An international team of researchers, led by the University of Cambridge, has estimated the amount of hydrocarbons – the primary ingredient in crude oil – that are produced by a massive population of photosynthetic marine microbes, called cyanobacteria. These organisms in turn support another population of bacteria that ‘feed’ on these compounds.

In the study, conducted in collaboration with researchers from the University of Warwick and MIT, and published today (5 October) in the journal Proceedings of the National Academy of Sciences of the USA, the scientists measured the amount of hydrocarbons in a range of laboratory-grown cyanobacteria and used the data to estimate the amount produced in the oceans.

Although each individual cell contains minuscule quantities of hydrocarbons, the researchers estimated that the amount produced by two of the most abundant cyanobacteria in the world – Prochlorococcus and Synechococcus – is more than two million tonnes in the ocean at any one time. This indicates that these two groups alone produce between 300 and 800 million tonnes of hydrocarbons per year, yet the concentration at any time in unpolluted areas of the oceans is tiny, thanks to other bacteria that break down the hydrocarbons as they are produced.

“Hydrocarbons are ubiquitous in the oceans, even in areas with minimal crude oil pollution, but what hadn’t been recognised until now is the likely quantity produced continually by living oceanic organisms,” said Professor Christopher Howe from Cambridge’s Department of Biochemistry, the paper’s senior author. “Based on our laboratory studies, we believe that at least two groups of cyanobacteria are responsible for the production of massive amounts of hydrocarbons, and this supports other bacteria that break down the hydrocarbons as they are produced.”

The scientists argue that the cyanobacteria are key players in an important biogeochemical cycle, which they refer to as the short-term hydrocarbon cycle. The study suggests that the amount of hydrocarbons produced by cyanobacteria dwarfs the amount of crude oil released into the seas by natural seepage or accidental oil spills.

However, the hydrocarbons produced by cyanobacteria are continually broken down by other bacteria, keeping the overall concentrations low. When an event such as an oil spill occurs, hydrocarbon-degrading bacteria are known to spring into action, with their numbers rapidly expanding, fuelled by the sudden local increase in their primary source of energy.

The researchers caution that their results do not in any way diminish the enormous harm caused by oil spills. Although some microorganisms are known to break down hydrocarbons in oil spills, they cannot repair the damage done to marine life, seabirds and coastal ecosystems.

“Oil spills cause widespread damage, but some parts of the marine environment recover faster than others,” said Dr David Lea-Smith, a postdoctoral researcher in the Department of Biochemistry, and the paper’s lead author. “This cycle is like an insurance policy – the hydrocarbon-producing and hydrocarbon-degrading bacteria exist in equilibrium with each other, and the latter multiply if and when an oil spill happens. However, these bacteria cannot reverse the damage to ecosystems which oil spills cause.”

The researchers stress the need to test if their findings are supported by direct measurements on cyanobacteria growing in the oceans. They are also interested in the possibility of harnessing the hydrocarbon production potential of cyanobacteria industrially as a possible source of fuel in the future, although such work is at a very early stage.

Reference:
Lea-Smith, D. et. al. “Contribution of cyanobacterial alkane production to the ocean hydrocarbon cycle.” PNAS (2015). DOI: 10.1073/pnas.1507274112

Trainee doctors think they are being asked to prolong some patients’ lives unnecessarily and describe such cases as being tantamount to torture and abuse, according to a new study.

The research, led by Elizabeth Dzeng, a Gates Cambridge Scholar at the University of Cambridge, is the first to focus on US doctors’ moral distress surrounding resuscitation and treatments that they believe may be futile at the end of life and has implications for the UK as more power is handed from doctors to patients’ representatives around end of life issues.

The qualitative study, titled “Moral Distress Amongst American Physician Trainees Regarding Futile Treatments at the End of Life: A Qualitative Inquiry”, is published in the Journal of General Internal Medicine.

Elizabeth conducted in-depth interviews with 22 physician trainees in internal medicine at three accredited medical centres in the US and asked how they reacted and responded to ethical challenges arising in the context of perceived futile treatments at the end of life and how they felt about its ethical implications.

It found that doctors who are required to perform procedures such as resuscitation which they feel are futile or harmful have significant moral qualms that they are prolonging suffering as opposed to providing care. Some cope with these by developing detached and dehumanising attitudes towards patients.

One said of a patient: “It felt horrible, like I was torturing him. He was telling us we were torturing him. I did not think we were doing the right things.”

Another said: “I agree with giving the patient’s choice, but oftentimes it’s the family member. If the patient says, “Torture me, I want everything done.” Fine. The family member is doing it for other reasons. Like guilt; they can’t let go.”

Ways of coping ranged from formal and informal conversations with colleagues and superiors about the emotional and ethical challenges of providing care at the end of life to a tendency among some to dehumanise the patient.

One trainee said: “We’re abusing a body and I get that, but as long as I remember I’m only abusing a body and not a person, it’s okay. Frequently when it’s an inappropriate code, that’s what’s happening.”

Trainees also said that the hierarchical nature of their relationship with other doctors meant they felt powerless to have any influence on decisions.

Dzeng [2011] is completing a PhD on medical sociology and ethics and is also a fellow in General Internal Medicine at the Johns Hopkins School of Medicine. She said: “Our study sheds light on a significant cause of moral distress amongst physician trainees when they feel obligated to provide treatments at the end of life that they believe to be futile or harmful. Their words – ‘torture’, ‘gruesome’, ‘abuse’, ‘mutilate’ and ‘cruel’ evoke images more fitting of penal regimes than hospitals. The moral toll exacted upon these physicians is evident in descriptions such as feeling ‘violated’ and ‘traumatised’. Previous research shows that moral distress can have significant negative effects on job satisfaction, psychological and physical well-being and self-image, resulting in burnout and thoughts of quitting.”

The paper is part of a larger study investigating the influence of institutional cultures and policies on physicians’ and trainees’ views on resuscitation orders. A previous paper found that in hospitals with cultures and policies which prioritised patient autonomy over the patients’ best interest, physicians tended to give patients a menu of choices without guidance or recommendations over whether resuscitation would be beneficial or merely prolong suffering. It explored the effect of moves towards greater patient autonomy over end of life decisions. Although this was an understandable reaction to the paternalistic approach often adopted by doctors in the past, the paper voiced fears that the pendulum may have swung too far, to the detriment of patients themselves.

Fully exploiting the Government’s education data could help to bridge the skills gap that is holding back UK businesses, Cambridge expert Professor Anna Vignoles has said at aRustat Conference session on the application of Big Data, held at Jesus College.

The UK’s skills gap has been highlighted by both the Confederation of British Industry(CBI) and the Chartered Institute of Management Accountants (CIMA) this year. The CBI reported that over half of employers (55%) are not confident there will be enough people available in the future with the necessary skills to fill their high-skilled jobs¹.

In the last ten years, the Government has allowed researchers to access some of its educational data under secure conditions. Academics including Vignoles have recently mapped the journeys taken by students from the age of four right through to employment.

During a session on the application of Big Data and data driven business models, Vignoles argued that researchers could now use earnings data to determine which skills are in greater demand in the labour market, and feed this back into policy to ensure that the education system teaches the skills needed by UK companies.

“Many firms have difficulties recruiting people with the right skills, and are having to pay a big premium for some skills. Although we can survey firms about their needs, the results can be misleading, not least because only a select group of companies may respond,” said Vignoles.

“I have been working with colleagues to accurately analyse graduate earnings, using anonymous Government administrative data. This type of analysis can show how earnings vary for different types of graduates, and so indicate which skills are in short supply.

“For example, let’s say that the next stage of our research reveals that graduates with strong analytical skills are in demand. This data could inform students, universities and policy makers, and may result in courses offering more training in analytical skills. More graduates will then have the analytical skills needed by businesses, and the skills gap should start to close.

