Saturday 29 November 2008

Climate Change News and closing in on 100 episodes

This week on the podcast, we take a look at the latest climate change news, and start reflecting on the science year that was, as we close in on 100 podcast episodes (this is episode 92).

The news items we discuss this week are:
  1. CO2 build-up in the atmosphere may prevent a coming ice-age. Ice-ages occur roughly every 100,000 years and are possibly due to small shifts in Earth's orbit which change the amount of solar energy hitting the surface. A build-up of CO2 and its associated heating may warm the Earth so much that the next ice-age is skipped. Humanity has burnt about 300 gigatonnes of carbon from fossil fuels during its existence, and even if only 1000 gigatonnes are eventually burnt (from total reserves of about 4000) then it is likely that the next ice age will be skipped, whilst the next five could be skipped if all recoverable fossil fuels were burnt. For more information, see the story at ABC Science;
  2. The bouquet of wine reflects the amount of fossil-fuel derived CO2 in the air at the time and place of the growing of the grapes. Carbon-14, an isotope of carbon, is made when Nitrogen atoms high in the atmosphere absorb neutrons from space (cosmic rays) . Over time, Carbon-14 decays to Nitrogen-14 , and so fossil fuels, made millions of years ago from decaying organic matter, contain almost no Carbon-14. Therefore, when fossil fuels are burned, the resultant CO2 is almost Carbon-14 free. As CO2 is used by plants to grow, the amount of Carbon-14 in the atmosphere at the time of growing is reflected, in this case, in the wine's bouquet. A low level of Carbon-14 means there was a lot of fossil fuel generated CO2 in the atmosphere at the time of growing. More information on Discovery Science;
  3. Wind farms could steer storms. Future mega-wind farms for renewable energy generation could have a massive effect on the weather because the large wind speeds they generate could cause disrupted air-ripples that spread out like waves over massive areas. The waves could even steer storms on the other side of the globe. More information on Discovery Science;
  4. Tibetan glaciers are melting faster than ever seen before. The Himalayan glaciers are melting so fast that the usual techniques for dating glaciers can't be used. Glaciers can be dated by looking for traces of leftover radioactivity from US and Soviet atomic bomb tests in the 1950s and 1960s. In the Tibetan samples, there are no signs at all of these tests, and the exposed surface of the glacier dates to 1944. More information at ABC Science;
If you are gazing at the sky this weekend (Thanksgiving to our American friends), then look to the sky to see Jupiter, Mars and the moon all gathered together.

We also start reflecting on the year that was with my much better-half Eugenia, who had to put up with me recording this here little podcast, and then having to listen to the episodes and smile! Her highlights from the year?
Listen to his podcast here:

Wednesday 26 November 2008

That time again - Movember

This year, the Mr Science Show has again entered the charity moustache growing contest, Movember. Movember supports men's-health charities, and this year in Australia, all money raised is going towards the Prostate Cancer Foundation of Australia and beyondblue - the national depression initiative. These issues are close to my heart as people close to me have suffered, and even died, because of prostate cancer and depression. Read more about the Fundraising Outcomes.

Did you know:
  • Depression affects 1 in 6 men....most don't seek help. Untreated depression is a leading risk factor for suicide.
  • Last year in Australia 18,700 men were diagnosed with prostate cancer and more than 2,900 died of prostate cancer - equivalent to the number of women who will die from breast cancer annually.
For more sciencey stuff on moustaches and Movember, here is everything you need:
To sponsor us, check out our Mo-space or donate directly from this link

Thanks y'all!

Wednesday 19 November 2008

Science on Stage

Dr Christopher Pettigrew, a post-doctoral researcher at the Department of Biochemistry in University College Cork, is no stranger to putting science on stage.

With the 2009 AAAS Dance your PhD competition up-and-running, we decided for this week's episode of the podcast to chat to Chris about his experiences in the public performance of science.

Chris has been involved in the communication of many difficult subjects through artistic means, such using interpretive dance to explain the Australian Goods and Services Tax (GST) and DNA . Chris plans on building upon his experiences in Australian theatre whilst in Cork, Ireland. As Dr Pettigrew says:

"Nothing says Double Helix like a rapid twirl."

