Railing Air-Less

Vacuum Tube Train: A 4,000-mph magnetically levitated train could allow you to have lunch in Manhattan and still get to London in time for the theater, despite the 5-hour time difference. It’s not impossible: Norway has studied neutrally buoyant tunnels (concluding that they’re feasible, though expensive), and Shanghai is running maglev trains to its airport. But supersonic speeds require another critical step: eliminating the air—and therefore air friction—from the train’s path. A vacuum would also save the tunnel from the destructive effects of a sonic boom, which, unchecked, could potentially rip the tunnel apart.

What: Submerged OCEANIC tunnel and supersonic train

WHERE: New York – LondonCost: $88 billion – $175 billion

Crux: Neutrally buoyant vacuum tunnel submerged 150 to 300 feet beneath the Atlantic's surface and anchored to the seafloor, through which zips a magnetically levitated train at up to 4,000 mph.The idea is as wondrous as it is audacious:

Get on a train at New York City's Penn Station and hit Paris, London or Brussels just an hour later. "From an engineering point of view there are no serious stumbling blocks," says Ernst Frankel, retired professor of ocean engineering at MIT.

As envisioned by Frankel and Frank Davidson, a former MIT researcher and early member of the first formal English Channel Tunnel study group, sections of neutrally buoyant tunnel submerged 150 to 300 feet beneath the surface of the Atlantic, then anchored to the seafloor–thereby avoiding the high pressures of the deep ocean. Then air would be pumped out, creating a vacuum, and alternating magnetic pulses would propel a magnetically levitated train capable of speeds up to 4,000 mph across the pond in an hour. As Frankel and Davidson say, it's doable. "We lay pipes and cables across the ocean every day," says Frankel. "The

Norwegians recently investigated submerged, floating tunnels for crossing their deep fjords, and were only held back by the costs." Ah, the costs: Estimates range from $25 million to $50 million per mile. Another hurdle: safety. But Davidson believes a test case might mitigate concerns. "Maybe a tunnel across Lake Ontario would show how it reacts to dynamic conditions and give us a better understanding of the costs," he muses. "A transatlantic tunnel will be done. We just have to be as interested in it as we are in getting to the Moon."

What Happens During Sleep????

Many people think of sleep as a passive activity, but our brains are actually very active during sleep. Moreover, sleep affects our daily functioning and our physical and mental health in many ways.

Nerve-signaling chemicals called neurotransmitters control whether we are asleep or awake by acting on different groups of nerve cells, or neurons, in the brain. Neurons in the brainstem, which connects the brain with the spinal cord, produce neurotransmitters such as serotonin and norepinephrine that keep some parts of the brain active while we are awake. Other neurons at the base of the brain begin signaling when we fall asleep. These neurons appear to "switch off" the signals that keep us awake. Research also suggests that a chemical called adenosine builds up in our blood while we are awake and causes drowsiness. This chemical gradually breaks down while we sleep.

Five phases of sleep
During sleep, we usually pass through five phases of sleep: stages 1, 2, 3, 4, and REM (rapid eye movement) sleep. These stages progress in a cycle from stage 1 to REM sleep, then the cycle starts over again with stage 1. We spend almost 50 percent of our total sleep time in stage 2 sleep, about 20 percent in REM sleep, and the remaining 30 percent in the other stages. Infants, by contrast, spend about half of their sleep time in REM sleep.

• Stage 1
  During stage 1, which is light sleep, we drift in and out of sleep and can be awakened easily. Our eyes move very slowly and muscle activity slows. People awakened from stage 1 sleep often remember fragmented visual images. Many also experience sudden muscle contractions called hypnic myoclonia, often preceded by a sensation of starting to fall. These sudden movements are similar to the "jump" we make when startled.
  
  
• Stage 2
  When we enter stage 2 sleep, our eye movements stop and our brain waves (fluctuations of electrical activity that can be measured by electrodes) become slower, with occasional bursts of rapid waves called sleep spindles.
  
  
• Stage 3
  In stage 3, extremely slow brain waves called delta waves begin to appear, interspersed with smaller, faster waves.
  
