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News from the Department of Physics.

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    Professor Jeremy Baumberg

    Three Cambridge scientists are among those honoured by the Royal Society this week.

    Professor Jeremy Baumberg FRS, Department of Physics, received the Rumford Medal “for his outstanding creativity in nanophotonics, investigating many ingenious nanostructures, both artificial and natural to support novel plasmonic phenomena relevant to Raman spectroscopy, solar cell performance and meta-materials applications.”

    The medal is awarded biennially for important discoveries in the field of thermal or optical properties of matter and their applications.

    Professor Clare Grey FRS, Department of Chemistry, was awarded the 2014 Davy Medal for further pioneering applications of solid state nuclear magnetic resonance to materials of relevance to energy and the environment.

    This medal is awarded annually “for an outstandingly important recent discovery in any branch of chemistry”.

    In the lecture prizes Professor Nicholas Davies FRS, Department of Zoology, was awarded the Croonian Lecture for his work on the co-evolved responses of brood parasitic cuckoos and their hosts, the process of co-evolution and adaptation and the biology of the birds.


     

    The Royal Society has announced the recipients of its awards, medals and prizes for 2104.

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    A new method which uses tightly confined light trapped between gold mirrors a billionth of a metre apart to watch molecules ‘dancing’ in real time could help researchers uncover many of the cell processes that are essential to all life, and how small changes to these processes can lead to diseases such as cancer or Alzheimer’s.

    Researchers from the University of Cambridge have demonstrated how to use light to view individual molecules bending and flexing as they move through a model cell membrane, in order to better understand the inner workings of cells. Details are published today (12 August) in the journal Scientific Reports.

    The membrane is vital to the normal functioning of cells; keeping viruses out but allowing select molecules, such as drugs, to get through. This critical front line of cellular defence is made up of a layer of fatty lipids, just a few nanometres (one billionth of a metre) thick.

    When the cell membrane is damaged however, unwanted invaders can march into the cell. Many degenerative diseases, such as Alzheimer’s, Parkinson’s, cystic fibrosis and muscular dystrophy are believed to originate from damage to the cell membrane.

    The ability to watch how individual lipid molecules interact with their environment can help researchers understand not only how these and other diseases behave at their earliest stages, but also many of the fundamental biological processes which are key to all life.

    In order to view the behaviour of the cell membrane at the level of individual molecules, the Cambridge team, working with researchers from the University of Leeds, squeezed them into a tiny gap between  the mirrored gold facets of a nanoparticle sitting just above a flat gold surface.

    Through highly precise control of the geometry of the nanostructures, and using Raman spectroscopy, an ultra-sensitive molecular identification technique, the light can be trapped between the mirrors, allowing the researchers to ‘fingerprint’ individual molecules. “It’s like having an extremely powerful magnifying glass made out of gold,” said Professor Jeremy Baumberg of the NanoPhotonics Centre at Cambridge’s Cavendish Laboratory, who led the research.

    Analysing the colours of the light which is scattered by the mirrors allowed the different vibrations of each molecule to be seen within this intense optical field. “Probing such delicate biological samples with light allows us to watch these dancing molecules for hours without changing or destroying them,” said co-author Felix Benz. The molecules stand shoulder to shoulder like trees in a forest, while a few jitter around sideways.

    By continuously observing the scattered light, individual molecules are seen moving in and out of the tiny gaps between the mirrors. Carefully analysis of the signatures from different parts of each molecule allowed any changes in the molecule shape to be observed, which helps to understand how their reaction sites can be uncovered when they are at work. Most excitingly the team says these flexing and bending motions are not expected to occur at the slow time scales of the experiment, allowing the researchers  to make videos of their progress.

    “It is completely astonishing to watch the molecules change shape in real time,” said Richard Taylor, lead author of the paper.

    The new insights from this work suggest ways to unveil processes which are essential to all life and understand how small changes to these processes can cause disease.

    The research was funded by the UK Engineering and Physical Sciences Research Council and the European Research Council.

    A new technique which traps light at the nanoscale to enable real-time monitoring of individual molecules bending and flexing may aid in our understanding of how changes within a cell can lead to diseases such as cancer.

    It’s like having an extremely powerful magnifying glass made out of gold
    Jeremy Baumberg
    Lipid flexing within gap plasmon hot stop

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    The third annual Winton Symposium will be held on 29th September at the University’s Cavendish Laboratory. The topic for this year is ‘Global Challenges for Science and Technology’ and will again bring together leading scientists from around the world to explore how to tackle the increasing demands of a growing population with declining natural resources.

    Attendance is free of charge; however participants are required to register online due to the high demand for places.

    This year’s sessions for the one-day symposium will be:

    Session I
    The opening speaker is Professor Joseph Heremans from Ohio State University, who will discuss ‘Solid State Heat Engines and Waste Heat Recovery,’ providing insight into the design and use of thermoelectric systems for converting waste heat into useful energy. Professor Nina Fedoroff, who has performed pioneering work in the field of plant genetics and the development of modified crops, will speak on ‘Who will produce the food for a hotter, more crowded world?’ Fedoroff was Science and Technology Adviser to the US Secretary of State and director of the Center for Desert Agriculture at the King Abdullah University of Science and Technology and is currently the Evan Pugh Professor at Penn State University.

    Session II
    How can new technology make a difference on a global scale? Dr Simon Bransfield-Garth is CEO of Azuri Limited, a Cambridge company that provides affordable solar lighting in several parts of Africa, and will talk about ‘Empowering the Rural African Consumer.’ Professor Winston Soboyejo is at the Department of Mechanical and Aerospace Engineering at Princeton University and is President of the African University of Science and Technology. His talk ‘New Frontiers in Materials for Global Development: From Health to Energy and the Environment,’ will provide examples of applying mathematics to the development of novel materials including nanoparticles and bio-micro-electro-mechanical systems.

    Session III
    The focus of this session is on the provision of energy on a global scale, and the impact this has on people and the climate. Professor Richenda Van Leeuwen, Director of Energy and Climate at the United Nations Foundation, will address the growing needs for energy in her talk ‘Towards Sustainable Energy for All - innovation for energy access and development.’ She will draw upon her experience in providing energy services in the developing world and the impact on poverty alleviation. Professor David MacKay, Chief Scientific Advisor to the Department of Energy and Climate Change, and Regius Professor in Engineering at the University of Cambridge, will describe ‘The Global Calculator.’ He will discuss how this tool can be used to engage people in the debate on reducing international emissions and global action on climate change.

    “The increasing pressure that an ever-growing population is placing on our natural resources is one of the great challenges currently facing our world,” said Dr Nalin Patel, Programme Manager for the Winton Programme. “This year’s speakers are all addressing these challenges in unique and ground-breaking ways, and we are delighted to welcome them to Cambridge.”

    The symposium is organised by Dr Patel and Professor Sir Richard Friend, Cavendish Professor of Physics and Director of the Winton Programme for the Physics of Sustainability.

    For more information, please contact Dr Nalin Patel: nlp28@cam.ac.uk; 01223 760302

    On September 29th, the Department of Physics will host the third annual Winton Symposium at the Cavendish Laboratory on the theme of ‘Global Challenges for Science and Technology’.

    The increasing pressure that an ever-growing population is placing on our natural resources is one of the great challenges currently facing our world
    Nalin Patel
    Global challenges for science and technology

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    The researchers, from the Cavendish Laboratory and the Department of Chemistry, are devising new methods for understanding the complex interactions that take place within lithium-ion batteries, in order to identify and develop the best materials to make better batteries.

    Using software to predict the characteristics of materials before they’re synthesised in order to guide and interpret experiments, the researchers successfully predicted the structures of a series of lithium silicides, an important step in understanding batteries made of silicon, and have also predicted new structures for a battery based on germanium. Details are published in the journal Physical Review B.

    The lithium-ion battery market is large and growing rapidly. However, for many next-generation applications, such as longer-range electric vehicles and longer-lived consumer electronics, batteries which are smaller, more efficient and charge faster are needed.

    Silicon has been proposed as a replacement for carbon in battery anodes, or positive electrodes, for the past 20 years. The anode must safely store lithium atoms when charged then release lithium ions, in turn causing electrons, which carry electrical current, to flow from the positive to the negative electrode. The more lithium the anode can store, the larger its capacity.

    Most modern anodes are based on graphite, but silicon has roughly ten times the storage capacity, which in turn would greatly expand the capacity of the batteries used in mobile phones, electric vehicles and other applications. However, difficulty in managing silicon’s properties has prevented the technology from being applied at scale.

