An elliptical pen made of cobalt atoms set on a substrate of copper atoms. The electrons in this pen behave like standing waves in a pond. (Max Planck Institute for Microstructure Physics)

The conduction electrons can be imagined like a gas or a liquid; they form standing waves in circular atomic "pens" similar to waves in a small pond.

The arrangement of cobalt atoms on a substrate of copper atoms (left) and cerium atoms on a substrate of silver (right), each in a pen of cobalt or cerium. (Max Planck Institute for Microstructure Physics)

The physicists then simulated the effects of vapour-depositing cobalt adatoms. The new atoms interact with the cobalt atoms in the pen and with the enclosed electrons. There are tiny fluctuations in the energy levels which only have an effect at low temperatures of around 10 to 20 kelvins.

These fluctuations cause the adatoms to prefer to move to positions with higher densities of electrons, provided the number of vapour-deposited adatoms is correct, the temperature is low enough and the pen sufficiently secure.

The cobalt atoms arrange themselves, so to speak, like the waves in a pond of electrons in ellipses.

With adatoms, which can move more easily at lower temperatures, for example atoms of the element cerium and a circular enclosure, the researchers created regular structures on the circles themselves; this was similar to allowing sheep to run randomly into a pen where they obediently line up, spaced at regular intervals and in concentric circles.

The next step will be to offer experimental proof of the simulations, which should be possible with current atomic scanning force microscopy, and to find new ways to create thin films.

Max-Planck-Institute of Microstructure Physics - http://www.mpg.de/english

When the boys reached age 22, they were categorized into three groups: those who used only alcohol or tobacco, those who started with alcohol and tobacco and then used marijuana (gateway sequence) and those who used marijuana prior to alcohol or tobacco (reverse sequence).

Nearly a quarter of the study population who used both legal and illegal drugs at some point – 28 boys – exhibited the reverse pattern of using marijuana prior to alcohol or tobacco, and those individuals were no more likely to develop a substance use disorder than those who followed the traditional succession of alcohol and tobacco before illegal drugs, according to the study, which appears in this month’s issue of the American Journal of Psychiatry.

“The gateway progression may be the most common pattern, but it’s certainly not the only order of drug use,” said Ralph E. Tarter, Ph.D., professor of pharmaceutical sciences at the University of Pittsburgh School of Pharmacy and lead author of the study. “In fact, the reverse pattern is just as accurate for predicting who might be at risk for developing a drug dependence disorder.”

In addition to determining whether the gateway hypothesis was a better predictor of substance abuse than competing theories, the investigators sought to identify characteristics that distinguished users in the gateway sequence from those who took the reverse path.

Out of the 35 variables they examined, only three emerged to be differentiating factors: Reverse pattern users were more likely to have lived in poor physical neighborhood environments, had more exposure to drugs in their neighborhoods and had less parental involvement as young children.

Most importantly, a general inclination for deviance from sanctioned behaviors, which can become evident early in childhood, was strongly associated with all illicit drug use, whether it came in the gateway sequence, or the reverse.

While the gateway theory posits that each type of drug is associated with certain specific risk factors that cause the use of subsequent drugs, such as cigarettes or alcohol leading to marijuana, this study’s findings indicate that environmental aspects have stronger influence on which type of substance is used. That is, if it’s easier for a teen to get his hands on marijuana than beer, then he’ll be more likely to smoke pot.

Stash

This evidence supports what’s known as the common liability model, an emerging theory that states the likelihood that someone will transition to the use of illegal drugs is determined not by the preceding use of a particular drug but instead by the user’s individual tendencies and environmental circumstances.

“The emphasis on the drugs themselves, rather than other, more important factors that shape a person’s behavior, has been detrimental to drug policy and prevention programs,” Dr. Tarter said.

“To become more effective in our efforts to fight drug abuse, we should devote more attention to interventions that address these issues, particularly to parenting skills that shape the child’s behavior as well as peer and neighborhood environments.”

Indeed, according to the study, interventions focusing on behavior modification may be more effective prevention tactics than current anti-drug initiatives.

For example, providing guidance to parents – particularly those in high-risk neighborhoods – on how to boost their caregiving skills and foster bonding with their children, could have a measurable effect on a child’s likelihood to smoke marijuana.

Also, early identification of children who exhibit antisocial tendencies could allow for interventions before drug use even begins.

Although this research has significant implications for drug abuse prevention approaches, Dr. Tarter notes that the study has some limitations.

First, as only male behaviors were studied, further investigation should explore if the results apply to women as well. Also, the examination of behaviors in phases beyond alcohol and marijuana consumption in the gateway series will be necessary.

