Science-- there's something for everyone

Thursday, June 30, 2011

Paralyzed man is able to stand

Thanks to Reggie Edgerton of UCLA, Susan Harkema of the University of Louisville, and their colleagues from UCLA, Caltech, the University of Louisville, and various medical institutes, a paralyzed man is able to stand on his own feet. The 26 year-old Rob Summers, who had been paralyzed from the chest down after a hit-and-run car accident in 2006, can now stand without external support for up to 25 minutes at a time.
The doctors implanted a 16-electrode array on Summers’ dura (the outermost membrane around the spinal cord). Although the injury had been between the C7 and T1 vertebrae (see diagram left), the electrodes were implanted far lower, in the L1 to S1 region. After several weeks of training Summers was able to support his own weight during electrical stimulation. He was not only able to voluntarily move his limbs but even regained some bladder, bowel and temperature control, an unexpected bonus of the treatment.
This technique had been successfully tested in animals, but this was the first successful trial in a paralyzed human. The research team has received approval to try the epidural stimulation procedure on four more patients.
You can watch the researchers’ explanation below.

Wednesday, June 29, 2011

Milky Way is full of orphan planets

Until recently, astronomers have assumed that planets are only to be found obediently orbiting their stars. Not so, according to an international collaboration led by Hiroki Sumi of Osaka University. Apparently, not only are there planets roaming around the galaxy with no host star, but they may outnumber stars by two to one.

The astronomers used a technique called gravitational microlensing to find the wayward planets. Briefly, as a closer object (like a planet) passes in front of a distant bright star, the gravity of the closer object affects the light coming from the distant star. Thus far, ten Jupiter-sized rogue planets have been detected, but the scientists extrapolate that there may be as many as 400 billion star-less planets in our galaxy.

Artist's concept of a free-floating planet

This artist's conception illustrates a Jupiter-like planet alone in the dark of space, floating freely without a parent star. Astronomers recently uncovered evidence for 10 such lone worlds, thought to have been "booted," or ejected, from developing solar systems.
Image credit: NASA/JPL-Caltech.

Where did these homeless planets come from? If current theories about planetary formation are true, namely that planets form from the dust swirling around proto-stars, then these orphan planets must have been flung out of their stellar systems, perhaps due to collisions. On the other hand, there may be a completely different mechanism for planet formation that does not involve orbiting any stars.

To be clear, just because a planet does not orbit a star does not mean that it can wander aimlessly about the galaxy. Like the stars in the Milky Way, such planets would eventually fall into stable orbits around the center of the galaxy.

For more details, check out Phil Plait’s Bad Astronomy blog.

Tuesday, June 28, 2011

Bad news for sick space travelers

According to new research led by Jean-Pol Frippiat of Nancy-University (Vandœuvre-lès-Nancy, France), space travel may compromise antibody production. Apparently, zero gravity conditions can decrease the variability that makes antibodies so powerful.

Our immune systems rely heavily on the fast diversity of our antibodies to attack any foreign invader we might encounter. In addition to the variability that is built into the manufacture of antibodies (which can be put together in a great many combinations), antibody genes also mutate at extremely high rates. Now it seems that the hypermutation of antibody genes is decreased during extended periods at zero gravity.
The researchers compared three groups of the amphibians Pleurodeles waltl (known to produce antibodies the same way that humans do). One group of the newts was immunized on Earth, one in space, and one not at all. The space group showed a lower frequency of mutation than the Earth-bound group. This could mean that human space travelers will have a harder time fighting off infections.  On the other hand, astronauts will probably only have to contend with their own germs anyway, not new ones.

Monday, June 27, 2011

Early archosaur reclassified

A 250 million year old fossil that was thought to belong to a creature that lived before birds and crocodiles branched off from each other has now been found to belong securely to the crocodile branch of the tree, according to Sterling Nesbitt of the University of Washington and his colleagues Jun Liu of the American Museum of Natural History in New York and Chun Li of the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing. The researchers examined the fossil remains of Xilousuchus sapingensis and found that it has more in common with crocodiles than with birds.

As you can see from the cladogram below, birds and reptiles shared a common ancestor.  Somewhat more surprisingly, this diagram also shows that crocodiles are more evolutionarily similar to birds than they are to lizards, and that birds form a subgroup within reptiles. Creatures within the entire group of reptiles, including birds, are classified as archosaurs.

