Scientific American - Math

DNA Sudoku

Wed, 01 Jul 2009 17:30:00 EST

A 2,000-year-old math theorem, along with Sudoku, may soon help researchers untangle DNA at blazing speeds. [More]

Grassoline: Biofuels beyond Corn

Mon, 29 Jun 2009 08:00:00 EST

By now it ought to be clear that the U.S. must get off oil. We can no longer afford the dangers that our dependence on petroleum poses for our national security, our economic security or our environmental security. Yet civilization is not about to stop moving, and so we must invent a new way to power the world’s transportation fleet. Cellulosic biofuels--liquid fuels made from inedible parts of plants--offer the most environmentally attractive and technologically feasible near-term alternative to oil.

Biofuels can be made from anything that is, or ever was, a plant. First-generation biofuels derive from edible biomass, primarily corn and soybeans (in the U.S.) and sugarcane (in Brazil). They are the low-hanging fruits in a forest of possible biofuels, given that the technology to convert these feedstocks into fuels already exists (180 refineries currently process corn into ethanol in the U.S.). Yet first-generation biofuels are not a long-term solution. There is simply not enough available farmland to provide more than about 10 percent of developed countries’ liquid-fuel needs with first-generation biofuels. The additional crop demand raises the price of animal feed and thus makes some food items more expensive--though not nearly as much as the media hysteria last year would indicate. And once the total emissions of growing, harvesting and processing corn are factored into the ledger, it becomes clear that first-generation biofuels are not as environmentally friendly as we would like them to be.

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The Science of Economic Bubbles and Busts

Mon, 22 Jun 2009 08:00:00 EST

It has all the makings of a classic B movie scene. A gunman puts a pistol to the victim’s forehead, and the screen fades to black before a loud bang is heard. A forensic specialist who traces the bullet’s trajectory would see it traversing the brain’s prefrontal cortex--a central site for processing decisions. The few survivors of usually fatal injuries to this brain region should not be surprised to find their personalities dramatically altered. In one of the most cited case histories in all of neurology, Phineas Gage, a 19th-century railroad worker, had his prefrontal cortex penetrated by an iron rod; he lived to tell the tale but could no longer make sensible decisions. Cocaine addicts may actually self-inflict similar damage. The resulting dysfunction may cause even abstaining addicts to crave the drug any time, say, the thudding bass of a techno tune reminds them of when they were stoned.

Even people who do not use illicit drugs or get shot in the head have to contend with the [More]

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Why Aren't More Women Tenured Science Professors?

Fri, 19 Jun 2009 17:55:00 EST

Women who apply for tenure-track positions at top-tier research universities in math and sciences these days have a slightly better chance of landing the job than their male colleagues, says a new study funded by the National Science Foundation. [More]

Stimulus Funds for Science Raise Concern about Misconduct

Fri, 19 Jun 2009 08:00:00 EST

One unintended side effect of Congress’s intense efforts to jump-start the U.S. economy is the threat of fraud. Earl Devaney, chair of a newly appointed federal watchdog agency, the Recovery Accountability and Transparency Board, has warned that without precautionary measures, as much as 7 percent of the stimulus package will end up in the hands of bad actors. Apply Devaney’s math to the $31 billion being spent on science--by the National Institutes of Health, NASA, the Departments of Commerce and Energy, and the National Science Foundation (NSF) combined--and stimulus funds represent an unprecedented boost not only for science, but also, potentially, for science fraud.

Under the stimulus bill, formally known as the American Recovery and Reinvestment Act, various science-funding agencies will enjoy a substantial uptick in their budgets. But they are under pressure to dole out the new funds quickly on “beaker ready” projects. The risk of scientific misconduct has generally been considered to be less than 1 percent, but the size of the disbursements and the added reporting requirements (namely, quarterly status reports and updates on job creation) could tempt researchers to cut corners or even fake aspects of applications. Meanwhile at the agencies, the urgency to spend could take precedence over monitoring. “We’re not going to know until it happens. It probably is occurring,” concedes Patricia Dalton of the Government Accountability Office.

[More]

Puzzling Adventures: The Fair Way to Get a College Scholarship: Let's Make a Deal

Fri, 12 Jun 2009 12:00:00 EST

One hundred students are competing for college scholarships. They come from 10 schools (10 students per school). From each school, one student has declared physics as a major; one has declared chemistry; one, biology; one, psychology; one, mathematics; one, economics; one, anthropology; one, linguistics; one, English; and one, history. So, the group has 10 students for each of these majors. [More]

News Scan Briefs: Hand Transplant Recipients Switch Handedness

Fri, 12 Jun 2009 09:00:00 EST

On the Other HandDouble-hand transplantations could switch the handedness of patients. Two men who lost both hands in work injuries received transplants after three to four years of waiting. Despite such a long time--the brain typically reassigns areas linked with control of the amputated limb to other muscles--researchers at the French Center for Cognitive Neuroscience in Lyon found the patients’ brain could connect to the new hands, which subsequently could perform complex tasks (in a demonstration, one patient repaired electrical wires). Although both men were right-handed, their left hand connected with their brain at least a year sooner than their right hand did, and they stayed left-handed. The reason for this switch, reported online April 6 by the Proceedings of the National Academy of Sciences USA, is unclear--perhaps the prior dominance of the right hand made the corresponding brain regions less flexible to reconnections or the surgeries were done slightly differently. --Charles Q. Choi

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Population and Sustainability: Can We Avoid Limiting the Number of People?

