allotrope – Page 40 – Akshat Rathi

Squirrels and climate change

August 8, 2012January 25, 2014 Akshat RathiLeave a comment

Winter is a pain in the animal kingdom. Birds can flee it by migrating to warmer climes but grounded beasts, including mammals, have no choice but to stick around. To cope, many species have learned to hibernate. Some, like the Columbian ground squirrel, spend up to nine months of each year in their alcoves. This conserves energy but leaves them with only three months to plump up for the next winter and, crucially, to procreate.

To make matters worse, climate change is leading them to emerge from hibernation later than usual. On the face of it, global warming should mean that the critters have longer ice-free periods in which to go about their evolutionary tasks. But it can also disturb weather patterns, which may have the opposite effect. Jeffrey Lane, an evolutionary biologist at the University of Edinburgh, in Britain, points out that in the squirrels’ natural habitat of the Canadian Rockies, climate change manifests itself in late-spring snow storms.

Because female Columbian ground squirrels remain in their place of birth, the researchers were able to tag and observe them and their offspring each year for the past two decades. A typical female would bear three kittens. On average, only 30% of them survive the first winter, enough to sustain population numbers since female squirrels can expect three or four litters in their lifetime. If the proportion falls, however, the population dwindles.

As Dr Lane and his colleagues report in Nature, in the first decade of the study the number of squirrels dropped just once. But it fell in four of the past ten years. Dr Lane speculates that this might be explained by the fact that over the past 20 years the late snow has delayed the melting of ice by half a day each year, on average, shortening the squirrels’ breeding and feeding season by several days and disrupting their life cycles. Since mothers have less time to squirrel away (if you will) nutrients in their bodies before it is time to hibernate, the suckling kittens are left more vulnerable.

Correlation is not causation, of course, and other factors might be behind the decline in the number of squirrels. But longer winters are unlikely to help.

Also published on economist.com.

References:

Lane et al., Nature, 2012.
Lane et al., J. Evol. Biol., 2011, 1949.

Image credit: Jeffrey Lane.

The physics of sand castles: Just add water

August 2, 2012January 25, 2014 Akshat RathiLeave a comment

A day out on the beach would be incomplete without a sand castle. The mightier the castle, the better. But sand is next to useless as a building material. Without water it simply spreads out as wide as possible. So in search of a good recipe Daniel Bonn, a physicist at the University of Amsterdam, and colleagues have stumbled upon a formula for making the perfect sandy redoubt.

As they reveal in a paper published this week in Scientific Reports the key is to use sand with only 1% water by volume. Wet sand has grains coated with a thin layer of water. Owing to water’s surface tension this thin coat acts like skin stretched over many grains, holding them together by creating bridges between the grains. The strength of these bridges is enough to fight Earth’s gravity and prevent the structures from buckling under their own weight.

An easy way to achieve the right amount of water, Dr Bonn suggests, is to tamp wet sand in a mould (open at the top and the bottom) with a thumper at least 70 times, as he did in his experiments.

As for the design itself, unsurprisingly, the wider the base the taller the castle. According to calculations, using ideally moist sand, a column with a three inch diameter could rise as high as two metres. At 12 metres, the current world record for the tallest sandcastle, set by Ed Jarrett in 2011, used a base of roughly 11 metres. If Dr Bonn is right, sand engineers could in principle beat that with a castle thrice the height upon the same foundation.

First published in The Economist.

Image from here.

Online software piracy: Head in the clouds

July 25, 2012January 25, 2014 Akshat Rathi1 Comment

As more people use “cloud computing” services like webmail and do word-processing via a browser, software makers fret that today’s software piracy will migrate to the cloud too. The Business Software Alliance (BSA), a trade group, this month released a survey that emphasises that 30% of users in rich countries and 45% in poor ones have a “likelihood of sharing log-in credentials for paid services.” It is “a worrisome new avenue for software licence abuse,” says the BSA’s boss, Robert Holleyman.

Yet the closer one looks at the BSA’s study, the murkier such conclusions become.

Take the dramatic figures above. It is not quite so bad. The percentages come from a question in which people were asked if they had ever shared their log-in details for paid services. Some 15% of people in rich countries and 34% in poor countries said they had for personal use. For business use, it was 30% and 45% respectively. The larger figures amplify the BSA’s point, but they are not necessarily the most accurate.

Moreover the respondents were only those who had paid for cloud services, which was a fraction of users. Cloud services are generally based on a “freemium” model, whereby basic use costs nothing and a premium version is paid for. According to the BSA’s own data, only half of computer users tap cloud services, of which only one-third use it for business, of which two-thirds pay. Of the small subset that remain, the minority share log-ins.

This changes things considerably. If the BSA figures were adjusted for all this, the potential piracy figures could be as low as between 2% and 6% of users—as much as 20 times less than the group claims. (The BSA’s data is online here.)

Worse, the BSA and Ipsos Public Affairs, who conducted the survey, didn’t think to ask or examine whether sharing log-in details violated the terms of service. It may very well be the contrary: that the service had communal uses as a feature. Mr Holleyman bends over backwards to acknowledge as much on a blog post. Yet the overall impression that the BSA gives is that cloud users are poised to rob firms of their rightful revenue.

There are other anomalies. The BSA only considered PC use, when many people use cloud services over tablets and mobile phones, especially in poor places. And the survey, of 14,702 people in 33 countries, presumes to speak with confidence about the “developing” world but not a single African country is represented—an odd omission, since it is a fast growing market.

The annual BSA piracy study released this year in May estimated losses to the PC software industry in 2011 of $63 billion. That princely sum would make software piracy the 66th largest economy in the world, worth more than Syria and Croatia. The BSA reaches that amount by multiplying the estimated number of computers containing pirated software with the retail price of the software.

It is a specious way of calculating piracy (as we explored in an article in 2005 entitled “BSA or just BS?”). Many people would not buy the product at the expensive retail price. That’s why they steal it, after all. Still, the BSA’s dubious figures influence public policy. Mr Holleyman was invited to testify at a congressional hearing on July 25th on cloud computing, where his prepared remarks specifically cited “credential sharing” as a piracy challenge.

Be it in the cloud or back down on Earth, software piracy is theft and is wrong. The crime should be prosecuted and technically prevented as much as possible. But the way we think about the extent of the problem must be grounded in reality. Anything less is wrong too.

Written with Kenn Cukier. Also published on economist.com.

Image from here.