File:Tuatara cladogram.svg
1. Tuatara
2. Lizards
3. Snakes
4. Crocodiles
5. Birds
By Benchill, Nov. 8, 2007

The most interesting thing about this reinterpretation of the X. sapingensis fossil, is that it places the crocodile/bird divide further back in history. The largest extinction in Earth’s history (in which 95% of marine life and 70% of land dwellers perished) occurred at the end of the Permian period 252 million years ago, or just before X. sapingensis lived. Does this mean that archosaurs had diverged into bird and crocodile lines before that extinction event, or afterwards?  If before, it means that each of the subgroups shown above had to have survived the extinction event.  If after, the subgroups would have had to have separated from each other within a few million years.  And thus, scientific debate goes on.

This is a reconstruction of X. sapingensis, based on the fossil.
Credit: Sterling Nesbitt

Sunday, June 26, 2011

Leprosy from armadillos

Of the 150 or so new cases of leprosy (a bacterial infection caused by Mycobacterium leprae) diagnosed in the United States each year, about a third are acquired from inside the country. Researchers from the Global Health Institute at EPFL and from Louisiana State University have now confirmed the source of those infections. Leprosy is carried and transmitted by armadillos.
Those familiar with both the disease and with armadillos probably aren’t surprised. After all, armadillos have been known to carry leprosy for decades. Armadillos, with their body temperature of 89° F, are well suited to harbor M. leprae, which require a temperature of between 86° F and 89° F (30° C to 32° C). Most people are only this cool at their extremities (where leprosy tends to attack).
In this study, genetic analysis was used to compare the exact strain of leprosy in human patients and in armadillos. The same unique strain of M. leprae was found in 28 out of 33 wild armadillos and in 25 out of 39 human patients living in proximity with the armadillos, indicating a clear connection.
Leprosy is actually not that easy to contract. Over 90% of people who are exposed to leprosy will fight it off without treatment, and those that do become ill can be cured with modern antibiotics. Nevertheless, the authors conclude:

Frequent direct contact with armadillos and cooking and consumption of armadillo meat should be discouraged.

Sounds reasonable.

Saturday, June 25, 2011

Just for fun: Liquid metal

David Dietle posted an article on showcasing seven totally bizarre man-made substances.  Here's one of them: a ferrofluid. These colloidal solutions of water or solvent, iron nanoparticles and surfactant react strongly to magnetic fields.  Observe:

A ferrofluid sculpture by Glenn Gould.

Friday, June 24, 2011

Pharmacies may not catch harmful drug interactions

University of Arizona pharmacologists have tested currently employed tools for assessing whether pharmacies catch and prevent harmful drug interactions. In many cases, the frightening answer is that they don’t.
The researchers, led by Daniel Malone, brought prescriptions written for fictitious patients to 64 Arizona pharmacies. Among the 18 prescriptions presented, 13 could have caused clinically significant adverse drug interactions. Only 18 out of the 64 pharmacies correctly identified the problematic drug combinations. Obviously, a better system is needed.
There are computer systems that can identify dangerous drug interactions, but they aren’t always available. The authors suggest that an ideal system would require:
  • software that allows for customization
  • standard policies for handling specific interactions
  • and drug knowledge databases that are updated frequently.

In the meantime, make sure you tell your doctor about all the medications you are taking, especially if she prescribes a new one.

Thursday, June 23, 2011

Advances in metallic glass manufacture

Glass is created by cooling a material to its solid state without allowing it to crystallize, but instead while maintaining a liquid-like flow of atoms. In contrast, the atoms in metals have a neatly arranged crystalline structure. Metallic-glass alloys are non-crystalline solids that contain metallic elements such as zirconium, titanium, copper, or nickel. Such alloys are strong and light, compared to other materials. Unfortunately, they have been difficult to manufacture.
If you’ve ever watched a glass-blower, you know that the artist usually has several minutes to shape the glass before it solidifies. Not so with metallic-glasses which will begin to crystallize almost immediately. The trick then, is to melt the metallic glass (which requires temperatures above 500 degrees Celsius), achieve the desired shape, and then refreeze the glass before it has a chance to crystallize.
William Johnson and his colleagues from Caltech have devised a new strategy for processing metallic-glass. They used Joule heating (also called ohmic heating or resistive heating) to rapidly heat a rod of metallic-glass via an electric current. The entire process takes only milliseconds, ensuring uniform heating and non-crystalline cooling.
A metallic-glass rod before heating and molding (left); a molded metallic-glass part (middle); the final product with its excess material trimmed off (right).
Credit: Marios D. Demetriou.
Meanwhile, Jan Schroers team from University has found a way to blow mold metallic glasses. They’ve been able to create all sorts of complex shapes.

