Science-- there's something for everyone

Tuesday, January 31, 2012

Meet the X prize

You may be familiar with the Ansari X PRIZE, awarded to the first private team to build a spacecraft capable of taking three people to 100 kilometers above the surface of the Earth.  Burt Rutan and Paul Allen took that $10 million prize in 2004 for their SpaceShip One. 

SpaceShip One in flight, from Rokits XPrize gallery.

However, you may not know that the X PRIZE Foundation has lots of other huge prizes for meeting technological challenges.  For example, they offer $10 million for rapid and accurate human genome sequencing, $1 million for cleaning up oil spills, and $30 million for the first private team to send a robot to the moon.  There’s also a $10 million prize for building a medical tricorder like the ones on Star Trek. 

In each case, the X prize is designed to encourage engineers and scientists to push the limits of what's possible.  The tricorder X prize is no exception. On the TV shows, doctors wave a small instrument over a patient’s body and instantly know all that ails him.  The prize-winning apparatus would have to diagnose at least 15 diseases and weigh no more than five pounds.  The task of creating such a device may not be as daunting as it seems.  Researchers from the Singapore Agency for Science, Technology and Research and from the Imperial College London may be on their way to collecting the prize by developing a new way to create electromagnetic Terahertz waves (T-rays).   T-rays are often used in airport scanners, and could be modified for use in medical scanners as well.

I hope all these prizes do get awarded.  When they do, we all win.

Monday, January 30, 2012

Tiny wasp will travel

A few months ago, I wrote a post about how some fairyfly wasps had managed to shrink to lilliputian sizes by shedding nuclei.  Although this wasp (Gonatocerus ater) is much larger (though still miniscule), it too had a trick up its antenna.  It made its way across the country in less than a year.

Gonatocerus ater.
Credit: Jason Mottern, UC Riverside Department of Entomology.
In August, 2010, the first North American specimen of this species was discovered by Serguei Triapitsyn (principal museum scientist from the University of California, Riverside) in upstate New York.  By August, 2011, it was found in Irvine, California.  Three thousand miles is pretty far to travel in one year when you’re only a millimeter long.  That’s almost 5 billion body lengths. If the tiny insects had journeyed under their own power, they’d have had to move millions of body lengths each day, the equivalent of a six-foot man traveling well over ten thousand miles a day.  Of course, it’s much more likely that G. ater hitched a ride to the west coast, just as it originally must have done from Europe.

The good news is that G. ater isn’t likely to be an ecological threat, and may even be a boon.  Like all fairywasps, G. ater makes its living by laying its eggs inside the eggs of larger insects. I’m sure I don’t need to tell you what happens to the hosts. In this case, the victim of choice is most likely a leafhopper (Rhytidodus decimaquartus), a pest that feeds on Lombardy poplar trees.  In fact, the researchers suggest that G. ater was transported within leafhopper eggs that were themselves attached to sticks.

Sunday, January 29, 2012

The sex life of fungi

Fungi don’t have physical differences in gender the way animals do.  Instead, they have specific regions of their genomes that code for sexual identity.  These sites determine with which other fungi they are compatible.  But here’s the rub:  there can be more than just two forms of mating type genes (alleles), so fungi can have more than two sexes.

Ronny Kellner and Dominik Begerow from Ruhr-Universität Bochum and Evelyn Vollmeister and Michael Feldbrügge from Heinrich-Heine University Düsseldorf have been studying a type of parasitic fungus called a ‘grass smut’.  This fungus parasitizes grass crops such as wheat, but only after mating.  Thus, grass smuts must find compatible sexual partners before they can proceed through their life cycle.  Fortunately for them, they have three distinct mating types.  To be clear, this does not mean that the fungi require two partners to procreate, but rather that each fungus can successfully mate with either of the other two sex types.

And that's not a grass smut's only reproductive advantage.  They can also successfully mate across species lines.  That may not seem unusual until you note that the species in question diverged over a hundred million years ago, which is about how long ago humans diverged from elephants.  This loose sexual selection gives the fungus access to more genetic variety, which can allow it to parasitize more freely and to evade biological counterattacks.

In case you think having three sexes is extreme, you may want to consider the fungus Schizophyllum commune.  Because S. commune has close to 400 different mating genes spread between two locations on its genome, this little organism comes in about 28,000 sexual forms, each of which can mate with any other form. 

