Phage-Filled Mucus

Wednesday, May 22nd, 2013

Animals use mucus as a protective barrier in places like the gut and lungs, and that mucus is full of bacteria-eating viruses called phages:

These protect their hosts from infection by destroying incoming bacteria. In return, the phages are exposed to a steady torrent of microbes in which to reproduce.

Microbial ecologist Forest Rohwer found that mucus contained four times more phages than the surrounding environment:

Mucus mainly consists of huge molecular complexes called mucins, which are made up of thousands of glycan sugars attached to a central protein backbone. The team showed that phages stick to these sugars, which Barr likens to a “large biological bottlebrush”.

The glycans are constantly changing and extremely variable, but the phages have equally diverse proteins in their coats, which allow them to cling to this inconsistent environment. The team showed that the presence of phages reduced the number of bacteria that can attach to mucus by more than 10,000 times.

Barr says he thinks that the phage strains found most often in mucus will be those that target the most common bacteria, providing a sort of ‘mucus memory’ against the most relevant local microbes. But because mucus is continuously being shed and replenished, these relationships are in constant flux. Barr, Rohwer and the team are now trying to simulate the evolutionary dynamics within this realm of mucus.

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More Than Deliberate Practice

Tuesday, May 21st, 2013

Ericsson et al. found that top-tier experts differ from second-tier experts in the amount of deliberate practice they’d accumulated over the years. Famously, they found that it takes 10,000 hours of deliberate practice to master a skill like playing chess or playing a musical instrument.

Now Hambrick et al. have found that the cumulative amount of deliberate practice explains about a third of the variance in skill level between experts.

That leaves plenty of room for natural talent to play a role — but it also leaves room for quality of practice, coaching, etc.

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Treating one Disease by Causing Another

Tuesday, May 21st, 2013

Treating one disease by causing another is a mainstream therapeutic strategy, Bruce Charlton notes — especially in psychiatry:

Malarial Therapy of GPI (“General Paralysis of the Insane” — cerebral syphilis)

Patients with incurable and fatal GPI were deliberately infected with malaria. The very high pyrexia (temperature) killed the syphilis germ, but (hopefully) not the patient. The patient was then (hopefully) cured of their malaria using quinine.

Leucotomy/Lobotomy

Patients with chronic and incurable anxiety or tension were deliberately given brain damage, cutting off the frontal lobes of the cerebral cortex from the rest of the brain. This made the patients docile and indifferent – which was presumed to be an improvement. The procedure became so popular that brain damage was inflicted on patients with less severe and probably temporary anxiety and other conditions, too.

Neuroleptics/Antipsychotics create Parkinson’s disease (or, rather, Parkinsonism, which may be reversible) for the treatment of fear, agitation, delusions, hallucinations, and hyperactivity

Patients with a range of very distressing psychological and psychotic symptoms were deliberately made to suffer from Parkinson’s disease by giving them dopamine blocking drugs. As well as producing the physical symptoms of Parkinsonism (tremor, stiffness, movement disorders), the drugs produced the psychological symptoms of Parkinsonism – emotional blunting and demotivation. Patients could no longer be bothered to respond to delusions and hallucinations.

Unfortunately patients could no longer be bothered to do anything else, either and became asocial, withdrawn, idle, and without the ability to experience pleasure. Also, when treatment was sustained, the drugs were found to have a permanent effect (tardive dyskinesia) and to create dependence — such that withdrawal often caused a psychotic breakdown.

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Crazy Ants Are Displacing Fire Ants

Monday, May 20th, 2013

Crazy ants are displacing fire ants — and people want their fire ants back:

The Tawny crazy ant invasion is the most recent in a series of ant invasions from South America brought on by human movement. The Argentine ant invaded through the port of New Orleans in about 1891. In 1918 the black imported fire ant showed up in Mobile, Ala. Then in the 1930s, the red imported fire ant arrived in the U.S. and began displacing the black fire ant and the Argentine ants.

The UT researchers studied two crazy ant invasion sites on the Texas Gulf Coast and found that in those areas where the Tawny crazy ant population is densest, fire ants were eliminated. Even in regions where the crazy ant population is less dense, fire ant populations were drastically reduced. Other ant species, particularly native species, were also eliminated or diminished.

LeBrun said crazy ants are much harder to control than fire ants. They don’t consume most of the poison baits that kill fire ant mounds, and they don’t have the same kinds of colony boundaries that fire ants do. That means that even if they’re killed in a certain area, the supercolony survives and can swarm back over the area.