University of Pittsburgh Medical Center - http://www.upmc.edu

Yoshi Kohno, Carl Hartung and Scott Saponas (l-r) with devices they built to pick up on the Nike+iPod signal. (Mary Levin, UW News and Information)

Since its August release, retailers have sold more than 450,000 Nike+iPod Sport Kits, according to industry publication AppleInsider. The $29 item consists of two parts. One piece is a chip the size of a dinner mint that acts as a pedometer, which runners slip into their shoe.

The other piece is a receiver that fits into an iPod Nano and stores information beamed from the person's foot. After their workouts, high-tech runners can upload the data and use a Nike software program to track their distance, speed and calories burned.

But it turns out that the sensor in the shoe emits a signal detectable by any compatible receiver within a range of up to 60 feet, long after the workout has ended. The researchers concocted a variety of homemade devices able to pick up the sensor's unique signature.

The simplest connects a receiver from the Nike+iPod kit to a laptop's serial port, and the screen displays each device in range. A more sophisticated system uses a matchbox-sized computer with wireless Internet access to record multiple users' whereabouts, send the information to a central server, plot people's locations using GoogleMaps and alert the person doing the tracking with an e-mail or text message. All use the receiver sold with the kit, and each was built for less than $300.

The technical report describes possible scenarios. A thief could track when people enter or leave their homes. A jealous boyfriend could track a woman's movements, or compare them with the movements of a suspected rival. And although a receiver only picks up the signal when a person is within range, a stalker could hide receivers near a home, a gym and a restaurant, for example, to closely monitor his or her target's movements.

"Wanna buy an Apple?"

Researchers report that it took them about 10 minutes to figure out how to decode a receiver's unique tag and a few hours to write the code that interprets the sensor data. They estimate that an electronics hobbyist could build a system in a few hours, or at most a weekend. And if somebody posted sensor-scanning code on the Internet, it would be easy for others to build copycat devices.

The team tested the technology to track each other's movements and those of colleagues in the UW computer-science building. Ethical concerns prevented them from trying the device on unsuspecting targets. But because the signal can be picked up silently by any number of receivers, they say there's no way to know whether this spying technique has already been put into practice.

Though it has an off switch, the sensor is sold with the power on. Most users likely wouldn't bother to remove the gadget and turn the power off after each workout. Nike's online documentation reads: "Most Nike+iPod runners and walkers can just drop the sensor in their Nike+ shoes and forget about it."

The report suggests a number of ways the company could have made the device more secure using standard techniques from modern cryptography.

"There's a bigger issue here," says Kohno, the senior author on the paper. "When people buy a toaster, they know it's probably not going to blow up when they plug it in. But when they buy a consumer device like the Nike+iPod kit, they have no idea whether the device might enable someone to violate their privacy. We need to change that."

Click here for a video explanation of the research.

University of Washington - http://www.uwnews.org

A Burmese python

The python is one of the San’s most important animals. According to their creation myth, mankind descended from the python and the ancient, arid streambeds around the hills are said to have been created by the python as it circled the hills in its ceaseless search for water.

Sheila Coulson’s find shows that people from the area had a specific ritual location associated with the python. The ritual was held in a little cave on the northern side of the Tsodilo Hills. The cave itself is so secluded and access to it is so difficult that it was not even discovered by archaeologists until the 1990s.

When Coulson entered the cave this summer with her three master’s students, it struck them that the mysterious rock resembled the head of a huge python. On the six meter long by two meter tall rock, they found three-to-four hundred indentations that could only have been man-made.

Python Stone. (Sheila Coulson)

"You could see the mouth and eyes of the snake. It looked like a real python. The play of sunlight over the indentations gave them the appearance of snake skin. At night, the firelight gave one the feeling that the snake was actually moving".

They found no evidence that work had recently been done on the rock. In fact, much of the rock’s surface was extensively eroded.

When they saw the many indentations in the rock, the archaeologists wondered about more than when the work had been done. They also began thinking about what the cave had been used for and how long people had been going there. With these questions in mind, they decided to dig a test pit directly in front of the python stone.

At the bottom of the pit, they found many stones that had been used to make the indentations. Together with these tools, some of which were more than 70,000 years old, they found a piece of the wall that had fallen off during the work.

In the course of their excavation, they found more than 13,000 artifacts. All of the objects were spearheads and articles that could be connected with ritual use, as well as tools used in carving the stone.

They found nothing else.

As if that were not enough, the stones that the spearheads were made from are not from the Tsodilo region but must have been brought from hundreds of kilometers away.

The spearheads are better crafted and more colourful than other spearheads from the same time and area. Surprisingly enough, it was only the red spearheads that had been burned.

