OpenX

Unseen Is Free

Unseen Is Free
Try It Now

Google Translate

Wednesday, July 29, 2015

Brown Dwarfs Host Powerful Aurora Displays


Brown dwarf stars host powerful aurora displays just like planets, astronomers have discovered.

The so-called failed stars, which are difficult to detect and also remain hard to classify, are too massive to be planets but physicists from the Universities of Sheffield and Oxford have revealed that they host powerful auroras just like Earth.

The international team of researchers made the discovery by observing a brown dwarf 20 light years away using both radio and optical telescopes. Their findings provide further evidence that suggests these stars act more like supersized planets.

Brown dwarf stars host powerful aurora displays just like planets, astronomers have discovered.
Credit:  Chuck Carter and Gregg Hallinan/Caltech.

Dr Stuart Littlefair, from the University of Sheffield's Department of Physics and Astronomy, said: "Brown dwarfs span the gap between stars and planets and these results are yet more evidence that we need to think of brown dwarfs as beefed-up planets, rather than "failed stars".

"We already know that brown dwarfs have cloudy atmospheres - like planets - although the clouds in brown dwarfs are made of minerals that form rocks on Earth now we know brown dwarfs host powerful auroras too."

He added: "Sometimes the best thing about a scientific result is simply the thrill of discovering something exciting and cool. The northern lights on Earth are one of the most spectacular and beautiful things you can see.

"I've always wanted to see them, but have never got the chance. It's particularly ironic that I got to discover an auroral light show which is vastly more powerful and many light years away!"

Auroral displays result when charged particles manage to enter a planet's magnetic field. Once within the magnetosphere, those particles get accelerated along the planet's magnetic field lines to the planet's poles where they collide with gas atoms in the atmosphere, producing the bright emissions associated with auroras.

During the study the international research team, led by Professor Gregg Hallinan from the California Institute of Technology, conducted an extensive observation campaign of a brown dwarf called LSRJ1835+3259.

The team used the most powerful radio telescope in the world, the National Radio Astronomy Observatory's Karl G. Jansky Very Large Array (JVLA) in New Mexico, as well as optical telescopes including Palomar's Hale Telescope and the W.M Keck Observatory's telescopes to make their ground breaking observations.

Using the JVLA they detected a bright pulse of radio waves that appeared as the brown dwarf rotated around. The object rotates every 2.84 hours, so the team were able to watch nearly three full rotations over the course of a single night.

The astronomers worked with the Hale Telescope and observed the brown dwarf varied optically on the same period as the radio pulses. The team found that the object's brightness varied periodically, indicating that there was a bright feature on the brown dwarf's surface. Dr Garret Cotter, from the University of Oxford, who also took part in the study said: "It was incredibly exciting to track the optical light form the aurora during the night with the Hale Telescope in California, one of the most venerable telescopes in the world, while simultaneously tracking the radio emission with the JVLA, one the world's newest radio telescopes."

Finally, the researchers used the Keck telescopes to precisely measure the brightness of the brown dwarf over time which was no simple feat given that these objects are extremely faint, many thousands of times fainter than our own Sun. The astronomers determined that the bright optical feature was likely to be caused by electrons hitting the hydrogen-dominated atmosphere of the brown dwarf to produce auroras.

The findings from the study, published in the journal Nature offer astronomers a convenient stepping stone for further study into exoplanets, planets orbiting stars other than our own sun.

Dr Cotter said: "In science, new knowledge often challenges our understanding. We know how controversial the situation was with Pluto, where astronomers had to look hard to try to decide if it is fundamentally one of the major planets of the solar system, or the first of the Kuiper Belt objects. Now, up at the other end of the size scale, we are challenged by seeing objects that traditionally would have been classified as stars, but seem to be showing more and more properties that make them look like super-sized planets."



Contacts and sources:
Amy Pullan
University of Sheffield

Is Earth’s Magnetic Field Reversing? Clues Found in Anomaly beneath South Africa


A team of researchers has for the first time recovered a magnetic field record from ancient minerals for Iron Age southern Africa (between 1000 and 1500 AD). The data, combined with the current weakening of Earth's magnetic field, suggest that the region of Earth's core beneath southern Africa may play a special role in reversals of the planet's magnetic poles.

Magnetic field strength in the South Atlantic Anomaly is shown. 
Credit:  Graphic by Michael Osadciw/University of Rochester.

The team was led by geophysicist John Tarduno from the University of Rochester and included researchers from Witwatersrand University and Kwa-Zulu Natal University of South Africa.

Reversals of the North and South Poles have occurred irregularly throughout history, with the last one taking place about 800,000 years ago. Once a reversal starts, it can take as long as 15,000 years to complete. The new data suggests the core region beneath southern Africa may be the birthplace of some of the more recent and future pole reversals.

"It has long been thought reversals start at random locations, but our study suggests this may not be the case," said Tarduno, a leading expert on Earth's magnetic field.

The results have been published in the latest issue of the journal Nature Communications.

Tarduno collected the data for his study from five sites along South Africa's borders with Zimbabwe and Botswana, near the Limpopo River. That part of Africa belongs to a region called the South Atlantic Anomaly--extending west beyond South America--that today has an unusually weak magnetic field strength.

Earth's dipole magnetic field strength has decreased 16 percent since 1840--with most of the decay related to the weakening field in the South Atlantic Anomaly--leading to much speculation that the planet is in the early stages of a field reversal. As Tarduno points out, it is only speculation because weakening magnetic fields can recover without leading to a reversal of the poles.

Tarduno and his fellow-researchers believe they found the reason for the unusually low magnetic field strength in that region of the Southern Hemisphere.

"The top of the core beneath this region is overlain by unusually hot and dense mantle rock," said Tarduno.

That hot and dense mantle rock lies 3000 km below the surface, has steep sides, and is about 6000 km across, which is roughly the distance from New York to Paris.

Together with Eric Blackman, an astrophysicist at the University of Rochester, and Michael Watkeys, a geologist at the University of KwaZulu-Natal in South Africa, Tarduno hypothesizes that the region--which is referred to as a Large Low Shear Velocity Province (LLSVP)--affects the direction of the churning liquid iron that generates Earth's magnetic field. Tarduno says it's the shift in the flow of liquid iron that causes irregularities in the magnetic field, ultimately resulting in a loss of magnetic intensity, giving the region its characteristically low magnetic field strength.

Until now, researchers have relied solely on estimates from models derived from data collected at other global sites for an Iron Age record of the magnetic field of southern Africa. Tarduno and his team wanted hard data on both the intensity and direction of the magnetic field, which are recorded and stored in minerals, such as magnetite, at the time they were formed.

The researchers were able to get their data thanks to a knowledge of ancient African practices--in this case, the ritualistic cleansing of villages in agricultural communities. Archeologist Thomas Huffman of Witwatersrand University, a member of the research team and a leading authority on Iron Age southern Africa, explains that villages were cleansed by burning down huts and grain bins. The burning clay floors reached a temperature in excess of 1000 ?C, hot enough to erase the magnetic information stored in the magnetite and create a new record of the magnetic field strength and direction at the time of the burning.

Modern grain bins in southern Africa, which are very similar to the grain bins found in that continent's Iron Age, are pictured.
Photo by John Tarduno/University of Rochester.

Tarduno and his team found a sharp 30 percent drop in magnetic field intensity from 1225 to 1550 AD. Given that the field intensity in the region is also declining today--though less rapidly, as measured by satellites--the research team believes that the process causing the weakening field may be a recurring feature of the magnetic field.

"Because rock in the deep mantle moves less than a centimeter a year, we know the LLSVP is ancient, meaning it may be a longstanding site for the loss of magnetic field strength," said Tarduno. "And it is also possible that the region may actually be a trigger for magnetic pole reversals, which might happen if the weak field region becomes very large."

Earth's dipole magnetic field strength has decreased 16 percent since 1840, leading to much speculation that the planet is in the early stages of a field reversal. Most of the global decay of intensity is related to the weakening field of the Southern Hemisphere that includes Southern Africa.

Tarduno points out that the new data cannot be used to predict with confidence that the present-day magnetic field is entering a reversal. However, it does suggest that the present-day pattern may be the latest manifestation of a repeating feature that occasionally leads to a global field reversal.



Contacts and sources:
Peter Iglinski 
University of Rochester 

What Aluminum Tells Us About Solar System Origins

Physicists at the University of York have revealed a new understanding of nucleosynthesis in stars, providing insight into the role massive stars play in the evolution of the Milky Way and the origins of the Solar System.

