Honeybee hordes use two weapons - heat and carbon dioxide - to kill their natural enemies, giant hornets.
Japanese honeybees form "bee balls" - mobbing and smothering the predators.
This has previously been referred to as "heat-balling", but a study has now shown that carbon dioxide also plays a role in its lethal effectiveness.
In the journal Naturwissenschaften, the scientists describe how hornets are killed within 10 minutes when they are trapped inside a ball of bees.
Japanese giant hornets, which can be up to 5cm long, are voracious predators that can devastate bees' nests and consume their larvae.
But, if the bees spot their attacker in time, they mount a powerful defence in the form of a bee ball. This study found that the heat inside the bee ball alone was not enough to reliably kill the hornets
"They can survive for 10 minutes at a temperature up to 47C, and the temperature inside the bee balls does not rise higher than 46C," said Fumio Sakamoto, a researcher from Kyoto Gakuen University in Japan, and one of the authors of the study.
His team recreated experimental bee balls and took direct measurements from inside them.
They anaesthetised giant hornets and fixed them to the tip either of a thermometer probe, or the inlet of a gas detector.
Once the hornets recovered from their anaesthesia, the probes were touched to the bees' nest.
"The bee ball formed (around the hornet) immediately," said Dr Sakamoto.
After 10 minutes the bees were packed solidly enough around the probe to be removed from the nest in a distinct ball.
As the temperature inside the ball increased to more than 45C, the carbon dioxide level also rose sharply.
In a parallel experiment, the scientists found that in an atmosphere relatively high in carbon dioxide, the temperature at which hornets could survive for 10 minutes was lowered.
"So we concluded that carbon dioxide produced inside the bee ball by the honeybees is a major factor, together with temperature, involved in the bees' defence."
Dr Sakamoto is not sure, at this point, whether the bees were effectively "gassing" the hornets, or simply depriving them of oxygen.
"Either way, the carbon dioxide increase and/or the oxygen decrease lowered the temperature that was lethal to the hornets, " he told BBC News.
"We are going to do the additional experiments about this point using mixed air of various oxygen and carbon dioxide (concentrations)."
The mob of bees also appeared to operate in "two phases".
"The hornet may be killed during the first 0-5 minute period, in which the highest level of heat production and carbon dioxide emissions take place," said Dr Sakamoto.
This might suggest that the bees are aware of what physiological state the hornet is in.
Dr Sakamoto said: "The latter 5-10 min period may be free running to ensure their victim's death."
Tuesday, July 7, 2009
Aquatic deer and ancient whales
If you startled a deer, you might not expect it to jump into the nearest pond and submerge itself for minutes.
But that is exactly what two species of mouse-deer in Asia do when confronted by predators, scientists have found.
One other African mouse-deer species is known to do the same thing, but the new discovery suggests all ruminants may once have had an affinity with water.
It also lends support to the idea that whales evolved from water-loving creatures that looked like small deer.
There are around 10 species of mouse-deer, which are also called 'chevrotains'.
All belong to the ancient ruminant family Tragulidae, which split some 50 million years ago from other ruminants, the group that went on to evolve into cattle, goats, sheep, deer and antelope.
Deer are supposed to walk on land and graze not swim underwater
Zoologist Erik Meijaard
Each are small, deer-like creatures that unusually don't have antlers or horns. Instead they have large upper canine teeth, which in the males project down either side of the lower jaw.
The largest species, which stands no more than 80cm tall, lives in Africa and is thought to be the most primitive of all mouse-deer. Known as the water-chevrotain, this animal likes to live in swampy habitats. When alarmed, it dashes for the nearest river where it submerges and swims underwater to safety.
All of the other species of mouse-deer, which live in southeast Asia and India and Sri Lanka were thought to be dry-land animals.
Diving deer
That was until researchers witnessed some remarkable behaviour during two separate incidents.
The first occurred in June 2008 during a biodiversity survey in northern Central Kalimantan Province in Borneo, Indonesia.
During the survey, observers saw a mouse-deer swimming in a forest stream. When the animal noticed the observers it submerged. Over the next hour, they saw it come to the surface four or five times, and maybe more unseen. But it often remained submerged for more than five minutes at a time.
Eventually the observers caught the animal, which they identified as a pregnant female, then released it unharmed.
Among the survey team was the wife of Erik Meijaard, a senior ecologist working with the Nature Conservancy in Balikpapan, Indonesia.
Meijaard knew of anecdotal reports by local people who described deer hiding in creeks and rivers when chased by their dogs. When he saw photos of the deer he identified it as a greater mouse-deer
The same year, Meijaard also heard reports of a mouse-deer in Sri Lanka that had also been seen swimming underwater.
Three observers saw a mountain mouse-deer (Moschiola spp) run into a pond and start to swim, hotly pursued by a brown mongoose. The mouse-deer submerged itself, and eventually the mongoose retreated. The deer left the water only to be chased straight back into it by the mongoose.
"It came running again and dived into the water and swam underwater. I photographed this clearly and it became clear to me at this stage that swimming was an established part of its escape repertoire," says Gehan de Silva Wijeyeratne, who saw the incident.
"Seeing it swim underwater was a shock. Many mammals can swim in water. But other than those which are adapted for an aquatic existence, swimming is clumsy. The mouse-deer seemed comfortable, it seemed adapted," he says.
Origins of whales
Meijaard, Wijeyeratne and Umilaela, who saw the submerged Bornean mouse-deer, describe both incidents in the journal Mammalian Biology.
"This is the first time that this behaviour has been described for Asian mouse-deer species," says Meijaard. "I was very excited when I heard the mouse-deer stories because it resolved one of those mysteries that local people had told me about but that had remained hidden to science."
"The behaviour is interesting because it is unexpected. Deer are supposed to walk on land and graze not swim underwater. But more interestingly for the zoologist are the evolutionary implications," he says.
The behaviour bolsters one leading theory regarding the origin of whales.