    “It’s always exciting when we’re able to successfully predict something, but it’s especially gratifying to predict something that’s really useful,” said Dr Andrew Morris of the University’s Cavendish Laboratory, the paper’s lead author.

    Lithium ion batteries are widely used due to their high energy density and high specific energy. They have a higher capacity than any other type of commercially-available battery, but in order to enable next-generation electronic devices, materials which can absorb, store and then release lithium quickly and safely need to be found.

    More efficient batteries could potentially revolutionise a number of industries: for instance, enabling an electric car battery to be recharged in the same amount of time it currently takes to fill up a petrol tank, or allowing the energy generated by renewables to be stored for when it is most needed.

    The various structures which the researchers predicted for lithium silicide have been shown to be stable in physical experiments, and further experiments are currently underway in Professor Clare Grey’s laboratory in the Department of Chemistry to determine whether the same is true for the structures they predicted for germanium and to determine the roles these structures play on battery cycling.

    The arrangement of atoms in a material determines its properties – what it looks like, how hard or soft it is, or what electrical state has. Performing simulations in a computer is far more efficient than making new materials in a laboratory and performing physical experiments on them. “What happens in a battery is complicated, and we need to work out what the model compounds should be,” said Morris.

    To perform their predictions, the researches used a method called AIRSS (Ab Initio Random Structure Searching), developed by one of the authors, Professor Chris Pickard of University College London, and Professor Richard Needs of the University’s Cavendish Laboratory. Starting with a random collection of atoms, AIRSS is able to predict the crystal structure of the materials they will form using only quantum mechanics.

    The research was funded by the Winton Programme for the Physics of Sustainability and the Engineering and Physical Sciences Research Council (EPSRC).

    Researchers from the University of Cambridge have devised a new simulation technique which reliably predicts the structure and behaviour of different materials, in order to accelerate the development of next-generation batteries for a wide range of applications.

    What happens in a battery is complicated, and we need to work out what the model compounds should be
    Andrew Morris
    Low-energy Li1Si1 phases

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    Newly-developed synthetic membranes provide a greener and more energy-efficient method of separating gases, and can remove carbon dioxide and other greenhouse gases from the atmosphere, potentially reducing the cost of capturing carbon dioxide significantly.

    The synthetic membranes, made of materials known as polymers of intrinsic microporosity (PIMs), mimic the hourglass-shaped protein channels found in biological membranes in cells. The tiny openings in these molecular ‘sieves’ – just a few billionths of a metre in size – can be adjusted so that only certain molecules can pass through. Details are published in the journal Nature Communications.

    Current methods for separating gases are complex, expensive and energy-intensive. Additionally, conventional polymers, while reliable and inexpensive, are not suitable for large scale applications, as there is a trade-off between low permeability levels and a high degree of selective molecular separation.

    Researchers are attempting to develop new methods of energy-efficient and environmental-friendly membrane-separation technology, which is an essential process in everything from water purification to controlling gas emissions.

    The team from the University’s Cavendish Laboratory, working with researchers from Kyoto University, has developed an alternative approach to generating polymer membranes, ‘baking’ them in the presence of oxygen, a process known as thermal oxidation.

    Inducing a thermal oxidation reaction in the PIMs causes the loosely-packed long chains of polymer molecules to form into a cross-linked network structure, with hourglass-shaped cavities throughout. This structure not only results in a membrane which is more selective to gas molecules, but also the size of necks and cavities can be tuned according to what temperature the PIMs are ‘baked’ at.

    “The secret is that we introduce stronger forces between polymer chains,” said Dr Qilei Song of the Cavendish Laboratory, the paper’s lead author. “Heating microporous polymers using low levels of oxygen produces a tougher and far more selective membrane which is still relatively flexible, with a gas permeability that is 100 to 1,000 times higher than conventional polymer membranes.”

    The cross-linked structure also makes these membranes more stable than conventional solution-processed PIMs, which have a twisted and rigid structure - like dried pasta - that makes them unable to pack efficiently. Thermal oxidation and crosslinking reinforces the strength of channels while controlling the size of the openings leading into the cavities, which allows for higher selectivity.

    The new membrane is twice as selective for separation carbon dioxide as conventional polymer membranes, but allows carbon dioxide to pass through it a few hundred times faster. These thermally modified PIMs membranes are among molecular sieves with the highest combinations of gas permeability and selectivity. In addition to possible uses for separating carbon dioxide from flue gas emitted from coal-fired power plants, the membranes could also be used in air separation, natural gas processing, hydrogen gas production, or could help make more efficient combustion of fossil fuels and power generation with much lower emissions of air pollutants.

    “Basically, we developed a method for making a polymer that can truly contribute to a sustainable environment,” said Professor Easan Sivaniah from Kyoto University's Institute for Integrated Cell-Material Sciences (iCeMS).

    “This new way of modifying PIMs brings the prospect of large-scale, energy-efficient gas separation a step closer,” said Professor Peter Budd, from the University of Manchester, one of the inventors of PIMs materials.

    This research was supported by the Engineering and Physical Sciences Research Council (EPSRC) and the European Research Council (ERC).

    Researchers from the University of Cambridge have developed advanced molecular ‘sieves’ which could be used to filter carbon dioxide and other greenhouse gases from the atmosphere.

    Heating microporous polymers using low levels of oxygen produces a tougher and far more selective membrane which is still relatively flexible
    Qilei Song
    Polymer molecular sieves with interconnected pores (in green) for rapid and selective transport of molecules

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    School physics students and their teachers can now tackle an interactive library of problems designed to develop their physics and maths problem-solving skills, thanks to isaacphysics.org, the latest strand of  the Rutherford School Physics Partnership.

    An open online course, isaacphysics.org challenges participants to solve a series of physics and maths problems, each tailored to the individual’s skills and experience. Questions are supported by hints and tips from Cambridge physics staff and undergraduates. Isaac is a bespoke tool for teachers and their students as they transition from GCSE (Y11) through to Sixth Form (Y12 & 13) and on to university.

    Registered students will be able to record their performance, save their question gameboards, and develop a personal portfolio of completed boards tailored to their progress.

    Registered participants will be able to watch lectures from the University’s Cavendish Laboratory, to participate in group problem-solving sessions in a Google+ hangout and, as the site develops, collaborate in teams to solve problems together.

    The overall goal of the Rutherford School Physics Partnership is to show students what STEM at top universities is about and to make it more accessible to all, by supporting students as individual learners. Isaac introduces students to the different style of study they will need at university, engaging them in the intellectual challenge of university physics, maths and engineering.

    “We want Isaac Physics to be particularly useful for students in schools that struggle to deliver specialist maths and physics teaching,” explains Professor Mark Warner, Co-Director of the Rutherford School Physics Partnership.

    “Isaac Physics can be used as a stand-alone learning resource by students who want to improve their physics and maths skills, or by teachers looking to improve fluency and depth of understanding in their students.

    “As the site develops, teachers will be able to set questions from the website for a whole class, and Isaac will mark the work and provide feedback to teachers and students.”

    “Working in groups and analysing problems posed in words alone, through diagram sketching and the application of fundamental concepts, are skills that students need to develop in order to do well at university-level physics.  In addition, students also need to learn how to cope when they don’t get the answer right first, or even second, time.”

    said Dr Lisa Jardine-Wright, Co-Director of the Rutherford School Physics Project.

    “These questions will require thought, but are achievable, and students will gain in confidence and the questions will become easier with practice.  Students shouldn’t be put off if they need to use the hints to reach the answer.

    “Even as professional physics researchers, we can find ourselves struggling to solve a problem, and getting it wrong at first. The challenge, and the satisfaction, comes from persevering, working the problem out, and getting it right in the end.”

     

    New online resource will help schools and pupils build specialist maths and physics skills.

    We want Isaac Physics to be particularly useful for students in schools that struggle to deliver specialist maths and physics teaching.
    Professor Mark Warner, Co-Director of the Rutherford School Physics Partnership
    More information:
    • The site can be found at: https://isaacphysics.org/
    • Around 80,000 students take AS and A2 physics. Around 100,000 achieve A*-B in GCSE physics and have the potential to go on to AS physics.
    • isaacphysics.org, and the Rutherford Schools Physics Partnership, aims to smooth the transition between these stages and to encourage students to continue studying physics, maths and engineeringat more advanced levels, by developing student skills and confidence.
    • For students: Questions have associated concept sheets, graded hints and hint videos. There are challenge questions, and themed sets of questions. If students register, then their progress will be followed, levels and problems will be suggested to them, they will be contacted about events open to them and about new materials being made available.
    • For teachers: in the next phase of the project, registered teachers will be able to follow the progress of students in their school, suggest selected problem sets to them and have them marked by Isaac, with results returned automatically.