Wed, 10 Jun 2009 11:01:00 EST

In an era of changing climate and sinking economies, Malthusian limits to growth are back--and squeezing us painfully. Whereas more people once meant more ingenuity, more talent and more innovation, today it just seems to mean less for each. Less water for every cattle herder in the Horn of Africa. (The United Nations projects there will be more than four billion people living in nations defined as water-scarce or water-stressed by 2050, up from half a billion in 1995.) Less land for every farmer already tilling slopes so steep they risk killing themselves by falling off their fields. (At a bit less than six tenths of an acre, global per capita cropland today is little more than half of what it was in 1961, and more than 900 million people are hungry.) Less capacity in the atmosphere to accept the heat-trapping gases that could fry the planet for centuries to come. Scarcer and higher-priced energy and food. And if the world’s economy does not bounce back to its glory days, less credit and fewer jobs.

It’s not surprising that this kind of predicament brings back an old sore topic: human population and whether to do anything about it. Let’s concede up front that nothing short of a catastrophic population crash (think of the film Children of Men, set in a world without children) would make much difference to climate change, water scarcity or land shortages over the next decade or so. There are 6.8 billion of us today, and more are on the way. To make a dent in these problems in the short term without throwing anyone overboard, we will need to radically reduce individuals’ footprint on the environment through improvements in technology and possibly wrenching changes in lifestyle.

[More]

Bold Strokes Needed Now to Save Climate

Wed, 10 Jun 2009 11:00:00 EST

The climate challenge just became a lot more challenging. We know that man-made carbon dioxide emissions are accelerating global warming. But intrepid research has revealed an additional sinister threat: methane. As Sarah Simpson reports, the warming of the Arctic is releasing vast quantities of methane that has been locked away for centuries in formerly frozen soil. Once released, methane traps 25 times more heat in the atmosphere than carbon dioxide does. So it is more imperative than ever to slash greenhouse gases quickly, to slow the venting of methane.

The single boldest stroke must come from Congress. The House and Senate are debating legislation that would impose either a cap-and-trade system or a tax on carbon emissions (for updates see www.ScientificAmerican.com/Earth3). Certain politicians and CEOs are trying to talk Congress out of it. Our representatives should dismiss the detractors and pass legislation, before November. That deadline is crucial: nations will meet in December in Copenhagen to hammer out new international agreements to limit emissions. The U.S., shamefully, has never signed such a protocol, and leaders worldwide have said, plainly, that the Copenhagen talks will fail if the U.S. does not enact legislation to clean up its own backyard.

[More]

Genetic Copy Variations and Disease

Fri, 05 Jun 2009 08:00:00 EST

Scientists published the first draft of the human genome nearly a decade ago, but the hunt for disease genes is far from over. Most researchers have focused on single changes in DNA base pairs (AT and CG) that cause fatal diseases, such as cystic fibrosis. Such mutations among the genome’s three billion base pairs don’t tell the whole story, however. Recently geneticists have taken a closer look at a genetic aberration previously considered rare: copy number variation (CNV). The genes may be perfectly normal, yet there is a shortage or surplus of DNA sequences that may play a role in diseases that defy straightforward genetic patterns, such as autism, schizophrenia and Crohn’s disease, the causes of which have stumped researchers for decades.

American geneticist Calvin Bridges discovered copy number variation in 1936, when he noticed that flies that inherit a duplicate copy of a gene called Bar develop very small eyes. Two decades later a French researcher studying human chromosomes under a microscope identified CNV as the cause of Down syndrome: sufferers inherit an extra copy of chromosome 21. By all appearances, CNV was rare and always a direct cause of disease.

[More]

Exotic Quasicrystal May Represent New Type of Mineral

Thu, 04 Jun 2009 16:00:00 EST

A team of researchers says it has found in a Russian mineral sample the first natural example of a quasicrystal, an unusual material that displays some of the properties of a crystal but boasts a more intricate and complex structure. Since quasicrystals were characterized 25 years ago, numerous versions have been cooked up in the laboratory, but a natural example would indicate that nature's products are more diverse than previously thought. [More]

Does who scores the first goal determine who wins a hockey game?