Jan Schroers and his team have developed novel metal alloys that can be blow molded into virtually any shape.
Credit: Image courtesy of Yale University.

In all, the metallic-glass field is looking more and more promising.

Wednesday, June 22, 2011

Human language arose in Africa

Update 2/12
This data has since been disputed by Michael Cysouw and Steven Moran from Ludwig Maximilian University and Dan Dediu from the Max Planck Institute.  They claim that Atkinson's conclusions are based on faulty methodology and artifacts.

It’s well established that the human species as we know it today evolved in Africa and migrated out across the world some 200,000 years ago. However, it has never been clear exactly when and where hominids developed the gift of language. According to a study by Quentin Atkinson of the Universities of Auckland and Oxford, speech developed before that great migration.
Today, every human culture has language, many of which are astoundingly, or should I say incomprehensibly, different from one another. Did such languages arise totally independently after humans left Africa, or are all languages ‘evolved’ from an African predecessor? Atkinson used the same sort of methods to trace the origins of languages as have been used to follow biological evolution. He sampled the phonemes (roughly, verbal sounds) used in 504 different languages around the worlds and found that the pattern of variation in phonemes exactly matched the pattern of genetic diversity in humans.
 Africans have the greatest variation in both phonemes and DNA, the more recently settled areas (Europe and Asia) have more moderate variation in both, and the fewest phonemes and least genetic diversity were found in South America and on Pacific islands.

Language Map of the World
Map courtesy of used with permission.

This strongly suggests that language, like humans themselves, originated in Africa. A subset of those humans left Africa, taking their local language with them. As humans spread throughout the world, they continued to take only the particular phonemes they needed to each new location. When they reached islands such as Hawaii, for example, their total phonemic inventory had been whittled down to just over a dozen.

Tuesday, June 21, 2011

Solar powered autoclave

Engineering students at Rice University have devised a method of using solar power to sterilize medical instruments. Their device, an autoclave version of a solar cooker called the ‘Capteur Soleil’ (invented three decades ago by Jean Boubour), successfully killed biological specimens left on tools.

Many medical tools are steam-sterilized in autoclaves (essentially metal boxes built to withstand high pressure steam). Medical waste can also be sterilized in autoclaves prior to disposal. Industry standard requires an autoclave to be held at 121 degrees Celsius for at least 30 minutes to achieve sterilization.

The Capteur Soleil consists of a series of curved mirrors that focus the sun’s energy to turn water into steam. The Rice students’ innovation was to force that steam through a modified hot plate, which in turn heats up the instrument-containing autoclave. Once the mirrors are aligned properly, it takes about an hour for the hot plate to reach sterilizing temperature, and another half hour to kill spores.

For their senior capstone design project, the members of Team Sterilize refitted the Capteur Soleil at Rice's Oshman Engineering Design Kitchen to sterilize medical instruments and supplies with the power of the sun. From left, David Luker, William Dunk, professor and team adviser Doug Schuler, Daniel Rist and Sam Major.
Credit: Jeff Fitlow/Rice University.

This device would obviously be a boon to communities without the fuel resources required to sterilize medical equipment. According to the students, any type of autclave can be placed in the system, and of course, everything is reusable.

You can see an explanation by the students below.

