| Science news |
[Aug. 6th, 2003|12:51 pm] |
Musical roots may lie in human voice
Key universal features in world music may have their roots in the ever-present sound of the human voice during the course of evolution, suggests a new study.
The analysis of thousands of recorded speech samples found peaks in acoustic energy that precisely mirror the distances between important notes in the twelve-tone scale, the system that forms the foundation of almost all music.
Different musical traditions have characteristic sound because many cultures have devised scales from a subset of the full chromatic scale, with different distances, or "intervals," between the tones. Chinese music is based on five-tone scales, while scales common in Western music have seven tones.
But all cultures favour certain intervals from the chromatic scale, and listeners judge these same intervals to create the most harmonious combinations of two tones. Pythagoras proposed that such preferences could be predicted from mathematical relationships between tones, but these approaches have yet to provide a complete explanation.
The Duke researchers randomly extracted over 100,000 speech samples, each 0.1 second long, from recordings of thousands of English sentences. Acoustic analysis of the combined samples revealed 10 frequency peaks that match the most significant intervals used in musical scales worldwide.
Science graduates live long and prosper
Science and medicine students go on to live longer and healthier lives than those studying other subjects, according to a survey of men attending university between 1948 and 1968.
Peter McCarron, at Queens University Belfast, Northern Ireland, and colleagues examined the medical records of nearly 10,000 male graduates of Glasgow University. The researchers found that science, engineering and medical students had a substantially lower risk of mortality than arts students.
However, medical students went on to have the largest number of alcohol-related deaths and death from suicide or violent means. They were also the heaviest smokers as students, followed by lawyers.
Nonetheless, arts students had greatest risk of contracting lung cancer or a cardiovascular disease. "We speculate that medics changed their social habits after leaving university," McCarron told New Scientist. "They would have had access to the studies which came out around that time and probably realised the benefits of giving up."
You are what your mother ate, suggests study
What mothers eat during pregancy could have a fundamental and lifelong effect on the genes of their children, suggests an intriguing new study in mice.
Researchers found they could change the coat colour of baby mice by feeding their mothers different levels of four common nutrients during pregnancy. These altered how the pups' cells read their genes. As a result the mice were also less prone to obesity and diabetes than genetically identical mice whose mothers received no supplement.
The work establishes the tightest link yet between diet and a strange form of inheritance known as epigenetics. Unlike a mutation which changes the DNA sequence of genes, epigenetic factors can alter how a gene is used, while leaving the DNA sequence unchanged.
One suggested mechanism for epigenetic inheritance is via methylation. A gene can be switched on or off by the adding or removing of carbon tags known as methyl groups to the DNA near a gene.
These are generally set as part of the normal genetic program. But experiments in mice have shown that the tags can be reset by a variety of factors including viral infection or ingestion of certain drugs. Once these new methylation marks are established, they can be inherited by future generations.
Animation lets murder victims have final say
Forensic reconstructions of dead people's faces from skeletal remains are about to become much faster and more lifelike. A novel 3D graphics program not only speeds up the laborious process of recreating a face from a skull, but also allows the dead to frown or smile realistically.
Today, when the police find a skeleton or skull, they turn to forensic artists to build a model of what the dead person might have looked like. The artist makes a plaster cast of the skull and covers it with clay to mimic flesh. The thickness of the original flesh is estimated from standard tables called tissue depth charts.
Now Kolja Kähler and Jörg Haber of the Max Planck Institute for Computer Science in Saarbrücken, Germany, and their colleagues have developed software that can rapidly reconstruct a face and give it some personality.
They first scan a skull to create a 3D computer model of it. Next, they identify sites on the skull for which tissue depths are available. The software model then automatically adds flesh of appropriate thickness to the skull, suitably adjusted for variables such as ethnicity and sex (see graphic).
The tricky part is to animate the reconstructed face realistically. For this, the researchers have built a generic virtual head that is animated to simulate the 24 facial muscles responsible for our expressions.
The features of the reconstructed skull, such as skull shape and tissue depth, are used to customise the reference animated head. The result is a fully animated head that can adapt its expression in the same way as the dead person might have.
"We can show subtle facial expressions, and that's something that the traditional clay sculpting method cannot do," says Haber. For instance, creating a friendly or angry face with traditional methods would mean going back to the sculpting table. "With our system, it's just a few clicks of the mouse, and you can change the expression."
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