Category Archives: Science

Non-infectious Prion Protein Linked to Alzheimer’s Disease

‘Harmless’ prion protein linked to Alzheimer’s disease

Non-infectious prion proteins found in the brain may contribute to Alzheimer’s disease, researchers have found.
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normal prion proteins produced naturally in the brain interact with the amyloid-Î² peptides that are hallmarks of Alzheimer’s disease. Blocking this interaction in preparations made from mouse brains halted some neurological defects caused by the accumulation of amyloid-Î² peptide. It was previously thought that only infectious prion proteins, rather than their normal, non-infectious counterparts, played a role in brain degeneration.
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Alzheimer’s disease has long been linked to the build-up of amyloid-Î² peptides, first into relatively short chains known as oligomers, and then eventually into the long, sticky fibrils that form plaques in the brain. The oligomeric form of the peptide is thought to be toxic, but exactly how it acts in the brain is unknown.

Poor Results on Evolution and Big Bang Questions Omitted From NSF Report

Evolution, Big Bang Polls Omitted From NSF Report by Yudhijit Bhattacharjee

The section, which was part of the unedited chapter on public attitudes toward science and technology, notes that 45% of Americans in 2008 answered true to the statement, “Human beings, as we know them today, developed from earlier species of animals.” The figure is similar to previous years and much lower than in Japan (78%), Europe (70%), China (69%), and South Korea (64%). The same gap exists for the response to a second statement, “The universe began with a big explosion,” with which only 33% of Americans agreed.

The USA continues to lag far behind the rest of the world in this basic science understanding. Similar to how we lag in other science and mathematical education. Nearly Half of Adults in the USA Don’t Know How Long it Takes the Earth to Circle the Sun.

Jon Miller, a science literacy researcher at Michigan State University in East Lansing who authored the survey 3 decades ago and conducted it for NSF until 2001. “Evolution and the big bang are not a matter of opinion. If a person says that the earth really is at the center of the universe, even if scientists think it is not, how in the world would you call that person scientifically literate? Part of being literate is to both understand and accept scientific constructs.”

I completely agree. People have the right to their opinions. But those opinions which are related to scientific knowledge (whether it is about evolution, the origin of the universe, cancer, the speed of light, polio vaccinations, multi-factorial designed experiments, magnetic fields, chemical catalysts, the effectiveness of antibiotics against viral infections, electricity, optics, bioaccumulation, etc.) are part of their scientific literacy. You can certainly believe antibiotics are affective against viral infections but that is an indication you are scientifically illiterate on that topic.

2006 NSF chapter that included the results
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Why Wasn’t the Earth Covered in Ice 4 Billion Years Ago – When the Sun was Dimmer

Climate scientists from all over the globe are now able to test their climate models under extreme conditions thanks to Professor Minik Rosing, University of Copenhagen. Rosing has solved one of the great mysteries and paradoxes of our geological past, namely, “Why the earth’s surface was not just one big lump of ice four billion years ago when the Sun’s radiation was much weaker than it is today.” Until now, scientists have presumed that the earth’s atmosphere back then consisted of 30% carbon dioxide (CO2) which ensconced the planet in a protective membrane, thereby trapping heat like a greenhouse.

The faint early sun paradox
In 1972, the late, world famous astronomer Carl Sagan and his colleague George Mullen formulated “The faint early sun paradox. ” The paradox consisted in that the earth’s climate has been fairly constant during almost four of the four and a half billion years that the planet has been in existence, and this despite the fact that radiation from the sun has increased by 25-30 percent.

The paradoxical question that arose for scientists in this connection was why the earth’s surface at its fragile beginning was not covered by ice, seeing that the sun’s rays were much fainter than they are today. Science found one probable answer in 1993, which was proffered by the American atmospheric scientist, Jim Kasting. He performed theoretical calculations that showed that 30% of the earth’s atmosphere four billion years ago consisted of CO2. This in turn entailed that the large amount of greenhouse gases layered themselves as a protective greenhouse around the planet, thereby preventing the oceans from freezing over.

Mystery solved
Now, however, Professor Minik Rosing, from the Natural History Museum of Denmark, and Christian Bjerrum, from the Department of Geography and Geology at University of Copenhagen, together with American colleagues from Stanford University in California have discovered the reason for “the missing ice age” back then, thereby solving the sun paradox, which has haunted scientific circles for more than forty years.

