RESEARCH in Jülich

:: THE QUEEN OF SUPERCOMPUTERS

A Queen to be Reckoned With!

:: Neuroeconomics: Wired Differently :: Storing Energy with Silicon and Air

RESEARCH

in Jülich

The inside of the SAPHIR atmosphere simulation chamber at Jülich is 20 m long and has a diameter of 5 m. A variable roof regulates the inci- dent sunlight and protects the double-walled Teflon tube with a volume of 275 m³ inside the chamber. It can be used to simulate chemical pro- cesses in the atmosphere – for atmospheric chemists, this is a unique laboratory. Here, they can create any desired air composition and simu- late chemical processes that occur in the atmosphere under natural, but controlled conditions. Observations from the field and from airborne measuring campaigns such as PEGASOS – a Europe-wide research mission using the Zeppelin NT – can be selectively reproduced in SAPHIR. The aim is to verify and expand our understanding of the deg- radation of trace gases in the atmosphere and thus to contribute to optimizing models of air quality and climate.

:: IN THE PICTURE

:: NEWS IN BRIEF 4

:: COVER STORY 6

6 A Queen to be Reckoned With!

An audience with Europe’s queen of supercomputers

:: RESEARCH AT THE CENTRE 12

12 Wired Differently

Decision-makers use faster pathways in the brain

14 Merging Stars

A simulation explaining why stars disappear

16 Recharging After Midnight: Study on Electromobility How the electricity grid can cope with six million electric cars

18 Storing Energy with Silicon and Air A promising development in the world of batteries

:: EARLY-CAREER SCIENTISTS 20

20 From Vessels to a Network

An early-career scientist researches blood flows

:: LAST BUT NOT LEAST 22

22 Information Pathways in the Brain Imaging bundles of nerves with polarized light 23 Publication Details

CONTENTS

iOS (iPad) Or scan the QR code to download the app directly:

Android

Now also available as a magazine app!

www.fz-juelich.de/app

I

n the journal Nature Materials, an international team of researchers including physicists from Forschungszen- trum Jülich published an article on how magnetism emerges at low temperatures in one of the most impor- tant semiconductors. The scientists studied a magnetic semiconductor known as gallium manganese arsenide us- ing a method they recently developed. In the most power- ful particle accelerator worldwide, SPring-8 in Harima Sci- ence Garden City in Japan, they bombarded the material with photons. This allowed them to observe the proper- ties of electrons deep inside the material. They discov- ered that on the atomic level, the magnetism has two competing causes – a result that, for the first time, exper- imentally confirmed theoretical predictions made in the last few years.

The electrical properties of semiconductors form the basis of modern information technology. If it were possi- ble to also exploit the magnetic properties of electrons in semiconductors, information could be transported in a

more energy-efficient manner. ::

Magnetic Semiconduc- tors Under Fire

First place in Europe, fifth place world- wide: that’s our new supercomputer JUQUEEN’s current ranking in the TOP500 list of the fastest supercom- puters in the world – a result that makes us proud. JUQUEEN is the first supercomputer in Europe to reach a peak perfor- mance of 5.9 petaflops, which equates to almost six quadrillion (10¹⁵) arithmetic operations per second.

For our research, this means that we are now able to perform more complex simulations and can look for- ward to even more precise and informative results.

One of the projects that will benefit from the new pos- sibilities opened up by JUQUEEN is the simulation of the human brain. This is the objective of the Human Brain Project, on which we are working in cooperation with international partners and which has just been provided with generous funding by the EU as one of its flagships. However, research on novel materials and quantum physics, as well as energy and climate research will also profit from the improved computing power. In addition, JUQUEEN is also among the most energy-efficient supercomputers in the world.

In this issue of Research in Jülich, we are pleased to introduce you to this ‘Queen of Computers’. Fur- ther topics include merging stars, a new type of bat- tery based on silicon and air, and the decision- making behaviour of managers.

Be prepared to be surprised by our research!

I hope that this issue makes for interesting reading.

Yours sincerely, Prof. Achim Bachem

Chairman of the Board of Directors of Forschungszentrum Jülich

:: EDITORIAL

The neurons in the brain exchange information via a gigantic network of connections known as synapses.

To date it was unclear how and when these relay stations form and disappear. Neuroscientists from the Bernstein Center Freiburg and the Institute of Neuroscience and Medicine at Forschungszentrum Jülich recently presented a new ex- planation in the journal PLOS Com-

putational Biology. Using theoreti- cal models, they discovered a pre- viously unknown mechanism. If two neurons are already connected by several links, they form an addi- tional connection when exchanging information. However, this new synapse only continues to exists if the two neurons are active in the right order. Otherwise it will begin

to atrophy. ::

Cultivating Contacts in the Brain

Information in the brain is relayed from synapse to synapse.

High-energy photons (green arrow) release electrons from inside the sample (red arrow). Measuring these electrons provides information on the magnetic properties of the sample.

‘Hot’ Spins for Efficient Storage

Spin currents excited by laser pulses (red arrows) can increase the magnetization of layers.

Like Honey on Toast

T

hread-like molecules, such as DNA, form spirals when they flow through microscopically small channels.

Jülich scientists have provided explana- tions for the forces that bring about this deformation in the journal Physical Re- view Letters. Understanding the flow be- haviour of such molecules is important for the development of (disposable) medi- cal tests, for example, where tiny amounts of blood or other fluids flow through microscopic channels.

The researchers had simulated the movement of the chain-like molecules through a tube with a varying diameter.