"Stone age people took these colourful spearheads, brought them to the cave, and finished carving them there. Only the red spearheads were burned. It was a ritual destruction of artifacts. There was no sign of normal habitation. No ordinary tools were found at the site. Our find means that humans were more organised and had the capacity for abstract thinking at a much earlier point in history than we have previously assumed. All of the indications suggest that Tsodilo has been known to mankind for almost 100,000 years as a very special place in the pre-historic landscape.” says Sheila Coulson.

Sheila Coulson also noticed a secret chamber behind the python stone. Some areas of the entrance to this small chamber were worn smooth, indicating that many people had passed through it over the years.

"The shaman, who is still a very important person in San culture, could have kept himself hidden in that secret chamber. He would have had a good view of the inside of the cave while remaining hidden himself. When he spoke from his hiding place, it could have seemed as if the voice came from the snake itself. The shaman would have been able to control everything. It was perfect.” The shaman could also have “disappeared” from the chamber by crawling out onto the hillside through a small shaft.

The spearheads were particularly beautiful and were brought from hundreds of kilometers away. (Sheila Coulson)

While large cave and wall paintings are numerous throughout the Tsodilo Hills, there are only two small paintings in this cave: an elephant and a giraffe. These images were rendered, surprisingly, exactly where water runs down the wall.

Sheila Coulson thinks that an explanation for this might come from San mythology.

In one San story, the python falls into a body of water and cannot get out by itself. The python is pulled from the water by a giraffe. The elephant, with its long trunk, is often used as a metaphor for the python.

"In the cave, we find only the San people’s three most important animals: the python, the elephant, and the giraffe. That is unusual. This would appear to be a very special place. They did not burn the spearheads by chance. They brought them from hundreds of kilometers away and intentionally burned them. So many pieces of the puzzle fit together here. It has to represent a ritual." concludes Sheila Coulson.

It was a major archaeological find five years ago that made it possible for Sheila Coulson to date the finds in this little cave in Botswana. Up until the turn of the century, archaeologists believed that human civilisation developed in Europe after our ancestors migrated from Africa. This theory was crushed by Archaeologist Christopher Henshilwood when he published his find of traces from a Middle Stone Age dwelling in the Blombos Cave in Southern Cape, South Africa.

Research Council of Norway - http://www.rcn.no/english

He says this indicates that recent efforts globally to reduce emissions have had little impact on emissions growth. “Recent emissions seem to be near the high end of the fossil fuel use scenarios used by the Intergovernmental Panel on Climate Change (IPCC). On our current path, it will be difficult to rein-in carbon emissions enough to stabilise the atmospheric carbon dioxide concentration at 450 ppm.”

Dr Raupach’s figures show that while China demonstrates the highest current growth rate in emissions, its emissions per person are still below the global average and its accumulated contribution since the start of the industrial revolution around 1800 is only five per cent of the global total. This compares to the US and Europe which have each contributed more than 25 per cent of accumulated global emissions.

Dr Raupach says that the amount of emitted carbon dioxide remaining in the atmosphere fluctuates from year to year due to natural factors such as El Niño.

However, he says that on average, nearly half of all emissions from fossil fuel use and land-use changes remain in the atmosphere, with the rest being absorbed by the land and oceans.

“When natural variability is smoothed out, 45 per cent of emissions have remained in the atmosphere each year over the past 50 years,” he says.

“A danger is that the land and oceans might take up less carbon dioxide in the future than they have in the past, which would increase the rate of climate change caused by emissions.”

The latest findings on greenhouse gas emissions are supported by measurements of the subsequent concentrations of carbon dioxide in the atmosphere.

Dr Paul Fraser, also from CSIRO Marine and Atmospheric Research, says that atmospheric concentrations of carbon dioxide grew by two parts per million in 2005, the fourth year in a row of above-average growth. “To have four years in a row of above-average carbon dioxide growth is unprecedented,” Dr Fraser says.

Dr Fraser says the 30-year record of air collected at the Australian Bureau of Meteorology’s observation station in Cape Grim, showed growth rates of just over one part per million in the early 1980s, but in recent years carbon dioxide has increased at almost twice this rate. “The trend over recent years suggests the growth rate is accelerating, signifying that fossil fuels are having an impact on greenhouse gas concentrations in a way we haven’t seen in the past.”

Drs Raupach and Fraser presented their latest findings last week during the Annual Science Meeting at Tasmania’s Cape Grim Baseline Air Pollution Station, which is managed by the Australian Bureau of Meteorology to monitor and study global atmospheric composition in a program led by CSIRO and the Bureau.

