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Saturday, March 25, 2017

The World's Largest Diamond Foil

Friedrich-Alexander Universität Erlangen Nürnberg (FAU) material researchers have come a step closer to their goal of providing large diamond foils for practical applications. In a test reactor, they have succeeded in producing the world’s largest diamond foil with a diameter of 28 centimetres. Diamond foils can be used as ultimate wear protection in industrial applications and for research into thermoelectric power generation – an emerging market.

Diamonds are not only considered valuable, but also virtually indestructible. They are one of the hardest natural materials in our universe. Consequently it is not surprising that producing diamond foils has become a key area in materials science research, particularly as these layers feature extreme hardness and wear resistance, exceptional chemical inertness and maximum thermal conductivity. Unfortunately, coating substrates directly with crystalline diamond is only possible on a limited range of materials. 

The size of a pizza: the world’s largest diamond foil 

Image: FAU


The research group ‘Ultra Hard Coatings’ at FAU’s Chair of Materials Science and Technology of Metals has developed a process of growing diamond coatings on silicon substrates which can be used on materials which are not suitable for direct coating. They have now succeeded in producing the world’s largest diamond foil with a diameter of 28 centimetres. 

‘By scaling up the manufacturing process, we have demonstrated that we can produce diamond foils in future as a semi-finished product for industry even in large dimensions,’ explains Dr. Stefan Rosiwal, head of the Ultra Hard Coatings research group at the Chair of Materials Science and Technology of Metals. ‘In these diamond layers, we can adjust the diamond grain size, the electrical conductivity and thermal conductivity by varying the manufacturing parameters by many orders of magnitude.’

The procedure

Over several days, the diamond foils are produced in a test reactor in which a 40-micrometre thick diamond layer – approximately the thickness of a human hair – is grown on a silicon disc with a diameter of 30 centimetres. The diamond foils are produced in a low-pressure atmosphere of hydrogen and two percent methane under wires which are heated to 2000 degrees Celsius. After the coating process, a short pulse laser is used to introduce a circular fracture site with a diameter of 28.5 centimetres into the diamond surface. This makes it possible to separate the deposited layer as a very smooth diamond foil from the silicon substrate.

Potential applications

This procedure has opened up a whole new range of other possible applications. Virtually any substrate material can be coated with diamond film by means of a suitable joining technique. The extremely hard and smooth diamond foils can, for example, protect component surfaces against wear and tear. Research has already shown that diamond foils can give 100% protection for water turbines which are exposed to erosion from sand. 

Now that researchers have demonstrated diamond foil manufacturing processes successfully on a larger scale, this opens up opportunities for coating industrial components directly in a more cost effective way. Such industrial components include wear-resistant layers for mechanical seals in pumps as well as the production of stable diamond electrodes for highly efficient water purification and disinfection systems. 

These innovative diamond electrode systems are used for washing and disinfecting oranges after harvesting in southern Europe, removing putrefying bacteria from the surface of the fruit and saving up to 80% water. In the future, the technology could be used on container ships or sewage treatment plants. Diamond electrodes may even help in washing machines by keeping clothes clean and fresh at significantly lower temperatures.



Contacts and sources: 
Stefan M. Rosiwal
Friedrich-Alexander Universität Erlangen Nürnberg (FAU) 

*The findings were published under the titles ‘Mechanical properties of micro- and nanocrystalline diamond foils’ and ‘Thermoelectric transport properties of boron-doped nanocrystalline diamond foils’ in the renowned scientific journals ‘Philosophical Transactions A’ doi:10.1098/rsta.2014.0136 and ‘Carbon’ doi:10.1016/j.carbon.2014.10.002.
 

Scientists Unveil a Giant Leap for Anti-Aging

University of New South Wales (UNSW) researchers have made a discovery that could lead to a revolutionary drug that actually reverses ageing, improves DNA repair and could even help NASA get its astronauts to Mars.

In a paper published in Science today, the team identifies a critical step in the molecular process that allows cells to repair damaged DNA.

Their experiments in mice suggest a treatment is possible for DNA damage from ageing and radiation. It is so promising it has attracted the attention of NASA, which believes the treatment can help its Mars mission.

While our cells have an innate capability to repair DNA damage ? which happens every time we go out into the sun, for example - their ability to do this declines as we age.

This is professor David Sinclair and his UNSW team.

Credit:Britta Campion

The scientists identified that the metabolite NAD+, which is naturally present in every cell of our body, has a key role as a regulator in protein-to-protein interactions that control DNA repair.

Treating mice with a NAD+ precursor, or "booster," called NMN improved their cells' ability to repair DNA damage caused by radiation exposure or old age.

"The cells of the old mice were indistinguishable from the young mice, after just one week of treatment," said lead author Professor David Sinclair of UNSW School of Medical Sciences and Harvard Medical School Boston.

Human trials of NMN therapy will begin within six months.

"This is the closest we are to a safe and effective anti-ageing drug that's perhaps only three to five years away from being on the market if the trials go well," says Sinclair, who maintains a lab at UNSW in Sydney.

What it means for astronauts, childhood cancer survivors, and the rest of us:

The work has excited NASA, which is considering the challenge of keeping its astronauts healthy during a four-year mission to Mars.

Even on short missions, astronauts experience accelerated ageing from cosmic radiation, suffering from muscle weakness, memory loss and other symptoms when they return. On a trip to Mars, the situation would be far worse: five per cent of the astronauts' cells would die and their chances of cancer would approach 100 per cent.

Professor Sinclair and his UNSW colleague Dr Lindsay Wu were winners in NASA's iTech competition in December last year.

"We came in with a solution for a biological problem and it won the competition out of 300 entries," Dr Wu says.

Cosmic radiation is not only an issue for astronauts. We're all exposed to it aboard aircraft, with a London-Singapore-Melbourne flight roughly equivalent in radiation to a chest x-ray.

In theory, the same treatment could mitigate any effects of DNA damage for frequent flyers. The other group that could benefit from this work is survivors of childhood cancers.

Dr Wu says 96 per cent of childhood cancer survivors suffer a chronic illness by age 45, including cardiovascular disease, Type 2 diabetes, Alzheimer's disease, and cancers unrelated to the original cancer.

"All of this adds up to the fact they have accelerated ageing, which is devastating," he says.

"It would be great to do something about that, and we believe we can with this molecule."

An anti-ageing pill could be on the horizon:

For the past four years, Professor Sinclair and Dr Wu have been working on making NMN into a drug substance with their companies MetroBiotech NSW and MetroBiotech International.

The human trials will begin this year at Brigham and Women's Hospital, in Boston.

The findings on NAD+ and NMN add momentum to the exciting work the UNSW Laboratory for Ageing Research has done over the past four years.

They've been looking at the interplay of a number of proteins and molecules and their roles in the ageing process.

They had already established that NAD+ could be useful for treating various diseases of ageing, female infertility and also treating side effects of chemotherapy.

In 2003, Professor Sinclair made a link between the anti-ageing enzyme SIRT1 and resveratrol, a naturally occurring molecule found in tiny quantities in red wine.

"While resveratrol activates SIRT1 alone, NAD+ boosters activate all seven sirtuins, SIRT1-7, and should have an even greater impact on health and longevity," he says.


Contacts and sources: 
Gabrielle Dunlevy
University of New South Wales (UNSW) 

Upper Part of Earth’s Magnetic Field Reveals a Dramatic Past

Satellites have been mapping the upper part of the Earth magnetic field by collecting data for three years and found some amazing features about the Earth’s crust. The result is the release of highest resolution map of this field seen from space to date. This ‘lithospheric magnetic field’ is very weak and therefore difficult to detect and map from space. But with the Swarm satellites it has been possible.

“By combining Swarm measurements with historical data from the German CHAMP satellite, and using a new modelling technique, it was possible to extract the tiny magnetic signals of crustal magnetization with unprecedented accuracy,” said professor Nils Olsen from the Technical University of Denmark (DTU), one of the team of scientists behind the new map that has just been released at a Swarm Science Meeting in Banff, Canada.

Most of the Earth magnetic field is generated at depths greater than 3000 km by the movement of molten iron in the outer core. The remaining 6 percent – including the ‘lithospheric magnetic field' - is partly due to electrical currents in space surrounding Earth, and partly due to magnetised rocks in the upper lithosphere – the rigid outer part of Earth, consisting of the crust and upper mantle.