Whereas the thread molecules were elongated while traversing the narrow segments, they curled when the tube be- came wider and eventually formed a spi- ral. The reason is the lower velocity of flow in the wider segments of the tube.

When they reach these segments, the

‘leading’ part of the molecule chain slows down while the rest follows at un- abated speed, causing the chain to roll

Thread-like molecules also form spirals when they flow.

up in the process. The shape of the emerging coil depends on several factors, including the flexi- bility of the long-chain molecules, their flow velocity, and the ratio of the different tube diameters.

A similar phenomenon of curling can also be observed in daily life: when hon- ey flows from the spoon onto your

breakfast toast. ::

An international team of researchers including scientists from Forschungs- zentrum Jülich have discovered a new physical effect in a system of magnet- ic layers. This effect, in which ‘hot’

spin currents are produced, could open up new avenues for computer technology. The magnetic properties of materials are based on electron spins.

In the future, these spins will be increasingly used to magnetically store information. The new effect could be utilized for a new generation of ultrafast, energy-efficient, high-

capacity computer storage. The re- searchers found that short laser puls- es are not only able to reduce the magnetization of layer, but also to in- crease it. Which of the two effects will occur depends on whether the orientation of the superimposed mag- netic layers was initially parallel or an- tiparallel. The laser pulses make ‘hot’

spins move extremely fast, thus caus- ing spin currents. The researchers are now searching for materials that in- duce stronger spin currents and for possibilities of selectively channelling these spin currents.

J

UQUEEN can outperform more than 90,000 PCs and is faster than its predecessor, the supercomputer JUGENE. But Forschungszentrum Jülich did not need to make any adjustments to the electricity supply or the contract with its energy provider when changing from the supercomputer JUGENE to JUQUEEN. The new computer with a Blue Gene/Q system from IBM actually con- sumes on average less power than its

predecessor – even though its comput- ing power is about six times as great.

One reason for this efficiency is JUQUEEN’s 458,752 processor cores.

Each of them is slower than the cores found in modern PCs. JUQUEEN’s devel- opers opted for these cores because with decreasing clock speed, the power consumption of each core decreases much more than the computing power.

The large number of cores means that

the overall JUQUEEN system is still ex- tremely fast. The important point is that the computer cores linking network and main memory all work in perfect har- mony.

“Another secret of JUQUEEN’s energy efficiency is the direct water cooling whereby, in contrast to its predecessor JUGENE, the cooling water removes the heat directly from the computer cores,”

explains Dr. Thomas Fieseler from the

A Queen to be Reckoned With!

JUQUEEN has taken up residence at Jülich. This is where Europe’s queen of computers meets with outstanding scientists who make good use of her talents in their research.

She joins an organization that provides support with computer simulations for scien-

tists from all over Europe and also experts already working on the energy-efficient

high-performance computers of the future.

Jülich Supercomputing Centre (JSC). The cooling water has to be demineralized to ensure that there is no damage to the fine water pipes supplying the computer chips. Jülich’s technicians have therefore constructed a closed water loop that pumps 150,000 l of water per hour through the computer.

NO TIME TO LOSE

“The challenge was not so much the individual technical adaptations but rath- er the logistics and the very tight time schedule,” says Fieseler, head of Tech- nology at JSC. In addition to modifying the water cooling, the technicians laid 112 power connections for JUQUEEN as well as about 4,400 m of supply lines with a total weight of almost 8,000 kg.

They also had to reinforce the floor of the Jülich Supercomputing Centre. Every square metre of the normal raised floor

Jülich’s new supercomputer can be used by scientists from all over Eu- rope. Two thirds of the computing time is allocated by two supercom- puting collaborations. One is the Gauss Centre for Supercomputing (GCS), an alliance of the three na- tional supercomputing centres in Jülich, Garching and Stuttgart. The other is the Partnership for Ad- vanced Computing in Europe (PRACE). The remaining third of the computing time is reserved for scientists at Forschungszentrum Jülich and the Jülich Aachen Re- search Alliance (JARA).

Who’s allowed computing time on JUQUEEN?

can bear a load of 500 kg. However, the cabinets housing JUQUEEN – referred to as racks by experts – with a floor space of 1.5 m² each weigh 2,100 kg.

“The schedule was drawn up with hardly any time margin to ensure that the changeover to JUQUEEN involved as little loss of computing time as possible,”

says Fieseler. After all, scientists from Forschungszentrum Jülich, from the Jülich Aachen Research Alliance, from Germany and all over Europe urgently require their allotted time on the computers at JSC (see also ‘Who’s allowed computing time on JUQUEEN?’). “The fact that we have applications from each of these levels which are assigned computing time on the basis of their scientific quality shows that this facility is in great demand,” says Dr. Norbert Attig, head of Application Support at JSC. If the supercomputers were to experience lengthy downtimes On the outside, Europe’s queen of computers is unspectacular

and overweight. Each of the 28 racks weighs in at 2,100 kg.

But inner values are what count.

then there would be a danger that scien- tists could not meet important project deadlines and would not be able to pub- lish their results as planned.

This is why the Jülich supercomputer experts operated JUGENE and the initial configuration of JUQUEEN in parallel for a time. IBM already supplied the first 8 out of a total of 28 racks in mid-April 2012. After they had been installed, JSC experts spent the next four weeks test- ing their function, performance and availability.

“Some of the tests we used we devel- oped ourselves,” explains Klaus Wolkers- dorfer, head of High-Performance Com- puting Systems. After passing the tests with flying colours the eight racks were officially put into operation. Since the re- searchers and their projects now had more computing time at their disposal than had been available on the whole of JUGENE the latter was finally shut down on 31 July 2012.

