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News from the Department of Physics.
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    The Global Alliance was formed in 2016 as a tripartite agreement between University of California, Berkeley, the University of Cambridge, and National University of Singapore in order to develop innovative research across the three universities to address research questions that could not be answered by one institution alone. There are three themes within the Global Alliance: Precision Medicine, Cities, and Smart Systems.

    Following a second funding call in May 2017, the Management Selection Committee has approved funding of the following five collaborative research projects:

    • "Opportunities for ecological adaptation to flood hazards in major global cities: London, Singapore and San Francisco" (Principal Investigator: Professor Thomas Spencer)
    • "Machine learning tools for personalised diagnosis in dementia"  (Principal Investigator: Professor Zoe Kourtzi)
    • "Healthy living in cities: my Personal Exposure Quality (MyPEQ)" (Principal investigator: Professor Rajasekhar Balasubramanian)
    • "Automating Approaches for Clinical Genome Interpretation" (Principal Investigator: Professor Steven  Brenner)
    • "Skin Deformation Assay Platforms for Pathogen- and Patient-Specific Diagnostics and Drug Development" (Principal Investigator: Dr Katherine Brown)

    The three universities are delighted to approve these collaborative projects which will build upon the combined strengths of the universities, as well as their distinctive regional insights, to develop unique solutions to global problems.

    Professor Paul Alivisatos, Executive Vice Chancellor and Provost, University of California, Berkeley

    Professor Chris Abell, Pro-Vice-Chancellor for Research, University of Cambridge

    Professor Ho Teck Hua, Senior Deputy President and Provost Designate, National University of Singapore

    UC Berkeley, the University of Cambridge and the National University of Singapore to support collaborative projects in themes including Precision Medicine, Cities and Smart Systems.

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  • 11/27/17--08:04: A force to be reckoned with
  • Think you know what gravity is? Think again. New research is revealing how little we know about this most mysterious of forces. Read the rest of the article from the latest version of CAM, the University's alumni magazine, here.

    Gravity is one of the universe's great mysteries. We decided to find out why.

    Supermassive black holes

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    The Dolby family gift is the largest philanthropic donation ever made to UK science, and will support the Cavendish Laboratory, the world-leading centre for physics research where Ray Dolby received his PhD in 1961. Thanks to this exceptional gift, the University has now surpassed the £1 billion milestone in its current £2 billion fundraising campaign. This is the second generous gift to Cambridge from the Dolby family, who donated £35 million to Pembroke College, Cambridge in 2015. The Dolby family is now the largest donor to the fundraising campaign, and the second-largest donor to the University in its 808-year history.

    In recognition of this gift, the flagship building of the Cavendish Laboratory redevelopment will be named the Ray Dolby Centre, and is expected to open in 2022. In addition, a new Ray Dolby Research Group will be established at the Cavendish, which will significantly expand research capability and expertise within the new building. The group, which will be led by a new endowed Ray Dolby Professorship, will build on and further strengthen the Cavendish Laboratory’s status and impact as one of the greatest centres of physics research in the world.

    “This unparalleled gift is a fitting tribute to Ray Dolby’s legacy, who changed the way the world listened - his research paved the way for an entire industry,” said Cambridge Vice-Chancellor Professor Stephen Toope. “A century from now, we can only speculate on which discoveries will alter the way we live our lives, and which new industries will have been born in the Cavendish Laboratory, in large part thanks to this extraordinarily generous gift.”

    “The Ray Dolby Centre will complete the development of the new Cavendish Laboratory. In addition to serving as a home for physics research at Cambridge, it will be a top-class facility for the nation,” said Professor Andy Parker, Head of the Cavendish Laboratory. “This extremely generous gift from the Dolby family is the most significant investment in physics research in generations, and a truly transformational gift in Cambridge’s history.”

    “The University of Cambridge played a pivotal role in Ray’s life, both personally and professionally,” said Dolby’s widow, Dagmar. “At Cambridge and at the Cavendish, he gained the formative education and insights that contributed greatly to his lifelong groundbreaking creativity, and enabled him to start his business.”

    “My father’s time at the Cavendish provided him with an environment where he got a world-class education in physics, and many of his successful ideas about noise reduction were stimulated by his Cambridge experience,” said Dolby’s son David. “Our family is pleased to be able to support the future scientists and innovators who will benefit from the thoughtfully designed Ray Dolby Centre.”

