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Thursday, January 29, 2015

The Two Faces Of Mars: Moon-Sized Celestial Object Crashed Into The South Pole Of Mars

A moon-sized celestial object that crashed into the south pole of Mars: ETH geophysicists have conducted a three-dimensional simulation that shows for the first time how the Red Planet came to have two different hemispheres.

Mars has two differently shaped hemispheres: the lowlands of the northern hemisphere and the volcanic highlands (yellow to red regions) of the southern hemisphere. 
Credits: MOLA Science Team

The two hemispheres of Mars are more different from any other planet in our solar system. Non-volcanic, flat lowlands characterise the northern hemisphere, while highlands punctuated by countless volcanoes extend across the southern hemisphere. Although theories and assumptions about the origin of this so-called and often-discussed Mars dichotomy abound, there are very few definitive answers. ETH Zurich geophysicists with Giovanni Leone are now providing a new explanation. Leone is the lead author of a paper recently published in the journal Geophysical Research Letters.

Using a computer model, the scientists have concluded that a large celestial object must have smashed into the Martian south pole in the early history of the Solar System. Their simulation shows that this impact generated so much energy that it created a magma ocean, which would have extended across what is today’s southern hemisphere. The celestial body that struck Mars must have been at least one-tenth the mass of Mars to be able to unleash enough energy to create this magma ocean. The molten rock eventually solidified into the mountainous highlands that today comprise the southern hemisphere of Mars.

Volcanic activity stopped 3.5 billion years ago

In their simulation, the researchers assumed that the celestial body consisted to a large degree of iron, had a radius of at least 1,600 kilometres, and crashed into Mars at a speed of five kilometres per second. The event is estimated to have occurred around 4 to 15 million years after the Red Planet was formed. Mars’ crust must have been very thin at that time, like the hard, caramelised surface of a crème brûlée. And, just like the popular dessert, hiding beneath the surface was a liquid interior.

When the celestial object impacted, it added more mass to Mars, particularly iron. But the simulation also found that it triggered strong volcanic activity. Around the equator in particular, numerous mantle plumes were generated as a consequence of the impact, which migrated to the south pole where they ended. Mantle plumes are magma columns that transport liquid material from the mantle to the surface.

In the model, the researchers found that activity on Mars died down around 3.5 billion years ago, after which time the Red Planet experienced neither volcanic activity nor a magnetic field – this is consistent with observations and measurements.

3D simulation of an impact of an iron-rich celestial object on the southern pole of Mars.  
Image: from Leone et al. 2014

Earlier theories posited the opposite, namely that there must have been a gigantic impact or many smaller strikes against the northern hemisphere. The most important theory about the origin of the Mars dichotomy was formulated by two American researchers in 1984 in an article in the journalNature. They postulated that a large celestial object struck the Martian north pole. In 2008 a different team revived this idea and published it once again in Nature.

This theory did not convince Leone: “Our scenarios more closely reflect a range of observations about Mars than the theory of a northern hemisphere impact,” states Leone. The volcanoes on Mars are very unevenly distributed: they are common and widespread on the southern hemisphere, but are rare and limited to only a few small regions in the northern hemisphere. "Our model is an almost identical depiction of the actual distribution of volcanic identity,” asserts Leone. According to the researcher, no other model has been able to portray or explain this distribution before.

“Our simulation was also able to reproduce the different topographies of the two hemispheres in an nearly realistic manner,” says Leone. And he goes on to explain that the model – depending on the composition of the impact body chosen – is a virtually perfect representation of the size and shape of the hemispheres. One condition, however, is that the celestial body impacting Mars consist of 80 per cent iron; when the researchers simulated the impact with a celestial body made of pure silicate rock, the resulting image did not correspond to the reality of the dichotomy.

Magnetic field tipped the balance

Lastly, the model developed by the ETH researchers confirmed the date on which the magnetic field on Mars ceased to exist. The date calculated by the model corresponds to around 4.1 billion years ago, a figure previously proven by other scientists. The model also demonstrates why it ceased: a sharp decrease in heat flow from the core into the mantle and the crust in the first 400 million years after the impact. After a billion years, the heat flow was only one-tenth its initial value, which was too low to maintain even the volcanism. The model’s calculations closely match previous calculations and mineralogical explorations.

The volcanic activity is related to the heat flow, explains Leone, though the degree of volcanic activity could be varied in the simulation and influenced by the strength of the impact. This, he states, is in turn linked to the size and composition of the celestial object. In other words, the larger it is, the stronger the volcanic activity is. Nevertheless, after one billion years the volcanic vents were extinguished – regardless of the size of the impact.

It has become increasingly clear to Giovanni Leone that Mars has always been an extremely hostile planet, and he considers it almost impossible that it ever had oceans or even rivers of water. “Before becoming the cold and dry desert of today, this planet was characterised by intense heat and volcanic activity, which would have evaporated any possible water and made the emergence of life highly unlikely,” asserts the planet researcher.


Contacts and sources: 
Peter Rüegg
ETH Zurich


Citation: Leone G, Tackley PJ, Gerya TV, May DA, Zhu G (2014). Three-dimensional simulations of the southern polar giant impact hypothesis for the origin of the Martian dichotomy, Geophys. Res. Lett., 41, doi:10.1002/2014GL062261

Ancient Skull From Galilee Cave Offers Clues To The First Modern Europeans


The discovery of a 55,000-year-old partial skull in Northern Israel provides new insights into the migration of modern humans out of Africa. The rare find is reported in the journal Naturethis week by an international team of Israeli, North American and European researchers.

A key event in human evolution was the expansion of modern humans of African origin across Eurasia, replacing all other forms of hominin (humans and their predecessors), around 40,000-60,000 years ago. However, due to the scarcity of human fossils from this period, these ancestors of all present-day non-African modern populations have largely remained a mystery.

This is the interior of the Manot Cave in Israel's Galilee, where a 55,000-year-old skull sheds new light on modern human migration patterns.

Photo: Amos Frumkin / Hebrew University Cave Research Center)


Now, researchers describe a partial skull that dates to around 55,000, which was found at Manot Cave in Israel's Western Galilee. The Manot Cave was discovered in 2008 during construction activities that damaged its roof. Rock falls and active stalagmites had apparently blocked the initial entrance to the cave for at least 15,000 years. The Hebrew University of Jerusalem's Cave Research Center conducted an initial survey of the cave and reported the findings of archaeological remains.

Prof. Israel Hershkovitz of Tel Aviv University led the anthropological study of the skull, and led the excavation together with archaeologists Dr. Ofer Marder of Ben-Gurion University, and Dr. Omry Barzilai of the Israel Antiquities Authority.

This image shows inside the Manot Cave in Israel's Galilee, where a 55,000-year-old skull sheds new light on modern human migration patterns.

Photo: Amos Frumkin / Hebrew University Cave Research Center

The skull has a distinctive "bun"-shaped occipital region at the back. In this way its shape resembles modern African and European skulls, but differs from other anatomically modern humans from the Levant. This suggests that the Manot people could be closely related to the first modern humans that later colonized Europe.

The specimen also provides evidence that both modern humans and Neanderthals inhabited the southern Levant during the late Pleistocene, close in time to the likely interbreeding event between modern humans and Neanderthals.

Researchers from the Hebrew University played important roles in this discovery. Dating the skull at around 55,000 years is the graduate thesis work of Gal Yasur, a student at the Hebrew University's Earth Sciences Institute in the Faculty of Sciences. The dating work was done at the Geological Survey of Israel under the supervision of GSI Senior Scientists Dr. Miryam Bar-Matthews and Dr. Avner Ayalon, together with Prof. Alan Matthews, the Raymond F. Kravis Professor of Geology at the Hebrew University's Earth Sciences Institute. Prof. Amos Frumkin, Director of the Cave Research Center at the Hebrew University's Geography Department, researched the geological context of the skull in the Manot Cave. Ms. Mae Goder-Goldberger, a doctoral candidate at Hebrew University's Institute of Archaeology, is part of the archaeological team working in the cave.

This finding represents the first fossil evidence from the critical period when genetic and archaeological models predict that African modern humans successfully migrated out of Africa and colonized Eurasia. It also represents the first fossil evidence that during the late Middle Paleolithic, the Levant was occupied not only by Neanderthals but also by modern humans.

The researchers suggest that the population from which this skull is derived had recently migrated out of Africa and established itself in the Levantine corridor during a time span that was favorable for human migration, due to warmer and wetter climatic events over the Northern Sahara and the Mediterranean.