MORE COMPUTE NODES

One of the scientists who used the initial configuration of JUQUEEN is Dr.

Robert Jones. The physicist from Jülich’s Peter Grünberg Institute studies materi- als used for rewritable optical storage media such as DVD-RWs and Blu-ray discs and which are also of interest for future computer memories. Laser pulses can switch these phase-change materi- als back and forth between an ordered crystalline state and an unordered amor- phous state within a few billionths of a second.

By means of simulations based on theories of quantum mechanics, Jones and his colleagues have already made significant improvements to the under- standing of the processes taking place in two important families of phase- change materials. The software used by Jones has been adapted by IBM, with the scientist’s assistance, for use on JUQUEEN. In this way, the Jülich physi- At the moment SimLabs exist for

biology, plasma physics, particle physics, neuroscience, climate re- search, engineering, molecular physics and quantum chemistry.

SimLabs are groups of JSC staff who have a university degree in the respective subject and also have research experience in simu- lation methods and algorithms for supercomputers. Their main task is to help other scientists from their discipline make optimum use of the supercomputers.

Multidisciplinary assistance

A glimpse into JUQUEEN’s inner workings during installation.

cist was able to make effective use of a large number of compute nodes for his calculations soon after JUQUEEN had been put into operation. “We are thus able to include more atoms, simula te longer periods of time and also investi- gate several material systems simulta- neously,” Jones is happy to report. This means the results are more precise, in- formative and can be verified experi- mentally.

Jones is convinced that increasing knowledge about the processes at play in phase-change materials will help to improve data storage. The Australian- born researcher adds: “In the past 35 years I never had the feeling that com- peting scientists anywhere in the world have had an advantage over me and my colleagues. Here at Jülich we have al- ways had access to the latest generation of the best computers.”

JUQUEEN TOP OF THE CLASS

In November 2012 it became clear that JUQUEEN was at the top of its class when another 16 JUQUEEN racks went into operation, connected to the 8 origi- nal racks. In this second configuration stage JUQUEEN took place 5 in the TOP500 list of the fastest supercomput- ers in the world. This place on the list also confirmed that JUQUEEN was the first supercomputer in Europe able to perform more than five quadrillion arith- metic operations per second. The di- mension of this performance almost de- fies the human imagination. If JUQUEEN were to move one millimetre for each

arithmetic operation then in one second it would traverse the solar system – passing from the Sun to the dwarf planet Pluto.

At the beginning of this year, four fur- ther racks were added so that the JUQUEEN supercomputer reached its fi- nal maximum performance of 5.9 peta- flop/s (10¹⁵). For simulations to make good use of this facility they must be highly scalable, as the experts put it. The speed of the calculations should in- crease approximately in proportion to the number of computer cores employed without the necessary additional data traffic and the waiting for the required

Brain researcher Prof. Markus Diesmann (left) and materials scientist Dr. Robert Jones profit from JUQUEEN’s comput- ing capacity.

He didn’t just keep a firm grip on the cables but also on the tight instal- lation schedule for JUQUEEN:

Dr. Thomas Fieseler from JSC.

data becoming excessive. Simulations such as those performed by the group headed by Dr. Paul Gibbon from the Sim- ulation Laboratory (SimLab) Plasma Physics at JSC are highly scalable. The scientists are exploring the possibility of releasing particles from thin foils by means of high-power lasers. In this way, it may be possible to construct compact particle accelerators to be used in hospi- tals for radiotherapy, for instance.

If Gibbon had the whole JUQUEEN computer at his disposal for a time then without any statistical approximation he could simulate the more than 100 billion particles located in ten square micro- metres of these foils that are only one nanometre in thickness. “In this way, we would be able to implement a realistic numerical experiment for the first time by investigating the properties of the ion beam as a function of the thickness of the foil – as in a real laboratory experi- ment,” says Gibbon.

STORAGE SPACE FOR BRAIN MODEL The brain researchers headed by Prof. Markus Diesmann will also benefit from JUQUEEN. “We have already shown that our NEST software can exploit the parallelism of 100,000 compute nodes,”

says Diesmann. NEST is used to mathe- matically describe individual neurons in the human brain. The scientists enter da- ta on anatomy and electric properties and as a result they obtain a forecast of the activity in certain brain regions. Ulti- mately, the researchers hope to be able to better understand the principles ac- cording to which the brain operates.

“For our simulations it is, however, not only the enormous computing power of the JUQUEEN supercomputer that is im- portant but also its working memory, which has more space for data than its predecessor,” explains Diesmann. The researchers can now simulate larger re- gions of the brain than has previously been the case and thus also include in

A comparison of computer speeds He could efficiently use all JUQUEEN’s

458,762 processors for his research:

plasma physicist Dr. Paul Gibbon.

Royal progress

1

PC

speed

90,000 ^times

JUQUEEN

faster than a PC, 6 times faster than JUGENE

15,000

^times

JUGENE

faster than a PC

their model connections between neu- rons at great distances from each other.

“Experience teaches us that with a new supercomputer generation it is not only possible to produce better and more precise simulations but also that we suddenly come across surprising phenomena which only become observ- able with the size of the simulated com- plex system,” says Prof. Thomas Lippert, head of JSC. He conceived the idea of SimLabs so that scientists from a wide range of disciplines can effectively ex- ploit the potential of the Jülich super- computers. The idea is that a small team of highly qualified experts, who them- selves use supercomputers to perform research in their own disciplines, pro- vide support for other groups of scien- tists (see also ‘Multidisciplinary assis- tance’).