    Ray Dolby, who died in 2013 at the age of 80, came to Cambridge as a Marshall Scholar in 1957. He received his PhD from the Cavendish in 1961, and was a student and later a Fellow of Pembroke College.

    In 1965, he founded Dolby Laboratories in London and invented the Dolby System, an analogue audio encoding system that forever improved the quality of recorded sound. He moved the company in 1976 to San Francisco, where it has been headquartered ever since.

    The new Cavendish Laboratory will be its third home since its founding in 1874, and was first announced by the government in its 2015 Spending Review. It promised a £75 million investment in the Cavendish, which has been confirmed today, helping maintain Britain’s position at the forefront of physical sciences research. The funding will be delivered by the Engineering and Physical Sciences Research Council (EPSRC). Work on the new facility is expected to begin in 2019.

    “This generous £85 million donation from the Ray Dolby estate along with the £75 million government has already pledged is a testament to the importance of this facility and the UK’s leadership in science,” said Science Minister Jo Johnson. “The UK is one of the most innovative countries in the world, and through our Industrial Strategy and additional £2.3 billion investment for research and development we are ensuring our world-class research base goes from strength to strength for years to come.”

    “A successful nation invests in science, and this grant signals our intent to lead the world,” said Professor Philip Nelson, EPSRC's Chief Executive. “The facilities will be open to researchers across the country and encourage collaborative working between academics and institutions. Clearly Ray Dolby valued the university that nurtured his talents and, in making his bequest, has made a truly generous contribution to future generations.”

    Inset image: Ray Dolby

    The University of Cambridge has received an £85 million gift from the estate of Ray Dolby, founder of Dolby Laboratories and its world-renowned Dolby Noise Reduction, Dolby Surround, and successor audio signal processing technologies, which have revolutionised the audio quality of music, motion pictures, and television worldwide. 

    This unparalleled gift is a fitting tribute to Ray Dolby’s legacy, who changed the way the world listened - his research paved the way for an entire industry.
    Vice-Chancellor Professor Stephen Toope
    Entrance to Ray Dolby Centre at the Cavendish Laboratory

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    Read more about how clinical researchers, physicists, engineers and social scientists are among those collaborating as part of the Cancer Research UK Early Detection Programme.

    Kate Gross was just 36 years old when she died of cancer. Researchers at Cambridge – including her husband – are trying to ensure that others receive their diagnoses early enough to stop their cancer. 

    Kate Gross

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    One of the fundamental ideas of quantum theory is that quantum objects can exist both as a wave and as a particle, and that they don’t exist as one or the other until they are measured. This is the premise that Erwin Schrödinger was illustrating with his famous thought experiment involving a dead-or-maybe-not-dead cat in a box.

    “This premise, commonly referred to as the wave function, has been used more as a mathematical tool than a representation of actual quantum particles,” said David Arvidsson-Shukur, a PhD student at Cambridge’s Cavendish Laboratory, and the paper’s first author. “That’s why we took on the challenge of creating a way to track the secret movements of quantum particles.”

    Any particle will always interact with its environment, ‘tagging’ it along the way. Arvidsson-Shukur, working with his co-authors Professor Crispin Barnes from the Cavendish Laboratory and Axel Gottfries, a PhD student from the Faculty of Economics, outlined a way for scientists to map these ‘tagging’ interactions without looking at them. The technique would be useful to scientists who make measurements at the end of an experiment but want to follow the movements of particles during the full experiment.

    Some quantum scientists have suggested that information can be transmitted between two people – usually referred to as Alice and Bob – without any particles travelling between them. In a sense, Alice gets the message telepathically. This has been termed counterfactual communication because it goes against the accepted ‘fact’ that for information to be carried between sources, particles must move between them.

    “To measure this phenomenon of counterfactual communication, we need a way to pin down where the particles between Alice and Bob are when we’re not looking,” said Arvidsson-Shukur. “Our ‘tagging’ method can do just that. Additionally, we can verify old predictions of quantum mechanics, for example that particles can exist in different locations at the same time.”

    The founders of modern physics devised formulas to calculate the probabilities of different results from quantum experiments. However, they did not provide any explanations of what a quantum particle is doing when it’s not being observed. Earlier experiments have suggested that the particles might do non-classical things when not observed, like existing in two places at the same time. In their paper, the Cambridge researchers considered the fact that any particle travelling through space will interact with its surroundings. These interactions are what they call the ‘tagging’ of the particle. The interactions encode information in the particles that can then be decoded at the end of an experiment, when the particles are measured.

