Advances Since the 2004 Indian Ocean Tragedy | sci-english.blogspot.com

Tsunami File photo in tamilnadu, india | sci-english.blogspot.com

The Indian Ocean tsunami was one of the worst natural disasters in history. Enormous waves struck countries in South Asia and East Africa with little to no warning, killing 243,000 people. The destruction played out on television screens around the world, fed by shaky home videos. The outpouring of aid in response to the devastation in Indonesia, Sri Lanka, Thailand and elsewhere was unprecedented.

The disaster raised awareness of tsunamis and prompted nations to pump money into research and warning systems.  on the 10th anniversary of the deadly tsunami, greatly expanded networks of seismic monitors and ocean buoys are on alert for the next killer wave in the Indian Ocean, the Pacific and the Caribbean. In fact, tsunami experts can now forecast how tsunamis will flood distant coastlines hours before the waves arrive.

But hurdles remain in saving lives for everyone under the threat of tsunamis. No amount of warning will help those who need to seek immediate shelter away from beaches, disaster experts said.


"A lot of times, you're not going to get any warning near these zones where there are large earthquakes, so we have to prepare the public to interpret the signs and survive," said Mike Angove, head of the National Oceanic and Atmospheric Administration's (NOAA) tsunami program. In 2004, the tsunami waves approached coastal Indonesia just nine minutes after the massive magnitude-9.1 earthquake stopped shaking, Angove said.


 On alert

Since 2004, geologists have uncovered evidence of several massive tsunamis in buried sand layers preserved in Sumatran caves. It turns out that the deadly waves aren't as rare in the Indian Ocean as once thought. "We had five fatal tsunamis off the coast of Sumatra prior to 2004," said Paula Dunbar, a scientist at NOAA's National Geophysical Data Center. Over the past 300 years, 69 tsunamis were seen in the Indian Ocean, she said.

Despite the risk, there was no oceanwide tsunami warning system in the region. Now, a $450 million early-alert network is fully operational, though it is plagued with equipment problems. (Even the global monitoring network loses 10 percent of its buoys each year, according to NOAA.) Essentially built from scratch, the $450 million Indian Ocean Tsunami Warning System (IOWTS) includes more than 140 seismometers, about 100 sea-level gauges and several buoys that detect tsunamis. More buoys were installed, but they have been vandalized or accidentally destroyed. The buoys and gauges help detect whether an earthquake triggered a tsunami.

The global network of Deep-Ocean Assessment and Reporting of Tsunami (DART) buoys, which detects passing tsunami waves, has also expanded, from six buoys in 2004 to 60 buoys in 2014, Angove said.

Regional tsunami alert centers have been built in Australia, India and Indonesia. Scientists at the centers decide whether a tsunami is likely based on information from the network of sensors, estimate the probable size, then alert governments to get the warning out through sirens, TV, radio and text alerts.

Getting the warnings down to people living in remote coastal areas is one of the biggest hurdles for the new system. Not all warnings reach the local level. And not every tsunami earthquake is strong enough to scare people away from shorelines. In Sumatra's Mentawai Islands, a 2010 tsunami killed more than 400 people because residents failed to evacuate in the short time between the earthquake and the tsunami's  arrival. The shaking was simply not strong enough to trigger people's fear of tsunamis, even though islanders had self-evacuated after a 2007 earthquake, according to an investigation by the University of Southern California's Tsunami Research Center. There was also no clear-cut warning from the regional tsunami alert system.

"Tsunami earthquakes remain a major challenge," Emile Okal, a seismologist at Northwestern University in Evanston, Illinois, said Dec. 15 at the American Geophysical Union's (AGU) annual meeting in San Francisco.

Scientists 'map' water vapor in Martian atmosphere | sci-english.blogspot.com

This graphs shows the latitudinal distribution of humidity in Mars' atmosphere during the year according to data collected by the SPICAMInfrared instruments | sci-english.blogspot.com

Russian scientists from the Space Research Institute of the Russian Academy of Sciences and the Moscow Institute of Physics and Technology (MIPT), together with their French and American colleagues, have created a 'map' of the distribution of water vapour in Mars' atmosphere. Their research includes observations of seasonal variations in atmospheric concentrations using data collected over ten years by the Russian-French SPICAM spectrometer aboard the Mars Express orbiter. This is the longest period of observation and provides the largest volume of data about water vapour on Mars.

