Science-- there's something for everyone

Saturday, July 31, 2010

Most massive star discovered

Paul Crowther of the University of Sheffield and his team of astronomers used the Very Large Telescope in Chile plus data from the Hubble Space Telescope to discover the most massive star found to date. The star, designated R136a1, is in the R136 star cluster. That’s in the Tarantula nebula within the Large Magellanic Cloud, for those of you getting out your star maps.

Image shows relative sizes of young stars, from 'red dwarfs,' through low mass 'yellow dwarfs' such as the Sun, to massive 'blue dwarf' stars, as well as the 300 solar mass star named R136a1.

Credit ESO/P. Crowther/C.J. Evans

At an estimated 265 solar masses, R136a1 is the first star larger than 150 solar masses to have been found. Just to state the obvious, our sun is exactly one solar mass in size. This new behemoth is thus about 265 times as massive as our sun. And that’s just its mass now. Astronomers suspect that it was over 300 solar masses when it was ‘born’, but that its extremely high temperature (over 40,000 degrees) and powerful winds have steadily stripped away its mass.

I should point out that mass and size are two different measurements. The largest known star is VY Canis Majoris with a diameter about 2000 times that of our sun. However, it’s only about 20 solar masses. In other words, it’s a gigantic puffball of a star. In contrast, at 35 times the sun’s diameter, but close to 300 times the sun’s mass, R136a1 is more like a lead weight.

Like all exceptionally bright, massive stars, R136a1 is expected to blow through its life cycle relatively quickly. Unlike stars that are less than 150 solar masses, when it does go, astronomers expect R136a1 to completely blow apart, leaving no black hole or remnant behind.

There is a slight possibility that R136a1 is not a single star, but rather a binary star. However, even if that were the case, it’s likely that one of the stars in the pair would still be a record holder.

Friday, July 30, 2010

Just for fun: Animal embroidery

My friend Melinda Muscato makes and sells incredible embroidery. Here are a few examples of her work. You can see more here, here and here:

Yellow, Red and Maroon Serpent Embroidery

Thursday, July 29, 2010

Dieting success determined by genetics

Karen Reed of North Carolina State University and her colleagues from NCSU, the University of Toronto, the University of Queensland, and the Georgia Institute of Technology have proven what we’ve all suspected: diets do not work equally well for everyone. OK, at least not for all fruit flies.

Reed and her associates started with 146 distinct genetic lines of Drosophila melanogaster (fruit flies). The flies were given four types of diet: nutritionally balanced, low calorie, high sugar, and high fat. The flies were then carefully observed, and metabolic traits and weight were measured. At the end of the study, the researchers found that different diets given to genetically identical flies only altered weight and metabolism by an average of 1-2%. In contrast, genetically distinct flies differed in weight gain by up to 23%. In other words, the genetic makeup of the flies played a much larger part in determining whether they gained weight than did even high fat or high sugar diets.

The obvious conclusion, if this data translates to humans, is that one-size-fits-all diet plans are likely to be ineffective for many people. Eventually, people may have their genomes analyzed and specific diet plans tailored for them.

Wednesday, July 28, 2010

Longest untethered robot walk

Andy Ruina of Cornell University and his engineering students have set an unofficial record for the longest continuous untethered walk (operated solely by remote control) by a robot. The robot, named ‘Ranger’, took over a hundred trips around an indoor track at Cornell, completing a 14.3 mile walk before succumbing to low battery power. To put that in perspective, as of July, 2010, the two Mars rovers had traveled just under 14 and just under 5 miles, respectively. And that took them seven years.

Ranger set an Earthly record two years ago by walking 5.6 miles, which was subsequently beaten by the ‘BigDog’ robot from Boston Dynamics. This year, Cornell students and Ranger retook the record.

Ruina hopes that his work in walking robots will help not only engineers as they create robots for a variety of purposes, but also the designers of prosthetics for human amputees.

Here’s a clip of Ranger making its historic walk:

If you think that’s wild, check out BigDog:

Tuesday, July 27, 2010

Mouse cages matter

Sometimes, researchers using genetically identical mice will get different results from their experiments. Diego Restrepo and his team from the University of Colorado may have figured out why. It seems that different types of cages can yield different results.

The mouse cages used in laboratories differ in a number of ways. For example, in some cases, airflow is passively filtered, whereas in others, fresh air is mechanically blown through the cages. The latter cages are called ‘high-ventilation’ cages. There were significantly more mouse fights in the high ventilation cages, possibly due to differences in olfactory cues or temperature.

The scientists encourage other researchers to pay attention to the type of cage used from now on, in order to ensure consistent results.

