- Dams Could Alter Local Weather, Cause More Rain
- Feeding Birds Could Create New Species
- Download Your Own Robot Scientist
- To Deflect an Asteroid, Try a Lasso, Not a Nuke
Posted: 03 Dec 2009 11:51 AM PST
As if America's aging dams were not in enough trouble already, new research suggests that their reservoirs could be increasing the intensity of extreme rainstorms in their immediate vicinities.
That's a problem because the dams were designed for the climate that existed in the area before they were built. If by virtue of their creation, they increase the chance that an extreme weather event will exceed the dams' capacity, they could be less safe than previously thought.
"What if the dam itself, its reservoir, could have accelerated or intensified the heavy rainfall patterns?" said Faisal Hossain, a hydrologist at Tennessee Tech University, who has co-authored a paper and editorial on the topic accepted for publication in Natural Hazards Review and Water Resources Research, respectively.
There is strong evidence that a standing body of water, like a lake, can alter precipitation patterns, Hossain said. Increasing the amount of liquid water in a region increases the amount of evaporation in a region, too. That water vapor will eventually condense and fall as precipitation. So, it's logical to think that a dam's reservoir could have the same impact. And dams allow irrigation, which can transform the land in the area, possibly leading to local climactic impacts.
Marshall Shepherd, a research meteorologist at the University of Georgia, called the findings "interesting and plausible" in an e-mail to Wired.com.
"The literature contains many examples of how extreme land use changes alter precipitation patterns," wrote Shepherd, whose own work focuses on climactic changes induced by cities.
Shepherd would like to see more detailed analysis of the mechanics behind how a dam could change local precipitation.
That kind of work could help explain why the changes Hossain and his collaborators have observed vary so much between sites. Some areas like southern Africa and Europe show as much as a 20 percent increase in extreme precipitation events after dams were built, but other areas, particularly in the United States, show just a percent or two increase.
Still, even a relatively small increase in the amount of precipitation could become a problem. As dams age, they lose some of their storage capacity as silt builds up along the reservoir bed, cutting the volume of water that physically fits in the reservoir. Hossain pointed to Lake Mead as an example, which he says has lost about 30 percent of its storage capacity.
Reservoirs with less room for precipitation are more susceptible to overflowing. One solution to the problem could be to decrease the amount of water in the reservoir to provide more space for rainwater.
"You can always lower the level of a reservoir to handle when that heavy cloudburst or flood happens," said Hossain.
But that could negatively impact dams' hydroelectric and irrigation capacity and may not be popular with the dam's users. Before such steps are taken, however, scientists will have to determine how much of problem the dam's alteration of local climate could be, Hossain admits.
Image: NASA/Lake Powell
Posted: 03 Dec 2009 11:00 AM PST
Something as simple as feeding birds can change their biological fate, and even seed the formation of a new species.
Central European blackcap warblers that spend the winter in the birdfeeder-rich United Kingdom are on a different evolutionary trajectory than those that migrate to Spain. The population hasn't yet split into two species, but it's headed in that direction.
"This is reproductive isolation, the first step of speciation," said Martin Schaefer, a University of Freiburg evolutionary biologist.
Blackcap migration routes are genetically determined, and the population studied by Schaefer has historically wintered in Spain. Those that flew north couldn't find food in barren winter landscapes, and perished. But during the last half-century, people in the U.K. put so much food out for birds that north-flying blackcaps could survive.
About 30 percent of blackcaps from southern Germany and Austria now migrate to the United Kingdom, shaving 360 miles from their traditional, 1,000-mile Mediterranean voyage. Because they've less distance to travel, they tend to arrive home first in the summertime and to live in prime forest-edge spots. All this makes the U.K. migrants more likely to mate with each other than with their old-fashioned brethren.
From these groupings, subtle differences are emerging. The U.K. birds tend to have rounded wings, which sacrifice long-distance flying power for increased maneuverability. Now that they don't need wide bills to eat Mediterranean olives in winter, their bills are becoming narrower and better-suited to summer insect diets. They're also slightly darker.
Schaefer thinks it unlikely that humans will keep feeding the blackcaps long enough for them to become truly separate species, but it's possible. He's now studying the fate of hybrid offspring born to British and Spanish migrants, that split the difference between their parents and winter in southwest France. If the hybrids have trouble surviving, the population will likely diverge even further, and now-subtle differences will become pronounced as blackcaps favor their closest kin.