DEVELOPING FUTURE COMPUTERS However, the experts at JSC are not satisfied with merely operating the su- percomputers and providing user sup- port. Together with various commercial companies, they are involved in develop- ing the computers of the future (see also

‘Cooperations with companies’). By 2020, they intend to increase the perfor- mance of such computers by a factor of 200 in comparison to JUQUEEN – with- out any increase in energy consumption.

The quest for more energy efficiency is driven by economic and ecological mo- tives. Even today the costs of operating a supercomputer are in the same order as its purchase price. And German com- puter centres consume vast amounts of electricity equal to that generated by four medium-sized coal-fired power plants – with corresponding emissions of the greenhouse gas CO₂.

It is therefore not surprising that the topic of energy efficiency is high on JSC’s agenda. The staff at JSC have al- ready created software tools showing how much electricity is consumed by the individual components of supercomput- ers such as JUQUEEN during simula- tions. This is important for identifying

where future energy efficiency measures can be tweaked. One thing is already clear: “In this respect, the object is to further improve access to the working memory and mass memory as well as the input and output components,” says technology expert Thomas Fieseler. ::

Dr. Frank Frick

Prof. Thomas Lippert, head of the Jülich Supercomputing Centre, regards improving the supercomputers’ energy efficiency as a key task.

Cooperations with companies

At the Exascale Innovation Center, JSC works together with IBM on developing technologies for su- percomputers of coming genera- tions. At the same time, JSC is al- so concerned with future cluster computers – modular construc- tions of conventional PC compo- nents and fast networks. To this end, JSC operates the ExaCluster Laboratory with Intel and ParTec.

Finally, in collaboration with NVIDIA, JSC is investigating how graphics processing units can be used for the supercomputers of the future.

F

or some of us, the first decision must be taken in front of the ward- robe every morning: Which tie do I wear? Plain or patterned? This may be a gut decision or require some thought, depending on the appointments sched- uled for the day, or on the mood. Even the weather may play a role. Doctors, paramedics and managers, however, are required to take much more complex and serious decisions every day. It may be a matter of life or death, of saving or slashing jobs, of capital and livelihoods.

It is not just since the rise and fall of many an investment bank that econo- mists ask themselves: How do we make decisions?

THE BRAIN IN ACTION

A new branch of research – neuro- economics – is attempting to provide new answers. It combines questions from economics with findings from brain re- search. Jülich researcher Dr. Dr. Svenja Caspers is familiar with both worlds: she has degrees in business studies, in eco- nomics, and in medicine, and is therefore well acquainted with studies on de cision-

Whether they’re stockbrokers, chief executive officers or department heads, executives take decisions all day long. This apparently means that certain areas in their neuronal networks are more active than in those without managerial responsibilities.

This has been shown in a study by Dr. Dr. Svenja Caspers and her team from Forschungszentrum Jülich together with business psychologists and sociologists from the University of Cologne.

makers such as doctors and managers.

“Previous studies on those working in professions requiring immediate, intui- tive decisions based on certain rules and patterns were purely empirical

The first decision of the day: Which tie do I wear?

surveys,” says Svenja Caspers. She and her team wanted to know more and asked 35 executives from different sec- tors and a control group of non-manage- rial employees to make decisions. While the participants were working on this task, the researchers observed which areas of the brain were particularly active during the decision-making process by means of functional magnetic resonance imaging (fMRI).

DECISIONS WITHIN SECONDS

“The test subjects had to choose a concept from a word pair such as ‘team- work’ and ‘success’, ‘power’ and ‘loyal- ty’, or ‘diligence’ and ‘competence’ with- in two seconds,” says the researcher.

Altogether, they had to make 540 deci- sions within 22 minutes. The volunteers were asked to make a quick, spontane- ous decision on which word they pre- ferred – there were no wrong or right

answers. This appears to be an easy task, but it actually requires the brain to process a considerable quantity of information within a few milliseconds: symbols appear, and in a flash, the brain decides whether these are letters and if so, whether they form words. What’s the con- tent of these words and what do they mean to me? “The concepts then have to be weighed against each other and the participant must decide which of them they

Whether quick decisions are also good decisions is a question that was left unanswered in the study by Jülich researcher Dr. Dr. Svenja Caspers.

prefer,” says Svenja Caspers, describing the situation.

A well-trained neuronal network will tackle the task systematically: visual and acoustic information is processed in dif- ferent regions of the brain, the prefron- tal cortex receives signals from these regions, processes them, and relates them to existing knowledge. The so- called ‘caudate nucleus’ collects pat- terns of action from the past and auto- matically recalls them in similar situations. This helps to speed up the decision-making process, which is con- venient when someone is repeatedly confronted with the same type of deci- sion.

“In principle, the structure of the pathways is very similar in all individu- als,” says Svenja Caspers. “It’s not that in some of us, these networks are not used at all. However, the focus of the network, where most of the activity takes place, may shift.” For example, the current study revealed that in the brain of non-executives, the decision-making process was a successive one that in- volved many different areas of the brain.

In executives with managerial responsi- bilities, in contrast, the caudate nucleus was particularly active. At the same time, this group also took faster deci- sions. At the moment, the assumption that over the years, executives train themselves to make ‘fast-track’ deci- sions by falling back on their caudate nucleus is nothing but a hypothesis.

“This can only be investigated as part of a long-term study,” says Svenja Caspers,

and adds, “It also remains to be clarified whether such differences in the use of different brain areas can also be ob- served in more complex decision-making scenarios, for example in strategy devel-

opment processes.” ::

Brigitte Stahl-Busse

I

f you look into the sky at the constella- tion of Orion when the conditions are right, you will see the cluster of stars on which Christina Korntreff modelled her simulation. The Orion Nebula Cluster is one of the most productive stellar nurseries in relative proximity to the Sun.

