We spend a third of our lives asleep, but sleep researchers still don't know why. Some researchers regard sleep as one of the greatest unsolved mysteries of science, even though all animals do it in one form or another.
"Theories range from brain 'maintenance'--including memory consolidation and pruning--to reversing damage from oxidative stress suffered while awake, to promoting longevity," says a statement released this week by the University of California in Los Angeles. "None of these theories are well established, and many are mutually exclusive."
A new analysis by Jerome Siegel, UCLA professor of psychiatry and director of the Center for Sleep Research at the Semel Institute for Neuroscience and Human Behavior at UCLA and the Sepulveda Veterans Affairs Medical Center, has concluded that sleep's primary function is to increase animals' efficiency and minimize their risk by regulating the duration and timing of their behavior, the UCLA statement said.
The research appears in the online edition of the journal Nature Reviews Neuroscience.
"Sleep has normally been viewed as something negative for survival because sleeping animals may be vulnerable to predation and they can't perform the behaviors that ensure survival," Siegel said. These behaviors include eating, procreating, caring for family members, monitoring the environment for danger and scouting for prey.
"So it's been thought that sleep must serve some as-yet unidentified physiological or neural function that can't be accomplished when animals are awake," he said.
But after monitoring the sleep times of a broad range of animals--from the platypus and the walrus to the echidna--the team led by Siegel concluded that sleep itself is highly adaptive, "much like the inactive states seen in a wide range of species, starting with plants and simple microorganisms."
"These species have dormant states as opposed to sleep--even though in many cases they do not have nervous systems," UCLA noted.
That challenges the idea that sleep is for the brain, Siegel said.
"We see sleep as lying on a continuum that ranges from these dormant states like torpor and hibernation, on to periods of continuous activity without any sleep, such as during migration, where birds can fly for days on end without stopping," he said.
Hibernation is one example of an activity that regulates behavior for survival. A small animal can't migrate to a warmer climate in winter, Siegel said. "So it hibernates, effectively cutting its energy consumption and thus its need for food, remaining secure from predators by burrowing underground."
Sleep duration, then, is determined in each species by the time requirements of eating, the cost-benefit relations between activity and risk, migration needs, care of young, and other factors, the research team said.
"However, unlike hibernation and torpor," Siegel said, "sleep is rapidly reversible--that is, animals can wake up quickly, a unique mammalian adaptation that allows for a relatively quick response to sensory signals."
Humans fit into this analysis as well.
What is most remarkable about sleep, according to Siegel, is not the unresponsiveness or vulnerability it creates but rather the ability to reduce body and brain metabolism while still allowing a high level of responsiveness to the environment.
"The often cited example is that of a parent arousing at a baby's whimper but sleeping through a thunderstorm. That dramatizes the ability of the sleeping human brain to continuously process sensory signals and trigger complete awakening to significant stimuli within a few hundred milliseconds."
In humans, the brain constitutes, on average, just 2 percent of total body weight but consumes 20 percent of the energy used during quiet waking, so these savings have considerable adaptive significance, UCLA said.
"Besides conserving energy, sleep also invokes survival benefits for humans."
Besides conserving energy, sleep also invokes survival benefits for humans, including, according to Siegel, "a reduced risk of injury, reduced resource consumption and, from an evolutionary standpoint, reduced risk of detection by predators."
"This Darwinian perspective can explain age-related changes in human sleep patterns as well," he said.
"We sleep more deeply when we are young, because we have a high metabolic rate that is greatly reduced during sleep, but also because there are people to protect us.
"Our sleep patterns change when we are older, though, because that metabolic rate reduces and we are now the ones doing the alerting and protecting from dangers."
Tuesday, October 26, 2010
Over 700 Insects found encased in amber!
THE NEW YORK TIMES
Observitory
An amber excavation in western India has led to the discovery of more than 700 ancient insects, arachnids and crustaceans, and many plant, floral and fungal remains.