“They don’t sting like fire ants do, but aside from that they are much bigger pests,” he said. “There are videos on YouTube of people sweeping out dustpans full of these ants from their bathroom. You have to call pest control operators every three or four months just to keep the infestation under control. It’s very expensive.”

LeBrun said that in northern Argentina and southern Brazil, where the ants are native, populations are likely held in check by other ant species and a variety of natural enemies. In the U.S. there is no such natural control.

Here the crazy ants can attain densities up to 100 times as great as all other ants in the area combined. In the process, they monopolize food sources and starve out other species. LeBrun said the crazy ants, which are omnivorous, may also directly attack and kill other ant and arthropod species.

I, for one, welcome our new insect overlords.

Posted in Animals, Science | No Comments »

Antibiotics could cure 40% of chronic back pain patients

Monday, May 20th, 2013

Danish researchers have found yet another malady caused by bacterial infection — chronic back pain:

Specialists who deal with back pain have long known that infections are sometimes to blame, but these cases were thought to be exceptional. That thinking has been overturned by scientists at the University of Southern Denmark who found that 20% to 40% of chronic lower back pain was caused by bacterial infections.

[...]

The Danish team describe their work in two papers published in the European Spine Journal. In the first report, they explain how bacterial infections inside slipped discs can cause painful inflammation and tiny fractures in the surrounding vertebrae.

Working with doctors in Birmingham, the Danish team examined tissue removed from patients for signs of infection. Nearly half tested positive, and of these, more than 80% carried bugs called Propionibacterium acnes.

The microbes are better known for causing acne. They lurk around hair roots and in the crevices in our teeth, but can get into the bloodstream during tooth brushing. Normally they cause no harm, but the situation may change when a person suffers a slipped disc. To heal the damage, the body grows small blood vessels into the disc. Rather than helping, though, they ferry bacteria inside, where they grow and cause serious inflammation and damage to neighbouring vertebrae that shows up on an MRI scan.

In the second paper, the scientists proved they could cure chronic back pain with a 100-day course of antibiotics. In a randomised trial, the drugs reduced pain in 80% of patients who had suffered for more than six months and had signs of damaged vertebra under MRI scans.

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Games that let you do real-life science

Thursday, May 16th, 2013

I remember when Foldit was new:

Foldit is the granddaddy of crowd-sourced research games and has proven that games are a viable way to get results. Players were able to discover the structure of a monkey HIV virus, a problem that had stumped scientists for over ten years, in just ten days. The game itself is a 3D folding puzzle. Players are challenged to fold proteins into compact designs and are scored on various criteria like size and whether hydrophobic side chains are buried inside the structure. Players can work alone or with teams, to compete in puzzles and challenges.

Now there are many such games that let you do real-life science.

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Bicep Size Predicts Politics

Wednesday, May 15th, 2013

A new Psychological Science study examines The Ancestral Logic of Politics:

Over human evolutionary history, upper-body strength has been a major component of fighting ability. Evolutionary models of animal conflict predict that actors with greater fighting ability will more actively attempt to acquire or defend resources than less formidable contestants will. Here, we applied these models to political decision making about redistribution of income and wealth among modern humans.

In studies conducted in Argentina, Denmark, and the United States, men with greater upper-body strength more strongly endorsed the self-beneficial position: Among men of lower socioeconomic status (SES), strength predicted increased support for redistribution; among men of higher SES, strength predicted increased opposition to redistribution.

Because personal upper-body strength is irrelevant to payoffs from economic policies in modern mass democracies, the continuing role of strength suggests that modern political decision making is shaped by an evolved psychology designed for small-scale groups.

(Hat tip to Ronald Bailey.)

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The Complex and Pathogen-Laden World of Ticks

Wednesday, May 15th, 2013

Carl Zimmer examines the complex and pathogen-laden world of ticks:

Foxes were originally very abundant in the eastern United States, where they feasted on small mammals like white-footed mice. But the past few decades have not been good to them. “Fox harvests in the Northeast have declined substantially,” says Levi.

A number of studies suggest that coyotes have been responsible for the decline. Originally, foxes coexisted with wolves in the eastern and midwestern United States. Once wolves were eradicated, coyotes expanded from the Midwest to take their place. Coyotes kill foxes or scare them out of range.

Levi and his colleagues built a mathematical model of how these changes can affect rates of Lyme disease. When foxes disappear, the model suggests, numbers of small mammals like white-footed mice boom, feeding a growing population of ticks and their pathogens. For evidence, Levi points to historical records from sites across the Midwest and eastern United States. In some places, Lyme disease rates have gone up even though the deer population has not. But the rates in those places match up nicely with a decline in fox numbers.

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Females and Eating Disorders

Friday, May 3rd, 2013

Females are four to 10 times more likely than males to have an eating disorder — presumably because of social pressure to be thin.

But female rats are also much more likely than male rats to have an eating disorder:

Klump and colleagues ran a feeding experiment with 30 female and 30 male rats over a two-week period, replacing the rodents’ food pellets periodically with vanilla frosting. They found that the rate of binge eating “proneness” (i.e., the tendency to consume the highest amount of frosting across all feeding tests) was up to six times higher in female as compared to male rats.

Posted in Animals, Fitness, Science | 1 Comment »

Will Obamacare work?

Thursday, May 2nd, 2013

A new study out of Oregon shows Medicaid’s limits:

In its second-year results, the Oregon Health Insurance Experiment, which randomly selected 10,000 people in Oregon to get Medicaid (only about 6,300 actually got the benefit), and then compared them with a randomly selected control group, found that those who got Medicaid did not on average have healthier blood pressure, cholesterol levels, or diabetic blood pressure control than those who did not get Medicaid. Those with Medicaid did see some reduction in out of pocket health expenses. They were also less likely to be diagnosed with depression.

The Medicaid recipients also ended up utilizing a lot more health care — care that has to be paid for — than those who didn’t get coverage. But they didn’t use the emergency room any less than the control group.

How is this being presented in the media? A bit differently…

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In Defense of Working Memory Training

Tuesday, April 30th, 2013

Scott Barry Kaufman speaks out in defense of working memory training:

Cook based his conclusion [that brain games are bogus] on a recent review by Monica Melby-Lervag and Charles Hulme. Partly consistent with Cook’s statement, the researchers saw little evidence for the generalization of working memory training to other mental skills such as reading comprehension, word decoding, and arithmetic. But that’s not all they found. The researchers also found that working memory training programs do produce reliable short-term improvements in both verbal and visuospatial working memory skills. On average, the effect sizes were moderate, but in some cases the effects were actually quite large and rather impressive for brief training regimes which only lasted 12 hours (on average). In fact, the largest effects were found for Cogmed working memory training programs. So while Cook is quite right to criticize Cogmed for claiming too much in their promotional materials, I believe he is too quick to dismiss large and reliable short-term improvements in working memory as meaningless in the real world.

Working memory involves the ability to maintain and manipulate information in one’s mind while ignoring irrelevant distractions and intruding thoughts. Working memory skills are essential for everyday intellectual functioning. Multiple research studies show that the inability to control one’s train of thought has important real world consequences, from poor reading comprehension to unhappiness. Therefore, just because a working memory training program doesn’t generalize to other cognitive functions doesn’t mean that the program doesn’t make people “smarter,” at least in respect to one key aspect of intellectual functioning. After all, intelligence isn’t a single ability. There is an emerging consensus among intelligence researchers that general cognitive ability is comprised of multiple interacting cognitive functions, and working memory is one of those crucial intellectual functions.

A telling finding of the Melby-Larvag and Hulme review (but not mentioned by Cook) is that age was a significant moderating variable on strength of training. Younger children (below the age of 10 years) showed significantly larger benefits from verbal working memory training than older children (11-18 years of age). This suggests that lumping people together who are at different stages in their cognitive development can obscure some truly meaningful effects. I imagine if the researchers also included elderly individuals in their analysis (e.g., those above the age of 60), they would have found effect sizes resembling what they found for the youngest age groups (alas, such cognitive decline is part of life).

But equally as troublesome, the researchers didn’t look at other crucial moderating variables such as personality, motivation, learning disabilities, mental illness, and socioeconomic status. I believe each and every one of these variables also matter, and ought to be considered in grand reviews of the literature.

Take personality. In one study, participants scoring higher in conscientiousness showed greater improvement in working memory during working memory training compared to less conscientious participants, but they showed less transfer to a measure of fluid reasoning. This suggests that highly conscientious individuals may develop task-specific strategies that prevent generalizing effects beyond the specific skills that are trained. What’s more, participants scoring higher in neuroticism (a proxy for anxiety) showed greater improvement on an easier version of a working memory task compared to participants lower in neuroticism, but displayed lower training scores on a difficult version of the task. It seems that in the easier version, higher levels of emotion may have been an advantage, allowing highly neurotic individuals to maintain their concentration and vigilance, whereas on the more difficult version of the task they became overwhelmed by their anxiety. These nuanced effects suggest that personal characteristics should be taken into account when considering the effectiveness of cognitive training.