The Milky Way arching at a high inclination across the night sky

Credit: Bruno Gilli/ESO

Radioactive aluminium (aluminium-26, or Al26) is an element that emits gamma radiation through its decay enabling astronomers to image its location in our galaxy. Studying how Al26 is created in massive stars, scientists have distinguished between previously conflicting assumptions about its rate of production by nuclear fusion.

Measuring the fusion of helium and sodium at two separate particle accelerators in Canada and Denmark, the rate of production of Al26 was determined to within a factor of two. An improvement on previous experiments where there was disagreement of around a factor of 100 between measurements, this outcome removes dispute about the effect of sodium fusion on the rate of aluminium production.

Al26 is known for its relatively short lifespan (in astrophysical terms), decaying in around 1 million years, compared with the lifetime of massive stars of about 19 million years. This means we are now able to better understand gamma radiation maps of the galaxy, observed by space telescopes such as INTEGRAL and COMPTEL, and deduce a more accurate picture of recent activities of massive stars in the galaxy.

Evidence of Al26 decay observed in meteorites and pre-solar grains also suggests that material from massive stars contaminated the gas cloud from which the Solar System formed, providing insight into its early existence.

Dr Alison Laird, Reader in the University of York’s Department of Physics and lead author on one of the two research papers, said: “This research highlights clear and unambiguous evidence from gamma-ray observations of the galaxy that nucleosynthesis is happening in stars. By pinning down the production rate of radioactive aluminium, we will be able to interpret and understand these observations.

The gas cell target and silicon detector array inside the TUDA scattering chamber at TRIUMF  
Credit: Jessica Tomlinson

“Now we better understand the processes within stars that drive aluminium production, we pave the way for more detailed and thorough research into how massive stars affect our galaxy and the origins of our Solar System.”

Dr Christian Diget, Lecturer in Nuclear Astrophysics in York’s Department of Physics and a lead researcher on the second research paper, said: “These two experiments, completely independent of each other at a technical level and using opposite methodology, provide the most definitive research we have to date of radioactive aluminium production. Through this, we can now much better understand where and how aluminium-26 is produced in stars, and can simulate in the lab how stars work.

“By observing aluminium decay through gamma-radiation maps, we are now able to build a more accurate picture of the conditions when our Solar System formed.”


Contacts and sources:
Saskia Angenent
University of York

Causes of the Viking Age Revealed in New Research

The Viking hit-and-run raids on monastic communities such as Lindisfarne and Iona were the most infamous result of burgeoning Scandinavian maritime prowess in the closing years of the Eighth Century.

The Vale of York Cup - a Christian vessel from northern mainland Europe that was probably held by Scandinavians for some time after its capture, before finishing its life as the receptacle for a large silver hoard buried in Yorkshire. 
Credit : Copyright York Museums Trust (Yorkshire Museum)

These skirmishes led to more expansive military campaigns, settlement, and ultimately conquest of large swathes of the British Isles. But Dr Steve Ashby, of the Department of Archaeology at the University of York, wanted to explore the social justifications for this spike in aggressive activity.

Previous research has considered environmental, demographic, technological and political drivers, as well as the palpable lure of silver and slave and why these forms of wealth became important at this stage.

Dr Ashby said: "I wanted to try to discover what would make a young chieftain invest in the time and resources for such a risky venture. And what were the motives of his crew?"

In research published in Archaeological Dialogues, Dr Ashby argues that focusing on the spoils of raiding is to ignore half the picture as the rewards of such voyages consisted of much more than portable wealth.

Dr Ashby says: "The lure of the exotic, of the world beyond the horizon, was an important factor. Classic anthropology has shown that the mystique of the exotic is a powerful force, and something that leaders and people of influence often use to prop up their power base. It is not difficult to see how this would have worked in the Viking Age."

The acquisition not just of silver but of distinctive forms of Anglo-Saxon, Frankish, and Celtic metalwork were tangible reminders of successful sorties, symbols of status and power, as well as calls-to-arms for future raids. Many of the large quantity of Christian artefacts found in Scandinavian contexts (particularly Norwegian pagan burials) escaped melting and recycling, not because of some form of artistic appreciation, but because they were foundation stones for power, and touchstones in any argument for undertaking military activity.

Dr Ashby says there was also a clear motive for joining raiding parties rather than blindly following their leaders. Raiding activity provided not only an opportunity for violence and the accumulation of wealth, but an arena in which individuals could be noticed by their peers and superiors. It was an opportunity to build reputations for skill, reliability, cunning, or courage. Just as leaders of raiding parties stood to gain more than portable wealth, so too their followers could seek intangible social capital from participation.

"The lure of the raid was thus more than booty; it was about winning and preserving power through the enchantment of travel and the doing of deeds. This provides an important correction to models that focus on the need for portable wealth; the act of acquiring silver was as important as the silver itself," Dr Ashby adds.



Contacts and sources:
David Garner
University of York

Cataclysmic Cosmic Collision Triggered Global Cooling about12,800 Years Ago


At the end of the Pleistocene period, approximately 12,800 years ago­ -- give or take a few centuries -- a cosmic impact triggered an abrupt cooling episode that earth scientists refer to as the Younger Dryas.

New research by UC Santa Barbara geologist James Kennett and an international group of investigators has narrowed the date to a 100-year range, sometime between 12,835 and 12,735 years ago. The team's findings appear today in the Proceedings of the National Academy of Science.

This map shows the Younger Dryas Boundary locations that provided data for the analysis.

Credit: UCSB

The researchers used Bayesian statistical analyses of 354 dates taken from 30 sites on more than four continents. By using Bayesian analysis, the researchers were able to calculate more robust age models through multiple, progressive statistical iterations that consider all related age data.

"This range overlaps with that of a platinum peak recorded in the Greenland ice sheet and of the onset of the Younger Dryas climate episode in six independent key records," explained Kennett, professor emeritus in UCSB's Department of Earth Science. "This suggests a causal connection between the impact event and the Younger Dryas cooling."

In a previous paper, Kennett and colleagues conclusively identified a thin layer called the Younger Dryas Boundary (YDB) that contains a rich assemblage of high-temperature spherules, melt-glass and nanodiamonds, the production of which can be explained only by cosmic impact. However, in order for the major impact theory to be possible, the YDB layer would have to be the same age globally, which is what this latest paper reports.

"We tested this to determine if the dates for the layer in all of these sites are in the same window and statistically whether they come from the same event," Kennett said. "Our analysis shows with 95 percent probability that the dates are consistent with a single cosmic impact event."

This is James Kennett.
Credit: Sonia Fernandez

All together, the locations cover a huge range of distribution, reaching from northern Syria to California and from Venezuela to Canada. Two California sites are on the Channel Islands off Santa Barbara.

However, Kennett and his team didn't rely solely on their own data, which mostly used radiocarbon dating to determine date ranges for each site. They also examined six instances of independently derived age data that used other dating methods, in most cases counting annual layers in ice and lake sediments.

Two core studies taken from the Greenland ice sheet revealed an anomalous platinum layer, a marker for the YDB. A study of tree rings in Germany also showed evidence of the YDB, as did freshwater and marine varves, the annual laminations that occur in bodies of water. Even stalagmites in China displayed signs of abrupt climate change around the time of the Younger Dryas cooling event.

"The important takeaway is that these proxy records suggest a causal connection between the YDB cosmic impact event and the Younger Dryas cooling event," Kennett said. "In other words, the impact event triggered this abrupt cooling.

"The chronology is very important because there's been a long history of trying to figure out what caused this anomalous and enigmatic cooling," he added. "We suggest that this paper goes a long way to answering that question and hope that this study will inspire others to use Bayesian statistical analysis in similar kinds of studies because it's such a powerful tool."


Contacts and sources:
Julie Cohen
UC Santa Barbara

First Finding of Lithium from an Exploding Star Reveals Clues to Evolution of Elements

The chemical element lithium has been found for the first time in material ejected by a nova. Observations of Nova Centauri 2013 made using telescopes at ESO's La Silla Observatory, and near Santiago in Chile, help to explain the mystery of why many young stars seem to have more of this chemical element than expected.

This image from the New Technology Telescope at ESO’s La Silla Observatory shows Nova Centauri 2013 in July 2015 as the brightest star in the centre of the picture. This was more than eighteen months after the initial explosive outburst. This nova was the first in which evidence of lithium has been found.
Credit: ESO

This new finding fills in a long-missing piece in the puzzle representing our galaxy's chemical evolution, and is a big step forward for astronomers trying to understand the amounts of different chemical elements in stars in the Milky Way.

The light chemical element lithium is one of the few elements that is predicted to have been created by the Big Bang, 13.8 billion years ago. But understanding the amounts of lithium observed in stars around us today in the Universe has given astronomers headaches. Older stars have less lithium than expected [1], and some younger ones up to ten times more [2]. 