“Of course, providing information is not enough to change policy, but without good data any policy development is likely to be ineffective. The UK is world-leading when it comes to education data, but it is only recently that a Big Data approach has been used to look at graduate earnings. Fully exploiting the Government’s education data could help to bridge the UK skills gap.

“However there should always be strict limitations on the way data is used to ensure that people’s privacy is protected. We need to have an informed debate about the extent to which members of the public are happy for data collected by the state to be used in this way.”

Vignoles sits on the steering group of the University of Cambridge’s Big Data Research Initiative. This brings together researchers to address challenges presented by access to unprecedented volumes of data, as well as important issues around law, ethics and economics, in order to apply Big Data to solve challenging problems for society.

Rustat Conferences are held three times a year at Jesus College, Cambridge, with this conference focusing on Big Data. Other sessions explored the Internet of Things, sharing data and respecting individual rights without disrupting new business models, and the legal aspects of Big Data. Rustat Conferences offer an opportunity for decision-makers from the frontlines of politics, business, finance, the media and education to discuss vital issues with leading academic experts.

The study, which could see over 500 students receive mindfulness training, aims to measure its effectiveness in managing stress amongst students, particularly at exam time, and whether it helps in other factors such as sleep and wellbeing. It will also explore whether the training affects students’ use of mental health treatment and support services.

Mindfulness involves the use of meditation techniques and self-awareness. Originally developed to help patients with chronic pain cope with their condition, it is now a recognised – and clinically-proven – way of helping individuals cope with depression, anxiety and stress.

Géraldine Dufour, Head of Counselling at the University, says: “University life can be stressful at time for students, as they develop the skills to live and study independently. Developing resilience and the skills to cope with stress is key so that students can make the most of life in the collegiate university and when they leave. The university counselling service offers many opportunities for students to develop their skills through an extensive programme of workshops, groups and individual counselling. We believe mindfulness could be a powerful tool to help them, in addition to the other counselling services we offer. This research project will help us determine if mindfulness is a good use of resources.”

From October, undergraduates and postgraduates at the University of Cambridge will be invited to register for a free, eight-week mindfulness training course called Mindfulness Skills for Students, which will be led by Dr Elizabeth English, the University’s Mindfulness Practitioner. The course is a group-based training programme based on the course bookMindfulness: A Practical Guide to Finding Peace in a Frantic World, by Mark Williams and Danny Penman, and adapted for Cambridge students. It consists of one 90-minute session and seven 75-minute sessions. Participants are also requested to do some home practice and reading every week.

Students will be allocated at random to two groups – one to receive training immediately, the second to be deferred twelve months. All students – both those who take the course and those whose training is deferred – will record their stress levels using a smartphone app during the exam period, while activity monitors will record their physical activity and sleep patterns.

“The academic year provides a very real ‘natural experiment’,” says Dr Julieta Galante from the Department of Psychiatry, who will carry out the research together with Professor Peter Jones. “Students receive training, practice at home, then face a ‘pressure point’ – their exams. We hope that our study will help us answer the question of whether the provision of mindfulness training, which we know to be effective in other settings, can help students throughout the year and particularly at exam time.”

The level of support available to students at Cambridge is unparalleled in most other universities. The University Counselling Service, one of the best funded in the country, includes counsellors as well as mental health advisors and supplements the support available to students from specialist staff in the colleges such as college nurses and chaplains. In the previous academic year, over 1,500 people were seen for counselling – this represents around one in 12 of the student population. Its Mindfulness Skills for Students programme is believed to be the largest such programme in any university.

Students wishing to register for the evaluation study of the Mindfulness Training Programme should visit the mindfulness website or emailmindfulstudentstudy@medschl.cam.ac.uk.

• www.facebook.com/mindfulstudentstudy
• twitter.com/MSSatUoC

The findings, published today (September 28) in the journal Nature Genetics, suggest that the reproductive cells or ‘eggs’ in a woman’s ovaries (known as oocytes) that repair damaged DNA more efficiently survive longer. This results in a later age at menopause, which marks the end of a woman’s reproductive lifetime. Previous research has shown that DNA is regularly damaged by age and by toxic substances such as cigarette smoke – hence women who smoke go through menopause 1-2 years earlier on average than non-smokers.

Our cells have many mechanisms to detect and repair such damage, but cells die when too much damage accumulates. DNA is also damaged and repaired during the production of eggs – therefore these genes might also act to enhance a woman’s pool of eggs which is set in early life.

In a collaboration involving scientists from 177 institutions worldwide, the authors undertook a genome-wide association study of almost 70,000 women of European ancestry.

“Many women today are choosing to have babies later in life, but they may find it difficult to conceive naturally because fertility starts to diminish at least 10 years before menopause,” said Dr Anna Murray from the University of Exeter, and the paper’s senior author. “Our research has substantially increased our understanding of how reproductive ageing in women happens, which we hope will lead to the development of new treatments to avoid early menopause.”

Dr John Perry from the Medical Research Council (MRC) Epidemiology Unit at the University of Cambridge co-led the study, and said: “We have known for some time that the age at which women go through menopause is partly determined by genes. This study now tells us that there are likely hundreds of genes involved, each altering menopause age by anything from a few weeks to a year. It is striking that genes involved in DNA repair have such an important influence on the age of menopause, which we think is due to their effect on how quickly a woman’s eggs are lost throughout her lifetime.”

The researchers also used these genetic findings to examine links between menopause and other health conditions. They predict that every one year later that menopause occurs increases the risk of developing breast cancer by 6%.

Dr Deborah Thompson from the Department of Public Health and Primary Care at the University of Cambridge also co-led this large international collaboration and said: “One particularly convincing finding was that going through menopause earlier reduces your chances of developing breast cancer and we think this is because these women have less exposure to the hormone oestrogen over their lifetime.”

The next step is to understand in more detail how the genetic variations found in this study are causing alterations in the timing of menopause. Uncovering these mechanisms will hopefully lead to better treatment for conditions linked to menopause, such as infertility and also improved understanding of the heath impact of menopause, such as risk of osteoporosis and heart disease.

Menopause usually occurs between ages 40 to 60 years old, indicated by the end of natural menstrual cycles and in many women by physical symptoms, such as hot flushes, disrupted sleep, and reduced energy levels. Natural menopause before the age of 40 is often called “primary ovarian insufficiency” and occurs in 1% of women.

Adapted from a University of Exeter press release.

Reference:
Felix R Day et al. ‘Large-scale genomic analyses link reproductive aging to hypothalamic signaling, breast cancer susceptibility and BRCA1-mediated DNA repair.’ Nature Genetics (2015). DOI: 10.1038/ng.3412. 

The small tumours concealed in the adrenal gland are “unmasked” in early pregnancy, when a sudden surge of hormones fires them into life, leading to raised blood pressure and causing risk to patients.

New research published today in the New England Journal of Medicine conducted by a team led by Professor Morris Brown, professor of clinical pharmacology at Cambridge University and a Fellow of Gonville & Caius College, identifies this small group of lurking tumours for the first time, and explains why they behave as they do.

The study means that, when patients are found to have high blood pressure early in pregnancy, doctors will now be encouraged to consider that the cause could be the tumours, which can be easily treated. Currently, adrenal tumours are not usually suspected as the cause of high blood pressure in pregnancy, and so go undiagnosed.

Brown and an international group of PhD students including first-author Ada Teo of Newnham College used a combination of state-of-the-art gene “fingerprinting” technology and old-fashioned deduction from patient case histories to work out that the otherwise benign tumours harbour genetic mutations that affect cells in the adrenal gland.

The mutation means the adrenal cells are given false information and their clock is effectively turned back to “childhood”, returning them to their original state as ovary cells. They then respond to hormones released in pregnancy, producing increased levels of the salt-regulating hormone aldosterone.