In 2007, scientists led by Hans Thewissen of the Northeastern Ohio Universities College of Medicine in Ohio published details of a remarkable fossil called Indohyus.
This fossil was of a ruminant animal that looked like a small deer, but also had morphological features that showed it could be an ancestor of early whales.
Although speculative, that suggests that all early ruminants may also have led a partially aquatic lifestyle.
The discovery that two Asian species of mouse-deer are comfortable underwater shows that at least three species of modern tragulid share an aquatic escape behaviour.
Because these species diverged at least 35 million years ago, their ancestor also likely behaved in the same way, again bolstering the the idea that a deer-like ruminant may have evolved to produce the modern cetacean group of whales and dolphins.
Hippos, the closest modern relative of whales, also dive for water when threatened, a behaviour that may have been lost over time by other modern species such as sheep and antelope.
But that is exactly what two species of mouse-deer in Asia do when confronted by predators, scientists have found.
One other African mouse-deer species is known to do the same thing, but the new discovery suggests all ruminants may once have had an affinity with water.
It also lends support to the idea that whales evolved from water-loving creatures that looked like small deer.
There are around 10 species of mouse-deer, which are also called 'chevrotains'.
All belong to the ancient ruminant family Tragulidae, which split some 50 million years ago from other ruminants, the group that went on to evolve into cattle, goats, sheep, deer and antelope.
Deer are supposed to walk on land and graze not swim underwater
Zoologist Erik Meijaard
Each are small, deer-like creatures that unusually don't have antlers or horns. Instead they have large upper canine teeth, which in the males project down either side of the lower jaw.
The largest species, which stands no more than 80cm tall, lives in Africa and is thought to be the most primitive of all mouse-deer. Known as the water-chevrotain, this animal likes to live in swampy habitats. When alarmed, it dashes for the nearest river where it submerges and swims underwater to safety.
All of the other species of mouse-deer, which live in southeast Asia and India and Sri Lanka were thought to be dry-land animals.
Diving deer
That was until researchers witnessed some remarkable behaviour during two separate incidents.
The first occurred in June 2008 during a biodiversity survey in northern Central Kalimantan Province in Borneo, Indonesia.
During the survey, observers saw a mouse-deer swimming in a forest stream. When the animal noticed the observers it submerged. Over the next hour, they saw it come to the surface four or five times, and maybe more unseen. But it often remained submerged for more than five minutes at a time.
Eventually the observers caught the animal, which they identified as a pregnant female, then released it unharmed.
Among the survey team was the wife of Erik Meijaard, a senior ecologist working with the Nature Conservancy in Balikpapan, Indonesia.
Meijaard knew of anecdotal reports by local people who described deer hiding in creeks and rivers when chased by their dogs. When he saw photos of the deer he identified it as a greater mouse-deer
The same year, Meijaard also heard reports of a mouse-deer in Sri Lanka that had also been seen swimming underwater.
Three observers saw a mountain mouse-deer (Moschiola spp) run into a pond and start to swim, hotly pursued by a brown mongoose. The mouse-deer submerged itself, and eventually the mongoose retreated. The deer left the water only to be chased straight back into it by the mongoose.
"It came running again and dived into the water and swam underwater. I photographed this clearly and it became clear to me at this stage that swimming was an established part of its escape repertoire," says Gehan de Silva Wijeyeratne, who saw the incident.
"Seeing it swim underwater was a shock. Many mammals can swim in water. But other than those which are adapted for an aquatic existence, swimming is clumsy. The mouse-deer seemed comfortable, it seemed adapted," he says.
Origins of whales
Meijaard, Wijeyeratne and Umilaela, who saw the submerged Bornean mouse-deer, describe both incidents in the journal Mammalian Biology.
"This is the first time that this behaviour has been described for Asian mouse-deer species," says Meijaard. "I was very excited when I heard the mouse-deer stories because it resolved one of those mysteries that local people had told me about but that had remained hidden to science."
"The behaviour is interesting because it is unexpected. Deer are supposed to walk on land and graze not swim underwater. But more interestingly for the zoologist are the evolutionary implications," he says.
The behaviour bolsters one leading theory regarding the origin of whales.
In 2007, scientists led by Hans Thewissen of the Northeastern Ohio Universities College of Medicine in Ohio published details of a remarkable fossil called Indohyus.
This fossil was of a ruminant animal that looked like a small deer, but also had morphological features that showed it could be an ancestor of early whales.
Although speculative, that suggests that all early ruminants may also have led a partially aquatic lifestyle.
The discovery that two Asian species of mouse-deer are comfortable underwater shows that at least three species of modern tragulid share an aquatic escape behaviour.
Because these species diverged at least 35 million years ago, their ancestor also likely behaved in the same way, again bolstering the the idea that a deer-like ruminant may have evolved to produce the modern cetacean group of whales and dolphins.
Hippos, the closest modern relative of whales, also dive for water when threatened, a behaviour that may have been lost over time by other modern species such as sheep and antelope.
Physical Reality Of String Theory Shown In Quantum-critical State Of Electrons
String theory has come under fire in recent years. Promises have been made that have not been lived up to. Leiden theoretical physicists have now for the first time used string theory to describe a physical phenomenon -- the quantum-critical state of electrons leading to high-temperature superconductivity. Their discovery has been reported recently in the journal Science
Electrons can form a special kind of state, a so-called quantum critical state, that plays a role in high-temperature superconductivity. Superconductivity at high temperatures has long been a 'hot issue' in physics. In superconductivity, discovered by Heike Kamerlingh Onnes in Leiden, electrons can zoom through a material without meeting any resistance. In the first instance, this only seemed possible at very low temperatures close to absolute zero, but more and more examples are coming up where it also occurs at higher temperatures. So far, nobody has managed to explain high temperature superconductivity.
Jan Zaanen makes no attempt to hide his enthusiasm. Together with Mihailo Cubrovic and Koenraad Schalm, he has successfully managed to shed light on a previously unexplained natural phenomenon using the mathematics of string theory.