This chart shows the location of Nova Centauri 2013 (red circle) in the constellation of Centaurus (The Centaur). All the stars easily seen with the naked eye on a dark clear night are shown. The nova erupted in late 2013 and was visible without a telescope. Careful study of the light from this nova has revealed the first traces of the element lithium ever found in a nova.
Credit: ESO/IAU and Sky & Telescope

This video sequence starts from a wide field view of the Milky Way and closes in on the bright and famous pair of stars Alpha and Beta Centauri. Nova Centauri 2013 exploded close to Beta Centauri in the sky in late 2013 and careful study of the light from this star has revealed the first traces of the element lithium ever found in a nova. The final image in the zoom is a closeup of the nova taken using the New Technology Telescope at ESO’s La Silla Observatory in July 2015. The nova is the brightest star close to the centre of the picture and is much fainter than it was at maximum light, when it could be seen with the naked eye.
Credit: ESO/Digitized Sky Survey 2/N. Risinger (skysurvey.org)
Music: Johan B. Monell (www.johanmonell.com).

Since the 1970s, astronomers have speculated that much of the extra lithium found in young stars may have come from novae - stellar explosions that expel material into the space between the stars, where it contributes to the material that builds the next stellar generation. But careful study of several novae has yielded no clear result up to now.

A team led by Luca Izzo (Sapienza University of Rome, and ICRANet, Pescara, Italy) has now used the FEROS instrument on the MPG/ESO 2.2-metre telescope at the La Silla Observatory, as well the PUCHEROS spectrograph on the ESO 0.5-metre telescope at the Observatory of the Pontificia Universidad Catolica de Chile in Santa Martina near Santiago, to study the nova Nova Centauri 2013 (V1369 Centauri). This star exploded in the southern skies close to the bright star Beta Centauri in December 2013 and was the brightest nova so far this century - easily visible to the naked eye [3].

The very detailed new data revealed the clear signature of lithium being expelled at two million kilometres per hour from the nova [4]. This is the first detection of the element ejected from a nova system to date.

Co-author Massimo Della Valle (INAF-Osservatorio Astronomico di Capodimonte, Naples, and ICRANet, Pescara, Italy) explains the significance of this finding: "It is a very important step forward. If we imagine the history of the chemical evolution of the Milky Way as a big jigsaw, then lithium from novae was one of the most important and puzzling missing pieces. In addition, any model of the Big Bang can be questioned until the lithium conundrum is understood."

The mass of ejected lithium in Nova Centauri 2013 is estimated to be tiny (less than a billionth of the mass of the Sun), but, as there have been many billions of novae in the history of the Milky Way, this is enough to explain the observed and unexpectedly large amounts of lithium in our galaxy.

Authors Luca Pasquini (ESO, Garching, Germany) and Massimo Della Valle have been looking for evidence of lithium in novae for more than a quarter of a century. This is the satisfying conclusion to a long search for them. And for the younger lead scientist there is a different kind of thrill:

"It is very exciting," says Luca Izzo, "to find something that was predicted before I was born and then first observed on my birthday in 2013!"

Notes:

[1] The lack of lithium in older stars is a long-standing puzzle. Results on this topic include these press releases: eso1428, eso1235 and eso1132.

[2] More precisely, the terms "younger" and "older" are used to refer to what astronomers call Population I and Population II stars. The Population I category includes the Sun; these stars are rich in heavier chemical elements and form the disc of the Milky Way. Population II stars are older, with a low heavy-element content, and are found in the Milky Way Bulge and Halo, and globular star clusters. Stars in the "younger" Population I class can still be several billion years old!

[3] These comparatively small telescopes, equipped with suitable spectrographs, are powerful tools for this kind of research. Even in the era of extremely large telescopes smaller telescopes dedicated to specific tasks can remain very valuable.

[4] This high velocity, from the nova towards the Earth, means that the wavelength of the line in the absorption in the spectrum due to the presence of lithium is significantly shifted towards the blue end of the spectrum.


Contacts and sources:
Richard Hook
ESO

Dust Pillars of Destruction 1000 Times Larger Than Pillars of Creation, The Last Generation of Stars Will Be Born in Both


Astronomers have long known that powerful cosmic winds can sometimes blow through galaxies, sweeping out interstellar material and stopping future star formation. Now they have a clearer snapshot of how it happens.

This Hubble Space Telescope image of a spiral galaxy in the Coma cluster highlights dust extinction features.

Image courtesy of NASA, ESA, and Roberto Colombari

A Yale University analysis of one such event in a nearby galaxy provides an unprecedented look at the process. The research is described in the Astronomical Journal.

Specifically, Yale astronomer Jeffrey Kenney looked at the way the cosmic wind is eroding the gas and dust at the leading edge of the galaxy. The wind, or ram pressure, is caused by the galaxy's orbital motion through hot gas in the cluster. Kenney found a series of intricate dust formations on the disk's edge, as cosmic wind began to work its way through the galaxy.

"On the leading side of the galaxy, all the gas and dust appears to be piled up in one long ridge, or dust front. But you see remarkable, fine scale structure in the dust front," Kenney explained. "There are head-tail filaments protruding from the dust front. We think these are caused by dense gas clouds becoming separated from lower density gas."
  
The leading side of the disk shows the effects of strong ram pressure. 

Image courtesy of NASA, ESA, and Roberto Colombari

Cosmic wind can easily push low-density clouds of interstellar gas and dust, but not high-density clouds. As the wind blows, denser gas lumps start to separate from the surrounding lower density gas which gets blown downstream. But apparently, the high and low-density lumps are partially bound together, most likely by magnetic fields linking distant clouds of gas and dust.

"The evidence for this is that dust filaments in the HST (Hubble Space Telescope) image look like taffy being stretched out," Kenney said. "We're seeing this decoupling, clearly, for the first time."

The analysis is based on Hubble images of a spiral galaxy in the Coma cluster, located 300 million light years from Earth. It is the closest high-mass cluster to our solar system. Kenney first saw the images two years ago and realized their possible significance in understanding the way ram pressure strips interstellar material throughout the universe.

In the 1990s, a famous Hubble photo dubbed "Pillars of Creation" showed columns of dust and gas in the Eagle Nebula that were in the process of forging new stars. The dust filaments Kenney identified are similar in some ways to the "Pillars of Creation," except they are 1,000 times larger.

Pillars of Creation
 
In both cases, destruction is at least as important as creation. An external force is pushing away most of the gas and dust, therefore destroying most of the cloud, leaving behind only the most dense material -- the pillars. But even the pillars don't last that long.

Because gas is the raw material for star formation, its removal stops the creation of new stars and planets. In the Eagle Nebula, the pressure arises from intense radiation emitted by nearby massive stars; in the Coma galaxy, it is pressure from the galaxy's orbital motion through hot gas in the cluster. Although new stars are being born in both kinds of pillars, we are witnessing, in both, the last generation of stars that will form.

Much of Kenney's research has focused on the physical interplay of galaxies with their environment.

"A great deal of galaxy evolution is driven by interactions," Kenney said. "Galaxies are shaped by collisions and mergers, as well as this sweeping of their gas from cosmic winds. I'm interested in all of these processes."





Contacts and sources:
Jim Shelton
Yale University

Kenney's co-authors on the paper are Yale doctoral student Anne Abramson and Hector-Bravo Alfaro from the Universidad de Guanajuato in Mexico.

Tuesday, July 28, 2015

Immune System ‘On Switch’ Breakthrough Could Lead To New Targeted Drugs

A crucial ‘on switch’ that boosts the body’s defences against infections has been successfully identified in new scientific research.

The breakthrough made by researchers at the University of Aberdeen and the University of Dundee could lead to the development of new drugs to enhance the body’s immune responses to attack, which could benefit people suffering from cancer and other serious conditions.

Credit: University of Dundee

Their findings have been published in the Journal of Molecular and Cell Biology.

“We have shown that the cells which turn on our immune responses to defend against infectious diseases, for example, require a particular protein to activate them in order to function properly,” explained Dr Martin-Granados formerly of the University of Aberdeen and now at Cambridge.

“This protein, or enzyme, (PTP1B) effectively acts as a kind of ‘on switch’ and if it is missing or dysfunctional in our body, we cannot mount effective immune responses to tumours or infections.”

The paper describes the fine tuning of cell signals which orchestrate our immune defences, for instance when we are vaccinated against infections.

Dr Alan Prescott from the University of Dundee added, “The key switch molecule PTP1B allows the uninterrupted production of something called podosomes (which behave like feet for the cell). The cells that turn on our immune systems (dendritic cells) use these “mini-feet” to move though tissue and “home in” on a type of white blood cell called a T cell, which are essential for clearing viruses from our system. These are located at the “glands”, such as those in our neck, which become enlarged when patients get throat infections, for example.”