The first SPICAM (Spectroscopy for Investigation of Characteristics of the Atmosphere of Mars) instrument was built for the Russian Martian orbiter Mars 96, which was lost due to an accident in the rocket launcher.
The new updated version of the instrument was built with the participation of the Space Research Institute as part of the agreement between RosCosmos and the French space agency CNES for the Mars Express orbiter. The apparatus was launched on June 2, 2003 from the Baikonur Cosmodrome using a Russian Soyuz rocket launcher with a Fregat propulsion stage. At the end of December 2003, Mars Express entered a near-Mars orbit and since then has been operating successfully, collecting data on the planet and its surroundings.
Staff of the Space Research Institute and MIPT, including Alexander Trokhimovsky, Anna Fyodorova, Oleg Korablyov and Alexander Rodin, together with their colleagues from the French laboratory LATMOS and NASA's Goddard Center, have analysed a mass of data obtained by observing water vapour in Mars' atmosphere using an infrared spectrometer that is part of the SPICAM instrument over a period of five Martian years (about 10 Earth years as a year on Mars is equal to 1.88 Earth years).
Conditions on Mars -- low temperatures and low atmospheric pressure -- do not allow water to exist in liquid form in open reservoirs as it would on Earth. However, on Mars, there is a powerful layer of permafrost, with large reserves of frozen water concentrated at the polar caps. There is water vapour in the atmosphere, although at very low levels compared to the quantities experienced hereon Earth. If the entire volume of water in the atmosphere was to be spread evenly over the surface of the planet, the thickness of the water layer would not exceed 10-20 microns, while on Earth such a layer would be thousands of times thicker.
Data from the SPICAM experiment has allowed scientists to create a picture of the annual cycle of water vapour concentration variation in the atmosphere. Scientists have been observing the atmosphere during missions to Mars since the end of the 1970s in order to make the picture more precise, as well as traceits variability.
The content of water vapour in the atmosphere reaches a maximum level of 60-70 microns of released water in the northern regions during the summer season. The summer maximum in the southern hemisphere is significantly lower -- about 20 microns. The scientists have also established a significant, by 5-10 microns, reduction in the concentration of water vapour during global sandstorms, which is probably connected to the removal of water vapour from the atmosphere due to adsorption processes and condensation on surfaces.
"This research, based on one of the longest periods of monitoring of the Martian climate, has made an important contribution to the understanding of the Martian hydrological cycle -- the most important of the climate mechanisms which could potentially support the existence of biological activity on the planet," said co-author of the research Alexander Rodin, deputy head of the Infrared Spectroscopy of Planetary Atmospheres Laboratory at MIPT and senior scientific researcher at the Space Research Institute.

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Story Source:
The above story is based on materials provided by Moscow Institute of Physics and Technology. Note: Materials may be edited for content and length.

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Journal Reference:

1. Alexander Trokhimovskiy, Anna Fedorova, Oleg Korablev, Franck Montmessin, Jean-Loup Bertaux, Alexander Rodin, Michael D. Smith. Mars’ water vapor mapping by the SPICAM IR spectrometer: Five martian years of observations. Icarus, 2014; DOI: 10.1016/j.icarus.2014.10.007

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Dust devil and the details: Spinning up a storm on Mars | sci-english.blogspot.com

A dust devil reaching half a mile above the plain of Amazonis Planitia is twisted by the wind at different levels above the surface | sci-english.blogspot.com

Spinning up a dust devil in the thin air of Mars requires a stronger updraft than is needed to create a similar vortex on Earth, according to research at The University of Alabama in Huntsville (UAH).

Early results from this research in UAH's Atmospheric Science Department are scheduled for presentation today at the American Geophysical Union's fall meeting in San Francisco.
"To start a dust devil on Mars you need convection, a strong updraft," said Bryce Williams, an atmospheric science graduate student at UAH. "We looked at the ratio between convection and surface turbulence to find the sweet spot where there is enough updraft to overcome the low level wind and turbulence. And on Mars, where we think the process that creates a vortex is more easily disrupted by frictional dissipation -- turbulence and wind at the surface -- you need twice as much convective updraft as you do on Earth."
Williams and UAH's Dr. Udaysankar Nair looked for the dust devil sweet spot by combining data from a study of Australian dust devils with meteorological observations collected during the Viking Lander mission. They used that data and a one-dimensional Mars planetary boundary layer model to find thresholds of the ratio between convection and surface friction velocities that identify conditions conducive to forming dust devils.
While dust devils on Earth are seldom more than meteorological curiosities, on Mars they sometimes grow to the size of terrestrial tornados, with a funnel more than 100 meters wide stretching as much as 12 miles above the Martian surface.
Williams and Nair are looking at the effects dust devils have on lifting dust into the Martian atmosphere. Dust in the Martian air and its radiative forcing are important modulators of the planet's climate.
"The Martian air is so thin, dust has a greater effect on energy transfers in the atmosphere and on the surface than it does in Earth's thick atmosphere," said Nair, an associate professor of atmospheric science. Dust in the Martian air cools the surface during the day and emits long-wave radiation that warms the surface at night.