Theory of everything
This is the first time that a calculation based on string theory has been published in Science, even though the theory is widely known. "There have always been a lot of expectations surrounding string theory," Zaanen explains, having himself studied the theory to satisfy his own curiosity. "String theory is often seen as a child of Einstein that aims to devise a revolutionary and comprehensive theory, a kind of 'theory of everything.' Ten years ago, researchers even said: 'Give us two weeks and we'll be able to tell you where the big bang came from.' The problem of string theory was that, in spite of its excellent maths, it was never able to make a concrete link with the physical reality -- the world around us."
Quantum soup
But now, Zaanen, together with his colleagues Cubrovic and Schalm, are trying to change this situation, by applying string theory to a phenomenon that physicists, including Zaanen, have for the past fifteen years been unable to explain: the quantum-critical state of electrons. This special state occurs in a material just before it becomes superconductive at high temperature. Zaanen describes the quantum-critical state as a 'quantum soup', whereby the electrons form a collective independent of distances, where the electrons exhibit the same behaviour at small quantum mechanical scale or at macroscopic human scale.
Bridge
Because of Zaanen's interest in string theory, he and string theorist Koenraad Schalm soon became acquainted after Schalm's arrival in Leiden. Zaanen had an unsolved problem and Schalm was an expert in the field of string theory. Their common interest brought them together, and they decided to work jointly on the research. They used the aspect of string theory known as AdS/CFT correspondence. This allows situations in a large relativistic world to be translated into a description at minuscule quantum physics level. This correspondence bridges the gap between these two different worlds. By applying the correspondence to the situation where a black hole vibrates when an electron falls into it, they arrived at the description of electrons that move in and out of a quantum-critical state.
Puzzle
After days and nights of hard grind, it was a puzzle that fitted. "We hadn't expected it to work so well," says a delighted Zaanen. "The maths was a perfect fit; it was superb. When we saw the calculations, at first we could hardly believe it, but it was right." Gateway to moreAlthough the mystery of high temperature superconductivity isn't fully resolved, the findings do show that major problems in physics can be addressed using string theory. And this is just the start, Zaanen believes. "AdS/CFT correspondence now explains things that colleagues who have been beavering away for ages were unable to resolve, in spite of their enormous efforts. There are a lot of things that can be done with it. We don't fully understand it yet, but I see it as a gateway to much more."
Electrons can form a special kind of state, a so-called quantum critical state, that plays a role in high-temperature superconductivity. Superconductivity at high temperatures has long been a 'hot issue' in physics. In superconductivity, discovered by Heike Kamerlingh Onnes in Leiden, electrons can zoom through a material without meeting any resistance. In the first instance, this only seemed possible at very low temperatures close to absolute zero, but more and more examples are coming up where it also occurs at higher temperatures. So far, nobody has managed to explain high temperature superconductivity.
Jan Zaanen makes no attempt to hide his enthusiasm. Together with Mihailo Cubrovic and Koenraad Schalm, he has successfully managed to shed light on a previously unexplained natural phenomenon using the mathematics of string theory.
Theory of everything
This is the first time that a calculation based on string theory has been published in Science, even though the theory is widely known. "There have always been a lot of expectations surrounding string theory," Zaanen explains, having himself studied the theory to satisfy his own curiosity. "String theory is often seen as a child of Einstein that aims to devise a revolutionary and comprehensive theory, a kind of 'theory of everything.' Ten years ago, researchers even said: 'Give us two weeks and we'll be able to tell you where the big bang came from.' The problem of string theory was that, in spite of its excellent maths, it was never able to make a concrete link with the physical reality -- the world around us."
Quantum soup
But now, Zaanen, together with his colleagues Cubrovic and Schalm, are trying to change this situation, by applying string theory to a phenomenon that physicists, including Zaanen, have for the past fifteen years been unable to explain: the quantum-critical state of electrons. This special state occurs in a material just before it becomes superconductive at high temperature. Zaanen describes the quantum-critical state as a 'quantum soup', whereby the electrons form a collective independent of distances, where the electrons exhibit the same behaviour at small quantum mechanical scale or at macroscopic human scale.
Bridge
Because of Zaanen's interest in string theory, he and string theorist Koenraad Schalm soon became acquainted after Schalm's arrival in Leiden. Zaanen had an unsolved problem and Schalm was an expert in the field of string theory. Their common interest brought them together, and they decided to work jointly on the research. They used the aspect of string theory known as AdS/CFT correspondence. This allows situations in a large relativistic world to be translated into a description at minuscule quantum physics level. This correspondence bridges the gap between these two different worlds. By applying the correspondence to the situation where a black hole vibrates when an electron falls into it, they arrived at the description of electrons that move in and out of a quantum-critical state.
Puzzle
After days and nights of hard grind, it was a puzzle that fitted. "We hadn't expected it to work so well," says a delighted Zaanen. "The maths was a perfect fit; it was superb. When we saw the calculations, at first we could hardly believe it, but it was right." Gateway to moreAlthough the mystery of high temperature superconductivity isn't fully resolved, the findings do show that major problems in physics can be addressed using string theory. And this is just the start, Zaanen believes. "AdS/CFT correspondence now explains things that colleagues who have been beavering away for ages were unable to resolve, in spite of their enormous efforts. There are a lot of things that can be done with it. We don't fully understand it yet, but I see it as a gateway to much more."
Engineer Designs More Efficient, Quieter Bus
An engineer has designed an electric bus that runs on battery power. Putting motors in each wheel makes a transmission and driveshaft unnecessary, and allows the bus to ride closer to the ground for ease of entry. Using stainless steel also reduces weight. The prototype increases fuel efficiency by four times over a more traditional city bus.
Most of us gladly ride in cars, airplanes, even trains -- but buses? There's a bit of a stigma attached to them. Now, one engineer has a built a new type of city bus he hopes will make people want to ride. Al Gore brought the issue of global warming to the big screen. One of the biggest offenders? Carbon dioxide. The latest international report says it's responsible for 60 percent of the greenhouse gases. So automotive engineer Bruce Emmons decided to do something about it. He created a 40 foot battery powered and electric city bus -- it's like a giant golf cart!