PTP1B is increased in obesity and diabetics so new drugs that inhibit it are being designed as an anti- diabetic therapy.

Dr Martin-Granados added, “The work shows that this important protein in our cells (PTP1B) is a potential target for new therapies to regulate the immune system when it needs a boost as in severe infections or when it goes wrong as in cancer.”



Contacts and sources:
Roddy Isles
University of Dundee

Volcanic Eruptions Slow Down Climate Change – Temporarily

Volcanic aerosols have acted during the last 10 years as a natural umbrella to slow down global temperature increase from greenhouse gases

The IAGOS-CARIBIC air inlet system mounted at the IAGOS-CARIBIC Airbus.
Credit:  Deutsche Lufthansa AG

Although global concentration of greenhouse gases in the atmosphere has continuously increased over the past decade, the mean global surface temperature has not followed the same path. A team of international reseachers, KIT scientists among them, have now found an explanation for this slowing down in global warming: the incoming solar radiation in the years 2008-2011 was twice as much reflected by volcanic aerosol particles in the lowest part of the stratosphere than previously thought. The team presents their study in Nature Communications

For the lowest part of the stratosphere – i. e. the layer between 10 and 16 kilometres – little information was available so far, but now the international IAGOS-CARIBIC climate project combined with satellite observations from the CALIPSO lidar provided new essential information. According to the study, the cooling effect due to volcanic eruptions was clearly underestimated by climate models used for the last Intergovernmental Panel on Climate Change (IPCC) report. 

Led by the University of Lund, Sweden, and supported by the NASA Langley Research Center, USA, and the Royal Netherlands Meteorological Institute, three major German atmospheric research institutes were also involved: the Max Planck Institute for Chemistry in Mainz (MPI-C), the Leibniz Institute for Tropospheric Research in Leipzig (TROPOS) and the Karlsruhe Institute of Technology (KIT). Since more frequent volcanic eruptions and the subsequent cooling effect are only temporary the rise of Earths’ temperature will speed up again. The reason is the still continuously increasing greenhouse gas concentration, the scientists say.

In the first decade of the 21st century the average surface temperature over the northern mid-latitude continents did increase only slightly. This effect can be now explained by the new study on volcanic aerosol particles in the atmosphere reported here. The study uses data from the tropopause region up to 35 km altitude, where the former is found between 8 km (poles) and 17 km (equator) altitude. The tropopause region is a transition layer between the underlying wet weather layer with its clouds (troposphere) and the dry and cloud-free layer above (stratosphere). 

"Overall our results emphasize that even smaller volcanic eruptions are more important for the Earth´s climate than expected", summarize CARIBIC coordinators Dr. Carl Brenninkmeijer, MPI-C, and Dr. Andreas Zahn, KIT. The IAGOS-CARIBIC observatory was coordinated and operated by the MPI-C until the end of 2014, since then by the KIT.

To collect their data the team combined two different experimental approaches: sampling and in situ measurements made by IAGOS-CARIBIC together with observations from the CALIPSO satellite. In the IAGOS-CARIBIC observatory trace gases and aerosol particles in the tropopause region are measured since 1997. 

A modified air-freight container is loaded once per month for four intercontinental flights into a modified Airbus A340-600 of Lufthansa. Altogether about 100 trace gas and aerosol parameters are measured in situ at 9-12 km altitude as well as in dedicated European research laboratories after flight. TROPOS in Leipzig is responsible for the in situ aerosol particle measurements in this unique project. KIT runs 5 of the 15 installed instruments, also the one for ozone. 

Collected particles are analyzed at the University of Lund, Sweden, using an ion beam accelerator for measuring the amount of particulate sulfur. When comparing this particulate sulfur concentration to the in situ measured ozone concentration this ratio is usually quite constant at cruise altitude. However, volcanic eruptions increase the amount of particulate sulfur and thus the ratio becomes an indicator of volcanic eruption influencing the tropopause region. 

"The ratio of particulate sulfur to ozone from the CARIBIC measurements clearly demonstrates the strong influence from volcanism on the tropopause region”, report Dr. Sandra M. Andersson and Professor Bengt G. Martinsson of the University of Lund, who are the lead authors.

The IAGOS-CARIBIC measurement container in the cargo compartment of the Lufthansa Airbus.
Credit: Stefan Weber, Max-Planck-Institut für Chemie (MPI-C), Mainz

The second method is based on satellite observations. The Cloud-Aerosol Lidar and Pathfinder Satellite Observation (CALIPSO) mission, a collaboration between the National Aeronautics and Space Administration (NASA) in the US and the Centre National d’Etude Spatiale (CNES) in France, has provided unprecedented view on aerosol and cloud layers in the atmosphere. 

Until recently, the data had only been scrutinized above 15 km, namely where volcanic aerosol are known to affect our climate for a long time. Now also aeorosol particles of the lowermost stratosphere have been taken into account for calculating the radiative balance of the atmosphere, to evaluate the impact of smaller volcanic eruptions on the climate.

The CALIPSO satellite 
Credit: NASA

The influence from volcanic eruptions on the stratosphere was small in the northern hemisphere between 1999 and 2002. However, strong signals of volcanic aerosol particles were observed between 2005 and 2012. In particular three eruptions stand out: the Kasatochi in August 2008 (USA), the Sarychev in June 2009 (Russia), and the Nabro in June 2011 (Eritrea). Each of the three eruptions injected more than one megaton sulfur dioxide (SO2) into the atmosphere.  "Virtually all volcanic eruptions reaching the stratosphere lead to more particles there, as they bring in sulfur dioxide, which is converted to sulfate particles," explains Dr. Markus Hermann of TROPOS, who conducts the in situ particle measurements in CARIBIC.

The Sarytschev volcano at an early stage of eruption on June 12, 2009
Credit: NASA
Whether a volcanic eruption has a global climate impact or not depends on several factors. There is the amount of volcanic sulfur dioxide as well as the injection height. But also the latitude of the eruption is important: As the air flow in northern hemispheric stratosphere is largely disconnected from the southern hemisphere, only volcanic eruptions near the equator can effectively distribute the emitted material over both hemispheres. As in the Tambora eruption on the Indonesian Island Sumbawa 200 years ago. This eruption led to such a strong global cooling that the year 1816 was called "year without summer," including worldwide crop failures and famines. 

Also the Krakatau eruption 1883 on Indonesia or the Pinatubo 1991 on the Philippines led to noticeable cooling. The present study now indicates that  "the cooling effect of volcanic eruptions was underestimated in the past, because the lowest part of the stratosphere was mostly not considered. Interestingly our results show that the effect also depends on the season. The eruptions investigated by us had their strongest impact in late summer when the incoming solar radiation is still strong," explains Dr. Sandra M. Andersson.


Contacts and sources:
Monika Landgraf
Karlsruhe Institute of Technology (KIT)

Citation: Sandra M. Andersson, Bengt G. Martinsson, Jean-Paul Vernier, Johan Friberg, Carl A. M. Brenninkmeijer, Markus Hermann, Peter F. J. van Velthoven & Andreas Zahn (2015): Significant radiative impact of volcanic aerosol in the lowermost stratosphere. Nature Communications, doi: 10.1038/ncomms8692.
http://www.nature.com/ncomms/index.html

Face of Copper Age Thankerton Man Reconstructed


The face of a young man dating from the Copper Age, whose skeleton was discovered at Boatbridge Quarry in Thankerton, has been recreated by experts at the University of Dundee.

The face of Thankerton Man is on show to the public at the newly opened Biggar & Upper Clydesdale Museum.

Credit: University of Dundee

His skeleton was found in a stone cist at Boatbridge Quarry, Thankerton in 1970. He was unusually tall, thought to be aged between 18 and 25, and found lying in a crouched position. The remains were radiocarbon dated to between 2460BC and 2140 BC.

The cist contained a finely-decorated Beaker which had held food or drink for the deceased’s journey into the Afterlife. The pot and skeleton are curated by National Museums Scotland.

Working from detailed analysis of the skull, specialists in the Centre for Anatomy and Human Identification (CAHID) at the University of Dundee, one of the world’s leading centres for facial reconstruction, have created a reconstruction of the man’s face.
Credit: University of Dundee

“Given its age, the skeleton of Thankerton Man was in excellent condition, which allowed us to get a strong impression of how he may have looked,” said Caroline Erolin, Lecturer in Forensic and Medical Art at CAHID.

“Once we built the basic shape of his face we then looked at historical data to get a better idea of how a man would have looked at that time. For instance, we know they had the ability to shave.”

The estimated height of the man was around 1.8 metres (5 feet 11 inches), which is regarded as tall in Copper Age terms.