  
• Stage 4
  By stage 4, the brain produces delta waves almost exclusively. It is very difficult to wake someone during stages 3 and 4, which together are called deep sleep . There is no eye movement or muscle activity. People awakened during deep sleep do not adjust immediately and often feel groggy and disoriented for several minutes after they wake up. Some children experience bedwetting, night terrors, or sleepwalking during deep sleep.
  
  
• REM sleep
  When we switch into REM sleep, our breathing becomes more rapid, irregular, and shallow, our eyes jerk rapidly in various directions, and our limb muscles become temporarily paralyzed. Our heart rate increases, our blood pressure rises, and males develop penile erections. When people awaken during REM sleep, they often describe bizarre and illogical tales - dreams.

  The first REM sleep period usually occurs about 70 to 90 minutes after we fall asleep. A complete sleep cycle takes 90 to 110 minutes on average. The first sleep cycles each night contain relatively short REM periods and long periods of deep sleep. As the night progresses, REM sleep periods increase in length while deep sleep decreases. By morning, people spend nearly all their sleep time in stages 1, 2, and REM.

People awakened after sleeping more than a few minutes are usually unable to recall the last few minutes before they fell asleep. This sleep-related form of amnesia is the reason people often forget telephone calls or conversations they've had in the middle of the night. It also explains why we often do not remember our alarms ringing in the morning if we go right back to sleep after turning them off.

Dreaming and REM sleep
We typically spend more than 2 hours each night dreaming. Scientists do not know much about how or why we dream. Sigmund Freud, who greatly influenced the field of psychology, believed dreaming was a "safety valve" for unconscious desires. The strange, illogical experiences we call dreams almost always occur during REM sleep.

REM sleep begins with signals from an area at the base of the brain called the pons These signals travel to a brain region called the thalamus , which relays them to the cerebral cortex - the outer layer of the brain that is responsible for learning, thinking, and organizing information. The pons also sends signals that shut off neurons in the spinal cord, causing temporary paralysis of the limb muscles. If something interferes with this paralysis, people will begin to physically "act out" their dreams - a rare, dangerous problem called REM sleep behavior disorder. A person dreaming about a ball game, for example, may run headlong into furniture or blindly strike someone sleeping nearby while trying to catch a ball in the dream.

REM sleep stimulates the brain regions used in learning. Like deep sleep, REM sleep is associated with increased production of proteins. One study found that REM sleep affects learning of certain mental skills. People taught a skill and then deprived of non-REM sleep could recall what they had learned after sleeping, while people deprived of REM sleep could not.

Sleep influenced by food, medications, chemicals, temperature
Since sleep and wakefulness are influenced by different neurotransmitter signals in the brain, foods and medicines that change the balance of these signals affect whether we feel alert or drowsy and how well we sleep. Caffeinated drinks such as coffee and drugs such as diet pills and decongestants stimulate some parts of the brain and can cause insomnia, or an inability to sleep. Many antidepressants suppress REM sleep. Heavy smokers often sleep very lightly and have reduced amounts of REM sleep. They also tend to wake up after 3 or 4 hours of sleep due to nicotine withdrawal.

Many people who suffer from insomnia try to solve the problem with alcohol - the so-called night cap. While alcohol does help people fall into light sleep, it also robs them of REM and the deeper, more restorative stages of sleep. Instead, it keeps them in the lighter stages of sleep, from which they can be awakened easily.

People lose some of the ability to regulate their body temperature during REM, so abnormally hot or cold temperatures in the environment can disrupt this stage of sleep. If our REM sleep is disrupted one night, our bodies don't follow the normal sleep cycle progression the next time we doze off. Instead, we often slip directly into REM sleep and go through extended periods of REM until we "catch up" on this stage of sleep.

People who are under anesthesia or in a coma are often said to be asleep. However, people in these conditions cannot be awakened and do not produce the complex, active brain wave patterns seen in normal sleep. Instead, their brain waves are very slow and weak, sometimes all but undetectable.

Ice created in nanoseconds by Sandia’s Z machine

aLBUQUERQUE, N.M. — Sandia’s huge Z machine, which generates temperatures hotter than the sun, has turned water to ice in nanoseconds.

However, don’t expect anything commercial just yet: the ice is hotter than the boiling point of water.

“The three phases of water as we know them — cold ice, room temperature liquid, and hot vapor — are actually only a small part of water’s repertory of states,” says Sandia researcher Daniel Dolan. “Compressing water customarily heats it. But under extreme compression, it is easier for dense water to enter its solid phase [ice] than maintain the more energetic liquid phase [water].”