"Inside of the bus, we have what actually propels the bus," Emmons says. "This is what makes it go." Batteries and motor controllers drive electric motors in the wheels. And instead of the bus being made from regular steel, "Everything is built of this incredible high-strength stainless steel," Emmons explains.
The steel is as lightweight as aluminum, making the bus half the weight of a normal bus. Steel tubes also support the front bumper and are designed to turn inside out in a crash to absorb energy and soften the blow.
With no transmission, drive shafts or other bulky mechanics taking up space, the floor can be low, making it easier to get in and out of. And he promises a quieter, smoother ride.
"You can have a very efficient bus, but if nobody likes to ride on it, then it doesn't really help the fuel economy." Emmons' bus boasts four-times the fuel economy of a standard one. His next goal -- to get it from the lab to buses all over the city streets. Right now the bus is just a prototype. It has the potential to be different types of a hybrid -- such as a fuel cell or hydrogen bus.
show background -->
BACKGROUND: A hybrid electric bus that weighs half as much as conventional buses, boasts three times the fuel economy, and can carry 20% more passengers, could debut by the middle of 2008. The bus would also be quieter and would have less environmental impact than standard diesel-powered buses, resulting in significant cost savings. It is being developed by a collaboration between Autokinetics, Oak Ridge National Laboratory, and the Department of Energy's FreedomCAR and Vehicle Technologies Program.
LESS IS MORE: At the heart of the bus is an ultra-high-strength stainless steel body and chassis that would be up to 30% less expensive to build than the standard bus body. The lighter weight of the bus improves fuel efficiency by reducing drag. The weight (technically, the mass) of the vehicle determines how much energy is needed to get it moving, or to change direction. As the vehicle accelerates, it gains speed, but it also experiences an increase in drag, the friction from the air passing by. It takes extra energy to overcome that drag. A similar effect happens on a bicycle: it takes more exertion on the part of the rider while biking into a strong headwind, than when the wind is at the rider's back. So any decrease in drag that a vehicle experiences will result in better fuel economy.
WHAT ARE HYBRIDS: Gasoline-powered cars are the most common type, although there are some battery-powered electric cars available today. A hybrid vehicle is a combination of the two, attempting to reap the best of both approaches. Current hybrid engine systems have a single mode of operation, using a single gear set to split the engine's power into two systems -- routing it to drive the wheels or charge the battery -- for both city and highway driving. A hybrid engine also captures energy from braking that would otherwise be lost and shutting off the engine at a stop. The battery alone can power the vehicle at low speeds. The electric motor can double as a generator while braking and only has to run part of the time. One disadvantage is that the gasoline engine must therefore run at varying speeds, which reduces its energy efficiency.
CRASH TEST: Scientists at Oak Ridge National Laboratory have performed computer simulations of collision scenarios to ensure that the buses meet safety standards for reducing the impact of a collision. Every vehicle has what is known as a 'crumple zone,' that absorbs energy upon impact. It increases the amount of time it takes to come to a complete stop, spreading the force over a longer period of time. Because they yield during a collision, crumple zones change the energy of the impact into heat and sound, reducing the chance of injury to passengers
Most of us gladly ride in cars, airplanes, even trains -- but buses? There's a bit of a stigma attached to them. Now, one engineer has a built a new type of city bus he hopes will make people want to ride. Al Gore brought the issue of global warming to the big screen. One of the biggest offenders? Carbon dioxide. The latest international report says it's responsible for 60 percent of the greenhouse gases. So automotive engineer Bruce Emmons decided to do something about it. He created a 40 foot battery powered and electric city bus -- it's like a giant golf cart!
"Inside of the bus, we have what actually propels the bus," Emmons says. "This is what makes it go." Batteries and motor controllers drive electric motors in the wheels. And instead of the bus being made from regular steel, "Everything is built of this incredible high-strength stainless steel," Emmons explains.
The steel is as lightweight as aluminum, making the bus half the weight of a normal bus. Steel tubes also support the front bumper and are designed to turn inside out in a crash to absorb energy and soften the blow.
With no transmission, drive shafts or other bulky mechanics taking up space, the floor can be low, making it easier to get in and out of. And he promises a quieter, smoother ride.
"You can have a very efficient bus, but if nobody likes to ride on it, then it doesn't really help the fuel economy." Emmons' bus boasts four-times the fuel economy of a standard one. His next goal -- to get it from the lab to buses all over the city streets. Right now the bus is just a prototype. It has the potential to be different types of a hybrid -- such as a fuel cell or hydrogen bus.
show background -->
BACKGROUND: A hybrid electric bus that weighs half as much as conventional buses, boasts three times the fuel economy, and can carry 20% more passengers, could debut by the middle of 2008. The bus would also be quieter and would have less environmental impact than standard diesel-powered buses, resulting in significant cost savings. It is being developed by a collaboration between Autokinetics, Oak Ridge National Laboratory, and the Department of Energy's FreedomCAR and Vehicle Technologies Program.
LESS IS MORE: At the heart of the bus is an ultra-high-strength stainless steel body and chassis that would be up to 30% less expensive to build than the standard bus body. The lighter weight of the bus improves fuel efficiency by reducing drag. The weight (technically, the mass) of the vehicle determines how much energy is needed to get it moving, or to change direction. As the vehicle accelerates, it gains speed, but it also experiences an increase in drag, the friction from the air passing by. It takes extra energy to overcome that drag. A similar effect happens on a bicycle: it takes more exertion on the part of the rider while biking into a strong headwind, than when the wind is at the rider's back. So any decrease in drag that a vehicle experiences will result in better fuel economy.