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Story Source:
The above story is based on materials provided by University of Alabama Huntsville. Note: Materials may be edited for content and length.

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Why String Theory Still Offers Hope We Can Unify Physics | sci-english.blogspot.com

In October 1984 I arrived at Oxford University, trailing a large steamer trunk containing a couple of changes of clothing and about five dozen textbooks. I had a freshly minted bachelor’s degree in physics from Harvard, and I was raring to launch into graduate study. But within a couple of weeks, the more advanced students had sucked the wind from my sails. Change fields now while you still can, many said. There’s nothing happening in fundamental physics.

Then, just a couple of months later, the prestigious (if tamely titled) journal Physics Letters B published an article that ignited the first superstring revolution, a sweeping movement that inspired thousands of physicists worldwide to drop their research in progress and chase Einstein’s long-sought dream of a unified theory. The field was young, the terrain fertile and the atmosphere electric. The only thing I needed to drop was a neophyte’s inhibition to run with the world’s leading physicists. I did. What followed proved to be the most exciting intellectual odyssey of my life.

That was 30 years ago this month, making the moment ripe for taking stock: Is string theory revealing reality’s deep laws? Or, as some detractors have claimed, is it a mathematical mirage that has sidetracked a generation of physicists?

Unification has become synonymous with Einstein, but the enterprise has been at the heart of modern physics for centuries. Isaac Newton united the heavens and Earth, revealing that the same laws governing the motion of the planets and the Moon described the trajectory of a spinning wheel and a rolling rock. About 200 years later, James Clerk Maxwell took the unification baton for the next leg, showing that electricity and magnetism are two aspects of a single force described by a single mathematical formalism. 

The next two steps, big ones at that, were indeed vintage Einstein. In 1905, Einstein linked space and time, showing that motion through one affects passage through the other, the hallmark of his special theory of relativity. Ten years later, Einstein extended these insights with his general theory of relativity, providing the most refined description of gravity, the force governing the likes of stars and galaxies. With these achievements, Einstein envisioned that a grand synthesis of all of nature’s forces was within reach.

But by 1930, the landscape of physics had thoroughly shifted. Niels Bohr and a generation of intrepid explorers ventured deep into the microrealm, where they encountered quantum mechanics, an enigmatic theory formulated with radically new physical concepts and mathematical rules. While spectacularly successful at predicting the behavior of atoms and subatomic particles, the quantum laws looked askance at Einstein’s formulation of gravity. This set the stage for more than a half-century of despair as physicists valiantly struggled, but repeatedly failed, to meld general relativity and quantum mechanics, the laws of the large and small, into a single all-encompassing description.

Such was the case until December 1984, when John Schwarz, of the California Institute of Technology, and Michael Green, then at Queen Mary College, published a once-in-a-generation paper showing that string theory could overcome the mathematical antagonism between general relativity and quantum mechanics, clearing a path that seemed destined to reach the unified theory. 

The idea underlying string unification is as simple as it is seductive. Since the early 20th century, nature’s fundamental constituents have been modeled as indivisible particles—the most familiar being electrons, quarks and neutrinos—that can be pictured as infinitesimal dots devoid of internal machinery. String theory challenges this by proposing that at the heart of every particle is a tiny, vibrating string-like filament. And, according to the theory, the differences between one particle and another—their masses, electric charges and, more esoterically, their spin and nuclear properties—all arise from differences in how their internal strings vibrate. 

Much as the sonorous tones of a cello arise from the vibrations of the instrument’s strings, the collection of nature’s particles would arise from the vibrations of the tiny filaments described by string theory. The long list of disparate particles that had been revealed over a century of experiments would be recast as harmonious “notes” comprising nature’s score.

Most gratifying, the mathematics revealed that one of these notes had properties precisely matching those of the “graviton,” a hypothetical particle that, according to quantum physics, should carry the force of gravity from one location to another. With this, the worldwide community of theoretical physicists looked up from their calculations. For the first time, gravity and quantum mechanics were playing by the same rules. At least in theory.

I began learning the mathematical underpinnings of string theory during an intense period in the spring and summer of 1985. I wasn’t alone. Graduate students and seasoned faculty alike got swept up in the potential of string theory to be what some were calling the “final theory” or the “theory of everything.” In crowded seminar rooms and flyby corridor conversations, physicists anticipated the crowning of a new order. 