Dr Alison Sheridan, Principal Curator of Early Prehistory at National Museums Scotland, who provided archaeological advice, adds “This is a magnificent piece of work that really brings the past to light. It has spurred us on to arrange the DNA analysis of this man’s remains.”

A new free online course launched by the University of Dundee is set to give the public further insight into the work of CAHID.

`Identifying The Dead: forensic science and human identification’ is a MOOC, or massive open online course, where anyone can sign up to take the six-week course. It has been launched on the FutureLearn platform.


Contacts and sources:
University of Dundee

“Carbon Sink” Detected Underneath World’s Deserts

The world’s deserts may be storing some of the climate-changing carbon dioxide emitted by human activities, a new study suggests. Massive aquifers underneath deserts could hold more carbon than all the plants on land, according to the new research.

Researchers gathered groundwater flowing under the desert sands. The amount of carbon carried by this underground flow increased quickly when the Silk Road, which opened the region to farming, began 2,000 years ago.
Credit: Yan Li

Humans add carbon dioxide to the atmosphere through fossil fuel combustion and deforestation. About 40 percent of this carbon stays in the atmosphere and roughly 30 percent enters the ocean, according to the University Corporation for Atmospheric Research. Scientists thought the remaining carbon was taken up by plants on land, but measurements show plants don’t absorb all of the leftover carbon. Scientists have been searching for a place on land where the additional carbon is being stored—the so-called “missing carbon sink.”

The new study suggests some of this carbon may be disappearing underneath the world’s deserts – a process exacerbated by irrigation. Scientists examining the flow of water through a Chinese desert found that carbon from the atmosphere is being absorbed by crops, released into the soil and transported underground in groundwater—a process that picked up when farming entered the region 2,000 years ago.

Underground aquifers store the dissolved carbon deep below the desert where it can’t escape back to the atmosphere, according to the new study.

The new study estimates that because of agriculture roughly 14 times more carbon than previously thought could be entering these underground desert aquifers every year. These underground pools that taken together cover an area the size of North America may account for at least a portion of the “missing carbon sink” for which scientists have been searching.

“The carbon is stored in these geological structures covered by thick layers of sand, and it may never return to the atmosphere,” said Yan Li, a desert biogeochemist with the Chinese Academy of Sciences in Urumqi, Xinjiang, and lead author of the study accepted for publication in Geophysical Research Letters, a journal of the American Geophysical Union. “It is basically a one-way trip.”

Knowing the locations of carbon sinks could improve models used to predict future climate change and enhance calculations of the Earth’s carbon budget, or the amount of fossil fuels humans can burn without causing major changes in the Earth’s temperature, according to the study’s authors.

Although there are most likely many missing carbon sinks around the world, desert aquifers could be important ones, said Michael Allen, a soil ecologist from the Center for Conservation Biology at the University of California-Riverside who was not an author on the new study.

If farmers and water managers understand the role heavily-irrigated inland deserts play in storing the world’s carbon, they may be able to alter how much carbon enters these underground reserves, he said.

“This means [managers] can take practical steps that could play a role in addressing carbon budgets,” said Allen.

Scientists followed the journey of water through the Tarim Basin from the rivers at the edge of the valley to the desert aquifers under the basin. They found that as water moved through irrigated fields, the water gathered dissolved carbon and moved it deep underground.
Credit: Yan Li

Examining desert water

To find out where deserts tucked away the extra carbon, Li and his colleagues analyzed water samples from the Tarim Basin, a Venezuela-sized valley in China’s Xinjiang region. Water draining from rivers in the surrounding mountains support farms that edge the desert in the center of the basin.

The researchers measured the amount of carbon in each water sample and calculated the age of the carbon to figure out how long the water had been in the ground.

The study shows the amount of carbon dioxide dissolved in the water doubles as it filters through irrigated fields. The scientists suggest carbon dioxide in the air is taken up by the desert crops. Some of this carbon is released into the soil through the plant’s roots. At the same time, microbes also add carbon dioxide to the soil when they break down sugars in the dirt. In a dry desert, this gas would work its way out of the soil into the air. But on arid farms, the carbon dioxide emitted by the roots and microbes is picked up by irrigation water, according to the new study.

In these dry regions, where water is scarce, farmers over-irrigate their land to protect their crops from salts that are left behind when water used for farming evaporates. Over-irrigating washes these salts, along with carbon dioxide that is dissolved in the water, deeper into the earth, according to the new study.

Although this process of carbon burial occurs naturally, the scientists estimate that the amount of carbon disappearing under the Tarim Desert each year is almost 12 times higher because of agriculture. They found that the amount of carbon entering the desert aquifer in the Tarim Desert jumped around the time the Silk Road, which opened the region to farming, begin to flourish.

After the carbon-rich water flows down into the aquifer near the farms and rivers, it moves sideways toward the middle of the desert, a process that takes roughly 10,000 years.

Any carbon dissolved in the water stays underground as it makes its way through the aquifer to the center of the desert, where it remains for thousands of years, according to the new study.

Estimating carbon storage

Based on the various rates that carbon entered the desert throughout history, the study’s authors estimate 20 billion metric tons (22 billion U.S. tons) of carbon is stored underneath the Tarim Basin desert, dissolved in an aquifer that contains roughly 10 times the amount of water held in the North American Great Lakes.

The study’s authors approximate the world’s desert aquifers contain roughly 1 trillion metric tons (1 trillion U.S. tons) of carbon—about a quarter more than the amount stored in living plants on land.

Li said more information about water movement patterns and carbon measurements from other desert basins are needed to improve the estimate of carbon stored underneath deserts around the globe.

Allen said the new study is “an early foray” into this research area. “It is as much a call for further research as a definitive final answer,” he said.



Contacts and sources:
Leigh Cooper
The American Geophysical Union

Citation: “Hidden carbon sink beneath desert” http://onlinelibrary.wiley.com/doi/10.1002/2015GL064222/full?campaign=wlytk-41855.5282060185

Authors:
Y. Li: State Key Lab of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, Xinjiang, China;

Y. Wang: State Key Lab of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, Xinjiang, China;

R.A. Houghton: Woods Hole Research Center, Falmouth, Massachusetts, USA;

L. Tang: State Key Lab of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, Xinjiang, China.

Monday, July 27, 2015

Scientist Discovers Magnetic Material Unnecessary to Create Spin Current

It doesn't happen often that a young scientist makes a significant and unexpected discovery, but postdoctoral researcher Stephen Wu of the U.S. Department of Energy's Argonne National Laboratory just did exactly that. What he found--that you don't need a magnetic material to create spin current from insulators--has important implications for the field of spintronics and the development of high-speed, low-power electronics that use electron spin rather than charge to carry information.

Research at Argonne indicates you don't need a magnetic material to create spin current from insulators -- has important implications for the field of spintronics and the development of high-speed, low-power electronics that use electron spin rather than charge to carry information.
Credit:  Argonne National Laboratory

Wu's work upends prevailing ideas of how to generate a current of spins. "This is a discovery in the true sense," said Anand Bhattacharya, a physicist in Argonne's Materials Science Division and the Center for Nanoscale Materials (a DOE Office of Science user facility), who is the project's principal investigator. "There's no prediction of anything like it."

Spin is a quantum property of electrons that scientists often compare to a tiny bar magnet that points either "up" or "down." Until now scientists and engineers have relied on shrinking electronics to make them faster, but now increasingly clever methods must be used to sustain the continued progression of electronics technology, as we reach the limit of how small we can create a transistor. One such method is to separate the flow of electron spin from the flow of electron current, upending the idea that information needs to be carried on wires and instead flowing it through insulators.

To create a current of spins in insulators, scientists have typically kept electrons stationary in a lattice made of an insulating ferromagnetic material, such as yttrium iron garnet (YIG). When they apply a heat gradient across the material, the spins begin to "move"--that is, information about the orientation of a spin is communicated from one point to another along the lattice, much in the way a wave moves through water without actually transporting the water molecules anywhere. Spin excitations known as magnons are thought to carry the current.

Wu set out to build on previous work with spin currents, expanding it to different materials using a new technique he'd developed. He worked on making devices a thousand times smaller than the typical systems used, giving him more control over the heat and allowing him to create larger thermal gradients in a smaller area. "That was the key to why we were able to do this experiment," he says.

Wu looked at a layer of ferromagnetic YIG on a substrate of paramagnetic gadolinium gallium garnet (GGG). He expected to see no action from the GGG: in a paramagnet the spins aren't aligned as they are in a ferromagnet. They generate no magnetic field, produce no magnons, and there appears to be no way for the spins to communicate with one another. But to everyone's surprise, the spin current was stronger in the GGG than it was in the YIG. "The spins in the system were not talking to each other. But we still found measurable spin current," says Wu. "This effect shouldn't happen at all."