    The researchers found that this information encoded in the particles is directly related to the wave function that Schrödinger postulated a century ago. Previously the wave function was thought of as an abstract computational tool to predict the outcomes of quantum experiments. “Our result suggests that the wave function is closely related to the actual state of particles,” said Arvidsson-Shukur. “So, we have been able to explore the ‘forbidden domain’ of quantum mechanics: pinning down the path of quantum particles when no one is observing them.”

    Reference
    D. R. M. Arvidsson-Shukur, C. H. W. Barnes, and A. N. O. Gottfries. ‘Evaluation of counterfactuality in counterfactual communication protocols’. Physical Review A (2017). DOI: 10.1103/PhysRevA.96.062316

    Researchers from the University of Cambridge have taken a peek into the secretive domain of quantum mechanics. In a theoretical paper published in the journal Physical Review A, they have shown that the way that particles interact with their environment can be used to track quantum particles when they’re not being observed, which had been thought to be impossible. 

    We can verify old predictions of quantum mechanics, for example that particles can exist in different locations at the same time.
    David Arvidsson-Shukur
    2015-12-22 chemistry

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    As the global population increases, so too does energy demand. The threat of climate change means that there is an urgent need to find cleaner, renewable alternatives to fossil fuels that do not contribute extensive amounts of greenhouse gases with potentially devastating consequences on our ecosystem. Solar power is considered to be a particularly attractive source as on average the Earth receives around 10,000 times more energy from the sun in a given time than is required by human consumption.

    In recent years, in addition to synthetic photovoltaic devices, biophotovoltaics (BPVs, also known as biological solar-cells) have emerged as an environmentally-friendly and low-cost approach to harvesting solar energy and converting it into electrical current. These solar cells utilise the photosynthetic properties of microorganisms such as algae to convert light into electric current that can be used to provide electricity.

    During photosynthesis, algae produce electrons, some of which are exported outside the cell where they can provide electric current to power devices. To date, all the BPVs demonstrated have located charging (light harvesting and electron generation) and power delivery (transfer to the electrical circuit) in a single compartment; the electrons generate current as soon as they have been secreted.

    In a new technique described in the journal Nature Energy, researchers from the departments of Biochemistry, Chemistry and Physics have collaborated to develop a two-chamber BPV system where the two core processes involved in the operation of a solar cell – generation of electrons and their conversion to power – are separated.

    “Charging and power delivery often have conflicting requirements,” explains Kadi Liis Saar, of the Department of Chemistry. “For example, the charging unit needs to be exposed to sunlight to allow efficient charging, whereas the power delivery part does not require exposure to light but should be effective at converting the electrons to current with minimal losses.”

    Building a two-chamber system allowed the researchers to design the two units independently and through this optimise the performance of the processes simultaneously.

    “Separating out charging and power delivery meant we were able to enhance the performance of the power delivery unit through miniaturisation,” explains Professor Tuomas Knowles from the Department of Chemistry and the Cavendish Laboratory. “At miniature scales, fluids behave very differently, enabling us to design cells that are more efficient, with lower internal resistance and decreased electrical losses.”

    The team used algae that had been genetically modified to carry mutations that enable the cells to minimise the amount of electric charge dissipated non-productively during photosynthesis. Together with the new design, this enabled the researchers to build a biophotovoltaic cell with a power density of 0.5 W/m2, five times that of their previous design. While this is still only around a tenth of the power density provided by conventional solar fuel cells, these new BPVs have several attractive features, they say.

    "While conventional silicon-based solar cells are more efficient than algae-powered cells in the fraction of the sun’s energy they turn to electrical energy, there are attractive possibilities with other types of materials," says Professor Christopher Howe from the Department of Biochemistry. “In particular, because algae grow and divide naturally, systems based on them may require less energy investment and can be produced in a decentralised fashion."

    Separating the energy generation and storage components has other advantages, too, say the researchers. The charge can be stored, rather than having to be used immediately – meaning that the charge could be generated during daylight and then used at night-time.

    While algae-powered fuel cells are unlikely to generate enough electricity to power a grid system, they may be particularly useful in areas such as rural Africa, where sunlight is in abundance but there is no existing electric grid system. In addition, whereas semiconductor-based synthetic photovoltaics are usually produced in dedicated facilities away from where they are used, the production of BPVs could be carried out directly by the local community, say the researchers.