But the simplest and most important question loomed large. Is string theory right? Does the math explain our universe? The description I’ve given suggests an experimental strategy. Examine particles and if you see little vibrating strings, you’re done. It’s a fine idea in principle, but string theory’s pioneers realized it was useless in practice. The math set the size of strings to be about a million billion times smaller than even the minute realms probed by the world’s most powerful accelerators. Save for building a collider the size of the galaxy, strings, if they’re real, would elude brute force detection.

Making the situation seemingly more dire, researchers had come upon a remarkable but puzzling mathematical fact. String theory’s equations require that the universe has extra dimensions beyond the three of everyday experience—left/right, back/forth and up/down. Taking the math to heart, researchers realized that their backs were to the wall. Make sense of extra dimensions—a prediction that’s grossly at odds with what we perceive—or discard the theory.

String theorists pounced on an idea first developed in the early years of the 20th century. Back then, theorists realized that there might be two kinds of spatial dimensions: those that are large and extended, which we directly experience, and others that are tiny and tightly wound, too small for even our most refined equipment to reveal. Much as the spatial extent of an enormous carpet is manifest, but you have to get down on your hands and knees to see the circular loops making up its pile, the universe might have three big dimensions that we all navigate freely, but it might also have additional dimensions so minuscule that they’re beyond our observational reach.

In a paper submitted for publication a day after New Year’s 1985, a quartet of physicists—Philip Candelas, Gary Horowitz, Andrew Strominger and Edward Witten—pushed this proposal one step further, turning vice to virtue. Positing that the extra dimensions were minuscule, they argued, would not only explain why we haven’t seen them, but could also provide the missing bridge to experimental verification.

Strings are so small that when they vibrate they undulate not just in the three large dimensions, but also in the additional tiny ones. And much as the vibrational patterns of air streaming through a French horn are determined by the twists and turns of the instrument, the vibrational patterns of strings would be determined by the shape of the extra dimensions. Since these vibrational patterns determine particle properties like mass, electric charge and so on—properties that can be detected experimentally—the quartet had established that if you know the precise geometry of the extra dimensions, you can make predictions about the results that certain experiments would observe.

For me, deciphering the paper’s equations was one of those rare mathematical forays bordering on spiritual enlightenment. That the geometry of hidden spatial dimensions might be the universe’s Rosetta stone, embodying the secret code of nature’s fundamental constituents—well, it was one of the most beautiful ideas I’d ever encountered. It also played to my strength. As a mathematically oriented physics student, I’d already expended great effort studying topology and differential geometry, the very tools needed to analyze the mathematical form of extra-dimensional spaces.

And so, in the mid-1980s, with a small group of researchers at Oxford, we set our sights on extracting string theory’s predictions. The quartet’s paper had delineated the category of extra-dimensional spaces allowed by the mathematics of string theory and, remarkably, only a handful of candidate shapes were known. We selected one that seemed most promising, and embarked on grueling days and sleepless nights, filled with arduous calculations in higher dimensional geometry and fueled by grandiose thoughts of revealing nature’s deepest workings.

The final results that we found successfully incorporated various established features of particle physics and so were worthy of attention (and, for me, a doctoral dissertation), but were far from providing evidence for string theory. Naturally, our group and many others turned back to the list of allowed shapes to consider other possibilities. But the list was no longer short. Over the months and years, researchers had discovered ever larger collections of shapes that passed mathematical muster, driving the number of candidates into the thousands, millions, billions and then, with insights spearheaded in the mid-1990s by Joe Polchinski, into numbers so large that they’ve never been named. 

Against this embarrassment of riches, string theory offered no directive regarding which shape to pick. And as each shape would affect string vibrations in different ways, each would yield different observable consequences. The dream of extracting unique predictions from string theory rapidly faded.

From a public relations standpoint, string theorists had not prepared for this development. Like the Olympic athlete who promises eight gold medals but wins “only” five, theorists had consistently set the bar as high as it could go. That string theory unites general relativity and quantum mechanics is a profound success. That it does so in a framework with the capacity to embrace the known particles and forces makes the success more than theoretically relevant. Seeking to go even further and uniquely explain the detailed properties of the particles and forces is surely a noble goal, but one that lies well beyond the line dividing success from failure.

Nevertheless, critics who had bristled at string theory’s meteoric rise to dominance used the opportunity to trumpet the theory’s demise, blurring researchers’ honest disappointment of not reaching hallowed ground with an unfounded assertion that the approach had crashed. The cacophony grew louder still with a controversial turn articulated most forcefully by one of the founding fathers of string theory, the Stanford University theoretical physicist Leonard Susskind.

In August 2003, I was sitting with Susskind at a conference in Sigtuna, Sweden, discussing whether he really believed the new perspective he’d been expounding or was just trying to shake things up. “I do like to stir the pot,” he told me in hushed tones, feigning confidence, “but I do think this is what string theory’s been telling us.”

