What makes the unique sound of a Stradivarius violin?
The wood, of course. Using x-ray images taken from multiple different angles, radiologist Berend Stoel of Leiden University Medical Center in the Netherlands proved that the spruce and maple wood used in five violins made either by Antonio Stradivari or Giuseppe Guarneri del Gesù—the rival master luthiers of Cremona—had fewer variations in their density than that in seven contemporary violins. The density of the wood determines how a violin resonates with sound, which may explain why Stradivarius and Guarnerius violins are coveted by musicians worldwide and fetch prices of several million dollars. It may also allow modern instrument makers to finally match the perfection of past masters.

Who's happy? You are

Believe it or not, the world is becoming a happier place, at least according to the University of Michigan Institute for Social Research's 2005 to 2007 World Values Survey. The cheeriest country?: Denmark. The gloomiest: Zimbabwe—no surprise given the political unrest there. The U.S. ranks 16th on the list, just after New Zealand. According to the research, published in the journal Perspectives on Psychological Science, people are happiest in countries with the most tolerant social norms and most democratic political systems: Iceland, Switzerland, the Netherlands and Canada all rank among the top 10 happiest countries in the world. Researchers have surveyed more than 350,000 people on how happy they have been for the past 26 years based on their responses to the same two questions: "Taking all things together, would you say you are very happy, rather happy, not very happy, not at all happy?" As well as, "All things considered, how satisfied are you with your life as a whole these days?" Democratization and rising social tolerance have even more of an impact than economic growth on happiness, although all are important contributors. The citizens of India, Ireland, Mexico, Puerto Rico and South Korea all indicate that they're becoming happier. Alas, those in Austria, Belgium, the U.K. and Germany say their joie de vivre is waning.

High-res x-rays improve food inspections

Until recently, food inspectors have mostly used high-energy systems similar to those used to scan luggage at airports to carefully examine food. The problem: these are able to detect, say, a pebble in a package of corn but they lack the resolution to pick out a grain of sand in a bag of flour. But the European Union–funded MODULINSPEX project may have the answer. In a quest to make sure that food is all that's in our dinner, researchers there have developed low-energy x-ray detection and sorting systems that create highly detailed images of food products and packaged goods. The system can be used to check seals on food wrappers, locate packaging defects, and find foreign particles of any size in any kind of food, from maggots in apples to grains of sand in bread. The use of low-energy x-rays had previously been too slow for food inspectors to use because it took too long for them to get high-resolution images. By attaching a computer chip to the crystal that detects the x-rays in a low-energy system, MODULINSPEX researchers built a detector capable of taking 300 images per second, enough to capture a detailed image of products moving on a conveyor belt at 1.6 feet (0.5 meter) per second. These low-energy x-ray images have a resolution of 0.004 inch (0.1 millimeter, or 16 times better than existing high-energy systems), making it possible to detect objects as small and fine as a herring bone. The consortium of companies involved in the MODULINSPEX project has already sold three of their systems to companies in Spain, the U.K. and Denmark since November.

GLAST Gamma-Ray Satellite Powered up
Less than a month after entering orbit, NASA's Gamma-ray Large Area Space Telescope (GLAST) is powered up and ready to go. Project scientists at the Stanford Linear Accelerator Center in California have begun receiving data from the satellite's Large Area Telescope, one of two instruments it will use to scan the sky for energetic gamma rays, the space agency reported today. Launched on June 11, GLAST is designed to study galactic powerhouses including black holes, pulsars and gamma-ray bursts and could potentially detect dark matter as well. Researchers plan to spend the next two months calibrating the instruments to make sure they know what they're seeing as the data starts rolling in.

Lizards grow up so fast these days
A new chameleon species has what may be the briefest, oddest life cycle of any four-legged animal. Researchers were puzzled to find during repeated trips to southwestern Madagascar, home to Labord's chameleon (Furcifer labordi), that the lizards quickly went from adulthood to dead, with no juveniles or other stragglers. After studying about 400 of the critters, they pieced together the life cycle: The chameleons reproduce in January and February; the offspring hatch simultaneously in November and begin a mad dash to sexual maturity, growing up to 0.1 inch (2.6 millimeters) daily. After 60 days, males have tripled or quadrupled in body size and are ready to breed. All told, the lizards live for a mere four to five months after hatching. Tetrapods (four-legged animals), including mammals, birds, lizards and amphibians, typically live two to 10 years—with notable exceptions, such as long-lived humans and turtles. Researchers report in Proceedings of the National Academy of Sciences USA that this may explain why some chameleons die so rapidly in captivity.

The latest buzz on the West Nile Virus
The season's first cases of the West Nile Virus have been reported the past few weeks in places like Colorado and Pennsylvania. But lest you worry too much, take note: The U.S. Centers for Disease Control (CDC) says the virus, transmitted by infected mosquitoes, is harmless to most people and that 80 percent who have it show no symptoms. The most vulnerable are infants, young children, the elderly and those with compromised immune systems. The CDC says that about one in 150 people stricken with the infection develop serious symptoms, which may include high fever, nausea, convulsions and temporary paralysis. Although it rarely is fatal, seven out of the 576 people in Colorado confirmed to have the disease died last year, for example. Birds, especially crows and robins, are known to harbor the virus, and mosquitoes become carriers when they feast on their carcasses. Worried? Then you might want to toss some insect repellent in your beach bag.