Archive for November 19th, 2011

November 19, 2011

Overactive Neurons May Tangle the Senses… But There’s More to It

Synesthesia is pretty interesting. In the most common form certain colors are perceived when particular associated letters or numerals are seen (even if they are not actually colored themselves). Other more unusual forms may (for example) associate colors with the performance of certain types of swimming strokes, or involve seeing two distinct colors at the same time.

When this happens, it’s as though some wires are crossed in the brain. Research just published suggests that an effect consistent with that idea and somewhat but not entirely like it is actually happening. It seems to occur in people in whom some of their perceptual neurons are too easily excitable. Consequently, higher levels in the perceptual system register more stimuli than are actually present, as the brain attempts to make sense of the inconsistent lower level data.

The research considered the commmon type of synesthesia – grapheme-color synesthesia – where colors are associated with particular letters and numbers.

Synaesthesia sends visual cortex crazy

Terhune and colleagues, stimulated the visual cortex of six grapheme-colour synaesthetes by applying a magnetic coil to the scalp to produce a weak magnetic field.

They found non-synaesthetes required three times greater magnetic stimulation to their visual cortex than synaesthetes in order to experience phosphenes, transient flashes of light or other visual disturbances.

Terhune says the study is the first to show that synaesthesia is linked to hyperexcitability in the area of the brain known as the visual cortex.

“One of the really interesting things about this study is the difference in the level of excitability [between synaesthetes and non-synaesthetes] is so great,” says Terhune.

But there must be more to synesthesia than hyperactive neurons.

read more »

November 19, 2011

Favored Higgs hiding spot remains after most complete search yet

Are we there yet? Well, no, not quite. Just be patient and try counting the cows, or something.

Despite a number of rumors and preliminary results, the Higgs boson hasn’t yet been found. There’s not even a clear signal yet that could be the real thing, with only a bit more data needed for better statistical confidence.

However, the possible range in energy space where the Higgs could hide keeps shrinking. The search parties are closing in. And it seems meaningful that so far everyone sees the same range where the Higgs might be.

Favored Higgs hiding spot remains after most complete search yet

The CMS and ATLAS experiments at the Large Hadron Collider have backed the Standard Model Higgs boson, if it exists, into a corner with their first combined Higgs search result.

The study, made public today, eliminates several hints the individual experiments saw in previous analyses but leaves in play the favored mass range for the Higgs boson, between 114 and 141 GeV. ATLAS and CMS ruled out at a 95 percent confidence level a Higgs boson with a mass between 141 and 476 GeV. …

“I think it could be an interesting message the data is telling us,” said physicist Eilam Gross of the Weizmann Institute of Science, who shares leadership of the ATLAS experiment’s Higgs group. “Any discovery starts with the inability to exclude.”

Several related measurements indirectly suggest a Standard Model Higgs boson exists at the lower end of the mass range.

It is possible, however, that some answer, based on data already collected, may come out before the end of the year.

Higgs hunt enters endgame

Analysis of the very latest data from this autumn — which Murray isn’t yet ready to share — will scour the range that remains. If it turns out to be empty, physicists may have to accept that the particle simply isn’t there. Working around the clock, the detector teams hope to have this larger data set analysed before the end of December. “We’ll know the outcome within weeks,” says Guido Tonelli, spokesman for the CMS detector.

November 19, 2011

Climate panel says prepare for weird weather

This certainly won’t change many skeptics’ minds… but for everyone else it further emphasizes the dangers (as if more were needed).

What mainly motivates the skeptics, it seems, is fears about the costs of reducing emissions of greenhouse gases, especially CO2. That will certainly entail costs, but even those are not easy to predict. Ironically, and unfortunately for the companies involved, the cost of photovoltaic energy has been plummeting, as the required materials (especially polysilicon) have become much cheaper. This, along with limitations on demand due to economic turbulence (especially in Europe), has put a number of solar companies out of business. But the trend is clear: photovoltaic energy, and other forms of solar energy, just keep getting more affordable. The exact opposite is true for fossil fuels, even without taking account of global warming and other externalities.

It’s not so hard to predict that there will be significant effects of accelerated global warming, but it’s harder to predict the timing and magnitude of the effects and their costs. Some costly effects seem pretty likely, such as extended periods of drought in many places, loss of habitable land, due to sea level rise, where many millions of people now live, poorer health and more deaths due to higher temperatures and severe shortages of food and potable water. And so forth.

And then there are the wildcards associated with extreme weather – severe flooding, more frequent and more intense hurricanes and tornadoes, forest fires resulting from prolonged heat waves.

Some of these extremes appear to be nearly certain, while others remain unpredictable possibilities. But even the possibilities, and their costs, need to be accounted for in terms of increased statistical expectation. You don’t know how much you’ll lose during a weekend at the Las Vegas casinos, but if you look at the odds (and the profits the casinos make), you can calculate the expected loss.

Climate panel says prepare for weird weather

Extreme weather, such as the 2010 Russian heat wave or the drought in the horn of Africa, will become more frequent and severe as the planet warms, the Intergovernmental Panel on Climate Change (IPCC) warns in a report released today. Some areas could become “increasingly marginal as places to live in”, the report concludes.

It is “virtually certain” — meaning 99–100% probability in IPCC terminology — that the twenty-first century will see an increase in the frequency and magnitude of warm temperature extremes and a decrease in cold extremes.

It is much less clear, however, how climate change will affect rainfall, flood risk and storminess.

And these weather events aren’t independent things either. Extremes in one part of the global weather system can lead to extremes in other parts. For example, the 2010 Russian heat wave and the severe flooding in Pakistan. (References: here, here)

It’s unfortunate that people don’t have too much trouble understanding the need to prepare for unpredictable events like earthquakes or even asteroid impacts – yet there’s so much reluctance to do anything about far more predictable outcomes associated with extreme weather.

Further reading:

Science panel: Get ready for extreme weather

IPCC Report: Global Warming—and Changing Population—Will Worsen the Toll of Extreme Weather

U.N. Panel Finds Climate Change Behind Some Extreme Weather Events

IPCC says it again – more confidently – expect extreme weather more often