Recipe for sand castles: 8 parts sand, 1 part water
Any child knows how hard it is to build a sand castle without water. But now, thanks to a team of local researchers, science is a step closer to knowing why. By observing piles of wet glass beads in a rotating drum, scientists at Clark University and MIT have developed a model that can predict the stability of a pile of granules by considering the geometry of the grains and the liquid bridges that form both at the surface and inside the pile. The research has practical implications, for instance, for civil engineers designing retaining walls to keep out floods.
BOTTOM LINE: The sturdiest sandcastles will be roughly eight parts sand; one part water.
CAUTIONS: Unlike the glass beads used in these experiments, natural grains may not be perfectly spherical. ''In a real pile, these things are not neatly arranged in pyramids like the ones we are considering," Arshad Kudrolli of Clark University, the study's lead author, said.
WHAT'S NEXT: In addition to investigating how well the model fits irregularly shaped or multi-sized grains, the researchers would like to know more about the physics of how a grain pile collapses.WHERE TO FIND IT: Nature Physics, October 2005
EMILY ANTHES
BIRTH DEFECTS
US losing ground against spina bifida
Despite a decade of public education campaigns, the percentage of young women who take a daily vitamin that could prevent serious birth defects is going down, according to a national survey released last week. Only one-third of women ages 18 to 45 said they take a daily vitamin containing folic acid, down from 40 percent in 2004, the March of Dimes survey found, usually because women said they ''forgot" to take the pills or believed they did not need them. Folic acid is crucial in early fetal development, and insufficient levels in a mother's bloodstream can lead to neural tube defects such as spina bifida, in which the spinal column doesn't close and the cord itself protrudes. The survey of 2,647 women carried out by The Gallup Organization and funded by the federal government found that the number of women who had heard of folic acid has reached an all-time high. However, only 7 percent of women said they knew that folic acid supplements are particularly important before a pregnancy.
BOTTOM LINE: The survey may show the limits of public education in changing health behavior, especially to prevent a relatively rare birth defect -- out of the 4 million live births in the United States each year, 3,000 babies suffered neural tube defects. However, if all women of child-bearing age took a daily vitamin containing 400 micrograms of folic acid, the number of defects would drop by 70 percent, March of Dimes officials said.
CAUTIONS: Even without vitamins, women can get the folic acid they need from eating dark leafy vegetables, legumes such as lentils or chickpeas and grain products such as bread, rice and cereal that have been enriched with folic acid. But most people don't get 400 micrograms a day from diet alone. It's almost impossible to overdose on folic acid because the body urinates it out.
WHAT'S NEXT: The March of Dimes wants the Food and Drug Administration to boost the required level of folic acid in enriched grain foods by 250 percent. The rate of neural tube defects dropped by one quarter after the FDA required some folic acids in grain products in 1998.
WHERE TO FIND IT: Morbidity and Mortality Weekly Report, Sept. 30, 2005
SCOTT ALLEN
INFLUENZA
Researchers recommend preschooler vaccinations
Flu shots are advised for all children between the ages of 6 months and 23 months. But there's no similar recommendation for 3- and 4-year-olds, and Boston researchers say there should be. By using data from a sophisticated disease tracking system, researchers at Children's Hospital Boston and Harvard Medical School discovered that 3- and 4-year-olds often spur flu outbreaks, showing up with the telltale respiratory symptoms of influenza weeks earlier than other children. ''Looking at those kids, it helps you predict what will happen in three weeks," said Dr. Kenneth Mandl, one of the study's authors. ''They're a window into the future and may help us prepare for things that are unexpected."
BOTTOM LINE: Researchers believe preschoolers should be routinely vaccinated against the flu to avoid spreading it to other children and adults.
CAUTIONS: Children who are 3 to 4 years old are not at heightened risk of complications from flu, so vaccination would primarily help others, not themselves. The flu vaccine carries very little risk for anyone who is not allergic to eggs.
WHAT'S NEXT: One of the Boston researchers, John Brownstein of Children's, said disease surveillance systems should be refined to more closely track flu in 3- and 4-year-old children and its spread.
WHERE TO FIND IT: American Journal of Epidemiology, Oct. 1, 2005
STEPHEN SMITH
LUNG CANCER
Connection between disease and vegetables explored
In the continuing search for foods that can reduce cancer risk, doctors at the University of Texas M.D. Anderson Cancer Center decided to explore whether a diet rich in vegetables might cut the risk for lung cancer. The researchers had previously found that women taking estrogen as part of hormone replacement therapy had a reduced risk of developing lung cancer. They wondered whether dietary phytoestrogen, found in soy products, tea and coffee, broccoli, and other vegetables, would have similar effects. They asked more than 1,700 patients with lung cancer and more than 1,600 healthy individuals to report on their eating habits for the previous year. The researchers calculated their intake of three different classes of phytoestrogen -- isoflavones found in soy, lignans found in rye grains and tea, and cumestrans found in beans and spinach. The people with lung cancer were significantly less likely to have eaten foods rich in phytoestrogens than those without cancer. The protective effect of phytoestrogen was highest in people who had never smoked.
BOTTOM LINE: A diet rich in fruits, grains, and vegetables may help fight lung cancer. ''What our mothers have been saying for years is absolutely right," said Matthew Schabath, the study's lead author. ''Eating a large variety of fruits and vegetables wards off disease." But if you smoke, quitting is still the best way to reduce lung cancer risk, he said.
CAUTIONS: Fruits and vegetables contain large numbers of nutrients, so the beneficial effect the study detected may be due to other nutrients or lifestyle habits. In addition, the researchers asked people to recall their diets from years prior -- a hard thing to do accurately after so much time has elapsed. Such look-back studies cannot prove a link between a nutrient and disease prevention.
WHAT'S NEXT: Dr. Schabath and his colleagues are searching for variations in genes that make certain individuals more susceptible to cancer.
WHERE TO FIND IT: Journal of the American Medical Association, Sept. 28, 2005
ALISON Z. YANG
INSECTS
For some bugs, walking on water has ups and downs
To the human eye, lakes and ponds may appear smooth as glass. But from an insect's point of view, the water's surface is a rough landscape of slippery slopes -- a topography water-walking insects must maneuver to reach land. Until now, just how these insects navigate this perilous path has been a mystery. Using high-speed video, scientists at MIT have captured the movements of three water-walking bugs as they scale these insect-sized mountains, called menisci, which occur where water meets a solid substance such as land or floating vegetation. The three species in this study adopt unusual postures -- for example, ''grabbing" and forming tiny peaks in the water's surface with specialized claws -- that create forces that propel the insects up and over at lightning speed, about 30 body lengths per second -- and all without moving their legs. Water-walkers use the technique to reach land to lay eggs or escape predators.
BOTTOM LINE: ''When engineers think about designing small, submersible, water-repellent structures, there will be much to be learned from" these water-walking insects, said John Bush, an associate professor of mathematics and co-author of the study.
CAUTIONS: Scientists were unable to determine exactly how the insects use their special claws to grasp and lift the water's surface.
WHAT'S NEXT: The researchers plan to further study the fine, water-repellent hair coating on the insects' exterior to see how it impacts the bugs' movement.
WHERE TO FIND IT: Nature, Sept. 29, 2005
KELLI WHITLOCK BURTON 