    “This a big step forward in the search for alternative, greener fuels,” says Dr Paolo Bombelli, from the Department of Biochemistry. “We believe these developments will bring algal-based systems closer to practical implementation.”

    The research was supported by the Leverhulme Trust, the Engineering and Physical Sciences Research Council and the European Research Council.

    Reference
    Saar, KL et al. Enhancing power density of biophotovoltaics by decoupling storage and power delivery. Nature Energy; 9 Jan 2018; DOI: 10.1038/s41560-017-0073-0

    A new design of algae-powered fuel cells that is five times more efficient than existing plant and algal models, as well as being potentially more cost-effective to produce and practical to use, has been developed by researchers at the University of Cambridge. 

    This a big step forward in the search for alternative, greener fuels
    Paolo Bombelli
    Artist' impression
    Researcher Profile: Dr Paolo Bombelli

    Dr Paolo Bombelli is a post-doctoral researcher in the Department of Biochemistry, where his research looks to utilise the photosynthetic and metabolic activity of plants, algae and bacteria to create biophotovoltaic devices, a sustainable source of renewable current. He describes himself as “a plants, algae and bacteria electrician”.

    “Photosynthesis generates a flow of electrons that keeps plants, algae and other photosynthetic organisms alive,” he explains. “These electrons flow though biological wires and, like the electrical current obtained from a battery and used to power a radio, they are the driving force for any cellular activity.”

    Dr Bombelli’s fascination with this area of research began during his undergraduate studies at the University of Milan.

    “Plants, algae and photosynthetic bacteria are the oldest, most common and effective solar panels on our planet,” he says. “For billions of years they have been harnessing the energy of the sun and using it to provide oxygen, food and materials to support life. With my work I aim to provide new ways to embrace the potential of these fantastic photosynthetic organisms.”

    His work is highly cross-disciplinary, with input from the Departments of Biochemistry, Plant Sciences, Chemistry and Physics, and the Institute for Manufacturing, as well as from researchers at Imperial College London, UCL, the University of Brighton, the Institute for Advanced Architecture of Catalonia in Spain and the University of Cape Town, South Africa.

    “Universities are great places to work and so they attract many people,” he says. “People choose to come to Cambridge because they know the ideas they generate here will go on to change the world.”

    In 2016, Dr Bombelli won a Public Engagement with Research Award by the University of Cambridge for his work engaging audiences at more than 40 public events, including science festivals and design fairs, reaching thousands of people in seven countries. His outreach work included working with Professor Chris Howe to develop a prototype ‘green bus shelter’ where plants, classical solar panels and bio-electrochemical systems operate in synergy in a single structure.

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    An international team led by Dr Renske Smit from the Kavli Institute of Cosmology at the University of Cambridge used the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile to open a new window onto the distant Universe, and have for the first time been able to identify normal star-forming galaxies at a very early stage in cosmic history with this telescope. The results are reported in the journal Nature, and will be presented at the 231st meeting of the American Astronomical Society.

    Light from distant objects takes time to reach Earth, so observing objects that are billions of light years away enables us to look back in time and directly observe the formation of the earliest galaxies. The Universe at that time, however, was filled with an obscuring ‘haze’ of neutral hydrogen gas, which makes it difficult to see the formation of the very first galaxies with optical telescopes.

    Smit and her colleagues used ALMA to observe two small newborn galaxies, as they existed just 800 million years after the Big Bang. By analysing the spectral ‘fingerprint’ of the far-infrared light collected by ALMA, they were able to establish the distance to the galaxies and, for the first time, see the internal motion of the gas that fuelled their growth.

    “Until ALMA, we’ve never been able to see the formation of galaxies in such detail, and we’ve never been able to measure the movement of gas in galaxies so early in the Universe’s history,” said co-author Dr Stefano Carniani, from Cambridge’s Cavendish Laboratory and Kavli Institute of Cosmology.

    The researchers found that the gas in these newborn galaxies swirled and rotated in a whirlpool motion, similar to our own galaxy and other, more mature galaxies much later in the Universe’s history. Despite their relatively small size – about five times smaller than the Milky Way – these galaxies were forming stars at a higher rate than other young galaxies, but the researchers were surprised to discover that the galaxies were not as chaotic as expected.

