Thursday, January 27, 2011

Reducing Test Anxiety

Some students get so anxious before tests that their test performance falls well below their abilities. The effect is usually greatest on high-stakes tests such as finals and standardized entrance exams. Why do such students “choke under pressure”?

According to current learning theory, anxious thoughts compete for space in the short-term working memory system. If the short-term memory system is concentrating on anxious thoughts, so the theory goes, it can’t focus as well on the information that might be most useful for the test.

If the current learning theory is true, then getting anxious thoughts out of one’s head before the exam might result in improved exam scores. Indeed, in a recent study, students who suffered from test anxiety had better final exam scores in high school biology when they sat down before the exam and wrote their anxious thoughts down, compared to students who didn’t write.

Just 10 minutes of writing was enough to raise the students’ final exam grades from a B- to a B+.

Sunday, January 23, 2011

Greenhouses in the Desert

The very real possibility of shortages of energy and freshwater some day are prompting the development of all sorts of innovative technologies, especially in the hottest, driest regions of the world. How about this - greenhouses in the desert that produce freshwater, powered only by the sun and using only saltwater drawn from the sea?

Here’s how it would work. Concentrated solar power would produce steam to drive turbines, producing electricity for power. Evaporation of saltwater would produce cool, moist air for the greenhouse. Hotter, more humid air leaving the greenhouse would be further heated and humidified using solar energy, then cooled (by cool seawater), producing freshwater by condensation. The freshwater would be used to irrigate crops both within and outside the greenhouse, and would support a local settlement. Presumably most of the saltwater (now saltier than before) would be returned to the sea.

An 8-acre pilot project is expected to begin operations in Jordan within five years. If it works, other larger projects may follow.

Wednesday, January 19, 2011

Transgenic Chickens Don't Transmit Bird Flu

By inserting a small piece of DNA into chickens that interferes with bird flu viral replication, scientists have developed transgenic chickens that don't transmit the bird flu virus to other chickens when they are infected with the virus. The inserted DNA fragment blocks a key enzyme required by the bird flu virus for replication of its RNA. Transgenic chickens exposed directly to the deadly H5N1 bird flu virus still get the flu and die, but they don’t pass it on to other birds in the flock. From an economic point of view, losing a few chickens is a lot less damaging than having to destroy a whole flock to try to prevent the spread of the disease. Flu-resistant transgenic chickens might also reduce the risk of a bird flu pandemic among humans some day.

Flocks of transgenic flu-resistant chickens could be widely available within a couple of years. That’s IF regulators decide that they and their eggs are safe to eat, and IF the public accepts them. Both are big “IF”s.

Monday, January 17, 2011

Climate Change Casualties

The evidence keeps getting stronger that climate change brought about by global warming is likely to cause disruptions in food production and mass migrations of some people from their homes and homelands within the next century. The latest article, in the January issue of Scientific American, describes three critical “hot spots” to watch – Mozambique, already experiencing more frequent droughts and floods; the Mekong Delta region of Vietnam, a rich farming area that is likely to face severe floods and loss of food production as the sea level rises; and Mexico and Central America, likely to be hit with increased numbers of tropical storms and crippling droughts.

Do we have the will to do something about climate change? Frankly, I’m not sure we do – the problem of global warming is still seen by many nations as either not severe enough, slow to develop, or not their fault (or at least not sufficiently their fault). Most nations have other more urgent issues to worry about first.

My prediction is that nations will spend more money over the next century dealing with the disastrous effects of climate change than they will in joining together to prevent the problems from ever happening in the first place. I sincerely hope I’m wrong.

But then, I won’t be here to see it, will I?

Tuesday, January 11, 2011

Eradicating a Disease

How hard is it to eradicate a disease from the planet completely? In all of history, that goal has been achieved only once – smallpox disease was eliminated finally in 1980. The smallpox virus now exists only as frozen samples in government laboratories in Russia and the U.S. It’s worth noting that it took 180 years to eradicate smallpox!

Other eradication programs, most notably one for malaria begun in 1955 and abandoned in the 1960s, have failed miserably. A few, like the ongoing $8 billion polio eradication program, have sharply reduced the economic burden and number of deaths from their respective diseases. But achieving complete eradication has proven elusive. A recent outbreak of polio in West Africa is one of the deadliest since the polio eradication program began 22 years ago.

It may be time to re-think whether eradication of any disease is a feasible goal. Perhaps containment and treatment make more sense. In all likelihood, future disease eradication proposals will be subject to careful cost-benefit analysis before they are launched.

Sunday, January 9, 2011

The "Not Tonight, Dear" Pheromone

An online report in Science last week demonstrates rather convincingly that women’s emotional tears contain an odorless chemical signal, or pheromone, that reduces sexual arousal in men. The press immediately dubbed it the “Not Tonight, Dear” pheromone, though that may be a bit simplistic.

Nevertheless, the evidence is clear; the men in the study rated pictures of women’s faces as less sexually attractive after sniffing tears collected from women who cried while watching sad films. They also exhibited progressive reductions in testosterone in their saliva, reductions in several psychophysiological measures of arousal, and even reductions in the activity of regions of the brain associated with sexual arousal compared to the control group. (In the control group, the same men sniffed plain saline that had been trickled down the cheeks of the women who had previously generated the tears.)

The identity of the chemical compound in women’s emotional tears is not yet known. Nor is it known whether the compound produces any other responses in men besides sexual disinterest, or whether men’s tears might also be sending some sort of signal to women.

For more on the subject of pheromones, see a previous blog post titled "Sensing Danger in the Air".

Wednesday, January 5, 2011

Eating While Distracted

We’ve all heard about driving while distracted is dangerous– are there any negative consequences to eating while distracted?

According to recent research, people who eat while playing computer games cannot remember what they ate as well as people who are not distracted when they eat. They also report that they feel less full after eating, and therefore they tend to eat more at the next meal.

The findings support the hypothesis that memory plays an important part in satiety. It’s tempting to speculate that a trend toward multitasking (including eating while working or playing games) may be contributing to the current obesity epidemic.