Such clusters form from huge clouds of gas. In these clouds, gravity causes hydrogen molecules in particular to clump together until the atomic nuclei amalgamate and nuclear fusion is trig- gered. When this happens, a star is born.

“Over the last ten years, it has be- come clearer that stars are formed al- most exclusively in groups of stars re- ferred to as clusters,” explains Christina Korntreff. The 28-year-old is a PhD stu- dent at the Jülich Supercomputing Cen- Christina Korntreff doesn’t

need a telescope for her work. She researches stars by simulating them on supercomputers instead.

Merging Stars

When two stars become one: Christina Korntreff simulates the

interactions between gas and binary stars. Her work provides

insights into what happens when galactic molecular clouds

turn into fields of lower density.

The Orion Nebula, seen here through the Hubble Space Telescope, is a dense system of gases and stars.

This multicoloured emission nebula is one of the most productive stellar nurseries in the Milky Way.

stars in clusters are binaries, while in fields – such as the one through which the Sun is travelling – this applies only to 50 % of the stars.

Like a piece in a jigsaw puzzle, this discrepancy corresponds to another one that’s the point of departure for Christi- na Korntreff’s research. “In clusters of stars, many binary stars orbit each other very closely. This is much less frequently the case in fields.” This means that some binaries disappear when clusters dis- perse in the course of time and become fields. But why is this so?

Two years ago, another astrophysicist named Steven Stahler proposed a theo- ry to explain this phenomenon. It postu- lates that the gas in the cluster restricts the orbit of stars until, after millions of years, they merge to form a larger celes- tial body. This would mean that binary stars are only an episode in the life of some stars, like the caterpillar in a but- terfly’s.

However, astronomical theories that describe a development are difficult to verify. These processes take far too long to observe – if they can be seen at all with a telescope. “It would be very con- venient if it were possible to put the Ori- on Nebula into a box and look at what happens in time lapse,” says Christina Korntreff.

And that’s – at least roughly speak- ing – what they do at JSC. In order to get to the bottom of the disappearing binary stars, she and her colleagues used the JUROPA supercomputer to simulate a cluster of stars with the physical dimen- sions of the Orion Nebula: 4,000 stars and a comparable distribution of mass- es, periods of orbit, and gases. Calculat- ing the gravitational forces as precisely as possible was a special challenge in this simulation. Gravitational equations including more than two bodies are tricky – like equations to determine the number pi, they can only be solved ap- proximately. Mathematicians refer to this as an n-body problem. “I was lucky to be able to fall back on an existing sim- ulation code. It describes particularly tre (JSC). She is the only astrophysicist

in the Computational Science group, which comprises researchers from very different disciplines.

What she finds fascinating about as- trophysics is that “we can learn anything at all about the stars when they’re so far away”. In fact, astronomical observa- tions provide nothing but snapshots – but theoretical astrophysicists like Christina Korntreff help us to get a bet- ter idea of what the universe looks like by interpreting these data.

BINARY STARS DISAPPEAR

For example, we know that approxi- mately 60 % of all stars are binary stars.

Some of them orbit each other in a few hours, others take thousands of years.

But what is striking is that about 75 % of

close binary stars separately, which pre- vents their internal interaction from slowing down the entire simulation,”

says the astrophysicist.

GAS ACTS AS HANDBRAKE

As part of the simulation of the clus- ter, she then calculated how, according to Stahler’s theory, gas and binary stars interact and the consequences of these interactions for the population of bina- ries in the cluster. “We were surprised how clearly our simulation reproduces the binary star populations in fields and clusters,” says Korntreff. This suggests that what happens in the star clusters is exactly what Stahler’s theory predicts:

The gravitational tug of the stars attracts gas, which becomes so dense that its force of attraction slows down the move- ment of the star – like a handbrake that is on slightly. This causes the orbit to be- come smaller and smaller. Within a peri- od of a million years, binary stars that initially circled one another at a distance of a hundred times that between the Sun and the Earth approach each other and begin to exchange matter – a bit like what happens in an umbilical cord – until they finally merge.

“Thanks to this simulation, we now have a better understanding of how bi- nary stars disappear and what happens when a cluster forms,” says the astro- physicist, on the significance of her find- ings for science. Her work with super- computers benefited from the exchange of know-how with colleagues at JSC. Her PhD supervisor was also at hand to offer expert advice – Prof. Susanne Pfalzner from the Max Planck Institute for Radio Astronomy (MPIfR) in Bonn. Together with her and another colleague from MPIfR, Christina Korntreff recently pub- lished initial results in the journal Astron- omy and Astrophysics. ::

Christoph Mann

T

he German federal government is backing electric vehicles in an ef- fort to protect the climate. It envis- ages that the Germans will be driving one million electric cars by 2020 and six million only ten years later. Experts for energy systems analysis at the Institute of Energy and Climate Research worked with partners from science and industry on the NET-ELAN project, investigating the possible impact of this political tar- get on the electricity grid, the energy in- dustry and the climate.

According to them, the use of electric vehicles would lead to a reduction of al-

most 5 % in the consumption of mineral oil products in the entire transport sector by 2030. The result: the emission of the greenhouse gas CO₂ would be reduced by between five and eleven million tonnes in Germany. “This figure has such a wide range because the electricity used to charge the batteries of the elec- tric vehicles comes from wind energy and the amount of electricity it generates fluctuates depending on weather condi- tions,” explains Jochen Linßen, lead au- thor of the NET-ELAN final report.