    “In the early Universe, gravity caused gas to flow rapidly into the galaxies, stirring them up and forming lots of new stars – violent supernova explosions from these stars also made the gas turbulent,” said Smit, who is a Rubicon Fellow at Cambridge, sponsored by the Netherlands Organisation for Scientific Research. “We expected that young galaxies would be dynamically ‘messy’, due to the havoc caused by exploding young stars, but these mini-galaxies show the ability to retain order and appear well regulated. Despite their small size, they are already rapidly growing to become one of the ‘adult’ galaxies like we live in today.”

    The data from this project on small galaxies paves the way for larger studies of galaxies during the first billion years of cosmic time. The research was funded in part by the European Research Council and the UK Science and Technology Facilities Council (STFC).

    Reference:
    Renske Smit et al. ‘Rotation in [C II]-emitting gas in two galaxies at a redshift of 6.8.’ Nature (2018). DOI: 10.1038/nature24631

    Astronomers have looked back to a time soon after the Big Bang, and have discovered swirling gas in some of the earliest galaxies to have formed in the Universe. These ‘newborns’ – observed as they appeared nearly 13 billion years ago – spun like a whirlpool, similar to our own Milky Way. This is the first time that it has been possible to detect movement in galaxies at such an early point in the Universe’s history. 

    We’ve never been able to see the formation of galaxies in such detail, and we’ve never been able to measure the movement of gas in galaxies so early in the Universe’s history.
    Stefano Carniani
    Artist's impression of spinning galaxy
    Researcher profile: Renske Smit

    Dr Renske Smit is a postdoctoral researcher and Rubicon Fellow at the Kavli Institute of Cosmology and is supported by the Netherlands Organisation for Scientific Research. Prior to arriving in Cambridge in 2016, she was a postdoctoral researcher at Durham University and a PhD student at Leiden University in the Netherlands.

    Her research aims to understand how the first sources of light in the Universe came to be. In her daily work, she studies images of deep space, taken by telescopes such as the Hubble Space Telescope. To gather data, she sometimes travels to places such as Chile or Hawaii to work on big telescopes.

    “In Cambridge, I have joined a team working on the James Webb Space Telescope, the most ambitious and expensive telescope ever built,” she says. “With this telescope, we might be able to see the very first stars for the first time. To have this kind of privileged access to world-leading data is truly a dream come true.

    “I would like to contribute to changing the perception of what a science professor looks like. Women in the UK and worldwide are terribly underrepresented in science and engineering and as a result, people may feel women either don’t have the inclination or the talent to do science. I hope that one day I will teach students that don’t feel they represent the professor stereotype and make them believe in their own talent.”

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    An international team of researchers led by the University of Cambridge found that the addition of potassium iodide ‘healed’ the defects and immobilised ion movement, which to date have limited the efficiency of cheap perovskite solar cells. These next-generation solar cells could be used as an efficiency-boosting layer on top of existing silicon-based solar cells, or be made into stand-alone solar cells or coloured LEDs. The results are reported in the journal Nature.

    The solar cells in the study are based on metal halide perovskites – a promising group of ionic semiconductor materials that in just a few short years of development now rival commercial thin film photovoltaic technologies in terms of their efficiency in converting sunlight into electricity. Perovskites are cheap and easy to produce at low temperatures, which makes them attractive for next-generation solar cells and lighting.

    Despite the potential of perovskites, some limitations have hampered their efficiency and consistency. Tiny defects in the crystalline structure of perovskites, called traps, can cause electrons to get ‘stuck’ before their energy can be harnessed. The easier that electrons can move around in a solar cell material, the more efficient that material will be at converting photons, particles of light, into electricity. Another issue is that ions can move around in the solar cell when illuminated, which can cause a change in the bandgap – the colour of light the material absorbs.  

    “So far, we haven’t been able to make these materials stable with the bandgap we need, so we’ve been trying to immobilise the ion movement by tweaking the chemical composition of the perovskite layers,” said Dr Sam Stranks from Cambridge’s Cavendish Laboratory, who led the research. “This would enable perovskites to be used as versatile solar cells or as coloured LEDs, which are essentially solar cells run in reverse.”

    In the study, the researchers altered the chemical composition of the perovskite layers by adding potassium iodide to perovskite inks, which then self-assemble into thin films. The technique is compatible with roll-to-roll processes, which means it is scalable and inexpensive. The potassium iodide formed a ‘decorative’ layer on top of the perovskite which had the effect of ‘healing’ the traps so that the electrons could move more freely, as well as immobilising the ion movement, which makes the material more stable at the desired bandgap.