Monday, June 20, 2011

More information about wrong way planets

previously mentioned that some exoplanets do not orbit their stars in the same direction as the star itself is rotating. The number of these ‘wrong-way planets’ has now increased significantly. About a quarter of all extrasolar 'hot Jupiters' (Jupiter-sized planets that orbit very close to their stars) orbit in the opposite direction of their star’s spin. Smadar Naoz and her colleagues from Northwestern University may have found out why.
Hot Jupiters are thought to form far from their stars (about where our Jupiter is within the solar system) and then migrate inward due to forces from other planets. The Northwestern researchers modeled a system in which a Jovian-sized planet is joined with another planet even farther out. Over long periods of time, the Jovian planet is nudged closer to its star. In some cases, the tidal effects of the second planet can cause the Jupiter-like planet to first achieve a highly elongated eccentric orbit, and then to flip and start rotating in the opposite direction.

A retrograde hot Jupiter: the transiting giant planet orbits very close to the star and in a direction opposite to the stellar rotation. This peculiar configuration results from gravitational perturbations by another much more distant planet (upper left).
Credit: Lynette Cook

Prior to the discovery of hot Jupiters and retrograde orbits, we thought our solar system was the standard model for star system formation and appearance. Now we know that there’s a lot more variety out there than we thought. Which is all to the good, in my opinion.

Sunday, June 19, 2011

Universal grammar

Linguists and cognitive scientists have long noticed two things about human language. First, all but the most severely mentally disabled children learn at least one language with ease, and second, almost all human languages fall into a few broad grammar categories. It has long been thought that these two aspects are related. That is, that the human brain is prewired with a few possible grammar constructs, and that babies have only to identify the type of language around them.
A new study by Jennifer Culberston, Paul Smolensky and Geraldine Legendre of Johns Hopkins University provides further evidence for a ‘grammar center’ of the brain. The scientists took advantage of some common grammar factors that distinguish different languages. For example, some languages, such as English, place the adjective in front of the noun (blue car), whereas others, like French, reverse that order (voiture bleue). Both French and English place numbers in front of nouns (trois chats, three cats), but other languages (such as Pumi, a language spoken in China) place the noun in front of the numeral.

The researchers used a video game to teach English-speaking adult volunteers a series of artificial languages. In some cases, the languages had word order combinations that corresponded to known human languages, but in one case (the language ‘Verblog’), adjectives preceded nouns but nouns preceded numerals, a virtually unheard of combination. The English-speaking participants had no trouble with artificial languages following either English or French rules of noun/adjective order. However, they had a great deal of trouble learning Verblog. The authors suggest that Verblog could not be made to fit the subjects’ prewired grammar expectations.

Saturday, June 18, 2011

Just for fun: Flight patterns

Award winning digital artist Aaron Koblin created this beautiful graphic of airline flight paths.

You can watch Koblin's TED talk here.

Friday, June 17, 2011

Pigeons perceive like humans

Humans expend a great deal of cognitive energy on recognizing both faces and the emotional content of those faces. However, according to a study by Fabian Soto and Edward Wasserman of the University of Iowa, this ability is not unique to humans. Pigeons can do it too.

Pigeons do not have a specialized system for face processing, but they still show similarities to people when they are trained to recognize human faces. (Credit: U. Iowa).
When shown an array of human faces displaying different emotions, pigeons could categorize the pictures according to either identity or emotional content. Even more intriguingly, they showed the same biases that humans show. It’s much easier for people to group all pictures of a single individual together regardless of facial expression than it is to group pictures with similar emotional expressions regardless of identity. It’s believed that this discrepancy is a direct result of our specialized human face recognition system. Why then are pigeons equally better at grouping individuals by identity than by facial expression? The authors suggest that our facial recognition abilities, far from being unique to humans, may be shared by all vertebrates.
Wasserman states:

We hope that our research will prompt other researchers to conduct more comparative work to assess their claims about the evolution of uniquely human perceptual and cognitive processes.

Thursday, June 16, 2011

Losing early memories

Most people cannot remember much that happened during their first few years of life. Carole Peterson, Kelly L. Warren, Megan M. Short of Memorial University of Newfoundland wondered whether ‘infantile amnesia’ affected children as well as adults. They found that the earliest memories are lost within the first few years.

The researchers asked a group of 140 children aged four through thirteen about their three earliest memories. The age at which the events occurred was corroborated by the children’s parents. Two years later, the scientists asked those same children to again describe their three earliest memories. The youngest children in the study (initially aged 4 to 7) had three new earliest memories with very little overlap with what they had described the first time around. In contrast, children who had been at least ten at the first interview did provide the same earliest memories about half the time. Apparently, early memories are lost not long after they are made.