The study also verifies that the mar- ket introduction of electric cars as

Six million electric cars are expected to be on the road in Germany in 2030. According to a comprehensive study performed by a team headed by Jülich scientist Jochen Linßen, this would not necessitate any expansion of the country’s system of generating electricity.

planned by the federal government is technically feasible. If the cars are re- charged at defined times, Germany will not have to construct any additional power plants or adapt the electricity grid.

ELECTRICITY FROM WIND ENERGY?

In another respect, however, the ca- pacity of the planned grid will not be suf- ficient. Excess electricity from wind en- ergy can only be transported in part to the conurbations and thus to the charg- ing stations for electric cars. The excess electricity comes from planned wind

Recharging After Midnight:

Study on Electromobility

farms both onshore and offshore in the North Sea and Baltic Sea. On windy days, they will produce more power than will be immediately required. However, on calm days, they will not be able to cover the demand.

The study presents a solution that would allow electric cars in 2030 to con- sume up to 60 % of the electricity re- quired to charge them from otherwise unused wind energy. In addition to ex- panding the grid to combat bottlenecks, the following strategy will help: electric cars should be recharged throughout the night between the hours of midnight and six in the morning. During this time, the grid is not used to capacity as the de- mand for electricity is low and the po- tential excess electricity from wind ener- gy is particularly high.

This strategy is also advantageous for owners of electric cars, as it increases the battery lifetime when the charging process occurs shortly before the next journey begins. “A win-win situation for grid operators and consumers,” says Jochen Linßen.

However, none of this changes the fact that batteries still age with each charge cycle. And this is where research- ers see the biggest hurdle for feeding

stored energy back into the grid, as it would mean using private electric cars as mobile decentralized temporary stor- age devices. As the vehicle owners would pay for this increased use of the battery with a reduction of up to 25 % in battery lifetime, grid operators would have to compensate them accordingly.

Electrical vehicles would only be a

“small part of a bigger solution for the increased integration of renewables”, conclude the scientists in their study.

Long periods with no wind, for example, could not be compensated by using en- ergy stored in electric-vehicle batteries.

“To improve the reliability of the energy supply, which is increasingly being fed by renewable sources, innovative sta- tionary energy storage systems are a must – and this is one priority of Jülich research activities,” says Prof. Dr.-Ing.

Harald Bolt, member of the Board of Di- rectors.

CONCLUSIVE SCENARIO

As part of the NET-ELAN project, the scientists had to predict many trends for the future. How much energy will electric cars need on average per kilo- metre travelled? What distance will the average vehicle user drive every day? At what times will the electric cars be re- charged? What sort of grid will provide electric cars with their energy? What power plants or facilities will produce the electricity required? “Studies al- ready exist on some of these aspects.

Our study is unique in that we devel- oped a consistent and conclusive sce-

nario of a future energy supply in order to investigate the grid integration of electric vehicles,” says Linßen.

For him, the project, which linked cars on the road to the electricity indus- try, was a dream job: although he has worked in Jülich on energy systems analysis for more than ten years, he is actually a qualified vehicle engineer. ::

Dr. Frank Frick

• TU Berlin, Institute for Land and Marine Transportation Systems (ILS), Department for Automotive Engineering (KFZ)

• TU Berlin, Electrical Engineering and Computer Science, Sustainable Electric Networks and Sources of Energy (SENSE)

• Centre of Solar Energy and Hydrogen Research Baden-Württemberg (ZSW)

• Ford Forschungszentrum Aachen GmbH

• Vattenfall Europe AG Innovation Management

Partners in the NET-ELAN project

Dr. Jochen Linßen from Forschungs- zentrum Jülich is an expert in energy systems analysis and the lead author of the final report on the NET-ELAN project.

Will it be possible to recharge six million electric cars in Germany with excess electricity from wind energy in 2030?

The NET-ELAN study has the answer.

I

f you are on the road with a digital camera, smart phone or tablet com- puter then you have almost certainly got a lithium battery or lithium-ion bat- tery with you. At the moment, these bat- teries are the state of the art if you want to store as much energy as possible in as little material as possible. However, research laboratories around the world have long been working on new batteries with even higher energy densities to

achieve a breakthrough for electric cars and stationary storage technologies for wind and solar energy.

A particularly promising candidate is the lithium-air battery which could theo- retically achieve 50 times the energy density of present lithium-ion batteries.

“The use of lithium does, however, in- volve certain difficulties. It reacts vio- lently with atmospheric humidity or wa- ter. Furthermore, the metal is in short

supply and would soon become more expensive if demand increases sharply,”

says Prof. Rüdiger Eichel from Jülich’s In- stitute of Energy and Climate Research (IEK). This is where he sees major advan- tages for an alternative. Scientists from the Israel Institute of Technology – Tech- nion – in Haifa have developed such an alternative, which they presented for the first time in 2008: the silicon-air battery.

Silicon is obtained from sand and re-

Silicon in sand and oxygen in the balloon:

Prof. Rüdiger Eichel uses these symbols to show that the raw materials for the new type of battery can be found almost anywhere.

Storing Energy

with Silicon and Air

A new type of battery can do without scarce raw materials while being

environmentally friendly and robust. Jülich scientists are working on exploiting

its great potential for high-performance energy storage.

Silicon anode

Cathode: porous carbon and catalyst Teflon layer

Oxygen O₂

O^2- O^2-

RTIL electrolyte

(room-temperature ionic liquid) Current flow e^-

Nickel mesh

Si⁴⁺

serves are practically inexhaustible. It forms the basis of present computer chips.