    The researchers demonstrated promising performance with the perovskite bandgaps ideal for layering on top of a silicon solar cell or with another perovskite layer – so-called tandem solar cells. Silicon tandem solar cells are the most likely first widespread application of perovskites. By adding a perovskite layer, light can be more efficiently harvested from a wider range of the solar spectrum.

    “Potassium stabilises the perovskite bandgaps we want for tandem solar cells and makes them more luminescent, which means more efficient solar cells,” said Stranks, whose research is funded by the European Union and the European Research Council’s Horizon 2020 Programme. “It almost entirely manages the ions and defects in perovskites.”

    “We’ve found that perovskites are very tolerant to additives – you can add new components and they’ll perform better,” said first author Mojtaba Abdi-Jalebi, a PhD candidate at the Cavendish Laboratory who is funded by Nava Technology Limited. “Unlike other photovoltaic technologies, we don’t need to add an additional layer to improve performance, the additive is simply mixed in with the perovskite ink.”

    The perovskite and potassium devices showed good stability in tests, and were 21.5% efficient at converting light into electricity, which is similar to the best perovskite-based solar cells and not far below the practical efficiency limit of silicon-based solar cells, which is (29%). Tandem cells made of two perovskite layers with ideal bandgaps have a theoretical efficiency limit of 45% and a practical limit of 35% - both of which are higher than the current practical efficiency limits for silicon. “You get more power for your money,” said Stranks.

    The research has also been supported in part by the Royal Society and the Engineering and Physical Sciences Research Council. The international team included researchers from Cambridge, Sheffield University, Uppsala University in Sweden and Delft University of Technology in the Netherlands.

    Reference:
    Mojtaba Abdi-Jalebi et al. ‘Maximising and Stabilising Luminescence from Halide Perovskites with Potassium Passivation.’ Nature (2018). DOI: 10.1038/nature25989

    A simple potassium solution could boost the efficiency of next-generation solar cells, by enabling them to convert more sunlight into electricity. 

    Perovskites are very tolerant to additives – you can add new components and they’ll perform better.
    Mojtaba Abdi-Jalebi
    Atomic scale view of perovskite crystal formation

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    Joanna Waldie

    My research focuses on developing devices that can manipulate electrons one at a time. I also happen to have long gaps on my CV that take some creativity to explain in job interviews. This is because I’ve had mental health problems since I was a teenager.  During treatment for this, I’ve been privileged to meet some wonderful people with a variety of mental health conditions and to gain a little insight into their struggles.

    Mental health conditions are often invisible. If I have a broken leg or a sore throat then it doesn’t take much for my colleagues to understand that I need time off work. If my mental health is bad then the onus is on me to explain to other people why I need time off work.

    I worry that people will think I am silly, or oversensitive, or lazy, or skiving. However, the first person you need to convince that it’s OK to have time off is yourself. It feels like a great step forward when you do.

    There are a lot of misconceptions about mental illnesses, not least because their invisibility makes awareness of their prevalence remain low. If I tell someone what mental health conditions I have, I have no idea what this will mean to them, and whether it will match the reality of how I feel. This is particularly the case in the multicultural research environment, where different cultures may have very different understandings of mental health.

    As researchers we have succeeded in our University studies and got our PhDs. We are used to solving problems, achieving highly and getting stuff done.

    When faced with a mental health condition, we feel desperately that we need to understand and solve the problem, and soon. But even after many years I do not fully understand my mental health problems. I cannot fix them or solve them as I would a problem in the lab.

    It has taken me years to learn to spot triggers and recognise warning signs when things are getting bad, and to learn some things that sometimes help. I have learned a huge amount, but there is still much I don’t understand about this illness.

    I have told few colleagues about my health problems, but those I have told have been supportive. I’ve benefited from some fantastic services at the University including the staff counselling and occupational health services. That support – at work and from family and friends – makes a huge difference.

    There are still challenges – my ongoing mental health problems are classed as a disability, and that meant I had to tick a box labelling me as a “disabled person” when I started this job in order to qualify for reasonable adjustments. Not everyone would feel OK about that. These labels can create barriers to people coming forward to seek help.