Professor Minik Rosing explains, “What prevented an ice age back then was not high CO2 concentration in the atmosphere, but the fact that the cloud layer was much thinner than it is today. In addition to this, the earth’s surface was covered by water. This meant that the sun’s rays could warm the oceans unobstructed, which in turn could layer the heat, thereby preventing the earth’s watery surface from freezing into ice. The reason for the lack of clouds back in earth’s childhood can be explained by the process by which clouds form. This process requires chemical substances that are produced by algae and plants, which did not exist at the time. These chemical processes would have been able to form a dense layer of clouds, which in turn would have reflected the sun’s rays, throwing them back into the cosmos and thereby preventing the warming of earth’s oceans. Scientists have formerly used the relationship between the radiation from the sun and earth’s surface temperature to calculate that earth ought to have been in a deep freeze during three billion of its four and a half billion years of existence. Sagan and Mullen brought attention to the paradox between these theoretical calculations and geological reality by the fact that the oceans had not frozen. This paradox of having a faint sun and ice-free oceans has now been solved.”

CO2 history iluminated
Minik Rosing and his team have by analyzing samples of 3.8-billion-year-old mountain rock from the world’s oldest bedrock, Isua, in western Greenland, solved the “paradox”.

But more importantly, the analyses also provided a finding for a highly important issue in today’s climate research – and climate debate, not least: whether the atmosphere’s CO2 concentration throughout earth’s history has fluctuated strongly or been fairly stable over the course of billions of years.

“The analyses of the CO2-content in the atmosphere, which can be deduced from the age-old Isua rock, show that the atmosphere at the time contained a maximum of one part per thousand of this greenhouse gas. This was three to four times more than the atmosphere’s CO2-content today. However, not anywhere in the range of the of the 30 percent share in early earth history, which has hitherto been the theoretical calculation. Hence we may conclude that the atmosphere’s CO2-content has not changed substantially through the billions of years of earth’s geological history. However, today the graph is turning upward. Not least due to the emissions from fossil fuels used by humans. Therefore it is vital to determine the geological and atmospheric premises for the prehistoric past in order to understand the present, not to mention the future, in what pertains to the design of climate models and calculations,” underscores Minik Rosing.

Full press release from the University of Copenhagen in Denmark.

Gravity Emerges from Quantum Information, Say Physicists

One of the hottest new ideas in physics is that gravity is an emergent phenomena; that it somehow arises from the complex interaction of simpler things.
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perhaps the most powerful idea to emerge from Verlinde’s approach is that gravity is essentially a phenomenon of information.
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Over recent years many results in quantum mechanics have pointed to the increasingly important role that information appears to play in the Universe. Some physicists are convinced that the properties of information do not come from the behaviour of information carriers such as photons and electrons but the other way round. They think that information itself is the ghostly bedrock on which our universe is built.

Gravity has always been a fly in this ointment. But the growing realisation that information plays a fundamental role here too, could open the way to the kind of unification between the quantum mechanics and relativity that physicists have dreamed of.

This speculative physics is fascinating. Open access paper: Gravity from Quantum Information.

Using Bacteria to Power Microscopic Machines

Scientists at the U.S. Department of Energy’s (DOE) Argonne National Laboratory and Northwestern University have discovered that common bacteria can turn microgears when suspended in a solution, providing insights for designs of bio-inspired dynamically adaptive materials for energy.

“The ability to harness and control the power of bacterial motion is an important requirement for further development of hybrid biomechanical systems driven by microorganisms,” said Argonne physicist and principal investigator Igor Aronson. “In this system, the gears are a million times more massive than the bacteria.”

A few hundred bacteria work together in order to turn the gear. When multiple gears are placed in the solution with the spokes connected as in a clock, the bacteria will turn both gears in opposite directions, causing the gears to rotate in synchrony—even for long stretches of time.

“There exists a wide gap between man-made hard materials and living tissues; biological materials, unlike steel or plastics, are ‘alive,'” Aronson said. “Our discovery demonstrates how microscopic swimming agents, such as bacteria or man-made nanorobots, in combination with hard materials, can constitute a ‘smart material’ which can dynamically alter its microstructures, repair damage, or power microdevices.”

Surprise Shrimp Under Antarctic Ice

A three-inch long Lyssianasid amphipod found 600 feet beneath the Ross Ice Shelf stars in a recent popular webcast (see below). NASA scientists were using a borehole camera to look back up towards the ice surface when they spotted this pinkish-orange creature swimming beneath the ice.

