Science at Atheist Universe
VIDEO OF THE WEEK: A surgical robot peels a grape. A Da Vinci surgical robot was on show at an open event to raise awareness of men's cancers for Blue September at Southmead Hospital on September 28 2011. Members of the public, former patients, prospective patients, staff and GPs all attended the event to try their hand at robotic surgery. Here, urology fellow Ramesh Thurairaja peels a grape. The video is amazing, the robot is so precise. For the men in the group, just try not to think about the robot doing this to your prostate when you watch the video.
ASTROPHYSICS: Galaxy Clusters Validate Einstein's Theory. One of the predictions of general relativity is that light will lose energy as it escapes a gravitational field. Thus, light coming from the core of a galaxy should lose more energy than light coming from outer regions. This is called gravitational redshifting. But this effect has proven difficult to measure in individual galaxy clusters because it is small and also because of interference from redshifting coming from other causes (such as the expansion of the universe or the orbital velocity of galaxies. A Danish team of astrophysicists came up with a great idea: they used the redshifting measuring from many, many galaxy clusters (~8000 galaxy clusters) instead of individual ones. They determined that, as predicted by Einstein's theory, the redshift was proportional to the distance from the center of the galaxy. In addition, the results support the Lambda-Cold Dark Matter model of the universe and lends support for the existence of dark energy. The findings appeared in Nature this week.
NEUROSCIENCE: two interesting posts this week!
Scientists Can Now Reconstruct What You See With fMRI. The video is absolutely astonishing. The work is basically computational modeling of the visual system, aimed at describing how the brain encodes visual information. The computer model should predict the brain’s responses during natural vision. The technique used is functional magnetic resonance imaging (fMRI), because it provides non-invasive measurements of brain activity. Basically, subjects watched several hours of movie clips while they were in the MRI machine. Their brain activity was recorded, and matched with the video clips which are deconvoluted as motion, edges, and shapes. A “dictionary” is then built based on the translation of the edges, shapes and movements and the corresponding recorded brain activity. The validity of the dictionary is tested with new movie clips, to see if the model holds. Ultimately, they downloaded random clips from YouTube and used the dictionary to predict brain activity. The video above is an average of the 100 clips where the concordance between the video and predicted brain activity was most similar to observed brain activity. Very impressive.
What "teleported" rats tell us about how memory works. Do you know the feeling of temporary disorientation when you exit the elevator at the wrong floor in your office building or at home? It happens because your brain was counting on a certain map of the place, and the feedback clashed with that map. Neuroscientists tricked rats into thinking they had been "teleported" by suddenly altering the lighting pattern of plexiglass boxes (one with white light, another with green light), where they were used to search for cookies. In other words, if the rat was in the white light box searching for the cookie, and they switched the light to green light as in another box where the rat had also learned to search for cookies, the animal became temporarily disoriented but eventually found the cookie. When they recorded the brain waves from the rat's hippocampus, which is the brain's memory center, they saw that the rat sets off searching for a cookie with a given pattern of theta waves, and that at the moment of "teleportation," one group of neurons kept firing with the "original" pattern, while another group of cells fired with the pattern corresponding to the green box. But within 125 milliseconds, they were all firing together. Theta waves are produced by "place cells", which record both the surroundings and the animal's movement within the environment, and they are known to fire in cycles of 125 milliseconds. The novel finding is that the two distinct wave patterns overlapped until one won over the other, suggesting that memories are recorded in neat 125 millisecond packages and that this prevents the mixing-up of different memories.
BOTANY/EVOLUTION: Miracle berry turns sour into sweet. Ed Yong always finds the most interesting stuff for his blog. I had never heard of this fruit. Called the "miracle berry" (Richadella dulcifica), when eaten in conjunction with something sour, it turns the sour taste into unbelievable sweetness! If you eat one of these, you can drink lemon juice or vinegar straight up and taste only sweetness! The fruit was traditionally consumed by people in West Africa with their meals to mask the acidity in their foods. The protein responsible for this miraculous effect is called, aptly, miraculin. Scientists originally thought that miraculin works by changing the shape of the receptors for sweetness in our mouths, making them respond to sour taste as well, which is then perceived as sweet. The actual story, just published in PNAS, is even more interesting. Miraculin does indeed bind to the sweet receptors, actually strongly enough to outcompete sugars, under neutral conditions. But under acidic conditions, miraculin changes confirmation, causing a conformational change in the sweet receptors, making them fire like crazy. The scientists also describe another sour-to-sweet changing protein,called neoculin, from the Malaysia lumbah plant. Neoculin also binds to the sweet taste receoptors, but to a different part of the receptor than miraculin, and unlike miraculin, neoculin tastes sweet on its own, no need to change the acidity, and it is even more effective in changing a sour taste to a surreal sweet taste. In addition, miraculin and neoculin are completely unrelated, evolutionarily speaking, different amino acid sequence, etc., so this is a case of splendid convergent evolution.
