

We're not only discovering where they are and who has which ones, but also finding out that they insert with a remarkable frequency: On the order of one in every 50 individuals has a brand-new insertion that wasn't in their parents.

The researchers hope that these new insertions can be correlated with specific diseases or phenotypic traits. If so, that might help doctors develop treatments or cures. In any case, the prevalence of these mobile elements has implications for human evolution, both in the past and in the future.

Sunday, February 13, 2011

First extrasolar star system

NASA’s Kepler mission has successfully discovered over a thousand planets since its launch just over a year ago. Of those, around 70 are Earth-sized and 50 may be in the habitable zone (the proper distance from the sun for liquid water). To add to that, the Kepler space telescope recently discovered a complete ‘solar’ system around a distant star.

In Kepler-11, located 2000 light years from Earth, researchers have discovered the first star system to contain more than three planets. Kepler-11 has at least six planets, creatively named Kepler-11a through 11g. All are considerably larger than the Earth, and considerably closer to their star than the Earth is to the sun. The furthest out of the six, Kepler-11g, is only half as far away from its sun as the Earth is from the sun, and the other five orbit closer than Mercury does to the sun.

This artist's conception shows the Kepler-11 planetary system and our solar system from a tilted perspective to demonstrate that the orbits of each lie on similar planes.

Credit: NASA/Tim Pyle.

The planets were discovered using the ‘transit method’. For this technique to work, the planets must cross in front of their star from the perspective of the telescope. The miniscule drop in light caused by this transit yields information about the size of the planet and its orbit velocity. The six Kepler-11 planets appear to be rocky, though not in the habitable zone.

You can read a lot more about this extrasolar system on Phil Plait’s blog, Bad Astronomy.

Saturday, February 12, 2011

Changing skin cells into heart cells

The ultimate goal of studying stem cells is to be able to create any type of mature cell on demand. Sheng Ding led a team of researchers from The Scripps Research Institute and from the University of California, San Diego in advancing that goal. Their new technique takes less than a quarter the time and may be much safer.

Although it is possible to convert adult skin cells into other types of mature tissue, the process can take up to eight weeks, and that’s if one of your thousands of attempts is successful. That’s because the standard procedure requires first transforming the skin cell into a pluripotent stem (IPS) cell by inserting a set of four genes, and then from there into the desired cell type. Each of these steps takes weeks, and fails in most cases.

Ding’s team decided to try speeding up the process. They inserted the genes required to turn the skin cells into IPS cells, but rather than let that transformation continue to completion, it was interrupted after a few days (by inactivating the inserted genes). The scientists then gave the skin cells a signal to become heart cells. In just 11 days, they found beating heart cells in their Petri dishes.

Ding hopes to continue to streamline his protocol. In particular, he’d like to eliminate the need for the IPS genes altogether, since they’ve been linked to cancer. Going directly to the desired tissue type without going through an IPS step would be both faster and safer.

Here's a video explanation:

Friday, February 11, 2011

Just for fun: Doodling in Math

'Recreational mathemusician' Vi Hart has created a whole series of math-inspired doodle videos. You can visit her blog or youtube channel to see more videos like the example below.

Thursday, February 10, 2011

To prevent infection, use a checklist

Among the dangers associated with being seriously ill is the very real possibility of developing an additional infection in the hospital. In particular, an estimated 80,000 patients a year get infections from their central lines (plastic catheters placed into veins to administer drugs or fluids). To avoid these infections, Peter Provonost of Johns Hopkins University suggests that doctors use a checklist.

Provonost literally wrote the book on using medical checklists: Safe Patients, Smart Hospitals: How One Doctor's Checklist Can Help Us Change Health Care from the Inside Out. Based on his recommendations, Michigan hospitals began a five year long study called Keystone: ICU, in which doctors were asked to consult checklists before each procedure, and junior caregivers were given authority to question their superiors at any point. These seemingly simple steps resulted in a significant decrease in hospital mortality. At Johns Hopkins itself, central-line bloodstream infections dropped to nearly zero after implementation of Provonost’s protocols.

The idea of using medical checklists is gaining momentum. At first, some medical health professionals bristled at the idea that they needed to consult a checklist to remember to wash their hands or put on gloves. However, the data that show the benefits of following these procedures is compelling. Hospitals across the country are beginning to use this methodology with great success.

Wednesday, February 9, 2011

Bad news for using detection dogs

Dogs have been used to detect everything from drugs to cell phones. An enormous amount of trust is placed in their ability to accurately track down scents. Unfortunately, according to a new study by Lisa Lit, Julie Schweitzer and Anita Oberbauer of UC Davis, that trust may be misplaced.

To be clear, it isn’t the dogs’ ability to detect scents that is called into question, it’s how accurately they can relay that information. Lit and her colleagues found that the dogs routinely give their handlers the answers that the dogs thought their humans want.

The researchers set up a testing site with four rooms. The handlers were told that there could be up to three target scents (the scents to which the dogs had been trained to alert) in each room. In two rooms, there would be markers indicating where the scents were located. However, in reality, there were no target scents in any of the rooms. Two of the rooms did contain markers, but they were randomly placed. In addition, one of the rooms with markers and one without also contained distraction items: sausages and tennis balls.

Eighteen teams of dogs and handlers passed through each room twice. Despite the fact that none of the rooms contained any target scents, the dogs alerted a total of 225 times. Most of the alerts occurred at locations indicated by the markers. In other words, the dogs reacted more to their handlers’ expectations than to dog distractions like sausages.

This result should be troubling for any agency that relies on dog detection. There is no doubt that dogs are capable of accurately detecting all the things for which they are currently used. The question is whether their human handlers can be properly trained to avoid giving subconscious prompts that guide their dogs in the wrong direction.

In the meantime, perhaps we should look to other animals that care a lot less about what we think than dogs do. For example, Bart Weetjens has trained rats to detect landmines and to diagnose tuberculosis.