Listen to his podcast here:

The 2009 AAAS Dance your PhD final contestants have been selected. To read more about them and watch their videos, visit The 2009 AAAS Science Dance Contest homepage.

Do you have any scientific ideas that you would like to see put on stage? Please let us know by leaving a comment here, or by emailing us.

Thursday 13 November 2008

Football Manager Lifetimes

I put this story together for Plus - I'll be writing their new regular Sports Column, which will focus on maths and sport. For more maths stories on sport, see previous Plus stories tagged with sport. And for more on this particular story, see it as published in The Plus Sports Page: Power Trip

Being the manager of a Premier League football club may seem like one of the most glamorous jobs in the world — with the fame comes fortune and the opportunity to travel (well, to Hull, Wigan and Portsmouth anyway). However, as far as job security goes, football managers live on the edge. Their terms can be terminated almost on a whim by their club's owner, and they live and die by their team's results.

It would seem that there is no way to predict how long their tenures will be. However, a collection of researchers from the UK, Singapore and the US have found that there may be a strong mathematical trend underlying how long football managers stay in their jobs.

Toke S. Aidt, Bernard Leong, William C. Saslaw and Daniel Sgroi found that the distribution of tenure lengths for managers of sporting teams in many countries obey power laws. Power laws are fascinating because they arise in a surprisingly large number of naturally occurring phenomena, such as the size of cities, stock market returns, cook book ingredients and even how many times certain words are used in long books.

A power law has the form

\[ y = ax^ b, \]

where x and y are variables and a and b are constants. The exponent b is usually negative, so y decreases as x increases. In the case of football managers, the researchers found that

\[ n=a(t+1)^ b, \]

where t is the length of a football manager's career and n is the number of managers dismissed at that time of their career. The actual values of the constants a and b vary from country to country and league to league, with the exponent b lying somewhere between -2 and -3 in all cases.

To derive this formula, the authors plotted tenure lengths of real managers against their time of dismissal and then set out to find the curve that best describes the data. In fact, to make things easier, they looked at logarithms, which turn a curve of this form into the straight line

\[ ln(n) = ln(a) + bln (t+1). \]

For tenures greater than one year, they found that in the English Premier League, football leagues across Europe, and American football and baseball competitions, there is a straight line of this form that fits the data. Moreover, the fit is statistically significant, that is, it’s not just due to chance.

The following graph is for English Premier League managers between 1874 and 2005.

A plot of the logarithm of managers' careers against number of managers dismissed

The logarithm of the length of managers' career plotted against the logarithm of the number of managers dismissed at that time of their career. The data can be approximated by a straight line and the fit is statistically significant. The data come from the English Premier League between 1874 and 2005.

But what does all this mean?

As we mentioned earlier, power laws are compelling as they can emerge from simple mathematical rules — the power law is often a macroscopic outcome of microscopic interactions between the players in the system (in this case football managers, the team, club owners and fans, etc). In fact, power laws are often seen as the signature of complexity. In the 1980s scientists found that there are dynamical systems based on simple rules which, through self-organisation, bring themselves into extremely sensitive states, where even the smallest change can cause wide-ranging and unpredictable chain reactions.

An often quoted example of this phenomenon involves a pile of sand. When you sprinkle sand on a table, a pile will build up and after a while reach a maximal slope: any additional grain of sand will cause avalanches whose number and size are impossible to predict. Such a sensitive state is called a critical state and this behaviour is called self-organised criticality. It is an interesting phenomenon, because it may explain "spontaneous" emergence of complexity in nature, which is not a result of someone forcing the system.

When a system has reached a critical state through self-organisation, it can often be described by power laws. In our sand example, the size distribution of the avalanches follows a power law. Power laws reflect complexity because they are similar on all scales. Suppose that the number n of avalanches of size s is described by the power law

\[ n=as^ b, \]

for some constants a and b. Now multiply s by a large number c, so you're now looking at large avalanches. These then follow the power law

\[ n=ac^ bs^ b, \]

which, apart from the constants involved, is essentially the same as that for smaller avalanches - the same type of behaviour occurs on all scales.