WHAT ARE HYBRIDS: Gasoline-powered cars are the most common type, although there are some battery-powered electric cars available today. A hybrid vehicle is a combination of the two, attempting to reap the best of both approaches. Current hybrid engine systems have a single mode of operation, using a single gear set to split the engine's power into two systems -- routing it to drive the wheels or charge the battery -- for both city and highway driving. A hybrid engine also captures energy from braking that would otherwise be lost and shutting off the engine at a stop. The battery alone can power the vehicle at low speeds. The electric motor can double as a generator while braking and only has to run part of the time. One disadvantage is that the gasoline engine must therefore run at varying speeds, which reduces its energy efficiency.
CRASH TEST: Scientists at Oak Ridge National Laboratory have performed computer simulations of collision scenarios to ensure that the buses meet safety standards for reducing the impact of a collision. Every vehicle has what is known as a 'crumple zone,' that absorbs energy upon impact. It increases the amount of time it takes to come to a complete stop, spreading the force over a longer period of time. Because they yield during a collision, crumple zones change the energy of the impact into heat and sound, reducing the chance of injury to passengers
Orthodontists Diagnose Sleep Apnea More Easily with X-Rays
Diagnosing sleep apnea -- a chronic condition that causes teen-agers to stop breathing during sleep -- is difficult and often means staying at an overnight sleep lab. A new test can spot with problem with simple X-rays, by checking the position of the tongue and hyoid bone. If the bone sits lower, patients are more likely to have the condition. In a recent study, the X-rays correctly identified 70 percent of teens with sleep apnea.
Being a teenager is tough these days, but it's especially tough if you're always tired. Now a simple X-ray taken at your children's orthodontist could hold the key to helping them sleep better.
Sixteen-year-old Andrew Dudash would come home from school each day and go straight to bed. "I actually got a detention in school for sleeping during a class," he says.
Doctors diagnosed him with sleep apnea, a chronic condition that causes him to stop breathing during sleep. Diagnosing the condition is difficult and often means staying at an overnight sleep lab. But orthodontist Mark Hans wants to make that diagnosis easier. He's studying whether the same X-rays teens get before getting braces will help determine if they're at risk for sleep apnea.
"We're trying to give the sleep doctor a better chance of examining the right patients for this condition," says Dr. Hans, of Case Western Reserve University School of Dental Medicine in Cleveland.
Dr. Hans looks at the position of the tongue and hyoid bone. If the bone sits higher, patients are not at risk for sleep apnea. If it falls lower, they are more likely to have the condition.
In a recent study, the X-rays correctly identified 70 percent of teens with sleep apnea. Dr. Hans says, "When you identify chronic illness early and treat it early, you really prevent more long-term problems."
Case School of Medicine pediatric pulmonologist and sleep specialist Carol Rosen, says the X-rays would help. "This would add another feature that we would look for in our evaluation." So teens like Dudash can get the treatment they need.
"There's definitely a difference in my sleep because I'm not waking up much during the night," Dudash says. And his sleep is not something he's willing to gamble on.
Dr. Hans says there's no disadvantage to performing the X-ray other than a minimal dose of radiation, which is equivalent to a day in the sun. He says most insurance covers the X-rays, which cost about $100. A sleep lab evaluation could cost thousands.
show background -->
BACKGROUND: Researchers at Case Western Reserve University in Cleveland, Ohio, have identified two key factors in sleep apnea in teenagers. They used radiography (an imaging technique used by orthodontists) to study a group of teens to determine if they were likely to suffer from the condition. The technique will be used for earlier diagnosis for sleep apnea in teens before they become adults.
THE STUDY: The investigators studied the case histories of 590 patients between 7 and 8 years of age attending the orthodontic clinic at Case Dental School. Sixty of these patients -- a group least at risk and a group most at risk for sleep apnea -- underwent unattended in-home sleep monitoring.
WHAT IS SLEEP APNEA: Sleep apnea is a temporary suspension of breathing during sleep, which can have potentially serious consequences. People with sleep apnea can stop breathing for 10 to 30 seconds at a time, as many as 400 times a night. Most sleep apneas are the result of something blocking the passage of windpipe of the throat that brings air into the body. The tongue, tonsils, or uvula (the little piece of flesh that hangs down in the back of the throat) can all sometimes produce blockage, as can severe obesity: excess fat can block the airway. Some 12 million Americans suffer from sleep apnea, but men and those over 40 years of age are more likely to have the condition. Risk factors include heavy snoring, excess weight, high blood pressure, and any physical abnormality in the nose or throat.
WHAT ARE X-RAYS: X-rays are light waves.
The only difference between X-rays and the light that we see is that the X-rays have a higher energy level, and a shorter wavelength, making them undetectable to the human eye. Because they have so much energy, the particles that make up light, called photons, in X-rays can pass through most materials. It all depends on the size of the atoms that make up the material; larger atoms absorb X-ray photons. But smaller atoms do not, and the X-rays pass right through.
The soft tissue in the body is made of smaller atoms and doesn't absorb X-rays very well, but calcium atoms in the bones are much larger and do absorb X-rays. A camera on the other side of the patient records the patterns of X-ray light passing through the patient's body.
It's the same basic technology as that used in an ordinary camera, but X-ray light, instead of visible light, sets off the chemical reaction on the photographic plate.
Being a teenager is tough these days, but it's especially tough if you're always tired. Now a simple X-ray taken at your children's orthodontist could hold the key to helping them sleep better.
Sixteen-year-old Andrew Dudash would come home from school each day and go straight to bed. "I actually got a detention in school for sleeping during a class," he says.
Doctors diagnosed him with sleep apnea, a chronic condition that causes him to stop breathing during sleep. Diagnosing the condition is difficult and often means staying at an overnight sleep lab. But orthodontist Mark Hans wants to make that diagnosis easier. He's studying whether the same X-rays teens get before getting braces will help determine if they're at risk for sleep apnea.
"We're trying to give the sleep doctor a better chance of examining the right patients for this condition," says Dr. Hans, of Case Western Reserve University School of Dental Medicine in Cleveland.
Dr. Hans looks at the position of the tongue and hyoid bone. If the bone sits higher, patients are not at risk for sleep apnea. If it falls lower, they are more likely to have the condition.