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    The awards are part of a £125 million investment by the BBSRC announced today by Business Secretary Vince Cable. Mr Cable said: “The UK punches far beyond its weight in science and innovation globally, which is a credit to our talented scientists and first-class universities.

    “This new funding will safeguard Britain’s status as a world leader in life sciences and agricultural technology.”

    The funding has been awarded to leading universities and scientific institutions across the UK through Doctoral Training Partnerships that provide skills and training for bioscience PhD students. The strategic investment will ensure that researchers are trained in areas that will benefit the UK and will help to develop new industries, products and services.

    Dr Celia Caulcott, BBSRC Executive Director, Innovation and Skills: “Bioscience is having a massive impact on many aspects of our lives.  BBSRC is paving the way for an explosion in new economic sectors and bioscience that will change the way we live our lives in the twenty-first century. To achieve this we need to maintain our leading position in global bioscience by ensuring that the next generation of scientists have the best training and skills.”

    The funding to Cambridge will facilitate a number of doctoral training places across the University in the School of the Biological Sciences as well as Chemistry, Physics, Applied Mathematics & Theoretical Physics, Chemical Engineering & Biotechnology, and the Institute of Metabolic Science, as well as with partner institutes including the Wellcome Trust Sanger Institute and the Babraham Institute.

    Professor Graham Virgo, who takes up the post of Pro-Vice-Chancellor for Education at the University this month, says: “These Doctoral Training Partnerships will provide opportunities for exceptional students to pursue their graduate studies at Cambridge in areas of bioscience that are vital to both our future society and economy. They will bring together departments from across the University and our partner institutes in a truly cross-disciplinary manner.”

    Excellent and highly skilled researchers are vital to fuelling discoveries and helping to solve some of the world's major challenges. By investing in the skills base BBSRC not only supports and develops research, but also helps to secure the nation's future, driving inward investment, creating new jobs and maintaining the UK's position as a global leader.

    The University of Cambridge is to receive £15 million over five years from the Biotechnology and Biological Sciences Research Council (BBSRC) to support the training and development of 150 PhD students. Students will be trained in world-class bioscience that will help boost the economy and build on UK strengths in areas such as agriculture, food, industrial biotechnology, bioenergy and health.

    These Doctoral Training Partnerships will provide opportunities for exceptional students to pursue their graduate studies at Cambridge in areas of bioscience that are vital to both our future society and economy.
    Graham Virgo
    Postdoctoral students

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    Researchers have developed a new method for harvesting the energy carried by particles known as ‘dark’ spin-triplet excitons with close to 100% efficiency, clearing the way for hybrid solar cells which could far surpass current efficiency limits.

    The team, from the University of Cambridge, have successfully harvested the energy of triplet excitons, an excited electron state whose energy in harvested in solar cells, and transferred it from organic to inorganic semiconductors. To date, this type of energy transfer had only been shown for spin-singlet excitons. The results are published in the journal Nature Materials.

    In the natural world, excitons are a key part of photosynthesis: light photons are absorbed by pigments and generate excitons, which then carry the associated energy throughout the plant. The same process is at work in a solar cell.

    In conventional semiconductors such as silicon, when one photon is absorbed it leads to the formation of one free electron that can be extracted as current. However, in pentacene, a type of organic semiconductor, the absorption of a photon leads to the formation of two electrons. But these electrons are not free and they are difficult to pin down, as they are bound up within ‘dark’ triplet exciton states.

    Excitons come in two ‘flavours’: spin-singlet and spin-triplet. Spin-singlet excitons are ‘bright’ and their energy is relatively straightforward to harvest in solar cells. Triplet-spin excitons, in contrast, are ‘dark’, and the way in which the electrons spin makes it difficult to harvest the energy they carry.

    “The key to making a better solar cell is to be able to extract the electrons from these dark triplet excitons,” said Maxim Tabachnyk, a Gates Cambridge Scholar at the University’s Cavendish Laboratory, and the paper’s lead author. “If we can combine materials like pentacene with conventional semiconductors like silicon, it would allow us to break through the fundamental ceiling on the efficiency of solar cells.”

    Using state-of-art femtosecond laser spectroscopy techniques, the team discovered that triplet excitons could be transferred directly into inorganic semiconductors, with a transfer efficiency of more than 95%. Once transferred to the inorganic material, the electrons from the triplets can be easily extracted.

    “Combining the advantages of organic semiconductors, which are low cost and easily processable, with highly efficient inorganic semiconductors, could enable us to further push the efficiency of inorganic solar cells, like those made of silicon,” said Dr Akshay Rao, who lead the team behind the work.

    The team is now investigating how the discovered energy transfer of spin-triplet excitons can be extended to other organic/inorganic systems and are developing a cheap organic coating that could be used to boost the power conversion efficiency of silicon solar cells. 

    The work at Cambridge forms part of a broader initiative to harness high tech knowledge in the physical sciences to tackle global challenges such as climate change and renewable energy. This initiative is backed by the UK Engineering and Physical Sciences Research Council (EPSRC) and the Winton Programme for the Physics of Sustainability.

    A new method for transferring energy from organic to inorganic semiconductors could boost the efficiency of widely used inorganic solar cells.

    The key to making a better solar cell is to be able to extract the electrons from these dark triplet excitons
    Maxim Tabachnyk
    When light is absorbed in pentacene, the generated singlet excitons rapidly undergo fission into pairs of triplets that can be efficiently transfered onto inorganic nanocrystals.

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  • 10/10/14--06:55: Stem cell physical
  • One of the many mysteries surrounding stem cells is how the constantly regenerating cells in adults, such as those in skin, are able to achieve the delicate balance between self-renewal and differentiation – in other words, both maintaining their numbers and producing cells that are more specialised to replace those that are used up or damaged.

    “What all of us want to understand is how stem cells decide to make and maintain a body plan,” said Dr Kevin Chalut, a Cambridge physicist who moved his lab to the University’s Wellcome Trust-MRC Cambridge Stem Cell Institute two years ago. “How do they decide whether they’re going to differentiate or stay a stem cell in order to replenish tissue? We have discovered a lot about stem cells, but at this point nobody can tell you exactly how they maintain that balance.”

    To unravel this mystery, both Chalut and another physicist, Professor Ben Simons, are bringing a fresh perspective to the biologists’ work. Looking at problems through the lens of a physicist helps them untangle many of the complex datasets associated with stem cell research. It also, they say, makes them unafraid to ask questions that some biologists might consider ‘heretical’, such as whether a few simple rules describe stem cells. “As physicists, we’re very used to the idea that complex systems have emergent behaviour that may be described by simple rules,” explained Simons.

    What they have discovered is challenging some of the basic assumptions we have about stem cells.

    One of those assumptions is that once a stem cell has been ‘fated’ for differentiation, there’s no going back. “In fact, it appears that stem cells are much more adaptable than previously thought,” said Simons.
    By using fluorescent markers and live imaging to track a stem cell’s progression, Simons’ group has found that they can move backwards and forwards between states biased towards renewal and differentiation, depending on their physical position in the their host environment, known as the stem cell niche.

    For example, some have argued that mammals, from elephants to mice, require just a few hundred blood stem cells to maintain sufficient levels of blood in the body. “Which sounds crazy,” said Simons. “But if the self-renewal potential of cells may vary reversibly, the number of cells that retain stem cell potential may be much higher. Just because a certain cell may have a low chance of self-renewal today doesn’t mean that it will still be low tomorrow or next week!”

    Chalut’s group is also looking at the way in which stem cells interact with their environment, specifically at the role that their physical and mechanical properties might play in how they make their fate decisions. It’s a little-studied area, but one that could play a key role in understanding how stem cells work.
    “If you go to the grocery store to buy an avocado, you’re not going to perform lots of chemistry on it in order to decide which is the best one: you’re going to pick it up and squeeze it,” said Chalut. “In essence, this is what we’re trying to do with stem cells.”

    Chalut’s team is looking at the exact point where pluripotency – the ability to generate any other cell type in the body – arises in the embryo, and determining what role physical or mechanical signals play in generating this ‘ultimate’ stem cell state.

    Using fluid pressure to squeeze the stem cells through a channel, as well as miniature cantilevers to push down on the cells, the researchers were able to observe and measure the mechanical properties of these master cells.

    What they found is that the nuclei of embryonic stem cells display a bizarre and highly unusual property known as auxeticity. Most materials will contract when stretched. If you pull on an elastic band, the elastic will get thinner. If you squeeze a tennis ball, its circumference  will get larger. However, auxetic materials react differently – squeeze them and they contract, stretch them and they expand.

