ERC Stories

Fracture, a central problem of engineering

As a leading expert in statistical and theoretical physics from the National Research Council in Italy (CNR), Dr Zapperi is well placed to examine the dynamics of complex materials and the size effects in fracture and plasticity.

“I have always been fascinated by the way things break differently at different scales; this has been a central problem of engineering”, says Dr Zapperi. “The one atom-thick sheets of graphene that you use in laboratories and large pieces of architecture such as bridges.do not fail in the same way. Size effects are immensely complex phenomena and our goal is to understand how collective effects – i.e. the motion of atomic defects and cracks in materials– can impact their physical behaviour when the scale changes”.

An area where pragmatism is still king

There already exists a lot of empirical knowledge about fracture and plasticity. “Engineers for instance know well how to avoid that elevators fall, by making them much stronger than required. These issues are already part of their everyday work but a complete theory about fracture and plasticity of materials is not yet in sight”, notes Dr Zapperi.

In the ERC project, he plans to establish a universal law for failure statistics that could be applied to a large array of different materials, including metals, glass, crystalline materials, amorphous materials such as gels, etc.

Taking the example of water which boils under a certain quantity of heat that is proportional to its volume, Dr Zapperi explains that the theories of fracture and plasticity don’t follow the same proportionality principle. There is no simple way to estimate the load at which a large sample will break just by knowing the fracture load of a smaller sample. Referring to Leonardo da Vinci’s wires that are exhibited in the Milano Science Museum, he explains that on average, longer wires are more likely to possess weak parts and to fail at smaller loads. For instance a chain will break at its weakest link. To sum up, he says “the larger, the weaker - the smaller, the stronger”.

In contrast, the stress required to deform plastic materials (the so-called yield strength) does not depend very much on the size of the object. Micron-sized samples, however, are much stronger than bulk ones and are also less predictable in the way they deform.

By using a standard method called the “renormalization group” (RG), which allows the study of how the system behaves depending on its scale, the research team plans to better understand size effects in fracture and plasticity.

Dr Zapperi is convinced that his research is particularly relevant at times where we push devices to smaller and smaller scales. “Understanding size effects in micron-scale ductile materials like metals could be helpful to better control fluctuations in their deformation, which is important in manufacturing microelectronic components, for instance”.

Freedom of research

Regarding the ERC funding, Dr Zapperi comments: “A lot of our work deals with computational work. The ERC grant was a real career boost as it helped me to hire five team members and to buy a dedicated computer cluster to make our simulations, instead of using standard desktop computers which by definition are much slower.” In terms of collaboration, he concludes: “The ERC funding allows us to make cutting-edge research and for us to cooperate with peers in other countries like the US or Finland. I find it quite exceptional to benefit from such freedom without being obliged to squeeze my research by pre-set priorities”.

Statistical Materials Modeling Laboratory

Size Effects in Fracture and Plasticity

Audio interview of Stefano Zapperi (new)

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Listen to the interview on SoundCloud

"Most of the writing about new urban citizenship is based on the assumption that contact with 'others' necessarily translates into respect for difference. This needs to be nuanced: many everyday moments of contact between citizens may not actually represent encounters at all", explains Prof. Valentine.

With her team, she wants to identify what kind of encounters produce 'meaningful contact' that actually changes values and translates into a more general positive respect of others. To address this question, she focuses on 'micropublics', i.e. sites such as libraries and sport clubs, where people from diverse backgrounds are brought together and can learn new ways of relating to each other.

"The capacity to live with difference confronts all countries of the EU, but there are some distinctions to make", notes Prof. Valentine. She distinguishes two important categories: the countries which were former colonial powers (such as UK, the Netherlands, France and Spain) and post-communist states in Eastern Europe (such as Poland, Latvia and Czech Republic). For the former ones, the challenges of multiculturalism have been faced since the post-war period. In contrast, it is only since 1989 that the homogeneity of former communist states has been significantly unsettled by contact with 'others'.