In a recent study, the X-rays correctly identified 70 percent of teens with sleep apnea. Dr. Hans says, "When you identify chronic illness early and treat it early, you really prevent more long-term problems."
Case School of Medicine pediatric pulmonologist and sleep specialist Carol Rosen, says the X-rays would help. "This would add another feature that we would look for in our evaluation." So teens like Dudash can get the treatment they need.
"There's definitely a difference in my sleep because I'm not waking up much during the night," Dudash says. And his sleep is not something he's willing to gamble on.
Dr. Hans says there's no disadvantage to performing the X-ray other than a minimal dose of radiation, which is equivalent to a day in the sun. He says most insurance covers the X-rays, which cost about $100. A sleep lab evaluation could cost thousands.
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BACKGROUND: Researchers at Case Western Reserve University in Cleveland, Ohio, have identified two key factors in sleep apnea in teenagers. They used radiography (an imaging technique used by orthodontists) to study a group of teens to determine if they were likely to suffer from the condition. The technique will be used for earlier diagnosis for sleep apnea in teens before they become adults.
THE STUDY: The investigators studied the case histories of 590 patients between 7 and 8 years of age attending the orthodontic clinic at Case Dental School. Sixty of these patients -- a group least at risk and a group most at risk for sleep apnea -- underwent unattended in-home sleep monitoring.
WHAT IS SLEEP APNEA: Sleep apnea is a temporary suspension of breathing during sleep, which can have potentially serious consequences. People with sleep apnea can stop breathing for 10 to 30 seconds at a time, as many as 400 times a night. Most sleep apneas are the result of something blocking the passage of windpipe of the throat that brings air into the body. The tongue, tonsils, or uvula (the little piece of flesh that hangs down in the back of the throat) can all sometimes produce blockage, as can severe obesity: excess fat can block the airway. Some 12 million Americans suffer from sleep apnea, but men and those over 40 years of age are more likely to have the condition. Risk factors include heavy snoring, excess weight, high blood pressure, and any physical abnormality in the nose or throat.
WHAT ARE X-RAYS: X-rays are light waves.
The only difference between X-rays and the light that we see is that the X-rays have a higher energy level, and a shorter wavelength, making them undetectable to the human eye. Because they have so much energy, the particles that make up light, called photons, in X-rays can pass through most materials. It all depends on the size of the atoms that make up the material; larger atoms absorb X-ray photons. But smaller atoms do not, and the X-rays pass right through.
The soft tissue in the body is made of smaller atoms and doesn't absorb X-rays very well, but calcium atoms in the bones are much larger and do absorb X-rays. A camera on the other side of the patient records the patterns of X-ray light passing through the patient's body.
It's the same basic technology as that used in an ordinary camera, but X-ray light, instead of visible light, sets off the chemical reaction on the photographic plate.
How Can The World's Fisheries Be Sustainable?
According to the most recent report on the status of the world's fisheries by the United Nations Food and Agriculture Organization, fisheries supply at least 15% of the animal protein consumed by humans, provide direct and indirect employment for nearly 200 million people worldwide and generate $US85 billion annually. This same report indicates that 28% of the world's fisheries stocks are currently being overexploited or have collapsed and 52% are fully exploited.
A new study published in PLoS Biology provides the first global evaluation of how management practices influence fisheries' sustainability. The study assessed the effectiveness of the world's fisheries management regimes using evaluations from nearly 1,200 fisheries experts, analyzing these in combination with data on the sustainability of fisheries catches. The results indicate that most fisheries management regimes are lagging far behind standards set by international organizations, and that the conversion of scientific advice into policy, through a participatory and transparent process, plays the most critical role in determining the sustainability of fisheries.
"The world's fisheries are one of the most important natural assets to humankind," says lead author Camilo Mora, a Colombian researcher at Dalhousie University and the University of California San Diego. "Unfortunately, our use of the world's fisheries has been excessive and has led to the decline or collapse of many stocks."
"The consequences of overexploiting the world's fisheries are a concern not only for food security and socio-economic development but for ocean ecosystems," says Boris Worm, a professor at Dalhousie University and co-author of the paper. "We now recognize that overfishing can also lead to the erosion of biodiversity and ecosystem productivity."
"The different socioeconomic and ecological consequences associated with declining fish stocks are an international concern and several initiatives have been put forward to ensure that countries improve the way they use their marine resources," explains Mora. "Some of these initiatives include the United Nations Code of Conduct for Responsible Fisheries, the Convention on Biological Diversity, and the Millennium Ecosystem Assessment. Although these initiatives have been endorsed by most governments, a global assessment on the extent to which these ideals are actually implemented and effective remains lacking."
Mora and his colleagues analyzed a set of attributes upon which country-level fisheries could be evaluated. They pinpointed six parameters, including the scientific quality of management recommendations, the transparency of converting recommendations into policy, the enforcement of policies, the influence of subsidies, fishing effort, and the extent of fishing by foreign entities.
To quantify those attributes the researchers developed a questionnaire designed to elicit worst- to best-case answers. The survey was translated into five languages and distributed to over 13,000 fisheries experts around the world. Nearly 1,200 evaluations were used in the study. The responses of the surveyed experts were compared to, and found to be in accordance with, empirical data, supporting the validity of the data obtained in the study.
The results of this global survey showed that 7% of all coastal states carry out rigorous scientific assessment for the generation of management policies, 1.4% also have a participatory and transparent process to convert scientific recommendations into policy, and less than 1% also implement mechanisms to ensure the compliance with regulations. No one country was additionally free of the effects of excess fishing capacity, subsidies or access to foreign fishing.
"Perhaps the most striking result of our survey was that not a single country in the world was consistently good with respect to all these management attributes. So which countries are doing well and which are not is a question whose answer depends on the specific attribute you are looking at," says Mora.