Susskind was arguing that if the mathematics does not identify one particular shape as the right one for the extra dimensions, perhaps there isn’t a single right shape. That is, maybe all of the shapes are right shapes in the sense that there are many universes, each with a different shape for the extra dimensions.

Our universe would then be just one of a vast collection, each with detailed features determined by the shape of their extra dimensions. Why, then, are we in this universe instead of any other? Because the shape of the hidden dimensions yields the spectrum of physical features that allow us to exist. In another universe, for example, the different shape might make the electron a little heavier or the nuclear force a little weaker, shifts that would cause the quantum processes that power stars, including our sun, to halt, interrupting the relentless march toward life on Earth.

Radical though this proposal may be, it was supported by parallel developments in cosmological thinking that suggested that the Big Bang may not have been a unique event, but was instead one of innumerable bangs spawning innumerable expanding universes, called the multiverse. Susskind was suggesting that string theory augments this grand cosmological unfolding by adorning each of the universes in the multiverse with a different shape for the extra dimensions.

With or without string theory, the multiverse is a highly controversial schema, and deservedly so. It not only recasts the landscape of reality, but shifts the scientific goal posts. Questions once deemed profoundly puzzling—why do nature’s numbers, from particle masses to force strengths to the energy suffusing space, have the particular values they do?—would be answered with a shrug. The detailed features we observe would no longer be universal truths; instead, they’d be local bylaws dictated by the particular shape of the extra dimensions in our corner of the multiverse.

Most physicists, string theorists among them, agree that the multiverse is an option of last resort. Yet, the history of science has also convinced us to not dismiss ideas merely because they run counter to expectation. If we had, our most successful theory, quantum mechanics, which describes a reality governed by wholly peculiar waves of probability, would be buried in the trash bin of physics. As Nobel laureate Steven Weinberg has said, the universe doesn’t care about what makes theoretical physicists happy.

This spring, after nearly two years of upgrades, the Large Hadron Collider will crackle back to life, smashing protons together with almost twice the energy achieved in its previous runs. Sifting through the debris with the most complex detectors ever built, researchers will be looking for evidence of anything that doesn’t fit within the battle-tested “Standard Model of particle physics,” whose final prediction, the Higgs boson, was confirmed just before the machine went on hiatus. While it is likely that the revamped machine is still far too weak to see strings themselves, it could provide clues pointing in the direction of string theory. 

Many researchers have pinned their hopes on finding a new class of so-called “supersymmetric” particles that emerge from string theory’s highly ordered mathematical equations. Other collider signals could show hints of extra-spatial dimensions, or even evidence of microscopic black holes, a possibility that arises from string theory’s exotic treatment of gravity on tiny distance scales.

While none of these predictions can properly be called a smoking gun—various non-stringy theories have incorporated them too—a positive identification would be on par with the discovery of the Higgs particle, and would, to put it mildly, set the world of physics on fire. The scales would tilt toward string theory.

But what happens in the event—likely, according to some—that the collider yields no remotely stringy signatures?

Experimental evidence is the final arbiter of right and wrong, but a theory’s value is also assessed by the depth of influence it has on allied fields. By this measure, string theory is off the charts. Decades of analysis filling thousands of articles have had a dramatic impact on a broad swath of research cutting across physics and mathematics. Take black holes, for example. String theory has resolved a vexing puzzle by identifying the microscopic carriers of their internal disorder, a feature discovered in the 1970s by Stephen Hawking. 

Looking back, I’m gratified at how far we’ve come but disappointed that a connection to experiment continues to elude us. While my own research has migrated from highly mathematical forays into extra-dimensional arcana to more applied studies of string theory’s cosmological insights, I now hold only modest hope that the theory will confront data during my lifetime. 

Even so, string theory’s pull remains strong. Its ability to seamlessly meld general relativity and quantum mechanics remains a primary achievement, but the allure goes deeper still. Within its majestic mathematical structure, a diligent researcher would find all of the best ideas physicists have carefully developed over the past few hundred years. It’s hard to believe such depth of insight is accidental.

I like to think that Einstein would look at string theory’s journey and smile, enjoying the theory’s remarkable geometrical features while feeling kinship with fellow travelers on the long and winding road toward unification. All the same, science is powerfully self-correcting. Should decades drift by without experimental support, I imagine that string theory will be absorbed by other areas of science and mathematics, and slowly shed a unique identity. In the interim, vigorous research and a large dose of patience are surely warranted. If experimental confirmation of string theory is in the offing, future generations will look back on our era as transformative, a time when science had the fortitude to nurture a remarkable and challenging theory, resulting in one of the most profound steps toward understanding reality.