The next step is to figure out why it does.

"We don't know the way this works," said Bhattacharya. "There's an opportunity here for somebody to come up with a theory for this."

The scientists also want to look for other materials that display this effect. "We think that there may be other new physics working here," said Bhattacharya. "Because, since the material is not a ferromagnet, the objects that are moving the spin are not what we typically understand."

In the meantime, said Wu, "We've just taken ferromagnetism off its pedestal. In a spintronic device you don't have to use a ferromagnet. You can use either a paramagnetic metal or a paramagnetic insulator to do it now."



Contacts and sources:
Angela Hardin
Argonne National Laboratory

Citation: "Paramagnetic spin Seebeck effect," published in the journal Physical Review Letters.

What Cosmic Rays Tell Us about Thunderstorms on Earth

When Prof. Heino Falcke obtained an European Research Council (ERC)  grant to study and identify the sources of ultra-high energy cosmic rays, back in 2008, he could not imagine that his research would provide an important clue to better understand lightning and thunderclouds much closer to us. 

Credit: © danmir12 - Fotolia.com

His team indeed realized that cosmic rays, originating in outer space and striking the Earth from all directions, can provide a near instantaneous 'picture' of the electric fields in clouds. The unexpected finding, to be published this week in Physical Review Letters, is the result of a fruitful collaboration between astronomers, particle physicists and geophysicists. The measurements were performed with the LOFAR radio telescope, located in the Netherlands, and partly funded by the ERC.

Cosmic rays are high-energy charged particles. High in the atmosphere, when they strike the atmospheric molecules they create a 'shower' of elementary particles that can reach the Earth's surface. These showers can be measured from the radio emission that is generated when their constituent particles are deflected by the magnetic field of the Earth. The radio emission also gives information about the nature and origin of the particles, and that is exactly what Prof. Falcke focused on between 2009 and 2013 in his ERC funded project "From Black Holes to Ultra-High Energy Cosmic Rays: Exploring the Extremes of the Universe with Low-Frequency Radio Interferometry" (LOFAR AUGER).

Modelling

"We actually used to put aside LOFAR measurements taken during thunderstorms. They were too messy", says astronomer Pim Schellart, who completed his PhD this year and is supervised by Prof. Heino Falcke. That changed when the same data was examined in the context of a collaboration with astrophysicist Gia Trinh, Prof. Olaf Scholten, from Groningen University and lightning expert Ute Ebert, from the Centrum Wiskunde & Informatica in Amsterdam.

"We modelled how the electric field in thunderstorms can explain the different measurements. This worked very well. The variations of the radio emission gave us a lot of information about the electric fields in thunderstorms. We could even determine the strength of the electric field at a certain height in the cloud. This field can be as strong as 50 kV/m and it can translate into a voltage of hundreds of millions of volts over a distance of multiple kilometres: a thundercloud contains enormous amounts of energy," says Dr Schellart.

Dangerous charge

Lightning is a highly unpredictable natural phenomenon that inflicts damage to infrastructure and claims victims around the world. This new method to measure electric fields in thunderclouds will contribute to a better understanding and ultimately better predictions of lightning activity.

Current measurement methods from planes, balloons or little rockets are dangerous and too localized. Most importantly the presence of the measurement equipment influences the measurements. Cosmic rays probe the thunderclouds from top to bottom. Moving at almost the speed of light they provide a near instantaneous 'picture' of the electric fields in the cloud. Moreover, they are created by nature and are freely available.

Building on LOFAR AUGER advances

“The ERC grant has contributed to bring LOFAR to a fully functioning radio telescope that is currently surveying the sky,” says Prof. Falcke. During the course of the project, the team also developed a method to decode the radio signal emitted by cosmic rays in the Earth atmosphere. While their origin has not been solved yet, the team has made a significant step forward in understanding the nature of cosmic rays and how to measure them.

“This method allowed us to collect and give meaning to the data that we are presenting in this publication. This is an exemplary form of interdisciplinary collaboration between astronomers, particle physicists and geophysicists”, says Prof. Falcke. “We now hope to develop the model further to ultimately answer the question: how is lightning initiated within thunderclouds?”



Contacts and sources: 
Prof. Heino Falcke
European Research Council
Written in collaboration with Radboud University.

Citation: Probing atmospheric electric fields in thunderstorms through radio emission from cosmic-ray induced air showers
P. Schellart et al. - Physical Review Letters, 24 April 2015

Brain Eating Ameba Found in Louisiana Drinking Water

Late Wednesday, the Louisiana Department of Health and Hospitals (DHH) confirmed the presence of the Naegleria fowleri ameba in the St. Bernard Parish Water System at the site of a leaking sampling station. The water system, which serves 44,000 residents in St. Bernard Parish, was tested by DHH as part of the State's new public drinking water surveillance program. 

Naegleria fowleri ameba
Credit:  CDC/ Dr. Govinda S. Visvesvara

DHH notified the water system and local officials Wednesday evening. The Department asked the water system to conduct a 60-day chlorine burn to ensure that any remaining ameba in the system are eliminated. Parish President Dave Peralta confirmed that the system would conduct the burn out of an abundance of caution.

Based on current monthly chloramine residual compliance reports, the water system has met the requirements with Louisiana rules for chloramine disinfectant levels set forth by the 2013 by emergency rule and additional requirements in 2014 by the Louisiana Legislature. Five other sites on the system tested negative for the ameba and one site did not meet the required level of disinfectant.

Tap water in St. Bernard Parish is safe for residents to drink, but the Department urges residents to avoid getting water in their noses. Naegleria fowleri is an ameba that occurs naturally in freshwater.

As Naegleria fowleri infections are extremely rare, testing for this ameba in public drinking water is still relatively new and evolving. Fewer than 10 deaths in the United States have been traced back to the ameba, with three occurring in Louisiana over the last several years. The ameba was identified in St. Bernard Parish Water System in the summer of 2013; the U.S. Centers for Disease Control and Prevention (CDC) confirmed that the system no longer tested positive for the presence of the ameba in February 2014.

DHH conducts sampling of public drinking water systems for Naegleria fowleri each summer when temperatures rise. So far, DHH has tested 12 other systems for the ameba and still awaiting lab results for each.

Naegleria fowleri causes a disease called primary amebic meningoencephalitis (PAM), which is a brain infection that leads to the destruction of brain tissue. In its early stages, symptoms of PAM may be similar to bacterial meningitis.

DHH Safe Drinking Water Program staff sampled seven sites along the St. Bernard Parish Water System. Two of the seven sites tested positive for the ameba. One positive test was at a site at the water treatment plant before the water was treated. The second positive test occurred at 948 Angela Street, which may have been contaminated by ground water due to a leak at the sampling station. Chlorine levels at the site of the positive sample did meet the 0.5 mg/l requirement. The Department will continue to consult with the water system and the CDC.

The Department requested that the water system conduct a 60-day free chlorine burn in the water system. The chlorine burn will help reduce biofilm, or organic buildup, throughout the water system and will kill the ameba. The parish has agreed to conduct this precautionary measure. 



Precautionary Measures for Families

According to the CDC, every resident can take simple steps to help reduce their risk of Naegleria fowleri infection. Individuals should focus on limiting the amount of water going up their nose. Preventative measures recommended by the CDC include the following:

DO NOT allow water to go up your nose or sniff water into your nose when bathing, showering, washing your face, or swimming in small hard plastic/blow-up pools.

DO NOT jump into or put your head under bathing water (bathtubs, small hard plastic/blow-up pools); walk or lower yourself in.

DO NOT allow children to play unsupervised with hoses or sprinklers, as they may accidentally squirt water up their nose. Avoid slip-n-slides or other activities where it is difficult to prevent water going up the nose.

DO run bath and shower taps and hoses for five minutes before use to flush out the pipes. This is most important the first time you use the tap after the water utility raises the disinfectant level.

DO keep small hard plastic/blow-up pools clean by emptying, scrubbing and allowing them to dry after each use.

DO use only boiled and cooled, distilled or sterile water for making sinus rinse solutions for neti pots or performing ritual ablutions.

DO keep your swimming pool adequately disinfected before and during use. 

Adequate disinfection means:

Pools: free chlorine at 1 to 3 parts per million (ppm) and pH 7.2 to 7.8, and
Hot tubs/spas: free chlorine 2 to 4 parts per million (ppm) or free bromine 4 to 6 ppm and pH 7.2 to 7.8.

If you need to top off the water in your swimming pool with tap water, place the hose directly into the skimmer box and ensure that the filter is running. Do not top off the pool by placing the hose in the body of the pool.