    “The nucleus of an embryonic stem cell is an auxetic sponge – it can open up and soak up material when it’s pulled on and expel all that material when it’s compressed,” said Chalut. “But once the cells have differentiated, this property goes away.”

    Auxeticity arises precisely at the point in a stem cell’s development that it needs to start differentiating, so it’s possible that the property exists so that the nucleus is able to allow entrance and space to the molecules required for differentiation.

    “There’s a lot of discussion about what exactly it means to be pluripotent, and how pluripotency is regulated,” said Chalut. “Many different factors play a role, but we believe one of those factors may be a mechanical signal. This may also be the case in the developing embryo.”

    By bringing together physics and biology, Simons and Chalut believe not only that some of the defining questions in embryonic and adult stem cell biology can be addressed, but also that new insights can be found into mechanisms of dysregulation in disease, cancer and ageing.

    “One of the reasons that this bringing together of disciplines sometimes doesn’t work so well is that physicists don’t want to understand the biology and biologists don’t want to understand the physics,” said Chalut. “In a sense, biologists don’t know the physical questions to ask, and physicists don’t know the biological questions to ask. As a physicist, the main reason I wanted to move my lab to the Stem Cell Institute is I thought there was no point working in biology if I didn’t understand which questions to ask.”

    “There’s a real effort being made to combine biology and physics much more than they have been in the past,” added Simons. “It takes a bit of a leap of faith to believe physics will enrich the field of biology, but I think it’s a very reasonable leap of faith. Scientific history is full of fields that have been enriched by people coming in and looking at an issue from different directions.”

    Inset image: Kevin Chalut (left) and Ben Simons.

    Looking at stem cells through physicists’ eyes is challenging some of our basic assumptions about the body’s master cells.

    What all of us want to understand is how stem cells decide to make and maintain a body plan
    Kevin Chalut
    Stem cells show auxeticity; the nucleus expands, rather than thins, when it's stretched

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    Work has begun on a centrepiece building created to pioneer revolutionary “blue skies” research and industrial partnership in the physical sciences.

    The start of construction on the £26 million Maxwell Centre marks a crucial early stage of a major move into new facilities for the staff of the Cavendish Laboratory.

    Once completed in 2015 the building will offer laboratory and meeting spaces for more than 230 people.

    The new facilities will see research scientists from industry occupying laboratory and desk space alongside the Cambridge research groups, with the aim of creating a two-way flow of ideas and exposing the best early career researchers to scientific problem-solving that relates directly to industrial need.

    “This building will affect how we work together and promote the free-flow of ideas, providing the right sort of meeting places for people to generate innovative research,” said Professor Sir Richard Friend, Cavendish Professor of Physics, who will be the first Director of the Centre.

    “The Maxwell Centre design means it is a building that brings in other departments such as Chemistry and Material Sciences.”

    “It will also very much promote engagement with industry, large and small, showing that we recognise industry as a source of intellectual innovation.”

    The centre will build on the research activity currently supported by the Winton Programme for the Physics of Sustainability at Cambridge’s Cavendish Laboratory, where the focus has been on original, risk-taking science since its inception in March 2011, emphasising fundamental physics research relevant to areas such as renewable energy.

    Pioneering research from the Winton programme, including the new physics of materials that could harness superconductivity to revolutionise battery life, will be able to flourish at the centre.

    Many other aspects of fundamental physics will be fostered, including advanced scientific computing, the theory of condensed matter, advanced materials and the physics of biology and medicine.

    The Centre is named to commemorate physicist James Clerk Maxwell, who was appointed the first Professor of Experimental Physics at Cambridge in 1871 and who discovered electromagnetism and founded statistical mechanics.

    Located between the Physics of Medicine building and the William Gates building on the West Cambridge site the Centre is due to open its doors in the summer of 2015.

    Among those present at the ceremony was Francis Shiner, Managing Director of SDC Builders Ltd, the construction contractor carrying out the work on behalf of the University.

    Funding for the project from the non-governmental sector was raised partly through philanthropic gifts and matched by industrial contracts with a very wide range of industries, including those collaborating with cognate departments such as Materials Science and Chemistry.

    The Higher Education Funding Council for England (HEFCE) is providing a significant contribution to complement the non-governmental sources of funding for the programme.

    Work begins on £26 million building named after physicist James Clerk Maxwell.

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    Researchers from the University of Cambridge have identified a class of low-cost, easily-processed semiconducting polymers which, despite their seemingly disorganised internal structure, can transport electrons as efficiently as expensive crystalline inorganic semiconductors.

    In this new polymer, about 70% of the electrons are free to travel, whereas in conventional polymers that number can be less than 50%. The materials approach intrinsic disorder-free limits, which would enable faster, more efficient flexible electronics and displays. The results are published today (5 November) in the journal Nature.

    For years, researchers have been searching for semiconducting polymers that can be solution processed and printed – which makes them much cheaper – but also retain well-defined electronic properties. These materials are used in printed electronic circuits, large-area solar cells and flexible LED displays.

    However, a major problem with these materials – especially after they go through a messy wet coating, fast-drying printing process – is that they have an internal structure more like a bowl of spaghetti than the beautifully ordered crystal lattice found in most electronic or optoelectronic devices.

    These nooks and crannies normally lead to poorer performance, as they make ideal places for the electrons which carry charge throughout the structure to become trapped and slowed down.

    Polymer molecules consist of at least one long backbone chain, with shorter chains at the sides. It is these side chains which make conjugated polymers easy to process, but they also increase the amount of disorder, leading to more trapped electrons and poorer performance.

    Now, the Cambridge researchers have discovered a class of conjugated polymers that are extremely tolerant to any form of disorder that is introduced by the side chains. “What is most surprising about these materials is that they appear amorphous, that is very disordered, at the microstructural level, while at the electronic level they allow electrons to move nearly as freely as in crystalline inorganic semiconductors,” said Mark Nikolka, a PhD student at the University’s Cavendish Laboratory and one of the lead authors of the study.

    Using a combination of electrical and optical measurements combined with molecular simulations, the team of researchers led by Professor Henning Sirringhaus were able to measure that, electronically, the materials are approaching disorder-free limits and that every molecular unit along the polymer chain is able to participate in the transport of charges.

    “These materials resemble tiny ribbons of graphene in which the electrons can zoom fast along the length of the polymer chain, although not yet as fast as in graphene,” said Dr Deepak Venkateshvaran, the paper’s other lead author. “What makes them better than graphene, however, is they are much easier to process, and therefore much cheaper.”

    The researchers plan to use these results to provide molecular design guidelines for a wider class of disorder-free conjugated polymers, which could open up a new range of flexible electronic applications. For example, these materials might be suitable for the electronics that will be needed to make the colour and video displays that are used in smartphones and tablets more lightweight, flexible and robust.

    This research was funded by the Engineering and Physical Sciences Research Council (EPSRC) and Innovate UK.

    A new class of low-cost polymer materials, which can carry electric charge with almost no losses despite their seemingly random structure, could lead to flexible electronics and displays which are faster and more efficient.

    What is most surprising about these materials is that they appear very disordered at the microstructural level, while at the electronic level they allow electrons to move nearly as freely as in crystalline inorganic semiconductors
    Mark Nikolka
    A high performance semiconducting polymer with an amorphous structure

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  • 11/28/14--01:45: Lighting up virtual worlds
  • By taking a branch of mathematics more often associated with astrophysics and applying it to computer gaming, Cambridge researchers have transformed how games are lit, and their spinout company Geomerics has now been acquired by ARM.

    Global games

    Set up in 2005 by Professor Mike Hobson, Dr Chris Doran and Professor Anthony Lasenby of the Cavendish Laboratory and Dr Joan Lasenby of the Engineering Department, Geomerics has transformed the way computer games are lit, helping games designers unleash their creativity and improving the gaming experience for millions of gamers worldwide.

    With its breakthrough product Enlighten, launched in 2007, Geomerics pioneered a new business sector in selling lighting middleware technology. And because it lights the virtual world in the same way the real world is lit, Enlighten underpins the world's most popular and biggest selling computer games.

    The first game using Enlighten was Battlefield 3. Since its release by Electronic Arts in 2011, Battlefield 3 has sold some 20 million copies, making it the fastest selling game in Electronic Arts' history. Battlefield 3 generated revenues of $1 billion and scooped more than 60 industry awards, including a BAFTA for best game in 2012.

    Licensed by more than 30 titles from the USA and Canada to Japan and Korea – via Iceland, Germany, Sweden, Norway, Russia and the Ukraine – Enlighten now has global reach. Geomerics became one of the first group of companies announced to be working on the PlayStation 4 with Sony, and in in 2013 Geomerics was acquired by ARM Holdings.
     