Saturday, January 28, 2012

Google Flu Trends for the win

Update 3/29/14: 
Okay, not so much. In reality, Google Flu has been a bit of a disaster. It turns out that when people self diagnose themselves with flu, they're wrong at least 80% of the time. Which of course means that people who do Google searchers on influenza hardly ever actually have the flu. Oops.

Google Flu Trends (GFT) is a tool for predicting where and when the flu will strike, based on the number of people doing Google searches for flu-like terms and symptoms.  The number of flu searches correlates surprisingly well with the number of actual flu cases.  In fact, a new study led by Andrea Dugas of Johns Hopkins showed that GFT could predict emergency room visits.

Traditionally, doctors’ offices and hospitals rely on reports from the Centers for Disease Control (CDC) to prepare for influxes of flu patients.  Because these reports are based on actual hospital admissions and laboratory tests, by the time a community hears from the CDC about flu epidemics in their area, it may be too late.  In contrast, clinicians can access the data from GFT in real time.  A regional spike in interest in the flu tells local health care providers to prepare for incoming flu patients.

Like citizen science projects, GFT relies on the power of the community of internet users.  However, unlike other projects, participants don’t need to sign up for anything or get any kind of instruction.  Simply by using Google however they like, they end up advancing science and benefiting their neighbors.  It makes me feel all warm inside.

Friday, January 27, 2012

Why primates don’t all look alike

As you can see from the illustration below, primate faces are extremely variable. Sharlene Santana, Jessica Alfaro and Michael Alfaro of the University of California, Los Angeles were interested in how that diversity came about.  They found that both local environments and population size were driving factors in facial evolution.

Eleven species of Neotropical (Central and South American) primates were compared.  In each case, two to ten photographs of adult males were studied.  Each face was divided into fourteen sections which were graded for colors and patterns of hair and skin.

Primates from Central and South America. (1) Cacajao calvus, (2) Callicebus hoffmansi, (3) Ateles belzebuth, (4) Alouatta caraya, (5) Aotus trivirgatus, (6) Cebus nigritus, (7) Saimiri boliviensis, (8) Leontopithecus rosalia, (9) Callithrix kuhli, (10) Saguinus martinsi and (11) Saguinus imperator.
Illustrations by Stephen Nash, courtesy of University of California - Los Angeles.

Interestingly, they found that primates that live in small groups have more complex facial patterns (varying colors, alternating areas of hair and skin) than those that live in large social groups. As Santana says:
We found very strong support for the idea that as species live in larger groups, their faces become more simple, more plain.
In case you’re wondering what this says about humans, by the criteria of this study, we have extremely plain faces.  But don’t feel bad.  The authors suggest that plainness correlates with expressiveness.  Emotional content can be read more easily on a plain face, which is much more important for individuals living in large groups.

Among the additional findings, species that live near other members of the same genus had more complex facial features than primates with no closely related neighbor species.  Presumably, this helps to avoid hybridization between similar species. Also, colorization of specific facial regions correlated well with latitude and forestation.  Monkeys living at higher latitudes had lighter crowns but darker nose and mouth patches than those at lower latitudes, those in forested regions had darker crowns and eye patches than those in open areas.

Taken together, the data suggest that facial differences did not arise by random chance but are selected for based on behavior (group size) and location.  

You can see a slide show of monkey faces (not necessarily the ones in this study) presented by BBC Nature here.

Thursday, January 26, 2012

HPV vaccine does not cause autoimmune disease

The human papillomavirus (HPV) is responsible for virtually all cervical cancers, and for some other cancers as well.  Fortunately, there is now a vaccine (called HPV4, because it contains antigens to four major types of HPV) that can prevent those diseases.  You may know the vaccine by its trade name Gardasil.  Thus far, it has had an outstanding record of safety and efficacy.  Thanks to a new study conducted by Kaiser Permanente researchers, we can now also eliminate any connection between HPV4 and sixteen different autoimmune diseases (AID), including lupus, Guillain-Barré syndrome and rheumatoid arthritis.

Researchers examined the medical records of almost 200,000 young women who received at least one dose of HPV4 from 2006 to 2008.  The subjects were followed for six months after each injection for signs of AID.  The number of new cases of AID during any time period was the same for vaccinated and unvaccinated women, strongly indicating that the vaccine had no effect whatsoever on the development of AID. 

Oh, and by the way, HPV4 doesn’t cause mental retardation either.