Monday, July 26, 2010

Halting a deadly parasite

Luciana Madeira da Silva and Stephen M. Beverley from the Washington University School of Medicine in St. Louis Missouri have discovered the Achilles’ heel of a deadly parasite. The parasite appears to be susceptible to a class of drugs that are already used to prevent organ rejection.

The parasite in question is called Leishmania, and is responsible for more misery than any other parasite on the planet, except for the one that causes malaria. As many as twelve million people worldwide are infected with Leishmania, with symptoms ranging from skin lesions and fever to death.

The Leishmania genome was found to contain three versions of a particular type of enzyme called a TOR kinase. Humans and other mammals have one version, mTOR. I wrote about this enzyme in conjunction with autism, but it is also essential for cell survival. Leishmania need all three mTOR genes in order to survive and infect humans.

In humans, the drug rapamycin is known to inhibit mTOR (which is why mTOR stands for ‘mammalian target of rapamycin’). Rapamycin is used as an immunosuppressant drug after organ transplantation. It’s also being tested as a cancer treatment. Now scientists plan to test it against Leishmania. If it doesn’t work, there are other drugs that might.

As Beverly optimistically states:

Given the numerous inhibitors already available, I think there's a pretty good chance that we'll be able to identify a compound that specifically inhibits one of Leishmania's TOR kinases.

Sunday, July 25, 2010

Protons get a wee bit smaller

New measurements show that the charge radius of a proton is not 0.8768 femtometers, as previously thought, but is instead only 0.8418 femtometers. As I'm sure you all know, a femtometer is one quadrillionth of a meter, or 10-15 of a meter. To get an idea of how small this is, click on the graphic in this previous ‘Just for fun’ post. Randolf Pohl of the Max Planck Institute led an international team of physicists in revising the proton measurement.

Getting the new, more accurate measurement involved several months of preparation and data collection. Without going into too much detail, they replaced the sole electron in a hydrogen atom with the much larger muon, and then used a laser to excite the muon into a more energetic sphere. The energy difference between the two orbitals correlates directly with the size of the nucleus.

Obviously, the measurements involved were incredibly small. To give you an idea of the precision required, the physicists had to create a laser that could fire in only 900 billionths of a second in order to get the results they needed.

If this data is confirmed, it means that some of the predictions of quantum electrodynamics will need to be recalculated. This could send repercussions throughout the physics community.

Saturday, July 24, 2010

Cancer cells killed by healthy cells

Yasuyuki Fujita of University College London and Yoichiro Tamori of Florida State University led an international team in discovering a process by which normal cells can kill off carcinoma cells.

Carcinomas originate in the layer of cells called the
ephithelium. These cells make up the lungs and various glands as well as parts of the digestive tract. In the earliest stages of tumorigenesis, one or a few cancerous cells find themselves surrounded by normal, healthy cells. Sometimes those healthy cells are capable of killing the tumor cells, but in other cases, the cancer cells manage to evade them and replicate themselves. It seems that the healthy cells compete with the cancerous cells in some way. What allows them to do this? That was the question the team of scientists set out to answer.

Flies and mammals are both known to have a tumor suppressor gene called Lgl (which stands for lethal giant larvae—hey it was discovered in flies first). When functional, Lgl prevents cells from becoming cancerous. It was also known that Lgl worked in association with one or more hitherto unknown proteins. The team of scientists
managed to trap Lgl’s binding partner, and discovered that it was a single protein subsequently named ‘Mahjong’.

Next, the researchers tested fly cells that were missing the Mahjong gene. When surrounded by normal cells, the Mahjong minus cells died, but when surrounded by other Mahjong minus cells, they didn’t die. They repeated this test with canine kidney cells and saw the same result. In other words, the Mahjong mutants were losing the competition with the normal cells. Over-expressing Mahjong also rescued Lgl mutants from dying, though the reverse was not true.

The scientists hope that this new information will help them give normal cells a competitive edge over tumor cells in the earliest stages of tumorigenesis.

Friday, July 23, 2010

Far fewer dinosaur species than previously suspected

Since their earliest discovery, dinosaurs have been divided into different species based on various morphological differences. Evidence is now mounting that many of these differences represent different life cycle stages within one species, rather than different species. That idea was first presented by Jack Horner of Montana State University’s Museum of the Rockies.

Horner previously established this concept with respect to the dinosaur Pachycephalosaurus. Now, he and his student John Scannella have extended that idea to Triceratops and Torosaurus. Previously, these were thought to be distinct species. However, Horner and Scannella have shown that Torosaurus is in fact the most mature stage of the Triceratops life cycle.

