The Sasol Solar Challenge

This year’s Sasol Solar Challenge in South Africa is calling on solar car teams to sign up before May 1. The event will take place from September 24 to October 1 this year. Unlike the World Solar Challenge in Australia, it is a distance-based race, with a main course of about 2,000 km from Pretoria to Cape Town, and the possibility of driving additional loops up to 4,000 km or more. All the World Solar Challenge classes are permitted, plus the FIA Olympia class. Confirmed teams so far include:

Nuon Solar Team (Netherlands)

Nuon won the 2014 Sasol Solar Challenge and the 2015 World Solar Challenge. They are the clear favourites for this year’s event.

Nuon’s Nuna7S in South Africa in 2014 (photo: Nuon Solar Team)

North-West University (South Africa)

NWU came 11th in the the 2015 World Solar Challenge, ahead of South African rivals UKZN. They should do well on home turf this year.

NWU’s Sirius X25 in Australia in 2015 (my photo)

A number of other local and international teams have also expressed interest.

Update 1: Apparently Sheffield Hallam University will be there too ( ). They seem to be a new team, who are building an old-school symmetrical 4-wheel car.

Update 2: And it seems Tokai will be back in South Africa, duking it out with Nuon ( ).

Further updates here.

Praising Cambridge

Clare College, Cambridge (my photo)

The University of Cambridge has been mentioned repeatedly on this blog. It is one of the oldest universities in the world – so old, in fact, that nobody is quite certain when it began (it seems to have been up and running by 1226, however). Cambridge is home to the Cavendish Laboratory, where many of the greatest scientific discoveries were made (the electron, the neutron, the structure of DNA, and more). Cambridge is ranked 4th in the world on the Times Higher Education list of engineering institutions. In the humanities, C. S. Lewis moved there from Oxford in 1954.

The university buildings are scattered across the city, which tends to confuse people. I can recall a tourist asking me, on a visit I once made to Cambridge, “Where on earth is the university?”

The Cavendish Laboratory, Cambridge (photo: “RichTea”)

The university is also home to the Cambridge University Eco Racing team, which competes in the World Solar Challenge, and which fielded a rather unusual-looking design in 2013 and 2015:

Cambridge University Eco Racing team’s 2015 WSC entry (photo: CUER)

Praising Michigan

Angell Hall, University of Michigan

The University of Michigan is ranked 17th in the world on the Times Higher Education list of engineering institutions. It is located in the small city of Ann Arbor, and has over 40,000 students, who are required to take race and ethnicity courses as part of their degrees.

Since its founding in 1817, university staff and alumni have collected several Nobel prizes. The university is also proud to have America’s number one solar car team:

Michigan’s solar car Aurum comes 4th in the 2015 World Solar Challenge (my photo)

Beautiful sea sparkles

Noctiluca scintillans (photo: Maria Antónia Sampayo)

Noctiluca scintillans (above) is a bioluminescent marine dinoflagellate.

Noctiluca scintillans bioluminescence (photo: Sander van der Wel)

Noctiluca scintillans produces beautiful displays of bioluminescence round the world. Above and below, two examples of these “sea sparkles”. Lovely!

Noctiluca scintillans again (photo: Adrian Kingsley-Hughes)

Praising Delft

Library at TU Delft (photo: Nol Aders)

The Delft University of Technology (TU Delft) has been mentioned a few times on this blog. It is ranked 19th in the world on the Times Higher Education list of engineering institutions.

Its history goes back to 1842, when King Willem II founded a “Royal Academy for the education of civilian engineers, for serving both nation and industry, and of apprentices for trade.” It later became a Polytechnic. Following a period of competition with (and hostility from) traditional universities, it was given university status in 1905, thanks to theologian-politician Abraham Kuyper (who was thanked with an honorary doctorate in 1907).

Highlights of TU Delft’s research include the discovery (and naming) of viruses in 1898 (by Martinus Beijerinck), and the continued domination of the World Solar Challenge (TU Delft’s team won in 2001, 2003, 2005, 2007, 2013, and 2015, and came second in 2009 and 2011). One of the world’s great technical institutions!

TU Delft’s solar car Nuna8 wins the 2015 World Solar Challenge (my photo)

The US Primaries

Above are progressive delegate counts in the US Primary elections (data from, not yet including the results of two very close contests in Missouri). Below are the ratios between counts for the top contenders. Clinton is consistently getting three delegates for each of Sanders’ two and has, with “superdelegates,” pretty much got the Democrat nomination sewn up, it seems to me.

Cruz has been consistently getting more than double Rubio’s count, so it’s not surprising that Rubio has pulled out. Cruz was briefly eating into Trump’s lead, but has fallen back again – so Trump now seems likely, though not certain, to get the Republican nomination.

BMI revisited

One of the more infamous datasets floating around the Internet is the set of body measurements of Playboy centrefolds. Wired magazine reported on this dataset in 2009 and again last year, although I found their analysis a little disappointing.

Playboy has been around since 1953, and has influenced attitudes to women in a number of (largely negative) ways in that time. However, the numeric data has a life of its own, as Wired points out (and, in a complex system, tracking one component over time sheds light on the system as a whole). Of particular interest, in the light of my previous post about BMI, is the way Playboy sells a certain “ideal” female body shape. Playboy influences and is influenced by the general Zeitgeist in this regard (e.g. the fashion industry), but is also presumably influenced by inherently biological male preferences.

I’ve taken the 2009 dataset used by Wired, added more recent data screen-scraped from Wikipedia, and done my own analysis (all in R, of course). The chart below shows the results. These numbers may, as Wired points out, not be entirely accurate – but even if they are not, Playboy is still selling the body shape which those numbers describe.