Wednesday, January 25, 2012

Just for fun: Digitizing books with reCAPTCHA

Luis von Ahn of Carnegie Mellon not only invented captcha (those exasperating squiggly words that tell websites you are a human), he reinvented it.  ReCaptcha is now a tool for digitizing books.  Ever since I learned that, I've found them much less annoying.  Well, okay, a bit less annoying.

Here's an excerpt from NOVA ScienceNow explaining reCaptcha.

You can watch von Ahn's TED talk here.

Tuesday, January 24, 2012

New magnetic bacteria

Magnetotactic bacteria produce magnetic crystals within their cells. They use these crystals to orient themselves, but we can use them for drug delivery and medical imaging.  Up until now, scientists have only been able to culture bacteria that produce magnetite (iron oxide) crystals.  For the first time, Dennis Bazylinski at the University of Nevada and his colleagues have been to grow bacteria that can also produce greigite (iron sulfide)  crystals

Bacteria BW-1 were isolated from deepwater samples in Badwater Basin, Death Valley National Park. They have the genes to make either magnetite or greigite crystals, a useful advantage in the uncertain environment in which it finds itself.  Because iron oxides have slightly different properties than iron sulfides, BW-1 may turn out to be more useful than standard magnetotactic bacteria.

Below are some magnetotactic bacteria swirling back and forth as an external magnet is moved (you may need to watch this clip on youtube).

Monday, January 23, 2012

Are marathons bad for your heart?

In most cases, the answer is no.  However, researchers led by Andre La Gerche of the University of Melbourne have found that endurance exercise (marathons, alpine bike races and triathlons) can damage the right ventricles of a small subset of athletes. To be clear, this study did not address sudden cardiac arrest during a race, for which marathoners are at no greater risk than any other athletes.  Rather it looked at whether asymptomatic damage could be detected in extreme athletes.  The short answer is that although such damage does occur, it seems to be reversible for most people.

Forty experienced volunteers (having finished in the top 25% of a recently competed race) with no known heart problems were asked to run a race for science. Each person had complete heart work-ups a few weeks before the race, within an hour of finishing, and about a week later.  The tests included cardiac MRIs, echocardiographs and blood tests.

Immediately after intense endurance exercise, the athletes did show changes in the shape and function of their hearts.  Specifically, they had a significant reduction in function in their right ventricles, which was corroborated by biomarkers in the blood tests. The left ventricles did not appear to be affected, which was consistent with previous studies showing that the right ventricle is under greater stress than the left during intense exercise.

The good news is that for most of the athletes, that change was completely reversed by the one week follow up.  Only one out of eight people still showed signs of damage at that time. And those people may have simply required a slightly longer recovery time.

The researchers are quick to point out that their small study in no way negates the positive effect of exercise on human health. 

To draw an analogy, some tennis players develop tennis elbow. This does not mean that tennis is bad for you; rather it identifies an area of susceptibility on which to focus treatment and preventative measures. 
So, to summarize, this study may just indicate that ultra-athletes should give their hearts time to recover between events.  However, just to be on the safe side, I’ve decided to forego running marathons.

Sunday, January 22, 2012

MRNA kill switch

One of the ways in which cells regulate their metabolic functions is to control how much of each protein is made. Robert Singer and his colleagues from the Albert Einstein College of Medicine and the National Cancer Institute have found that some mRNAs have an internal ‘stability switch’ which causes them to decay when no longer needed.

First, a molecular biology primer. Very briefly, DNA contains genes that code for proteins.  Those genes are transcribed into mRNA, which is then translated into protein.  The amount of each protein that can be made depends largely on the number of mRNA strands that are available.  To immediately stop protein production, a cell would have to eliminate any existing mRNA strands. 

The researchers used the proteins Clb2 and Swi5 because they are tied to the cell cycle. In fact, the mRNA transcripts of these proteins decay 30 times faster during mitosis (cell division) than at other times. To figure out what was causing the CLB2 and SWI5 mRNAs to self-destruct so rapidly, the researchers tried swapping bits of those genes with bits from other genes whose mRNAs don’t decay during mitosis.  Surprisingly, swapping the internal regions of the genes (the part that tells which amino acids will be in the protein) had no effect, but replacing the promoter (the start code for RNA transcription) completely changed the mRNA turnover rate. 