Magnetic field model/Magnetic anomaly
Credit: ESA

Swarm is a constellation of three identical satellites launched by the European Space Agency (ESA) to track and study the Earth’s magnetic field.

Possible meteorite impact

The new map shows detailed variations in this field caused by geological structures in Earth’s crust. One of these anomalies occurs in Central African Republic, centred around the city of Bangui, where the magnetic field is significantly sharper and stronger. The cause for this anomaly is still unknown, but scientists speculate that it may be the result of a meteorite impact there some 540 million years ago.

Evidence of flipping poles

The new map also reveals more details about the Earth's magnetic field that has flipped its polarity many times over the millennia. The magnetic field is in a permanent state of flux. Magnetic north wanders, and every few hundred thousand years the polarity flips so that a compass would point south instead of north.


Credit: European Space Agency, ESA

When new crust is generated through volcanic activity, mainly along the ocean floor, iron-rich minerals in the solidifying magma are oriented towards magnetic north, thus capturing a ‘snapshot’ of the magnetic field in the state it was in when the rocks cooled.

Since magnetic poles flip back and forth over time, the solidified minerals form ‘stripes’ on the seafloor and provide a record of Earth’s magnetic history.

Latest map of the lithospheric magnetic field by Swarm shows detailed variations in this field more precisely than previous satellite-based reconstructions, caused by geological structures in Earth’s crust. One of these anomalies occurs in Central African Republic, centred on the city of Bangui, where the magnetic field is significantly sharper and stronger. The cause for this anomaly is still unknown, but some scientists speculate that it may be the result of a meteorite impact more than 540 million years ago.
Credit: ESA

“These magnetic stripes are evidence of pole reversals and analysing the magnetic imprints of the ocean floor allows the reconstruction of past core field changes. They also help to investigate tectonic plate motions,” said Dhananjay Ravat from the University of Kentucky in the USA.

“The new map defines magnetic field features down to about 250 km and will help investigate geology and temperatures in Earth’s lithosphere.”

ESA’s Swarm mission manager, Rune Floberghagen, added:

“Understanding the crust of our home planet is no easy feat. Measurements from space have great value as they offer a sharp global view on the magnetic structure of our planet’s rigid outer shell.”

Earth’s magnetic field can be thought of as a huge cocoon, protecting us from cosmic radiation and charged particles that bombard our planet in solar wind. Without it, life as we know it would not exist.



Contacts and sources:
Nils Olsen, Professor -head of Geomagnetism, DTU Space
Technical University of Denmark (DTU)

3D Bioprinted Human Cartilage Cells Can Be Implanted

Swedish researchers at Chalmers University of Technology and Sahlgrenska Academy have successfully induced human cartilage cells to live and grow in an animal model, using 3D bioprinting. The results will move development closer to a potential future in which it will be possible to help patients by giving them new body parts through 3D bioprinting.

The results were recently presented in the journal Plastic and Reconstructive Surgery Global Open.

“This is the first time anyone has printed human-derived cartilage cells, implanted them in an animal model and induced them to grow,” says Paul Gatenholm, professor of biopolymer technology at Chalmers University of Technology.

The illustration shows the formation of blood vessels, i.e., vascularisation, in the bioprinted material implanted in an animal model. 
Illustration: Philip Krantz

Among else, Professor Gatenholm leads the research team working with the new biomaterial based on nanocellulose at the Wallenberg Wood Science Center. He has been working with Lars Kölby, senior lecturer at Sahlgrenska Academy at University of Gothenburg and specialist consultant with the Department of Plastic Surgery at Sahlgrenska University Hospital.

The researchers printed a hydrogel of nanocellulose mixed with human-derived cartilage cells – a so called construct. They used a 3D bioprinter manufactured by Cellink, a Gothenburg-based startup firm whose bio-ink is a result of research by Paul Gatenholm. Immediately after printing, the construct was implanted in mice.

The researchers can report three positive results of the animal study:
1. Human cartilage tissue has grown in an animal model.
2. Vascularisation, i.e., the formation of blood vessels, between the materials.
3. Strong stimulation of proliferation and neocartilage formation by human stem cells.

“What we see after 60 days is something that begins to resemble cartilage. It is white and the human cartilage cells are alive and producing what they are supposed to. We have also been able to stimulate the cartilage cells by adding stem cells, which clearly promoted further cell division,” says Lars Kölby.

Sandra Ferreyra Vega, master's student in biotechnology at Chalmers University of Technology, Matteo Amoroso, a plastic surgeon at Sahlgrenska University Hospital, and Paul Gatenholm, professor of biopolymer technology at Chalmers, working with a 3D bioprinter. 

Photo: Mats Tiborn

“We now have proof that the 3D printed hydrogel with cells can be implanted. It grows in mice and, in addition, blood vessels have formed in it,” says Paul Gatenholm.

Collaboration has been a key component and critical to the success of the project. Scientists in two different disciplines have successfully crossed academic lines to find a common goal where they could combine their skills in a fruitful way.

“Often, it is like this: we clinicians work with problems and researchers work with solutions. If we can come together, there is a chance of actually solving some of the problems we are wrestling with – and in this way, patients benefit from the research,” says Lars Kölby.

Paul Gatenholm is careful to point out that the results he and Lars Kölby’s team are now able to report do not involve any short cut to bioprinted organs.

“With what we have done, the research has taken a step forward towards someday, we hope, being able to bioprint cells that become body parts for patients. This is how you have to work when it comes to this kind of pioneering activity: one small step at a time. Our results are not a revolution – but they are a gratifying part of an evolution!”



Contacts and sources:
Chalmers University of Technology

Citation: In Vivo Chondrogenesis in 3D Bioprinted Human Cell-laden Hydrogel Constructs
Möller, Thomas; Amoroso, Matteo; Hägg, Daniel; Brantsing, Camilla; Rotter, Nicole; Apelgren, Peter; Lindahl, Anders; Kölby, Lars; Gatenholm, Paul
Plastic and Reconstructive Surgery - Global Open:
February 2017 - Volume 5 - Issue 2 - p e1227
doi: 10.1097/GOX.0000000000001227

First International NanoCar Race: Watch Molecular Grand Prix Live April 28

French scientists are organizing the world's first ever molecular Grand Prix in which nanocars will race.

Nanocars will compete for the first time ever during an international molecule-car race on April 28-29, 2017 in Toulouse (south-western France). The vehicles, which consist of a few hundred atoms, will be powered by minute electrical pulses during the 36 hours of the race, in which they must navigate a racecourse made of gold atoms, and measuring a maximum of a 100 nanometers in length.

These "NanoCars" or molecule-cars can have real wheels, an actual chassis...and are propelled by the energy of electric pulses! Nothing is visible to the naked eye, however a unique microscope located in Toulouse will make it possible to follow the race. A genuine scientific prowess and international human adventure, the race is a one-off event, and will be broadcast live on the web, as well as at the Quai des Savoirs, science center in Toulouse.  Watch the race live on April 28 from 11 a.m.

They will square off beneath the four tips of a unique microscope located at the CNRS's Centre d'élaboration de matériaux et d'études structurales (CEMES) in Toulouse. The race, which was organized by the CNRS, is first and foremost a scientific and technological challenge, and will be broadcast live on the YouTube Nanocar Race channel. Beyond the competition, the overarching objective is to advance research in the observation and control of molecule-machines.

Credit; CNRS (Délégation Paris Michel-Ange)

More than just a competition, the Nanocar Race is an international scientific experiment that will be conducted in real time, with the aim of testing the performance of molecule-machines and the scientific instruments used to control them. The years ahead will probably see the use of such molecular machinery—activated individually or in synchronized fashion—in the manufacture of common machines: atom-by-atom construction of electronic circuits, atom-by-atom deconstruction of industrial waste, capture of energy...The Nanocar Race is therefore a unique opportunity for researchers to implement cutting-edge techniques for the simultaneous observation and independent maneuvering of such nano-machines.


Credit; CNRS (Délégation Paris Michel-Ange)

The experiment began in 2013 as part of an overview of nano-machine research for a scientific journal, when the idea for a car race took shape in the minds of CNRS senior researcher Christian Joachim (now the director of the race) and Gwénaël Rapenne, a Professor of chemistry at Université Toulouse III - Paul Sabatier. Three years later, the nanocars are operational and ready to face off on the circuit's gold surface. There were numerous challenges in organizing this race, from selecting the racecourse, which must accommodate all types of molecule-cars, to adapting the scanning tunneling microscope. 