From Leeds to Warsaw - From research to politics

Prof. Valentine's programme of research aims to collect empirical data in two cities which she believes are representative: Leeds (UK) and Warsaw (Poland). Her research team is using innovative tools to collect testimonials, such as audio-diaries – to capture informants' reflections on their everyday lived encounters with difference – and time-lines built on in-depth life history interviews.

Her approach includes spatial experimentation. "With the help of ergonomics experts, movements therapists and architects, we aim to identify the types of activity and characteristics of particular spaces where meaningful contact can be produced or facilitated", explains Prof. Valentine.

"I have opted for a multidisciplinary approach, combining expertise from different fields including geography, urban studies, planning and sociology", she adds. The outcomes of the project will also leave a legacy beyond academic research. "I already have a collaborative relationship with the UK Equality and Human Rights Commission and I also expect strong interest from Polish government bodies and NGOs who are developing equality legislation and support for minority groups for the first time following their accession to the EU ", says Prof. Valentine.

On her €2.1 million ERC Advanced grant, she adds: "The ERC funding has been hugely important in enabling me to develop an interdisciplinary team of researchers at different career stages to address the important societal challenge of how we might develop the capacity for difference. It has enabled to work with a range of non-academic stakeholders and communities in both the UK and Poland which I hope will help us to generate findings that make a difference from the local to the European scale."

Looking forward, she plans to organise a two-day international conference in May 2014 where her findings will be showcased to European academics and 'stakeholder' dissemination workshops. In parallel, public exhibitions will also be organised in London, Warsaw and Brussels over the course of the year.

Publications

• Valentine, G. and Sadgrove J (2012) Lived difference: the transmission of positive and negative attitudes towards others Environment and Planning A 44: 2049-2067.
• Piekut, A., Valentine, G, Rees, P and Kupiszewski, M. (2012) Multi dimensional diversity in two European cities: thinking beyond ethnicity Environment and Planning A 44(12):2988-3009 2012.
• Andersson, J., Sadgrove, J. and Valentine G. (2012) Consuming campus: geographies of encounter at a British university, Social & Cultural Geography 13(5):501-515.
• Valentine, G. (2013) Living with difference: Proximity and encounter in urban life. Geography 98 (1):4-9.
• Website

Follow @LIVEDIFFERENCE on Twitter

Massive efforts worldwide have been devoted to support research and the European Union has funded neuroscience research through several programmes. Since its creation in 2007, the European Research Council (ERC) has been supporting cutting-edge and innovative studies in neurosciences. More than 200 research projects have been funded for a total budget of over € 250 million. About 15% of the projects funded in life sciences have a strong neuroscience component. Many of these projects address research and public health challenges and explore emerging areas in neurosciences.

Questions addressed by some ERC projects deal for instance with memory and information coding in the brain, genesis and repair of the nervous system, empathy and emotion processes, cell and gene therapy for Parkinson's and Alzheimer's diseases, computation models for man-machine interaction or retinal degeneration and blindness.

Some ERC projects in Neuroscience

Unravelling the processes of knowledge acquisition

Knowledge has a central role in our society. To understand more about the acquisition of knowledge and the brain mechanisms underlying it, ERC Advanced grantee Professor Richard Morris (University of Edinburgh, UK) is determining the neurobiological basis of ‘schemas’ in collaboration with Professor Guillén Fernández (Radbound University, The Netherlands). Schemas are the cognitive frameworks that help to organise and interpret information around us. The researchers are conducting an interdisciplinary experimental analysis of the mechanisms of acquiring knowledge, with a focus on the rapid acquisition and assimilation of new information into existing neural schemas. The researchers test how this rapid learning depends upon two components; novelty and prior knowledge. The study integrates animal experimentation with studies on humans; combining methods ranging from optogenetics to cognitive testing. In the long-term, the project aims to contribute to newer, more effective learning strategies.