The researchers suggest that as CLB2 and SWI5 are being transcribed, a specific factor is loaded onto the mRNA strand that, under the right environmental signals, initiates decay of that transcript.  In other words, each mRNA strand carries its own kill switch along with it.  Although this work was done on yeast cells (using a fluorescent microscopy technique that allowed the scientists to label and observe individual mRNA molecules), it could have implications for human cell division diseases like cancer.

Saturday, January 21, 2012

New fronts in the war against malaria

Over the past year, there’s been some encouraging work done on preventing malaria, a disease caused by a parasitic protozoan (Plasmodium) with a complicated lifecycle involving both human and mosquito hosts (see video below).

Here are just three of the many drug or vaccine targets under current investigation, all involving Plasmodium falciparum, the species responsible for the most lethal form of malaria.  Nine out of ten of the hundreds of thousands of annual malarial deaths can be attributed to this little pest.

Joseph Jez of Washington University and his colleagues have isolated a membrane protein (phosphoethanolamine methyltransferase, or PfPMT) that is critical for the growth and survival of P. falciparum within human blood cells. Not only did Jez and his team isolate the protein, but they were also able to determine its exact structure and function. Even more importantly, this particular protein is not found in mammals, making it an ideal drug target. 

University of Oxford biologists led by Alexander Douglas have identified a different blood-stage antigen (reticulocyte-binding protein homologue 5, or RH5) that, unlike most of the other P. falciparum proteins, is highly conserved among all strains of the protozoa.  This means that an immune response generated against this protein should be effective against all strains of the bug.  Scientists have begun testing a vaccine against this particular protein with promising results thus far. 

Finally, David Cavanagh and his colleagues from the University of Edinburgh chose to focus on merozoite surface protein 1 (MSP-1), a protein that makes up about 40% of the surface area of the merozoite life stage of P. falciparum.  Because MSP-1 is highly variable the researchers constructed an artificial gene containing elements from all the major types of the proteins.  In animal tests, this elongated hybrid protein produced a good immune response.

Friday, January 20, 2012

Deep-sea vent discoveries

An international team of scientist explorers, led by Douglas Connelly of the National Oceanography Centre, Southhampton, UK and Jonathan Copley of the University of Southhampton, have discovered two new deep-sea hydrothermal vent fields.  The first is the deepest and hottest to date, and the second is in a place no one thought to look before.

Both hydrothermal vents are located on the Caribbean Sea floor.  The first, dubbed the Beebe Vent Field (after Charles William Beebe, the first scientist to descend to the deep sea), is almost five kilometers down in the Cayman Trough.  The plume of smoke that rises from its chimneys goes up over a thousand meters, suggesting that water is exiting the vent at close to 500°C.

Next to the Cayman Trough is an undersea mount called Mount Dent.  If transported to land, Mount Dent would rise almost three thousand meters.  As it is, the summit of Mount Dent is still a few thousand feet below sea level.  A second set of hydrothermal vents (named the Von Damm Vent Field after Karen Von Damm, a renowned marine geochemist) has been found on the upper slopes of this mountain, a location thought to preclude that possibility.

Prior expeditions to deep-sea vents have yielded creatures unknown to science, and this enterprise was no exception.  The team discovered a new species of shrimp with no eyes but with a light-sensing organ on its back.

The scientists present the following videos of their discovery.  Note:  HyBIS is the name of the deep-sea submarine, and also the name given to the new shrimp, Rimicaris hybisae.

Thursday, January 19, 2012

Stem cells are in the eyes of the beholder

And in everyone else’s eyes as well.  According to new research led by Sally Temple and her colleagues from Rensselaer, our retinal pigment epithelial (RPE) cells not only allow us to see, but also harbor multipotent stem cells.

The RPE, shown at the bottom of the retina (pigmented layer), is made up of a single layer of pigmented cells.  These cells are essential for nourishing the light sensitive photoreceptors within the retina.  Among their other talents, entire retinas can be regrown from a few RPE cells… At least in salamanders.  Of course, salamanders can also regenerate entire limbs.  Nevertheless, Temple and her team set out to determine whether human RPEs could be induced, if not to entirely regrow retinas, at least to repair them.

The researchers obtained RPE cells from cadavers ranging from 22 to 99 years old at the time of death.  After trying assorted growth mediums, they discovered that about ten percent of the cells had the ability to differentiate into a variety of cell types, including neurons and bone cells.  This was true even for cells derived from eyes that had been nearly a hundred years old.