The participating teams also had to overcome a series of difficult tasks (depositing and visualizing the molecules beneath the microscope), as well as meet numerous criteria (the molecules’ structure and form of propulsion) in order to participate in this race. Of the nine teams that applied before the end of May 2016, six were selected, and four will take their place at the 4-tip microscope’s starting line on April 28, 2017 for the 36-hour race in Toulouse.

The challenges facing researchers in the race will be so many steps forward in novel fields in chemistry and physics. In the process, each team will build up new skills, data, and know-how that will one day contribute to the development of surface chemistry (which enables chemical synthesis directly on a particular surface), or in the new science of surfaces known as membrane science, which makes it possible to deposit a molecule-machine on the surface of a cell, or to control the movement of a single molecule in a liquid.

The CEMES-CNRS microscope is the only one in the world allowing four different experimenters to work on the same surface. The development of such multi-tip microscopes will enable synchronizing a great number of molecule-machines in order to increase capacity, for instance for storing energy or capturing it from a hot metallic surface. A genuine "atom technology" is dawning.


The rules of the race:

- The racecourse: 20 nm + one 45° turn + 30 nm + one 45° turn + 20 nm, for a total of 100 nm

- 36h maximum duration

- Authorization to change one's nanocar in case of an accident

- Pushing one's nanocar is forbidden

- One sector of the gold surface per team

- Maximum 6 hours to clean one's portion of the course before starting

- No tip changes allowed during the 36 hours


Contacts and sources:
CNRS (Délégation Paris Michel-Ange)

A Stem’s ‘Sense of Self’ Contributes to Shape: Mathematical Framework Explains Diverse Plant Stem Forms

It is well known that as plants grow, their stems and shoots respond to outside signals like light and gravity. But if plants all have similar stimuli, why are there so many different stem shapes? Why does a weeping willow grow downwards while nearby poison ivy shoots upwards?

Using simple mathematical ideas, researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) constructed a framework that explains and quantifies the different shapes of plant stems.

The research is published in the Journal of the Royal Society Interface.

Credit; SEAS

“We have combined, in one theory, a plant’s ability to sense itself and its environment while being constrained by gravity and its elastic nature,” said L. Mahadevan, the Lola England de Valpine Professor of Applied Mathematics, of Organismic and Evolutionary Biology, and of Physics. “By accounting for these factors, we can explain the range of shapes seen in nature without the need for complex growth strategies. This, in turn, implies that the diversity of morphologies seen in your garden may follow from very simple causes.”


Credit; SEAS

Mahadevan is also a core faculty member of the Wyss Institute for Biologically Inspired Engineering at Harvard.

Mahadevan and coauthor Raghunath Chelakkot describe plant shoots as ‘sentient’ meaning they can sense their own shape and the direction of gravity and light through mechanochemical pathways.

When these pathways are triggered by stimuli, one part of the shoot may grow relative to another and change shape. The shoots of the weeping willow, for example, try to grow upwards, away from gravity and towards light. But, because they are so soft, the shoots sag under the weight of gravity and cascade towards the ground. On the other hand, poison ivy shoots start by growing downwards before turning upwards.

How organisms sense and respond to these outside signals is important to understanding everything from plant growth to human development.

“Different organs in our body grow and take on their characteristic shapes by responding to both internal and external signals, such as gravity,” said Mahadevan. “We do not yet understand how large-scale shape changes arise from a combination of sensing and growth, and our study attempts to look at one example of this.”

The research was supported in part by the MacArthur Foundation.




Contacts and sources:
Leah Burrows
Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) 

Friday, March 24, 2017

Laser Activated Gold Pyramids Could Deliver Drugs, DNA into Cells Without Harm

The ability to deliver cargo like drugs or DNA into cells is essential for biological research and disease therapy but cell membranes are very good at defending their territory. Researchers have developed various methods to trick or force open the cell membrane but these methods are limited in the type of cargo they can deliver and aren’t particularly efficient.

Now, researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have developed a new method using gold microstructures to deliver a variety of molecules into cells with high efficiency and no lasting damage. The research is published in ACS Nano.

“Being able to effectively deliver large and diverse cargos directly into cells will transform biomedical research,” said Nabiha Saklayen, a PhD candidate in the Mazur Lab at SEAS and first author of the paper. “However, no current single delivery system can do all the things you need to do at once. Intracellular delivery systems need to be highly efficient, scalable, and cost effective while at the same time able to carry diverse cargo and deliver it to specific cells on a surface without damage. It’s a really big challenge.”

A scanning-electron microscope image of chemically-fixed HeLa cancer cells on the substrate. The tips of the pyramids create tiny holes in the cell membranes, allowing molecular cargo to diffuse into the cells.
Image courtesy of Harvard SEAS

In previous research, Saklayen and her collaborators demonstrated that gold, pyramid-shaped microstructures are very good at focusing laser energy into electromagnetic hotspots. In this research, the team used a fabrication method called template stripping to make surfaces — about the size of a quarter — with 10 million of these tiny pyramids.

"The beautiful thing about this fabrication process is how simple it is,” said Marinna Madrid, coauthor of the paper and PhD candidate in the Mazur Lab. “Template-stripping allows you to reuse silicon templates indefinitely. It takes less than a minute to make each substrate, and each substrate comes out perfectly uniform. That doesn't happen very often in nanofabrication."

The team cultured HeLa cancer cells directly on top of the pyramids and surrounded the cells with a solution containing molecular cargo.

Using nanosecond laser pulses, the team heated the pyramids until the hotspots at the tips reached a temperature of about 300 degrees Celsius. This very localized heating — which did not affect the cells — caused bubbles to form right at the tip of each pyramid. These bubbles gently pushed their way into the cell membrane, opening brief pores in the cell and allowing the surrounding molecules to diffuse into the cell.

Nanosecond pulses of laser heat the gold-covered pyramids, causing bubbles to form right at the tip of each pyramid. These bubbles gently push their way into the cell membrane, opening brief pores and allowing molecules to diffuse in. Actual pyramids are uniform in height.


(Video courtesy of Nabiha Saklayen/Harvard SEAS)

“We found that if we made these pores very quickly, the cells would heal themselves and we could keep them alive, healthy and dividing for many days,” Saklayen said.

Each HeLa cancer cell sat atop about 50 pyramids, meaning the researchers could make about 50 tiny pores in each cell. The team could control the size of the bubbles by controlling the laser parameters and could control which side of the cell to penetrate.

The molecules delivered into the cell were about the same size as clinically relevant cargos, including proteins and antibodies.

Next, the team plans on testing the methods on different cell types, including blood cells, stem cells and T cells. Clinically, this method could be used in ex vivo therapies, where unhealthy cells are taken out of the body, given cargo like drugs or DNA, and reintroduced into the body.

“This work is really exciting because there are so many different parameters we could optimize to allow this method to work across many different cell types and cargos,” said Saklayen. “It’s a very versatile platform.”

Harvard’s Office of Technology Development has filed patent applications and is considering commercialization opportunities.

“It’s great to see how the tools of physics can greatly advance other fields, especially when it may enable new therapies for previously difficult to treat diseases," said Eric Mazur, the Balkanski Professor of Physics and Applied Physics and senior author of the paper.

This research was supported by the National Science Foundation and the Howard Hughes Medical Institute. It was coauthored by Marinus Huber, Marinna Madrid, Valeria Nuzzo, Daryl Inna Vulis, Weilu Shen, Jeffery Nelson, Arthur McClelland and Alexander Heisterkamp



Contacts and sources:
Leah Burrows
 Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) 

Why the Steep Rise of the Bernese Alps

The striking North Face of the Bernese Alps is the result of a steep rise of rocks from the depths following a collision of two tectonic plates. This steep rise gives new insight into the final stage of mountain building and provides important knowledge with regard to active natural hazards and geothermal energy. The results from researchers at the University of Bern and ETH Zürich are being published in the "Scientific Reports" specialist journal.

Mountains often emerge when two tectonic plates converge, where the denser oceanic plate subducts beneath the lighter continental plate into the earth’s mantle according to standard models. But what happens if two continental plates of the same density collide, as was the case in the area of the Central Alps during the collision between Africa and Europe?

