A quick heads-up on some new carnivals. Go sustain your scientific hunger at:

• Cognitive Daily, hosting the new Encephalon Go on. The power of Munger compels you.  
• The Conservation Report, with the new Carnival of the Green
• Doc Gurley, with an almighty Grand Rounds smackdown.

Forget ‘smart drugs’ or brain-training video games. According to new research, a deceptively simple memory task can do what no drug or game has done before – it can boost your ‘fluid intelligence‘, your ability to adapt your powers of reasoning to new challenges. Fluid intelligence doesn’t rely on previous knowledge, skills or experience. It’s at work when we solve new problems or puzzles, when we draw inferences and spot patterns, and when we test ideas and design experiments. To see what I mean, try testing yours.

Fluid intelligence appears to be strongly influenced by inherited genetic factors and is closely related to success in both the classroom and the workplace. The ability plays such a central role in our lives that it begs an obvious question: is there any way of improving your fluid intelligence through training?

Video game manufacturers would like you to think so. Games like Dr Kawashima’s Brain Training and Big Brain Academy are suggestively marketed as ways of improving your brain’s abilities through the medium of number problems, Sudoku and word puzzles. As a result, your brain will allegedly become younger. And look, Nicole Kidman likes them. The pitch is certainly a successful one – these games are bestsellers and are increasingly joined by a swarm of imitators. Last year, the worth of the US brain-training market alone was estimated at about $80 million.

Whether these products actually work is open to debate but there is certainly no strong evidence that they do anything beyond improving performance at specific tasks. That seems fairly obvious – people who repeatedly practice the same types of tests, such as number sequences, will become better at them over time but may not improve in other areas, like memory or spatial awareness. But acquiring Jedi-levels skills in one specific task is a far cry from increasing your overall fluid intelligence; it’d be like saying that you’re a better musician because your scales are second-to-none.

Nonetheless, Susanne Jaeggi from the University of Michigan has developed a training programme involving a challenging memory task, which does appears to improve overall fluid intelligence. The trainees do better in intelligence tests that have nothing to do with the training task itself and the more training they receive, the higher their scores.

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They say that size doesn’t matter, but try telling that to bacteria. Most are very small, for they rely heavily on passive diffusion to ferry important nutrients and molecules across their membranes. To ensure that this happens quickly enough, bacteria need to ensure that their surface area is large enough relative to their volume – become too big and they won’t be able to import enough nutrients to support their extra size.

These constraints greatly limit the size of bacteria. The larger ones solve the problem by being extremely long and slender, or by using an internal compartment called a vacuole to push their insides to their outer edges. But even these solutions have their limits, and the simple fact is that most bacterial cells are far smaller than those of the more complex eukaryotes – a group that includes all known animals, plants and fungi.

But one group of bacteria – Epulopiscium sp. – flouts this rule. It has developed a genetic trick that allows it to grow to (relatively) gigantic proportions. While a typical bacterium like Escherichia coli is a mere 2 micrometers long, Epulopiscium can grow up to a length of 300 micrometers. That’s not much smaller than the full stop at the end of this sentence and certainly comparable to most eukaryotic cells. And the secret to its mammoth size? DNA, and lots of it.

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If it looks like a dead cell and it feels like a dead cell, be careful – it could be a virus. Viruses are experts at infiltrating and exploiting cells but some are so big that they need to use special tricks. The Vaccinia virus is one of these. It belongs to the same family as the more infamous variola virus that causes smallpox. This group are among the largest of viruses, dwarfing many other types by a factor of ten. But despite its size, Vaccinia relies on stealth rather than brute force.

It’s a mimic and it disguises itself as cellular flotsam. Vaccinia carries a molecular tag on its surface called phosphatidylserine, which is usually found on the remains of cells that have died naturally. Its presence dupes other host cells into absorbing the virus as part of their general clean-up duties.

Jason Mercer and Ari Helenius from the EHT in Zurich discovered this piece of molecular trickery by tagging individual virus particles with a protein that glowed yellow, to track their movements as they stormed into a cell. Each invasion began as a virus latched onto thin protrusions called filopodia and used these as anchors to inch its way towards the main cell body (watch it happen on a Quicktime video).