Needless to say, this work has implications for treating many diseases, not the least of which is retinal repair. Before you despair that you’d have to be a cadaver to benefit from this, you should know that RPEs can easily be removed from living persons as well. 

You can literally go in and poke a needle in the eye and get these cells from the subretinal space.

Tuesday, January 17, 2012

Art is in the label of the expert

Here’s a story that should surprise no one:  people react differently to art depending on whether they believe it is authentic or fake.  But did you know those differences are visible in brain scans?

Researchers from the University of Oxford placed 14 participants (labeled ‘human participants’ in the paper, no doubt to avoid provoking the wrath of the NIH over inappropriate use of chimpanzees) in an fMRI brain scanner while they viewed 50 portraits, half of which were painted by Rembrandt and half of which were fakes.  Each image was accompanied by the verbal description ‘authentic’ or ‘copy’ regardless of the actual nature of the painting.  In fact, half the paintings were mislabeled.  As the volunteers were not art experts, they presumably believed whatever description was given for each portrait. In any case, different regions of their brains were activated when they viewed what they believed to be forgeries regardless of the actual origin of the piece.

If this is true, I’m going to attempt to delude myself into thinking every art piece I encounter has been crafted by a grand master.  I plan to start with anything created by my daughter.

Monday, January 16, 2012

Researchers to stop using chimpanzees

The National Institutes of Health (NIH) has decided to all but eliminate the use of chimpanzees in biomedical or behavioral studies.  This decision follows the release of a new report from the Institute of Medicine and the National Research Council, led by committee chair Jeffrey Kahn of Johns Hopkins.

Chimpanzees not only share 98% of our genes, but they also display many of the behaviors and cognitive abilities that we once thought set us apart from the rest of the animal kingdom.  Chimps solve problems, display altruism, and feel pain and sorrow.  For this reason, the NIH came up with the following strict guidelines limiting the usage of chimpanzees in research.
  1. The knowledge gained must be necessary to advance the public’s health.
  2. There must be no other research model by which the knowledge could be obtained, and the research cannot be ethically performed on human subjects.
  3. The animals used in the proposed research must be maintained either in ethologically appropriate physical and social environments or in natural habitats.
Very few studies meet these criteria.  For example, one possibility is for the development of a vaccine against the hepatitic C virus (HCV). Only chimps and humans are susceptible to HCV, which infects 17,000 Americans per year, many of whom will require liver transplants. Even so, the committee was split on allowing that usage of chimps in HCV studies.

Laboratories already using chimpanzees will not be immediately cut off from NIH funding.  Instead, they will be encouraged to find other methods of continuing their studies. As there were only 53 chimpanzee projects funded by the NIH last year (out of more than 94,000 total study projects), it should be possible to completely eliminate the usage of research chimps within a few years.

Sunday, January 15, 2012

To evade mosquitoes, cultivate more skin bacteria

Our bodies are coated inside and out with microorganisms.  By some estimates, you are ten times as much microbe as you are you.  In fact, it’s the bacteria on our bodies that give our sweat its scent, essential for identification by dogs and for attracting mosquitoes.  But not all bacterial films are created equal. 

According to a new study by Niels Verhulst of Wageningen University and Research Centre and an international group of colleagues, people with a lower diversity of bacteria on their skin are more attractive to the Anopheles gambiae mosquito.  As this little menace is responsible for much of the malarial transmission in Africa, this finding could have implications in preventing disease.

The researchers compared the foot odor, a known A. gambiae attractant, of 48 male volunteers.  You may be relieved to read that these subjects did not have to stick their feet into a mosquito chamber.  Instead, glass beads were rubbed against their feet to collect volatiles, and then mosquitoes were allowed to approach the beads of their choice.  At the same time, the total number and the diversity of bacteria on the men’s feet were determined.

Men with more total bacteria but less diversity were more attractive to the mosquitoes. Specific genera of bacteria correlated well with attractiveness (some were liked and some disliked by the mosquitoes).  The authors speculate that this information could be used to develop mosquito traps and repellants.

For more information, Ed Yong includes a microbiology slide show on his post about this study.

Saturday, January 14, 2012

Don’t eat out of your bathroom drain

You most likely don’t make a habit of using your bathroom sink as a salad-mixing bowl.  But in case you’ve ever been tempted to snatch a contact lens out of the drain and put it back in your eye, you should know that sink drains are ripe with fungi, many of which can cause severe human infections.