    Making it real

    Dwarfing the market in books and film, the global computer games market is worth $65 billion a year, with more than one billion people worldwide playing computer games. The UK is one of the industry's major players: Grand Theft Auto – developed by Edinburgh-based Rockstar – took $1 billion in the first 48 hours after its release.

    As the market grows in size and sophistication, developers and gamers want ever more realistic on-screen experiences, realism that depends, in large part, on lighting on-screen worlds in the same way the real world is lit. But achieving this using conventional mathematics – performing myriad calculations of how light bounces at 200 frames a second – proved impossible.

    So, at the Cavendish Laboratory, Hobson and Doran began exploring whether geometric algebra – a 'dialect' of mathematics more economical in its representation of geometrical objects – could solve the problem of real-time calculation of global illumination in a virtual world.


    Geometric algebra

    Between 1993 and 2005, the Astrophysics Group in the Department of Physics and the Department of Engineering's Signal Processing Group used new geometrical methods – including geometric algebra – in their research on theoretical physics, cosmology and astrophysics.

    Applied in electromagnetism as well as mechanics, relativity and quantum theory, geometric algebra allows the equations governing these physical phenomena to be written in a way that makes them easier to solve than traditional mathematics.

    From 2005, Doran used an EPRSC Advanced Fellowship to study how geometric algebra might be exploited in computer graphics. His research revealed that algorithms based on geometric algebra could solve problems in graphics and vision faster and better than traditional techniques.

    Based on years of research across several disciplines – from signal processing, compression and de-noising to surface mapping and spherical hemispheric lighting – Enlighten allows computer games to compute the bounced light in a world in real time for the first time.

    The latest Star Wars game and the new Mirror's Edge – they are all huge games and they are lit by our technology, and that's enormously exciting

    Professor Mike Hobson

    Enlighten has given us unparalleled productivity on Need for Speed: The Run

    Electronic Arts

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    The Funding will be provided by the Blavatnik Family Foundation.

    As a world-leading university, Cambridge seeks to bring together the most brilliant minds to freely interact, learn and discover. Its goal is to encourage and support the best people from around the world to work and study at the University. The new Blavatnik Fellowships offer an important addition in support of this aim.

    The Fellowship programme, which will run for an initial period of five years, will be administered by the British Council in Israel which actively promotes academic and scientific exchange between Israel and the United Kingdom, and is warmly supportive of the initiative.

    Fellows will receive an annual stipend of £30,000, and Fellowships will be tenable for up to two years.  It is planned that there will be at least three Fellows appointed each year, although it is anticipated that this number may increase in future years.

    The first three Fellows will research in the areas of Engineering, Genetics and Physics.

    Potential Fellows are encouraged to apply to the programme by the British Council. Successful applicants are selected by a committee of senior academics.

    Professor Eric Miska, the Herchel Smith Professor of Molecular Genetics and Senior Group Leader at the Gurdon Institute at the University of Cambridge said:

    “I am delighted to host a Blavatnik Fellow in my lab within the Gurdon Institute. Fellowships such as these enable the exchange of ideas and expertise that is the lifeblood of cutting-edge research. We’re deeply grateful to Leonard Blavatnik and the Blavatnik Family Foundation for their support and hope to host many more fellows in the future.”

    Mr Blavatnik, speaking on behalf of the Blavatnik Family Foundation, said: “I am very pleased to strengthen the Foundation’s existing links to Cambridge with this important initiative, which will serve the mutual interests of the University, the Israeli scientific community and those selected to be Blavatnik Fellows.”

    Professor Sir Leszek Borysiewicz, Vice-Chancellor of the University of Cambridge, said: “We are committed to enabling the very best people from around the world to come to Cambridge, to drive forward our pioneering research and address new questions. We are delighted that the generosity of Leonard Blavatnik and the Blavatnik Family Foundation adds a further way in which we can support this ambition.”

    A benefactor of the University of Cambridge, Leonard Blavatnik, has made a multi-million pound pledge to provide funding for Israeli scientists of outstanding ability to study in Cambridge.

    Fellowships such as these enable the exchange of ideas and expertise that is the lifeblood of cutting-edge research.
    Professor Eric Miska

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    A new study has successfully measured the coherence of electron spin – the period of time in which the particle’s elusive quantum state can be read and manipulated – for an electron trapped in conditions that could form the basis of a future quantum internet.

    The study, reported in the journal Physical Review Letters, was carried out by researchers at the Universities of Cambridge and Saarbrücken. It reveals the coherence time of an electron trapped in a silicon-based colour centre within a microscopic fragment of diamond. This is a gap, manufactured inside the diamond’s lattice structure, and designed to snare an electron so that it can be manipulated.

    At just 45 nanoseconds, the time period for which the electron’s spin is visible seems a miniscule fraction, but for scientists trying to bring this under control, it is, in relative terms, an age.

    The “spin” of a particle is its intrinsic angular momentum and can point either up or down. Physicists at numerous leading research universities, including Cambridge, are currently engaged in research which is trying to utilise spin to develop advanced quantum technologies.

    In the future, electron spin could be used to represent data and move large amounts of information much faster than is currently possible. This means that better control of spin might well underpin future computing, enable the creation of an entirely new quantum network (or quantum internet), and provide the foundations for a huge range of other technologies, such as advanced sensing devices.

    One problem that hinders scientists who are attempting to gain greater command over electron spin for this purpose, however, is that spins in solids cannot be seen, or manipulated, for very long. After a tiny fraction of a second has passed, the spin’s quantum state decays beyond the point of visibility. Therefore, it needs to be retained for long enough for information about the spin to be registered and manipulated.

    In the new study, the researchers successfully demonstrated the extent of the coherence of an electron trapped in a “silicon-vacancy” – an impurity in the lattice of carbon atoms that make up diamond. A silicon-vacancy centre provides highly promising conditions for the manipulation of electron spin.

    Building on previous research, the researchers put the electron into a “superposition” state, using a technique which involves targeting it with two lasers with carefully-tuned frequencies. In this quantum state, the spin of the electron is potentially both up and down, and it is useful because it provides a basic position from which they can then observe and measure changes using laser pulses. The vision for future spin-based technologies involves creating chains of electrons whose spin will change relative to one another based on this initial superposition concept.

    When applied to the electron in the silicon vacancy centre, the method achieved a coherence period of tens of nanoseconds – a fraction of time which, for scientists trying to control spin, is actually ample.

    Dr Mete Atature, a researcher at the Cavendish Laboratory and St John’s College, University of Cambridge, who led the study with Professor Christoph Becher in Saarbrcüken, said: “This is incremental research, but it essentially deals with the elephant in the room for these colour centres, which was whether there was long-living coherence for the electron spin or not, and whether we had time to see its quantum state?”

    “Arguably this is the most pressing challenge for these colour centres right now. We established that we can not only access the electron spin states, but also sustain an arbitrary superposition of them for 45 nanoseconds. When you bear in mind that it will take us picoseconds to execute laser-based operations to manipulate the spin, it becomes clear that just a fraction of this period is required. So this gives us a lot of possibilities to work with.”

    The vacancy centre was created by substituting a silicon atom and a gap in place of two neighbouring carbon atoms in the carbon lattice of a fragment of diamond. Research earlier this year showed that a silicon-based vacancy has the potential to be used for this purpose because the photons – or light particles – emitted by an electron trapped in such conditions are sufficiently bright, and on a sufficiently narrow bandwidth, to be attractive for various applications. The research adds to a growing realisation among scientists that silicon-vacancy centres could provide advantageous conditions for spin and photon control, simultaneously.

    “Now we know that silicon vacancies provide an alternative colour centre that has spin coherence, optical detectability and superior optical qualities,” Atature added. “The next challenge is to see if we can extend this spin coherence time by various techniques and, in parallel, see if we can entangle the spin with a single photon with sufficiently high fidelity.”

    In a breakthrough study scientists have revealed the coherence, or the visibility lifespan, of the spin of an electron in an emerging colour centre in diamond. This could provide a potential component for future quantum networks.

    We established that we can not only access the electron spin states, but also sustain an arbitrary superposition of them for 45 nanoseconds. When you bear in mind that it will take us picoseconds to execute laser-based operations to manipulate the spin, it becomes clear that just a fraction of this period is required.
    Mete Atature
    Atomic structure of the SiV- color center, consisting of an Si impurity (red) situated on an interstitial position along the bond axis and surrounded by a split-vacancy (transparent) and the next-neighbor carbon atoms (grey).