PALEONTOLOGY: Prehistoric Colors Preserved in Near-Perfect Beetle Fossils. This is absolutely amazing. Color has been preserved in fossil beetles up to 40 million years old! The picture is of a 40 million year old fossil beetle found in Germany. Although these fossils are not as famous as the colored plumage of fossil dinosaurs, these represent the best preservation of fossil color available. This is because the beetle's colors are not produced by pigments (as is the case with feathers) but they are structural colors, produced by the interaction of light with the surface of nanometer-sized geometrical structures in the epicuticle (outer layer of the skin). This means that subcellular structures have actually been preserved during fossilization. To investigate if the colors are faithful, scientists compared the surface shape of the fossils with those of modern, live beetles. The conclusion is that the preservation is not perfect, and that to imagine the colors as they were 40 million years ago, we need to mentally redshift the colors a bit, for example, the blue beetle in the photo may have been more greenish, and green fossil beetles may have been a little more yellowish. Click on the link to see many photos from these spectacular fossil insects.
LAST, BUT NOT LEAST: Category: “Evolutionary psychology nonsense”: An evolutionary psychology explanation for domestic violence?. Here we go again...Another "caveman" theory, another completely untested and unverified, and not even very logical explanation for domestic violence, based on "evolutionary biology" and some really, really flimsy data. Here it goes: domestic violence exists because men find it a good strategy to ensure his children are actually his and his wife/partner is not cheating on him. If your jaw dropped, wait until you read how they came up with this "wonderful" explanation..
Science bits and news from other sites:
Why does the garlic trick work? First off, I had never heard of this simple trick to peel garlic. Watch the video, and take notes. Wow! I’m going to try it tonight. Report back if you’ve tried it and it worked.
But why? Why does it work? How does it work? This is a science question. John Rennie from the PLoS blog “The Gleaming retort” carries out an experiment, and comes up with a reasonable explanation. When he put a single unpeeled clove into the metal bowls, nothing happened. But do it with 2 cloves, and it worked! He thinks that more than one unpeeled clove necessary because friction and mutual abrasion is crucial. It’s the same principle as a rock tumbler, in which the stones rub one another to smoothness. Physics, baby. It works.
Twitter-Mining Captures Global Mood Patterns. A scientific analysis of tweets! Cool. Scientists looked at half a billion tweets from across the world and quantitated the number of positive vs. negative words in the tweets, according to time of the day and day of the week. The social scientists used Linguistic Inquiry and Word Count, a text analysis program that quantifies the emotional content of statements, and analyzed a total of 509 million tweets over 2 years by 2.4 million people in 84 countries. The results show that good feelings peaked in the morning (although I know my fair share of moody not-morning people), dipped during work hours and then raised again in the evening. Apparently negativity is cumulative, negative feelings increased with the day of the week until they disappeared Friday night. Not too surprising. But believe it or not, before taking this innovative approach, moods were hard to measure and quantitate in such a global scale. It has long been suspected that mood is governed by circadian and sleep cycles, this is pretty much accepted, but studies of mood fluctuations have so far been discordant as to times of the day, etc, due to discrepancies in the methodologies used by the different studies. This huge Twitter study eliminates all those differences. Of course, Twitter users do not represent the whole of humanity either, but it is nevertheless a fantastic opportunity for social scientists. A caveat is that the 140-character format itself might also be misleading, because it eliminates nuances in emotional states. And of course, it doesn’t answer these fundamental questions, why do these daily patterns exist? And how can we harness this knowledge to improve human lives and happiness levels? Here is the link for the abstract of this study that was published in Science.
Mercury’s Explosive Volcanic History Revealed. Do not miss the many great photos from NASA’s MESSENGER spacecraft. Though only halfway through its first year in orbit around Mercury, the spacecraft has already revealed that the planet had a pretty violently volcanic past. Tiny Mercury is the densest of all the planets in the solar system, composed of ~60% iron (2X the iron content of our blue planet). MESSENGER has revealed that the craters are mostly the result of volcanism and not impacts with asteroids. Some of the images revealed that the long channels and hills seen on Mercury were likely formed by huge lava flows. Volcanic vents can clearly be seen too.