Vertical cross-section through the Alps 15 million years ago. The European plate subducted under the African plate cannot go any deeper, as a result its upper mantle section sinks away to the north (slab rollback). The European lower crust detaches from the mantle and buoyancy forces allow the European crust to rise steeply. 

Schematic drawing © M. Herwegh, Institute for Geology, University of Bern

Geologists and geophysicists at the University of Bern and ETH Zürich examined this question. They constructed the 3D geometry of deformation structures through several years of surface analysis in the Bernese Alps. With the help of seismic tomography, similar to ultrasound examinations on people, they also gained additional insight into the deep structure of the earth’s crust and beyond down to depths of 400 km in the earth’s mantle.
Viscous rocks from the depths

A reconstruction based on this data indicated that the European crust’s light, crystalline rocks cannot be subducted to very deep depths but are detached from the earth’s mantle in the lower earth’s crust and are consequently forced back up to the earth’s surface by buoyancy forces. Steep fault zones are formed here, which push through the earth’s crust and facilitate the steep rise of rocks from the depths. There are textbook examples of these kinds of fault zones in the Hasli valley, where they appear as scars in form of morphological incisions impressively cutting through the glacially polished granite landscape.

The Eiger, Mönch and Jungfrau are part of the striking front of the northern ridge of the Bernese Alps, which was formed due to the steep rise of rocks from the depths. 
Foto © M. Herwegh, Institute for Geology, University of Bern.


The detachment of the earth’s crust and mantle takes place at a depth of 25-30 kilometres. This process is triggered by the slow sinking and receding of the European plate in the upper earth’s mantle towards the north. In specialist terminology, this process is called slab rollback. The high temperatures at these depths make the lower crust’s rocks viscous, where they can subsequently be forced up by buoyant uplift forces.

Steep couloirs on the Arpelistock and Ärelenhoren (Hasli valley) show the steep fault zones (red lines) which were topographically shaped by erosion. 

Foto © M. Herwegh, Institute for Geology, University of Bern

Together with surface erosion, it is this steep rise of the rocks from lower to mid-crustal levels which is responsible for the Bernese Alps’ steep north front today (Titlis – Jungfrau region – Blüemlisalp range). The uplift data in the range of one millimetre per year and today’s earthquake activity indicate that the process of uplift from the depths is still in progress. However, erosion on the earth’s surface causes continuous ablation which is why the Alps do not carry on growing upwards endlessly.
Important for natural hazards and geothermal energy

View of the granite bastion north of Grimsel Lake with glacially polished granite surfaces being heavily dissected by morphological incisions. These furrows (see arrows) are all the result of steep fault zones, which originated at a depth of 20 kilometres. Due to uplift and erosion, they are recognisable today on the earth’s surface as couloirs in the topography.
 Photo © M. Herwegh, Institute for Geology, University of Bern.

The analysis of the steep fault zones are not just of scientific interest though. The seismic partly still active faults are responsible for the rocks weathering more intensively on the surface and therefore landslides and debris flows occurring, for example in the Halsi valley in the extremely steep areas of the Spreitlaui or Rotlaui. The serious debris flows in the Guttannen area are based, among other things, on this structural preconditioning of the host rocks. 

The leakage of warm hydrothermal water, which it is important to explore for geothermal energy and the 2050 energy policy, can be traced directly back to the brittle fracturing of the upper earth’s crust and the seeping in of cold surface waters. The water is heated up in the depths and arrives at the surface again through the steep fault zones – for example, in the Grimsel region. In this sense, the new findings lead to a deeper understanding of surface processes, which influence our infrastructures, for example the transit axes (rail, roads) through the Alps.

 

Contacts and sources:
University of Bern 

Citation: Marco Herwegh, Alfons Berger, Roland Baumberger, Philip Wehrens & Edi Kissling: «Large-Scale Crustal-Block-Extrusion During Late Alpine Collision», Scientific Reports, 24.03.2017, doi: 10.1038/s41598-017-00440-0

Record Breaking Discovery: Astronomers Identify Purest, Most Massive Brown Dwarf

An international team of astronomers has identified a record breaking brown dwarf (a star too small for nuclear fusion) with the 'purest' composition and the highest mass yet known. The object, known as SDSS J0104+1535, is a member of the so-called halo – the outermost reaches - of our Galaxy, made up of the most ancient stars. The scientists report the discovery in Monthly Notices of the Royal Astronomical Society.

Brown dwarfs are intermediate between planets and fully-fledged stars. Their mass is too small for full nuclear fusion of hydrogen to helium (with a consequent release of energy) to take place, but they are usually significantly more massive than planets.

An artist's impression of the new pure and massive brown dwarf. 
Credit: John Pinfield. 


Located 750 light years away in the constellation of Pisces, SDSS J0104+1535 is made of gas that is around 250 times purer than the Sun, so consists of more than 99.99% hydrogen and helium. Estimated to have formed about 10 billion years ago, measurements also suggest it has a mass equivalent to 90 times that of Jupiter, making it the most massive brown dwarf found to date.

It was previously not known if brown dwarfs could form from such primordial gas, and the discovery points the way to a larger undiscovered population of extremely pure brown dwarfs from our Galaxy's ancient past.

The research team was led by Dr ZengHua Zhang of the Institute of Astrophysics in the Canary Islands. He said: "We really didn't expect to see brown dwarfs that are this pure. Having found one though often suggests a much larger hitherto undiscovered population - I'd be very surprised if there aren't many more similar objects out there waiting to be found."

SDSS J0104+1535 has been classified as an L type ultra-subdwarf using its optical and near-infrared spectrum, measured using the European Southern Observatory's Very Large Telescope (VLT). This classification was based on a scheme very recently established by Dr Zhang.



Contacts andn sources:
Dr Robert Massey,Royal Astronomical Society
Dr ZengHua Zhang, Instituto de Astrofísica de Canarias,
 Prof David Pinfield, Centre for Astrophysics Research, University of Hertfordshire,

Citation: "Primeval very low-mass stars and brown dwarfs - II. The most metal-poor substellar object", Z. H. Zhang, D. Homeier, D. J. Pinfield, N. Lodieu, H. R. A. Jones, F. Allard, and Ya. V. Pavlenko, Monthly Notices of the Royal Astronomical Society, published by Oxford University Press, in press.

Another Immune System Link Found That Science Said Didn't Exist

The University of Virginia School of Medicine has again shown that a part of the body thought to be disconnected from the immune system actually interacts with it, and that discovery helps explain cases of male infertility, certain autoimmune diseases and even the failure of cancer vaccines.

Scientists developing such vaccines may need to reconsider their work in light of the new findings or risk unintentionally sabotaging their own efforts. UVA's Kenneth Tung, MD, said that many vaccines likely are failing simply because researchers are picking the wrong targets - targets that aren't actually foreign to the immune system and thus won't provoke the desired immune responses.

Overturning Orthodoxy

Tung, of UVA's Beirne B. Carter Center for Immunology Research, and a team of collaborators have discovered an unexpected interaction between men's testes and the immune system. While science textbooks insist the testes are barricaded from the immune system by an impenetrable wall of cells, the researchers have determined there's actually a very small door in that wall, a door that appears to open in only one direction.

Kenneth Tung, M.D., of the University of Virginia School of Medicine, has discovered an unknown connection between men's testes and the immune system -- a link that could explain infertility and the failure of cancer vaccines.

Credit: Josh Barney | UVA Health System


The team discovered that the testes release some, but not all, of the antigens - substances that can spur an immune response - that are created during the production of sperm. Because the testes release these antigens naturally, the immune system ignores them. That's a normal, healthy response, but it also may explain why cancer vaccines are failing. Cancer vaccines target antigens, so if vaccine developers rely on antigens that are ignored by the immune system, the vaccine won't work.

"In essence, we believe the testes antigens can be divided into those which are sequestered [behind the barrier] and those that are not," Tung said. "Antigens which are not sequestered would not be very good cancer vaccine candidates."

The good news is that doctors can determine which antigens a patient's cancer cells release. By targeting sequestered antigens - the ones unknown to the immune system - doctors could greatly increase vaccines' chances of success.