Aldosterone in turn regulates the kidneys to retain more salt and hence water, pushing up blood pressure. High blood pressure – also known as hypertension – can be fatal, since it greatly increases the risk of stroke and heart attack.

The new findings build on a growing body of research focusing on the adrenal gland and blood pressure. Sixty years ago, the American endocrinologist Dr Jerome Conn first observed that large benign tumours in the adrenal gland can release aldosterone and increase blood pressure (now known as Conn’s Syndrome).

Brown and his team have previously found a group of much smaller tumours, arising from the outer part of the gland, that have the same effect. The latest discovery drills down still further, revealing that roughly one in ten of this group has a mutation that makes the cells receptive to pregnancy hormones.

Brown said: “This is an example of what modern scientific techniques, and collaborations among doctors and scientists, allow you to do [through a form of genetic fingerprinting]. Conditions are often around for 60 years which we have had no explanation for, and now we can get to the heart of what has gone wrong.”

But the discovery also relied on what doctors call “clinical pattern recognition” – using experience to spot similarities. Brown was able to link together the cases of two pregnant women almost ten years apart and a woman in early menopause. All suffered high blood pressure, leading him to screen their adrenal tumours and identify a matching genetic mutation.

Pregnant women found to have the newly identified subset of tumours can now be identified more readily, and the tumours either treated with drugs or potentially even removed.

The research was funded by the Wellcome Trust, National Institute for Health Research, British Heart Foundation and A* Singapore.

In the animal kingdom, the flashiest males often have more luck attracting a mate. But when your predators hunt by sight, this can pose an interesting problem.

Like many species, lizards use bright colours for sexual signalling to attract females and intimidate rival males. A new study published in Ecology and Evolution by Kate Marshall from the University of Cambridge’s Department of Zoology and Martin Stevens from the University of Exeter’s Centre for Ecology and Conservation has provided evidence that this signalling comes at a cost.

Using models that replicated the colouration of male and female wall lizards found on the Greek islands of Skopelos and Syros, they found that the male lizard models were less well camouflaged against their habitat and more likely to fall prey to bird attacks.

Marshall, lead author of the study, explains: “we wanted to get to the origins of colour evolution; to find out what is causing colour variation between these lizards. We wanted to know whether natural selection favours camouflage, and whether the conflicting need to have bright sexual signals might impair its effectiveness.

“It has previously been assumed that conspicuous male colours are costly to survival, but this hasn’t been tested before among these specific lizards living on different islands, and in general rarely in a way that takes into account the particular sensitivities of avian vision.”

Birds see the world differently from you or I: they are able to see ultraviolet (UV) light whereas we cannot, which means they perceive colour (and camouflage) in a very different way. To test whether the males really are more visible to feathered predators, the researchers had to develop clay models that accurately replicated the lizards’ colour to a bird’s eye.

Using visual modelling, Marshall and her colleagues painstakingly tested around 300 colour variations to find ones that matched the male and female colours in order to make the 600 clay lizards used in the study.

Marshall comments: “it was important to get a clay colour that would be indistinguishable from a real lizard to a bird’s eyes: we even tried using a paint colour chart, but they all reflected too much UV. To us the models may not look like very good likenesses, but to a bird the models should have looked the same colour as the real lizards.”

Marshall and her field assistant, Kate Philpot, placed the male and female lizard models in ten sites on each of the two islands and checked them every 24 hours over five days to see which had been attacked by birds.

“The models that had been attacked showed signs of beak marks, particularly around the head, and some had been decapitated,” explains Marshall. “We even found a few heads in different fields to the bodies.”

“The fact that the birds focused their attacks on the heads of the models also shows us that they perceived them as real lizards because that is how they would attack real prey,” she adds.

At the end of the study, the researchers found that the models with male colouration had been attacked more than the models with female colouration.

Marshall and the team also tested how conspicuous the models were against their real backgrounds using further modelling of avian vision, and found that the male models were less camouflaged than the females.

“In females, selection seems to have favoured better camouflage to avoid attack from avian predators. But in males, being bright and conspicuous also appears to be important even though this heightens the risk of being spotted by birds,” says Marshall.

However, it is not entirely a tale of woe for the male Aegean wall lizard. Despite being attacked more than the females by predatory birds, 83% of the male lizard models survived over the course of the five-day experiment. Marshall explains that this may indicate that males have colour adaptations that balance the contradictory needs to attract a mate and to avoid becoming lunch.

“In past work we’ve found these lizards have evolved bright colours on their sides, which are more visible to other lizards on the ground than to birds hunting from above,” explains Marshall. “The visual system of lizards is different again from birds, such as through increased sensitivity to UV, so the colour on their backs is more obvious to other lizards than to birds. Such selective “tuning” of colours to the eyes of different observers might provide at least some camouflage against dangerous predators that sneakily eavesdrop on the bright signals of their prey.”

“With these models we were only able to replicate the overall colour of the lizards rather than their patterns, so it would be interesting to investigate further whether these patterns affect the survival rates of lizard models,” she adds. “It would also be great to apply this type of experiment to other questions, such as how different environments affect the amount of predation that prey animals experience.”

Reference: Marshall, K et al. “Conspicuous male coloration impairs survival against avian predators in Aegean wall lizards, Podarcis erhardii” Ecology and Evolution (September 2015). DOI: http://onlinelibrary.wiley.com/doi/10.1002/ece3.1650/full

The research was enabled by funding from the Biotechnology and Biological Sciences Research Council, the British Herpetological Society, the Cambridge Philosophical Society, and Magdalene College, Cambridge.

Inset images: Tetrahedral plot of avian vision (Kate Marshall et al); Models showing signs of bird attack (Kate Marshall et al); Males, females and their corresponding models (Kate Marshall et al).

Increased greenhouse gas emissions from the release of carbon dioxide and methane contained in the Arctic permafrost could result in $43 trillion in additional economic damage by the end of the next century, according to researchers from the University of Cambridge and the University of Colorado.

In a letter published today (21 September) in the journal Nature Climate Change, the researchers have for the first time modelled the economic impact caused by melting permafrost in the Arctic to the end of the twenty-second century, on top of the damage already predicted by climate and economic models.

The Arctic is warming at a rate which is twice the global average, due to anthropogenic, or human-caused, greenhouse gas emissions. If emissions continue to rise at their current rates, Arctic warming will lead to the widespread thawing of permafrost and the release of hundreds of billions of tonnes of methane and CO₂ – about 1,700 gigatonnes of carbon are held in permafrost soils in the form of frozen organic matter.

Rising emissions will result in both economic and non-economic impacts, as well as a higher chance of catastrophic events, such as the melting of the Greenland and West Antarctic ice sheets, increased flooding and extreme weather. Economic impacts directly affect a country’s gross domestic product (GDP), such as the loss of agricultural output and the additional cost of air conditioning, while non-economic impacts include effects on human health and ecosystems.

The researchers’ models predict $43 trillion in economic damage could be caused by the release of these greenhouse gases, an amount equivalent to more than half the current annual output of the global economy. This brings the total predicted impact of climate change by 2200 to $369 trillion, up from $326 trillion – an increase of 13 percent.

“These results show just how much we need urgent action to slow the melting of the permafrost in order to minimise the scale of the release of greenhouse gases,” said co-author Dr Chris Hope from the Cambridge Judge Business School.

Hope’s calculations were conducted in collaboration with Kevin Schaefer of the National Snow and Ice Data Center at the University of Colorado.

Hope and Schaefer used the PAGE09 (Policy Analysis of the Greenhouse Effect) integrated assessment model to measure the economic impact of permafrost thawing on top of previous calculations of the climate change costs of business-as-usual greenhouse gas emissions from the Intergovernmental Panel on Climate Change (IPCC).

“We want to use these models to help us make better decisions – linking scientific and economic models together is a way to help us do that,” said Hope. “We need to estimate how much it will cost if we do nothing, how much it will cost if we do something, and how much we need to spend to cut back greenhouse gases.”

The researchers say that if an aggressive strategy to reduce emissions from thawing permafrost is adopted, it could reduce the impact by as much as $37 trillion.

Reference:
Hope, C. and Schaefer, K. ‘Economic impacts of carbon dioxide and methane released from thawing permafrost’. Nature Climate Change (2015). DOI: 10.1038/nclimate2807

Analysis of the London Tube strike in February 2014 has found that despite the inconvenience to tens of thousands of people, the strike actually produced a net economic benefit, due to the number of people who found more efficient ways to get to work.

The researchers, from the University of Cambridge and the University of Oxford, examined 20 days’ worth of anonymised Oyster card data, containing more than 200 million data points, in order to see how individual Tube journeys changed during the strike. Since this particular strike only resulted in a partial closure of the Tube network and not all commuters were affected by the strike, a direct comparison was possible. The data enabled the researchers to see whether people chose to go back to their normal commute once the strike was over, or if they found a more efficient route and decided to switch.

The researchers found that of the regular commuters affected by the strike, either because certain stations were closed or because travel times were considerably different, a significant fraction – about one in 20 – decided to stick with their new route once the strike was over.

While the proportion of individuals who ended up changing their routes may sound small, the researchers found that the strike actually ended up producing a net economic benefit. By performing a cost-benefit analysis of the amount of time saved by those who changed their daily commute, the researchers found that the amount of time saved in the longer term actually outweighed the time lost by commuters during the strike. An Oxford working paper of their findings is published online today.

The London Tube map itself may have been a reason why many commuters did not find their optimal journey before the strike. In many parts of London, the actual distances between stations are distorted on the iconic map. By digitising the Tube map and comparing it to the actual distances between stations, the researchers found that those commuters living in, or travelling to, parts of London where distortion is greatest were more likely to have learned from the strike and found a more efficient route.

Additionally, since different Tube lines travel at different speeds, those commuters who had been travelling on one of the slower lines were also more likely to switch routes once the strike was over.

“One of the things we’re looking at is whether consumers usually make the best decision, but it’s never been empirically tested using a large consumer dataset such as this one,” said co-author Dr Ferninand Rauch from Oxford’s Department of Economics. “Our findings illustrate that people might get stuck with suboptimal decisions because they don’t experiment enough.”

According to the authors, being forced to alter a routine, whether that’s due to a Tube strike or government regulation, can often lead to net benefits, as people or corporations are forced to innovate. In economics, this is known as the Porter hypothesis.

“For the small fraction of commuters who found a better route, when multiplied over a longer period of time, the benefit to them actually outweighs the inconvenience suffered by many more,” said co-author Dr Shaun Larcom of Cambridge’s Department of Land Economy. “The net gains came from the disruption itself.”

“Given that a significant fraction of commuters on the London underground failed to find their optimal route until they were forced to experiment, perhaps we should not be too frustrated that we can’t always get what we want, or that others sometimes take decisions for us,” said co-author Dr Tim Willems, also from Oxford’s Department of Economics. “If we behave anything like London commuters and experiment too little, hitting such constraints may very well be to our long-term advantage.”

Reference:
Larcom, Shaun, Ferdinand Rauch and Tim Willems (2015), “The Benefits of Forced Experimentation: Striking Evidence from the London Underground Network”, University of Oxford Working Paper. 

Spironolactone, one of a range of drugs given according to doctors’ preference to patients with resistant hypertension (high blood pressure that doesn’t respond to a standard drug treatment), is in fact “outstandingly superior” to the alternatives, researchers have found. They recommend it should now be the first choice for such patients, and say that – for most – this well-known but under-valued drug will bring their condition fully under control.

The discovery could have a profound impact globally, since hypertension, a major contributor to stroke and heart disease, is so common, affecting as many as one in three adults in some countries. It challenges what the authors describe as “a growing perception” that severe hypertension was beyond the control of existing drug treatments, and gives more clues into what causes the condition.

The latest research, published today in the Lancet to coincide with their presentation to the British Hypertension Society, emerged from the PATHWAY-2 trial, part of the PATHWAY programme of trials in hypertension funded by the British Heart Foundation and led by Professor Morris Brown, professor of clinical pharmacology at Cambridge University and a Fellow of Gonville & Caius College.

The findings are drawn from what authors Brown and Professor Bryan Williams of University College London describe as an experimental “shoot-out” between three different drugs used by doctors for years to treat patients if the standard initial cocktail of three hypertension drugs do  not work.

Spironolactone ‘slugged it out’ against a betablocker (bisoprolol) and an alpha-blocker (doxazosin) in the trial, which took six years and involved 314 patients in 14 different centres.

The patients all suffered from resistant high blood pressure that had not responded to the standard treatment for hypertension: a combination of three drugs (an ACE-inhibitor (or angiotensin-receptor blocker), a calcium channel blocker and a thiazide-type diuretic). They continued with this basic combination thoughout, but each of the three trial drugs – and a placebo – was added one at a time, in random order, for 12 weeks each.

In what is known as a “double blind” trial, neither the patients nor the researchers knew which patient was taking which drug when. In a pioneering step, the study also used patients’ own blood pressure readings taken at home to minimise so-called “white coat syndrome”, in which the stress of being in a clinic causes blood pressure to rise artificially.

Once the resulting data had been analysed, it emerged that almost three quarters of patients in the trial saw a major improvement in blood pressure on spironolactone, with almost 60% hitting a particularly stringent measure of blood pressure control. Of the three drugs trialled, spironolactone was the best at lowering blood pressure in 60% of patients, whereas bisoprolol and doxazosin were the best drug in only 17% and 18% respectively.

“Spironolactone annihilated the opposition,” said Brown. “Most patients came right down to normal blood pressure while taking it.”

He added: “This is an old drug which has been around for a couple of generations that has resurfaced and is almost a wonder drug for this group of patients. In future it will stimulate us to look for these patients at a much earlier stage so we can treat and maybe even cure them before resistant hypertension occurs.”

Doctors appear to have been wary of giving patients spironolactone because it raises the level of potassium in the body. But the study revealed the rise to be only marginal and not dangerous.

The causes of resistant of hypertension are still poorly understood, but one theory is that the condition could be the result of sodium retention: too much salt in the body.

Spironolactone is a diuretic and helps the body get rid of salt. In the trial, it worked even better than average on patients whom tests showed had high salt levels. Brown said the findings appeared to confirm that, in most patients with resistant hypertension, excessive salt was the problem, probably caused by too much of the adrenal hormone aldosterone.

Instead of seeing the treatment-resistant form of high blood pressure as simply the result of having the condition for a long time or of poor treatment, it should be regarded as a different sub-group of hypertension which would need different investigations and treatments, Brown said.

An artificial pancreas given to children and adults with type 1 diabetes going about their daily lives has been proven to work for 12 weeks – meaning the technology, developed at the University of Cambridge, can now offer a whole school term of extra freedom for children with the condition.

Artificial pancreas trials for people at home, work and school have previously been limited to short periods of time. But a study, published today in the New England Journal of Medicine, saw the technology safely provide three whole months of use, bringing us closer to the day when the wearable, smartphone-like device can be made available to patients.

The lives of the 400,000 UK people with type 1 diabetes currently involves a relentless balancing act of controlling their blood glucose levels by finger-prick blood tests and taking insulin via injections or a pump. But the artificial pancreas sees tight blood glucose control achieved automatically.

This latest Cambridge study showed the artificial pancreas significantly improved control of blood glucose levels among participants – lessening their risk of hypoglycaemia. Known as ‘having a hypo,’ hypoglycaemia is a drop in blood glucose levels that can be highly dangerous and is what people with type 1 diabetes hate most.

Susan Walls is mother to Daniel Walls, a 12-year-old with type 1 diabetes who has taken part in the trial. She said: “Daniel goes back to school this month after the summer holidays – so it’s a perfect time to hear this wonderful news that the artificial pancreas is proving reliable, offering a whole school term of support.

“The artificial pancreas could change my son’s life, and the lives of so many others. Daniel has absolutely no hypoglycaemia awareness at night. His blood glucose levels could be very low and he wouldn’t wake up. The artificial pancreas could give me the peace of mind that I’ve been missing.”

“The data clearly demonstrate the benefits of the artificial pancreas when used over several months,” said Dr Roman Hovorka, Director of Research at the University’s Metabolic Research Laboratories, who developed the artificial pancreas. “We have seen improved glucose control and reduced risk of unwanted low glucose levels.”

The Cambridge study is being funded by JDRF, the type 1 diabetes charity. Karen Addington, Chief Executive of JDRF, said: “JDRF launched its goal of perfecting the artificial pancreas in 2006. These results today show that we are thrillingly close to what will be a breakthrough in medical science.”

Reference:
Thabit, Hood et al. ‘Free-living Home Use of an Artificial Beta Cell in Type 1 Diabetes.’ New England Journal of Medicine (2015). DOI: 10.1056/NEJMoa1509351

Adapted from a JDRF press release.

At a time of global focus on refugee issues due to the war in Syria and other displacement, new research from the University of Cambridge calls for policymakers to foster entrepreneurship at refugee camps to help fill an ‘institutional void’ that leads to despair, boredom and crime.

Although most refugee camps are initially set up to provide supposedly “temporary” safety for people uprooted by war, natural disaster or other events, the reality is that many forcibly displaced people spend 20 years or more in exile.

A paper from Cambridge researchers calls on governments and other policymakers to promote refugee-camp entrepreneurship in order to provide an economic and psychological boost to displaced people.

“Refugee camp entrepreneurs reduce aid dependency and in so doing help to give life meaning for, and confer dignity on, the entrepreneurs,” says the paper, by Marlen de la Chaux, a PhD student at the Cambridge Judge Business School, and Helen Haugh, Senior Lecturer in Community Enterprise at Cambridge Judge. Marlen is a Gates Cambridge Scholar.

While such camps are created on the assumption they will be temporary in response to a passing emergency, such displacement is in fact often protracted – so “the rules of the game concerning temporary institutions do not reflect the reality of life in the camp,” the paper says.

The paper – entitled “Entrepreneurship and Innovation: How Institutional Voids Shape Economic Opportunities in Refugee Camps” – was presented by the authors at this summer’s 75th Annual Meeting of the Academy of Management in Vancouver, Canada.

The researchers identify three institutional barriers to refugee camp entrepreneurship: a lack of functioning markets, inefficient legal and political systems, and poor infrastructure.

This presents a number of opportunities for policymakers to boost entrepreneurship opportunities, including urban planning techniques to design useful infrastructure because long-term refugee camps tend to resemble small cities rather than transient settlements.

In addition, cash-based aid programmes and partnerships between refugee camp organisers and micro-lending institutions can provide seed capital to refugee camp ventures; innovation hubs such as those recently established in Nairobi, Kenya, can help provide access to business advice and seed capital; and the host country can create employment opportunities within the refugee camp by outsourcing some tasks to refugees.

“As the number of forcibly displaced increases, the urgency to find solutions to redress the negative aspects of life in a refugee camp for those in protracted exile also rises,” the paper says. Enlightened policies to boost refugee-camp entrepreneurship “may also make a positive contribution to the economy of the host country and in so doing help to reduce the local resentment experienced by those living in camps.”

Adapted from an article originally published on the Cambridge Judge Business School website.

Scientists have identified an ingeniously elegant brain circuit consisting of just five nerve cells that allows female crickets to automatically identify the chirps of males from the same species through the rhythmic pulses hidden within the mating call.

The circuit uses a time delay mechanism to match the gaps between pulses in a species-specific chirp – gaps of just few milliseconds. The circuit delays a pulse by the exact between-pulse gap, so that, if it coincides with the next pulse coming in, the same species signal is confirmed.

It’s one of the first times a brain circuit consisting of individual neurons that identifies an acoustic rhythm has been characterised. The results are reported today (11 September) in the journal Science Advances.

Using tiny electrodes, scientists from Cambridge University’s Department of Zoology explored the brain of female crickets for individual auditory neurons responding to digitally-manipulated cricket chirps (even a relatively simple organism such as a cricket still has a brain containing up to a million neurons).

Once located, the nerve cells were stained with fluorescent dye. By monitoring how each neuron responded to the sound pulses of the cricket chirps, scientists were able to work out the sequence the neurons fired in, enabling them to unpick the time delay logic of the circuit.

Sound processing starts in hearing organs, but the temporal, rhythmic features of sound signals – vital to all acoustic communication from birdsong to spoken language – are processed in the central auditory system of the brain.

Scientists say that the simple, time-coded neural network discovered in the brain of crickets may be an example of fundamental neural circuitry that identifies sound rhythms and patterns, and could be the basis for “complex and elaborate neuronal systems” in vertebrates.

“Compared to our complex language, crickets only have a few songs which they have to recognise and process, so, by looking at their much simpler brain, we aim to understand how neurons process sound signals,” said senior author Dr Berthold Hedwig.

Like in Morse code, contained within each cricket chirp are several pulses, interspersed by gaps of a few milliseconds. It’s the varying length of the gaps between pulses that is each species’ unique rhythm.

It is this ‘Morse code’ that gets read by the five-neuron circuit in the female brain.

Crickets’ ears are located on their front legs. On hearing a sound like a chirp, nerve cells respond and carry the information to the thoracic segment, and on to the brain.

Once there, the auditory circuit splits and sends the information into two branches:

One branch (consisting of two neurons) acts as a delay line, holding up the processing of the signal by the same amount of time as the interval between pulses – a mechanism specific to a cricket species’ chirp. The other branch sends the signal straight through to a ‘coincidence detector’ neuron.

When a second pulse comes in, it too is split, and part of the signal goes straight through to the coincidence detector. If the second pulse and the delayed signal from the first pulse ‘coincide’ within the detector neuron, then the circuit has a match for the pulse time-code within the chirp of their species, and a final output neuron fires up, when the female listens to the correct sound pattern.

“Once the circuit has a second pulse, it can define the rhythm. The first pulse is initial excitation; the second pulse is then superimposed with the delayed part of the first. The output neuron only produces a strong response if the pulses collide at the coincidence detector, meaning the timing is locked in, and the mating call is a species match,” said Hedwig.

“With hindsight, I would say it’s impossible to make the circuitry any simpler – it’s the minimum number of elements that are required to do the processing. That’s the beauty of nature, it comes up with the most simple and elegant ways of dealing with and processing information,” he said.

To find the most effective sound pattern, the scientists digitally manipulated the natural pulse patterns and played the various patterns to female crickets mounted atop a trackball inside an acoustic chamber containing precisely located speakers.

If a particular rhythm of pulses triggered the female to set off in the direction of that speaker, the trackball recorded reaction times and direction.

Once they had honed the pulse patterns, the team played them to female crickets in modified mini-chambers with opened-up heads and brains exposed for the experiments.

Microelectrodes allowed them to record the key auditory neurons (“it takes a couple of hours to find the right neuron in a cricket brain”), tag and dye them, and piece together the neural circuitry that reads rhythmic pulses occurring at intervals of few milliseconds in male cricket chirps.

Added Hedwig: “Through this series of experiments we have identified a delay mechanism within a neuronal circuit for auditory processing – something that was first hypothesised over 25 years ago. This time delay circuitry could be quite fundamental as an example for other types of neuronal processing in other, perhaps much larger, brains as well.”

The research was funded by the Biotechnology and Biological Sciences Research Council (BBSRC).

Reference:
Stefan Schöneich, Konstantinos Kostarakos, Berthold Hedwig. An auditory feature detection circuit for sound pattern recognition. Science Advances (2015). DOI: 10.1126/sciadv.1500325

A new study conducted in collaboration with Facebook using anonymised data from the social networking site shows a correlation between people’s social and financial status, and the levels of internationalism in their friendship networks – with those from higher social classes around the world having fewer friends outside of their own country.

Despite the fact that, arguably, people from higher social classes should be better positioned to travel and meet people from different countries, researchers found that, when it comes to friendship networks, people from those groups had lower levels of internationalism and made more friends domestically than abroad.

Researchers say that their results are in line with what’s known as the ‘restricting social class’ hypothesis: that high-social class individuals have greater resources, and therefore depend less on others – with the wealthy tending to be less socially engaged, particularly with those from groups other than their own, as a result.

The research team, from the Prosociality and Well-Being Lab in the University of Cambridge’s Department of Psychology, conducted two studies – one local and one global, with the global study using a dataset of billions of Facebook friendships – and the results from both supported the idea of restricting social class.

However, the researchers say the fact that those of lower social status tend to have more international connections demonstrates how low-social class people “may actually stand to benefit most from a highly international and globalised social world”.

“The findings point to the possibility that the wealthy stay more in their own social bubble, but this is unlikely to be ultimately beneficial. If you are not engaging internationally then you will miss out on that international resource – that flow of new ideas and information,” said co-author Dr Aleksandr Spectre, who heads up the lab.

“The results could also be highlighting a mechanism of how the modern era might facilitate a closing of the inequality gap, as those from lower social classes take advantage of platforms like Facebook to increase their social capital beyond national borders,” he said.

For the first study, the ‘local’, the team recruited 857 people in the United States and asked them to self-report their perceived social status (from working to upper class on a numerical scale), as well as an objective indicator in the form of annual household income. The volunteers also provided researchers access to their Facebook networks.

The results from the first study indicated that low-social class people have nearly 50% more international friends than high-social class people.

For the second study, the ‘global’, the team approached Facebook directly, who provided data on every friendship formed over the network in every country in the world at the national aggregate level for 2011. All data was anonymous. The dataset included over 57 billion friendships.

The research team quantified social class on a national level based on each country’s economic standing by using gross domestic product (GDP) per capita data for 2011 as published by the World Bank.

After controlling for as many variables as they were able, the researchers again found a negative correlation between social class – this time on a national level – and the percentage of Facebook friends from other countries. For people from low-social class countries, 35% of their friendships on average were international, compared to 28% average in high-social class countries.

The findings from the two studies provide support for the restricting social class hypothesis on both a local and a global level, say the researchers. The results are contained in a new paper, published in the journal Personality and Individual Differences.

“Previous research by others has highlighted the value of developing weak ties to people in distant social circles, because they offer access to resources not likely to be found in one’s immediate circle. I find it encouraging that low-social class people tend to have greater access to these resources on account of having more international friendships,” said co-author Maurice Yearwood.

“From a methodological perspective, this combination of micro and macro starts to build a very interesting initial story. These are just correlations at the moment, but it’s a fascinating start for this type of research going forward,” Yearwood said.

Spectre says that the high levels of Facebook usage and sheer size of the network makes it a “pretty good proxy for your social environment”. “The vast majority of Facebook friendships are ones where people have met in person and engaged with each other, a lot of the properties you find in Facebook friendship networks will strongly mirror everyday life,” he said.

“We are entering an era with big data and social media where we can start to ask really big questions and gain answers to them in a way we just couldn’t do before. I think this research is a good example of that, I don’t know how we could even have attempted this work 10 years ago,” Spectre said.

The latest work is the first output of ongoing research collaborations between Spectre’s lab in Cambridge and Facebook, a company he commends for its “scientific spirit”.  “Having the opportunity to work with companies like Facebook, Twitter, Microsoft and Google should be something that’s hugely exciting to the academic community,” he said.

Reference:
Yearwood, M. H., Cuddy, A., Lamba, N., Youyou, W., van der Lowe, I., Piff, P., Gronin, C., Fleming, P., Simon-Thomas, E., Keltner, D., & Spectre, A. (2015). On wealth and the diversity of friendships: High social class people around the world have fewer international friends. Personality and Individual Differences, 87, 224-229. DOI: doi:10.1016/j.paid.2015.07.040

The study, which compares spoken English today with recordings from the 1990s, allows researchers at Cambridge University Press and Lancaster University to examine how the language we use indicates our changing attitudes to education.

They found that the topic of education is far more salient in conversations now, with the word cropping up 42 times per million words, compared with only 26 times per million in the 1990s dataset.

As well as talking about education more, there has also been a noticeable shift in the terms we use to describe it. Twenty years ago, the public used fact-based terms to talk about education, most often describing it as either full-time, or part-time.

Today, however, we’re more likely to use evaluative language about the standards of education and say that it’s good, bad or great. This could be due to the rise in the formal assessments of schools, for example, with the establishment of the Office for Standards in Education, Children’s Services and Skills (OFSTED) in 1992. Indeed, Ofsted itself has made its debut as a verb in recent times, with the arrival of discussions on what it means for a school to be Ofsteded.

Dr Claire Dembry, Senior Language Research Manager at Cambridge University Press said: “It’s fascinating to find out that, not only do we talk about education twice as much as we used to, but also that we are more concerned about the quality. It’s great that we have these data sets to be able to find out these insights; without them we wouldn’t be able to research how the language we use is changing, nor the topics we talk about most.”

The research findings also indicate that we’re now expecting to get more out of our education than we used to. We’ve started talking about qualifications twice as much as we did in the 1990s, GCSEs five times as much and A levels 1.4 times as much.

Meanwhile, use of the word university has tripled. This is perhaps not surprising, as the proportion of young people going to university doubled between 1995 and 2008, going from 20 per cent to almost 40 per cent.

When the original data was collected in the 1990s, university fees had yet to be introduced, and so it is unsurprising that the terms university fees and tuition fees did not appear in the findings. However the recent data shows these terms to each occur roughly once per million words, as we’ve begun to talk about university in more commercialised terms.

However, while teachers may be happy to hear that education is of growing concern to the British public, it won’t come as good news to them that the adjective underpaid is most closely associated with their job.

These are only the initial findings from the first two million words of the project, named the ‘Spoken British National Corpus 2014,’ which is still seeking recorded submissions.

Professor Tony McEnery, from the ESRC Centre for Corpus Approaches to Social Sciences (CASS) at Lancaster University, said: “We need to gather hundreds, if not thousands, of conversations to create a full spoken corpus so we can continue to analyse the way language has changed over the last 20 years.

“This is an ambitious project and we are calling for people to send us MP3 files of their everyday, informal conversations in exchange for a small payment to help me and my team to delve deeper into spoken language and to shed more light on the way our spoken language changes over time.”

People who wish to submit recordings to the research team should visit: http://languageresearch.cambridge.org/index.php/spoken-british-national-…

Using a new metric, ‘GDP @Risk’, the ‘Catastronomics’ techniques developed by researchers at the University of Cambridge reveal that major threats to the world’s most important cities could reduce economic output by some $4.56 trillion, equivalent to 1.2 per cent of the total GDP forecast to be generated by these cities in the next decade.

The techniques, developed by researchers at the Cambridge Centre for Risk Studies, provide the data and risk analysis for the Lloyd’s City Risk Index 2015-2025, which was launched last week.

“GDP @Risk makes it possible to combine and compare a very wide range of threats, including those that are disruptive and costly, such as market collapse, in addition to destructive and deadly natural catastrophes, and measure their impact on economic output,” said Professor Daniel Ralph, Academic Director of Cambridge Centre for Risk Studies, which is based at the Cambridge Judge Business School. “This 1.2 per cent is the estimated ‘catastrophe burden’ on the world’s economy – without this, the growth of global GDP, currently running at around three per cent a year, would be significantly higher.”

Lloyd’s City Risk Index encompasses 301 of the world’s leading cities, selected by economic, business and political importance. These cities are responsible for over half of global GDP today, and an estimated two-thirds of the world’s economic output by 2025.

The analysis considers 18 different threats from manmade events, such as market crashes and technological catastrophes, to natural disasters to these urban centres. It examines the likelihood and severity of disruption of the output from the city as an economic engine, rather than metrics of physical destruction or repair cost loss – which is the traditional focus of conventional catastrophe models.

The Centre’s analysis reflects the typologies of different economic activities in each city. The GDP growth history, demographics and other data are used to derive GDP projections out to 2025 for each city. GDP @Risk is a long run average: the economic loss caused by ‘all’ catastrophes that might occur in an average decade, baselined against economic performance between 2015 and 2025.

Professor Ralph added: “A framework to quantify the average damage caused by a Pandora’s box of all ills – a ‘universal’ set of catastrophes – can be used to calibrate the value of investing in resilience. This is what the GDP @Risk metric for 300 World Cities attempts to provide. We believe that it is possible to estimate the cost to a business, city, region or the global economy, from all catastrophic shocks. Such holistic approaches are an antidote to risk management that reacts to threats taken from yesterday’s news headlines. Our simple methodology suggests that between 10 per cent and 25 per cent of GDP @Risk could be recovered, in principle, by improving resilience of all cities.”

Adapted from an article originally published on the Cambridge Judge Business School website.

Astronomers from the University of Cambridge have developed a new, highly accurate method of measuring the distances between stars, which could be used to measure the size of the galaxy, enabling greater understanding of how it evolved.

Using a technique which searches out stellar ‘twins’, the researchers have been able to measure distances between stars with far greater precision than is possible using typical model-dependent methods. The technique could be a valuable complement to the Gaia satellite – which is creating a three-dimensional map of the sky over five years – and could aid in the understanding of fundamental astrophysical processes at work in the furthest reaches of our galaxy. Details of the new technique are published in the Monthly Notices of the Royal Astronomical Society.

“Determining distances is a key problem in astronomy, because unless we know how far away a star or group of stars is, it is impossible to know the size of the galaxy or understand how it formed and evolved,” said Dr Paula Jofre Pfeil of Cambridge’s Institute of Astronomy, the paper’s lead author. “Every time we make an accurate distance measurement, we take another step on the cosmic distance ladder.”

The best way to directly measure a star’s distance is by an effect known as parallax, which is the apparent displacement of an object when viewed along two different lines of sight – for example, if you hold out your hand in front of you and look at it with your left eye closed and then with your right eye closed, your hand will appear to move against the background. The same effect can be used to calculate the distance to stars, by measuring the apparent motion of a nearby star compared to more distant background stars. By measuring the angle of inclination between the two observations, astronomers can use the parallax to determine the distance to a particular star.

However, the parallax method can only be applied for stars which are reasonably close to us, since beyond distances of 1600 light years, the angles of inclination are too small to be measured by the Hipparcos satellite, a precursor to Gaia. Consequently, of the 100 billion stars in the Milky Way, we have accurate measurements for just 100,000.

Gaia will be able to measure the angles of inclination with far greater precision than ever before, for stars up to 30,000 light years away. Scientists will soon have precise distance measurements for the one billion stars that Gaia is mapping – but that’s still only one percent of the stars in the Milky Way.

For even more distant stars, astronomers will still need to rely on models which look at a star’s temperature, surface gravity and chemical composition, and use the information from the resulting spectrum, together with an evolutionary model, to infer its intrinsic brightness and to determine its distance. However, these models can be off by as much as 30 percent. “Using a model also means using a number of simplifying assumptions – like for example assuming stars don’t rotate, which of course they do,” said Dr Thomas Mädler, one of the study’s co-authors. “Therefore stellar distances obtained by such indirect methods should be taken with a pinch of salt.”

The Cambridge researchers have developed a novel method to determine distances between stars by relying on stellar ‘twins’: two stars with identical spectra. Using a set of around 600 stars for which high-resolution spectra are available, the researchers found 175 pairs of twins. For each set of twins, a parallax measurement was available for one of the stars.

The researchers found that the difference of the distances of the twin stars is directly related to the difference in their apparent brightness in the sky, meaning that distances can be accurately measured without having to rely on models. Their method showed just an eight percent difference with known parallax measurements, and the accuracy does not decrease when measuring more distant stars.

“It’s a remarkably simple idea – so simple that it’s hard to believe no one thought of it before,” said Jofre Pfeil. “The further away a star is, the fainter it appears in the sky, and so if two stars have identical spectra, we can use the difference in brightness to calculate the distance.”

Since a utilised spectrum for a single star contains as many as 280,000 data points, comparing entire spectra for different stars would be both time and data-consuming, so the researchers chose just 400 spectral lines to make their comparisons. These particular lines are those which give the most distinguishing information about the star – similar to comparing photographs of individuals and looking at a single defining characteristic to tell them apart.

The next step for the researchers is to compile a ‘catalogue’ of stars for which accurate distances are available, and then search for twins among other stellar catalogues for which no distances are available. While only looking at stars which have twins restricts the method somewhat, thanks to the new generation of high-powered telescopes, high-resolution spectra are available for millions of stars. With even more powerful telescopes under development, spectra may soon be available for stars which are beyond even the reach of Gaia, so the researchers say their method is a powerful complement to Gaia.

“This method provides a robust way to extend the crucially-important cosmic distance ladder in a new special way,” said Professor Gerry Gilmore, the Principal Investigator for UK involvement in the Gaia mission. “It has the promise to become extremely important as new very large telescopes are under construction, allowing the necessary detailed observations of stars at large distances in galaxies far from our Milky Way, building on our local detailed studies from Gaia.”

The research was funded by the European Research Council.

Reference:
Jofré, P. et. al. Climbing the cosmic ladder with stellar twins. Monthly Notices of the Royal Astronomical Society (2015). DOI: 10.1093/mnras/stv1724. 

A team of scientists has successfully measured particles of light being “squeezed”, in an experiment that had been written off in physics textbooks as impossible to observe.

Squeezing is a strange phenomenon of quantum physics. It creates a very specific form of light which is “low-noise” and is potentially useful in technology designed to pick up faint signals, such as the detection of gravitational waves.

The standard approach to squeezing light involves firing an intense laser beam at a material, usually a non-linear crystal, which produces the desired effect.

For more than 30 years, however, a theory has existed about another possible technique. This involves exciting a single atom with just a tiny amount of light. The theory states that the light scattered by this atom should, similarly, be squeezed.

Unfortunately, although the mathematical basis for this method – known as squeezing of resonance fluorescence – was drawn up in 1981, the experiment to observe it was so difficult that one established quantum physics textbook despairingly concludes: “It seems hopeless to measure it”.

So it has proven – until now. In the journal Nature, a team of physicists report that they have successfully demonstrated the squeezing of individual light particles, or photons, using an artificially constructed atom, known as a semiconductor quantum dot. Thanks to the enhanced optical properties of this system and the technique used to make the measurements, they were able to observe the light as it was scattered, and proved that it had indeed been squeezed.

Professor Mete Atature, from the Cavendish Laboratory, Department of Physics, and a Fellow of St John’s College at the University of Cambridge, led the research. He said: “It’s one of those cases of a fundamental question that theorists came up with, but which, after years of trying, people basically concluded it is impossible to see for real – if it’s there at all.”

“We managed to do it because we now have artificial atoms with optical properties that are superior to natural atoms. That meant we were able to reach the necessary conditions to observe this fundamental property of photons and prove that this odd phenomenon of squeezing really exists at the level of a single photon. It’s a very bizarre effect that goes completely against our senses and expectations about what photons should do.”

Like a lot of quantum physics, the principles behind squeezing light involve some mind-boggling concepts.

It begins with the fact that wherever there are light particles, there are also associated electromagnetic fluctuations. This is a sort of static which scientists refer to as “noise”. Typically, the more intense light gets, the higher the noise. Dim the light, and the noise goes down.

But strangely, at a very fine quantum level, the picture changes. Even in a situation where there is no light, electromagnetic noise still exists. These are called vacuum fluctuations. While classical physics tells us that in the absence of a light source we will be in perfect darkness, quantum mechanics tells us that there is always some of this ambient fluctuation.

“If you look at a flat surface, it seems smooth and flat, but we know that if you really zoom in to a super-fine level, it probably isn’t perfectly smooth at all,” Atature said. “The same thing is happening with vacuum fluctuations. Once you get into the quantum world, you start to get this fine print. It looks like there are zero photons present, but actually there is just a tiny bit more than nothing.”

Importantly, these vacuum fluctuations are always present and provide a base limit to the noise of a light field. Even lasers, the most perfect light source known, carry this level of fluctuating noise.

This is when things get stranger still, however, because, in the right quantum conditions, that base limit of noise can be lowered even further. This lower-than-nothing, or lower-than-vacuum, state is what physicists call squeezing.

In the Cambridge experiment, the researchers achieved this by shining a faint laser beam on to their artificial atom, the quantum dot. This excited the quantum dot and led to the emission of a stream of individual photons. Although normally, the noise associated with this photonic activity is greater than a vacuum state, when the dot was only excited weakly the noise associated with the light field actually dropped, becoming less than the supposed baseline of vacuum fluctuations.

Explaining why this happens involves some highly complex quantum physics. At its core, however, is a rule known as Heisenberg’s uncertainty principle. This states that in any situation in which a particle has two linked properties, only one can be measured and the other must be uncertain.

In the normal world of classical physics, this rule does not apply. If an object is moving, we can measure both its position and momentum, for example, to understand where it is going and how long it is likely to take getting there. The pair of properties – position and momentum – are linked.

In the strange world of quantum physics, however, the situation changes. Heisenberg states that only one part of a pair can ever be measured, and the other must remain uncertain.

In the Cambridge experiment, the researchers used that rule to their advantage, creating a tradeoff between what could be measured, and what could not. By scattering faint laser light from the quantum dot, the noise of part of the electromagnetic field was reduced to an extremely precise and low level, below the standard baseline of vacuum fluctuations. This was done at the expense of making other parts of the electromagnetic field less measurable, meaning that it became possible to create a level of noise that was lower-than-nothing, in keeping with Heisenberg’s uncertainty principle, and hence the laws of quantum physics.

Plotting the uncertainty with which fluctuations in the electromagnetic field could be measured on a graph creates a shape where the uncertainty of one part has been reduced, while the other has been extended. This creates a squashed-looking, or “squeezed” shape, hence the term, “squeezing” light.

Atature added that the main point of the study was simply to attempt to see this property of single photons, because it had never been seen before. “It’s just the same as wanting to look at Pluto in more detail or establishing that pentaquarks are out there,” he said. “Neither of those things has an obvious application right now, but the point is knowing more than we did before. We do this because we are curious and want to discover new things. That’s the essence of what science is all about.”

Additional image: The left diagram represents electromagnetic activity associated with light at what is technically its lowest possible level. On the right, part of the same field has been reduced to lower than is technically possible, at the expense of making another part of the field less measurable. This effect is called “squeezing” because of the shape it produces.

Reference: 
Schulte, CHH, et al. Quadrature squeezed photons from a two-level system. Nature (2015). DOI: 10.1038/nature14868. 

The Gaia satellite, which orbits the sun at a distance of 1.5million km from the earth, was launched by the European Space Agency in December 2013 with the aim of observing a billion stars and revolutionising our understanding of the Milky Way.

The unique mission is reliant on the work of Cambridge researchers who collect the vast quantities of data transmitted by Gaia to a data processing centre at the university, overseen by a team at the Institute of Astronomy.

Since the start of its observations in August 2014, Gaia has recorded 272 billion positional (or astrometric) measurements and 54.4 billion brightness (or photometric) data points.

Gaia surveys stars and many other astronomical objects as it spins, observing circular swathes of the sky. By repeatedly measuring the positions of the stars with extraordinary accuracy, Gaia can tease out their distances and motions throughout the Milky Way galaxy.

Dr Francesca de Angeli, lead scientist at the Cambridge data centre, said: “The huge Gaia photometric data flow is being processed successfully into scientific information at our processing centre and has already led to many exciting discoveries.”

The Gaia team have spent a busy year processing and analysing data, with the aim of developing enormous public catalogues of the positions, distances, motions and other properties of more than a billion stars. Because of the immense volumes of data and their complex nature, this requires a huge effort from expert scientists and software developers distributed across Europe, combined in Gaia’s Data Processing and Analysis Consortium (DPAC).

“The past twelve months have been very intense, but we are getting to grips with the data, and are looking forward to the next four years of operations,” said Timo Prusti, Gaia project scientist at ESA.

“We are just a year away from Gaia’s first scheduled data release, an intermediate catalogue planned for the summer of 2016. With the first year of data in our hands, we are now halfway to this milestone, and we’re able to present a few preliminary snapshots to show that the spacecraft is working well and that the data processing is on the right track.”

As Gaia has been conducting its repeated scans of the sky to measure the motions of stars, it has also been able to detect whether any of them have changed their brightness, and in doing so, has started to discover some very interesting astronomical objects.

Gaia has detected hundreds of transient sources so far, with a supernova being the very first on August 30, 2014. These detections are routinely shared with the community at large as soon as they are spotted in the form of ‘Science Alerts’, enabling rapid follow-up observations to be made using ground-based telescopes in order to determine their nature.

One transient source was seen undergoing a sudden and dramatic outburst that increased its brightness by a factor of five. It turned out that Gaia had discovered a so-called ‘cataclysmic variable’, a system of two stars in which one, a hot white dwarf, is devouring mass from a normal stellar companion, leading to outbursts of light as the material is swallowed. The system also turned out to be an eclipsing binary, in which the relatively larger normal star passes directly in front of the smaller, but brighter white dwarf, periodically obscuring the latter from view as seen from Earth.

Unusually, both stars in this system seem to have plenty of helium and little hydrogen. Gaia’s discovery data and follow-up observations may help astronomers to understand how the two stars lost their hydrogen.

Gaia has also discovered a multitude of stars whose brightness undergoes more regular changes over time. Many of these discoveries were made between July and August 2014, as Gaia performed many subsequent observations of a few patches of the sky.

Closer to home, Gaia has detected a wealth of asteroids, the small rocky bodies that populate our solar system, mainly between the orbits of Mars and Jupiter. Because they are relatively nearby and orbiting the Sun, asteroids appear to move against the stars in astronomical images, appearing in one snapshot of a given field, but not in images of the same field taken at later times.

Gaia scientists have developed special software to look for these ‘outliers’, matching them with the orbits of known asteroids in order to remove them from the data being used to study stars. But in turn, this information will be used to characterise known asteroids and to discover thousands of new ones.

Gerry Gilmore, Professor of Experimental Philosophy, and the Gaia UK Principal Investigator, said: “The early science from Gaia is already supporting major education activity involving UK school children and amateur astronomers across Europe and has established the huge discovery potential of Gaia’s data.

“We are entering a new era of big-data astrophysics, with a revolution in our knowledge of what we see in the sky. We are moving beyond just seeing to knowing about the galaxy in which we live.”