Rat cyborg gets digital cerebellum. One of the main functions of the cerebellum is to coordinate movements. It has a relatively simply neuronal architecture so it s a well suited brain part to try to imitate artificially by a computer chip. Scientists at Tel Aviv University just did this: they built an artificial cerebellum that they wired into brain-damaged rats and restored some motor function. This is significantly different from cochlear implants or prosthetic limbs, because these communicate with the nervous system in only one direction. The artificial cerebellum receives signals from the body as to its position, interprets it, and responds with a signal to a different region of the brain. To build the artificial cerebellum, the scientists first analyzed brainstem signals feeding into a real cerebellum and the output that the cerebellum generated in response. They used this information to generate a synthetic cerebellum, which is basically a computer chip that sits outside the rat’s head and is wired into the brain via electrodes. They tested the artificial cerebellum by teaching rats to blink in response to an auditory signal, using Pavlovian association methods (puff or air to the eye, together with a sound). Brain-damaged rats never learn the motor reflex, while rats with the artificial cerebellum did. Although the function restored is very basic, it is an important first step towards creating chips capable of restoring more complex functions. The next step is to build chips that mimic more complex cerebellar functions such as sequences of movements. The scientists think it will likely take several decades, but that specific, well-organized brain parts such as the hippocampus or the visual cortex will have synthetic counterparts before the end of the 21st century.
New Life-Forms Found at Bottom of Dead Sea. Dead Sea diving is not for everyone: divers must carry 90 pounds of weight to lower his or her buoyancy, and also wear full face masks to protect their eyes and mouths from the extremely high salinity, that can cause blindness and even death. In spite of these challenges, scientists-divers are studying dozens of giant craters spewing fresh water and brimming with bacteria. The Dead Sea is otherwise barren from any life. But it isn’t truly dead: the craters are covered with bacterial films and sometimes surprisingly thick mats. These bacteria are all new species. This discovery changes how the Dead Sea is seen from a biological perspective because it shows that life diversity can thrive in the most unexpected places. The bacteria in these green biofilms on the surface of the craters use both sunlight and sulfide, naturally occurring in the freshwater springs, to thrive. At the bottom of the crater live bacteria that live exclusively on sulfide, and they form a white biofilm.
Dodo bird was a resilient island survivor before the arrival of humans. The poor dodo (Raphus cucullatus) became the symbol of everything that is stupid or obsolete and was meant for extinction. But this flightless relative of the pigeon that inhabited the island of Mauritius was in reality not stupid or clumsy, but a resilient survivor. Its large size and inability to fly were adaptations that allowed this bird to survive some of the most hostile conditions such as extreme drought and volcanic eruptions. We turned out to be a much more destructive force than extreme conditions, unfortunately for the dodo. The new insight into the dodo’s life was a discovery of fossil bones from ~0.5 million animals at the island of Mauritius, representing a 4000 year old catastrophic event. Oxygen isotope analysis of geologic features on Mauritius and nearby islands, revealed that the animals died during an extreme drought that lasted several decades. The bones were found all in one location. But none of the species found in this common dry grave went extinct, they all bounced back, including the dodo. The bird was perfectly adapted to the island’s habitat, there were no predators so he had no need to flee. When he met men and their rapacity, the dodo was not equipped to deal with predation, and it went extinct. The island’s giant tortoises also survived the drought but also went extinct when humans arrived on the island. Today, Mauritius environment is so degraded from human exploitation, that scientists think that should another drought like the one that occurred 4,000 years ago were to happen, none of the native species will make it, no plants, no animals.
Oil Spill Affected Gulf Fish’s Cell Function, Study Finds. The consequences of the BP oil spill in the Gulf of Mexico are starting to appear. A minnowlike fish, the killifish, that is a major source of food in wetland marshes, is showing alterations in cellular function such as poorly regulated estrogen levels, that are indicative of potential problems in their reproductive ability. The report is the first to show biological effects on wildlife since the spill. These findings are alarming, because similar effects on fish, birds, and sea otters were seen after the Exxon Valdez spill in Alaska, and these were predictive of population declines and even population collapses. In addition, work in progress suggests that fish embryos that were exposed to sediment contaminated by the oil spill developed abnormally.