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    Researchers from the University of Cambridge have developed a new self-assembled material, which, by changing its shape, can amplify small variations in temperature and concentration of biomolecules, making them easier to detect. The material, which consists of synthetic spheres ‘glued’ together with short strands of DNA, could be used to underpin a new class of biosensors, or form the basis for new drug delivery systems.

    The interplay between the lipid spheres, called giant vesicles, and the strands of DNA produces a unique response when the material is exposed to changes in temperature. Instead of expanding when heated – as is normally the case – the material contracts, a phenomenon known as negative thermal expansion. Details are published today (7 January) in the journal Nature Communications.

    In addition to its role as a carrier of genetic information, DNA is also useful for building advanced materials. Short strands of DNA, dubbed ‘sticky ends’, can be customised so that they will only bind to specific complementary sequences. This flexibility allows researchers to use DNA to drive the self-assembly of materials into specific shapes.

    Basing self-assembled materials around vesicles – synthetic versions of the soft sacs which envelop living cells – allows for even more flexibility, since the vesicles are so easily deformable. Using short DNA tethers with a cholesterol ‘anchor’ at one end and an exposed sticky DNA sequence at the other, the vesicles can be stuck together. When assembled into a hybrid DNA-lipid network, the DNA tethers can diffuse and rearrange, resulting in massive vesicle shape changes.

    Besides negative thermal expansion, the researchers also found that changes in temperature lead to a significant variation in the porosity of the material, which is therefore highly controllable. A similar response is expected by changing the concentration of the DNA tethers, which could also be replaced by other types of ligand-receptor pairs, such as antibodies.

    “The characteristics of this material make it suitable for several different applications, ranging from filtration, to the encapsulation and triggered release of drugs, to biosensors,” said Dr Lorenzo Di Michele of the University’s Cavendish Laboratory, who led the research. “Having this kind of control over a material is like a ‘golden ticket’ of sensing.”

    This research is part of the CAPITALS, a UK-wide programme funded by the Engineering and Physical Sciences Research Council (EPSRC). Cambridge Enterprise, the University’s commercialisation arm, is currently looking for commercial partners to help develop this material.

    A new responsive material ‘glued’ together with short strands of DNA, and capable of translating thermal and chemical signals into visible physical changes, could underpin a new class of biosensors or drug delivery systems.

    Having this kind of control over a material is like a ‘golden ticket’ of sensing
    Lorenzo Di Michele
    A lipid membrane functionalised with DNA-linkers

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    Two teams of astronomers led by researchers at the University of Cambridge have looked back nearly 13 billion years, when the Universe was less than 10 percent its present age, to determine how quasars – extremely luminous objects powered by supermassive black holes with the mass of a billion suns – regulate the formation of stars and the build-up of the most massive galaxies.

    Using a combination of data gathered from powerful radio telescopes and supercomputer simulations, the teams found that a quasar spits out cold gas at speeds up to 2000 kilometres per second, and across distances of nearly 200,000 light years – much farther than has been observed before.

    How this cold gas - the raw material for star formation in galaxies - can be accelerated to such high speeds had remained a mystery. Detailed comparison of new observations and supercomputer simulations has only now allowed researchers to understand how this can happen: the gas is first heated to temperatures of tens of millions of degrees by the energy released by the supermassive black hole powering the quasar. This enormous build-up of pressure accelerates the hot gas and pushes it to the outskirts of the galaxy.

    The supercomputer simulations show that on its way out of the parent galaxy, there is just enough time for some of the hot gas to cool to temperatures low enough to be observable with radio telescopes. The results are presented in two separate papers published today (16 January) in the journals Monthly Notices of the Royal Astronomical Society and Astronomy & Astrophysics.

    Quasars are amongst the most luminous objects in the Universe, and the most distant quasars are so far away that they allow us to peer back billions of years in time. They are powered by supermassive black holes at the centre of galaxies, surrounded by a rapidly spinning disk-like region of gas. As the black hole pulls in matter from its surroundings, huge amounts of energy are released.

    “It is the first time that we have seen outflowing cold gas moving at these large speeds at such large distances from the supermassive black hole,” said Claudia Cicone, a PhD student at Cambridge’s Cavendish Laboratory and Kavli Institute for Cosmology, and lead author on the first of the two papers. “It is very difficult to have matter with temperatures this low move as fast as we observed.”

    Cicone’s observations allowed the second team of researchers specialising in supercomputer simulations to develop a detailed theoretical model of the outflowing gas around a bright quasar.

    “We found that while gas is launched out of the quasar at very high temperatures, there is enough time for some of it to cool through radiative cooling – similar to how the Earth cools down on a cloudless night,” said Tiago Costa, a PhD student at the Institute of Astronomy and the Kavli Institute for Cosmology, and lead author on the second paper. “The amazing thing is that in this distant galaxy in the young Universe the conditions are just right for enough of the fast moving hot gas to cool to the low temperatures that Claudia and her team have found.”

    Working at the IRAM Plateau De Bure interferometer in the French Alps, the researchers gathered data in the millimetre band, which allows observation of the emission from the cold gas which is the primary fuel for star formation and main ingredient of galaxies, but is almost invisible at other wavelengths.

    The research was supported by the UK Science and Technology Facilities Council (STFC), the Isaac Newton Trust and the European Research Council (ERC). The computer simulations were run using the Computer Cluster DARWIN, operated by the University of Cambridge High Performance Computing Service, as part of STFCs DiRAC supercomputer facility.

    Inset image: Comparison of observation and simulations. Credit: Tiago Costa

    Astronomers have been able to peer back to the young Universe to determine how quasars – powered by supermassive black holes with the mass of a billion suns – form and shape the evolution of galaxies.

    While gas is launched out of the quasar at very high temperatures, there is enough time for some of it to cool through radiative cooling – similar to how the Earth cools down on a cloudless night
    Tiago Costa
    Illustration of the outflow (red) and gas flowing in to the quasar in the centre (blue). The cold clumps shown in the inset image are expelled out of the galaxy in a 'galactic hailstorm'

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    The Funding will be provided by the Blavatnik Family Foundation.

    As a world-leading university, Cambridge seeks to bring together the most brilliant minds to freely interact, learn and discover. Its goal is to encourage and support the best people from around the world to work and study at the University. The new Blavatnik Fellowships offer an important addition in support of this aim.

    The Fellowship programme, which will run for an initial period of five years, will be administered by the British Council in Israel which actively promotes academic and scientific exchange between Israel and the United Kingdom, and is warmly supportive of the initiative.

    Fellows will receive an annual stipend of £30,000, and Fellowships will be tenable for up to two years.  It is planned that there will be at least three Fellows appointed each year, although it is anticipated that this number may increase in future years.

    The first three Fellows will research in the areas of Engineering, Genetics and Physics.

    Potential Fellows are encouraged to apply to the programme by the British Council. Successful applicants are selected by a committee of senior academics.

    Professor Eric Miska, the Herchel Smith Professor of Molecular Genetics and Senior Group Leader at the Gurdon Institute at the University of Cambridge said:

    “I am delighted to host a Blavatnik Fellow in my lab within the Gurdon Institute. Fellowships such as these enable the exchange of ideas and expertise that is the lifeblood of cutting-edge research. We’re deeply grateful to Leonard Blavatnik and the Blavatnik Family Foundation for their support and hope to host many more fellows in the future.”

    Mr Blavatnik, speaking on behalf of the Blavatnik Family Foundation, said: “I am very pleased to strengthen the Foundation’s existing links to Cambridge with this important initiative, which will serve the mutual interests of the University, the Israeli scientific community and those selected to be Blavatnik Fellows.”

    Professor Sir Leszek Borysiewicz, Vice-Chancellor of the University of Cambridge, said: “We are committed to enabling the very best people from around the world to come to Cambridge, to drive forward our pioneering research and address new questions. We are delighted that the generosity of Leonard Blavatnik and the Blavatnik Family Foundation adds a further way in which we can support this ambition.”

    A benefactor of the University of Cambridge, Leonard Blavatnik, has made a multi-million pound pledge to provide funding for Israeli scientists of outstanding ability to study in Cambridge.

    Fellowships such as these enable the exchange of ideas and expertise that is the lifeblood of cutting-edge research.
    Professor Eric Miska

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  • 02/16/15--04:33: Firing up the proton smasher
  • Large Hadron Collider

    While it slept, we were allowed into the tunnels.