Source: http://www.smithsonianmag.com/science-nature/string-theory-about-unravel-180953637/?all

Light-emitting e-readers before bedtime can adversely impact sleep | sci-english.blogspot.com

Use of a light-emitting electronic device (LE-eBook) in the hours before bedtime can adversely impact overall health, alertness, and the circadian clock which synchronizes the daily rhythm of sleep to external environmental time cues | sci-english.blogspot.com

Use of a light-emitting electronic device (LE-eBook) in the hours before bedtime can adversely impact overall health, alertness, and the circadian clock which synchronizes the daily rhythm of sleep to external environmental time cues, according to researchers at Brigham and Women's Hospital (BWH) who compared the biological effects of reading an LE-eBook compared to a printed book. These findings of the study are published in the Proceedings of the National Academy of Sciences on December 22, 2014.

"We found the body's natural circadian rhythms were interrupted by the short-wavelength enriched light, otherwise known as blue light, from these electronic devices," said Anne-Marie Chang, PhD, corresponding author, and associate neuroscientist in BWH's Division of Sleep and Circadian Disorders. "Participants reading an LE-eBook took longer to fall asleep and had reduced evening sleepiness, reduced melatonin secretion, later timing of their circadian clock and reduced next-morning alertness than when reading a printed book."
Previous research has shown that blue light suppresses melatonin, impacts the circadian clock and increase alertness, but little was known about the effects of this popular technology on sleep. The use of light emitting devices immediately before bedtime is a concern because of the extremely powerful effect that light has on the body's natural sleep/wake pattern, and may thereby play a role in perpetuating sleep deficiency.
During the two-week inpatient study, twelve participants read LE-e-Books on an iPad for four hours before bedtime each night for five consecutive nights. This was repeated with printed books. The order was randomized with some reading the iPad first and others reading the printed book first. Participants reading on the iPad took longer to fall asleep, were less sleepy in the evening, and spent less time in REM sleep. The iPad readers had reduced secretion of melatonin, a hormone which normally rises in the evening and plays a role in inducing sleepiness. Additionally, iPad readers had a delayed circadian rhythm, indicated by melatonin levels, of more than an hour. Participants who read from the iPad were less sleepy before bedtime, but sleepier and less alert the following morning after eight hours of sleep. Although iPads were used in this study, BWH researchers also measured other eReaders, laptops, cell phones, LED monitors, and other electronic devices, all emitting blue light.
"In the past 50 years, there has been a decline in average sleep duration and quality," stated Charles Czeisler, PhD, MD, FRCP, chief, BWH Division of Sleep and Circadian Disorders. "Since more people are choosing electronic devices for reading, communication and entertainment, particularly children and adolescents who already experience significant sleep loss, epidemiological research evaluating the long-term consequences of these devices on health and safety is urgently needed."
Researchers emphasize the importance of these findings, given recent evidence linking chronic suppression of melatonin secretion by nocturnal light exposure with the increased risk of breast cancer, colorectal cancer and prostate cancer.

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Story Source:
The above story is based on materials provided by Brigham and Women's Hospital. Note: Materials may be edited for content and length.

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Journal Reference:

1. Anne-Marie Chang, Daniel Aeschbach, Jeanne F. Duffy, and Charles A. Czeisler. Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness. PNAS, December 22, 2014 DOI: 10.1073/pnas.1418490112

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Modern genetics confirm ancient relationship between fins and hands | sci-english.blogspot.com

The same autopod-building genetic switches from gar are able to drive gene activity (purple) in the digits of transgenic mice; an activity that was absent in other fish groups studied | sci-english.blogspot.com

Paleontologists have documented the evolutionary adaptations necessary for ancient lobe-finned fish to transform pectoral fins used underwater into strong, bony structures, such as those of Tiktaalik roseae. This enabled these emerging tetrapods, animals with limbs, to crawl in shallow water or on land. But evolutionary biologists have wondered why the modern structure called the autopod--comprising wrists and fingers or ankles and toes--has no obvious morphological counterpart in the fins of living fishes.

