Why do the violins made by Stradivari and Guarneri del Gesù sound so good? Countless theories have been proposed for the secret of these eighteenth-century Italian instrument-makers, but attempts to identify a unique acoustic signature have proved fruitless. Now a study has finally identified a measurable sound quality that distinguishes these old violins from cheap, factory-made instruments.
After spending ten years painstakingly measuring the acoustics of violins rated from "bad" to "excellent" by professional musicians, George Bissinger of East Carolina University in Greenville, North Carolina, says that the 'excellent' old Italian violins in his sample show a significantly stronger acoustic response in the lower octaves than do the 'bad' violins, whereas those rated merely 'good' have intermediate values1. The high-quality tone is caused by a single mode of vibration of air inside the body, which radiates sound strongly through the violin's f-holes.
Science & Technology
This weird-looking image
is the sharpest picture of Jupiter ever taken from the ground. Taken with a device called - are you ready for this? - the Multi-Conjugate Adaptive Optics Demonstrator (or MAD, in an acronymic stretch), it has a resolution better than Hubble's!
The Earth's atmosphere roils and waves, distorting ground-based views of the sky. That's one of the reasons we launch telescopes into space, to get above all that mess. But if you can observe a point-like object such as a star at the same time you observe your target object, it's possible to compensate for the distortion by taking extremely rapid fire snapshots and measuring the way the star image changes. You then apply a correction to the image, and presto! It's cleaner. However, you can only do this for the area near the star. Distortions change across a telescope's field of view, making this technique somewhat limited.
© Discover Magazine
Jupiter, looking sharp and hot
Jupiter, looking sharp and hot
The Earth's atmosphere roils and waves, distorting ground-based views of the sky. That's one of the reasons we launch telescopes into space, to get above all that mess. But if you can observe a point-like object such as a star at the same time you observe your target object, it's possible to compensate for the distortion by taking extremely rapid fire snapshots and measuring the way the star image changes. You then apply a correction to the image, and presto! It's cleaner. However, you can only do this for the area near the star. Distortions change across a telescope's field of view, making this technique somewhat limited.
The Australian government has issued its first license allowing scientists to create cloned human embryos to try and obtain embryonic stem cells.
DRUIDS, mystics, UFO enthusiasts and even the occasional rock star have converged in awe beneath its arcane structure.
Now, after its eternal mysteries have driven generations of archaeologists round in circles, a lucid new theory has suggested Stonehenge was conceived for a more prosaic purpose - as a Neolithic health centre.
The latest hypothesis surrounding one of the world's best known but least understood landmarks suggests the world heritage site was a precursor to Lourdes.
The claim follows the first dig inside Stonehenge's concentric circles for nearly half a century. The excavation this spring unearthed many fragments of bluestone, accorded healing powers in medieval folklore and literature, and seemingly taken as lucky charms by visitors to Salisbury Plain.
Now, after its eternal mysteries have driven generations of archaeologists round in circles, a lucid new theory has suggested Stonehenge was conceived for a more prosaic purpose - as a Neolithic health centre.
The latest hypothesis surrounding one of the world's best known but least understood landmarks suggests the world heritage site was a precursor to Lourdes.
The claim follows the first dig inside Stonehenge's concentric circles for nearly half a century. The excavation this spring unearthed many fragments of bluestone, accorded healing powers in medieval folklore and literature, and seemingly taken as lucky charms by visitors to Salisbury Plain.
NASA's Messenger spacecraft will zip past the surface of Mercury on Monday, allowing it to glimpse a third of the planet that has not yet been seen close up.
The flyby will take the car-sized probe within 200 kilometres of the surface, at a speed of more than 24,000 km per hour.
This is the probe's second close look at the scarred, rocky planet. During a flyby on 14 January, Messenger captured detailed images of a previously unseen 20% of the planet's surface.
Monday's flyby will produce more than 1200 images - the first of which will be transmitted back to Earth on Tuesday - to cover an additional 30% of the surface.