Sandia is a National Nuclear Security Administration (NNSA) laboratory.

In the Z experiment, the volume of water shrank abruptly and discontinuously, consistent with the formation of almost every known form of ice except the ordinary kind, which expands. (One might wonder why this ice shrank instead of expanding, given the common experience of frozen water expanding to wreck garden hoses left out over winter. The answer is that only “ordinary” ice expands when water freezes. There are at least 11 other known forms of ice occurring at a variety of temperatures and pressures.)

“This work,” says Dolan, “is a basic science study that helps us understand materials at extreme conditions.”

But it has potential practical value. The work, which appears online March 11 in Nature Physics, was undertaken partly because phase diagrams that predict water’s state at different temperatures and pressures are not always correct — a fact worrisome to experimentalists working at extreme conditions, as well as those having to work at distances where direct measurement is impractical. For example, work reported some months ago at Z demonstrated that astronomers’ ideas about the state of water on the planet Neptune were probably incorrect.

Closer at hand, water in a glass could be cooled below freezing and remain water, in what is called a supercooled state.

Accurate knowledge of water’s behavior is potentially important for Z because the 20-million-ampere electrical pulses the accelerator sends through water compress that liquid. Ordinarily, the water acts as an insulator and as a switch. But because the machine is being refurbished with more modern and thus more powerful equipment, questions about water’s behavior at extreme conditions are of increasing interest to help avoid equipment failure for the machine or its more powerful successors, should those be built.

One unforeseen result of Dolan’s test was that the water froze so rapidly. The freezing process as it is customarily observed requires many seconds at the very least.

The answer, says Dolan, seems to be that very fast compression causes very fast freezing. At Z and also at Sandia’s nearby STAR (Shock Thermodynamic Applied Research) gas gun facility, thin water samples were compressed to pressures of 50,000-120,000 atmospheres in less than 100 nanoseconds. Under such pressures, water appears to transform to ice VII, a phase of water first discovered by Nobel laureate Percy Bridgman in the 1930s. The compressed water appeared to solidify into ice within a few nanoseconds.

Ice VII has nothing to do with ice-nine, an entirely fictional creation of author Kurt Vonnegut in his 1963 novel Cat’s Cradle. There, a few molecules of the invented substance acts as a precipitating seed to cause an extended chemical reaction that freezes almost all of Earth’s water. Ice VII, on the other hand, only stays frozen as long as it is under enormous pressure. The pressure relenting, the ice changes back to ordinary water.

Nucleating agents, of course, are often used to hasten sluggish chemical processes, such as when clouds are “seeded” with silver iodide to induce rain. Dolan already had demonstrated, as a graduate physics student at Washington State University, that water can freeze on nanosecond time scales in the presence of a nucleating agent.

However, the behavior of pure water under high pressure remained a mystery.

Sandia instruments observed the unnucleated water becoming rapidly opaque — a sign of ice formation in which water and ice coexist — as pressure increased. At the 70,000 atmosphere mark and thereafter, the water became clear, a sign that the container now held entirely ice.

“Apparently it’s virtually impossible to keep water from freezing at pressures beyond 70,000 atmospheres,” Dolan says.

For these tests, Z created the proper conditions by magnetic compression. Twenty million amperes of electricity passed through a small aluminum chamber, creating a magnetic field that isentropically compressed aluminum plates roughly 5.5 by 2 inches in cross section. This created a shockless but rapidly increasing compression across a 25-micron-deep packet of water.

The multipurpose Z machine, whose main use is to produce data to improve the safety and reliability of the US nuclear deterrent, has compressed spherical capsules of hydrogen isotopes to release neutrons — the prerequisite for controlled nuclear fusion and essentially unlimited energy for humanity.

This work is sponsored by the NNSA. Other authors on the paper are Chris Deeney (now at NNSA), and Sandians Mark Knudson and Clint Hall.

How do we manage to remember smells despite the fact that each olfactory sensory neuron only survives for about 60 days and is then replaced by a new cell?

Donald Wilson, a professor of zoology at the University of Oklahoma and co-author of the 2006 book Learning to Smell: Olfactory Perception from Neurobiology to Behavior, sniffs around for an answer.