Treating Infertility

The finding also may prove important for couples seeking to have children. Up to 12 percent of men who suffer from infertility have an autoimmune response to their own reproductive cells. That means their immune systems are attacking their sperm, essentially. Tung and his collaborators shed light on what may be happening, showing that a particular step during the creation of sperm is responsible for determining whether the sperm antigens will spark an immune response. Cells called "regulatory T cells" then help control the immune system's response to the non-sequestered antigens. In men who are infertile because of an autoimmune disorder, something is going wrong with the process, leading the immune system to attack when it shouldn't. With that knowledge, doctors may be able to develop new treatments for the autoimmune disorders and the resulting infertility.

Rethinking the Immune System

The discovery of the unknown immune interaction comes less than two years after UVA's Jonathan Kipnis and Antoine Louveau rewrote textbooks when they discovered that the brain has a direct connection to the immune system, a connection long thought not to exist. That discovery could have profound effects in the quest to defeat diseases ranging from Alzheimer's to multiple sclerosis.



Contacts and sources:
Josh Barney
The University of Virginia Health System

Citation: Egress of sperm autoantigen from seminiferous tubules maintains systemic tolerance. http://dx.doi.org/10.1172/JCI89927

 

Farmers in Roman Empire Converted to Hun Lifestyle – and Vice Versa

New archaeological analysis suggests people of Western Roman Empire switched between Hunnic nomadism and settled farming over a lifetime. Findings may be evidence of tribal encroachment that undermined Roman Empire during 5th century AD, contributing to its fall.

Marauding hordes of barbarian Huns, under their ferocious leader Attila, are often credited with triggering the fall of one of history’s greatest empires: Rome.

Historians believe Hunnic incursions into Roman provinces bordering the Danube during the 5th century AD opened the floodgates for nomadic tribes to encroach on the empire. This caused a destabilisation that contributed to collapse of Roman power in the West.

Example of a modified skull, a practice assumed to be Hunnic that may have been appropriated by local farmers within the bounds of the Western Roman Empire.
Credit: Erzsébet Fóthi, Hungarian Natural History Museum Budapest

According to Roman accounts, the Huns brought only terror and destruction. However, research from the University of Cambridge on gravesite remains in the Roman frontier region of Pannonia (now Hungary) has revealed for the first time how ordinary people may have dealt with the arrival of the Huns.

Biochemical analyses of teeth and bone to test for diet and mobility suggest that, over the course of a lifetime, some farmers on the edge of empire left their homesteads to become Hun-like roaming herdsmen, and consequently, perhaps, took up arms with the tribes.

Other remains from the same gravesites show a dietary shift indicating some Hun discovered a settled way of life and the joys of agriculture – leaving their wanderlust, and possibly their bloodlust, behind.

Lead researcher Dr Susanne Hakenbeck, from Cambridge’s Department of Archaeology, says the Huns may have brought ways of life that appealed to some farmers in the area, as well learning from and settling among the locals. She says this could be evidence of the steady infiltration that shook an empire.

“We know from contemporary accounts that this was a time when treaties between tribes and Romans were forged and fractured, loyalties sworn and broken. The lifestyle shifts we see in the skeletons may reflect that turmoil,” says Hakenbeck.

“However, while written accounts of the last century of the Roman Empire focus on convulsions of violence, our new data appear to show some degree of cooperation and coexistence of people living in the frontier zone. Far from being a clash of cultures, alternating between lifestyles may have been an insurance policy in unstable political times.”

For the study, published today in the journal PLOS ONE, Hakenbeck and colleagues tested skeletal remains at five 5th-century sites around Pannonia, including one in a former civic centre as well as rural homesteads.

The team analysed the isotope ratios of carbon, nitrogen, strontium and oxygen in bones and teeth. They compared this data to sites in central Germany, where typical farmers of the time lived, and locations in Siberia and Mongolia, home to nomadic herders up to the Mongol period and beyond.

The results allowed researchers to distinguish between settled agricultural populations and nomadic animal herders in the former Roman border area through isotopic traces of diet and mobility in the skeletons.

All the Pannonian gravesites not only held examples of both lifestyles, but also many individuals that shifted between lifestyles in both directions over the course of a lifetime. “The exchange of subsistence strategies is evidence for a way of life we don’t see anywhere else in Europe at this time,” says Hakenbeck.

She says there are no clear lifestyle patterns based on sex or accompanying grave goods, or even ‘skull modification’ – the binding of the head as a baby to create a pointed skull – commonly associated with the Hun.

“Nomadic animal herding and skull modification may be practices imported by Hun tribes into the bounds of empire and adopted by some of the agriculturalist inhabitants.”

The diet of farmers was relatively boring, says Hakenbeck, consisting primarily of plants such as wheat, vegetables and pulses, with a modicum of meat and almost no fish.

The herders’ diet on the other hand was high in animal protein and augmented with fish. They also ate large quantities of millet, which has a distinctive carbon isotope ratio that can be identified in human bones. Millet is a hardy plant that was hugely popular with nomadic populations of central Asia because it grows in a few short weeks.

Roman sources of the time were dismissive of this lifestyle. Ammianus Marcellinus, a Roman official, wrote of the Hun that they “care nothing for using the ploughshare, but they live upon flesh and an abundance of milk.”

“While Roman authors considered them incomprehensibly uncivilised and barely human, it seems many of citizens at the edge of Rome’s empire were drawn to the Hun lifestyle, just as some nomads took to a more settled way of life,” says Hakenbeck.

However, there is one account that hints at the appeal of the Hun, that of Roman politician Priscus. While on a diplomatic mission to the court of Attila, he describes encountering a former merchant who had abandoned life in the Empire for that of the Hun enemy as, after war, they “live in inactivity, enjoying what they have got, and not at all, or very little, harassed.”



'Super Halos' Enveloped Milky Way-Like Galaxies in Early Universe

By harnessing the extreme sensitivity of the Atacama Large Millimeter/submillimeter Array (ALMA), astronomers have directly observed a pair of Milky Way-like galaxies seen when the universe was only eight percent of its current age. These progenitors of today’s giant spiral galaxies are surrounded by "super halos" of hydrogen gas that extend many tens of thousands of light-years beyond their dusty, star-filled disks.

Astronomers initially detected these galaxies by studying the intense light from even-more-distant quasars. As this light travels through an intervening galaxy on its way to Earth, it can pick up the unique spectral signature from the galaxy’s gas. This technique, however, normally prevents astronomers from seeing the actual light emitted by the galaxy, which is overwhelmed by the much brighter emission from the background quasar.

Artist impression of a progenitor of Milky Way-like galaxy in the early universe with a background quasar shinning through a 'super halo' of hydrogen gas surrounding the galaxy. New ALMA observations of two such galaxies reveal that these vast halos extend well beyond the galaxies' dusty, star-forming disks. The galaxies were initially found by the absorption of background quasar light passing through the galaxies. ALMA was able to image the ionized carbon in the galaxies' disks, revealing crucial details about their structures. 
Credit: A. Angelich (NRAO/AUI/NSF)

"Imagine a tiny firefly next to a high-power search light. That’s what astronomers are up against when it comes to observing these youthful versions of our home galaxy," said Marcel Neeleman a postdoctoral fellow at the University of California, Santa Cruz, and lead author on a paper appearing in the journal Science. "We can now see the galaxies themselves, which gives us an amazing opportunity to learn about the earliest history of our own galaxy and others like it."

With ALMA, the astronomers were finally able to observe the natural millimeter-wavelength "glow" emitted by ionized carbon in the dense and dusty star-forming regions of the galaxies. This carbon signature, however, is considerably offset from the gas first detected by quasar absorption. This extreme separation indicates that the galaxies’ gas content extends well beyond their star-filled disks, suggesting that each galaxy is embedded in a monstrous halo of hydrogen gas.

"We had expected we would see faint emission right on top of the quasar, and instead we saw bright galaxies at large separations from the quasar," said J. Xavier Prochaska, professor of astronomy and astrophysics at UC Santa Cruz and coauthor of the paper. The separation from the quasar to the observed galaxy is about 137,000 light-years for one galaxy and about 59,000 light-years for the other.