© NASA/JHU APL/CIW
Buff-coloured volcanic plains in Mercury's huge Caloris impact basin are shown in this mosaic of images taken during Messenger's first flyby on 14 January. As much as 95% of Mercury's surface will be mapped after Messenger's second flyby on 6 October, allowing researchers to estimate for the first time what fraction of the surface is covered by volcanic lava flows.
Buff-coloured volcanic plains in Mercury's huge Caloris impact basin are shown in this mosaic of images taken during Messenger's first flyby on 14 January. As much as 95% of Mercury's surface will be mapped after Messenger's second flyby on 6 October, allowing researchers to estimate for the first time what fraction of the surface is covered by volcanic lava flows.
The flyby will take the car-sized probe within 200 kilometres of the surface, at a speed of more than 24,000 km per hour.
This is the probe's second close look at the scarred, rocky planet. During a flyby on 14 January, Messenger captured detailed images of a previously unseen 20% of the planet's surface.
Monday's flyby will produce more than 1200 images - the first of which will be transmitted back to Earth on Tuesday - to cover an additional 30% of the surface.
They may not have used clubs, but Neanderthals hunted seals too. Anthropologists have discovered ancient seal bones showing signs of butchery, as well as some dolphin remains, in two caves in Gibraltar.
The discovery bolsters the image of Neanderthals as intelligent and adaptable hunters, rather than knuckle-dragging brutes, says Clive Finlayson of the Gibraltar Museum.
Finlayson was part of an international team of anthropologists who discovered and analysed the marine mammal bones.
"Neanderthals could not have been that stupid and dumb," he says. "These people probably had a pretty good knowledge of the seasons and when to go hunting."
Finlayson and his colleague Yolanda Fernández-Jalvo, of Madrid's National Museum of Natural Sciences, discovered the bones in two cliff-base caves overlooking the Atlantic Ocean: Gorham's cave and Vanguard cave.
The sites, dating to around 40,000 years ago, also contain signs of hearths, tool-making and the remains of molluscs, boars and bears.
© Clive Finlayson, Gibraltar Museum
Thoracic vertebra of juvenile common dolphin from Vanguard cave
Thoracic vertebra of juvenile common dolphin from Vanguard cave
The discovery bolsters the image of Neanderthals as intelligent and adaptable hunters, rather than knuckle-dragging brutes, says Clive Finlayson of the Gibraltar Museum.
Finlayson was part of an international team of anthropologists who discovered and analysed the marine mammal bones.
"Neanderthals could not have been that stupid and dumb," he says. "These people probably had a pretty good knowledge of the seasons and when to go hunting."
Finlayson and his colleague Yolanda Fernández-Jalvo, of Madrid's National Museum of Natural Sciences, discovered the bones in two cliff-base caves overlooking the Atlantic Ocean: Gorham's cave and Vanguard cave.
The sites, dating to around 40,000 years ago, also contain signs of hearths, tool-making and the remains of molluscs, boars and bears.
© NASA/JPL-Caltech/STScI/CXC/SAO
Cassiopeia A is among the best-studied supernova remnants. This image blends data from NASA's Spitzer (red), Hubble (yellow), and Chandra (green and blue) observatories.
Cassiopeia A is among the best-studied supernova remnants. This image blends data from NASA's Spitzer (red), Hubble (yellow), and Chandra (green and blue) observatories.
Hot spots near the shattered remains of an exploded star are echoing the blast's first moments, say scientists using data from NASA's Spitzer Space Telescope.
Eli Dwek of NASA's Goddard Space Flight Center in Greenbelt, Md., and Richard Arendt of the University of Maryland, Baltimore County, say these echoes are powered by radiation from the supernova shock wave that blew the star apart some 11,000 years ago. "We're seeing the supernova's first flash," Dwek says.
Other Spitzer researchers discovered hot spots near the Cassiopeia A supernova remnant and recognized their importance as light echoes of the original blast. Dwek and Arendt used Spitzer data to probe this hot dust and pin down the cause of the echoes more precisely.