The paleontologists spent the last decade collecting and examining hundreds of fossils at the Hell Creek Formation in eastern Montana. Among the finds were Triceratops skulls of various sizes. The few Torosaurus skulls, in contrast, were all of adults. Upon closer inspection, the Triceratops fossils showed signs of growth and change consistent with juvenile life stages. Other so-called Ceratopsid species may also turn out to be life cycle stages of the same species.

Horner believes there may actually have been one third fewer dinosaur species than previously thought, especially toward the end of their reign. This may have been one reason the dinosaurs did not survive the impact of the meteor that ended the Cretaceous period; as a group they were not genetically diverse enough to withstand the decimation.

Thursday, July 22, 2010

Just for fun: Fractal edition

Here are a couple of fractal videos to keep you busy:

The first, by youtuber zettix1 is unfortunately a bit blurry, especially at the end, but the 3D effects are very cool.

If you prefer your Mandelbrots set to music, here's a sample by youtuber gooozz.

Now don't get hypnotized!

Wednesday, July 21, 2010

Dissolvable microneedles

Vaccinating by injection offers a dangerous temptation to drug users in the form of leftover needles, or ‘sharps’. Scientists from Emory University and the Georgia Institute of Technology may have solved this problem by inventing dissolving microneedle patches. The technique was successfully tested with influenza vaccine in mice.
To make the vaccines, freeze-dried influenza vaccine was mixed with a biocompatible polymer and then solidified into microneedles by using ultraviolet light. The tiny needles are each only 650 microns long and arranged in arrays of 100.

A dissolving microneedle patch compared to a US nickel.
Credit: Credit: Sean Sullivan, Georgia Tech

When placed on the skin, the microneedles penetrate only the outer layers of the skin where they promptly dissolve, leaving the vaccine in the skin. This is actually a very effective way to administer vaccines. In tests on mice, the new micro array performed as well or better than injected vaccines.
More studies must be done before this new vaccination method is accepted for public use. If the new technique does pass safety and efficacy tests, it could prove to be an excellent alternative. The scientists involved envision letting people pick up their vaccine patches at a pharmacy and administering them by themselves at home. Because the vaccine is used in dry form, longterm storage would be possible. And of course, there would be a complete lack of all ‘sharps’.
This microscope image shows dissolving microneedles encapsulating a pink dye used to simulate how a vaccine would be incorporated into the needles.
Credit: Credit: Sean Sullivan, Georgia Tech

Tuesday, July 20, 2010

Looking for something? Try a verbal cue.

Gary Lupyan of the University of Pennsylvania and Michael Spivey from the University of California Merced discovered that verbal but not visual cues can improve someone's ability to find what she's looking for.

The cognitive psychologists put 80 volunteers through a series of tests. In each case, the participants were asked to identify whether they saw a particular letter when images were flashed on a screen at speeds that should have rendered them invisible. In one set of experiments, either a visual (picture of the letter to be found) or auditory (recorded letter name) cue was supplied prior to flashing either the letter or a random image. The volunteers were asked whether or not they had seen the letter in question. In some trials, the position of the flashed letter was randomly moved around the screen.

The volunteers had much greater success in correctly identifying whether a target letter was present or absent following an auditory cue. No such benefit was gained by having seen a visual representation of the letter to be sought.

I’m going to put this into practice the next time I lose something. Instead of silently blundering about, I’ll try announcing ‘keys!’ and see if that helps.

Monday, July 19, 2010

New variation on transit time method of finding exoplanets

One way to find extrasolar planets is to look for the slight dimming that occurs when such a planet crosses the path of its star. This method is known as ‘the transit method’. The planets found by this method have tended to be extremely large. Not the type of planet on which one would expect to find life. Now, an international group of astronomers led by Gracjan Maciejewski of Jena University in Germany, have used a variation of the transit method to find Earth-sized planets.

The new technique is called the Transit Timing Variation, or TTV. So far the team has used it to detect a new planet in the star system called WASP-3. That system contains a previously discovered planet known as WASP-3b, a gas giant with 630 times the mass of the Earth. With TTV, the astronomers carefully measure slight deviations in the transit time of WASP-3b across its star. Those tiny deviations are caused by another, much smaller planet, which is exerting a pull on WASP-3b. The new planet, with about 15 times the mass of the Earth, was duly dubbed WASP-3c.

This is the first time this method has been used. WASP-3c is one of the smallest exoplanets found to date, leading astronomers to hope that TTV can be used to find even smaller and thus more Earth-like planets.

Sunday, July 18, 2010

Serendipity results in new type of tape

Every once in a while, a new discovery is made by accident (think Teflon). Researchers from Oregon State University may have added to that tradition. They set out to create an adhesive made from wood that would melt at high temperatures, but instead created a new vegetable oil-based pressure-sensitive adhesive.