Stacy Kim of Moss Landing Marine Laboratory was the first biologist to see the video and immediately recognized it as a Lyssianasid amphipod. It was about 3 inches long and Stacy concluded that this meant there was quite an extensive biological community under the ice here – even 20 miles from open water.

Taste Cells in the Stomach and Intestine

Stomach’s Sweet Tooth

Taste, scientists are discovering, is a whole-body sensation. There are taste cells in the stomach, intestine and, evidence suggests, the pancreas, colon and esophagus. These sensory cells are part of an ancient battalion tasked with guiding food choices
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Newly discovered taste cells in the gut appear to send a “prepare for fuel” message to the body, a finding that may explain a link between diet soda and diabetes risk.
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The gut’s taste cells appear to be built from the same machinery as the taste cells of the tongue, the structures of which scientists have only recently nailed down. Taste cells interact with what are called “tastants” via receptors, specialized proteins that protrude from cell walls and bind to specific molecules drifting by. When a tastant binds to a receptor, it signals other molecules that, in the mouth, immediately send an “accept” or “reject” message to the brain.
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Gut taste cells appear to regulate, in part, secretion of insulin, a hormone crucial for telling body tissues whether they should tap newly arrived glucose or valuable stored fat for energy.

Engineering Mosquitoes to be Flying Vaccinators

Mosquitoes Engineered Into Flying Vaccinators by Emily Singer

Researchers in Japan have transformed mosquitoes into vaccine-carrying syringes by genetically engineering the insects to express the vaccine for leishmaniasis–a parasitic disease transmitted by the sandfly–in their saliva. According to a study in Insect Molecular Biology, mice bitten by these mosquitoes produced antibodies against the parasite. It’s not yet clear whether the immune response was strong enough to protect against infection.

“Following bites, protective immune responses are induced, just like a conventional vaccination but with no pain and no cost,” said lead researcher Shigeto Yoshida, from the Jichi Medical University in JapanYoshida, in a press release from the journal. “What’s more continuous exposure to bites will maintain high levels of protective immunity, through natural boosting, for a life time. So the insect shifts from being a pest to being beneficial.”

Researchers consider the project more of a proof of principle experiment than a viable public health option, at least for now.

Very cool.

Invisible Worlds: Fastest Thing on the Planet

Fun with Fungi.

Statistical Errors in Medical Studies

I have written about statistics, and various traps people often fall into when examining data before (Statistics Insights for Scientists and Engineers, Data Can’t Lie – But People Can be Fooled, Correlation is Not Causation, Simpson’s Paradox). And also have posted about reasons for systemic reasons for medical studies presenting misleading results (Why Most Published Research Findings Are False, How to Deal with False Research Findings, Medical Study Integrity (or Lack Thereof), Surprising New Diabetes Data). This post collects some discussion on the topic from several blogs and studies.

HIV Vaccines, p values, and Proof by David Rind

if vaccine were no better than placebo we would expect to see a difference as large or larger than the one seen in this trial only 4 in 100 times. This is distinctly different from saying that there is a 96% chance that this result is correct, which is how many people wrongly interpret such a p value.
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So, the modestly positive result found in the trial must be weighed against our prior belief that such a vaccine would fail. Had the vaccine been dramatically protective, giving us much stronger evidence of efficacy, our prior doubts would be more likely to give way in the face of high quality evidence of benefit.
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While the actual analysis the investigators decided to make primary would be completely appropriate had it been specified up front, it now suffers under the concern of showing marginal significance after three bites at the statistical apple; these three bites have to adversely affect our belief in the importance of that p value. And, it’s not so obvious why they would have reported this result rather than excluding those 7 patients from the per protocol analysis and making that the primary analysis; there might have been yet a fourth analysis that could have been reported had it shown that all important p value below 0.05.

How to Avoid Commonly Encountered Limitations of Published Clinical Trials by Sanjay Kaul, MD and and George A. Diamond, MD

Trials often employ composite end points that, although they enable assessment of nonfatal events and improve trial efficiency and statistical precision, entail a number of shortcomings that can potentially undermine the scientific validity of the conclusions drawn from these trials. Finally, clinical trials often employ extensive subgroup analysis. However, lack of attention to proper methods can lead to chance findings that might misinform research and result in suboptimal practice.

Why Most Published Research Findings Are False by John P. A. Ioannidis
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