The results of the study show that wealthier countries, though they have predominantly better science and enforcement capabilities, face the negative repercussions of excessive subsidies and larger fishing capacity, which have resulted largely from increased modernization of national fleets. In contrast, poorer countries largely lacked robust science and enforcement capabilities and although these nations have less fishing capacity nationally, they disproportionally sold fishing rights to nations that did. The study showed that in 33% of the coastal states classified as low-income (commonly countries in Africa and Oceania) most fishing is carried out by foreign fleets from either the European Union, South Korea, Japan, China, Taiwan or the United States.
The only attribute in which poorer and wealthier countries overlapped significantly was their limited ability to convert scientific recommendations into policy. The mechanism for this pattern, however, was different. Poor countries reportedly struggle with the effects of corruption while wealthier countries often encounter more political or economical pressures.
For the second part of the study, Mora and his colleagues combined the database on management effectiveness with a recently developed index to assess the probability that the catch of a particular country is sustainable or not. This part of the study showed that out of several attributes analysed, the transparency with which scientific recommendations are turned into policy plays the strongest role in the fate of fisheries sustainability.
"Transparent policy-making is at the centre of the entire process," explains co-author Marta Coll, at the Institut de Ciènces del Mar in Spain. "If this is heavily influenced by political pressures or corruption, it is unlikely that good scientific advice will ever be translated into proper regulations. Similarly, authoritarianism in this process is likely to reduce compliance with the resulting policies."
"This study provided us with a look at both sides of the coin," says Andrew Rosenberg at the University of New Hampshire, who was not involved in the study. "On one hand, it reminds us of the difficult challenges facing fisheries management globally in protecting critical natural resources from overexploitation. On the other hand it delivers a message of hope that when policy-making is transparent, participatory, and based on science, things can improve."
Funding to CM, RAM, and BW was provided by the Sloan Foundation through the Future of Marine Animal Populations Project. KJG holds a Royal Society-Wolfson Research Merit Award. Funding to RUS was provided by the Pew Fellowship for Marine Conservation. Funding to DZ, RUS, and RW was provided by the Pew Charitable Trust, Philadelphia through the Sea Around Us Project. Funding to MC was provided by the European Community's Seventh Framework Programme FP7/2007-2013 under grant agreement #GA-2008-219265 for the implementation of ECOFUN Project. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
A new study published in PLoS Biology provides the first global evaluation of how management practices influence fisheries' sustainability. The study assessed the effectiveness of the world's fisheries management regimes using evaluations from nearly 1,200 fisheries experts, analyzing these in combination with data on the sustainability of fisheries catches. The results indicate that most fisheries management regimes are lagging far behind standards set by international organizations, and that the conversion of scientific advice into policy, through a participatory and transparent process, plays the most critical role in determining the sustainability of fisheries.
"The world's fisheries are one of the most important natural assets to humankind," says lead author Camilo Mora, a Colombian researcher at Dalhousie University and the University of California San Diego. "Unfortunately, our use of the world's fisheries has been excessive and has led to the decline or collapse of many stocks."
"The consequences of overexploiting the world's fisheries are a concern not only for food security and socio-economic development but for ocean ecosystems," says Boris Worm, a professor at Dalhousie University and co-author of the paper. "We now recognize that overfishing can also lead to the erosion of biodiversity and ecosystem productivity."
"The different socioeconomic and ecological consequences associated with declining fish stocks are an international concern and several initiatives have been put forward to ensure that countries improve the way they use their marine resources," explains Mora. "Some of these initiatives include the United Nations Code of Conduct for Responsible Fisheries, the Convention on Biological Diversity, and the Millennium Ecosystem Assessment. Although these initiatives have been endorsed by most governments, a global assessment on the extent to which these ideals are actually implemented and effective remains lacking."
Mora and his colleagues analyzed a set of attributes upon which country-level fisheries could be evaluated. They pinpointed six parameters, including the scientific quality of management recommendations, the transparency of converting recommendations into policy, the enforcement of policies, the influence of subsidies, fishing effort, and the extent of fishing by foreign entities.
To quantify those attributes the researchers developed a questionnaire designed to elicit worst- to best-case answers. The survey was translated into five languages and distributed to over 13,000 fisheries experts around the world. Nearly 1,200 evaluations were used in the study. The responses of the surveyed experts were compared to, and found to be in accordance with, empirical data, supporting the validity of the data obtained in the study.
The results of this global survey showed that 7% of all coastal states carry out rigorous scientific assessment for the generation of management policies, 1.4% also have a participatory and transparent process to convert scientific recommendations into policy, and less than 1% also implement mechanisms to ensure the compliance with regulations. No one country was additionally free of the effects of excess fishing capacity, subsidies or access to foreign fishing.
"Perhaps the most striking result of our survey was that not a single country in the world was consistently good with respect to all these management attributes. So which countries are doing well and which are not is a question whose answer depends on the specific attribute you are looking at," says Mora.
The results of the study show that wealthier countries, though they have predominantly better science and enforcement capabilities, face the negative repercussions of excessive subsidies and larger fishing capacity, which have resulted largely from increased modernization of national fleets. In contrast, poorer countries largely lacked robust science and enforcement capabilities and although these nations have less fishing capacity nationally, they disproportionally sold fishing rights to nations that did. The study showed that in 33% of the coastal states classified as low-income (commonly countries in Africa and Oceania) most fishing is carried out by foreign fleets from either the European Union, South Korea, Japan, China, Taiwan or the United States.
The only attribute in which poorer and wealthier countries overlapped significantly was their limited ability to convert scientific recommendations into policy. The mechanism for this pattern, however, was different. Poor countries reportedly struggle with the effects of corruption while wealthier countries often encounter more political or economical pressures.
For the second part of the study, Mora and his colleagues combined the database on management effectiveness with a recently developed index to assess the probability that the catch of a particular country is sustainable or not. This part of the study showed that out of several attributes analysed, the transparency with which scientific recommendations are turned into policy plays the strongest role in the fate of fisheries sustainability.