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Is Fairness About Clear Fitness Signals?

Monday, April 29th, 2013

Giving everyone equal rights means giving the strong license to oppress the weak, Fitzhugh said. That’s kind of the point, Robin Hanson might say:

“Fairness” is often described in terms of equality of outcomes. But in a game, the “fairest” rules are often those that make the ablest players mostly likely to win, instead of those that distribute wins most evenly among players.

Even outside of games, a wide range of otherwise puzzling common intuitions about fairness can be understood if the fundamental “game” of life is seen as wooing, i.e., attracting mates by showing that you have fit genes. The fairest social institutions are then those in which success correlates as much as possible with genetic fitness.

For example, it can seem fair that the most attractive witty athletic folks get more mates and money, but seem unfair that the rich can buy better education for their children. Makeup can seem fair, while breast implants seem unfair.

(Hat tip to sark.)

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Human Effect Matrix

Monday, April 29th, 2013

Examine.com has compiled a database of research papers on nutritional supplements and produced a Human Effect Matrix:

For every supplement in our database, a handy table will tell you what effect each supplement has and how noticeable that effect is.

Does Supplement X help with Y? Now you’ll know.

Creatine? It has a minor effect in increasing your testosterone, but a strong effect in increasing your power output. What about fish oil? It has actually has a notable effect in decreasing depression!

Best of all, the Human Effect Matrix isn’t on the supplement pages only. They are also on the effect pages themselves. Want to know which supplements impact inflammation? Done! Do any supplements help you add muscle? Now you know. (Spoiler: they all have, at most, a minor effect).

What we’ve done is removed all the mysticism, hyperbole, and marketing-speak used to talk about supplements. It’s all tabulated and organized for your perusal, and it’s all backed with citations with human-studies.

To get you going, here are a few popular and a few interesting supplements:

Posted in Fitness, Science | 2 Comments »

Deep Learning

Sunday, April 28th, 2013

Artificial intelligence is always right around the corner. Now deep learning looks like it might deliver:

In the mid-1980s, Hinton and others helped spark a revival of interest in neural networks with so-called “deep” models that made better use of many layers of software neurons. But the technique still required heavy human involvement: programmers had to label data before feeding it to the network. And complex speech or image recognition required more computer power than was then available.

Finally, however, in the last decade ­Hinton and other researchers made some fundamental conceptual breakthroughs. In 2006, Hinton developed a more efficient way to teach individual layers of neurons. The first layer learns primitive features, like an edge in an image or the tiniest unit of speech sound. It does this by finding combinations of digitized pixels or sound waves that occur more often than they should by chance. Once that layer accurately recognizes those features, they’re fed to the next layer, which trains itself to recognize more complex features, like a corner or a combination of speech sounds. The process is repeated in successive layers until the system can reliably recognize phonemes or objects.

Like cats. Last June, Google demonstrated one of the largest neural networks yet, with more than a billion connections. A team led by Stanford computer science professor Andrew Ng and Google Fellow Jeff Dean showed the system images from 10 million randomly selected YouTube videos. One simulated neuron in the software model fixated on images of cats. Others focused on human faces, yellow flowers, and other objects. And thanks to the power of deep learning, the system identified these discrete objects even though no humans had ever defined or labeled them.

What stunned some AI experts, though, was the magnitude of improvement in image recognition. The system correctly categorized objects and themes in the ­YouTube images 16 percent of the time. That might not sound impressive, but it was 70 percent better than previous methods. And, Dean notes, there were 22,000 categories to choose from; correctly slotting objects into some of them required, for example, distinguishing between two similar varieties of skate fish. That would have been challenging even for most humans. When the system was asked to sort the images into 1,000 more general categories, the accuracy rate jumped above 50 percent.

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Public’s Knowledge of Science and Technology

Saturday, April 27th, 2013

The public’s knowledge of science and technology is… limited.  Take this Pew Research quiz, and realize that getting all 13 questions right puts you in the top seven percent of Americans.

The quiz starts with four true-false questions. What percentage of Americans got each of these questions right?  Let’s see: 66, 47, 48, and 77.  That’s not too far from a trained ape’s success rate of 50 percent.

What percentage of American college grads got each one right?  82, 59, 58, and 85.

Anyway, Americans seem to know what sunscreen is for, but they don’t know much about our atmosphere.

Posted in Education, Science | 3 Comments »

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