In 2004 the Nobel Prize in Physiology or Medicine went to Linda B. Buck and Richard Axel for their research showing that there is a huge family of genes that encode proteins called olfactory receptors. Their findings, published in 1991, opened many doors toward understanding the function of the olfactory system.

One important observation was that individual olfactory sensory neurons typically express just one of those genes. Thus, signals coming from a given neuron provide information about odors that activate the specific receptor protein expressed by that cell. A single receptor protein, however, appears to bind (or recognize) many different odors. Thus, rather than having neurons that respond selectively to coffee or vanilla or Bordeaux, most individual cells (via their receptors) respond to submolecular features of the volatile chemicals coming from those objects. For example, an olfactory sensory receptor neuron may respond to a hydrocarbon chain of a particular length or a specific functional group like an alcohol or aldehyde.

This means that any given sensory neuron will respond to many different odors as long as they share a common feature. The brain (specifically, the olfactory bulb and olfactory cortex) then looks at the combination of sensory neurons activated at any given time and interprets that pattern in the context of previous patterns that have been experienced and other kinds of available information. The interpreted pattern is what you perceive as smell.

Olfactory sensory neurons, which sit in the mucus in the back of the nose and relay data into the brain via axons (fingerlike projections that transmit information out from the cell body), do not live forever. In fact, they are one of the increasingly large number of neuron types that are known to die and be replaced throughout life.

Fortunately, they do not all die at the same time. There are many thousands of olfactory sensory neurons expressing any particular olfactory receptor. When a small subset dies, the pattern of activity that the olfactory processing regions in the brain receives for a specific smell doesn't change very much. In fact, when an olfactory sensory neuron expressing a particular receptor gene dies and a new neuron expressing that same gene matures, the new neuron's axons plug in to the same group of olfactory bulb neurons that its predecessor did. This results in remarkable pattern stability over years, despite continual rewiring.

Let's imagine that on a recent holiday you tried a new wine. The odor (or bouquet, to oenophiles) of that wine is composed of dozens of different volatile chemicals, and each chemical has several submolecular features. Therefore, the wine activates a complex pattern of olfactory sensory neurons by engaging each of their olfactory receptor proteins, which recognize these different features. This pattern is processed and remembered by neural circuits in the olfactory bulb and olfactory cortex.

Several weeks later when you return home, you find the wine in your local market. Despite having replaced at least a subset of the olfactory sensory neurons that first interacted with that wine's unique odor, you are still able to recognize its aroma when you pour a glass, because the overall pattern of activity within the olfactory system remains relatively constant.

Brain Center For 'Sound Space' Identified

The findings settle a controversy in earlier studies that failed to establish the auditory region, called the planum temporale, as responsible for perceiving auditory space. Leon Y. Deouell and colleagues published their findings in the journal Neuron.
Studies by other researchers had shown that the planum temporale was activated when people were asked to perform tasks in which they located sounds in space. However, many researchers believed that the region was responsible only for intentional processing of such information. And in fact, previous studies had failed to establish that the planum temporale was responsible for automatic, nonintentional representation of spatial location.
However, Deouell and colleagues used an improved experimental design that enabled them to more sensitively determine the brain's auditory spatial location center. For example, they presented their human subjects with sounds against a background of silence, used headphones that more accurately reproduced sound location, used noise with a rich spectrum which has been shown to be more readily locatable in space, and created an individually tailored sound space for each subject by using sounds previously recorded directly from the subjects' own ears.
In their experiments, they presented bursts of the noise to the volunteers wearing the headphones while the subjects' brains were scanned by functional magnetic resonance imaging. In this widely used brain-scanning technique, harmless magnetic fields and radio waves are used to image blood flow in brain regions, which reflects brain activity in those locations.
The subjects were instructed to ignore the sounds. And, to divert their attention, they either watched a movie with the sound turned off or were given a simple button-pushing task.
When the position of the noise bursts was varied in space, the researchers found that the planum temporale in the subjects' brain was, indeed, activated. What's more, the greater the number of distinct sound locations subjects heard during test runs, the greater the activity in the planum temporale.
The researchers concluded that their experiments "suggest that neurons in this region represent, in a nonintentional or preattentive fashion, the location of sound sources in the environment." They wrote that "Space representation in this region may provide the neural substrate needed for an orientation response to critical auditory events and for linking auditory information with information acquired through other modalities."
The researchers include Leon Y. Deouell of The Hebrew University of Jerusalem and University of California at Berkeley; Aaron S. Heller of University of California at Berkeley; Rafael Malach of Weizmann Institute of Science in Rehovot; and Mark D'Esposito and Robert T. Knight of University of California at Berkeley.
This work was supported by NINDS Grant NS21135 to R.T.K. and an Israel Science Foundation grant 477-05 to L.Y.D.
Reference: Deouell et al.: "Cerebral Responses to Change in Spatial Location of Unattended Sounds." Publishing in Neuron 55, 985--996, September 20, 2007. DOI 10.1016/j.neuron.2007.08.019.