In the Dec. 22, 2014, issue of the Proceedings of the National Academy of Sciences, researchers argue previous efforts to connect fin and fingers fell short because they focused on the wrong fish. Instead, they found the rudimentary genetic machinery for mammalian autopod assembly in a non-model fish, the spotted gar, whose genome was recently sequenced.
"Fossils show that the wrist and digits clearly have an aquatic origin," said Neil Shubin, PhD, the Robert R. Bensley Professor of organismal biology and anatomy at the University of Chicago and a leader of the team that discovered Tiktaalik in 2004. "But fins and limbs have different purposes. They have evolved in different directions since they diverged. We wanted to explore, and better understand, their connections by adding genetic and molecular data to what we already know from the fossil record."
Initial attempts to confirm the link based on shape comparisons of fin and limb bones were unsuccessful. The autopod differs from most fins. The wrist is composed of a series of small nodular bones, followed by longer thin bones that make up the digits. The bones of living fish fins look much different, with a set of longer bones ending in small circular bones called radials.
The primary genes that shape the bones, known as the HoxD and HoxA clusters, also differ. The researchers first tested the ability of genetic "switches" that control HoxD and HoxA genes from teleosts--bony, ray-finned fish--to shape the limbs of developing transgenic mice. The fish control switches, however, did not trigger any activity in the autopod.
Teleost fish--a vast group that includes almost all of the world's important sport and commercial fish--are widely studied. But the researchers began to realize they were not the ideal comparison for studies of how ancient genes were regulated. When they searched for wrist and digit-building genetic switches, they found "a lack of sequence conservation" in teleost species.
They traced the problem to a radical change in the genetics of teleost fish. More than 300 million years ago, after the fish-like creatures that would become tetrapods split off from other bony fish, a common ancestor of the teleost lineage went through a whole-genome duplication (WGD)--a phenomenon that has occurred multiple times in evolution.
By doubling the entire genetic repertoire of teleost fish, this WGD provided them with enormous diversification potential. This may have helped teleosts to adapt, over time, to a variety of environments worldwide. In the process, "the genetic switches that control autopod-building genes were able to drift and shuffle, allowing them to change some of their function, as well as making them harder to identify in comparisons to other animals, such as mice," said Andrew Gehrke, a graduate student in the Shubin lab and lead author of the study.
Not all bony fishes went through the whole genome duplication, however. The spotted gar, a primitive freshwater fish native to North America, split off from teleost fishes before the WGD.
When the research team compared Hox gene switches from the spotted gar with tetrapods, they found "an unprecedented and previously undescribed level of deep conservation of the vertebrate autopod regulatory apparatus." This suggests, they note, a high degree of similarity between "distal radials of bony fish and the autopod of tetrapods."
They tested this by inserting gar gene switches related to fin development into developing mice. This evoked patterns of activity that were "nearly indistinguishable," the authors note, from those driven by the mouse genome.
"Overall," the researchers conclude, "our results provide regulatory support for an ancient origin of the 'late' phase of Hox expression that is responsible for building the autopod."
This study was supported by the Brinson Foundation; the National Science Foundation; the Brazilian National Council for Scientific and Technological Development grants; the National Institutes of Health; the Volkswagen Foundation, Germany; the Alexander von Humboldt-Foundation, the Spanish and Andalusian governments; and Proyecto de Excelencia.
Additional authors include Mayuri Chandran and Tetsuya Nakamura from the University of Chicago; Igor Schneider from the Instituto de Ciencias Biologicas, Universida de Federal do Para, Belem, Brazil; Elisa de la Calle-Mustienes, Juan J. Tena, Carlos Gomez-Marin and José Luis Gómez-Skarmeta from the Centro Andaluz de Biología del Desarrollo, Sevilla, Spain; and Ingo Braasch and John H. Postlethwait from the Institute of Neuroscience, University of Oregon.

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Story Source:
The above story is based on materials provided by University of Chicago Medical Center. Note: Materials may be edited for content and length.

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Journal Reference:

1. Andrew R. Gehrke, Igor Schneider, Elisa de la Calle-Mustienes, Juan J. Tena, Carlos Gomez-Marin, Mayuri Chandran, Tetsuya Nakamura, Ingo Braasch, John H. Postlethwait, José Luis Gómez-Skarmeta, and Neil H. Shubin. Deep conservation of wrist and digit enhancers in fish. PNAS, December 22, 2014 DOI: 10.1073/pnas.1420208112

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Can we test for parallel worlds? | sci-english.blogspot.com

A bold new theory suggests many worlds have existed, side-by-side, since the beginning of time. Cathal O'Connell investigates.


Parallel worlds are standard fare for sci-fi, but the idea originates from quantum physics where the seemingly bizarre notion of alternative universes is taken very seriously. 
Now an Australian team has taken the weirdness a step further. Their new theory, published last month in Physical Review X, is dubbed “Many interacting worlds”. It not only proposes that stable parallel worlds exist but suggests it might be possible to test for their existence.
“It’s kind of a radical idea, but it looks very interesting and promising” says Bill Poirier, a quantum dynamicist at Texas Tech University, who proposed an early version of the theory in 2010.
Parallel worlds were first evoked in the 1950s to explain quantum effects such as how a particle can appear to be in two places at once. Alas Hugh Everett, the American physicist who proposed them, suffered such ridicule he quit science. In his “many worlds” interpretation of quantum theory every quantum measurement causes the universe to “branch” into a bunch of new universes. It was as if, at the flip of a quantum coin, two universes would sprout into existence – one for heads, and one for tails.   
The new theory, bravely proposed by Howard Wiseman, Director of the Centre of Quantum Dynamics at Griffith University, is different. No new universes are ever created. Instead many worlds have existed, side-by-side, since the beginning of time. Some follow the best sci-fi plots, for instance “worlds where the dinosaur-killing asteroid never hit” says Wiseman. Others are almost identical to our own, inhabited by versions of ourselves on alternative Earths, perhaps differing only in the shape of a cirrus cloud above parallel-Melbourne on a bright spring parallel-morning. It’s the interaction of these nearby  worlds that gives rise to quantum effects, the theory says.
So what’s led Wiseman to stir yet another seriously weird theory into the mix?
Physicists have been trying to come to terms with the experimental findings in the quantum world for a century. “It’s still notoriously unfathomable”, he says “This motivated us to look for a better description of what is really going on.”
One of the unfathomable experiments Wiseman is referring to is the “two-slit” experiment for electrons. It’s a version of the famous two-slit experiment first performed by Thomas Young in the 1800s with light. He found that a light beam passing through two closely spaced slits in a screen onto a wall behind did not, as one might expect, produce an image of two lines. Instead it formed an interference pattern rather like the overlapping wakes of two boats, leading Young to deduce that light is a type of wave.
In the early 20th century Niels Bohr and others began to find evidence that fundamental particles, like electrons, also had wave-like properties. The proof came in 1961 when the two-slit experiment was performed with electrons and a wave-like interference pattern, just like that of light, was found.
It was strange to find that particles could act like waves, but then things got stranger. Responding to a suggestion by Richard Feynman, in 1974 Giulio Pozzi and colleagues at the University of Bologna showed you still get an interference pattern when you fire one electron at a time – as if each individual electron passes through both slits and interferes with itself.  Feynman said that all of quantum mechanics could be gleaned from carefully thinking about this one experiment. Physicists have been doing that for decades, yet are still tormented for lack of an intuitive understanding. “The question,” says Wiseman, “is how do you explain what’s going on?”

Einstein abhorred how quantum theory turned the electron from a particle into a cloud. He, like Newton, imagined a universe that ran like clockwork. 

Niels Bohr’s quantum theory managed to predict the behaviours using some strange maths known as the “wave function” to pictures the electron neither as a particle nor a wave, but as a fuzzy “cloud of probability”. But what, exactly, that means in physical terms has never been well defined.  “There has been a lot of debate and controversy for 100 years,” says Poirier.
Einstein abhorred how quantum theory turned the electron from a particle into a cloud. He, like Newton, imagined a universe that ran like clockwork. “God does not play dice,” said Einstein. “I think Einstein should stop telling God what to do,” responded Bohr.
The new theory proposed by the Griffith team is a lot closer to Einstein’s vision than Bohr’s. Gone are the probability clouds along with the other conundrums of wave-particle duality. In the new picture the electrons being fired at the slits are particles after all – tiny little spheres just as Newton would have imagined them. In our world the electron might pass through the bottom slit. But in a parallel world the electron passes through the top slit. As the two ghostly twins travel towards the detectors (one in our world, one in a parallel world), their paths could overlap. But according to the theory, a newly proposed repulsive force stops the electrons coming too close to one another. In effect, the electron in our world “collides” with its ghostly twin, like billiard balls knocking together as they roll across a pool table.
According to Wiseman and his team this interaction between parallel worlds leads to just the type of interference patterns observed – implying electrons are not waves after all. They have supported their theory by running computer simulations of the two-slit experiment using up to 41 interacting worlds. “It certainly captured the essential features of peaks and troughs in the right places,” says Wiseman.
Though he says it is in its early stages, Poirier is impressed with the theory and predicts it will generate huge interest in the physics community. “
By restricting the worlds to be discrete or finite, Poirier adds, the Griffith team has developed equations that are much easier for a computer to solve. Quantum mechanical calculations that would usually take minutes were completed “in a matter of seconds,” says Michael Hall, lead author of the study. Hall hopes that eventually this will lead to applications in predicting real world chemical reactions.
And if the number of worlds is finite – as modelled in the team’s computer simulations – rather than infinite, then the predictions made by the new theory will deviate from standard quantum theory. Though the deviations are likely to be only slight they could be testable in the lab using experiments similar to the double slit. Tantalisingly, as the size of the deviations depends on the number of parallel worlds, these experiments could provide an effective measure of how many worlds are out there.