Credit: Produced by Alexandra Angelich (NRAO/AUI/NSF); Written and narrated by Charles Blue (NRAO/AUI/NSF); Animations and footage courtesy of Alexandra Angelich (NRAO/AUI/NSF); NASA/Goddard Space Flight Center/Cruz deWilde and the Advanced Visualization Laboratory at the National Center for Supercomputing and B. O'Shea, M. Norman; ESO/C.Malin; Science images courtesy of M. Neeleman & J. Xavier Prochaska; Keck Observatory; Music by Geodesium

According to the researchers, the neutral hydrogen gas revealed by its absorption of quasar light is most likely part of a large halo or perhaps an extended disk of gas around the galaxy. "It's not where the star formation is, and to see so much gas that far from the star-forming region means there is a large amount of neutral hydrogen around the galaxy," Neeleman said.

Composite ALMA and optical image of a young Milky Way-like galaxy 12 billion light-years away and a background quasar 12.5 billion light-years away. Light from the quasar passed through the galaxy's gas on its way to Earth, revealing the presence of the galaxy to astronomers. New ALMA observations of the galaxy's ionized carbon (green) and dust continuum (blue) emission show that the dusty, star-forming disk of the galaxy is vastly offset from the gas detected by quasar absorption at optical wavelengths (red). This indicates that a massive halo of gas surrounds the galaxy. The optical data are from the Keck I Telescope at the W.M. Keck Observatory. 
Credit: ALMA (ESO/NAOJ/NRAO), M. Neeleman & J. Xavier Prochaska; Keck Observatory


The new ALMA data show that these young galaxies are already rotating, which is one of the hallmarks of the massive spiral galaxies we see in the universe today. The ALMA observations further reveal that both galaxies are forming stars at moderately high rates: more than 100 solar masses per year in one galaxy and about 25 solar masses per year in the other.

"These galaxies appear to be massive, dusty, and rapidly star-forming systems, with large, extended layers of gas," Prochaska said.

"ALMA has solved a decades-old question on galaxy formation," said Chris Carilli, an astronomer with the National Radio Astronomy Observatory in Socorro, N.M., and co-author on the paper. "We now know that at least some very early galaxies have halos that are much more extended that previously considered, which may represent the future material for galaxy growth."

The galaxies, which are officially designated ALMA J081740.86+135138.2 and ALMA J120110.26+211756.2, are each about 12 billion light-years from Earth. The background quasars are each roughly 12.5 billion light-years from Earth.

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.



Contacts and sources:
Charles Blue
National Radio Astronomy Observatory (NRAO)


This research is presented in a paper titled "[C II] 158-μm emission from the host galaxies of damped Lyman alpha systems," by M. Neeleman et al., scheduled for publication in the journal Science on 24 March 2017.

Sea Ice Reaches Record Lows at Both Poles

Arctic sea ice appears to have reached on March 7 a record low wintertime maximum extent, according to scientists at NASA and the NASA-supported National Snow and Ice Data Center (NSIDC) in Boulder, Colorado. And on the opposite side of the planet, on March 3 sea ice around Antarctica hit its lowest extent ever recorded by satellites at the end of summer in the Southern Hemisphere, a surprising turn of events after decades of moderate sea ice expansion.

The March 7, 2017, Arctic sea ice maximum extent was a record low, due to warmer-than-average temperatures, winds unfavorable to ice expansion, and a series of storms. Antarctic sea ice also broke a record with its annual minimum extent on March 3.

Credits: NASA's Goddard Space Flight Center

On Feb. 13, the combined Arctic and Antarctic sea ice numbers were at their lowest point since satellites began to continuously measure sea ice in 1979. Total polar sea ice covered 6.26 million square miles (16.21 million square kilometers), which is 790,000 square miles (2 million square kilometers) less than the average global minimum extent for 1981-2010 – the equivalent of having lost a chunk of sea ice larger than Mexico.

These line graphs plot monthly deviations and overall trends in polar sea ice from 1979 to 2017 as measured by satellites. The top line shows the Arctic; the middle shows Antarctica; and the third shows the global, combined total. The graphs depict how much the sea ice concentration moved above or below the long-term average. (They do not plot total sea ice concentration.) Arctic and global sea ice totals have moved consistently downward over 38 years. Antarctic trends are more muddled, but they do not offset the great losses in the Arctic.



Credits: Joshua Stevens/NASA Earth Observatory
More information from NASA's Earth Observatory

The ice floating on top of the Arctic Ocean and surrounding seas shrinks in a seasonal cycle from mid-March until mid-September. As the Arctic temperatures drop in the autumn and winter, the ice cover grows again until it reaches its yearly maximum extent, typically in March. The ring of sea ice around the Antarctic continent behaves in a similar manner, with the calendar flipped: it usually reaches its maximum in September and its minimum in February.

This winter, a combination of warmer-than-average temperatures, winds unfavorable to ice expansion, and a series of storms halted sea ice growth in the Arctic. This year’s maximum extent, reached on March 7 at 5.57 million square miles (14.42 million square kilometers), is 37,000 square miles (97,00 square kilometers) below the previous record low, which occurred in 2015, and 471,000 square miles (1.22 million square kilometers) smaller than the average maximum extent for 1981-2010.

On March 7, 2017, Arctic sea ice hit a record low wintertime maximum extent in 2017. At 5.57 million square miles, it is the lowest maximum extent in the satellite record, and 455,600 square miles below the 1981 to 2010 average maximum extent. 
Credits: NASA Goddard's Scientific Visualization Studio/L. Perkins


“We started from a low September minimum extent,” said Walt Meier, a sea ice scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “There was a lot of open ocean water and we saw periods of very slow ice growth in late October and into November, because the water had a lot of accumulated heat that had to be dissipated before ice could grow. The ice formation got a late start and everything lagged behind – it was hard for the sea ice cover to catch up.”

The Arctic’s sea ice maximum extent has dropped by an average of 2.8 percent per decade since 1979. The summertime minimum extent losses are nearly five times larger: 13.5 percent per decade. Besides shrinking in extent, the sea ice cap is also thinning and becoming more vulnerable to the action of ocean waters, winds and warmer temperatures.

This year’s record low sea ice maximum extent might not necessarily lead to a new record low summertime minimum extent, since weather has a great impact on the melt season’s outcome, Meier said. “But it’s guaranteed to be below normal.”

On March 3, 2017, the sea ice cover around the Antarctic continent shrunk to its lowest yearly minimum extent in the satellite record, in a dramatic shift after decades of moderate sea ice expansion.
Credits: NASA Goddard's Scientific Visualization Studio/L. Perkins

In Antarctica, this year’s record low annual sea ice minimum of 815,000 square miles (2.11 million square kilometers) was 71,000 square miles (184,000 square kilometers) below the previous lowest minimum extent in the satellite record, which occurred in 1997.

Antarctic sea ice saw an early maximum extent in 2016, followed by a very rapid loss of ice starting in early September. Since November, daily Antarctic sea ice extent has continuously been at its lowest levels in the satellite record. The ice loss slowed down in February.

This year’s record low happened just two years after several monthly record high sea ice extents in Antarctica and decades of moderate sea ice growth.

Operation IceBridge, NASA’a aerial survey of polar ice, flies over a lead, or opening in the sea ice cover, near the Alaskan coast on March 11, 2017.

Credits: NASA/Jeremy Harbeck

“There’s a lot of year-to-year variability in both Arctic and Antarctic sea ice, but overall, until last year, the trends in the Antarctic for every single month were toward more sea ice,” said Claire Parkinson, a senior sea ice researcher at Goddard. “Last year was stunningly different, with prominent sea ice decreases in the Antarctic. To think that now the Antarctic sea ice extent is actually reaching a record minimum, that’s definitely of interest.”

Meier said it is too early to tell if this year marks a shift in the behavior of Antarctic sea ice.

“It is tempting to say that the record low we are seeing this year is global warming finally catching up with Antarctica,” Meier said. “However, this might just be an extreme case of pushing the envelope of year-to-year variability. We’ll need to have several more years of data to be able to say there has been a significant change in the trend.”



Contacts and sources:
By Maria-José Viñas
NASA's Earth Science News

Related
NSIDC announcement
Data visualization: Minimum Antarctic Sea Ice 2017
Data visualization: Arctic Daily Sea Ice Concentration from Arctic Minimum 2016 to Arctic Maximum 2017

"2016 Arctic Sea Ice Wintertime Extent Hits Another Record Low" (March 28, 2016)
"NASA Study Shows Global Sea Ice Diminishing, Despite Antarctic Gains" (Feb. 10, 2015)
"Arctic Sea Ice Annual Minimum Ties Second Lowest on Record" (Sept. 15, 2016)

Under the Dead Sea, Warnings of Dire Drought


Nearly 1,000 feet below the bed of the Dead Sea, scientists have found evidence that during past warm periods, the Mideast has suffered drought on scales never recorded by humans -- a possible warning for current times. Thick layers of crystalline salt show that rainfall plummeted to as little as a fifth of modern levels some 120,000 years ago, and again about 10,000 years ago. Today, the region is drying again as climate warms, and scientists say it will get worse. The new findings may cause them to rethink how much worse, in this already thirsty and volatile part of the world.