Perhaps the most striking aspect of the findings, published Thursday in Current Biology, is the manner in which the populations diverged, said Schaefer. Reproductive isolation usually begins when a population is separated by a mountain or a sea, as with Darwin's famous Galapagos finches. "Here it's prompted by a very innocent human activity," said Schaefer.
1) A United Kingdom-migrating blackcap at left, and a Mediterranean-migrating blackcap at right./ Martin Schaefer. 2) Beat Walser.
Citation: "Contemporary Evolution of Reproductive Isolation and Phenotypic Divergence in Sympatry along a Migratory Divide." By Gregor Rolshausen, Gernot Segelbacher, Keith Hobson and H. Martin Schaefer. Current Biology, Vol. 19, No 23, Dec. 3, 2009.
Posted: 03 Dec 2009 10:35 AM PST
Ever wanted to have a robot to do your research for you? If you are a scientist, you have almost certainly had this dream. Now it's a real option: Eureqa, a program that distills scientific laws from raw data, is freely available to researchers.
The program was unveiled in April, when it used readouts of a double-pendulum to infer Newton's second law of motion and the law of conservation of momentum. It could be an invaluable tool for revealing other, more complicated laws that have eluded humans. And scientists have been clamoring to get their hands on it.
"We tend to think of science as finding equations, like E=MC2, that are simple and elegant. But maybe some theories are complicated, and we can only find the simple ones," said Hod Lipson of Cornell University's Computational Synthesis Lab. "Those are unreachable right now. But the algorithms we've developed could let us reach them."
Eureqa is descended from Lipson's work on self-contemplating robots that figure out how to repair themselves. The same algorithms that guide the robots' solution-finding computations have been customized for analyzing any type of data.
The program starts by searching within a dataset for numbers that seem connected to each other, then proposing a series of simple equations to describe the links. Those initial equations invariably fail, but some are slightly less wrong than others. The best are selected, tweaked, and again tested against the data. Eureqa repeats the cycle over and over, until it finds equations that work.
What took Newton years to calculate, Eureqa returned in a few hours on a decent desktop computer. Lipson and other researchers hope Eureqa can perform the same wizardry with data that now defies scientists, especially those working at the frontiers of biology, where genomes, proteins and cell signals have proven fantastically difficult to analyze. Their interactions appear to follow rules that traditional analytical methods can't easily reveal.
"There's a famous quote by Emerson Pugh: 'If the human brain were so simple that we could understand it, we would be so simple that we couldn't.' I think that applies to all of biology," said John Wikswo, a Vanderbilt University biophysicist who's using the Eureqa engine in his own lab. "Biology is complicated beyond belief, too complicated for people to comprehend the solutions to its complexity. And the solution to this problem is the Eureqa project."
Lipson made Eureqa available for download early in November, after being overwhelmed by requests from scientists who wanted him to analyze their data. In the meantime, he and Michael Schmidt, a Cornell University computational biologist responsible for much of Eureqa's programming, continue to develop it.
An ongoing challenge is the tendency of Eureqa to return equations that fit data, but refer to variables that are not yet understood. Lipson likened this to what would happen if time-traveling scientists presented the laws of energy conservation to medieval mathematicians.
"Algebra was known. You could plug in the variable, and it would work. But the concept of energy wasn't there. They didn't have the vocabulary to understand it," he said. "We've seen this in the lab. Eureqa finds a new relationship. It's predictive, it's elegant, it has to be true. But we have no idea what it means."
Lipson and Schmidt are now devising "algorithms to explain what our algorithm is finding," perhaps by relating unknown concepts to simpler, more familiar terms. "How do you explain something complicated to a child? That's what it involves," said Lipson. "It's machine teaching, rather than machine learning."
One set of incomprehensibly meaningful discoveries comes from Eureqa's analysis of cellular readouts gathered by Gurol Suel, a University of Texas Southwestern molecular microbiologist who studies how cells divide and grow. But even if Eureqa can't yet explain what it found, it's still useful, said Suel.
"You can use this as a starting point for further investigations. It lets you think about new ideas of what's going on in the cell, and generate new hypotheses about the properties of biological systems," said Suel.
Sometimes Eureqa will require more data than it's given before finding answers. In those cases, the program may be able to identify information gaps, and recommend experiments to fill them.