“We have at least 100 new species of insects, possibly many more,” said David Grimaldi, one of the study’s authors and an entomologist at the American Museum of Natural History in New York.
The specimens are estimated to be about 50 million to 53 million years old. The area was then a lush tropical rain forest, similar to the forests found today in Borneo and other parts of Southeast Asia.
Researchers from the United States, Germany and India reported these findings in the Proceedings of the National Academy of Sciences. They found that there were similarities between the new specimens and fossils found in Mexico and Central America.
Dr. Grimaldi said that about 100 million years ago, India, Madagascar, the Seychelles and Sri Lanka broke off from Gondwana, a landmass that also encompassed land that became four present-day continents: Africa, Antarctica, Australia and South America.
After separating from present-day Africa, India began drifting. Eventually, after about 50 million years, India collided with Asia, creating the Himalayas.
“If anything, we thought the fossils would be unique or have obvious connections to Africa or Madagascar,” Dr. Grimaldi said. “This suggests that India was not as isolated at that time period as we thought, and that it’s possible there were other geologic scenarios.”
In addition, the researchers found mammalian remains that need further study, including those of bats, primates and primitive rabbits.
The plant specimens also need to be looked at more closely by a paleobotanist, who can determine how many previously unknown species were found.
Observitory
An amber excavation in western India has led to the discovery of more than 700 ancient insects, arachnids and crustaceans, and many plant, floral and fungal remains.
“We have at least 100 new species of insects, possibly many more,” said David Grimaldi, one of the study’s authors and an entomologist at the American Museum of Natural History in New York.
The specimens are estimated to be about 50 million to 53 million years old. The area was then a lush tropical rain forest, similar to the forests found today in Borneo and other parts of Southeast Asia.
Researchers from the United States, Germany and India reported these findings in the Proceedings of the National Academy of Sciences. They found that there were similarities between the new specimens and fossils found in Mexico and Central America.
Dr. Grimaldi said that about 100 million years ago, India, Madagascar, the Seychelles and Sri Lanka broke off from Gondwana, a landmass that also encompassed land that became four present-day continents: Africa, Antarctica, Australia and South America.
After separating from present-day Africa, India began drifting. Eventually, after about 50 million years, India collided with Asia, creating the Himalayas.
“If anything, we thought the fossils would be unique or have obvious connections to Africa or Madagascar,” Dr. Grimaldi said. “This suggests that India was not as isolated at that time period as we thought, and that it’s possible there were other geologic scenarios.”
In addition, the researchers found mammalian remains that need further study, including those of bats, primates and primitive rabbits.
The plant specimens also need to be looked at more closely by a paleobotanist, who can determine how many previously unknown species were found.
Shampoo, Cosmetics May Form Cancer-Causing Substance in Water Supplies
Your shampoo may seem harmless, but it could be contributing to the formation of a mysterious, cancer-causing substance, a new study says.
New research reveals that common household products such as shampoo can interact with disinfectants at U.S. wastewater treatment plants to form a little-studied class of cancer-causing substances. These substances, called nitrosamines, can end up in drinking water, experts say.
(Related: "Cocaine, Spices, Hormones Found in Drinking Water.")
Several nitrosamines, including the chemical NDMA, a focus of the new Yale study, are classified by the U.S. Environmental Protection Agency (EPA) as probable human carcinogens.
Nitrosamines form in small amounts when exposed to chloramine, the disinfectant of choice at the nation's wastewater treatment plants. The chemical—a combination of chlorine and ammonia—has been used increasingly in drinking water disinfection since the EPA set limits for better-known toxic substances that can arise from the use of chlorine, the traditional disinfectant.
Though inconclusive, the study suggests "it's entirely possible that we're producing more problems—and maybe even worse problems—with chloramines," said David Reckhow, an environmental engineer at the University of Massachusetts in Amherst who was not involved in the new study.
Cost of Beauty?