Given that the power law highlights the fact that there is something interesting going on, the researchers set out to find out what it was. What are the simple rules of football management that govern this system, and is there self-organised criticality?

The model

The authors constructed a model which includes a manager's reputation — this is either enhanced or diminished, depending on the result of each match. The core of the model is a round-robin tournament with 20 teams playing each other once at home and once away — just like in the Premier League. The probabilities of win, lose and draw were modelled as 37%, 26%, 37%, respectively — these probabilities are those observed in the English football league between the years 1881 and 1991 and are assumed to be independent of the managers involved.

The model starts with 20 randomly selected managers, each with a given reputation and tenure. (With a nod to realism, we will henceforth assume that all managers are male.) The initial reputation of each manager is described by a positive whole number, which is chosen at random from the numbers between the firing threshold and the poaching threshold (more on these in a moment). Each manager also starts with a random tenure length between 1 and 40 years. The managers gain reputation (+ 2 points in the model) every time their teams win, and lose reputation (-2 points) when their teams lose. There are no points for draws. Each game has equal importance and so each result is equally important for a manager's reputation.

The length of a manager's tenure depends on how his reputation evolves. Termination of tenure can occur for four reasons:

  • The manager loses his job when his reputation falls below the firing threshold — that is, he is sacked;
  • The manager is poached by another club when his reputation reaches the poaching threshold — that is, he gets a better deal;
  • The manager retires if he gets too old (another parameter that can be varied);
  • The manager's team is relegated to a lower league because it has the lowest reputation at the end of the season — the team is demoted out of the league.

When a manager leaves the system — that is, he is either fired or poached, relegated or retired — his place in the league is taken by another manager with tenure length of zero and a random starting reputation.

With these rules in place, the researchers ran many simulations, varying the random parameters in each run. Such a process is known as a Monte-Carlo simulation. They recorded the distribution of tenure lengths corresponding to one hundred years of competition. They found that for a very broad range of starting parameters, the model produced a tenure length distribution statistically indistinguishable from a power-law distribution. Similar results were obtained for different probability distributions of win, loss or draw. However, the researchers also found that power laws only emerge when a win enhances reputation by the same amount as it is decreased by a loss, and when each match has equal importance. The latter makes sense if you think that the aim of a Premier League team is to maximise its profit: you need to fill the stadiums and make as much advertising revenue as you can at each game. And as the Premier League is a first-past-the-post competition, each win has equal worth on the league table, with position on the table more than anything guaranteeing further advertising and merchandising returns.

Coming back to self-organised criticality, the researchers admit that their model does not prove the existence of this phenomenon in the world of sport. In fact, the model is not quite as self-organising as it could be, since certain parameters need to be artificially fixed at the outset. They do believe, however, that certain other factors point in the direction of self-organised criticality. The Premier League, they postulate, follows the Red Queen principle: it is an arms race where constant development is needed simply to compete. This explains why once a league has reached a self-organised critical state, it might stay there for a prolonged period of time. It is simply too difficult for a team to shake up the system, given that they are already in a process of continual change in order to stay with the pack. The term Red Queen comes from Lewis Carroll's Through the Looking-Glass in which the Red Queen says: "It takes all the running you can do, to keep in the same place".

What the results surprisingly show is that ability and talent, although obviously playing some role, do not play a major role in a manager's success. His survival is far more determined by the sacking and poaching thresholds and simple randomness in his team's results. 2007 Chelsea manager Avram Grant is a good example of this: as he started his tenure with a low reputation, despite his team's good results, probabilities took their toll and he was sacked at the end of the season.

In any case, it's hard to feel sorry for prematurely sacked Premier League managers when their average salaries are over £2 million.

For more info, see the following:

Thursday 6 November 2008

Here's why we need science communicators

From the Border Mail, Letters 01/10/2008

When I was a kid, we never had drought after drought.

Then we started with daylight saving. We started with a little bit, but now we have six months of the year daylight saving. It has just become too much for the environment to cope with.