    The Large Hadron Collider (LHC) had shut down for two years to upgrade following the discovery of the Higgs boson. In the main ring, 175 m underground, chunks had been cut out of the snaking tubes for essential maintenance. These tubes fire protons in opposite directions, whipping them ever faster until they almost reach the speed of light. Along the 27 km run are four ‘experiments’: vast machines envelop the points at which tubes intersect and particles collide to capture the results. The largest of these, ATLAS, is the size of a six-storey building.

    Each collision, known as an ‘event’, produces a splurge of elementary particles such as quarks, gluons and – as we now know – Higgs bosons. On average, events occur 40 million times a second in the LHC. 

    The precision required for these events is exquisite. Our guide tells us to imagine two people standing six miles apart and each simultaneously firing a gun so that the bullets meet exactly head-on. Except instead of bullets, imagine needles. Inside the tunnels, engineers zip past on bicycles – the best way to get around underground unless you’re a proton. Next to every lift shaft is a bike rack.

    In the next few months, the LHC will be switched back on. The 2012 triumph of demonstrating the Higgs boson affirmed the Standard Model: the elegant solution to the building blocks of the Universe. Now, with an anticipated almost doubling of energy for the LHC’s second run, physicists are aiming to “go beyond” the Standard Model.

    One of the central goals is to prove or disprove the theory of supersymmetry: the “prime candidate” theory for unlocking the mystery of the dark matter in our Universe.

    “Observable matter only makes up 5% of the Universe; the rest is what we call dark matter. We know it’s there because we can see galaxies rotating at velocities which require surrounding matter for such gravitational pull – but, unlike the part of the galaxies that we can see, we cannot detect it optically,” said Professor Val Gibson, Head of the Cambridge High Energy Physics (HEP) group.     

    Supersymmetry theory essentially predicts that every particle in the Standard Model has a matching particle waiting to be found. These partner particles (or ‘sparticles’) could be candidates for dark matter, but we haven’t yet seen them – perhaps because they are heavier and take more energy to generate, a problem LHC Run II could overcome.

    “Supersymmetry theory predicts there is a sister particle of the electron called a ‘selectron’, which would have integer ‘spin’: its intrinsic angular momentum. For the quark, there would be a supersymmetric ‘squark’, and so on for every elementary particle we know,” said Gibson. If supersymmetry is correct, there would also be a further four Higgs bosons for us to discover.

    “Proton collisions in the LHC might produce a heavy supersymmetric particle which decays into its lightest form, a light neutral particle, but different from those we know about in the Standard Model,” said Gibson.

    “We have been looking for supersymmetry particles throughout the first run of the LHC, and the increase in power for Run II means we can look at higher energies, higher mass, and gradually blot out more areas of the map in which supersymmetrical particles could be hiding.”

    Will supersymmetry be proved by the end of next year, or will the data show it’s a red herring? For HEP research associate Dr Jordi Garra Ticó, what is really fundamental is experimental evidence. “I just want to see what nature has prepared for us, whether that’s consistent with some current theory or whether it’s something else that no one has ever thought about yet, outside of current knowledge.”

    The two experiments that Cambridge researchers work on are the mighty ATLAS and the more subtle LHCb – known as LHC ‘Beauty’ – which is Gibson and Garra Ticó’s focus. Beauty complements the power of ATLAS, allowing scientists to ‘creep up’ on new physics by capturing rare particle decays that happen every 100 million events.

    Garra Ticó spent six months in Cambridge before taking up residence at CERN, where he works on LHCb. LHCb’s 10 million events a second create 35 kbyte of data each, a figure that is expected to go up to 60 kbyte during Run II – too much to ever imagine storing. “There is no guidebook,” he explained. “These machines are prototypes of themselves.”

    ATLAS, the biggest experiment, feels like the lair of a colossal hibernating robot. Engineers perch in the crevices of the giant machine, tinkering away like tiny cleaner birds removing parasites. And sealed in the heart of this monster is layer upon layer of the most intricate electronics ever devised.     

    Dr Dave Robinson arrived in CERN as a PhD student in 1985, and joined the Cambridge HEP group in 1993. He went back to CERN in 2004 – expecting a stint of “one to two years” – and has remained. He is now Project Leader for the most critical detector system within ATLAS, the Inner Detector, which includes the ‘semi-conductor tracker’ (SCT), partially built
    in Cambridge.

    Each collision event inside ATLAS leaves an impression on the layers of silicon that make up the SCT like an onion skin – enabling scientists to reconstruct the trajectory of particles in the events. “The sensitivity of the tracker is vital for making precise measurements of the thousands of particles generated by the head-on collisions between protons, including decay products from particles like b-quarks which only exist for picoseconds after the collision,” said Robinson.

    He is currently working with Gibson and colleagues at the Cavendish Laboratory on the next generation of radiation-proof silicon technology in preparation for the LHC shutdown of 2020, the next time they will be able to get at the SCT, which is otherwise permanently locked in the core of ATLAS. The technology will have an impact on areas like satellite telecommunications, where cheaper, radiation-hardened electronics could have a huge effect.

    This, for Gibson, is the way science works: solving technical problems to reveal nature’s hidden secrets, and then seeing the wider applications. She recalls being in CERN when she was a postdoc in the 1980s at the same time as Tim Berners-Lee, who was working on computer-sharing software to solve the anticipated data deluge from LHC-precursor UA1. He ended up calling it the World Wide Web.

    Inset image – top: representation of the Higgs Boson particle; Credit: CERN.

    Inset image – bottom: Professor Val Gibson.

     

    The Large Hadron Collider is being brought back to life, ready for Run II of the “world’s greatest physics experiment”. Cambridge physicists are among the army who keep it alive.

    I just want to see what nature has prepared for us, whether that’s consistent with some current theory or whether it’s something else that no one has ever thought about yet, outside of current knowledge
    Jordi Garra Ticó
    Large Hadron Collider

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    Yes

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  • 02/18/15--22:00: Illuminating art’s history
  • Faced with the prospect of his rapidly approaching nuptials on 29 October 1442, and with no wedding gift purchased for his bride-to-be, Francis I of Brittany (1414–1450) did what many of us have done at some point: he ‘re-gifted’. He took something that was already in his possession and gave it to someone else.

    But this was no ordinary gift: it was an illuminated manuscript, made for Francis’ first wife, Yolande of Anjou, who had died in 1440. Francis had it altered and presented it to his new bride, Isabella Stuart, daughter of James I. The portrait of his first wife was covered with that of Isabella and an image of St Catherine was added, using cheaper pigments. Then, when Francis was made a duke, the portrait was painted over yet again to give Isabella a coronet.

    Art historians have written volumes on the Hours of Isabella Stuart over the last century, but a cross-disciplinary Cambridge project is using a variety of imaging techniques to uncover this story of re-gifting. The team’s work is challenging previous assumptions about this and many other manuscripts, helping them to see and understand medieval painting and illumination in new and unexpected ways.

    Combining research in the arts, humanities, sciences and technology, MINIARE (Manuscript Illumination: Non-Invasive Analysis, Research and Expertise) currently focuses on uncovering the secrets of medieval art, but it is anticipated that many of the imaging techniques they are adapting may be used to study other types of art, from a range of different periods.

    The project is led by Dr Stella Panayotova, Keeper of Manuscripts and Printed Books at the Fitzwilliam Museum, and Professor Stephen Elliott of the Department of Chemistry, who are working with colleagues from across the University and around the world.

    “Working in a truly cross-disciplinary way can benefit art history, scientific research and visual culture in general, while pushing technology forward at the same time,” said Panayotova. “Thanks to the imaging techniques we’ve been using, we can see things in these manuscripts that we couldn’t see before.”

    Much of what we know about illuminated manuscripts comes from art-historical analysis and circumstantial evidence. Since they are so delicate and the layers of pigment are so thin, manuscripts are seriously compromised by taking samples, which is common practice for the analysis of panel or fresco paintings. To gather hard evidence about how these manuscripts were made, while preserving them, non-invasive techniques are required.

    “For our team, it was about finding new applications for existing techniques, and pushing them far beyond current boundaries in order to analyse the very thin layers of a manuscript,” said Elliott. “Part of our research is in the area of medical diagnostics and environmental sensing, where we analyse materials in very thin layers, which is not so different from analysing a painting. So we could certainly see what the problems were.”

    Using a combination of imaging techniques, including photomicroscopy, visible and infrared imaging at multiple wavelengths, reflectance imaging spectroscopy and optical coherence tomography, the MINIARE team is able to peer through the layers of a painting to uncover its history, as in the case of the Hours of Isabella Stuart.

    “We do have to adapt conventional analytical techniques to make them safe to use on something as fragile as an illuminated manuscript,” said conservation scientist Dr Paola Ricciardi. “For instance, Raman spectroscopy is a brilliant technique, but it’s a challenge to use it on a manuscript as we tend to use one-hundredth of the laser power that we would on a less fragile object.”