Nitrosamines are found in a wide variety of sources, including processed meats and tobacco smoke, but what sparks their formation in drinking water has long baffled scientists.
Past studies with cosmetics have hinted that substances called quaternary amines, which are also ingredients in household cleaning agents, may play a role in creating nitrosamines.
Other work has shown the drug ranitidine, a stomach acid reducer also known as Zantac, can be transformed into NDMA. But those chemicals occur in trace concentrations in wastewater, and "ranitidine itself has not been detected as far as I know," said study co-author William Mitch, a chemical engineer at Yale University. "We started to think about chemicals that are used in high concentrations in consumer products."
In search of more sources of nitrosamines, Mitch and his colleagues tested water at three treatment plants in Connecticut. The team then analyzed the relative amounts of quaternary amines and nitrosamines before and after treatment with chloramine.
They also tested four common household products, chosen at random, for chemicals that readily form nitrosamines: Suave and Pantene shampoos, Dawn dishwashing soap, and Cheer laundry detergent.
Mixed Results
The researchers found that although sewage treatment plants remove some of the quaternary amines that form NDMA, quaternary amines are used in such large quantities that some may make it through the treatment process.
For example, if 80 percent of people in an area served by a treatment plant used a typical amount of Suave shampoo daily, that amount of shampoo would account for up to 3 percent of nitrosamines in the treated wastewater, the authors wrote. Dawn detergent created 26 times more NDMA than Suave, according to the study in the January 19 edition of the journal Environmental Science & Technology.
Some products, such as Cheer laundry detergent and Pantene shampoo, did not form nitrosamines. And the highly preliminary results do not indicate whether other brands of household products would.
Mitch said that while some quaternary amines might be removed during wastewater treatment, others might be biologically transformed into tertiary amines, which yield even higher amounts of nitrosamines.
"The problem is that we don't know because many of these materials are polymeric, and current analytical techniques are not geared to measure polymer concentrations," he said. Polymers are molecules made up of chains of simple, repeated units.
"So at this point, it's a suggestion, because we cannot measure polymeric quaternary amines to demonstrate a link."
Don't Pee in the Pool?
Mitch said the combination of disinfectants and quaternary amines can occur in places other than treatment plants—when different household cleaners are combined, for instance, or in swimming pools.
"In fact, we measured nitrosamine concentrations in swimming pools, and the precursors are either consumer products or human waste," he said, referring to the fact that people sometimes urinate in pools. Those results were published in 2008 in the journal Environmental Science & Technology.
Yet no regulations exist so far in the United States—the University of Massachusetts' Reckhow said it's not unusual for regulations to lag behind scientific discovery.
"There’s no way of getting around that, end even the science isn’t really sure" about the consequences of combining chloramination at treatment plants with household products, he said.
Still, the work represents an important step, said Susan Richardson, a research chemist with the National Exposure Research Laboratory in Athens, Georgia, who was not involved in the research.
"The more we understand the sources of nitrosamines and other hazardous chemicals," Richardson said by email, "the more we can find ways to minimize our exposure to them."
New research reveals that common household products such as shampoo can interact with disinfectants at U.S. wastewater treatment plants to form a little-studied class of cancer-causing substances. These substances, called nitrosamines, can end up in drinking water, experts say.
(Related: "Cocaine, Spices, Hormones Found in Drinking Water.")
Several nitrosamines, including the chemical NDMA, a focus of the new Yale study, are classified by the U.S. Environmental Protection Agency (EPA) as probable human carcinogens.
Nitrosamines form in small amounts when exposed to chloramine, the disinfectant of choice at the nation's wastewater treatment plants. The chemical—a combination of chlorine and ammonia—has been used increasingly in drinking water disinfection since the EPA set limits for better-known toxic substances that can arise from the use of chlorine, the traditional disinfectant.
Though inconclusive, the study suggests "it's entirely possible that we're producing more problems—and maybe even worse problems—with chloramines," said David Reckhow, an environmental engineer at the University of Massachusetts in Amherst who was not involved in the new study.