Hot-melt adhesives are commonly used in glue guns. The adhesive is solid at room temperature, but liquid and sticky when heated. Unlike other types of adhesive, no chemicals are required to cure the glue.

In contrast, pressure-sensitive adhesives do not require heat or any chemical curing process. Instead, the glue adheres to a surface because of light pressure applied to it. Although they can be permanent, often pressure-sensitive adhesives are used for removable items, like sticky notes.

Kaichang Li and his team were attempting to make a hot-melt composite adhesive out of wood and vegetable oils. Although that attempt failed, the team noticed that they had created a very sticky resin which proved perfect for gluing together sheets of paper.

As Li’s commented:

This adhesive is incredibly simple to make, doesn't use any organic solvents or toxic chemicals, and is based on vegetable oils that would be completely renewable, not petrochemicals. It should be about half the cost of existing technologies and appears to work just as well.

The new adhesive is expected to be useful for everything from duct tape to postage stamps.

Saturday, July 17, 2010

Reversible watermarks

Watermarks are images or patterns printed onto paper that serve both to authenticate documents and to prevent the forging or reusing of those pictures or documents. They can be subtle or obvious, depending on the purpose of the watermark. What they haven’t been, up until now, is reversible. Govindarajan Yamuna and Dakshinamurthi Sivakumar of Annamalai University in India have solved that problem.

Briefly, the designers convert every pixel in a picture into a code they term a Hash Message Authentication Code (HMAC). This code can be used both to embed watermarks at specific pixels and to restore the original image. The two images (with and without watermarks) can be compared to ensure authenticity.

Why is this important? Some photographs, particularly those with military or legal relevance must be authenticated to ensure that the images haven’t been altered in any way. Digital signatures and watermarks are a way to do this. However, part of the digital data is usually destroyed by the placement of the watermark. Reversible watermarks can certify the authenticity of a photograph without corrupting the original data.

Friday, July 16, 2010

Cat mimics monkey

Yes, you read that right. In a study that began in 2005, researchers from the Wildlife Conservation Society (WCS) and UFAM (Federal University of Amazonas) have documented a case of a feline mimicking a primate.

The feline in question was a margay (top right), a small spotted wild cat indigenous to Central and South America. One of its main food sources is a small primate called a pied tamarin (top left). Margays weigh up to eight pounds, whereas the tiny tamarins weigh less than a pound.

The team of researchers observed a margay making calls similar to those emitted by baby tamarins. The calls were so persuasive that the adult tamarins were enticed to investigate. Fortunately for the monkeys, the ruse did not work. The tamarins realized they were being duped in time to escape. However, the very fact that the wildcat used a mimicking strategy was fascinating.

Apparently, there have been reports of jaguars and pumas copying the sounds of their prey, including primates and agoutis. Until now, this sort of behavior had not been confirmed.

Thursday, July 15, 2010

Just for fun: Animal Infrared

Cool Cosmos team at Caltech has created an infrared zoo. Images were taken by Linda Hermans-Killam at Moorpark College, The Santa Barbara Zoo, Animal House (The Oaks), and the Tierra Rejada Family Farm.

Here's a leopard gecko (a 'cold-blooded' reptile):

Wednesday, July 14, 2010

Solving Barcelona’s parking problems

José López Vicario and Antoni Morell led a research team from the Universitat Autonoma de Barcelona’s School of Engineering in developing a novel parking system. They call the system XALOC (Xarxes de sensors per a la gestió d'Aparcaments públics i LOCalització).

The system involves a couple of components. First, each parking space is equipped with a sensor on the ground. This sensor detects whether or not the space is occupied, and sends that information to a central station via the internet. The central station then transmits that information both to indication panels in the street and to navigation transponders carried in participant’s vehicles. Thus, drivers can proceed directly to empty parking spaces rather than spending time driving around looking for places to park.

The system uses a new position and location technology with greater precision than standard GPS systems. The developers hope this new system will greatly improve traffic management and circulation. I certainly hope it will come to my area. I was impressed when the new parking structure at my local mall started indicating how many spots were available on each floor, but this is even better.

Tuesday, July 13, 2010

Jumping genes really move around

Jumping genes, more formally known as ‘transposons’ (short for transposable elements) are segments of DNA that can replicate and reinsert themselves into new locations on the genome. The most common type are ‘retrotransposons’, which go through an RNA intermediate in order to move around. It turns out that these genetic elements are much more active than was previously thought.