    The technological challenge for the MINIARE team is making sure the imaging technology is non-invasive enough to keep the manuscript safe, but still sensitive enough to get an accurate result. Many of the imaging tools that the team use are in fact not cameras, but scanners that acquire a spectrum at each point as they scan an entire object. The resulting ‘spectral image cubes’ can then provide information about the types of materials that were used, as well as the ability to see different layers present in the manuscript.

    Combining these non-invasive imaging techniques not only helps the researchers to distinguish between artists by analysing which materials they used and how they employed them, but also helps them to learn more about the technical know-how that these artists possessed.

    “Many of the artists we’re looking at didn’t just work on manuscripts,” said Panayotova. “Some of them were panel painters or fresco painters, while others also worked in glass, textiles or metal. Identifying the ways in which they used the same materials in different media, or transferred materials and techniques across media, offers a whole new way of looking at art.”

    For example, Ricciardi has found evidence for the use of smalt, a finely ground blue glass, as a pigment in an early 15th-century Venetian manuscript made in Murano. The use of a glass-based pigment is not unexpected given the proximity of the Murano glass factories, but this illuminator was working half a century before any other Venetian easel painter whose works are known to contain smalt.

    Another unexpected material that the MINIARE team has encountered is egg yolk, which was a common paint binder for panel paintings, but not recommended for manuscript illumination – instead, egg white or gum were normally used. By making a hyperspectral reflectance map of the manuscript, the researchers were able to gather information about the pigments and binders, and determine that some manuscript painters were most likely working across a variety of media.

    The techniques that the team are developing and refining for manuscripts will also see application in other types of art. “All of the imaging techniques we’re using on the small scale of medieval manuscripts need to be scalable, in order that we can apply them to easel paintings and many other types of art,” said Dr Spike Bucklow of the Hamilton Kerr Institute. “It’s an opportunity to see how disciplines relate to each other.”

    MINIARE (www.miniare.org) involves the Fitzwilliam Museum, Hamilton Kerr Institute, Departments of Chemistry, Physics, History of Art, History and Philosophy of Science, and Applied Mathematics and Theoretical Physics, as well as the Victoria & Albert Museum, Durham University, Nottingham Trent University, Antwerp University, Getty Conservation Institute, J Paul Getty Museum, National Gallery of Art in Washington DC and SmartDrive Ltd.

    Inset image – top: Macroscopic X-ray fluorescence imaging has allowed to prove the presence of smalt, a cobalt-containing glass pigment, mixed with ultramarine blue in selected areas of this early 15th century manuscript fragment painted by the Master of the Murano gradual; Left: Fitzwilliam Museum, Marlay Cutting It 18; Right: Cobalt distribution map; Credit: S. Legrand and K. Janssens, Department of Chemistry, University of Antwerp.

    Inset image – bottom: Hyperspectral reflectance imaging in the visible and near-infrared range confirms evidence for the use of egg yolk as a paint binder only in figurative areas within the decorated initials in the Missal of Cardinal Angelo Acciaiuoli, painted in Florence ca. 1404; Left: Fitzwilliam Museum, MS 30, fol 1r (detail); Centre: RGB composite obtained from the hyperspectral image cube; Right: egg yolk distribution map, showing its use to paint the figure of Christ with the exclusion of his ultramarine blue robe; Credit: J. K. Delaney and K. Dooley, National Gallery of Art, Washington DC.

    Scientific imaging techniques are uncovering secrets locked in medieval illuminated manuscripts – including those of a thrifty duke.

    Identifying the ways in which they used the same materials in different media, or transferred materials and techniques across media, offers a whole new way of looking at art
    Stella Panayotova
    Francis I of Brittany 'regifted' the Book of Hours to his second wife Isabella after having his first wife painted over

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    A prototype “green bus shelter” that could eventually generate enough electricity to light itself, has been built by a collaboration of University of Cambridge researchers and eco-companies.

    The ongoing living experiment, hosted by the Cambridge University Botanic Garden and open to the visiting public, is incorporated in a distinct wooden hub, designed by architects MCMM to resemble a structure like a bus shelter. Eight vertical green wall units – created by green wall specialists, Scotscape – are housed along with four semi-transparent solar panels and two flexible solar panels provided by Polysolar.

    The hub has specially adapted vertical green walls that harvest electrons naturally produced as a by-product of photosynthesis and metabolic activity, and convert them into electrical current. It is the brainchild of Professor Christopher Howe and Dr Paolo Bombelli of the Department of Biochemistry. Their previous experiments resulted in a device able to power a radio using the current generated by moss.

    The thin-film solar panels turn light into electricity by using mainly the blue and green radiation of the solar spectrum. Plants grow behind the solar glass, ‘sharing the light’ by utilising the red spectrum radiation needed for photosynthesis, while avoiding the scorching effect of UV light. The plants generate electrical currents as a consequence of photosynthesis and metabolic activity during the day and night.

    “Ideally you can have the solar panels generating during the day, and the biological system at night. To address the world’s energy needs, we need a portfolio of many different technologies, and it’s even better if these technologies can operate in synergy,” said Bombelli.

    The structure of the hub allows different combinations of the photovoltaic and biological systems to be tested. On the north east aspect of the hub, plants receive light directly, without being exposed to too much direct sun. On the south west orientation, a green wall panel is housed behind a semi-transparent solar panel so that the effect on the plants and their ability to generate current can be monitored. Next to that, in the same orientation, a single solar panel stands alone, and two further panels are also mounted on the roof.

    “The combination of horticulture with renewable energy production constitutes a powerful solution to food and resource shortages on an increasingly populated planet,” explained Joanna Slota-Newson from Polysolar. “We build our semi-transparent solar panels into greenhouses, producing electrical energy from the sun which can in turn be used to power irrigation pumps or artificial lighting, while offering a controlled environment to improve agricultural yields. In this collaboration with Cambridge University, the public can experience the plants’ healthy growth behind Polysolar panels.”

    The green wall panels in the hub are made from a synthetic material containing pockets, each holding a litre of soil and several plants. The pockets are fitted with a lining of carbon fibre on the back, which acts as an anode to receive electrons from the metabolism of plants and bacteria in the soil, and a carbon/catalyst plate on the front which acts as a cathode. 

    When a plant photosynthesises, energy from the sun is used to convert carbon dioxide into organic compounds that the plant needs to grow. Some of the compounds – such as carbohydrates, proteins and lipids – are leached into the soil where they are broken down by bacteria, which in turn release by-products, including electrons, as part of the process.

    Electrons have a negative charge so, when they are generated, protons (with a positive charge) are also created. When the anode and cathode are connected to each other by a wire acting as an external circuit, the negative charges migrate between those two electrodes. Simultaneously, the positive charges migrate from the anodic region to the cathode through a wet system, in this case the soil. The cathode contains a catalyst that enables the electrons, protons and atmospheric oxygen to recombine to form water, thus completing the circuit and permitting an electrical current to be generated in the external circuit.

    The P2P hub therfore generates electrical current from the combination of biological and physical elements. Each element of the hub is monitored separately, and members of the public can track the findings in real time, at a dedicated website and on a computer embedded in the hub itself.

    Margherita Cesca, Senior Architect and Director of MCMM Architettura, the hub’s designer, is pleased that it has garnered so much interest. “This prototype is intended to inspire the imagination, and encourage people to consider what could be achieved with these pioneering technologies. The challenging design incorporates and showcases green wall and solar panels as well as glass, creating an interesting element which sits beautifully within Cambridge University Botanic Garden,” she said.

    Bombelli added: “The long-term aim of the P2P solar hub research is to develop a range of self-powered sustainable buildings for multi-purpose use all over the world, from bus stops to refugee shelters.”

    P2P is an outreach activity developed under the umbrella of the BPV (BioPhotoVoltaic) project working in collaboration with green technology companies including MCMM, Polysolar and Scotscape. The BPV project includes scientists from the Departments of Biochemistry, Plant Sciences, Physics and Chemistry at the University of Cambridge, together with the University of Edinburgh, Imperial College London and the University of Cape Town.

    The innovative prototype solar hub will be unveiled at the Botanic Garden during an event at the Cambridge Science Festival, Trap the light fantastic: plant to power, on Tuesday 10 March.

    Green wall technology and semi-transparent solar panels have been combined to generate electrical current from a renewable source of energy both day and night.

    This prototype is intended to inspire the imagination, and encourage people to consider what could be achieved with these pioneering technologies
    Margherita Cesca, MCMM Architettura

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