Cost of Beauty?
Nitrosamines are found in a wide variety of sources, including processed meats and tobacco smoke, but what sparks their formation in drinking water has long baffled scientists.
Past studies with cosmetics have hinted that substances called quaternary amines, which are also ingredients in household cleaning agents, may play a role in creating nitrosamines.
Other work has shown the drug ranitidine, a stomach acid reducer also known as Zantac, can be transformed into NDMA. But those chemicals occur in trace concentrations in wastewater, and "ranitidine itself has not been detected as far as I know," said study co-author William Mitch, a chemical engineer at Yale University. "We started to think about chemicals that are used in high concentrations in consumer products."
In search of more sources of nitrosamines, Mitch and his colleagues tested water at three treatment plants in Connecticut. The team then analyzed the relative amounts of quaternary amines and nitrosamines before and after treatment with chloramine.
They also tested four common household products, chosen at random, for chemicals that readily form nitrosamines: Suave and Pantene shampoos, Dawn dishwashing soap, and Cheer laundry detergent.
Mixed Results
The researchers found that although sewage treatment plants remove some of the quaternary amines that form NDMA, quaternary amines are used in such large quantities that some may make it through the treatment process.
For example, if 80 percent of people in an area served by a treatment plant used a typical amount of Suave shampoo daily, that amount of shampoo would account for up to 3 percent of nitrosamines in the treated wastewater, the authors wrote. Dawn detergent created 26 times more NDMA than Suave, according to the study in the January 19 edition of the journal Environmental Science & Technology.
Some products, such as Cheer laundry detergent and Pantene shampoo, did not form nitrosamines. And the highly preliminary results do not indicate whether other brands of household products would.
Mitch said that while some quaternary amines might be removed during wastewater treatment, others might be biologically transformed into tertiary amines, which yield even higher amounts of nitrosamines.
"The problem is that we don't know because many of these materials are polymeric, and current analytical techniques are not geared to measure polymer concentrations," he said. Polymers are molecules made up of chains of simple, repeated units.
"So at this point, it's a suggestion, because we cannot measure polymeric quaternary amines to demonstrate a link."
Don't Pee in the Pool?
Mitch said the combination of disinfectants and quaternary amines can occur in places other than treatment plants—when different household cleaners are combined, for instance, or in swimming pools.
"In fact, we measured nitrosamine concentrations in swimming pools, and the precursors are either consumer products or human waste," he said, referring to the fact that people sometimes urinate in pools. Those results were published in 2008 in the journal Environmental Science & Technology.
Yet no regulations exist so far in the United States—the University of Massachusetts' Reckhow said it's not unusual for regulations to lag behind scientific discovery.
"There’s no way of getting around that, end even the science isn’t really sure" about the consequences of combining chloramination at treatment plants with household products, he said.
Still, the work represents an important step, said Susan Richardson, a research chemist with the National Exposure Research Laboratory in Athens, Georgia, who was not involved in the research.
"The more we understand the sources of nitrosamines and other hazardous chemicals," Richardson said by email, "the more we can find ways to minimize our exposure to them."
Access Codes
Hi there fellow Blog-Goers! Here's the access codes and e-mails
sciencedebatingdbs@gmail.com
the username is ScienceDebatingDBS and the password is elementary
Magic ,eh here's a Science link to get you started;
http://www.pbs.org/wnet/nature/episodes/a-murder-of-crows/full-episode/5977/
sciencedebatingdbs@gmail.com
the username is ScienceDebatingDBS and the password is elementary
Magic ,eh here's a Science link to get you started;
http://www.pbs.org/wnet/nature/episodes/a-murder-of-crows/full-episode/5977/
Water Discovered on an Asteroid
http://news.nationalgeographic.com/news/2010/04/100428-asteroid-water-first-ice-frost-themis/
24 Themis has a frosty coating mixed with organic material, study says.
Published April 28, 2010
Water has been spotted on an orbiting asteroid for the first time, according to a new study of a space rock that appears to be coated with frost.