That functionality is included in the latest build of the program, and is being taken even further in a new Lipson-Wikswo project. They're hooking a version of Eureqa directly to Wikswo's experimental gadgetry.
"The program is going to adjust the valves, feeding different nutrients and toxins to the cells," and it does this faster than any researcher, said Wikswo. "It comes up with the equations, plus the experiments needed to come up with the equations. It's Eureqa on steroids."
According to Wikswo, who studies the effects of cocaine on white blood cells, Eureqa can propose experiments that researchers would have difficulty imagining.
"In most of science, you try to keep everything constant except for one variable. You turn one knob at a time, and see how the system responds. That's wonderful for linear systems," he said. "But most biology is complex and non-linear. Emergent behaviors are very hard to understand unless you turn many knobs at a time, and we can't figure out which knobs to turn. So we're going to let Eureqa pick them."
The Cornell team hasn't counted downloads of their program, but it's likely being used by researchers outside biology. As long as data fits on a spreadsheet, Eureqa can analyze it.
"In the past year, people have contacted us with some wild application ideas," said Schmidt. "Everything from predicting the stock market to modeling the herding of cows."
Images: 1) Hod Lipson running Eureqa in his office. 2) Diagrams of information flow through one of Lipson's self-repairing robots (left) and Eureqa (right).
Eureqa downloads and tutorials.
Posted: 03 Dec 2009 07:39 AM PST
To save the world from the real threat of a major asteroid impact, one engineer has imagined a scheme similar to George Bailey's wish to lasso the moon for his sweetheart in "It's a Wonderful Life."
The plan is to attach a gigantic weight to an Earth-bound asteroid using an enormous cord. This crazy-sounding contraption would change the asteroid's center of mass and subsequently its trajectory, averting a potentially catastrophic scenario.
Aerospace engineer Major David French of the Air Force Institute of Technology mathematically modeled how different weights and lengths of tether would affect a killer asteroid's orbit over time. The results are in the December issue of Acta Astronautica.
He found that, in general, longer tethers and larger masses would more significantly change the asteroid's orbit. The alteration would occur slowly, taking anywhere from 10 to 50 years.
The technique would require no simple mission. The cosmic counterweight would tip the scale at billions of pounds, while the rope would range anywhere from 6 miles (about the height of Mount Everest), to 60,000 miles (long enough to wrap around Earth two and a half times).
This solution may sound unrealistic, but the threat is real. To date, NASA's Near Earth Object Program, which tracks asteroids and comets that could approach the planet, has catalogued more than 5,500 objects. About 1,000 of these are classified as "potentially hazardous," meaning they could wipe out a city, spawn giant tsunamis, or in the worst case, eradicate life with a planet-shrouding cloud of debris.
To guard against this, scientists have produced many dramatic proposals, each with its own merits. French thinks his technique stands out for its relative ease.
"What interested me was that there is no active control system needed," he said. Once the rope and weight were installed, the asteroid would get nudged through nothing but the laws of gravity.
However, the method is not lacking critics.
"This tether deflection idea is an interesting intellectual exercise," said astronomer David Morrison of the Asteroid and Comet Impact Hazards Group at NASA's Ames Research Center. "But it is of no practical value."
Morrison points out that putting enormous objects, such as a heavy tether and ballast, in space is far beyond the entire human race's launch capability. Furthermore, the cost of designing and building a strong enough rope makes the solution intractable.
"From a practical point of view, the technique is a mess," agreed Russell Schweickart, former Apollo astronaut and co-founder of the B612 Foundation, a group dedicated to protecting the Earth from asteroid strikes. He is concerned that no one knows how to hook a tether to a spinning asteroid and, once attached, there is no guarantee the line won't get tangled up.
Schweickart and Morrison offer a much simpler idea that uses current technology: change the asteroid's orbit by crashing something into it. Even a relatively small satellite would alter the orbit enough to stave off certain doom, if we did it far enough in advance.
French understands these criticisms and thinks they are well founded. But, he said Earth will still need protection from asteroids in the next century, and the next millennium. If our technology and expertise isn't enough to lasso an asteroid right now, we have time.
"The last extinction-level asteroid strike was 65 million years ago," he said, "I think it's important to take the long view and maybe dig into technology that is not quite ready."
Image: Painting of the Chicxulub impact, 65 million years ago. Donald E. Davis/NASA/JPL.
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