Commonwealth Scientific and Industrial Research Organisation - http://www.csiro.au

Ray Charles

December 4, 2006 - Ray Charles was really good at snapping, said musical acoustician Kenneth Lindsay of Southern Oregon University in Ashland. Charles's snaps that open "It Don't Mean a Thing (If It Ain't Got That Swing)" are timed so well that he is never more than 5 milliseconds off the tight beat.

Lindsay studies the physics of the sound of swing music such as Ray Charles' hits, and in a talk last week at the Acoustical Society of America's joint meeting in Honolulu with the Acoustical Society of Japan, he explained how he created a visual analysis of the bouncy, energetic, even lopsided musical style of swing.

"If you're tapping your feet, that's swing," he said. To study swing, he looked at the popular dance music in all cultures -- a loose rhythmic style that's different from syncopation, in which a note is played when a pause is expected or an expected note isn't played. Swing, he said, relies on drama and emotion, and a micro-timing of pulses and meter that aren't found in other styles. Swing uses a lot of triplets, irregular notes that are 2/3 the length of a regular note.

Swing is found in American jazz, Caribbean beats, Brazilian swingee, reggae, samba and many other musical styles around the world.

To really see what this universal but mysterious music looked like, Lindsay broke down famous swing songs like "Fever" and "Graceland" in various ways. He measured the song's notes and pulses very finely, to within 3-10 milliseconds per musical event, sometimes even fine-tuning the differences between the sounds to a half a millisecond. This way he could separate out instruments, voices and drums by their pitch and note. He created graphs that separated out the instruments. That's how he noticed Ray Charles' incredibly tight snapping.

American Institute of Physics - http://www.aip.org

Seagrass (NOAA)

"The fate of seagrasses can provide resource managers advance signs of deteriorating ecological conditions caused by poor water quality and pollution."

Among its findings, the study analyzed an apparent disconnect between the scientific community’s concerns over seagrass habitat and its coverage in the popular media.

While recent studies rank seagrass as one of the most valuable habitat in coastal systems, media coverage of other habitats – including salt marshes, mangroves and coral reefs – receive 3 to 100-fold more media attention than seagrass systems.

"Translating scientific understanding of the value of seagrass ecosystems into public awareness, and thus effective seagrass management and restoration, has not been as effective as for other coastal ecosystems, such as salt marshes, mangroves, or coral reefs," said co-author Dr. Robert Orth of the Virginia Institute of Marine Science. "Elevating public awareness about this impending crisis is critical to averting it."

"This report is a call to the world’s coastal managers that we need to do more to protect seagrass habitat," said co-author Dr. Tim Carruthers of the University of Maryland Center for Environmental Science.

"Seagrasses are just one of the many keys to maintaining healthy coastal ecosystems and their biodiversity."

Seagrasses – a unique group of flowering plants that have adapted to exist fully submersed in the sea – profoundly influence the physical, chemical and biological environments of coastal waters. They provide critical habitat for aquatic life, alter water flow and can help mitigate the impact of nutrient and sediment pollution.

University of Maryland Center for Environmental Science - http://www.umces.edu

The Antikythera Mechanism, a clock-like astronomical calculator dating from the second century BC

Reconstruction of the Antikythera Mechanism from a few years ago by John Gleave, an orrery maker based in the United Kingdom.

Professor Edmunds said: "This device is just extraordinary, the only thing of its kind. The design is beautiful, the astronomy is exactly right. The way the mechanics are designed just makes your jaw drop. Whoever has done this has done it extremely well."

The team was made up of researchers from Cardiff, the National Archaeological Museum of Athens and the Universities of Athens and Thessaloniki, supported by a substantial grant from the Leverhulme Trust. They were greatly aided by Hertfordshire X-Tek, who developed powerful X-Ray computer technology to help them study the corroded fragments of the machine.

Computer giant Hewlett-Packard provided imaging technology to enhance the surface details of the machine.

The mechanism is in over 80 pieces and stored in precisely controlled conditions in Athens where it cannot be touched. Recreating its workings was a difficult, painstaking process, involving astronomers, mathematicians, computer experts, script analysts and conservation experts.

The team is unveiling its full findings at a two-day international conference in Athens from November 30 to December 1 and publishing the research in the journal Nature .

The researchers are now hoping to create a computer model of how the machine worked, and, in time, a full working replica.

It is still uncertain what the ancient Greeks used the mechanism for, or how widespread this technology was.

Professor Edmunds said: "It does raise the question what else were they making at the time. In terms of historic and scarcity value, I have to regard this mechanism as being more valuable than the Mona Lisa."

Cardiff University - http://www.cardiff.ac.uk