What's more, the frost seems to be mixed with carbon-bearing material, according to results from two independent teams studying the asteroid, which is known as 24 Themis.
"We report the first detection of water ice and of organic molecules on an asteroid, and they are both on the same asteroid," said Humberto Campins of the University of Central Florida, leader of one of the teams.
Both teams used NASA's Infrared Telescope Facility in Hawaii to watch how sunlight reflected off the asteroid at different wavelengths, revealing the watery signature.
A closer look at similar asteroids, perhaps during a proposed NASA mission, could help reveal whether the water we drink—and maybe even the building blocks of life—were delivered to Earth by impacting space rocks. (See "Comet Swarm Delivered Earth's Oceans?")
Asteroid Water Ice Exposed by "Impact Gardening"?
Asteroids are believed to be the leftovers of planet formation, with compositions that have remained almost pristine for 4.6 billion years.
The asteroid 24 Themis orbits about x million miles (480 million kilometers) from the sun. It's one of the largest asteroids in the main asteroid belt, which lies between the orbits of Mars and Jupiter. (Explore an interactive solar system).
Unlike comets, which originate from beyond the orbit of Neptune, asteroids are thought to be relatively dry, since they orbit much closer to the sun.
But previous theories have suggested that ice could still exist in the main asteroid belt if it's buried below the surfaces of the space rocks. (See asteroid and comet pictures.)
In fact, two nearby "relatives" of 24 Themis are members of a strange group called main-belt comets, which are known to leave dust tails that may be fueled by water ice sublimating, or turning directly from a solid into a gas. (Related: "Strange 'Comet' May Be Asteroid Collision Debris.")
The discovery of frost on 24 Themis means that the asteroid "represents a 'living' window into the early solar system in the form of ice that, according to conventional wisdom, should have been long gone," astrophysicist Henry Hsieh, of Queen's University Belfast, wrote in a commentary on the new study.
On 24 Themis, the frost might be coming from subsurface ice that sublimates when sunlight warms up the asteroid, sending vapor to the surface. The gas then recondenses on the surface when darkness falls and temperatures dip, study author Campins said.
Or micrometeorites may practice "impact gardening," churning the surface enough to gradually uncover a layer of preserved subsurface ice.
Or the answer may be something else entirely, Campins admits: "One of the fun things about having so little information is how much one can speculate," he said.
Asteroids May Have Brought Water to Earth
More data on asteroid composition could arrive as early as June, when the Japanese spacecraft Hayabusa returns to Earth potentially carrying the first sample taken directly from an asteroid. (Read about NASA's plans to send astronauts to an asteroid.)
Hayabusa landed on the asteroid Itokawa in 2005. Although the craft failed to collect any formal samples, scientists think some dust from the space rock's surface might have accidentally gotten into the sampling chamber.
Meanwhile, a proposed NASA mission dubbed the Origins Spectral Interpretation Resource Identification Security-Regolith Explorer, or OSIRIS-REx, could bring back a sample from an asteroid called RQ36.
"It so happens that this main target of OSIRIS-REx is an asteroid of the same classification as 24 Themis," Campins said, which means a sample from RQ36 might contain water like that seen on 24 Themis.
By some accounts, Earth should have been too hot in its early days to have retained any of its original water. This has led some scientists to suspect our oceans were delivered by a barrage of asteroids or comets once the planet had cooled.
Matching the chemical qualities of the asteroid's water with Earthly H2O could solve the mystery. And if the OSIRIS-REx sample also has organics, it could bolster theories that space rocks delivered the starting materials for life.
"It could be that the composition of this nearby object is also like 24 Themis," Campins said of RQ36. "So we might be able to sample the primitive organic molecules that could have been the building blocks that [enabled] life to arrive on Earth by a near-Earth asteroid."