Principal Investigator: Prof. Richard Morris
Host Institution: University of Edinburgh, UK
ERC Project: The neurobiology of schemas: knowledge acquisition and consolidation (NEUROSCHEMA)
ERC Call: Advanced Grant 2010
ERC Funding: € 3 million for five years
Researchers’ webpage

In search of how our brain feels

Humans have the capacity to slip into the skins of other people, to vicariously experience their actions and emotions. At the Royal Netherlands Academy for Arts and Sciences, ERC Starting grantee Professor Christian Keysers seeks to understand the processes of empathy within our neurons. His project consists of two complementary analyses. Along with his team, he will first examine how the network of regions involved in action observation in the brain - the “vicarious motor network” - integrate information. Challenging traditional models of action observation, the study will focus on directions of information flow between the vicarious motor nodes. The second analysis explores emotions; how neurons in brain regions associated with empathy respond to witnessing and experiencing emotions. This study will benefit life sciences, particularly genetics, and will inspire better therapies for psychiatric disorders of empathy such as autism. For robotics, it will concretise a biological example of how brains process and predict actions of others as well as read their feelings.
Illustration ©Dimitri_K

Principal Investigator: Prof. Christian Keysers
Host Institution: Royal Netherlands Academy of Arts and Sciences (KNAW)
ERC Project: Cracking the code and flow of empathy (VICARIOUSBRAIN)
ERC Call: Starting Grant 2012
ERC Funding: € 1.7 million for five years
Researcher’s webpage

Towards repair and regeneration of nerves after injury

Based at the University of Zurich (Switzerland), ERC Advanced grantee Professor Martin Schwab aims to better understand nerve-regeneration and functional recovery after injury to the body’s central nervous system (CNS). For these processes of repair, the inactivation of the membrane protein Nogo-A has been increasingly recognised. Along with his team, the researcher has found a member of a specific family of receptor proteins, to bind with high affinity Nogo-A, facilitating nerve fibre growth and plasticity. In particular, the group of Prof. Schwab plans to further understand the functional receptor complex that mediate Nogo-A signalling cascade and its regulatory role for synaptic plasticity and nerve fiber regeneration. The results will contribute to improve molecular and physiological understanding of Nogo-A, as well as strengthen the rationale for extending the indication of clinical anti-Nogo-A therapies from spinal cord injury to stroke.

Principal Investigator: Prof. Martin Schwab
Host Institution: University of Zurich, Switzerland
ERC Project: The Nogo-A receptor complex after CNS injury and its role in the developing and adult nervous system (NOGORISE)
ERC Call: Advanced Grant 2011
ERC Funding: € 2.5 million for five years
Researcher’s webpage

Cell therapy for treating blindness

Retinal degeneration, leading to the loss of photoreceptors, the light sensing cells of the retina required for vision, is a major cause of untreatable blindness. Seeking to develop stem cell therapy for such diseases, ERC Advanced grantee Professor Robin Ali conducts research at University College London (UK). He will determine whether embryonic stem (ES) cells can be used to repair degenerate retina and to model photoreceptor disorders. The project plans to establish new protocols for differentiating mouse and human ES cells into photoreceptors and to transplant these into degenerate retinas to test their ability to restore vision. The study also aims to use induced pluripotent stem cell technology to generate photoreceptors from patients with retinal disorders in order to study disease processes that might be corrected using drugs or other innovative technologies such as gene therapy.
Illustration © Robin Ali

Principal Investigator: Prof. Robin Ali
Host Institution: University College London, UK
ERC Project: Generation of stem cell derived photoreceptors for the treatment and modeling of retinal degeneration (STEMRD)
ERC Call: Advanced Grant 2012
ERC Funding: € 2.4 million for five years
Researcher’s webpage