Before I continue, I want to be clear about what’s going on. When a transposon ‘jumps’ to a new location, the original piece of DNA is not removed from its location in the genome. That piece is replicated, either directly or through an RNA intermediate, so that there are now two transposons, one left in the original spot, and the second, new piece that is free to insert itself into a new location. The insertion site is chosen at random. If the new transposon inserts itself into the middle of an essential gene, the results can be devastating. Alternatively, the insertion may be completely benign. In either case, the genome now has one more copy of the transposon than it did before.

It had been thought that this sort of event occurred about once in every 20 births. Not so. Scott Devine, currently at the University of Maryland, and his team from the University of Maryland, and from Emory University, where the work was initiated, have found that LINE-1 (L1) and Alu retrotransposons are so active that virtually every newborn has one in a new location. In addition, transposons are very likely to move to new locations during tumor formation. Six out of 20 lung tumors had transposon insertions in new locations compared to adjacent normal tissues.

Taken together, these data indicate that the movement of retrotransposons may be a major factor in both human evolution and in disease.

Monday, July 12, 2010

Beeglue can fight MRSA

Balls of propolis

First, let’s define a few terms. MRSA stands for multidrug-resistant Staphylococcus aureus (or sometimes methicillin-resistant). These bacteria are a huge problem in hospitals, because, as the name implies, they are almost untreatable. Some strains of MRSA are resistant to all known antibiotics. Beeglue, also known as propolis, is a natural antiseptic sealant used by bees to repair small gaps in their hives. To be clear, it is not beeswax or honey. It's made from the sticky resins and sap that bees collect from nearby plants.

Véronique Seidel and her team from the University of Strathclyde, Glasgow, screened fractions of propolis acquired from the Solomon islands against MRSA. They found two compounds within the propolis, which they called propolin C and D, which appear to be effective in defeating MRSA. The researchers hope these propolis extracts can serve as templates for manufacturing anti-MRSA agents. This would be welcome news, as the CDC reported over 18,000 MRSA deaths in 2005 alone.

Sunday, July 11, 2010

New and improved peak heart rate calculator for women

Remember that formula for calculating your peak heart rate? 220 minus your age? That formula has been in use for almost four decades by doctors to determine fitness levels and by athletes to get a proper workout. Well, according to new research by Martha Gulati of Northwestern University and colleagues from Northwestern, Emory University, University of Chicago, New York University and Cedars-Sinai Heart Institute, that formula only applies to men.

The researchers looked at data from over 5000 healthy women who had participated in the Chicago based ‘St. James Women Take Heart Project’ back in 1992. The subjects, all over 34 year-old, had undergone extensive stress testing. The scientists then compared mortality rates over the next 18 years with the heart rate tests.

They discovered that the women’s peak heart required an entirely different formula, namely, 206 minus 88% of age. For people between age 30 and 75, this translates to 5 to 10 fewer heart beats per minute for women than for men. By using the old formula, a doctor might have encouraged women to exercise well past their true peak heart rates.

Unlike the men’s formula, the women’s formula is not something everyone can calculate in their heads. Luckily, the calculation only has to be done once each year, if you can remember your result. Good news for those who can’t: Gelati says she’s working on an iPhone app. to do the calculation for you.

Saturday, July 10, 2010

Using magnetic levitation to analyze food

Magnetic levitation (maglev) is best known for use in high speed trains. George Whitesides and his team from Harvard University have discovered a new use for the technique. They use it to analyze the fat and salt content of a variety of foods.

Abstract Image

The scientists built a special device to analyze food and water samples. The sensor consists of two magnets on top of each other with like poles facing each other. A container filled with a paramagnetic fluid (that is, a fluid that is attracted to external magnets, but is not inherently magnetic) is placed between the poles with a droplet of the substance to be tested suspended within it. The density of the substance, which directly relates to its fat and/or salt content, determines where the droplet will float once the maglev device is switched on.

The device has successfully been used to compare the fat content of different types of milk or vegetable oils, cheeses or peanut butter samples, and to estimate the salinity of different water samples.

Diagram credit: Charles Mace and Kat Mirica.

Friday, July 9, 2010

Rats have a sense of direction soon after birth

Scientists from University College London have determined that a rat’s sense of direction is innate, and develops before the animal begins to explore its environment.

Thus far, three types of spatial neurons have been found in rat brains, all in the hippocampus. In humans, this part of the brain is critical for long-term memory storage as well as spatial orientation. Although the neurons continue to develop after the baby rats move out of their nests, they initially fire well before such exploration begins. This indicates that the ability to orient must be innate.

Personally, I take exception to this conclusion. But then again, results from model organisms don't always translate to humans.

One week old rat pictured with quarter by Mark Blumberg, April 19, 2005.