"All the observations show this region is one of those most affected by modern climate change, and it's predicted to get dryer. What we showed is that even under natural conditions, it can become much drier than predicted by any of our models," said lead author Yael Kiro, a geochemist at Columbia University's Lamont-Doherty Earth Observatory. The findings were just published in an early online edition of the journal Earth and Planetary Science Letters.

Deep below the seabed, drilling revealed thick layers of salt, precipitated out during past warm, dry periods. In this specimen, transparent crystals (left) formed on what was then the bottom during winter; finer white ones (right) formed on the water surface in summer and later sank.

Credit: Yael Kiro/Lamont-Doherty Earth Observatory

The landlocked Dead Sea, straddling Israel, Jordan and Palestinian lands, is earth's lowest spot on land. Its current shoreline lies about 1,300 feet below sea level, and its floor extends down another 900 feet. Fed mainly by the Jordan River drainage, which extends also into Syria and Lebanon, it is a dead end for water, and so is extremely salty; its Biblical name in Hebrew is Yām ha-Melah, the sea of salt. In recent years, its level has dropped about four feet a year. But hot, dry weather is not the main cause yet; rather, booming populations in the region need more water than ever, and people are sucking so much from the watershed, very little reaches the Dead Sea, where evaporation is outweighing input.


The U.N. Food and Agriculture Organization estimates that much of the region already has per capita water availability only a tenth of the world average. Rainfall has declined about 10 percent since 1950, and existing climate models say it could sink another 20 percent this century, even as population continues to grow. Israel is meeting demand by desalinating Mediterranean seawater, but poorer, landlocked Jordan and the Palestinian territories are desperate for more. In adjoining Syria, a record 1998-2012 drought likely stoked by climate change is believed to have helped spark the ongoing civil war, which has now claimed more than 500,000 lives and infected neighboring nations.

In 2010, scientists from a half-dozen nations drilled 1,500 feet into the deepest part of the seabed, bringing up a cross section of deposits recording 200,000 years of regional climate history--the longest such archive in the Mideast. (Around-the-clock drilling went for 40 days and 40 nights -- perhaps a respectful bow to the rainfall of the Biblical Flood.) The cores revealed alternating layers of mud washed in with runoff during wet times, and crystallized salt, precipitated out during dry times when the water receded. This instantly made it clear that the region has suffered epic dry periods, but the core was not analyzed in great detail until now.

The new study shows that the salt accumulated rapidly?an estimated half-inch per year in many cases. The researchers spotted two striking periods. About halfway down they found salty layers some 300 feet thick, indicating a long-term drop below the sea's current level. This came in a period between ice ages, 115,000 to 130,000 years ago, when variations in Earth's orbit brought temperatures about 4 degrees hotter those of the 20th century?equivalent to what is projected for the end of the 21st century. The lake refilled when glaciers readvanced in sub-polar regions and the Mideast climate cooled and became moister. The cores show a similar drop in lake level just 6,000 to 10,000 years ago, following the most recent ice age, when temperatures were probably a bit cooler than now.

The landlocked Dead Sea is shrinking rapidly. A new study suggests it has largely dried up in the past during natural warm periods, suggesting that human-influenced climate change could make the surrounding region much more arid than it already is.

Credit: David Shankbone/Wikimedia Commons


The chemistry of tiny fluid bubbles within the salt allowed the researchers to extrapolate rainfall and runoff patterns of these periods. They calculated that runoff to the Dead Sea generally declined 50 to 70 percent compared to today, dwarfing current projections for this century. In the most extreme periods, it went down 80 percent, and this lasted for decades to centuries at a time. The declines are probably linked to broader shifts in atmospheric flow patterns. Storms coming in from the Mediterranean could have slackened, as they appear to be doing today; and then as now, higher temperatures increase evaporation of moisture from the land.

To alleviate growing water shortages, Jordan plans to break ground next year on a canal to bring in water from the Red Sea for desalination; leftover brine would be dumped into the Dead Sea, possibly stabilizing its level. But the project is controversial, because it could cause drastic environmental changes in both seas, and could still leave much of the rest of the region with inadequate water.

"The Dead Sea is wasting away today because humans are using up all its fresh water sources," said Steven Goldstein, a geochemist at Lamont-Doherty and coauthor of the paper who helped oversee the 2010 drilling. "Our study shows that in the past, without any human intervention, the fresh water nearly stopped flowing. This means that if it keeps getting hotter now, it could stop running again. This time, it would affect millions of people."




Contacts and sources: 
Kevin Krajick
The Earth Institute/Lamont-Doherty Earth Observatory  


The paper, "Relationships between lake-level changes and water and salt budgets in the Dead Sea during extreme aridities in the Eastern Mediterranean,"  
 

Salmon with a Side of Side Effects

Salmon lead a fairly varied life. The adult fish live in the sea but swim upstream into rivers to reproduce and lay their eggs in gravel beds in the upper reaches. This is where the young hatch, grow for a while in the clean, oxygen-rich water, and then set off towards the sea. To breed the popular edible fish, farmers have to provide different living conditions depending on the age of the fish.

Chilean fish farmers base their approach on the natural life cycle of the salmon. In the clear rivers which flow from the central ridge of the Andes towards the Pacific, they have installed a few hundred hatcheries for the eggs and the youngest animals. Slightly larger salmon live in cages in the lakes of the South American country, and the adults then move into similar accommodation anchored in the sea just off the coast. In 2012, Chile's aquacultures used this method to produce some 820,000 tonnes of salmon with a total value of just under five billion US dollars. For years, the country has been ranked second behind Norway in the list of key salmon producers worldwide.

Salmon aquaculture on Río Niltre, a small river in Chile. The youngest generation of salmon is bred here. The waste water is conducted into the river through a pipe (centre of picture). 
Photo: Norbert Kamjunke


However, this has not been without an impact on the environment. The cages for the medium and larger fish leak excrement, food residue and other substances into the country's seas and coastal waters. The companies also draw water for their hatcheries from some of the extremely clean, natural rivers. They pump it through the tanks for the young salmon before reintroducing it to the river further downstream - where it is certainly not in good condition.

Rather than clear water, it is more like a fishy broth which flows downstream from this kind of facility - which is a burden for residents, tourists and aquatic organisms. "Completely turbid water is no longer allowed to re-enter the river," reports Dr Norbert Kamjunke, a biologist at UFZ. The number of particles contained in the water must be below certain limit values. The aquacultures are now using sedimentation tanks and rotary filters to clarify their waste water. However, there are no such regulations for dissolved substances which simply flow into the water as before without any treatment or monitoring. And in huge quantities.

In an earlier study, Norbert Kamjunke and his colleagues discovered that, in facilities of this kind, around 40 tonnes of dissolved organic substances end up in the rivers for every 50 tonnes of farmed salmon. These substances, which chemists group together as Dissolved Organic Matter (DOM), include the liquid excretions from the salmon, and dissolved residues of food and excrement. "It also contains disinfectants and antibiotics," he explains. But what compounds does this cocktail contain exactly? And what impact does it have on the water? Researchers have recently investigated this in detail for the first time.

To do so, they used state-of-the-art methods of chemical analysis. Using fluorescence measurements, high-resolution mass spectrometry, and nuclear magnetic resonance spectroscopy, the researchers studied the waste water from four Chilean aquacultures and samples taken from sections of the river both upstream and downstream of the farms. They worked with colleagues from the Universidad Austral de Chile in Valdivia to take samples, with the subsequent measurements carried out at the Helmholtz Centre in Munich. "We were able to determine exactly what DOM molecules were present in the water and in what concentration," explains Norbert Kamjunke.

The investigation showed that each of the rivers naturally has a slightly different chemical fingerprint. If it flows through heavily forested areas, the water will contain a large amount of humic matter. By contrast, water in volcanic regions tends to have a high proportion of sulphur compounds. However, there are also similarities. Natural sections of river generally contain less dissolved organic material. And this limited load consists of compounds which are difficult for bacteria to break down. "Those areas are predominantly low in nutrients," summarises Norbert Kamjunke.