THE OXYGEN TRICK

Just like lithium-air batteries, the theoretically high energy density of sili- con-air batteries is due to a special fea- ture. The function is based on a reac- tion of oxygen, which is not contained in the battery but is taken up from the ambient air during the discharge pro- cess. Since the oxygen is not contained in the battery the mass is much lower than that of a conventional battery.

Eichel, head of the new subinstitute of Fundamental Electrochemistry at IEK, is working on the silicon-air battery which consists of nontoxic and environ- mentally compatible components. In his research, he cooperates with the bat- tery’s inventor, Prof. Yair Ein-Eli. Collab- oration across boundaries has long be- come the norm in science. It is, however, a surprise to hear where the Israeli and the German got to know each other. “We met in China,” says Eichel. The reason was a conference that both scientists were attending.

Since then Eichel and his team have been exploring the reactions inside the battery which prevent it from providing as much energy as expected theoreti- cally.

First of all, the scientists used spe- cial spectroscopic methods to investi- gate processes at the electrode where oxygen is reduced (see also ‘How the new battery works’). This electrode, the cathode, consists of porous carbon and a catalyst which accelerates the con- version of oxygen. So far, the German and Israeli scientists have been using manganese dioxide as a catalyst.

Eichel’s team have now discovered that some of this material reacts with the battery electrolyte. This has two un- desirable consequences. Firstly, the activity of the catalyst particles is re- duced. Secondly, they get bigger and thus probably increasingly clog the electrode pores so that less oxygen can pass through.

CATALYST UNDER OBSERVATION This is why the Jülich scientists are ex- perimenting with other catalysts. “The aim is to discover an optimum compro-

mise between very active but very expen- sive materials and less effective but cheaper catalysts,” explains Eichel. Ac- cording to Eichel, the search was indeed successful but the results have not yet been published. Eichel, who is a physicist, is pleased that they managed to observe the catalyst using spectroscopic methods at all. This is by no means self-evident since the catalyst is finely distributed in the form of tiny particles, some of which are deep inside the cathode pores.

In the meantime, the researchers have also made another very surprising discov- ery. “It used to be considered obvious that if the metal-air batteries did not yet function as desired then the cathode was the culprit,” says Eichel. But now the sci-

entists from Jülich and Haifa have discov- ered that this is not the case with the sili- con-air battery. They demonstrated that above all processes at the silicon anode currently inhibit the battery discharge.

This opens up a completely new approach for improving this innovative energy stor-

age technology. ::

Dr. Frank Frick

The battery is based on the oxidation of elementary silicon into the silicon- oxygen compound silicon dioxide. When the battery discharges, the metal- lic silicon is oxidized to silicon oxide. The resulting electrons flow through a power cable from the silicon anode (left) to a nickel mesh on the cathode (right). This is where molecular oxygen is reduced to oxygen ions. At the same time, silicon ions migrate through an ionic liquid and react with oxy- gen ions at the cathode to form silicon dioxide. The oxygen for this reaction comes from the ambient air. It passes through a mechanically stable Teflon membrane into the battery to the cathode. The cathode consists of porous carbon and a catalyst which accelerates the reactions taking place there.

The ionic liquid – an organic salt with a particularly low melting point – is decisive for the battery function. It dissolves the elementary silicon out of the anode and converts it into ions which then migrate to the cathode.

How the new

battery works

From Vessels to a Network

Dmitry A. Fedosov received a Sofja Kovalevskaja Award from the Alexander von Humboldt Foundation.

The mathematician is using the award of € 1.3 million to set up a working group to simulate the blood flow in healthy and cancerous tissue. This knowledge will specifically improve tumour therapy.

In order to simulate blood flow in one cublic millimetre of tissue, researchers have to take into consideration many millions of blood cells, of which about five million are red blood cells.

T

he move to Jülich marks a new chapter in Dmitry A. Fedosov’s ca- reer. The thirty-year-old mathema- tician, who studied in Novosibirsk and took his PhD in the USA, has been given an opportunity at the Institute of Com- plex Systems that few scientists of his age enjoy. Since September 2012 he has headed a working group and has a say in where their research is going.

ceivable that we could ever simulate the entire human microcirculation,” says Fe- dosov.

CANCER DRUGS

Nevertheless, the Russian scientist still considers it possible to reproduce the network of the blood flow. This would be a milestone in simulation and also the key to further knowledge. In Fedosov’s goal is to simulate the

micro circulation of blood in both healthy tissue and in tumours. The microcircula- tion is a network of ultrafine blood ves- sels such as capillaries, many times thin- ner than a single hair, that spread through body tissue. “If all the fine blood vessels in the human body were placed end to end they would pass around the Earth more than twice. It is hardly con-

concrete terms, this could help doctors to deal more effectively with a wide- spread problem in cancer treatment.

“Many drugs have only a limited effect.

The blood that transports the drugs flows in a different way in tumours than in healthy tissue,” says the mathemati- cian. Medical scientists have studied cancerous tissue and discovered special properties of the blood vessels. How- ever, the treatment generally remains the same. “The dose is increased to in- crease the effect – but then the side ef- fects also become more severe.”

In order to develop more efficient and less damaging methods we need to know more. How does the structure of the vessels affect the behaviour of blood cells? How does the efficacy of the drugs change if certain nanoparti- cles are added?

Such questions can hardly be an- swered without a sophisticated model of the microcirculation. Fedosov is convinced that he can provide such a model. “We intend to simulate the blood flow in a cubic millimetre of tissue. That would represent great progress.” A cubic millimetre sounds tiny but its micro- circulation represents a gigantic world with a dazzling array of events.