It is so logical, for six months of the year we have an extra hour each day of that hot afternoon sun.

I read somewhere that scientific studies had shown there is a lot less moisture in the atmosphere which means we get less rain.

I believe this one hour extra sun is slowly evaporating all the moisture out of everything. Why can't the government get the CSIRO to do studies on this, of better still, get rid of daylight savings.

They have to do something before it is too late.


... And that's why we need science communicators!
This has also been reported in Failblog and somewhere in the smh.

Sunday 2 November 2008

Halloween Science Special

As it's Halloween, here is the Halloween news that I presented on Diffusion Science Radio this week. Diffusion can be heard on Monday nights at 6.30pm on 2SER 107.3 in Sydney, at various times across Australia on stations affiliated with the Community Radio Network, and on the Diffusion podcast.

1) Halloween, Candy and Science

What's worse: eating all the lollies collected on Halloween night at once, or spreading this out over the coming days and months?

When it comes to your teeth at least, it is far worse to ration your lollies all through the day, day after day than it is to gorge it all at once. Mark Helpin, a pediatric dentist at Temple University, says that snacking on candy keeps your teeth bathed in enamel-corroding acid, which is produced by bacteria feeding on the sugar in your mouth.

When you cover your teeth with sugar, oral bacteria cause a rise in acidity levels. This is neutralised when you brush your teeth. Even if you don't brush, saliva will eventually wash away the sugar and starve the bacteria. If you continually snake on chocolate and other lollies, the level of acidity stays constantly high, and this can lead to tooth decay.

Helpin also thinks that potato chips are just as bad, or worse, than lollies. Acid-producing bacteria feed on carbohydrates in potatoes, which are far more sticky than lollies and so hang around longer on your teeth. This poses an even greater risk for tooth-decay.

More information on ABC

2) Bigfoot revealed to be Halloween Costume

There's been a recent downturn in the fortunes of those hunting for Bigfoot, which a supposed frozen corpse of the animal turning out to be a Halloween costume. owner Tom Biscardi had paid an estimate $50,000 to Matthew Whitton and Rick Dyer for their frozen Bigfoot "corpse". Biscardi also hired Sasquatch detective Steve Kulls to check out the specimen.

Kulls was not a happy man, and neither, it turns out was Biscardi, especially after Whitton and Dyer ran off with his money.

"I extracted some [hair] from the alleged corpse and examined it and had some concerns," Kulls writes. "We burned said sample and said hair sample melted into a ball uncharacteristic of hair. Within one hour we were able to see the partially exposed head. I was able to feel that it seemed mostly firm, but unusually hollow in one small section. This was yet another ominous sign."

"Within the next hour of thaw, a break appeared up near the feet area. ... I observed the foot which looked unnatural, reached in and confirmed it was a rubber foot."

When Biscardi found out, he called Whitton and Dyer at their California hotel, who confirmed the hoax. However, when Biscardi went to look for them, they had disappeared with his money, and plenty of his dignity.

More information on

3) Vampire Moth

A population of vampire moths has been found in Siberia that entomologists suggest may have evolved from a purely fruit-eating species as there are only slight differences in their wing patterns from the herbivorous cousins, Calyptra thalictri.

When the Russian moths were experimentally offered human hands , the insects drilled their hook-and-barb-lined tongues under the skin and sucked blood.

Entomologist Jennifer Zaspel from the University of Florida said the discovery could shed light on how indeed caught a fruit-eating moth evolving blood-feeding behavior, it could provide clues as to how some moths develop a taste for blood.

It may be that blood-feeding in insects evolved from feeding on tears, dung, and pus-filled wounds.

"We see a progression from nectar feeding and licking or lapping at fruit juices to different kinds of piercing behaviours of fruits and then finally culminating in this skin piercing and blood-feeding," she said.

In addition, only male moths exhibit blood-feeding, which means that maybe its so the males can pass on salt to females during sex. This could provide a nutritional boost to young larvae that have sodium-poor diets.

More information on National Geographic

4) Trick-or-treat safety tips

Children are twice as likely to be hit by a car and killed on Halloween than on any other day of the year - so take care! More information at AJC

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