The asteroid-ice discovery is described in this week's issue of the journal Nature.
What's more, the frost seems to be mixed with carbon-bearing material, according to results from two independent teams studying the asteroid, which is known as 24 Themis.
"We report the first detection of water ice and of organic molecules on an asteroid, and they are both on the same asteroid," said Humberto Campins of the University of Central Florida, leader of one of the teams.
Both teams used NASA's Infrared Telescope Facility in Hawaii to watch how sunlight reflected off the asteroid at different wavelengths, revealing the watery signature.
A closer look at similar asteroids, perhaps during a proposed NASA mission, could help reveal whether the water we drink—and maybe even the building blocks of life—were delivered to Earth by impacting space rocks. (See "Comet Swarm Delivered Earth's Oceans?")
Asteroid Water Ice Exposed by "Impact Gardening"?
Asteroids are believed to be the leftovers of planet formation, with compositions that have remained almost pristine for 4.6 billion years.
The asteroid 24 Themis orbits about x million miles (480 million kilometers) from the sun. It's one of the largest asteroids in the main asteroid belt, which lies between the orbits of Mars and Jupiter. (Explore an interactive solar system).
Unlike comets, which originate from beyond the orbit of Neptune, asteroids are thought to be relatively dry, since they orbit much closer to the sun.
But previous theories have suggested that ice could still exist in the main asteroid belt if it's buried below the surfaces of the space rocks. (See asteroid and comet pictures.)
In fact, two nearby "relatives" of 24 Themis are members of a strange group called main-belt comets, which are known to leave dust tails that may be fueled by water ice sublimating, or turning directly from a solid into a gas. (Related: "Strange 'Comet' May Be Asteroid Collision Debris.")
The discovery of frost on 24 Themis means that the asteroid "represents a 'living' window into the early solar system in the form of ice that, according to conventional wisdom, should have been long gone," astrophysicist Henry Hsieh, of Queen's University Belfast, wrote in a commentary on the new study.
On 24 Themis, the frost might be coming from subsurface ice that sublimates when sunlight warms up the asteroid, sending vapor to the surface. The gas then recondenses on the surface when darkness falls and temperatures dip, study author Campins said.
Or micrometeorites may practice "impact gardening," churning the surface enough to gradually uncover a layer of preserved subsurface ice.
Or the answer may be something else entirely, Campins admits: "One of the fun things about having so little information is how much one can speculate," he said.
Asteroids May Have Brought Water to Earth
More data on asteroid composition could arrive as early as June, when the Japanese spacecraft Hayabusa returns to Earth potentially carrying the first sample taken directly from an asteroid. (Read about NASA's plans to send astronauts to an asteroid.)
Hayabusa landed on the asteroid Itokawa in 2005. Although the craft failed to collect any formal samples, scientists think some dust from the space rock's surface might have accidentally gotten into the sampling chamber.
Meanwhile, a proposed NASA mission dubbed the Origins Spectral Interpretation Resource Identification Security-Regolith Explorer, or OSIRIS-REx, could bring back a sample from an asteroid called RQ36.
"It so happens that this main target of OSIRIS-REx is an asteroid of the same classification as 24 Themis," Campins said, which means a sample from RQ36 might contain water like that seen on 24 Themis.
By some accounts, Earth should have been too hot in its early days to have retained any of its original water. This has led some scientists to suspect our oceans were delivered by a barrage of asteroids or comets once the planet had cooled.
Matching the chemical qualities of the asteroid's water with Earthly H2O could solve the mystery. And if the OSIRIS-REx sample also has organics, it could bolster theories that space rocks delivered the starting materials for life.
"It could be that the composition of this nearby object is also like 24 Themis," Campins said of RQ36. "So we might be able to sample the primitive organic molecules that could have been the building blocks that [enabled] life to arrive on Earth by a near-Earth asteroid."
The asteroid-ice discovery is described in this week's issue of the journal Nature.
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