According to Peterson:

Younger children's earliest memories seemed to change, with memories from younger ages being replaced by memories from older ages. But older children became more consistent in their memories as they grew older.

Wednesday, June 15, 2011

Why do blind people have a superior sense of touch? Practice!

Blind people are known to have an enhanced sense of touch compared to sighted people. But what is the cause of this increase in tactile ability? The two top theories are that the blindness itself rewires the brain so that more processing power is applied to the touch centers, and that blind people simply make greater use of their sense of touch. Michael Wong, Vishi Gnanakumaran, and Daniel Goldreich of McMaster University have shown that the latter hypothesis is true: blind people have a greater sense of touch because they practice touching things more often.

The researchers compared 28 profoundly blind people with 55 normally sighted people. Some of the blind participants were proficient in reading Braille. All the volunteers were tested for touch sensitivity on various fingers as well as on their lower lips. If blindness itself led to a increased sense of touch, the blind people should have been more sensitive than the sighted people everywhere on their bodies, including on their lips. This wasn’t the case. Instead, the researchers found that blind people were more sensitive on their fingers than sighted people but all participants were equally sensitive on their lips (which presumably are used equally by both blind and sighted people). In addition, blind people who could read Braille had more sensitive fingers than blind people who could not, and among the Braille readers, the finger they used to read with was more sensitive than their other fingers.

Taken together, these data clearly show that it’s increased usage that leads to increased sensitivity. There was even a direct correlation between the number of hours spent reading Braille and reading-finger sensitivity. As with everything else, practice makes perfect!

Tuesday, June 14, 2011

Calorie restriction may not lead to longer life after all

There have been numerous animal studies showing that extreme calorie restriction can slow aging and increase longevity. For the first time, researchers from the University of Texas Health Science Center and from the University of Colorado have challenged this assertion. Their studies on mice have shown that dietary restriction (DR) can sometimes shorten lifespans, rather than lengthening them.
The scientists used 41 discrete inbred strains of mice. The different strains showed a variety of responses to DR with some strains living longer and some shorter. Upon closer examination, the researchers found that those strains that had lost the most fat during the DR treatment had the shortest lifespans. Conversely, the mice that were able to hold onto their fat even under conditions of reduced calorie intake lived the longest.

These data do not contradict the many studies showing that DR does in fact lead to longer lives. Those results are well documented. However, these results calls into question how much variability there may be in the efficacy of the DR regiment within species. So don't start starving yourself yet.

Monday, June 13, 2011

Germ Genie for keyboards

Computer keyboards are notoriously germy and difficult to sanitize. To solve this problem, Duncan Louttit (founder of Falcon Innovations) invented the Germ Genie, a standup UV light source with a built in motion sensor. University of Hertfordshire researchers have found the product highly effective in killing common bacterial pathogens.
The Germ Genie is placed behind a keyboard so that the UV light emanating from it can cover the entire keyboard. Once the device detects no movement over the keyboard for a minute, the UV light is activated for one minute. Ten of these one-minute treatments can eliminate 99% of E. coli, Staphylococcus aureus and Bacillus subtillis from a standard keyboard. Even more important, longer periods of Germ Genie usage also killed Clostridium difficile, a deadly and difficult to kill pathogen. The Germ Genie’s motion sensor turns off the UV lamp if someone resumes typing during the one-minute treatment cycle, preventing UV irradiation of the hands.

Germ Genie.
Credit: Image courtesy of University of Hertfordshire.

It’s easy to see how this device could completely sanitize a home computer keyboard. Even if a keyboard is used by someone who is ill, there will be enough typing breaks throughout the day to sanitize the keyboard. However, the inventers of Germ Genie are hoping to market their device to hospitals and offices where multiple people use the same keyboard throughout the day. I’m not sure you’d get enough UV cycles between users to completely disinfect a keyboard. The way I understand it, the first person might have to type and take a quick break up to ten times before the next person used the keyboard. On the other hand, even one UV cycle significantly reduced the number of bacteria on the keyboard. Over all, it’s a great idea, and well worth further testing.