When the virus reached the cell proper, it triggered a process called macropinocytosis, that cells normally use to import large volumes of fluid or molecules that are too big to pull in through other means. The cell’s membrane developed spherical blisters called “blebs”, which swelled outward only to collapse again within half a minute. The touch of a single virus was enough to produce about a hundred blebs all over the cell’s surface and as they retracted, they smuggled the virus in with them (again, watch it happen on a Quicktime video).

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You all know the score. A train leaves one city travelling at 35 miles per hour and another races toward it at 25 miles an hour from a city 60 miles away. How long do they take to meet in the middle? Leaving aside the actual answer of 4 hours (factoring in signalling problems, leaves on the line and a pile-up outside Clapham Junction), these sorts of real-world scenarios are often used as teaching tools to make dreary maths “come alive” in the classroom.

Except they don’t really work. A new study shows that far from easily grasping mathematical concepts, students who are fed a diet of real-world problems fail to apply their knowledge to new situations. Instead, and against all expectations, they were much more likely to transfer their skills if they were taught with abstract rules and symbols.

The use of concrete, real-world examples is a deeply ingrained part of the maths classroom. Its advantages have never really been tested properly, for they appear to be straightforward. Maths is difficult because it is a largely abstract field and is both difficult to learn and to apply in new situations. The solution seems obvious: present students with many familiar examples that illustrate the concepts in question and they can make connections between their existing knowledge and the more difficult concepts they are trying to pick up.

The train problem is a classic example. Another is the teaching of probability with rolls of a die, or by asking people to pick red marbles from a bag containing both blue and red ones. The idea is that, armed with these examples, students will recognise similar problems and apply what they have learned. It’s a technique deeply rooted in common sense, which is probably as good an indicator as any that it might be totally wrong.

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In the story of climate change, humans and the carbon dioxide we pump into the atmosphere are the villains of the piece. Now, it seems that we have an accomplice and a most unexpected one at that. It lives in the pine forests of North America and even though it measures just 5 millimetres in length, it is turning these woods from carbon sinks into carbon sources. It’s the mountain pine beetle.

The beetle bores into pine trees and feeds from nutrient-carrying vessels called phloem. It also lays its eggs there. Once a beetle has colonised a pine, it pumps out pheromones that attract others, which descend on the tree en masse and overwhelm its defences. The infestation damages the phloem to such an extent that the tree effectively dies of malnutrition within weeks. A single beetle can live for up to a year, giving it plenty of time to damage several trees.

Normally, the beetles target weak, old or dying trees and in this capacity, they speed the growth of young trees. But occasionally, their numbers erupt in large-scale outbreaks and British Columbia is currently facing the largest one ever recorded. They have infected an area of forest the size of Greece and the scale of the epidemic is ten times worse than any previous incident. The damage is even obvious from the air, for the needles of infected trees turn red within the first year and gray as they succumb further (as illustrated after the jump…)

The outbreak is bad news for the local ecosystem and the forestry industry alike. But Werner Kurz from the Canadian Forest Service has found a subtler impact of the beetle’s actions – they will transform the local forest from a carbon sink into a carbon source. Dead trees are in no position to soak up carbon dioxide from the air, and their decay will release even more carbon back into their environment.

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The easiest way to talk to someone else is face-to-face. If you can see the movements of a person’s lips and facial muscles, you can more easily work out what they’re saying, a fact made obvious if you’re trying to have a conversation in a noisy environment. These visual cues clue our brains in on how best to interpret the signals coming from our ears.

But what happens when that’s not possible, like when you’re chatting on the phone or listening to a recorded message? New research suggests that if you’ve spoken to someone before, your brain uses memories of their face to help decode what they’re saying when they’re not in front of you. Based on previous experience, It runs a simulation of the speaker’s face to fill in any information missing from the sound stream alone.