Contacts and sources:
Dov Smith
Hebrew University of Jerusalem

The research appears in the journal Nature under the title "Levantine cranium from Manot Cave (Israel) foreshadows the first European modern humans" (DOI 10.1038/nature14134).

The excavation at Manot Cave was initiated and supported throughout the years by the late Mr. Dan David, founder of the "Dan David Prize", and his son Mr. Ariel David. The ongoing research is financially supported by the Dan David Foundation, the Israel Antiquities Authority (IAA), Case Western Reserve University (CWRU), the Leakey Foundation, the Irene Levi Sala CARE Archaeological Foundation, the Keren Kayemet L'Israel (JNF) and the Israel Science Foundation (ISF). Radiocarbon dating research has been supported by the National Science Foundation (NSF), the Exilarch's Foundation and the MPS-WI Center for Integrative Archaeology and Anthropology.

The Mouth Of The Beast

In 1976 several elongated comet-like objects were discovered on pictures taken with the UK Schmidt Telescope in Australia. Because of their appearance, they became known as cometary globules even though they have nothing in common with comets. They were all located in a huge patch of glowing gas called the Gum Nebula. They had dense, dark, dusty heads and long, faint tails, which were generally pointing away from the Vela supernova remnant located at the centre of the Gum Nebula. Although these objects are relatively close by, it took astronomers a long time to find them as they glow very dimly and are therefore hard to detect.

The object shown in this new picture, CG4, which is also sometimes referred to as God's Hand, is one of these cometary globules. It is located about 1300 light-years from Earth in the constellation of Puppis (The Poop, or Stern).

Like the gaping mouth of a gigantic celestial creature, the cometary globule CG4 glows menacingly in this image from ESO's Very Large Telescope. Although it looks huge and bright in this image it is actually a faint nebula and not easy to observe. The exact nature of CG4 remains a mystery.

Credit:  ESO

The head of CG4, which is the part visible on this image and resembles the head of the gigantic beast, has a diameter of 1.5 light-years. The tail of the globule -- which extends downwards and is not visible in the image -- is about eight light-years long. By astronomical standards this makes it a comparatively small cloud.

The relatively small size is a general feature of cometary globules. All of the cometary globules found so far are isolated, relatively small clouds of neutral gas and dust within the Milky Way, which are surrounded by hot ionised material.

The head part of CG4 is a thick cloud of gas and dust, which is only visible because it is illuminated by the light from nearby stars. The radiation emitted by these stars is gradually destroying the head of the globule and eroding away the tiny particles that scatter the starlight. However, the dusty cloud of CG4 still contains enough gas to make several Sun-sized stars and indeed, CG4 is actively forming new stars, perhaps triggered as radiation from the stars powering the Gum Nebula reached CG4.

The cometary globule CG4 glows menacingly, like the gaping mouth of a gigantic celestial creature, in this pan video based on an image from ESO’s Very Large Telescope. What looks huge and bright in this image is actually a faint nebula and not easy to observe. The exact nature of CG4 remains a mystery.

Credit:  ESO. Music: movetwo

Why CG4 and other cometary globules have their distinct form is still a matter of debate among astronomers and two theories have developed. Cometary globules, and therefore also CG4, could originally have been spherical nebulae, which were disrupted and acquired their new, unusual form because of the effects of a nearby supernova explosion. Other astronomers suggest, that cometary globules are shaped by stellar winds and ionising radiation from hot, massive OB star. These effects could first lead to the bizarrely (but appropriately!) named formations known as elephant trunks and then eventually cometary globules.

To find out more, astronomers need to find out the mass, density, temperature, and velocities of the material in the globules. These can be determined by the measurements of molecular spectral lines which are most easily accessible at millimetre wavelengths -- wavelengths at which telescopes like the Atacama Large Millimeter/submillimeter Array (ALMA) operate.

This picture comes from the ESO Cosmic Gems programme, an outreach initiative to produce images of interesting, intriguing or visually attractive objects using ESO telescopes, for the purposes of education and public outreach. The programme makes use of telescope time that cannot be used for science observations. All data collected may also be suitable for scientific purposes, and are made available to astronomers through ESO's science archive.


Contact and sources:
Richard Hook
ESO

Long-Necked 'Dragon' Discovered In China



University of Alberta paleontologists including PhD student Tetsuto Miyashita, former MSc student Lida Xing and professor Philip Currie have discovered a new species of a long-necked dinosaur from a skeleton found in China. The findings have been published in a new paper in the Journal of Vertebrate Paleontology.

Qijianglong (pronounced "CHI-jyang-lon") is about 15 metres in length and lived about 160 million years ago in the Late Jurassic. The name means "dragon of Qijiang," for its discovery near Qijiang City, close to Chongqing. The fossil site was found by construction workers in 2006, and the digging eventually hit a series of large neck vertebrae stretched out in the ground. Incredibly, the head of the dinosaur was still attached. "It is rare to find a head and neck of a long-necked dinosaur together because the head is so small and easily detached after the animal dies," explains Miyashita.

This illustration shows what the newly discovered long-necked dinosaur may have looked like.

Credit:  Xing Lida

The new species belongs to a group of dinosaurs called mamenchisaurids, known for their extremely long necks sometimes measuring up to half the length of their bodies. Most sauropods, or long-necked dinosaurs, have necks only about one third the length of their bodies.

Unique among mamenchisaurids, Qijianglong had neck vertebrae that were filled with air, making their necks relatively lightweight despite their enormous size. Interlocking joints between the vertebrae also indicate a surprisingly stiff neck that was much more mobile bending vertically than sideways, similar to a construction crane.

"Qijianglong is a cool animal. If you imagine a big animal that is half-neck, you can see that evolution can do quite extraordinary things." says Miyashita.

This shows the reconstructed skeleton of the newly-discovered dinosaur in the gallery of Qijiang Museum, China.


Mamenchisaurids are only found in Asia, but the discovery of Qijianglong reveals that there could be as many differences among mamenchisaurids as there are between long-necked dinosaurs from different continents.

"Qijianglong shows that long-necked dinosaurs diversified in unique ways in Asia during Jurassic times--something very special was going on in that continent," says Miyashita. "Nowhere else we can find dinosaurs with longer necks than those in China. The new dinosaur tells us that these extreme species thrived in isolation from the rest of the world."

Miyashita believes that mamenchisaurids evolved into many different forms when other long-necked dinosaurs went extinct in Asia. "It is still a mystery why mamenchisaurids did not migrate to other continents," he says. It is possible that the dinosaurs were once isolated as a result of a large barrier such as a sea, and lost in competition with invading species when the land connection was restored later.

The Qijianglong skeleton is now housed in a local museum in Qijiang. "China is home to the ancient myths of dragons," says Miyashita, "I wonder if the ancient Chinese stumbled upon a skeleton of a long-necked dinosaur like Qijianglong and pictured that mythical creature."



Contacts and sources:
Tetsuto Miyashita,
Department of Biological Sciences, University of Alberta

Wednesday, January 28, 2015

New Search Engine Lets Users Look For Relevant Results Faster

Researchers at the Helsinki Institute for Information Technology HIIT have developed a new search engine that outperforms current ones, and helps people to do searches more efficiently.

The SciNet search engine is different because it changes internet searches into recognition tasks, by showing keywords related to the user's search in topic radar. People using SciNet can get relevant and diverse search results faster, especially when they do not know exactly what they are looking for or how to formulate a query to find it.

The SciNet search engine changes Internet searches into recognition tasks, by showing keywords related to the user's search in a topic radar.
Credit:  Aalto University

Once initially queried, SciNet displays a range of keywords and topics in a topic radar. With the help of the directions on the radar, the engine displays how these topics are related to each other. The relevance of each keyword is displayed as its distance from the centre point of the radar - those more closely related are nearer to the centre, and those less relevant are farther away. The search engine also offers alternatives that are connected with the topic, but which the user might not have thought of querying. By moving words around the topic radar, users specify what information is most useful for them.

- According to some estimate the digital universe such as data and documents is expected to grow by 2020 by a factor of 10. Tools that help us transform the time we spend in searching into discovering and understanding information will be increasingly important to enhance productivity and creativity. It is exciting to be addressing this problem in research that needs competencies from different disciplines as we uniquely combine at HIIT, states Professor Giulio Jacucci.

When people are uncertain about a topic, they are typically reluctant to reformulate the original query, even if they need to in order to find the right information. With the help of a keyword cloud, people can more quickly infer which of the search options they receive is more significant for them because they do not need to visit the pages offered by the search engine to find new search words and start again.

-It's often hard for people to put what they are looking for into words. Their search needs often do not become more focused until they begin the actual search. The SciNet search engine solves these problems. It's easier for people to recognise what information they want from the options offered by the SciNet search engine than it is to type it themselves, says the project's coordinator, Tuukka Ruotsalo.

The SciNet search engine and the related user modelling were developed at the Helsinki Institute for Information Technology, HIIT, which is a joint research institute of Aalto University and the University of Helsinki in Finland. On the basis of HIIT's research, the company Etsimo Ltd. was founded to commercialize the search engine, which concentrates on supporting complicated searches.

An article on SciNet and its related modeling solutions, "Interactive Intent Modeling: Information Discovery Beyond Search," was recently published in the prominent computing and information technology journal, Communications of the ACM.


Contacts and sources:
Tuukka Ruotsalo
Aalto University

What Are These Yellowballs In Space?


Some four years ago, a citizen scientist helping the Milky Way Project study Spitzer Space Telescope images for the tell-tale bubble patterns of star formation noticed something else.

"Any ideas what these bright yellow fuzzy objects are?" the volunteer wrote on a project message board.

Well, that sparked some discussion among the professional astronomers on the Milky Way Project and eventually led to a study of the compact objects now known as "yellowballs." A paper just published by the Astrophysical Journal ("The Milky Way Project: What are Yellowballs?") answers some questions about the 900 yellowballs tagged by citizen scientists.

Citizen scientists working with the Milky Way Project noticed and tagged the "yellowballs."

Credit: Image courtesy of NASA/JPL-Caltech.

Charles Kerton, an Iowa State University associate professor of physics and astronomy and a member of the Milky Way Project science team, is first author of the paper. Co-authors are Grace Wolf-Chase of the Adler Planetarium in Chicago and the University of Chicago; Kim Arvidsson, formerly an Iowa State doctoral student and now of Schreiner University in Kerrville, Texas; and Chris Lintott and Robert Simpson of the University of Oxford in the United Kingdom.

"In this paper, through a combination of catalog cross-matching and infrared color analysis, we show that yellowballs are a mix of compact star-forming regions," the astronomers wrote.

And, they wrote, the project demonstrates "the serendipitous nature of citizen science efforts" because Milky Way Project volunteers "went beyond their assigned tasks and started tagging and discussing" the yellowballs.

The Milky Way Project is part of the Zooniverse, a collection of Internet-based science projects that ask for the public's help looking through images and other data.

The Milky Way Project asks people to study tens of thousands of Spitzer's infrared images. People are asked to circle and classify various objects, including bubbles of gas and dust blown by the radiation and charged particles from bright young stars.

To date, citizen scientists have made nearly 1.5 million classifications for the project.

Kerton said all of that classifying is helping astronomers study and map star formation within the galaxy.

But the project took a little detour when citizen scientists noticed yellow objects along the rims of some bubble formations. (It should be noted the yellowballs found in Spitzer's infrared images aren't really yellow. When the images are made, various colors are assigned to represent different wavelengths of infrared light. The yellow color on the images highlights where infrared emission from molecules (colored green) and from hot dust (colored red) completely overlap.)

The astronomers began studying those yellowballs by cross-matching them against existing catalogs of space objects. They also studied the luminosity and physical sizes of 138 of the yellowballs.

Kerton said the researchers found most of the yellowballs were located in regions of the galaxy containing dense gas. They also found that yellowball luminosity was consistent with the luminosity expected for a collection of newly formed massive stars.

They've concluded there's an early "yellowball stage" in the formation of stars 10 to 40 times as massive as our sun. The yellowballs are considered very young versions of the bubble formations.

"All massive stars probably go through this yellowball stage," Kerton said. "The most massive stars go through this stage very early and quickly. Less massive stars go through this stage more slowly."

The astronomers also wrote that further studies of yellowballs will improve our understanding of how regions of massive star formation grow from early compact stages to more evolved and bubble-like structures.

But those findings aren't the only highlight of this particular study, Kerton said.

"The fun thing about this study is the involvement of the citizen scientists," he said. "This is a nice example of people looking at something in the universe and saying, 'That's different,' and then passing it on to professional astronomers."


Contacts and sources:
Charles Kerton
Iowa State University

'Astro-Archaeological' Discovery Of Replica Solar System With Earth-Sized Planets From The Dawn Of Time

Scientists led by University of Birmingham asteroseismologists have discovered a solar system with 5 Earth-sized planets dating back to the dawn of the Galaxy.

Thanks to the NASA Kepler mission, the scientists announced today (Tuesday 27 January 2015) in The Astrophysical Journal the observation of a Sun-like star (Kepler-444) hosting 5 planets with sizes between Mercury and Venus.

Illustration showing Kepler-444, which hosts five Earth-sized planets in very compact orbits. The planets were detected from the dimming that occurs when they transit the disc of their parent star, as shown in this artist's conception.
Credit: Tiago Campante/Peter Devine

Kepler-444 was formed 11.2 billion years ago, when the Universe was less than 20% its current age. This is the oldest known system of terrestrial-sized planets in our Galaxy - two and a half times older than the Earth.

The team carried out the research using asteroseismology - listening to the natural resonances of the host star which are caused by sound trapped within it. These oscillations lead to miniscule changes or pulses in its brightness which allow the researchers to measure its diameter, mass and age. The planets were then detected from the dimming that occurs when the planets transited, or passed across, the stellar disc. This fractional fading in the intensity of the light received from the star enables scientists to accurately measure the size of the planets relative to the size of the star.

This animation starts by showing us Kepler's field-of-view in the direction of the constellations Cygnus and Lyra. We are next taken to the vicinity of the Kepler-444 planetary system, located some 117 light years away. Kepler-444, the parent star, was formed 11.2 billion years ago when the Universe was less than 20% its current age. This pale yellow-orange star is 25% smaller than the Sun and substantially cooler.
Credit: Tiago Campante/Peter Devine.

In the animation we see its five planets transiting in front of the stellar disc. Having sizes between those of Mercury and Venus, they cause a tiny dimming of the light received from the star during transit. The last segment of the animation emphasizes the compactness of this system. The five planets orbit their parent star in less than 10 days or, equivalently, at less than one-tenth Earth's distance from the Sun. In a way, this system may be thought of as a miniature version of the inner planets in our own Solar System. 

Dr Tiago Campante, from the University of Birmingham's School of Physics and Astronomy, who led the research, said: 'There are far-reaching implications for this discovery. We now know that Earth-sized planets have formed throughout most of the Universe's 13.8 billion year history, which could provide scope for the existence of ancient life in the Galaxy.

'By the time the Earth formed, the planets in this system were already older than our planet is today. This discovery may now help to pinpoint the beginning of what we might call the "era of planet formation".'

Professor Bill Chaplin, from the University of Birmingham's School of Physics and Astronomy, who has been leading the team studying solar-type stars using asteroseismology for the Kepler Mission, said: 'The first discoveries of exoplanets around other Sun-like stars in our Galaxy have fuelled efforts to find other worlds like Earth and other terrestrial planets outside our Solar System.

'We are now getting first glimpses of the variety of Galactic environments conducive to the formation of these small worlds. As a result, the path towards a more complete understanding of early planet formation in the Galaxy is now unfolding before us.'


Contacts and sources:
Faye Jackson
University of Birmingham

Stomach Acid-Powered Micromotors Get Their First Test In A Living Animal

Researchers at the University of California, San Diego have shown that a micromotor fueled by stomach acid can take a bubble-powered ride inside a mouse. These tiny motors, each about one-fifth the width of a human hair, may someday offer a safer and more efficient way to deliver drugs or diagnose tumors.

The experiment is the first to show that these micromotors can operate safely in a living animal, said Professors Joseph Wang and Liangfang Zhang of the NanoEngineering Department at the UC San Diego Jacobs School of Engineering.



Wang, Zhang and others have experimented with different designs and fuel systems for micromotors that can travel in water, blood and other body fluids in the lab. "But this is the first example of loading and releasing a cargo in vivo," said Wang. "We thought it was the logical extension of the work we have done, to see if these motors might be able to swim in stomach acid."

Stomach acid reacts with the zinc body of the motors to generate a stream of hydrogen microbubbles that propel the motors forward. In their study published in the journal ACS Nano, the researchers report that the motors lodged themselves firmly in the stomach lining of mice. As the zinc motors are dissolved by the acid, they disappear within a few days leaving no toxic chemical traces.

When they loaded up the motors with a test "payload" of gold nanoparticles, Wang, Zhang and their coworkers found that more of these particles reached the stomach lining when carried by the motors, compared to when the particles alone were swallowed. The motors delivered 168 nanograms of gold per gram of stomach tissue, compared to the 53.6 nanograms per gram that was delivered through the traditional oral route.

This video shows the motion of micromotors in gastric acid.

Credit: Jacobs School of Engineering/UC San Diego

"This initial work verifies that this motor can function in a real animal and is safe to use," said Zhang.

In the experiment, the mice ingested tiny drops of solution containing hundreds of the micromotors. The motors become active as soon as they hit the stomach acid and zoom toward the stomach lining at a speed of 60 micrometers per second. They can self-propel like this for up to 10 minutes.

This propulsive burst improved how well the cone-shaped motors were able to penetrate and stick in the mucous layer covering the stomach wall, explained Zhang. "It's the motor that can punch into this viscous layer and stay there, which is an advantage over more passive delivery systems," he said.

The researchers found that nearly four times as many zinc micromotors found their way into the stomach lining compared with platinum-based micromotors, which don't react with and can't be fueled by stomach acid.

Wang said it may be possible to add navigation capabilities and other functions to the motors, to increase their targeting potential. Now that his team has demonstrated that the motors work in living animals, he noted, similar nanomachines soon may find a variety of applications including drug delivery, diagnostics, nanosurgery and biopsies of hard-to-reach tumors.



Contacts and sources:
Ioana Patringenaru
University of California, San Diego

Mesoamericans Affected By Climate Change, A 600 Year Drought

Scientists have reconstructed the past climate for the region around Cantona, a large fortified city in highland Mexico, and found the population drastically declined in the past, at least in part because of climate change.

Cantona was one of the largest cities in pre-Columbian Mesoamerica, with a population of 90,000 inhabitants at its peak. Scientists believe climate change was part of the reason the city was eventually abandoned.
Credit:  Lawrence Livermore

The research appears in the online edition of the Proceedings of the National Academy of Sciences for the week of Jan. 26.

Lawrence Livermore researcher Susan Zimmerman and colleagues analyzed pollen, stable isotopes and elemental concentrations, which serve as proxies of past climatic and environmental conditions from lake sediments in the region and found evidence of a regional drought between 500 and 1150 AD, about the same time Cantona was abandoned.

Using Lawrence Livermore's Center for Accelerator Mass Spectrometry, the team -- consisting of from the University of California, Berkeley; Universidad Nacional Autonóma de Mexico; and the GFZ German Research Center for Geosciences -- dated terrestrial organic material from 12-meter long sediment cores from the lake to establish the age control for this study. Radiocarbon dating and an age model showed that the centennial-scale arid interval between 500 and 1150 was overlaid on a long-term drying trend. The cores cover the last 6,200 years; however, the team focused on the last 3,800 years.

"We found that Cantona's population grew in the initial phases of the drought, but by 1050 AD long-term environmental stress (the drought) contributed to the city's abandonment," Zimmerman and colleagues said. "Our research highlights the interplay of environmental and political factors in past human responses to climate change."

Cantona was one of the largest cities in pre-Columbian Mesoamerica, with a population of 90,000 inhabitants. It is in a semiarid basin east of Mexico City.

The team conducted a subcentennial reconstruction of regional climate by taking sediment samples from a nearby crater lake, Aljojuca. The modern climate of the region suggests that proxy data from the sediments record changes in summer monsoonal (May through October) precipitation.

"Our results suggest that climate change played a contributing role in the site's history," Zimmerman said.


Contacts and sources:
Anne Stark
Lawrence Livermore National Laboratory 

This Common Drug Increases Dementia Risk Including Alzheimer's Disease

A large study links a significantly increased risk for developing dementia, including Alzheimer's disease, to taking commonly used medications with anticholinergic effects at higher doses or for a longer time. Many older people take these medications, which include nonprescription diphenhydramine (Benadryl). JAMA Internal Medicine published the report, called "Cumulative Use of Strong Anticholinergic Medications and Incident Dementia."


 The study used more rigorous methods, longer follow-up (more than seven years), and better assessment of medication use via pharmacy records (including substantial nonprescription use) to confirm this previously reported link. It is the first study to show a dose response: linking more risk for developing dementia to higher use of anticholinergic medications. And it is also the first to suggest that dementia risk linked to anticholinergic medications may persist--and may not be reversible even years after people stop taking these drugs.

"Older adults should be aware that many medications--including some available without a prescription, such as over-the-counter sleep aids--have strong anticholinergic effects," said Shelly Gray, PharmD, MS, the first author of the report, which tracks nearly 3,500 Group Health seniors participating in the long-running Adult Changes in Thought (ACT), a joint Group Health-University of Washington (UW) study funded by the National Institute on Aging. "And they should tell their health care providers about all their over-the-counter use," she added.

Credit: highriskmedications.weebly.com/

"But of course, no one should stop taking any therapy without consulting their health care provider," said Dr. Gray, who is a professor, the vice chair of curriculum and instruction, and director of the geriatric pharmacy program at the UW School of Pharmacy. "Health care providers should regularly review their older patients' drug regimens--including over-the-counter medications--to look for chances to use fewer anticholinergic medications at lower doses."

For instance, the most commonly used medications in the study were tricyclic antidepressants like doxepin (Sinequan), first-generation antihistamines like chlorpheniramine (Chlor-Trimeton), and antimuscarinics for bladder control like oxybutynin (Ditropan). The study estimated that people taking at least 10 mg/day of doxepin, 4 mg/day of chlorpheniramine., or 5 mg/day of oxybutynin for more than three years would be at greater risk for developing dementia. Dr. Gray said substitutes are available for the first two: a selective serotonin re-uptake inhibitor (SSRI) like citalopram (Celexa) or fluoxitene (Prozac) for depression and a second-generation antihistamine like loratadine (Claritin) for allergies. It's harder to find alternative medications for urinary incontinence, but some behavioral changes can reduce this problem.

"If providers need to prescribe a medication with anticholinergic effects because it is the best therapy for their patient," Dr. Gray said, "they should use the lowest effective dose, monitor the therapy regularly to ensure it's working, and stop the therapy if it's ineffective." Anticholinergic effects happen because some medications block the neurotransmitter called acetylcholine in the brain and body, she explained. That can cause many side effects, including drowsiness, sore throat, retaining urine, and dry mouth and eyes.

"With detailed information on thousands of patients for many years, the ACT study is a living laboratory for exploring risk factors for conditions like dementia," said Dr. Gray's coauthor Eric B. Larson, MD, MPH. "This latest study is a prime example of that work and has important implications for people taking medications--and for those prescribing medications for older patients." Dr. Larson is the ACT principal investigator, vice president for research at Group Health, and executive director of Group Health Research Institute (GHRI). He is also a clinical professor of medicine at the UW School of Medicine and of health services at the UW School of Public Health.

Some ACT participants agree to have their brains autopsied after they die. That will make it possible to follow up this research by examining whether participants who took anticholinergic medications have more Alzheimer's-related pathology in their brains compared to nonusers.


Contacts and sources: 
Rebecca Hughes
University of Washington

Easter Island Mystery

Long before the Europeans arrived on Easter Island in 1722, the native Polynesian culture known as Rapa Nui showed signs of demographic decline. However, the catalyst has long been debated in the scientific community. Was environmental degradation the cause, or could a political revolution or an epidemic of disease be to blame?

A new study by a group of international researchers, including UC Santa Barbara's Oliver Chadwick, offers a different explanation and helps to clarify the chronological framework. The investigators expected to find that changes coincided with the arrival of the Europeans, but their work shows instead that the demise of the Rapa Nui culture began prior to that. Their findings are published in the Proceedings of the National Academy of Sciences.

Monolithic human figures called moai were carved from rock between 1250 and 1500 by the inhabitants of Easter Island, which lies more than 2,000 miles off the coast of Chile.
Credit: UC Santa Barbara

"In the current Easter Island debate, one side says the Rapa Nui decimated their environment and killed themselves off," said Chadwick, a professor in UC Santa Barbara's Department of Geography and the Environmental Studies Program. "The other side says it had nothing to do with cultural behavior, that it was the Europeans who brought disease that killed the Rapa Nui. Our results show that there is some of both going on, but the important point is that we show evidence of some communities being abandoned prior to European contact."

Chadwick joined archaeologists Christopher Stevenson of Virginia Commonwealth University, Cedric Puleston of UC Davis and Thegn Ladefoged of the University of Auckland in examining six agriculture sites used by the island's statue-building inhabitants. Their research focused mainly on the three sites for which they had information on climate, soil chemistry and land use trends as determined by an analysis of obsidian spear points.

The team used flakes of obsidian, a natural glass, as a dating tool. Measuring the amount of water that had penetrated the obsidian's surface allowed them to gauge how long it had been exposed and to determine its age.

The study sites reflected the environmental diversity of the 63-square-mile island situated nearly 2,300 miles off the west coast of Chile. The soil nutrient supply on Easter Island is less than that of the younger Hawaiian Islands, which were also settled by the Polynesians around the same time, 1200 A.D.

All fifteen standing moai at Ahu Tongariki, excavated and restored in the 1990s
Credit: Wikipedia

The first site the researchers analyzed was near the northwest coast. Lying in the rain shadow of a volcano, it had low rainfall and relatively high soil nutrient availability. The second study site, on the interior side of the volcanic mountain, experienced high rainfall but had a low nutrient supply; the third, another near-coastal are in the northeast, was characterized by intermediate amounts of rainfall and relatively high soil nutrients.

"When we evaluate the length of time that the land was used based on the age distribution of each site's obsidian flakes, which we used as an index of human habitation, we find that the very dry area and the very wet area were abandoned before European contact," Chadwick said. "The area that had relatively high nutrients and intermediate rainfall maintained a robust population well after European contact."

These results suggest that the Rapa Nui reacted to regional variations and natural environmental barriers to producing sufficient crops rather than degrading the environment themselves. In the nutrient-rich center where they could produce food well, they were able to maintain a viable culture even under the threat of external factors, including European diseases such as smallpox, syphilis and tuberculosis.

"The pullback from the marginal areas suggests that the Rapa Nui couldn't continue to maintain the food resources necessary to keep the statue builders in business," Chadwick concluded. "So we see the story as one of pushing against constraints and having to pull back rather than one of violent collapse."


Contacts and sources:
Julie Cohen
UC Santa Barbara

Bubbles Half The Size Of The Milky Way

Compared to other galaxies, the Milky Way is a peaceful place. But it hasn't always been so sleepy. In 2010, a team of scientists working at the Harvard-Smithsonian Center for Astrophysics discovered a pair of "Fermi bubbles" extending tens of thousands of light-years above and below the Milky Way's disk. 

From end to end, the newly discovered gamma-ray bubbles (magenta) extend 50,000 light-years, or roughly half of the Milky Way's diameter. 
Credit: NASA's Goddard Space Flight Center

These structures are enormous balloons of radiation emanating from the center of our galaxy. They hint at a powerful event that took place millions of years ago, likely when the black hole at the center of our galaxy feasted on an enormous amount of gas and dust - perhaps several hundreds or even thousands of times the mass of the sun.

Fresh from giving the January 6 Rossi Prize lecture at the Winter American Astronomical Society meeting, three physicists who discovered the Fermi bubbles - Douglas Finkbeiner, Tracy Slatyer and Meng Su - spoke with The Kavli Foundation, revealing that studies of the Fermi bubbles may offer insight into the history of our galaxy. With more study, they could also help in the hunt for dark matter.

"It now seems that, in the past, our black hole was tens of millions of times more active than it is currently," said Meng Su, a Pappalardo Fellow and an Einstein Fellow at the Massachusetts Institute of Technology and the MIT Kavli Institute for Astrophysics and Space Research. "Before the discovery of Fermi bubbles, people were discussing that possibility, but there was no single piece of evidence showing that our black hole could be that active. The Fermi bubble discovery changed the picture."

Hints of the Fermi bubbles' edges were first observed in X-rays (blue) by ROSAT, which operated in the 1990s. The gamma rays mapped by the Fermi Gamma-ray Space Telescope (magenta) extend much farther from the galaxy's plane. 
Credit: NASA's Goddard Space Flight Center

Similar bubbles can be seen in other galaxies, but it's still impossible to say whether the Fermi bubbles were produced by the same mechanism as the others, Meng continued. That's because while the Fermi bubbles shine bright in high-energy gamma rays, bubbles in other galaxies are so far away that their gamma rays cannot be seen from Earth. Instead, the distant bubbles are observed in X-rays, radio and microwaves. Future, more precise measurements of the Fermi bubbles in many wavelengths of light may offer insight into how they compare to bubbles in other galaxies, and could help uncover events that took place in our galaxy's core over the past three to four million years.

But that's not all. Further study of the Fermi bubbles, which the astrophysicists first discovered when looking for dark matter, may in fact help identify dark matter. That's because the center of the galaxy, from whence the bubbles originate, is thought to be one of the best places to find evidence of dark matter. Such evidence could be detected as an excess of gamma rays, produced when dark matter particles interact with one another. To find that excess, astrophysicists will need to thoroughly understand the Fermi bubbles. That understanding will allow the researchers to confidently subtract the gamma rays emitted by the Fermi bubbles from the overall gamma-ray signal before looking for an excess of gamma rays coming from dark matter.

Data from the Fermi Telescope shows the bubbles (in red and yellow) against other sources of gamma rays. The plane of the galaxy (mostly black and white) stretches horizontally across the middle of the image, and the bubbles extend up and down from the center. 
Credit: NASA's Goddard Space Flight Center

In some of the most accepted models of dark matter, "we expect the signals from the galactic center to be significantly brighter than anywhere else in the sky," said Tracy Slatyer, an assistant professor of physics at the Massachusetts Institute of Technology and an Affiliated Faculty member at the MIT Kavli Institute for Astrophysics and Space Research. "So just giving up on the galactic center is not generally a good option."

Indeed, Slatyer continued, there are already hints of dark matter appearing in gamma-ray maps of the galactic center - hints that may eventually lead to the discovery of dark matter.

Douglas Finkbeiner, a professor of astronomy and of physics at Harvard University and a member of the Institute for Theory and Computation at the Harvard-Smithsonian Center for Astrophysics, agreed.

"It would be a supreme irony if we found the Fermi bubbles while looking for dark matter and then while studying the Fermi bubbles we discovered dark matter," he said.


Contacts and sources:
Kavli Institute for Astrophysics and Space Research

Tuesday, January 27, 2015

'Kindness Curriculum' Boosts School Success In Preschoolers

Over the course of 12 weeks, twice a week, the prekindergarten students learned their ABCs. Attention, breath and body, caring practice — clearly not the standard letters of the alphabet.

Rather, these 4- and 5-year-olds in the Madison Metropolitan School District were part of a study assessing a new curriculum meant to promote social, emotional and academic skills, conducted by the University of Wisconsin-Madison Center for Investigating Healthy Minds (CIHM) at the Waisman Center.



Researchers found that kids who had participated in the curriculum earned higher marks in academic performance measures and showed greater improvements in areas that predict future success than kids who had not. The results were recently published in the journal Developmental Psychology.

“This work started a number of years ago when we were looking at ways to possibly help children develop skills for school and academic success, as well as in their role as members of a global community,” says study lead author Lisa Flook, a CIHM scientist. “There was a strong interest in looking at cultivating qualities of compassion and kindness."

While mindfulness-based approaches for children have become popular in recent years, few are backed by rigorous scientific evidence. The research team — graduate research assistant Simon Goldberg; outreach specialist Laura Pinger; and CIHM founder Richard Davidson, the UW-Madison William James and Vilas Professor of Psychology and Psychiatry — set out to change that.

The team developed a curriculum to help children between the ages of 4 and 6 years learn how to be more aware of themselves and others through practices that encourage them to bring mindful attention to present moment experience. These practices, the researchers hypothesized, could enhance the children’s self-regulation skills – such as emotional control and the capacity to pay attention — and influence the positive development of traits like impulse control and kindness.

Past studies show the ability to self-regulate in early childhood predicts better results later in life with health, educational attainment and financial stability. Flook says early childhood is an opportune time to equip children with these skills since their brains are rapidly developing. The skills may also help them cope with future life stress.

“Knowing how critical these skills are at an early age, if there are ways to promote them, it could help set kids on a more positive life trajectory,” says Flook.

Throughout the study period, trained CIHM instructors taught the curriculum in diverse classrooms throughout the Madison area and worked with students through hands-on activities involving movement, music and books. Each lesson provided students and teachers the opportunity to participate in mindfulness practices, including activities focused on compassion and gratitude, and to take note of their experience.

For example, kids were encouraged to think about people who are helpful to them – sometimes those they may not know well, like the bus driver — and to reflect on the role these people play in their lives, Flook says.

Teachers reported one of the kids’ favorite activities was a practice called “Belly Buddies,” in which they listened to music while lying on their backs, a small stone resting on their stomachs. They were asked to notice the sensation of the stone, and to feel it rising and falling as they breathed in and out.

“It’s something that’s so simple and it allows them to experience internal quietness and a sense of calm,” says Flook.

They also each received alphabet bracelets to wear, to help them remember their kindness curriculum ABCs.

The curriculum itself is rooted in long-standing adult mindfulness-based practices but was adapted to the children’s developmental ability.

The researchers measured the impact of the curriculum on sharing by using stickers the kids could choose to give to a variety of others or keep for themselves. They measured the kids’ ability to delay gratification by choosing one small reward to have immediately or waiting to receive a larger treat later.

The team looked at how well kids could switch from one mental task to another in a card sorting activity, where they were first asked to sort by shape, then by color, and finally, a mix of both. That’s a particularly challenging skill for young kids, Flook says.

The research team also assessed the students’ ability to pay attention by measuring how well they identified particularly oriented arrows on a screen despite the presence of other on-screen distractions, and it examined the students’ academic performance in the months following the study.

In addition to improved academics, the 30 students who went through the curriculum showed less selfish behavior over time and greater mental flexibility than the 38 kids in the control group.

Flook cautions that while the study was designed as a randomized control trial, additional, larger studies are needed to demonstrate the curriculum’s true power. However, the results demonstrate its potential.

Ultimately, the researchers would like to see mindfulness-based practices become “woven into” the school day, adapted to students across grade levels, becoming a foundation for how teachers teach and how students approach learning, Flook says.

“I think there’s increasing recognition of how social, emotional and cognitive functioning are intermingled; that kids may have difficulty in school when emotional challenges arise and that impacts learning,” she adds. “Can you imagine how this could shift the climate of our schools, our community, our world, if cultivating these qualities was at the forefront of education?”

Credit: Wikipedia

Watch Richard Davidson discuss this project at the 2015 World Economic Forum Annual Meeting in Davos, Switzerland.


Contacts and sources:
 Kelly April Tyrrell
University of Wisconsin-Madison

Nocturnal Leg Cramps More Common In Summer

Painful nocturnal leg cramps are about twice as common during summer than in winter, found a new study in CMAJ (Canadian Medical Association Journal). Nocturnal leg cramps are involuntary muscle contractions that occur in the calves, soles of the feet, or other muscles in the body during the night or (less commonly) while resting.

Credit: Wikipedia

Because quinine is commonly prescribed to treat leg cramps, researchers looked at the number of new quinine prescriptions for adults over 50 years of age in British Columbia, Canada, from Dec. 1, 2001 to Oct. 31, 2007. There were 31 339 people, of whom 61% were female, who began taking quinine during the 6-year study period. The researchers then looked at the frequency of Google searches from the United States and Australia for leg cramps.

They found that prescriptions for quinine peaked in British Columbia in July as did Google searches for leg cramps. In Australia, where mid-summer is in January, Google Trends data indicated a similar peak for leg cramp searches. There was no observed seasonality for search terms for back pain, kidney stones, migraines, acne or panic attacks.

"Although there are anecdotal reports of pregnancy-associated rest cramps being worse in summer, these findings establish the phenomenon of seasonality in rest cramps in the general population," writes Dr. Scott Garrison, Faculty of Medicine, University of Alberta, Edmonton, and the Centre for Hip Health and Mobility, University of British Columbia, Vancouver, with coauthors.

These findings could have implications for clinical practice.

"In countries where quinine is still in widespread use as prophylaxis for nocturnal leg cramps despite safety warnings (e.g., Canada and the United Kingdom), physicians may choose to counsel patients to take a 'quinine holiday' during the 6 colder months of the year," suggest the authors.

In a related commentary http://www.cmaj.ca/site/press/cmaj150044.pdf, Dr. David Hogan, University of Calgary, writes that quinine sulfate, although widely used in Canada to treat nocturnal leg cramps, is not recommended for routine treatment because of safety concerns. Clinicians should first prescribe a 4-week course of quinine to determine if it works and encourage patients to try stopping the drug periodically to minimize use.

"The merit of a 'quinine holiday' during the colder months, as suggested by Garrison and colleagues, becomes moot if patients are not prescribed the agent in the first place or are periodically advised to try stopping it," he writes.



Contacts and sources:
Kim Barnhardt
Canadian Medical Association Journal

Entanglement On A Chip: Breakthrough Promises Secure Communications And Faster Computers


Unlike Bilbo's magic ring, which entangles human hearts, engineers have created a new micro-ring that entangles individual particles of light, an important first step in a whole host of new technologies.

Entanglement - the instantaneous connection between two particles no matter their distance apart - is one of the most intriguing and promising phenomena in all of physics. Properly harnessed, entangled photons could revolutionize computing, communications, and cyber security. Though readily created in the lab and by comparatively large-scale optoelectronic components, a practical source of entangled photons that can fit onto an ordinary computer chip has been elusive.

Drawing of the silicon ring resonator with its access waveguide. The green wave at the input represents the laser pump, the red and blue wavepackets at the output represent the generated photon pairs, and the infinity symbol linking the two outputs indicates the entanglement between the pair of photons.

Credit: Università degli Studi di Pavia

New research, reported today in The Optical Society's (OSA) new high-impact journal Optica, describes how a team of scientists has developed, for the first time, a microscopic component that is small enough to fit onto a standard silicon chip that can generate a continuous supply of entangled photons.

The new design is based on an established silicon technology known as a micro-ring resonator. These resonators are actually loops that are etched onto silicon wafers that can corral and then reemit particles of light. By tailoring the design of this resonator, the researchers created a novel source of entangled photons that is incredibly small and highly efficient, making it an ideal on-chip component.

"The main advantage of our new source is that it is at the same time small, bright, and silicon based," said Daniele Bajoni, a researcher at the Università degli Studi di Pavia in Italy and co-author on the paper. "The diameter of the ring resonator is a mere 20 microns, which is about one-tenth of the width of a human hair. Previous sources were hundreds of times larger than the one we developed."

From Entanglement to Innovation

Scientists and engineers have long recognized the enormous practical potential of entangled photons. This curious manifestation of quantum physics, which Einstein referred to as "spooky action at a distance," has two important implications in real-world technology.

First, if something acts on one of the entangled photons then the other one will respond to that action instantly, even if it is on the opposite side of a computer chip or even the opposite side of the Galaxy. This behavior could be harnessed to increase the power and speed of computations. The second implication is that the two photons can be considered to be, in some sense, a single entity, which would allow for new communication protocols that are immune to spying.

This seemingly impossible behavior is essential, therefore, for the development of certain next-generation technologies, such as computers that are vastly more powerful than even today's most advanced supercomputers, and secure telecommunications.

Creating Entanglement on a Chip

To bring these new technologies to fruition, however, requires a new class of entangled photon emitters: ones that can be readily incorporated into existing silicon chip technologies. Achieving this goal has been very challenging.

To date, entangled photon emitters - which are principally made from specially designed crystals -- could be scaled down to only a few millimeters in size, which is still many orders of magnitude too large for on-chip applications. In addition, these emitters require a great deal of power, which is a valuable commodity in telecommunications and computing.

To overcome these challenges, the researchers explored the potential of ring resonators as a new source for entangled photons. These well-established optoelectronic components can be easily etched onto a silicon wafer in the same manner that other components on semiconductor chips are fashioned. To "pump," or power, the resonator, a laser beam is directed along an optical fiber to the input side of the sample, and then coupled to the resonator where the photons race around the ring. This creates an ideal environment for the photons to mingle and become entangled.

As photons exited the resonator, the researchers were able to observe that a remarkably high percentage of them exhibited the telltale characteristics of entanglement.

"Our device is capable of emitting light with striking quantum mechanical properties never observed in an integrated source," said Bajoni. "The rate at which the entangled photons are generated is unprecedented for a silicon integrated source, and comparable with that available from bulk crystals that must be pumped by very strong lasers."

Applications and Future Technology

The researchers believe their work is particularly relevant because it demonstrates, for the first time, a quintessential quantum effect, entanglement, in a well-established technology.

"In the last few years, silicon integrated devices have been developed to filter and route light, mainly for telecommunication applications," observed Bajoni. "Our micro-ring resonators can be readily used alongside these devices, moving us toward the ability to fully harness entanglement on a chip." As a result, this research could facilitate the adoption of quantum information technologies, particularly quantum cryptography protocols, which would ensure secure communications in ways that classical cryptography protocols cannot.

According to Bajoni and his colleagues, these protocols have already been demonstrated and tested. What has been missing was a cheap, small, and reliable source of entangled photons capable of propagation in fiber networks, a problem that is apparently solved by their innovation.



Contacts and sources:
The Optical Society

Paper: D. Grassani, S. Azzini, M. Liscidini, M. Galli, M. J. Strain, M. Sorel, J. E. Sipe, and D. Bajoni, "A micrometer-scale integrated silicon source of time-energy entangled photons," Optica, 2, 1, 88-94 (2015)  doi: http://dx.doi.org/10.1364/OPTICA.2.000088

Satellite View Of Developing US Nor'easter, Video

National Weather Service forecasters have been tracking a low pressure area that moved from the Midwest into the Atlantic Ocean today, and is expected to become a strong nor'easter that will bring blizzard conditions to the northeastern U.S. The path of the system was captured in a NASA movie of NOAA's GOES-East satellite imagery.

NOAA's GOES-East satellite captured the center of the developing Nor'easter located off North Carolina's Outer Banks on Jan. 26 in the image from 16:30 UTC (12:30 p.m. EST).
Credit: NASA/NOAA Goes Project

An animation of visible and infrared imagery from NOAA's Geostationary Operational Environmental or GOES satellite captured over the period of January 24 through 26 showed the progression of the developing nor'easter.

The satellite animation began on Jan. 24 when clouds associated with a cold front preceding the low, pushed off the U.S. East coast. The front was followed by a low pressure area that moved from the Midwest to the southeast. That low moved over the Carolinas and exited into the Atlantic Ocean on Jan. 26. NOAA's National Weather Service forecast calls for the low to intensify along the Eastern Seaboard and bring blizzard conditions to the northeastern U.S. on Monday night, January 26 and Tuesday, January 27.

This GOES-East animation shows a cold front push off the U.S. East coast followed by a low pressure area from the Midwest moved southeast and exited the Carolinas into the Atlantic Ocean. That low pressure area is forecast to intensify into a Nor'easter.

Image Credit: NASA/NOAA GOES Project

On Monday, January 26, 2015, the National Weather Service noted: A storm system off the East Coast will continue to strengthen as it develops into a major nor'easter on Monday. As the storm moves up the coast, it is expected to bring snowfall of 1-3 feet or more to many parts of the Northeast through Tuesday evening, including New York City and Boston. Strong, gusty winds will combine with the snow to create blizzard conditions along and near the coast.

Winter storm warnings are in effect for the panhandles of West Virginia and Maryland, much of interior New England down to the northern Mid-Atlantic as well as for Nantucket Island, Massachusetts. Winter weather advisories are in effect for portions of the Ohio Valley, Mid-Atlantic and the southern Appalachians as well as a narrow area across interior New England.

To create the video and imagery, NASA/NOAA's GOES Project located at NASA's Goddard Space Flight Center in Greenbelt, Maryland overlays the cloud data from NOAA's GOES-East satellite on a true-color image of land and ocean created by data from the Moderate Resolution Imaging Spectroradiometer, or MODIS, instrument that flies aboard NASA's Aqua and Terra satellites. Together, these data create the entire animation of the storm and show its movement.

GOES satellites provide the kind of continuous monitoring necessary for intensive data analysis. Geostationary describes an orbit in which a satellite is always in the same position with respect to the rotating Earth. This allows GOES to hover continuously over one position on Earth's surface, appearing stationary. As a result, GOES provide a constant vigil for the atmospheric "triggers" for severe weather conditions such as tornadoes, flash floods, hail storms and hurricanes.


Contacts and sources:
Rob Gutro
NASA Goddard Space Center 

 

Huge Ring System Dwarfs Saturn's Rings, From Earth They Would Be Brighter And Larger Than A Full Moon If They Surrounded Saturn

Astronomers at the Leiden Observatory, The Netherlands, and the University of Rochester, USA, have discovered that the ring system that they see eclipse the very young Sun-like star J1407 is of enormous proportions, much larger and heavier than the ring system of Saturn. The ring system - the first of its kind to be found outside our solar system - was discovered in 2012 by a team led by Rochester's Eric Mamajek.

Artist's conception of the extrasolar ring system circling the young giant planet or brown dwarf J1407b is shown. The rings are shown eclipsing the young sun-like star J1407, as they would have appeared in early 2007. The best fit model is consistent with a system of at least 30 rings, and there are gaps where satellites ("exomoons") may have already formed.
Credit: Ron Miller

A new analysis of the data, led by Leiden's Matthew Kenworthy, shows that the ring system consists of over 30 rings, each of them tens of millions of kilometers in diameter. Furthermore, they found gaps in the rings, which indicate that satellites ("exomoons") may have formed. The result has been accepted for publication in the Astrophysical Journal.

"The details that we see in the light curve are incredible. The eclipse lasted for several weeks, but you see rapid changes on time scales of tens of minutes as a result of fine structures in the rings," says Kenworthy. "The star is much too far away to observe the rings directly, but we could make a detailed model based on the rapid brightness variations in the star light passing through the ring system. If we could replace Saturn's rings with the rings around J1407b, they would be easily visible at night and be many times larger than the full moon."

"This planet is much larger than Jupiter or Saturn, and its ring system is roughly 200 times larger than Saturn's rings are today," said co-author Mamajek, professor of physics and astronomy at the University of Rochester. "You could think of it as kind of a super Saturn."

The astronomers analyzed data from the SuperWASP project - a survey that is designed to detect gas giants that move in front of their parent star. In 2012, Mamajek and colleagues at the University of Rochester reported the discovery of the young star J1407 and the unusual eclipses, and proposed that they were caused by a moon-forming disk around a young giant planet or brown dwarf.

In a third, more recent study also led by Kenworthy, adaptive optics and Doppler spectroscopy were used to estimate the mass of the ringed object. Their conclusions based on these and previous papers on the intriguing system J1407 is that the companion is likely to be a giant planet - not yet seen - with a gigantic ring system responsible for the repeated dimming of J1407's light.

The light curve tells astronomers that the diameter of the ring system is nearly 120 million kilometers, more than two hundred times as large as the rings of Saturn. The ring system likely contains roughly an Earth's worth of mass in light-obscuring dust particles.

Mamajek puts into context how much material is contained in these disks and rings. "If you were to grind up the four large Galilean moons of Jupiter into dust and ice and spread out the material over their orbits in a ring around Jupiter, the ring would be so opaque to light that a distant observer that saw the ring pass in front of the sun would see a very deep, multi-day eclipse," Mamajek says. "In the case of J1407, we see the rings blocking as much as 95 percent of the light of this young Sun-like star for days, so there is a lot of material there that could then form satellites."

In the data the astronomers found at least one clean gap in the ring structure, which is more clearly defined in the new model. "One obvious explanation is that a satellite formed and carved out this gap," says Kenworthy. "The mass of the satellite could be between that of Earth and Mars. The satellite would have an orbital period of approximately two years around J1407b."

Astronomers expect that the rings will become thinner in the next several million years and eventually disappear as satellites form from the material in the disks.

"The planetary science community has theorized for decades that planets like Jupiter and Saturn would have had, at an early stage, disks around them that then led to the formation of satellites," Mamajek explains. "However, until we discovered this object in 2012, no-one had seen such a ring system. This is the first snapshot of satellite formation on million-kilometer scales around a substellar object."

Astronomers estimate that the ringed companion J1407b has an orbital period roughly a decade in length. The mass of J1407b has been difficult to constrain, but it is most likely in the range of about 10 to 40 Jupiter masses.

The researchers encourage amateur astronomers to help monitor J1407, which would help detect the next eclipse of the rings, and constrain the period and mass of the ringed companion. Observations of J1407 can be reported to the American Association of Variable Star Observers (AAVSO). In the meantime the astronomers are searching other photometric surveys looking for eclipses by yet undiscovered ring systems.

Kenworthy adds that finding eclipses from more objects like J1407's companion "is the only feasible way we have of observing the early conditions of satellite formation for the near future. J1407's eclipses will allow us to study the physical and chemical properties of satellite-spawning circumplanetary disks."


Contacts and sources:
Leonor Sierra
 University of Rochester

Monday, January 26, 2015

A First Peek Beneath The Surface Of A Comet


In some of the first research findings to be published from the European Space Agency's Rosetta Mission to the comet 67P/Churyumov-Gerasimenko, scientists including astronomer Peter Schloerb of the University of Massachusetts Amherst report early measurements of the comet's subsurface temperature and production of gas from the surface of its nucleus.

Writing this week in Science, an international team with lead author Samuel Gulkis of the Jet Propulsion Laboratory, Pasadena, describes the first millimeter-wave measurements made from June through September 2014, of the comet's nucleus, subsurface temperature and of water vapor and other molecules in the coma of gas and dust that is beginning to form around the comet as it approaches the Sun.

Writing this week in Science, an international team describes the first millimeter-wave measurements made from June through September 2014, of the comet's nucleus and of water vapor and other molecules in the coma of gas and dust that is beginning to form around the comet as it approaches the Sun.

Credit:  European Space Agency

The researchers used NASA's Microwave Instrument on the Rosetta Orbiter (MIRO), launched as a part of the European Space Agency's Rosetta Mission, to study heat transport in the comet's nucleus along with outgassing and development of the coma as interrelated processes. Data from MIRO's millimeter-wave radio receivers help to map temperature and spectral information during the day, night and across seasons as the comet approached the sun.

Schloerb, a planetary scientist who brings special expertise in radio astronomy and remote sensing to the team, says such measurements and monitoring of the interplay between gas emissions and surface temperature over time by MIRO provides key information that allows scientists to better understand the evolution of the gas and dust that comprise the comet's coma.

Observations of the comet at millimeter wavelengths allow astronomers to measure the temperature beneath the surface of the comet's nucleus and properties of the gases in the coma as well.

"An important contribution is that we're sensing not only the subsurface, we're also looking at the important properties of gases inside the coma. Our instrument puts the two together, providing an integrated look at the important physical processes that make the comet work," the UMass Amherst astronomer says.

Schloerb adds, "That's valuable because we can measure temperature within the surface and then see the gases that are produced directly as the nucleus heats up. The surface and subsurface temperatures vary quite a lot as the comet rotates and changes its orientation towards the sun during its orbit. It will be fun to relate this driving force behind the gaseous emissions and then see how the molecules produced behave in response as the comet moves toward the sun."

"In our initial results, not surprisingly, we found important day-night and seasonal variations in the temperature of the nucleus. It is northern summer now, so the northern latitudes are quite warm, while some southern latitudes are un-illuminated at this time and very cold. We're the only instrument that can make measurements of this un-illuminated part of the comet, so our measurements are completely unique in that area."

Schloerb says the team's observations from Comet P67 show a comet spectrum was not consistent with water vapor coming out the same in all directions. Instead, water vapor flowed out mainly from the illuminated side.

"Right away, by looking at the shape of the spectrum, we knew the emissions were very asymmetrical, with most gas being produced on the dayside where comet was being heated up. This is not a new result, we've known this in a general way for 30 years from ground based observations, but it was sure interesting to see it up close where we can look at the detailed behavior."

Another of the important properties of gases inside the coma, besides composition, is their speed as they escape, Schloerb says. MIRO has the ability to measure the outflow speed of the gasses, which is fundamental to the interpretation of observations of the coma and a key parameter needed to check theoretical models.

The UMass Amherst astronomer, who has studied comets for decades and led the worldwide radio observations of Halley's comet as a part of the International Halley Watch in the 1980s, says, "This has been a pretty neat experience. I've never been on a spacecraft project before, but as a planetary scientist I always wanted to do this. After all those years of sitting and looking through a telescope, to see the spectra come in and make the first maps ever of the comet nucleus is really satisfying."

A component of one of the receivers was built at UMass Amherst by Neal Erickson, a world expert on millimeter and submillimeter receivers.


Contacts and sources:
University of Massachusetts Amherst

H.E.S.S. Finds Three Extremely Luminous Gamma-Ray Sources

Wits scientists are part of a multinational team of astronomers working on the High Energy Stereoscopic System (H.E.S.S.) telescopes that have again demonstrated its excellent capabilities in searching for high-energy gamma rays.

In the latest discovery, H.E.S.S. found three extremely luminous gamma-ray sources in the Large Magellanic Cloud (LMC), a satellite dwarf galaxy of the Milky Way. These are objects of different types, namely the most powerful pulsar wind nebula; the most powerful supernova remnant; and a shell of 270 light years in diameter blown by multiple stars, and supernovae – a so-called superbubble.

The Large Magellanic Cloud (LMC) is ablaze with star-forming regions. From the Tarantula Nebula, the brightest stellar nursery in our cosmic neighborhood, to LHA 120-N 11, part of which is featured in this Hubble image, the small and irregular galaxy is scattered with glowing nebulae, the most noticeable sign that new stars are being born.
Image Credit: ESA/NASA/Hubble

The discovery is announced in the latest edition of the scientific journal, Science, in a research paper titled: The exceptionally powerful TeV ƴ-ray emitters in the Large Magellanic Cloud, which will be published on Friday, 23 January 2015.

“This is a very important breakthrough for the team,” says Professor Sergio Colafrancesco, DST/NRF SKA Research Chair in the Wits School of Physics. “It paves the way to study external galaxies with very high-E telescopes such as H.E.S.S and then later with the planned Cherenkov Telescope Array (CTA) in Namibia. It will lead us to re-examine galaxy evolution and answer questions such as how high-E particles can affect the evolution of cosmic structures in the universe, principally galaxies, and the life cycles of matter in galaxies,” he adds.

Very high-energy gamma rays are the best tracers of cosmic accelerators such as supernova remnants and pulsar wind nebulae – end-products of massive stars. There, charged particles are accelerated to extreme velocities. When these particles encounter light or gas in and around the cosmic accelerators, they emit gamma rays. Very high-energy gamma rays can be measured on Earth by observing the Cherenkov light emitted from the particle showers produced by incident gamma
rays high up in the atmosphere using large telescopes with fast cameras.

The Large Magellanic Cloud (LMC) is a dwarf satellite galaxy of our Milky Way, located about 170.000 light years away and showing us its face. New, massive stars are formed at a high rate in the LMC, and it harbors numerous massive stellar clusters. The LMC’s supernova rate relative to its stellar mass is five times that of our Galaxy. The youngest supernova remnant in the local group of galaxies, SN 1987A, is also a member of the LMC. Therefore, the H.E.S.S. scientists dedicated significant observation to searching for very high-energy gamma rays from this cosmic object.

SN 1987A
Credit: NASA

For a total of 210 hours, H.E.S.S. has observed the largest star-forming region within the LMC called Tarantula Nebula. For the first time in a galaxy outside the Milky Way, individual sources of very high-energy gamma rays could be resolved: three extremely energetic objects of different type.

The so-called superbubble 30 Dor C is the largest known X-ray-emitting shell and appears to have been created by several supernovae and strong stellar winds. Superbubbles are broadly discussed as (complementary or alternative to individual supernova remnants) factories where the galactic cosmic rays are produced. The H.E.S.S. results demonstrate that the bubble is a source of, and filled by, highly energetic particles. The superbubble represents a new class of sources in the very high-energy regime.

Superbubble 30 Dor C 
Credit: Chandra X-ray Observatory

Pulsars are highly magnetized, fast rotating neutron stars that emit a wind of ultra-relativistic particles forming a nebula. The most famous one is the Crab Nebula, one of the brightest sources in the high-energy gamma-ray sky. The pulsar PSR J0537−6910 driving the wind nebula N 157B discovered by the H.E.S.S. telescopes in the LMC is in many respects a twin of the very powerful Crab pulsar in our own Galaxy. However, its pulsar wind nebula N 157B outshines the Crab Nebula by an order of magnitude, in very high-energy gamma rays. Reasons are the lower magnetic field in N 157B and the intense starlight from neighboring star-forming regions, which both promote the generation of high-energy gamma rays.

The supernova remnant N 132D, known as a bright object in the radio and infrared bands, appears to be one of the oldest – and strongest – supernova remnants still glowing in very high-energy gamma rays. Between 2500 and 6000 years old – an age where models predict that the supernova explosion front has slowed down and it ought no longer to be efficiently accelerating particles – it still outshines the strongest supernova remnants in our Galaxy. The observations confirm suspicions raised by other H.E.S.S. observations, that supernova remnants can be much more luminous than thought before.

N 132D
Credit: Chandra X-ray Observatory

Observed at the limits of detectability, and partially overlapping with each other, these new sources challenged the H.E.S.S. scientists. The discoveries were only possible due to the development of advanced methods of interpreting the Cherenkov images captured by the telescopes, improving in particular the precision with which gamma-ray directions can be determined.

Indeed, the new H.E.S.S. II 28 m telescope will boost the performance of the H.E.S.S. telescope system, and in the more distant future the planned Cherenkov Telescope Array (CTA) will provide even deeper and higher-resolution gamma-ray images of the LMC – in the plans for science with CTA, the satellite galaxy is already identified as a “Key Science Project” deserving special attention.
The H.E.S.S. telescope is operated by an international collaboration of scientists with a strong involvement by South African universities, in particular Wits University, North West University, and the Universities of the Free State and Johannesburg.

Wits physicists are particularly involved in data analysis techniques, the development of theoretical interpretation tools of both extragalactic and galactic sources, and in the operational shifts at the telescope location in Namibia.


Contacts and sources:
University of the Witwatersrand (Wits)