Novel ways to address female health concerns

Addressing women’s health issues are of crucial importance. Based at the University of Milan (Italy), ERC Advanced grantee Professor Adriana Maggi examines the ways the liver uses information from hormones to integrate the metabolic, reproductive and hormonal status of women. She seeks to understand how the liver works in tandem with reproductive organs to regulate metabolism in response to reproductive needs and stages. The research proposes that the estrogen hormonal receptor ‘ER’ in the liver is a sensor of the body’s metabolic state; with consequences for female reproductive functions. To demonstrate this, the study will identify molecular pathways by which endocrine and nutritional inputs are recognised and integrated by the ER in the liver and discover the ways in which it aligns energy metabolism to meet requirements of the reproductive functions. The project will lead to better understanding female metabolic and reproductive disorders, particularly those related to menopause and ovarian malfunction, thereby resulting in the design of novel and more effective treatments.
Illustration © Adrianna Maggi

Principal Investigator: Prof. Adriana Maggi
Host Institution: University of Milan, Italy
ERC Project: Role of Liver Estrogen Receptor in female Energy Metabolism, Reproduction and Aging: What About Your Liver Sexual Functions? (WAYS)
ERC Call: Advanced Grant 2012
ERC Funding: € 1.4 million for five years
Researcher’s webpage

Computers need a power supply to process information, for example when typing a document or surfing the web. The same goes for the operations performed by our brain cells. With his BRAINPOWER project, Prof. David Attwell is setting out to understand how and where the energy supply of the brain is controlled. “The brain is powered by the glucose and oxygen which are provided to it in the blood. Because nerve cells use lots of energy, when they are active they signal to nearby blood vessels, telling the vessels to dilate, in order to deliver more substrates for energy production. These are the mechanisms we are studying.”

Failure of the energy supply to central nervous system tissue contributes to a wide range of neurological disorders such as stroke and spinal cord injury. These conditions have important social, economic and healthcare impact, as they are associated with increased disability and a larger risk of mortality, and they are rising in incidence in our increasingly ageing society.

It was long believed that cerebral blood flow is controlled by the large arterioles penetrating the brain from its surface. A few years ago, Prof. Attwell and his team discovered an alternative vascular mechanism that might control the brain’s blood flow, mediated by a specific type of contractile cell called ‘pericytes’.The team believes that these pericytes, situated on small capillary vessels, may play a crucial role in regulating the energy to brain nerve cells. “This hypothesis was controversial at that time but it is increasingly being accepted by the scientific community,” Prof. Attwell says. “Building on this initial discovery, there is now evidence that may help to explain some of the nerve cell damage that occurs after a stroke. When a blood clot occludes a cerebral artery, nerve cells are damaged, but even if the clot is removed with medicines a long-lasting decrease of blood flow remains, and this can damage more nerve cells. This may be caused by an abnormal constriction of pericytes triggered by the initial stroke."

The research team uses an advanced imaging methodology to understand how these intriguing cells function. With a two-photon microscope, researchers can study pericytes in brain slices as well as in anaesthetized rats and mice, and determine what dilates or constricts them. To mimic cerebrovascular diseases such as stroke, the team is using brain slices superfused with reduced oxygen and glucose concentrations, as well as anaesthetised animals with experimentally reduced blood flow (in collaboration with the groups of Martin Lauritzen in Copenhagen and Alastair Buchan in Oxford). “This approach has allowed us to suggest that capillaries dilate before arterioles when nerve cells are active in normal conditions, and we are investigating whether pericytes constrict in response to stroke and then die, leaving the capillaries permanently occluded”, notes Prof. Attwell.

Understanding how pericytes behave may also lead to the development of new pharmacological treatments to prevent pericyte death, which could help improve the number of nerve cells surviving after a stroke. A (currently hypothetical) medicine could be injected at the same time as the blood clots are removed, and would help patients to recover a normal blood flow to their brain. Prof. Attwell says: “Cerebrovascular conditions are currently very hard to treat, so this research gives the promising perspective that we may be able, in the long-term, to save lives”.

