How Twitter could save your life

Inane chat about runny noses, or pandemic predictor?

Back in 2010 AMC set up co-ordinated “zombie attacks” in major cities around the world to promote its zombie thriller series The Walking Dead. Gaggles of blood-dripping “walkers” invaded trains and lurched around landmarks like Big Ben and The Prado Museum. Just one small scratch, or, worse, a desperate, flesh-eating bite, and you would become a zombie too – in the drama, of course.

AMC’s most popular programme now pulls in over 12 million viewers per episode and has nearly 1.5 million Twitter followers, each obsessed with the dramatic, but scarily plausible, scenario of a true life version of blockbuster films like Outbreak, Contagion or 28 Days later.

But as Twitter continually proves itself to be such an adept viral tool, the sheer number of users – which is 500 million and counting – flocking to its pages could make it a hefty ally in the fight to contain such an outbreak. Twitter, it seems, may not only be the best place to send a  meme like the walking dead  ‘viral’, but also the perfect platform for stopping a virus dead in its tracks.

Twitter users react to current events and tweets contain real-time information about their perspective and location. If Lori Grimes, for example, had been on Twitter, could word have spread faster than The Walking Dead’s zombie outbreak? And could Contagion’s MEV-1 virus have been prevented if Beth Emhoff had tweeted about her supposed cold symptoms?

These questions might read like science fiction, but Professor Simon Hay at the UK’s University of Oxford believes there is a “revolution occurring” in the amount of public health data that is available through social media, particularly from Twitter.

While scientists have traditionally used mapping techniques to track outbreaks, it is just 4 per cent of infectious diseases that have been effectively mapped. New technology is required to improve results and Twitter could provide the answer.

In fact, Twitter has already provided geo-positioned information to inform scientists about public health. A study from the University of Iowa proved that content embedded in Twitter feeds relating to the H1N1 flu outbreak in 2009 allowed the tracking of “rapidly-evolving public sentiment” and “actual disease activity”.

By using Twitter's streaming application programmer's interface (API), the study explored public sentiment from 29 April to 1 June 2009 by identifying 951,697 tweets out of 334,840,972 that matched specified search terms, such as flu, swine, influenza, H1N1 and illness.

The second phase selected 4,199,166 tweets – which conformed to certain guidelines, such as they had to be in English and originate from the US – from eight million influenza-related tweets that included relevant keywords sent between 1 October and 31 December 2009. The study found that these Twitter feeds actually predicted outbreaks one to two weeks in advance of traditional surveillance.

Scientists are currently struggling to map the current outbreak of the H7N9 avian influenza virus in China – which is considered by the World Health Organisation to be a “serious threat” (126 have been infected to date and 24 have died), despite it not spreading through people as yet – so why isn’t Twitter’s data stream being utilised?

Could it be due to the lack of Twitter users in China? According to a programmer (@ooof) on the South China Morning Post blog, the number of live active Twitter users could be as little as 18,000. If this number was more, would scientists have been better able to predict this very real threat to our society’s health?

As an online flu detector exists in the UK, which has been created by a team at the University of Bristol through identifying keywords from Twitter’s geo-located content, then couldn’t similar programs be used to identify and predict other, more serious, infections?

Twitter has come a long way since it launched, when it attracted intense criticism from naysayers questioning why they would want to tweet inane information about an erupting spot or runny nose. But, in the battle against pandemic outbreaks, it is ironically these kinds of observations that could empower Twitter to become a sophisticated tool and actually be more than just a social lifesaver in the future.

Frances Cook is a freelance energy, transport and lifestyle reporter. She has worked for NRI Digital.

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Inside Big Ben: why the world’s most famous clock will soon lose its bong

Every now and then, even the most famous of clocks need a bit of care.

London is soon going to lose one of its most familiar sounds when the world-famous Big Ben falls silent for repairs. The “bonging” chimes that have marked the passing of time for Londoners since 1859 will fall silent for months beginning in 2017 as part of a three-year £29m conservation project.

Of course, “Big Ben” is the nickname of the Great Bell and the bell itself is not in bad shape – even though it does have a huge crack in it.

The bell weighs nearly 14 tonnes and it cracked in 1859 when it was first bonged with a hammer that was way too heavy.