Tue, 02 Jun 2009 20:52:00 EST

When Pittsburgh Penguins center Evgeni Malkin hit a snap shot past Detroit Red Wings goalie, Chris Osgood, just under 17 minutes into Game Two of the National Hockey League’s Stanley Cup Finals on Sunday, Pittsburgh fans probably grew optimistic. Their team had scored first, seeming to make a victory much more likely. [More]

Joe Buff: A Lifelong Interest in the Navy Comes Full Circle

Tue, 02 Jun 2009 15:30:00 EST

His finalist year: 1970 [More]

Tetris marks 25 years of haunting gamers' dreams

Tue, 02 Jun 2009 14:48:00 EST

Tetris, one of the most renowned and addictive creations in the brief history of video games, turns 25 this week. [More]

Cash for Clunkers: A Fair Trade for the Environment

Tue, 02 Jun 2009 11:00:00 EST

Old cars that foul the air with dirty exhaust are a valuable commodity in Texas. If you own a clunker at least 10 years old and live near a major city like Houston, the state will give you a voucher worth more than the car’s value. Drive the car to a dealer, sign a few forms, hand over the voucher--worth up to $3,500--and drive off in a newer vehicle, no soot trailing you down the road.

For the clunker, this swap is the last stop before being plundered for parts and scrap metal. But for low- and middle-income consumers, it’s an opportunity to trade up to a newer car they might not otherwise have been able to afford--a cleaner car that is also cheaper to operate because, being much newer, it gets better gas mileage--further benefiting the environment. Texas sent 13,492 jalopies to the scrap heap during the last year in a program financed by auto inspection fees and designed to help the state’s urban areas meet clean air standards. California is trying a scrappage program, too, as are Canada and various European countries.

[More]

What Conficker Reveals about Internet Crime

Tue, 26 May 2009 08:00:00 EST

Computer users could be forgiven if they kept their machines off on April 1. Since it first appeared last November, the malicious software known as the Conficker worm has established itself as one of the most powerful threats the Internet has seen in years, infecting an estimated 10 million computers worldwide. The malware slipped into machines running the Windows operating system and waited quietly for April Fools’ Day (the timing did not go unnoticed), when it was scheduled to download and execute a new set of instructions. Although no one knew what was to come, the worm’s sophistication provided a stark example of how the global malware industry is evolving into a model of corporate efficiency. At the same time, it raised calls for security researchers to steal a trick from their black hat counterparts.

A worm takes advantage of security holes in ubiquitous software--in this case, Microsoft Windows--to spread copies of itself. Conficker, though, was a strikingly advanced piece of code, capable of neutering a computer’s antivirus software and receiving updates that would give it more complex abilities. Its sudden march across the Web reignited interest in one of the most controversial ideas in security protection: the release of a “good” worm. Such software would spread like a worm but help to secure the machines it infected. The approach had already been attempted once before. In late 2003 the Waledac worm burrowed into Windows machines by exploiting the same vulnerability as the then widespread Blaster worm. Yet unlike Blaster, which was programmed to launch an attack against a Microsoft Web site, Waledac updated the infected machines with security patches.

[More]

Rethinking the Global Money Supply

Thu, 21 May 2009 08:00:00 EST

The People’s Bank of China jolted the financial world in March with a proposal for a new global monetary arrangement. The proposal initially attracted attention mostly for its signal of China’s rising global economic power, but its content also has much to commend it.

A century ago almost all the world’s currencies were linked to gold and most of the rest to silver. Currencies were readily interchangeable, gold anchored exchange rates and the physical supply of gold stabilized the money supply over the long term.

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Puzzling Adventures: You've heard of Sudoku. But what about Sudokill?

Wed, 13 May 2009 11:00:00 EST

I suspect that among the readers of this column, few are unfamiliar with Sudoku. The same cannot be said about Sudokill, a game invented for a graduate class I teach. Sukokill is a two-person game in which players try to force each other to violate the Sudoku rules. [More]

Math: The Eyes Have It

Mon, 11 May 2009 08:35:08 EST

[The following is an exact transcript of this podcast.]

I still tend to move my fingers, almost subconsciously, when doing arithmetic. Well, that might not be so strange, according to research published in the May 8th issue of the journal Science. The report says that math and movement through space use some of the same brain circuitry.

[More]

Figuring Out Movies You'd Really Like

Wed, 29 Apr 2009 09:57:08 EST

[The following is an exact transcript of this podcast.]

Netflix isn’t satisfied with the way its system recommends new movies to customers based on their viewing habits. So the mail-order DVD rental company has offered outside teams prizes to improve its accuracy. A group from AT&T Laboratories has already won $50,000 for figuring out a formula that’s 8.43 percent better at telling a film buff what to rent. And Netflix is sweetening the pot--the team that can improve recommendation accuracy by 10 percent will get a cool million. [More]