    Researchers often have to move around a lot to advance their careers, doing a series of short-term contracts in several places. If someone with a mental health condition comes to the UK for an 18-month postdoc job, it might take them a while to understand how to access treatment in the UK. They might wait for months to be seen by a specialist. And treatment in the UK might be very different to what they have known in in their home country.

    I’ve been very lucky in this respect. When I was a PhD student, my College provided me with free accommodation near to the hospital where I was being treated so I didn’t have to move back to live with my parents and start all over again on a waiting list.

    My fellowship is normally only open to people who are moving to Cambridge. But the selection panel took into account that I wanted to stay in Cambridge to continue to access treatment and support at the same clinic.

    The sector needs to do more to help researchers who have moved for a job, uprooting themselves from their support networks.

    Research is challenging. In trying to do things no one has ever done before there are always setbacks. For someone with a mental health condition, you can go from one setback in the lab to deep despair in the time it takes to say ‘Supercalifragilisticexpialidocious’.

    Sometimes I wish having someone beside me to give moral support during difficult experiments counted as a ‘reasonable adjustment’. But I am lucky to have colleagues and a boss who do support me.

    As a researcher you need to believe in your research ideas and your ability to carry them out. You need to be able to sell your research. You need to be excited by your research and be able to convince other people to get excited about it, to publish it, to fund it. This is hard to do if you are feeling depressed, and you don’t even feel like life is worth living. It’s really hard.

    But friends and colleague can make a real difference in helping people with mental health problems to flourish in their research.

    A greater openness about mental health in the research community will surely benefit us all.

    Herchel Smith postdoctoral research fellow in Physics Dr Joanna Waldie shares her personal story to support Mental Health Awareness Week

    When I need time off, I worry that people will think I am silly, or oversensitive, or lazy, or skiving - the first person you need to convince that it’s OK is yourself
    Joanna Waldie

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    The researchers, whose work appears in the journal Science, say their findings could be a “game changer” by allowing the energy from sunlight absorbed in these materials to be captured and used more efficiently. 

    Lightweight semiconducting plastics are now widely used in mass market electronic displays such as those found in phones, tablets and flat-screen televisions.  However, using these materials to convert sunlight into electricity to make solar cells is far more complex. 

    The photo-excited states – when photons of light are absorbed by the semiconducting material – need to move so that they can be “harvested” before they lose their energy.  These excitations typically only travel about 10 nanometres in plastic (or polymeric) semiconductors, so researchers need to build tiny structures patterned at the nanoscale to maximise the “harvest”.

    Dr Xu-Hui Jin and colleagues at the University of Bristol developed a new way to make highly ordered crystalline semiconducting structures using polymers.

    Dr Michael Price of Cambridge's Cavendish Laboratory measured the distance that the photo-exited states travelled, which reached distances of 200 nanometres – 20 times further than was previously possible.

    200 nanometres is especially significant because it is greater than the thickness of material needed to completely absorb ambient light, making these polymers more suitable as “light harvesters” for solar cells and photodetectors.

    “The gain in efficiency would actually be for two reasons: first, because the energetic particles travel further, they are easier to “harvest”, and second, we could now incorporate layers around 100 nanometres thick, which is the minimum thickness needed to absorb all the energy from light – the so-called optical absorption depth,” said co-author Dr George Whittell from the University of Bristol. “Previously, in layers this thick, the particles were unable to travel far enough to reach the surfaces.”

    “The distance that energy can be moved in these materials comes as a big surprise and points to the role of unexpected quantum coherent transport processes,” said co-author Professor Sir Richard Friend from Cambridge's Cavendish Laboratory, and a Fellow of St John's College. 

    The research team now plans to prepare structures thicker than those in the current study and greater than the optical absorption depth, with a view to building prototype solar cells based on this technology.

    They are also preparing other structures capable of using light to perform chemical reactions, such as the splitting of water into hydrogen and oxygen.

    Reference:
    Xu-Hui Jin et al.Long-range exciton transport in conjugated polymer nanofibers prepared by seeded growth.’ Science (2018). DOI: 10.1126/science.aar8104 

    Adapted from a University of Bristol press release. 

    Scientists from the Universities of Cambridge and Bristol have found a way to create plastic semiconductor nanostructures that absorb light and transport its energy 20 times further than has been previously observed, paving the way for more flexible and more efficient solar cells and photodetectors. 

    The distance that energy can be moved in these materials comes as a big surprise.
    Richard Friend
    Image showing light emission from the polymeric nanostructures and schematic of a single nanostructure

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