The crack was never repaired. Instead the bell was rotated one eighth of a turn and a lighter (200kg) hammer was installed. The cracked bell has a characteristic sound which we have all grown to love.

Big Ben strikes. UK Parliament.

Instead, it is the Elizabeth Tower (1859) and the clock mechanism (1854), designed by Denison and Airy, that need attention.

Any building or machine needs regular maintenance – we paint our doors and windows when they need it and we repair or replace our cars quite routinely. It is convenient to choose a day when we’re out of the house to paint the doors, or when we don’t need the car to repair the brakes. But a clock just doesn’t stop – especially not a clock as iconic as the Great Clock at the Palace of Westminster.

Repairs to the tower are long overdue. There is corrosion damage to the cast iron roof and to the belfry structure which keeps the bells in place. There is water damage to the masonry and condensation problems will be addressed, too. There are plumbing and electrical works to be done for a lift to be installed in one of the ventilation shafts, toilet facilities and the fitting of low-energy lighting.

Marvel of engineering

The clock mechanism itself is remarkable. In its 162-year history it has only had one major breakdown. In 1976 the speed regulator for the chimes broke and the mechanism sped up to destruction. The resulting damage took months to repair.

The weights that drive the clock are, like the bells and hammers, unimaginably huge. The “drive train” that keeps the pendulum swinging and that turns the hands is driven by a weight of about 100kg. Two other weights that ring the bells are each over a tonne. If any of these weights falls out of control (as in the 1976 incident), they could do a lot of damage.

The pendulum suspension spring is especially critical because it holds up the huge pendulum bob which weighs 321kg. The swinging pendulum releases the “escapement” every two seconds which then turns the hands on the clock’s four faces. If you look very closely, you will see that the minute hand doesn’t move smoothly but it sits still most of the time, only moving on each tick by 1.5cm.

The pendulum swings back and forth 21,600 times a day. That’s nearly 8m times a year, bending the pendulum spring. Like any metal, it has the potential to suffer from fatigue. The pendulum needs to be lifted out of the clock so that the spring can be closely inspected.

The clock derives its remarkable accuracy in part from the temperature compensation which is built into the construction of the pendulum. This was yet another of John Harrison’s genius ideas (you probably know him from longitude fame). He came up with the solution of using metals of differing temperature expansion coefficient so that the pendulum doesn’t change in length as the temperature changes with the seasons.

In the Westminster clock, the pendulum shaft is made of concentric tubes of steel and zinc. A similar construction is described for the clock in Trinity College Cambridge and near perfect temperature compensation can be achieved. But zinc is a ductile metal and the tube deforms with time under the heavy load of the 321kg pendulum bob. This “creeping” will cause the temperature compensation to jam up and become less effective.

So stopping the clock will also be a good opportunity to dismantle the pendulum completely and to check that the zinc tube is sliding freely. This in itself is a few days' work.

What makes it tick

But the truly clever bit of this clock is the escapement. All clocks have one - it’s what makes the clock tick, quite literally. Denison developed his new gravity escapement especially for the Westminster clock. It decouples the driving force of the falling weight from the periodic force that maintains the motion of the pendulum. To this day, the best tower clocks in England use the gravity escapement leading to remarkable accuracy – better even than that of your quartz crystal wrist watch.

In Denison’s gravity escapement, the “tick” is the impact of the “legs” of the escapement colliding with hardened steel seats. Each collision causes microscopic damage which, accumulated over millions of collisions per year, causes wear and tear affecting the accuracy of the clock. It is impossible to inspect the escapement without stopping the clock. Part of the maintenance proposed during this stoppage is a thorough overhaul of the escapement and the other workings of the clock.

The Westminster clock is a remarkable icon for London and for England. For more than 150 years it has reminded us of each hour, tirelessly. That’s what I love about clocks – they seem to carry on without a fuss. But every now and then even the most famous of clocks need a bit of care. After this period of pampering, “Big Ben” ought to be set for another 100 or so years of trouble-free running.

The Conversation

Hugh Hunt is a Reader in Engineering Dynamics and Vibration at the University of Cambridge.

This article was originally published on The Conversation. Read the original article.