However, the picture changes when waste water from aquaculture is introduced. These facilities release large quantities of readily biodegradable compounds. In particular, much higher concentrations of carbohydrates, proteins and their building blocks, and lipids are present downstream of the facilities. The aquacultures therefore provide the low-nutrient rivers with a kind of fertilizer boost.

But what does this entail for the water and its inhabitants? The researchers also investigated this issue in their study. They used laser scanning microscopes to examine the slippery film that grows on stones on the river bed. Upstream of the aquacultures, these biofilms contained a large amount of microscopic algae. These organisms were much less abundant downstream, where there were many more bacteria. "But this changes the entire ecosystem," explains Norbert Kamjunke.

The algae on the bottom of the natural waters play a key role for several reasons. Firstly they produce oxygen, and secondly they provide food for countless minute grazing organisms. Gastropods, mayfly and stone fly larvae all graze this film. And they in turn are eaten by fish. "The basis of the entire food web would disappear if this algae didn't exist," explains Norbert Kamjunke. But this is not the only way in which the waste water from the aquacultures alters living conditions in the river. The bacteria downstream of the facilities use up a large amount of oxygen to break down the dissolved organic matter. Excessively low oxygen concentrations can spell the end of many species which have adapted to life in clean flowing water.

However, the high level of bacterial activity that the team measured downstream of the salmon hatcheries also cleans the water. "Nevertheless, rivers should not be misused as natural sewage treatment plants," emphasises Norbert Kamjunke. For one thing, clean and unpolluted waters and their inhabitants deserve special protection. For another thing, the water downstream of the facilities has to flow quite a distance downstream until it is clean again. The length of this stretch depends on the external circumstances. The miniature water purifiers work most effectively at high temperatures and low flow rates. An earlier study by researchers from Magdeburg showed that the bacteria had broken down the pollution around 2.7 kilometres downstream of the facility. "In winter, however, they need a much longer section of river," says Norbert Kamjunke. And this is not always available to them in the short rivers of the Andes.

The researchers therefore advocate the introduction of limit values for the DOM concentrations entering the river. Their findings in relation to the activities of the bacteria could help to specify these values in order to avoid overloading the river. The aquacultures would then have to clean their waste water more effectively before re-introducing it to the river - for example using biological filters. In principle, these are large pipes filled with stones on which biofilm grows. The waste water enters at the top and leaves at the bottom, having been clarified by the bacteria in between. "Our results also show how large these facilities would have to be," explains Norbert Kamjunke. The measured degradation rates can be used to calculate how much stone surface area is required for the desired purification efficiency.

The researchers also draw another conclusion from their study. They do not consider it advisable to install any further aquacultures on Chilean rivers. The authorities have already imposed a moratorium on new salmon farms in the country's lakes. Operators are now considering the option of moving the farming of medium-sized salmon from the lakes to the rivers. "In theory that could work," believes Norbert Kamjunke. "But from an ecological perspective, it would not be a good idea."



Contacts and sources:
Susanne Hufe, Helmholtz Centre for Environmental Research (UFZ),
Dr. Norbert Kamjunke, UFZ-Department Fließgewässerökologie

Black Hole Ejected from Center of Galaxy With Force Equivalent to Energy of 100 Million Supernovae Exploding Simultaneously

An international team of astronomers using the NASA/ESA Hubble Space Telescope have uncovered a supermassive black hole that has been propelled out of the centre of the distant galaxy 3C186. The black hole was most likely ejected by the power of gravitational waves. This is the first time that astronomers found a supermassive black hole at such a large distance from its host galaxy centre.

Though several other suspected runaway black holes have been seen elsewhere, none has so far been confirmed. Now astronomers using the NASA/ESA Hubble Space Telescope have detected a supermassive black hole, with a mass of one billion times the Sun’s, being kicked out of its parent galaxy. “We estimate that it took the equivalent energy of 100 million supernovae exploding simultaneously to jettison the black hole,” describes Stefano Bianchi, co-author of the study, from the Roma Tre University, Italy.

The galaxy 3C186, located about 8 billion years from Earth, is most likely the result of a merger of two galaxies. This is supported by arc-shaped tidal tails, usually produced by a gravitational tug between two colliding galaxies, identified by the scientists. The merger of the galaxies also led to a merger of the two supermassive black holes in their centres, and the resultant black hole was then kicked out of its parent galaxy by the gravitational waves created by the merger.

The bright, star-like looking quasar can be seen in the centre of the image. Its former host galaxy is the faint, extended object behind it.
Credit:NASA , ESA, and M. Chiaberge (STScI/ESA)


The images taken by Hubble provided the first clue that the galaxy, named 3C186, was unusual. The images of the galaxy, located 8 billion light-years away, revealed a bright quasar, the energetic signature of an active black hole, located far from the galactic core. “Black holes reside in the centres of galaxies, so it’s unusual to see a quasar not in the centre,” recalls team leader Marco Chiaberge, ESA-AURA researcher at the Space Telescope Science Institute, USA.

The team calculated that the black hole has already travelled about 35 000 light-years from the centre, which is more than the distance between the Sun and the centre of the Milky Way. And it continues its flight at a speed of 7.5 million kilometres per hour .As the black hole cannot be observed directly, the mass and the speed of the supermassive black holes were determined via spectroscopic analysis of its surrounding gas. At this speed the black hole could travel from Earth to the Moon in three minutes.
 
Although other scenarios to explain the observations cannot be excluded, the most plausible source of the propulsive energy is that this supermassive black hole was given a kick by gravitational waves unleashed by the merger of two massive black holes at the centre of its host galaxy. This theory is supported by arc-shaped tidal tails identified by the scientists, produced by a gravitational tug between two colliding galaxies.

First predicted by Albert Einstein, gravitational waves are ripples in space that are created by accelerating massive objects. The ripples are similar to the concentric circles produced when a rock is thrown into a pond. In 2016, the Laser Interferometer Gravitational-wave Observatory (LIGO) helped astronomers prove that gravitational waves exist by detecting them emanating from the union of two stellar-mass black holes, which are several times more massive than the Sun.

According to the theory presented by the scientists, 1-2 billion years ago two galaxies — each with central, massive black holes — merged. The black holes whirled around each other at the centre of the newly-formed elliptical galaxy, creating gravitational waves that were flung out like water from a lawn sprinkler. The black holes get closer over time as they radiate away gravitational energy.

 As the two black holes did not have the same mass and rotation rate, they emitted gravitational waves more strongly along one direction. When the two black holes finally merged, the anisotropic emission of gravitational waves generated a kick that shot the resulting black hole out of the galactic centre.

“If our theory is correct, the observations provide strong evidence that supermassive black holes can actually merge,” explains Stefano Bianchi on the importance of the discovery. “There is already evidence of black hole collisions for stellar-mass black holes, but the process regulating supermassive black holes is more complex and not yet completely understood.”

This illustration shows how two supermassive black holes merged to form a single black hole which was then ejected from its parent galaxy.

Panel 1: Two galaxies are interacting and finally merging with each other. The supermassive black holes in their centres are attracted to each other.

Panel 2: As soon as the supermassive black holes get close they start orbiting each other, in the process creating strong gravitational waves.

Credit:NASA, ESA /Hubble, and A. Feild/STScI

Panel 3: As they radiate away gravitational energy the black holes move closer to each other over time and finally merge.

Panel 4: If the two black holes do not have the same mass and rotation rate, they emit gravitational waves more strongly along one direction. When the two black holes finally collide, they stop producing gravitational waves and the newly merged black hole then recoils in the opposite direction to the strongest gravitational waves and is shot out of its parent galaxy.

The researchers are lucky to have caught this unique event because not every black hole merger produces imbalanced gravitational waves that propel a black hole out of the galaxy. The team now wants to secure further observation time with Hubble, in combination with the Atacama Large Millimeter/submillimeter Array (ALMA) and other facilities, to more accurately measure the speed of the black hole and its surrounding gas disc, which may yield further insights into the nature of this rare object.


 
Contacts and sources:
Marco Chiaberge, Space Telescope Science Institute
Stefano Bianchi, Roma Tre University
 Mathias Jäger, ESA/Hubble,