These results contradict a classical theory about hearing – the “auditory-only model” – which suggest that the brain deciphers the spoken word using only the signals it receives from the ears. The model has been opposed before, by earlier studies which found that people are better at identifying a speaker by voice if they have briefly seen that person speaking before. Katherina von Kriegstein from University College London extended these discoveries by showing that previous experience also helps us to work out what’s being said, as well as who said it.

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It’s late at night and although I want to finish this post, I’m pretty shattered. At the moment, I sorely need to boost my concentration and attentiveness and stave off the effects of fatigue. In lieu of actually getting some sleep, the ability to pop a little pill that will have the same effect sounds pretty enticing. Unfortunately (or perhaps luckily), the closest thing I have available is some coffee in the kitchen.

But for many people, taking a pill to sharpen your mental faculties – a so-called “cognitive enhancer” – is a much easier deal. A large number of prescription drugs can indeed give you a little mental boost, including amphetamine and methylphenidate (more familiarly known by its brand name Ritalin). Both the use and the range of such drugs are on the rise and they seem capable of stimulating debate just as readily as they do the brain.

They have their medical uses; as Ritalin, methylphenidate is used to treat attention deficit hyperactivity disorder (ADHD) and, less commonly, narcolepsy. Even this is not without controversy, but the fact that they seem to have the same enhancing effects in healthy people opens up the potential for recreational use, and that is far more divisive.

Last year, Nature published a commentary which looked into the ethics of such drugs and sparked off a heated debate in a Nature Network forum and among fellow bloggers. More recently, the magazine released the results of an informal survey of over 1,400 readers, which showed that about 20% admitted to using cognitive enhancers for non-medical reasons and a far higher proportion approved of such use.

The ethical issues at stake are incredibly broad, but one specific problem is that cognitive enhancers represent a case of technology outpacing science. Common though these drugs are, we still don’t fully understand how some of them work. Take methylphenidate, for example. At a basic level, we know that it interferes with protein pumps that import two signalling molecules – dopamine and norepinephrine – into neurons and as a result, these molecules build up in the spaces between neurons, the synapses. But why should such a build-up improve a person’s performance?

Nora Volkow, Director of the National Institute on Drug Abuse, thinks she has the answer. By studying the metabolic activity of brains dosed up with methylphenidate, she has found evidence that the drug works by focusing the brain’s activity and making it more efficient. And crucially, the benefits (and costs) you reap from that may depend on how focused your brain already is.

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Of the different types of flu virus, influenza A poses the greatest threat to human health and at any point in time, about 5-15% of the world’s entire population are infected with these strains. Together, they kill up to half a million people every year and the death toll rises sharply when pandemics sweep the globe.

Today, two papers published in Nature and Science shed new light on the origins of these epidemics. By prying into the private lives of flu viruses, the studies provide fresh clues about the birthplaces of new strains, their flight plans around the world and the locations of possible ‘viral graveyards’.

The findings could help health organisations to design better strategies for monitoring the emergence of new strains and selecting vaccines that will do the most good.

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Financial trading is really risky business for individuals and economies alike. Millions of pounds and dollars rest on the fast decisions of stressed people, working under extreme pressure. With such high stakes, it’s worth remembering that traders, regardless of their intellect or experience, are as fallible as the rest of us and their brains and bodies are influenced by the same ensemble of hormones.

Testosterone is one of these, and it’s of particular importance to traders for it can influence a person’s confidence and attitudes to risk during competitive encounters. While it seems almost clichéd to talk of the testosterone-fuelled alpha-male, a new study shows that traders that enter the floor with higher levels of this hormone do tend to make significantly higher profits over the course of the day. The actions of testosterone and other hormones could have large effects on entire markets by affecting the decisions of people in the financial sector.

John Coates and Joe Herbert from the University of Cambridge shadowed 17 male traders over 8 working days as they went about their business in a mid-sized City of London trading floor (the City is the capital’s financial district for the non-Brits among us). The bulk of their work took place between 11 am and 4pm, and at these times, Coates and Herbert took saliva samples to measure how their hormone levels shifted in a real-life situation. At the end of each one, the duo recorded how much profit and loss each trader had made.

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