Science Sunday #8
Posted by Don McLenaghen on August 7, 2011
– and on the seventh day we learn.
Each week I hope to give a synopsis of the interesting science stories I have heard on my plethora of science podcasts I listen to each week plus anything I pick up scanning the inter-web. This week’s top stories:
Words of the Week:
Fusioneer – One of the growing number of armatures who have attempted (38 or so having achieved) nuclear fusion reactions at home.
PET Scan – Positron emission tomography is a nuclear medicine imaging technique that produces a three-dimensional image or picture of functional processes in the body. The system detects pairs of gamma rays emitted indirectly by a positron-emitting radionuclide (tracer), which is introduced into the body on a biologically active molecule. Three-dimensional images of tracer concentration within the body are then constructed by computer analysis.
MRI Scan – Magnetic resonance imaging (MRI) (AKA: nuclear magnetic resonance imaging-NMRI, or magnetic resonance tomography-MRT) uses a powerful magnetic field to align the magnetization of some atoms in the body, and radio frequency fields to systematically alter the alignment of this magnetization. This causes the nuclei to produce a rotating magnetic field detectable by the scanner—and this information is recorded to construct an image of the scanned area of the body. Strong magnetic field gradients cause nuclei at different locations to rotate at different speeds. 3-D spatial information can be obtained by providing gradients in each direction. MRI provides good contrast between the different soft tissues of the body
Colon Cleansing Has No Benefit but Many Side Effects Including Death –
Colon cleansing — it’s been described as a natural way to enhance well-being, but Georgetown University doctors say there’s no evidence to back that claim. In fact, their review of scientific literature, published August 1 in the August issue of The Journal of Family Practice, demonstrates that colon cleansing can cause side effects ranging from cramping to renal failure and death.
There can be serious consequences for those who engage in colon cleansing whether they have the procedure done at a spa or perform it at home,” says the paper’s lead author, Dr. Ranit Mishori. “There is an abundance of studies noting side effects following the use of cleansing products including cramping, bloating, nausea, vomiting, electrolyte imbalance and renal failure. Some herbal preparations have also been associated with aplastic anemia and liver toxicity,” she says
It’s important to remember the U.S. Food and Drug Administration has no authority to monitor these products. Mishori points out that colon cleansing services are increasingly being offered at spas or clinics by practitioners who call themselves ‘colon hygienists’ but they have no significant medical training. In fact, organizations such as the National Board for Colon Hydrotherapy and others who promote colon cleansing require hygienists to have little more than a high school diploma.
Mishori says there are much better ways to enhance well-being: “Eat a balanced diet, exercise regularly, get six to eight hours of sleep and see a doctor regularly.”
First Observational Test of the ‘Multiverse’ –
The theory that our universe is contained inside a bubble, and that multiple alternative universes exist inside their own bubbles — making up the ‘multiverse’ — is, for the first time, being tested by physicists.
Until now, nobody had been able to find a way to efficiently search for signs of bubble universe collisions — and therefore proof of the multiverse — in the CMB radiation, as the disc-like patterns in the radiation could be located anywhere in the sky. Additionally, physicists needed to be able to test whether any patterns they detected were the result of collisions or just random patterns in the noisy data.
One of many dilemmas facing physicists is that humans are very good at cherry-picking patterns in the data that may just be coincidence. Dr Daniel Mortlock, a co-author from the Department of Physics at Imperial College London, said: “It’s all too easy to over-interpret interesting patterns in random data (like the ‘face on Mars’ that, when viewed more closely, turned out to just a normal mountain), so we took great care to assess how likely it was that the possible bubble collision signatures we found could have arisen by chance.”
Did Earth Once Have Two Moons? –
For tens of millions of years—a mere sliver of astronomical time—the night sky above Earth may have been a bit more populous than it is today. For that brief period, our planet may have had not one but two moons, which soon collided and merged into our familiar lunar companion. No one would have been around to see the second moon—the lunar merger would have occurred nearly 4.5 billion years ago, shortly after Earth had formed.
The two-moon hypothesis, put forth in a study in the August 4 issue of Nature, would help explain why the moon’s two hemispheres are so different today. The familiar hemisphere facing Earth is covered by low, lava-filled plains (seen as the darker gray areas on the moon’s “face”), whereas the far side, which is never visible from Earth, is a collection of rugged, mountainous highlands. Those highlands, according to the new hypothesis, would be the remains of the smaller, short-lived satellite following its collision with the moon that now hangs overhead. The key is that the moonlet’s impact would be slow enough to pancake its material across one face of the moon rather than excavating a large crater.
The leading hypothesis for the moon’s creation itself involves an impact, this one a higher-speed crash of a Mars-size body into the nascent Earth. That collision, as the story goes, packed enough punch to kick up a ring of debris around Earth that coalesced into the moon. If an accompanying moonlet formed in the aftermath of that collision, simulations have shown, the system would be unstable, pushing the moonlet into a sudden demise in a collision with the dominant moon or with Earth. But certain orbital safe havens known as Trojan points, leading or trailing the moon in its orbit around Earth, would allow a moonlet to hang around for tens of millions of years before meeting its end.
By that time, the two objects would be at very different stages of evolution: a moonlet roughly one third the diameter of the moon would have cooled and solidified, whereas an ocean of magma would persist on the larger moon. In Jutzi and Asphaug’s computer simulations, the pancaking of a solid moonlet against a partly molten moon would provide enough material to create the elevated highlands on one hemisphere and would displace huge amounts of magma to the opposite hemisphere.
Chimp brains don’t shrink –
Other species experience declines in mental performance as they age, but only humans, it appears, actually lose brain mass. The human brain shrinks with age in what seems to be an evolutionarily new phenomenon, report Chet Sherwood of the George Washington University in Washington DC and his colleagues. They found that no parallel reduction in brain size seems to occur in our closest relative, the chimpanzee.
The researchers used magnetic resonance imaging to measure the volumes of whole brains, as well as regions of the frontal lobe and hippocampus, in 87 humans aged 22–88 and 99 chimpanzees aged 10–51. These volumes all fell with age in humans, but maintained a stable size in chimps. The team speculates that the shrinkage occurs because, compared with chimps, humans have evolved an extended lifespan, which amplifies normal cellular ageing processes.
If Science Takes A Wrong Turn, Who Rights It? –
One of the great strengths of science is that it can fix its own mistakes. “There are many hypotheses in science which are wrong,” the astrophysicist Carl Sagan once said. “That’s perfectly all right: it’s the aperture to finding out what’s right. Science is a self-correcting process.”
As a series of controversies over the past few months have demonstrated, science fixes its mistakes more slowly, more fitfully and with more difficulty than Sagan’s words would suggest. Science creates new theories better than it retracts old ones.
Why? One simple answer is that it takes a lot of time to look back over other scientists’ work and replicate their experiments. Scientists are busy people, scrambling to get grants and tenure. As a result, papers that attract harsh criticism may nonetheless escape the careful scrutiny required if they are to be refuted.
Even when scientists rerun an experiment, and even when they find that the original result is flawed, they still may have trouble getting their paper published. The reason is surprisingly mundane: journal editors typically prefer to publish ground-breaking new research, not dutiful replications.
Even when follow-up studies manage to see the light of day, they still don’t necessarily bring matters to a close. Sometimes the original authors will declare the follow-up studies to be flawed and refuse to retract their paper.
False, bad or inaccurate study, however, are still the exception rather than the rule. If the scientific community put more value on replication — by setting aside time, money and journal space — science would do a better job of living up to Carl Sagan’s words.
Five Things Most People Get Wrong About Memory –
Human memory has been shown again and again to be far from perfect. We overlook big things, forget details, conflate events. One famous experiment even demonstrated that many people asked to watch a video of people playing basketball failed to notice a person wearing a gorilla suit walk right through the middle of the scene.
So why does eyewitness testimony continue to hold water in courtrooms? A new nationwide survey of 1,500 U.S. adults shows that many people continue to have the wrong idea about how we remember—and what we forget.
- Memory works like a video camera, recording the world around us onto a mental tape that we can later replay – Nearly two thirds (63%) of those in the random telephone survey said that they agreed with this model of a passively recorded memory. This notion runs counter to research.
- An unexpected occurrence is likely to be noticed; even when people’s attention is elsewhere – More than three quarters (77.5%) of people thought that this would be the case. Clearly, they are unfamiliar with the gorilla suit study. That work and other research have shown that unexpected—and even preposterous—details frequently go unnoticed, and thus do not make it into memory.
- Hypnosis can improve memory; especially when assisting a witness in recalling details associated with a crime – Most memory experts disagree with this statement, but more than half (55.4 percent) of the surveyed public thought that it was accurate. Courts have already steered away from accepting testimony that was gathered through hypnosis.
- Amnesia sufferers usually cannot remember their identity or name – 82.7% of those surveyed shared this (incorrect) view of the condition. Most common forms of amnesia interfere with the formation of new long-term memories—usually as a result of a major brain injury. The researchers cite the movie Memento as a reasonably accurate portrayal of the condition
- The survey also found that nearly half (47.6%) of respondents said that once a memory is formed, it is set in stone – This is also not true, say the researchers: “Our memories can change even if we don’t realize they have changed,”
Glow in the dark dog –
Scientists clone beagle that glows fluorescent green.
Scientists in South Korea have used a cloning technique to ‘create’ a “glowing” dog, which they hope to use to investigate certain human diseases. The “glowing” effect in the two year old beagle named Tegon can be turned on and off with a doxycycline antibiotic.
In the scientific record books, Tegon joins a red fluorescent puppy named Ruppy and Mr. Green Genes the cat as all being human-modified animals that can glow.