The first thing to note is that 52% of Playboy centrefolds had a BMI (body mass index) below the healthy green zone on the chart. Like the fashion industry, Playboy is selling an unhealthily underweight female body shape. However, the average fashion model has a BMI of 17.6 (blue line on the chart), and the mean BMI of Playboy centrefolds has always been higher than that. This may be a case of inherently biological male preferences moderating the Zeitgeist’s drive towards ever thinner models.

The black line on the chart shows the smoothed mean BMI values (using 1st degree loess smoothing). There are some interesting temporal variations here. The mean BMI of Playboy centrefolds was stable at a healthy 19.4 up to early 1965, but then dropped steadily to an unhealthy 17.9 in early 1986. The mean BMI then increased again to 18.5 in early 2009, and then dropped sharply again to 18 in early 2016 (the last three trends are statistically significant at p = 0.00000000003%, 0.12%, and 0.53% respectively). The two minima show up again if we look at the lowest BMI values – those 16 or less. The table below shows that there were two of these around 1980, and four others after 2009. These changes may reflect a movement from the Twiggy generation to the Cindy Crawford generation to the Kate Moss generation. Whatever lies behind the numbers, however, it is disturbing to think that the 1970’s pressures on women to become unhealthily underweight may have returned stronger than ever.

Month Height Weight BMI
July, 1978 168 cm 43 kg 15.3
October, 1982 173 cm 48 kg 16.0
February, 2010 170 cm 46 kg 16.0
September, 2013 160 cm 39 kg 15.1
July, 2014 173 cm 48 kg 16.0
August, 2015 173 cm 45 kg 15.2

For comparison, the chart below shows the estimated BMI for some winners of the Miss World and Miss Universe beauty pageants (in the absence of weight data, BMI is estimated from body measurements, where these are available, using a regression equation derived from a standard anthropometric database). Here 57% of the women are underweight. The mean estimated BMI is roughly steady at 18.7 (just inside the healthy range) up until the year 2000, but from 2000 onwards there is a significant decline (p = 4%). More data would be useful here, but it does seem that (in spite of bans on underweight fashion models in some countries) there are indeed renewed pressures on women to become unhealthily underweight. Furthermore, the post-2009 downturn in the mean BMI of Playboy centrefolds seems to have been in reaction to a more global trend that had already begun a decade earlier.

The words of the fictional demon in C. S. Lewis’s 1942 book The Screwtape Letters still seem relevant today (although Lewis clearly did not foresee the current industry in silicone breast implants, which Wired also comments on):

It is the business of these great masters [of the Lowerarchy] to produce in every age a general misdirection of what may be called sexual ‘taste.’ This they do by working through the small circle of popular artists, dressmakers, actresses, and advertisers who determine the fashionable type. … The age of jazz has succeeded the age of the waltz, and we now teach men to like women whose bodies are scarcely distinguishable from those of boys. Since this is a kind of beauty even more transitory than most, we thus aggravate the female’s chronic horror of growing old … We have engineered a great increase in the licence which society allows to the representation of the apparent nude (not the real nude) in art, and its exhibition on the stage or the bathing beach. It is all a fake, of course; the figures in the popular art are falsely drawn … As a result we are more and more directing the desires of men to something which does not exist – making the rôle of the eye in sexuality more and more important and at the same time making its demands more and more impossible.

Fifty years of tribology

Severe wear in a bearing (photo: Jean-Jacques Milan)

Cambridge University is celebrating 50 years of tribology, the study of friction, wear, and lubrication.

Actually, this is a field that goes back to Leonardo da Vinci, but the name was only coined 50 years ago, when Peter Jost wrote an influential report on the costs associated with friction and wear. That report, published on 9 March 9 1966, estimated that that improvements in lubrication and maintenance in industry could save the British economy £500 million per year.

Today, tribology is recognised as an important part of mechanical engineering as well as of medical engineering. Thanks, Peter!

X-ray of an artificial hip joint

Donald Trump and Demographics

It has been pointed out in recent times that the death rate for Non-Hispanic White males and females in the USA is now higher than for the general US population (data above from the recent US National Vital Statistics Report). In fact, in 2013, age-adjusted death rates for Non-Hispanic Whites actually rose (by 0.6, from 876.2 to 876.8 per 100,000 for males, and by 0.8, from 637.6 to 638.4 per 100,000 for females).

A recent article in PNAS shows that this apparently small increase results from a substantial increase in death rates among middle-aged Non-Hispanic White men and women (ages 45-54), and blames an increase in drug and alcohol poisonings and in suicide. The increases in death rate and in poisonings and suicide are particularly pronounced among Non-Hispanic White men and women without a college education. The chart below shows the crude death rates over time for Non-Hispanic White men and women in this age group, but does not reflect the impact of level of education (data from CDC WONDER Online Database):

The NY Times is among those that has run the story, and it has also been pointed out that the increases appear to be greater among women than men, greater in Southern states, and partly due to a reversal of progress against diabetes and other diseases.

This tragic phenomenon seems to be linked to a loss of blue-collar jobs in the USA, and a lack of access to affordable healthcare (which, in the USA, is often linked to employment). The map below shows the overall death rates for Non-Hispanic Whites in this age group by state (data from CDC WONDER Online Database, averaged over 2010–2014):

Jeff Guo at the Washington Post demonstrates that it is this group of people who are voting for Donald Trump. This group seems to feel that both major US political parties have ignored their very real problems. The Guardian describes what some of those problems are. The support for Trump appears to be a case of desperately clutching at straws, but will presumably continue until the major parties (1) acknowledge that these people matter and (2) come up with a plan for addressing their problems.

US counties by poverty rate (image by “TastyCakes”)