Dylan Short of Pennsylvania State College and his colleagues sampled almost 500 bathroom sink drains in 131 buildings (ranging from homes to dorms to public facilities) across eight U.S. states. 82% of the buildings and 66% of the sinks harbored at least one type of Fusarium, a genus of fungus known to cause infections in humans and agricultural plants.  In fact, plumbing systems were most likely the culprit behind an outbreak of fungal eye infections among contact lens wearers six years ago.

It may not all be bad news.  Although 70% of the Fusarium species found in sink drains were associated with human disease, the other 30% may actually play some beneficial roll.  At least, that’s the optimistic view of author David Geiser.  Either way, don’t skimp on the contact lens cleaner, and don’t drop your toothbrush in the drain.

Friday, January 13, 2012

Will a satellite fall on your head?

The satellite in question is a Russian space probe called Phobos-Grunt. Designed to grab and return with a surface sample of Phobos (one of Mars’ moons), it encountered trouble soon after its initial launch on November 8, 2011.  The rocket system that would have taken it to Mars malfunctioned, leaving it stranded in a low Earth orbit.  Since then, all attempts to communicate with the probe have failed, and the entire thing is destined to plunge to Earth in the coming days.


The final architecture of the Phobos-Grunt spacecraft and its major components as of 2011. 

Unfortunately, because Phobos-Grunt was supposed to go to all the way to Mars, it retains a full payload of highly toxic rocket fuel.  The good news is that almost all of the satellite is expected to burn up in the atmosphere, including the fuel. Only a couple of dozen fragments are expected to survive reentry.

We don’t yet know exactly when or where the satellite will land, but an early estimate puts it over the Indian Ocean on Sunday afternoon. 

Thursday, January 12, 2012

First animal without a centrosome

Planarians are a favorite lab animal.  Among their talents, these cross-eyed little flatworms display an amazing ability to regenerate, even when carved into pieces.  And that’s not all that’s remarkable about these tiny creatures.  Apparently, they also lack centrosomes.

Schmidtea mediterranea

The freshwater flatworm Schmidtea mediterranea lives in southern Europe and Northern Africa is the first animal ever discovered without a crucial structure inside its cells known as the centrosome.
Image credit: UCSF/J.Azimzadeh

Here’s an abbreviated explanation of the way animal cells usually divide:  Prior to cell division, each chromosome  (DNA package) divides in two.  The centrosome, an organelle composed of two microtubule bundles called centrioles, also divides.  The two centrosomes migrate to opposite ends of the cell, each drawing a full complement of chromosomes toward that end of the cell.  Once this process is complete, the cell cleaves in two. Without centrosomes, DNA cannot be split evenly between the resulting daughter cells.

Or so we thought.  According to Juliette Azimzadeh from the University of California, San Francisco and her colleagues, the planarian Schmidtea mediterranea does not have centrosomes. The researchers discovered this odd fact when trying to see what effect eliminating centrosomes would have on the millimeter long flatworms’ ability to regenerate. Answer:  no effect at all, given that S. mediterranea never had any centrosomes to begin with. This makes planarians the only known animals to lack centrosomes.

Obviously, this changes much of what we thought we knew about cell division.  Author Sánchez Alvarado also wonders why centrosomes are found in all other types of animals, if they aren’t necessary:
There may be another function for centrosomes that is still obscured.

Wednesday, January 11, 2012

Just for fun: The next e-reader

Professor Howon Lee and his team from the Korea Advanced Institute of Science and Technology (KAIST) has developed a new e-reading system.  The new technology allows readers to skim and jump around just like they could with a paper book.

Tuesday, January 10, 2012

Wolf reintroduction for the win

In 1995, after a seventy-year absence, wolves were reintroduced into Yellowstone National Park.  How have they fared?  According to a study by William Ripple and Robert Beschta of Oregon State University, not only have the wolves thrived, but their presence has wrought a cascade of favorable changes in the park.  Wolf predation has altered both the population and behavior of elk, which in turn has allowed entire habitats to recover. 

The Gibbon wolf pack in Yellowstone.

Without wolves, elk had been allowed free reign to browse where they liked.  This resulted in the decimation of many types of bushes and trees and caused changes to the entire Yellowstone ecosystem.  In particular, critical habitats within and around streams were annihilated by the elimination of adjacent trees. Now that the elk are held in check, the plant life has rebounded.  With them has come a resurgence in a great many species, including songbirds, beaver and fish, all of whom rely on healthy streams.