“The ERC funding not only cuts down on paperwork compared to usual schemes, but it has also been crucial for my work as it has allowed me to employ talented researchers in my team ”, declares Prof. Attwell. “It has also provided us with the necessary equipment, i.e. the 2-photon microscope, which allows us to see deeper into brain slices and into the living brain than is possible with a normal microscope, and hence to advance our research in neuroscience”.

Publications

• Attwell, D., Buchan, A.M., Charpak, S., Lauritzen, M., Macvicar, B.A. & Newman, E.A. (2010) Glial and neuronal control of brain blood flow. Nature 468, 232-243
• Harris, J.J. & Attwell, D. (2012) The energetics of central nervous system white matter. J. Neurosci. 32, 356-371.
• Hall, C.N., Klein-Flügge, M.C., Howarth, C. & Attwell, D. (2012) Oxidative phosphorylation, not glycolysis, powers presynaptic and postsynaptic mechanisms underlying brain information processing. J. Neurosci. 32, 8940-8951.

Imagine half a million Earths packed into a sphere 20 kilometers in diameter, spinning faster than an industrial kitchen blender. These extreme conditions, almost unimaginable by human standards, are met in neutron stars – a type of stellar remnant formed in the aftermath of a supernova explosion – which offer the opportunity to test physics under unique conditions. Neutron stars were first discovered around 50 years ago as pulsars which emit radio pulses like a lighthouse.

The pulsar in orbit, known as PSR J0348+0432 and its white-dwarf were recently discovered with the Green-Bank radio telescope. Separated by just 830,000 km, the pulsar and the white dwarf in this system are close enough to emit a significant amount of gravitational waves. According to the theory of general relativity, this close distance should make the orbital size and period shrink but to verify it, both the mass of the pulsar and its companion must be known.

“I was observing the system with the European Southern Observatory’s Very Large Telescope in Chile, and I was trying to detect changes in the light emitted from the white dwarf caused by its two million km/h motion around the pulsar. These changes of light allow us to weigh both the white dwarf and the pulsar”, says John Antoniadis, a member of the research team at MPIfR and the leading author of the paper. “After a quick analysis, I realized that the pulsar was a kind of heavyweight: a mass twice that of the Sun, making it the most massive neutron star we know about.”

With these masses, it is possible to calculate the amount of energy taken away from the system by gravitational waves, causing the orbital period to shrink. The team realized that this change in the orbital period should be visible in the radio signals of the pulsar and they focused on PSR J0348+0432, using the three largest single-dish radio telescopes on Earth (Green Bank, Arecibo and Effelsberg).

“Our radio observations with the Effelsberg and Arecibo telescopes were so precise that, by the end of 2012, we could already measure a change of 8 microseconds per year in the orbital period, exactly what Einstein’s theory had predicted”, states ERC grantee Paulo Freire from MPIfR. “The funding of the European Research Council is a truly momentous occasion for young researchers to conduct their research and acquire the equipment they need. My ERC grant will help us to develop a new state-of-the-art instrument for the Effelsberg radio telescope. With this new cutting-edge instrumentation, we expect to improve further the accuracy of today’s results.”

In terms of gravity, PSR J0348+0432 is a truly extreme object, even compared to the other pulsars used in the high-precision tests of Einstein’s general relativity. For instance, at its surface, the pulsar has a gravitational strength that is more than 300 billion times stronger than that on Earth. In its center, more than one billion tons of matter is squeezed into a volume of a sugar cube. These numbers nearly double the ones found in other ‘pulsar gravity labs’.

Despite these extreme conditions, the research team finds that the theory of general relativity still holds true.

The findings are also important for scientists who search for gravitational waves emitted by a collision between two neutron stars. These new measurements give them added confidence in the equations that describe the emission of gravitational waves during these mergers. These equations are the result of decades of mathematical research in general relativity and will be required to identify the first gravitational waves, which the team expects to happen within the next five years.