A MADDING CROWD

Many millions of blood cells swim around in the blood plasma in one cubic millimetre of tissue. About five million blood cells release oxygen there, take up carbon dioxide and change their shape;

white blood cells pass through the walls of the blood vessels and pass over into the tissue as antibodies. The blood cells are in constant motion, they repel each other and form clumps; the flows be- come incessantly thinner, thicker, slower or faster. In short, there is a madding crowd of blood cells. The simulation of blood flows therefore represents a great challenge for fluid dynamics.

As one of only a few scientists world- wide, Dmitry A. Fedosov has risen to the challenge. In his award-winning PhD the- sis, he presented a method of simulating blood flows. “From existing knowledge, I develop a model, from which I form algo- rithms and translate these into software codes. I then check my model against data from experiments. Once the model is verified I expand it.”

He can thus push forward into fields which are inaccessible to experiments for ethical or technical reasons. In his PhD thesis, for example, he was able to predict how red blood cells behave in the case of malaria.

The results are one reason why the Humboldt Foundation awarded him one of the most valuable German science prizes, the Sofja Kovalevskaja Award.

This award is intended to attract top- class researchers to Germany. The mathematician will receive € 1.3 million over a period of five years to set up and direct his own working group.

GEOMETRY OF THE BLOOD VESSELS What Fedosov has now set his sights on goes far beyond his PhD thesis. He intends to raise the level of his modelling from the vessels to a network. This is more than a quantitative leap. He will not only have to simulate more blood

cells but also the complex geometry of the network of blood vessels and the flu- id dynamics of blood at branches in the network.

If he is to succeed the model must be as simple as possible. The trick is to rec- ognize what is indispensable for repre- senting the system and get rid of everything else. At Jülich, Fedosov is currently mainly concerned with techni- cal aspects. For example, he is distribut- ing the calculations between the proces- sors of the supercomputers so that as many as possible are in operation. At the moment, due to the complex geometry of the model a large number of proces- sors are idle. However, Fedosov is mak- ing rapid progress and he is sure that in spring he will be able to simulate a net- work with simple branches. That would be a great step forward. ::

Christoph Mann

Dmitry A. Fedosov has already lived in Siberia and the USA. At Jülich, the thirty-year-old mathe- matician heads a group working on the simulation of blood flow.

Information Pathways in the Brain

T

he individual regions of the brain can be represented in a way that resembles a map. The associated ‘data highways’ can be made visible with a technique using polarized light – the physical principles of this method have been known for some 150 years. Jülich researchers have re- fined this method, which they refer to as ‘polarized light imaging’, and are now using it to visualize pathways that transport information in the brain:

neuronal fibre tracts. This allows them to see the layout of these fibre tracts and which regions of the brain they connect with a resolution of just a few micrometres.

As material for their studies, the scientists use ultrathin slices of the brain – about 3,000 per organ. Each of these slices is examined bit by bit with polarized light. When the light hits a fibre tract, its properties undergo a measurable change. Using state-of-the-art signal and image processing techniques, the group of researchers headed by Markus Axer from the In- stitute of Neuroscience and Medicine (INM) link the information contained in each slice, thus reconstructing the three-dimensional layout of neuronal fibre tracts in the brain.

The maps depicting these fibre tracts add to the brain atlas that Jülich researchers have been working on for more than 15 years. It contains structural informa- tion and attributes functions to different areas of the brain. The fibre tract pathways are another piece in the jigsaw puzzle towards understanding the healthy brain, which is expected to help re- searchers diagnose diseases at an early stage and develop more specific treatments. ::

1

2

3 4

PUBLICATION DETAILS Research in Jülich Magazine of Forschungszentrum Jülich, ISSN 1433-7371 Published by:

Forschungszentrum Jülich GmbH

| 52425 Jülich Germany Concep- tion and editorial work: Annette Stettien, Dr. Barbara Schunk, Dr.

Anne Rother (responsible accord- ing to German press law) Authors:

Dr. Frank Frick, Christian Hohlfeld, Christoph Mann, Tobias Schlößer, Dr. Barbara Schunk, Brigitte Stahl- Busse, Angela Wenzik Translation:

Language Services, Forschungs- zentrum Jülich Graphics and lay- out: SeitenPlan GmbH, Corporate Publishing, Dortmund Images:

Forschungszentrum Jülich (2, 3 left and centre, 4 top left and top right, 5 bottom, 6–11, 13 centre, 14 left, 17, 18, 21), Amunts, Zilles, Axer et al./Forschungszentrum Jülich (3 right, 22–23), iStockphoto/

Thinkstock (20), NASA, STScI, ESA (14–15 background), Axel Pfaender (cover and 6–11 illustrations), PhotoHouse/Shutterstock.com (12–13 top), rangizzz/Shutter- stock.com (12 bottom), George Rudy/Shutterstock.com (5 top), Spectral-Design/Shutterstock.

com (4 bottom), Tesla Motors (16) Contact: Corporate Communica- tions | Tel: +49 2461 61-4661 | Fax: +49 2461 61-4666 | Email:

info@fz-juelich.de Neuronal fibre tracts in the brain

are made visible by means of po- larized light in histological frontal sections that are 70 μm thin:

1 Fibre tracts in the brain of a mouse (different colours repre- sent different pathways) 2 Fibre tracts in a human brain,

postprocessed image 3 Fibre tracts in the brain of a

mouse

4 Fibre tracts in the human visual cortex

5 Fibre tracts in a human brain, represented as 3D ‘tubes’

5

Member of: