̽��ֱ�� of Cambridge - information

Opinion: How dangerous is burnt toast?

fpjl2 — Mon, 23 Jan 2017 08:53:32 +0000

̽��ֱ��Food Standards Agency (FSA) today launched its Go for Gold campaign, encouraging us not to burn our roast or fried vegetables and keep our oven chips at a nice golden colour. ̽��ֱ��idea is to reduce people’s intake of acrylamide, a chemical that is “created when many foods, particularly starchy foods like potatoes and bread, are cooked for long periods at high temperatures, such as when baking, frying, grilling, toasting and roasting.” (FSA)

Acrylamide can be, in large doses, a very nasty substance. It is used as an industrial sealant, and workers with very high exposures suffered serious neurotoxicity. Very high doses have been shown to increase the risk of mice getting cancer. ̽��ֱ��IARC (International Agency for Research on Cancer) considers it a ‘probable human carcinogen’, putting it in the same category as many chemicals, red meat, being a hairdresser and shift-work.

However, there is no good evidence of harm from humans consuming acrylamide in their diet: Cancer Research UK say that “At the moment, there is no strong evidence linking acrylamide and cancer.”

This is not for want of trying. A massive report from the European Food Standards Agency (EFSA) lists 16 studies and 36 publications, but concludes

In the epidemiological studies available to date, AA intake was not associated with an increased risk of most common cancers, including those of the GI or respiratory tract, breast, prostate and bladder. A few studies suggested an increased risk for renal cell, and endometrial (in particular in never-smokers) and ovarian cancer, but the evidence is limited and inconsistent. Moreover, one study suggested a lower survival in non-smoking women with breast cancer with a high pre-diagnostic exposure to AA but more studies are necessary to confirm this result. (p185)

Remember that each study is testing an association with a long list of cancers, so using the standard criteria for statistical significance, we would expect 1in 20 of these associations to be positive by chance alone.

A standard response might be the over-used cliché: ‘absence of evidence is not evidence of absence’. If there has been a huge effort to find an association, and none has been found, it’s true that this may not be direct evidence of the absence of an effect (though this can never be proved anyway). But it can be considered evidence of something that is not very important.

Given the numbers provided by EFSA and FSA, it is perhaps unsurprising that no association has been shown in large studies. EFSA calculated a BMDL10 of 170 µg/kg body weight/day — this means it is unlikely that exposures at this level would cause tumours in mice (technically it is the lower end of a confidence interval for the dose that would cause 10% increased tumours). They then compare this with human acrylamide exposure obtained from multiple detailed dietary surveys, which for adults has an average of 0.56 and a ‘high’ of 1.1 µg/kg/day, in the sense that 97.5% of people consume less than this. ̽��ֱ��BMDL10 is then divided by these exposures to give the ‘margin of exposure’, which rather confusingly end up being high for low risks and low for high risks.

So, for example, adults with the highest consumption of acrylamide could consume 160 times as much and still only be at a level that toxicologists think unlikely to cause increased tumours in mice (that's essentially what the ‘margin of exposure’ means).

This all seems rather reassuring, and may explain why it’s been so difficult to observe any effect of acrylamide in diet. But, for cancer, toxicology committees demand a rather arbitrary margin of exposure of 10,000 before considering the chemical essentially acceptable.

Reactions to the FSA’s Go for Gold campaign may range from the extremes of encouraging obsessive concern in the worried-well, to irate editorials on yet another intrusion from the ‘nanny state’. More worrying, people may just consider this yet another scare story from scientists, and lead them to dismiss truly important warnings about, say, the harms from obesity.

Cancer Research UK say that “researchers estimate that overweight and obesity are behind around 18,000 cases of cancer each year in the UK”. In stark contrast, the FSA provide no estimate of the current harm caused by acrylamide, nor the benefit from any reduction due to people following their advice. To be honest, I am not convinced it is appropriate to launch a public campaign on this basis.

̽��ֱ��Winton Centre for Risk and Evidence Communication is a new centre hosted within the Department of Pure Mathematics and Mathematical Statistics.

A new campaign is warning people that burning some food, such as toast, is a potential cancer risk. Here, the evidence for this claim is explored by David Spiegelhalter, Professor of the Public Understanding of Risk at the new Winton Centre for Risk and Evidence Communication.

People may just consider this yet another scare story from scientists, and lead them to dismiss truly important warnings about, say, the harms from obesity

David Spiegelhalter

Smallbrainfield

Toast

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Baboons watch neighbours for clues about food, but can end up in queues

fpjl2 — Wed, 20 Apr 2016 09:01:05 +0000

Latest research on social networks in wild baboon troops has revealed how the animals get information from each other on the whereabouts of food. However, once information reaches a high status baboon, subordinates often end up in a queue for scraps.

A new study, by researchers from the ̽��ֱ�� of Cambridge and the Zoological Society of London, shows how baboons monitor each other for changes in behaviour that indicate food has been found, such as hunching over to scoop it up.

This ‘socially learned’ information gets transmitted through proximity: those with more neighbours are more likely to spot when someone starts feeding. Once they do, baboons will head towards the food.

Information then starts to spread through the troop, as more baboons observe feeding behaviour or notice their neighbours moving in the direction of food. However, troop hierarchy ultimately kicks in – with the most dominant member in the vicinity, usually a male, wading in to claim the spoils.

At this point, surrounding baboons will often form what can appear to be a queue, to determine who gets to explore that patch of ground next.

These queues reflect the complex interactions within a baboon troop. ̽��ֱ��sequence of baboons in a queue depends on status – sometimes through birth-right – as well as social and familial relationships to the particular baboon occupying the food patch.

̽��ֱ��new research, published in the open access journal eLife, breaks down the transmission of social information through a baboon troop into three stages:

Acquiring information: observing behaviour that suggests food.
Applying information: exploring the food patch (even if no food is left).
Finally, exploiting information: actually getting to eat.

̽��ֱ��researchers used social networking models to show how being close enough to spot behaviour change is the only driver for acquiring knowledge.

When it comes to applying and exploiting social knowledge, however, the characteristics of individual baboons – whether its sex, status, boldness, or social ties in grooming networks – determine who gets to eat, or where they are in any queue that forms.

Baboon troops can be sizable, sometimes as many as 100 members, with the troops in the latest study numbering around 70. On average, less than 25% of a troop – around 10 individuals – acquired information of a food patch, with less than 5% of the troop actually exploiting it.

“Who actually gets to eat is only half the story,” says Dr Alecia Carter, from Cambridge’s Department of Zoology, who led the research.

“Just looking at the animals that capture the benefits of information, in this case food, doesn’t reflect the real pattern of how information transmits through groups. Many more animals acquire information, but are limited in their use of it for a variety of reasons.”

To conduct the study, researchers snuck handfuls of maize corn kernels, a high-energy baboon favourite (“like finding a stash of chocolate bars”) into the path of two foraging troops of wild chacma baboons in Tsaobis Nature Park, Namibia.

Once a troop member found the food, the researchers recorded the identities of baboons that spotted the animal eating, accessed the food patch, and got anything to eat.

Carter says that the best place for low-ranking baboons is often the peripheries, in the hopes of finding food and grabbing a few kernels before information spreads, and they are supplanted by the local dominant.

“ ̽��ֱ��more dominant a baboon is, the more spatially central in the troop they tend to be – as they can afford to be there. This provides more opportunities to gain information through the wider network,” says Carter.

Low-rankers that discover food will sometimes try to eat as stealthily or as quickly as they can, but, once a dominant has taken control of the food patch, a queue will often form. Grooming relationships to the feeding dominant can help a subordinate jump up a queue, although much of it is dictated by status.

For females, status is a birth-right that remains fixed throughout a baboon’s life. While human societies historically privilege the firstborn, in baboon troops maternal lineage is ranked by lastborn – with each new female baby replacing the last in terms of hierarchy.

Young males hold the same rank as their mother until they reach adolescence, usually around the age of six, and start asserting dominance through their bigger size, leading to shifts in status.

“It is relatively easy to collect dominance data, as baboons are constantly asserting dominance,” explains Carter. “Low-cost assertions of dominance, such as pushing an individual out of small patches of food, help to mitigate high-cost assertions, such as fights, and maintain the order.”

“However, baboons can mediate their status to a minor extent by having good grooming relationships, and low-ranking individuals have a slightly higher chance of applying and exploiting information if they are central in a grooming network. Over a lifetime of food opportunities, this may prove important for fitness.”

While baboons acquire information about food locations from watching others, they can also use social learning to see when that food is likely to be gone. Interestingly, the researchers found that males and females will often use this information in different ways.

“Baboons are highly vigilant, and constantly pay attention to what their neighbours are up to. When those in a food patch are sifting through dirt and clearly coming up empty-handed, most females will walk off, and won’t waste their time,” says Carter.

“Males on the other hand, particularly young males, are amazingly persistent, and will stay in a patch shifting sand around for a very long time in the hopes of finding a stray kernel.

“We hypothesise that, while males can afford to expend the energy, adult females are lactating or pregnant most of the time, so need to conserve their strength, and often end up using the information in a more practical way as a result.”

Baboons learn about food locations socially through monitoring the behaviour of those around them. While proximity to others is the key to acquiring information, research shows that accessing food depends on the complex hierarchies of a baboon troop, and those lower down the pecking order can end up queuing for leftovers.

̽��ֱ��more dominant a baboon is, the more spatially central in the troop they tend to be – as they can afford to be there

Alecia Carter

Baboon troop

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Laser technique promises super-fast and super-secure quantum cryptography

sc604 — Mon, 04 Apr 2016 15:06:38 +0000

Researchers have developed a new method to overcome one of the main issues in implementing a quantum cryptography system, raising the prospect of a useable ‘unbreakable’ method for sending sensitive information hidden inside particles of light.

By ‘seeding’ one laser beam inside another, the researchers, from the ̽��ֱ�� of Cambridge and Toshiba Research Europe, have demonstrated that it is possible to distribute encryption keys at rates between two and six orders of magnitude higher than earlier attempts at a real-world quantum cryptography system. ̽��ֱ��results are reported in the journal Nature Photonics.

Encryption is a vital part of modern life, enabling sensitive information to be shared securely. In conventional cryptography, the sender and receiver of a particular piece of information decide the encryption code, or key, up front, so that only those with the key can decrypt the information. But as computers get faster and more powerful, encryption codes get easier to break.

Quantum cryptography promises ‘unbreakable’ security by hiding information in particles of light, or photons, emitted from lasers. In this form of cryptography, quantum mechanics are used to randomly generate a key. ̽��ֱ��sender, who is normally designated as Alice, sends the key via polarised photons, which are sent in different directions. ̽��ֱ��receiver, normally designated as Bob, uses photon detectors to measure which direction the photons are polarised, and the detectors translate the photons into bits, which, assuming Bob has used the correct photon detectors in the correct order, will give him the key.

̽��ֱ��strength of quantum cryptography is that if an attacker tries to intercept Alice and Bob’s message, the key itself changes, due to the properties of quantum mechanics. Since it was first proposed in the 1980s, quantum cryptography has promised the possibility of unbreakable security. “In theory, the attacker could have all of the power possible under the laws of physics, but they still wouldn’t be able to crack the code,” said the paper’s first author Lucian Comandar, a PhD student at Cambridge’s Department of Engineering and Toshiba’s Cambridge Research Laboratory.

However, issues with quantum cryptography arise when trying to construct a useable system. In reality, it is a back and forth game: inventive attacks targeting different components of the system are constantly being developed, and countermeasures to foil attacks are constantly being developed in response.

̽��ֱ��components that are most frequently attacked by hackers are the photon detectors, due to their high sensitivity and complex design – it is usually the most complex components that are the most vulnerable. As a response to attacks on the detectors, researchers developed a new quantum cryptography protocol known as measurement-device-independent quantum key distribution (MDI-QKD).

In this method, instead of each having a detector, Alice and Bob send their photons to a central node, referred to as Charlie. Charlie lets the photons pass through a beam splitter and measures them. ̽��ֱ��results can disclose the correlation between the bits, but not disclose their values, which remain secret. In this set-up, even if Charlie tries to cheat, the information will remain secure.

MDI-QKD has been experimentally demonstrated, but the rates at which information can be sent are too slow for real-world application, mostly due to the difficulty in creating indistinguishable particles from different lasers. To make it work, the laser pulses sent through Charlie’s beam splitter need to be (relatively) long, restricting rates to a few hundred bits per second (bps) or less.

̽��ֱ��method developed by the Cambridge researchers overcomes the problem by using a technique known as pulsed laser seeding, in which one laser beam injects photons into another. This makes the laser pulses more visible to Charlie by reducing the amount of ‘time jitter’ in the pulses, so that much shorter pulses can be used. Pulsed laser seeding is also able to randomly change the phase of the laser beam at very high rates. ̽��ֱ��result of using this technique in a MDI-QKD setup would enable rates as high as 1 megabit per second, representing an improvement of two to six orders of magnitude over previous efforts.

“This protocol gives us the highest possible degree of security at very high clock rates,” said Comandar. “It could point the way to a practical implementation of quantum cryptography.”

Reference:
L.C. Comandar et al. ‘Quantum key distribution without detector vulnerabilities using optically seeded lasers.’ Nature Photonics (2016). DOI: 10.1038/nphoton.2016.50

A new method of implementing an ‘unbreakable’ quantum cryptographic system is able to transmit information at rates more than ten times faster than previous attempts.

This protocol gives us the highest possible degree of security at very high clock rates

Lucian Comandar

Depiction of indistinguishable photons leaving through the same output port of a beam splitter

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Intelligent airports and greener smart phones: award-winning Cambridge innovation

bjb42 — Wed, 13 Apr 2011 09:59:42 +0000

Airport queues. No one likes them, but in the modern world we’ve come to accept them as part of our travel routine. Equally, many people these days would struggle without their smart phones, but they take a toll on the environment and are expensive to produce.

Cambridge research that aims to tackle these issues has been celebrated at the UK ICT Pioneers Competition, an Engineering and Physical Sciences Research Council initiative which recognises the work of exceptional PhD students and researchers in the information and communications technologies.

̽��ֱ��intelligent airport

As demand for flights increases, airports are becoming increasingly congested, but environmental concerns make expansion a contentious issue. Sithamparanathan Sabesan, from the Department of Engineering, believes that tagging could provide an answer. ̽��ֱ��real-time, accurate identification of passengers and their luggage to within a metre of their locations would dramatically increase efficiency in security checks, lost luggage recovery, delayed passengers and the daily ebb and flow of air travel.

‘Passive’ tags have no batteries, making them viably cheap to produce; the key is devising a reliable method of detecting these tags with such accuracy, and over much greater distances than previously possible. Sabesan says he and his collaborators - Dr Michael Crisp, Prof. Richard Penty and Prof. Ian White - have cracked it using radio frequencies, and they’ve created a proof of principle demonstrator to show it works.

“Our demonstrator shows that this system could be 100 per cent accurate, as well as locating passive tags to within a metre, overtaking current conventional systems,” says Sabesan. “These breakthroughs are paving the way for a wide range of new applications. Key players in retail, airlines, manufacturers and document tracking have offered us trials, which we expect to carry out in 12-24 months.”

It is predicted that the Real Time Locations System (RTLS) could save airlines in excess of £400m, as well as significantly reducing the now traditional airport waiting times. Other industries have also shown interest in the project. Retail groups are looking at the technology with a view to shrinking checkout queues and reducing shoplifting. Sabesan, who came to Cambridge to work with ̽��ֱ�� spin-off company ARM Ltd before beginning his PhD in 2008, won the Connected World category at the ICT awards. He currently has two patents pending for his work and has just been elected to a junior research fellowship at Girton College.

Green touchscreens

̽��ֱ��Innovation for Sustainability category was won by Jens Christensen, also from the Department of Engineering, for his research into acoustic pulse recognition, and its application in the world of smart phones. Whilst the sight of people tapping and swiping at their mobile phone screen has become commonplace, it is the noises and vibrations resulting from these actions that Christensen is interested in.

By processing the various sounds into commands such select, scroll, zoom etc, the technology developed by Christensen and his colleagues at Input Dynamics converts every external edge of the phone into a touch-sensitive surface. ̽��ֱ��software uses existing microphones that most handsets carry, so it can be fitted with a few tweaks to enhance functionality and even add touch command capabilities to non-touch phones in a cost-effective way.

“Current touchscreen implementations rely on compounds that are in limited supply and consequently extremely expensive, which has an impact on both the environment and the consumer,” says Christensen. “Our technology TouchDevice™ dispenses with all of this by making better use of the hardware already present in the device.”

̽��ֱ��possible applications for the technology are vast as, in theory, walls and tables could be activated using microphones and the acoustic software. Could this potentially spell the end for such everyday staples as the light switch and the

TV remote?

“My research has applications far beyond what I have been able to imagine. This technology is highly customisable and any surface could potentially be made active, so that the technology can adapt to the user rather than the other way around.”

Christensen went on to take an additional prize at the ICT Pioneer awards, following a pitch to a ‘Dragons Den’ style panel of academics and industry experts. TouchDevice™ was voted by the panel to have the strongest commercial case, with Chief Executive of EPSRC Professor David Delpy describing the technology as “a win for both the customers and industry, fulfilling an unmet customer demand and satisfying the industry's need for newer and cheaper technologies”.

Two Cambridge researchers have received prizes at the ICT Pioneers awards for their groundbreaking approach to modern problems.

My research has applications far beyond what I have been able to imagine."

Jens Christensen

Ian Crowther from Flickr

Phone home

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