Residents should continue these precautions until testing no longer confirms the presence of the ameba in the water system. Residents will be made aware when that occurs. For further information on preventative measures, please visit the CDC website here: http://www.cdc.gov/parasites/naegleria/prevention.html 

Sunday, July 26, 2015

Is a Universal Flu Vaccine Close?

A team of American researchers have discovered a particle cocktail capable of challenging influenza strains not even contained in its formula, potentially paving the path to a universal vaccine.
Credit: Thinkstock

Each year, seasonal influenza affects around 10% of European citizens, causing hundreds of thousands of hospitalisations across the continent. And while vaccines do exist, the highly variable nature of the influenza virus means sensitive groups like children and the elderly have to get vaccinated every year.

Since these vaccines are based on predictions of the evolution of virus strains, mismatches occur quite frequently – which explains why the development of a universal vaccine, capable of tackling all variations of the virus, has been high of researchers’ agendas for years. Most recently in 2015, the strain has changed at last minute, making the vaccine less effective than initially expected.

A new study conducted on mice has just brought researchers at the United States’ National Institute of Allergy and Infectious Diseases (NIAID) one step closer to this achievement. By presenting a cocktail of flu proteins to the immune system, the team found out that they can induce immunity to strains that the animals have never encountered.

‘For a decade or more, it has been a big dream of the influenza community to develop a universal influenza vaccine, one that would provide you protection against multiple current or future strains of influenza, whether they are from humans or animals,’ study researcher Jeff Taubenberger, a pathologist and infectious-disease specialist at NIAID, said. ‘What we have done is design a strategy where you don’t have to think about matching the vaccine antigen to the virus at all.’

To get to this result, the team used a virus-like particle vaccine cocktail that expressed four of the 16 common H proteins (H1, H3, H5 and H7). H1 and H3 have been the major causes of human seasonal flu since 1918, while H5 and H7 have caused flu outbreaks among bird populations which had pandemic potential.

‘What we got was really kind of unexpected and kind of remarkable,’ Taubenberger said. ‘Almost all of the animals that received the novel vaccine survived, including mice infected with the 1918 influenza virus, H5N1 or H7N9 bird influenza viruses, and importantly mice that were challenged with viruses that expressed hemagglutinin subtypes that were not in the vaccine at all, viruses that expressed H2, H6, H10, and H11. You are challenging the mice with viruses that have a completely different protein on its surface that are not in the vaccine, so the mice should theoretically not have immunity to it.’

About 95 percent of the mice administered with the mix were found to be protected against the eight strains of flu tested. This level of protection surpassed the expectations of the team, to the point that they are still unsure how it even works. Unlike in other vaccines, it would seem that the antibody response is not the main reason the new spray works: T cells, a type of white blood cell, might also be playing a role, according to Taubenberger.

The researchers are now investigating how the vaccine works, and they already demonstrated that it was effective for at least 6 months. They're also testing it in ferrets, which are the animals most often used to mimic how humans catch and resist the flu. If those tests show promising results, human safety trials for the new vaccine could begin next year, with clinical trials for effectiveness starting the year after that, Taubenberger said.


Contacts and sources:
CORDIS

Based on a study published in the online open-access journal of the American Society for Microbiology, mBio.  http://mbio.asm.org/content/6/4/e01044-15

Clues about Black Holes’ Diet - Video

Using archival data from the Sloan Digital Sky Survey, and the XMM-Newton and Chandra X-ray telescopes, a team of astronomers have discovered a gigantic black hole, which is probably destroying and devouring a massive star in its vicinity. With a mass of 100 million times more than our Sun, this is the largest black hole caught in this act so far. The results of this study are published in a paper in the journal Monthly Notices of the Royal Astronomical Society.

A snapshot image from a computer simulation of a star disrupted by a supermassive black hole. The red-orange plumes show the debris of the star after its passage near the black hole (located close to the bottom left corner of the image). About half of the disrupted star moves in elliptical orbits around the black hole and forms an accretion disc which eventually shines brightly in optical and X-ray wavelengths. 
Credit: J. Guillochon (Harvard University) and E. Ramirez-Ruiz (University of California).

Andrea Merloni and members of his team, from the Max-Planck Institute for Extraterrestrial Physics (MPE) in Garching, near Munich, were exploring the huge archive of the Sloan Digital Sky Survey (SDSS) in preparation for a future X-ray satellite mission. The SDSS has been observing a large fraction of the night sky with its optical telescope. In addition, spectra (where light is dispersed across wavelengths, allowing astronomers to deduce properties like composition and temperature) have been taken of distant galaxies and black holes.

These plots show two SDSS spectra of the object; the different luminosities as a function of wavelength between the two epochs are clearly visible. In particular, the red dashed vertical lines show the hydrogen Balmer lines which dramatically change their shape: in the red spectrum they are much broader, which provides a "fingerprint" signature of the accretion onto a central black hole.


Credit: © SDSS/MPE. Click for a larger image

For a variety of reasons, the spectra of some objects were taken more than once. And when the team was looking at one of the objects with multiple spectra, they were struck by an extraordinary change in one of the objects under study, with the catalogue number SDSS J0159+0033, a galaxy in the constellation ofCetus. The huge distance to the galaxy means that we see it as it was 3.5 billion years ago.

“Usually distant galaxies do not change significantly over an astronomer’s lifetime, i.e. on a timescale of years or decades,” explains Andrea Merloni, “but this one showed a dramatic variation of its spectrum, as if the central black hole had switched on and off.”

This happened between 1998 and 2005, but nobody had noticed the odd behaviour of this galaxy until late last year, when two groups of scientists preparing the next (fourth) generation of SDSS surveys independently stumbled across these data.

Luckily enough, the two flagship X-ray observatories, the ESA-led XMM-Newton and the NASA-led Chandra took snapshots of the same area of the sky close in time to the peak of the flare, and again about ten years later. This gave the astronomers unique information about the high-energy emission that reveals how material is processed in the immediate vicinity of the central black hole.

Gigantic black holes are at home in the nuclei of large galaxies all around us. Most astronomers believe that they grew to the enormous sizes that we can observe today by feeding mostly on interstellar gas from their surroundings, which is unable to escape the immense gravitational pull. Such a process takes place over a very long time (tens to hundreds of millions of years), and is capable of turning a small black hole created in the explosion of a heavy star into the super-heavyweight monsters that lurk at the centre of galaxies.

However, galaxies also contain a huge number of stars. Some unlucky ones may happen to pass too close to the central black hole, where they are destroyed and eventually swallowed by the black hole. If this is compact enough, the strong, tidal gravitational forces tear the star apart in a spectacular way. Subsequently bits and pieces swirl into the black hole and thus produce huge flares of radiation that can be as luminous as all of the rest of the stars in the host galaxy for a period of a few months to a year. These rare events are called Tidal Disruption Flares (TDF).

Merloni and his collaborators quite quickly realised that 'their' flare matched almost perfectly all the expectations of this model. Moreover, because of the serendipitous nature of the discovery, they realised that this was an even more peculiar system than those which had been found through active searches until now. With an estimated mass of 100 million solar masses, this is the biggest black hole caught in the act of star-tearing so far.

However, the sheer size of the system is not the only intriguing aspect of this particular flare; it is also the first one for which scientists can assume with some degree of certainty that the black hole was on a more standard 'gas diet' very recently (a few tens of thousands of years). This is an important clue to finding out which sort of food black holes mostly live on.

This computer simulation of the disruption of a star by a black hole shows the formation of an accretion disk of stellar material spiralling into the black hole. This sequence shows an early stage in the formation of the disk. The stellar material is coloured according to its temperature, with red being colder and purple hotter.

Credit: J. Guillochon and E. Ramirez Ruiz

"Louis Pasteur said: 'Chance favours the prepared mind' - but in our case, nobody was really prepared," marvels Merloni. "We could have discovered this unique object already ten years ago, but people did not know where to look. It is quite common in astronomy that progress in our understanding of the cosmos is helped by serendipitous discoveries. And now we have a better idea of how to find more such events, and future instruments will greatly expand our reach."

In less than two years’ time a new powerful X-ray telescope eROSITA, which is currently being built at MPE, will be put into orbit on the Russian-German SRG satellite. It will scan the entire sky with the right cadence and sensitivity needed to discover hundreds of new tidal disruption flares. Big optical telescopes are also being designed and built with the goal of monitoring the variable sky, and will greatly contribute to solving the mystery of black hole eating habits. Astronomers will have to be prepared to catch these dramatic last acts of a star's life. But however prepared they’ll be, the sky will be full of new surprises.



Contacts and sources:
Dr Hannelore Hämmerle
Dr Andrea Merloni
Max-Planck-Institut für extraterrestrische Physik


Citation:  "A tidal disruption flare in a massive galaxy? Implications for the fuelling mechanisms of nuclear black holes", A. Merloni, T. Dwelly, M. Salvato, A. Georgakakis, J. Greiner, M. Krumpe, K. Nandra, G. Ponti, A. Rau, Monthly Notices of the Royal Astronomical Society, Oxford University Press.

Bats Do It, Dolphins Do It. Now Humans Can Use Ultrasonic Echolocation Too

Berkeley physicists have used graphene to build lightweight ultrasonic loudspeakers and microphones, enabling people to mimic bats or dolphins’ ability to use sound to communicate and gauge the distance and speed of objects around them.

More practically, the wireless ultrasound devices complement standard radio transmission using electromagnetic waves in areas where radio is impractical, such as underwater, but with far greater fidelity than current ultrasound or sonar devices. They can also be used to communicate through objects, such as steel, that electromagnetic waves can’t penetrate.

A canyon or western pipistrelle bat (Parastrellus hesperus), a common Northern California species of bat recorded with the new ultrasonic microphone.
  http://www.flickr.com/photos/danielpneal/
Photo courtesy of Daniel Neal

“Sea mammals and bats use high-frequency sound for echolocation and communication, but humans just haven’t fully exploited that before, in my opinion, because the technology has not been there,” said UC Berkeley physicist Alex Zettl. “Until now, we have not had good wideband ultrasound transmitters or receivers. These new devices are a technology opportunity.”

Speakers and microphones both use diaphragms, typically made of paper or plastic, that vibrate to produce or detect sound, respectively. The diaphragms in the new devices are graphene sheets a mere one atom thick that have the right combination of stiffness, strength and light weight to respond to frequencies ranging from subsonic (below 20 hertz) to ultrasonic (above 20 kilohertz). Humans can hear from 20 hertz up to 20,000 hertz, whereas bats hear only in the kilohertz range, from 9 to 200 kilohertz. The grapheme loudspeakers and microphones operate from well below 20 hertz to over 500 kilohertz.

Graphene consists of carbon atoms laid out in a hexagonal, chicken-wire arrangement, which creates a tough, lightweight sheet with unique electronic properties that have excited the physics world for the past 20 or more years.

“There’s a lot of talk about using graphene in electronics and small nanoscale devices, but they’re all a ways away,” said Zettl, who is a senior scientist at Lawrence Berkeley National Laboratory and a member of the Kavli Energy NanoSciences Institute, operated jointly by UC Berkeley and Berkeley Lab. “The microphone and loudspeaker are some of the closest devices to commercial viability, because we’ve worked out how to make the graphene and mount it, and it’s easy to scale up.” 

Zettl, UC Berkeley postdoctoral fellow Qin Zhou and colleagues describe their graphene microphone and ultrasonic radio in a paper appearing online this week in the Proceedings of the National Academy of Sciences.

Radios and rangefinders

Two years ago, Zhou built loudspeakers using a sheet of graphene for the diaphragm, and since then has been developing the electronic circuitry to build a microphone with a similar graphene diaphragm.

One big advantage of graphene is that the atom-thick sheet is so lightweight that it responds well to the different frequencies of an electronic pulse, unlike today’s piezoelectric microphones and speakers. This comes in handy when using ultrasonic transmitters and receivers to transmit large amounts of information through many different frequency channels simultaneously, or to measure distance, as in sonar applications.

“Because our membrane is so light, it has an extremely wide frequency response and is able to generate sharp pulses and measure distance much more accurately than traditional methods,” Zhou said.

Graphene membranes are also more efficient, converting over 99 percent of the energy driving the device into sound, whereas today’s conventional loudspeakers and headphones convert only 8 percent into sound. Zettl anticipates that in the future, communications devices like cellphones will utilize not only electromagnetic waves – radio – but also acoustic or ultrasonic sound, which can be highly directional and long-range.

“Graphene is a magical material; it hits all the sweet spots for a communications device,” he said.

Bat chirps

When Zhou told his wife, Jinglin Zheng, about the ultrasound microphone, she suggested he try to capture the sound of bats chirping at frequencies too high for humans to hear. So they hauled the microphone to a park in Livermore and turned it on. When they slowed down the recording to one-eighth normal speed, converting the high frequencies to an audio range humans can hear, they were amazed at the quality and fidelity of the bat vocalizations.

An atom-thick layer of carbon atoms, called graphene (black mesh), provides the vibrating diaphragm for both an ultrasonic microphone and loudspeaker.

 UC Berkeley image.

“This is lightweight enough to mount on a bat and record what the bat can hear,” Zhou said.

Bat expert Michael Yartsev, a newly hired UC Berkeley assistant professor of bioengineering and member of the Helen Wills Neuroscience Institute, said, “These new microphones will be incredibly valuable for studying auditory signals at high frequencies, such as the ones used by bats. The use of graphene allows the authors to obtain very flat frequency responses in a wide range of frequencies, including ultrasound, and will permit a detailed study of the auditory pulses that are used by bats.”

Zettl noted that audiophiles would also appreciate the graphene loudspeakers and headphones, which have a flat response across the entire audible frequency range.

“A number of years ago, this device would have been darn near impossible to build because of the difficulty of making free-standing graphene sheets,” Zettl said. “But over the past decade the graphene community has come together to develop techniques to grow, transport and mount graphene, so building a device like this is now very straightforward; the design is simple.”

The work was supported by the U.S. Department of Energy, the Office of Naval Research and the National Science Foundation. Other co-authors were Zheng, Michael Crommie, a UC Berkeley professor of physics, and Seita Onishi.



Contacts and sources:
Robert Sanders 
UC Berkeley

Were Icy Comets Storks For Life On Earth?

Early Earth was an inhospitable place where the planet was often bombarded by comets and other large astrophysical bodies.

Some of those comets contained complex prebiotic materials, such as amino acids and peptides (chains of amino acids), which are some of the most basic building blocks of life on Earth.

This simulation depicts a comet hitting the young Earth, generating the amino acids necessary for life.

Credit: Matthew Genge/Imperial College London

“The survivability of these compounds under impact conditions is mostly unknown,” said Lawrence Livermore’s Nir Goldman, who recently received a NASA grant to continue his astrobiology research. “Our research hopes to answer these questions and give an indication for what types of potentially life-building compounds would be produced under these conditions.”

Basically, Goldman is trying to figure out if life on Earth really did come from out of this world.

Goldman’s early research found that the impact of icy comets crashing into Earth billions of years ago could have produced a variety of small prebiotic or life-building compounds. His work using quantum simulations predicted that the simple molecules found in comets (such as water, ammonia, methanol and carbon dioxide) could have supplied the raw materials, and the impact with early Earth would have yielded an abundant supply of energy to drive the synthesis of compounds like protein forming amino acids. 

In later work, researchers from Imperial College in London and University of Kent conducted a series of experiments very similar to Goldman’s simulations in which a projectile was fired using a light gas gun into a typical cometary ice mixture. The result: Several different types of amino acids formed.

“Impact events could have not only delivered prebiotic precursors to the primitive planet, but the sudden increase in pressure and temperature from the impact itself was likely a driving factor in synthesizing their assembly into these primary structures,” Goldman said.

Specifically, this new $500,000 grant will fund quantum simulation studies to understand aqueous mixtures of pre-formed amino acids under impact conditions. Goldman’s current efforts will extend his previous work by looking at one step higher in complexity, where extreme pressures and temperatures from impact could induce the formation of more intricate chemical structures like peptide chains or simple proteins.

“Large astrophysical bodies such as comets likely already contain more complex prebiotic materials, like amino acids. It’s possible that pre-existing amino acids would have experienced additional impacts during periods of heavy bombardment on early Earth,” Goldman said. “Our quantum simulations hope to help answer these questions, and to give an indication as to what set of thermodynamic conditions promotes their assembly into larger structures.”

How and when prebiotic organic material appeared on early Earth has been debated for close to 60 years, starting with the seminal Miller-Urey experiments, which showed that amino acids could be produced in aqueous mixtures subjected to electrical discharges, simulating lightning on early Earth.

Large bodies from space are carriers of prebiotic materials. Previous analysis of dust samples from comet Wild 2 has shown the presence of the amino acid glycine in the captured material. In addition, dipeptides (i.e., an amino acid dimer) likely exist in interstellar ices. Assuming survival upon delivery to Earth, these could have acted as catalysts in the formation of a number of prebiotic compounds, including sugars and enzymes.

“Our predictions will help spur future collaboration with experimental groups to characterize the synthesis of primary biomaterials due to exposure to extreme pressures and temperatures,” Goldman said.



Contacts and sources:
By Anne M. Stark 
Lawrence Livermore Lab