It seems that reintroducing the wolves has been a win-win for almost all the species within Yellowstone.  Although the elk might dissent from this view, their numbers are still holding strong as well. 

Here’s a description by Ripple (that unfortunately cuts off abruptly at the end):

Monday, January 9, 2012

Temporal cloaking

Physicists from Cornell University have managed to create what they call a ‘temporal cloak’.  Their proof of concept demonstration shows that events can be made invisible to normal observation.  If you have a nefarious deed to hide that takes place in less than 50 picoseconds (trillionths of a second), this may be the system for you.

Briefly, the researchers took advantage of the fact that different frequencies of light (colors) move at different speeds.  The team, led by Alex Gaeta, shot a laser through a fiber optic cable.  That beam of light passed through a ‘split-time lens’, a device that increases the speed of the blue elements of the light beam and decreases the speed of the red elements.  As the light beam progressed through the cable, a gap opened up between the red and blue parts of the light. The beam then passed through a second split-time lens that reversed the effects of the first lens, stitching the light beam back together. Any event that occurred at the precise time and place of that light gap was undetectable.

Top: Experimental configuration for cloaking an event in time using two identical split time-lenses (STLs).
Bottom: The wavelength of the probe beam as a function of time.
(a)   before first STL
(b)  after the first STL;

(c)   temporal hole
(d)  before second STL
(e)   after the second STL.
When both STL's are in operation the event becomes invisible.
Used by permission.

By the way, the event you're attempting to conceal must not only occur within only a few trillionths of a second, but must be illuminated only by the beam of light you're using.  Not exactly a recipe for bank robbing.

For a much more detailed (and probably clearer) explanation, check out Skull in the Stars and a video made by Rose Eveleth.

Sunday, January 8, 2012

Cancer breath

It turns out that it’s not just onions that linger our breath.  Each time we exhale, we exude a complex mixture of volatile organic compounds (VOCs). Interestingly, these VOCs differ depending on the state of our health.  For years, doctors have been attempting to use specific VOCs to diagnose cancer.  Peter Mazzone of the Cleveland Clinic and his colleagues from that clinic, from the University of Illinois and from Florida Hospital have now used that technique to not only identify cancer patients but to discriminate between types of cancer. 

For their study, the researchers used a colorimetric sensor array.  This device, designed by the Metabolomx company, is calibrated to determine the concentration of VOCs in a person’s breath. Encouragingly, the colorimetric test accurately picked out the lung cancer patients over 80% of the time.  Of the people who tested positive for cancer, the test was also about 80% accurate in discriminating between different types and stages of cancer.

This study only involved 229 people, but more experiments are being done.  Obviously, doctors cannot yet rely on a breath test over other methods of diagnosis.  However, analysis of VOCs may one day be used in conjunction with other tests, or as an initial screening tool.

Saturday, January 7, 2012

Two reasons neutrinos can’t go faster than light

A few months ago, I posted an article about faster-than-light (FTL) travel.  While that data has yet to be refuted, most physicists are certain that it soon will be.  Here are just two reasons why FTL travel is impossible, even for neutrinos.

First, let's take an extremely simplified look at how those speedy neutrinos were created.  Physicists produced subatomic particles called ‘pions’.  The pions were sent down a long tunnel, along the way decaying into neutrinos and other particles. Those neutrinos, being able to pass through solid objects, continued their merry way through the Earth to Gran Sasso, Italy, where they were clocked at superluminal speeds. 

Here’s the problem:  To have the energy required to travel that fast, the neutrinos had to inherit that energy from the pions from whence they came.  But if those pions had had that kind of energy in the first place, they’d have lasted longer, which means they would have spent more of their energy before decaying into neutrinos.  In other words, you just can’t get parent pions to decay into neutrinos that retain enough energy for FTL travel.

The supernova problem:

In 1987, we observed a supernova  (SN1987A) that showered the Earth with both neutrinos and light from 160,000 light years away.  If those neutrinos had traveled at the same speed as the FTL neutrinos in the CERN experiment, they would have arrived four years before we saw the explosion.  Needless to say, this did not happen. 

So those are just two reasons why there must be some error in the FTL conclusion.  By the way, even scientists who adamantly deny that FTL travel is possible think the physicists at CERN did the right thing by publishing.  At the least, we will probably gain some new understanding about subatomic particles.