"Transparent policy-making is at the centre of the entire process," explains co-author Marta Coll, at the Institut de Ciènces del Mar in Spain. "If this is heavily influenced by political pressures or corruption, it is unlikely that good scientific advice will ever be translated into proper regulations. Similarly, authoritarianism in this process is likely to reduce compliance with the resulting policies."
"This study provided us with a look at both sides of the coin," says Andrew Rosenberg at the University of New Hampshire, who was not involved in the study. "On one hand, it reminds us of the difficult challenges facing fisheries management globally in protecting critical natural resources from overexploitation. On the other hand it delivers a message of hope that when policy-making is transparent, participatory, and based on science, things can improve."
Funding to CM, RAM, and BW was provided by the Sloan Foundation through the Future of Marine Animal Populations Project. KJG holds a Royal Society-Wolfson Research Merit Award. Funding to RUS was provided by the Pew Fellowship for Marine Conservation. Funding to DZ, RUS, and RW was provided by the Pew Charitable Trust, Philadelphia through the Sea Around Us Project. Funding to MC was provided by the European Community's Seventh Framework Programme FP7/2007-2013 under grant agreement #GA-2008-219265 for the implementation of ECOFUN Project. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Close Relationship Between Past Warming And Sea-level Rise
A team from the National Oceanography Centre, Southampton (NOCS), along with colleagues from Tübingen (Germany) and Bristol presents a novel continuous reconstruction of sea level fluctuations over the last 520 thousand years. Comparison of this record with data on global climate and carbon dioxide (CO2) levels from Antarctic ice cores suggests that even stabilisation at today's CO2 levels may commit us to sea-level rise over the next couple of millennia, to a level much higher than long-term projections from the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC).
Little is known about the total amount of possible sea-level rise in equilibrium with a given amount of global warming. This is because the melting of ice sheets is slow, even when temperature rises rapidly. As a consequence, current predictions of sea-level rise for the next century consider only the amount of ice sheet melt that will occur until that time. The total amount of ice sheet melting that will occur over millennia, given the current climate trends, remains poorly understood.
The new record reveals a systematic equilibrium relationship between global temperature and CO2 concentrations and sea-level changes over the last five glacial cycles. Projection of this relationship to today's CO2 concentrations results in a sea-level at 25 (±5) metres above the present. This is in close agreement with independent sea-level data from the Middle Pliocene epoch, 3-3.5 million years ago, when atmospheric CO2 concentrations were similar to the present-day value. This suggests that the identified relationship accurately records the fundamental long-term equilibrium behaviour of the climate system over the last 3.5 Million years.
Lead author Professor Eelco Rohling of the University of Southampton's School of Ocean and Earth Science based at NOCS, said: "Let's assume that our observed natural relationship between CO2 and temperature, and sea level, offers a reasonable 'model' for a future with sustained global warming. Then our result gives a statistically sound expectation of a potential total long-term sea-level rise. Even if we would curb all CO2 emissions today, and stabilise at the modern level (387 parts per million by volume), then our natural relationship suggests that sea level would continue to rise to about 25 m above the present. That is, it would rise to a level similar to that measured for the Middle Pliocene."
Project partners Professor Michal Kucera (University of Tübingen) and Dr Mark Siddall (University of Bristol), add: "We emphasise that such equilibration of sea level would take several thousands of years. But one still has to worry about the large difference between the inferred high equilibrium sea level and the level where sea level actually stands today. Recent geological history shows that times with similarly strong disequilibria commonly saw pulses of very rapid sea-level adjustment, at rates of 1-2 metres per century or higher."
The new study's projection of long-term sea-level change, based on the natural relationship of the last 0.5 to 3.5 million years, differs considerably from the IPCC's model-based long-term projection of +7 m. The discrepancy cannot be easily explained, and new work is needed to ensure that the 'gap is closed'.
The observed relationships from the recent geological past can form a test-bed or reality-check for models, to help them achieve improved future projections.
Little is known about the total amount of possible sea-level rise in equilibrium with a given amount of global warming. This is because the melting of ice sheets is slow, even when temperature rises rapidly. As a consequence, current predictions of sea-level rise for the next century consider only the amount of ice sheet melt that will occur until that time. The total amount of ice sheet melting that will occur over millennia, given the current climate trends, remains poorly understood.
The new record reveals a systematic equilibrium relationship between global temperature and CO2 concentrations and sea-level changes over the last five glacial cycles. Projection of this relationship to today's CO2 concentrations results in a sea-level at 25 (±5) metres above the present. This is in close agreement with independent sea-level data from the Middle Pliocene epoch, 3-3.5 million years ago, when atmospheric CO2 concentrations were similar to the present-day value. This suggests that the identified relationship accurately records the fundamental long-term equilibrium behaviour of the climate system over the last 3.5 Million years.
Lead author Professor Eelco Rohling of the University of Southampton's School of Ocean and Earth Science based at NOCS, said: "Let's assume that our observed natural relationship between CO2 and temperature, and sea level, offers a reasonable 'model' for a future with sustained global warming. Then our result gives a statistically sound expectation of a potential total long-term sea-level rise. Even if we would curb all CO2 emissions today, and stabilise at the modern level (387 parts per million by volume), then our natural relationship suggests that sea level would continue to rise to about 25 m above the present. That is, it would rise to a level similar to that measured for the Middle Pliocene."
Project partners Professor Michal Kucera (University of Tübingen) and Dr Mark Siddall (University of Bristol), add: "We emphasise that such equilibration of sea level would take several thousands of years. But one still has to worry about the large difference between the inferred high equilibrium sea level and the level where sea level actually stands today. Recent geological history shows that times with similarly strong disequilibria commonly saw pulses of very rapid sea-level adjustment, at rates of 1-2 metres per century or higher."
The new study's projection of long-term sea-level change, based on the natural relationship of the last 0.5 to 3.5 million years, differs considerably from the IPCC's model-based long-term projection of +7 m. The discrepancy cannot be easily explained, and new work is needed to ensure that the 'gap is closed'.
The observed relationships from the recent geological past can form a test-bed or reality-check for models, to help them achieve improved future projections.
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