HIV's Impact In Zimbabwe Explored In New Research

The new research shows that the population of the country continues to grow. However, in the worst affected areas, HIV has reduced the level of population growth by two thirds, from 2.9% to 1.0% each year.
The study is the first to look in detail at the demographic impact of HIV in Zimbabwe. The researchers, from Imperial College London and the Biomedical Research and Training Institute in Harare, focus on an area in the Manicaland region in the east of Zimbabwe over the period 1998 -- 2005.

They show that the crude death rate was double what it would have been in the absence of HIV and the birth rate was somewhat lower. The death rate was approximately three times higher in the towns and estates, and twice as high in the villages, as it would have been without HIV.

Amongst those aged 15-54, approximately one person in every three in towns (32.8%), and one person in every five in the estates (22.2%) and villages (17.3%) had HIV.
Dr Simon Gregson, the lead author of the study from the Department of Infectious Disease Epidemiology at Imperial College London, said: "As in other parts of Africa, HIV has had a devastating effect on the lives of people in Zimbabwe. However, our research shows that, in spite of countless people having lost their lives to the virus, more people are still being born than are dying. The prevalence of HIV has been coming down in the last few years and, as more people receive treatment, we hope the death rate will soon also start to go down."
The research is published the week of August 27 in the journal PNAS.

Note: This story has been adapted from a news release issued by Imperial College London.

Coffee 'protects female memory'

Caffeine may help older women ward off mental decline, research suggests.

French researchers compared women aged 65 and older who drank more than three cups of coffee per day with those who drank one cup or less per day.
Those who drank more caffeine showed less decline in memory tests over a four year period.
The study, published in the journal Neurology, raises the possibility that caffeine may even protect against the development of dementia.

The results held up even after factors such as education, high blood pressure and disease were taken into account.
Caffeine is a known psychostimulant, but this study appears to suggest its effects may be more profound.
However, lead researcher Dr Karen Ritchie of the French National Institute for Health and Medical Research warned against jumping to premature conclusions.
She said: "While we have some ideas as to how this works biologically, we need to have a better understanding of how caffeine affects the brain before we can start promoting caffeine intake as a way to reduce cognitive decline.
"But the results are interesting - caffeine use is already widespread and it has fewer side effects than other treatments for cognitive decline, and it requires a relatively small amount for a beneficial effect."
The study, which involved 7,000 women, did not find that caffeine consumers had lower rates of dementia.
Women 'more sensitive'

Dr Ritchie said: "We really need a longer study to look at whether caffeine prevents dementia; it might be that caffeine could slow the dementia process rather than preventing it."
She said it was not clear why the protective effect did not seem to apply to men.
"Women may be more sensitive to the effects of caffeine. Their bodies may react differently to the stimulant, or they may metabolize caffeine differently."
Rebecca Wood, chief executive of the Alzheimer's Research Trust, said that with no cure for Alzheimer's disease yet available, research into possible protective factors was important, particularly as the disease is expected to become more common.

She said: "This study does not suggest that caffeine actually lowers rates of dementia in women, but since memory seems improved, it may be that it is slowing it down.
"However, research over a much longer period is still needed to establish fully what the affects of caffeine are in both men and women and whether it could reduce a person's risk of dementia or slow down its progress."
Dr Susanne Sorensen, head of research at the Alzheimer's Society, said drinking coffee and tea had both been tipped as possible ways of delaying the onset of dementia.

However, she said: "These types of studies are complex because coffee and tea drinking can be linked to so many other social and life style factors."