The "birth rate" for stars is certainly not easy to determine. Distances in the universe are far too great for astronomers to be able to count all the newly formed celestial bodies with the aid of a telescope. So it is fortunate that the emerging stars give themselves away by a characteristic signal known as "H-alpha" emissions. The larger the number of stars being formed in a particular region of the firmament, the more H-alpha rays are emitted from that region.
"H-alpha emissions only occur in the vicinity of very heavy stars," explains Jan Pflamm-Altenburg of the Argelander Institute of Astronomy at Bonn University. It has long been accepted that heavy and light stars are always born in a certain ratio to each other. One "H-alpha baby" is thought to be accompanied by 230 lighter stars with a mass too low for them to emit H-alpha rays.
"H-alpha emissions only occur in the vicinity of very heavy stars," explains Jan Pflamm-Altenburg of the Argelander Institute of Astronomy at Bonn University. It has long been accepted that heavy and light stars are always born in a certain ratio to each other. One "H-alpha baby" is thought to be accompanied by 230 lighter stars with a mass too low for them to emit H-alpha rays.
A new algorithm developed by a computer scientist at the University of Southampton can be used to predict political power balances.
In a paper entitled "Manipulating the Quota in Weighted Voting Games" published in the proceedings of the Association for the Advancement of Artificial Intelligence , Dr Edith Elkind at the University's School of Electronics and Computer Science (ECS) describes how a mathematical model developed to describe voting in a parliament, can facilitate decision making among groups of computerised agents.
'Agents tend to form coalitions in much the same way as political parties,' she said. 'So I thought it would be interesting to look at what would happen to the balance of power if you change the number of votes needed to make a decision.'
In her paper, Dr Elkind, who is part of ECS' Intelligence, Agents, Multimedia Group, illustrates that the power of a political party is very much dependent on whether bills are passed by a simple majority (50% of all votes) or a qualified majority (two thirds of all votes).
In a paper entitled "Manipulating the Quota in Weighted Voting Games" published in the proceedings of the Association for the Advancement of Artificial Intelligence , Dr Edith Elkind at the University's School of Electronics and Computer Science (ECS) describes how a mathematical model developed to describe voting in a parliament, can facilitate decision making among groups of computerised agents.
'Agents tend to form coalitions in much the same way as political parties,' she said. 'So I thought it would be interesting to look at what would happen to the balance of power if you change the number of votes needed to make a decision.'
In her paper, Dr Elkind, who is part of ECS' Intelligence, Agents, Multimedia Group, illustrates that the power of a political party is very much dependent on whether bills are passed by a simple majority (50% of all votes) or a qualified majority (two thirds of all votes).
Using a powerful radio telescope to peer into the early universe, a team of California astronomers has obtained the first direct measurement of a nascent galaxy's magnetic field as it appeared 6.5 billion years ago.
Astronomers believe the magnetic fields within our own Milky Way and other nearby galaxies - which control the rate of star formation and the dynamics of interstellar gas--arose from a slow "dynamo effect." In this process, slowly rotating galaxies are thought to have generated magnetic fields that grew very gradually as they evolved over 5 billion to 10 billion years to their current levels.
But in the October 2 issue of Nature, the astronomers report that the magnetic field they measured in this distant "protogalaxy" is at least 10 times greater than the average value in the Milky Way.
© NRAO/AUI
The astronomers used the world's largest fully steerable radio telescope, which stands 485 feet tall -- taller than the Statue of Liberty.
The astronomers used the world's largest fully steerable radio telescope, which stands 485 feet tall -- taller than the Statue of Liberty.
Astronomers believe the magnetic fields within our own Milky Way and other nearby galaxies - which control the rate of star formation and the dynamics of interstellar gas--arose from a slow "dynamo effect." In this process, slowly rotating galaxies are thought to have generated magnetic fields that grew very gradually as they evolved over 5 billion to 10 billion years to their current levels.
But in the October 2 issue of Nature, the astronomers report that the magnetic field they measured in this distant "protogalaxy" is at least 10 times greater than the average value in the Milky Way.
Comment: For those of you who would like to learn the secrets of Stonehenge, read Laura Knight-Jadczyk's The Secret History of the World.
This would probably be good advice for the above researchers, too.