Geek stuff – Page 123 – a sibilant intake of breath

Salmon farming and sea lice

Recent work by Martin Krkosek of the University of Alberta has demonstrated strong links between the practice of salmon aquaculture and the incidence of sea lice infestations that threaten wild populations. One study used mathematically coupled datasets on the transmission of sea lice (Lepeophtheirus salmonis) on migratory pink (Oncorhynchus gorbuscha) and chum (Oncorhynchus keta) salmon. They concluded that:

Farm-origin lice induced 9–95% mortality in several sympatric wild juvenile pink and chum salmon populations. The epizootics arise through a mechanism that is new to our understanding of emerging infectious diseases: fish farms undermine a functional role of host migration in protecting juvenile hosts from parasites associated with adult hosts. Although the migratory life cycles of Pacific salmon naturally separate adults from juveniles, fish farms provide L. salmonis novel access to juvenile hosts, in this case raising infection rates for at least the first 2.5 months of the salmon’s marine life (80 km of the migration route).

Packing fish together in pens that are open to the sea is an almost ideal mechanism for breeding and distributing parasites and disease. In nature, you would never find salmon packed 25,000 to an acre. Keeping them in such conditions – and making them grow as quickly as possible – generally requires chemical manipulation. The earlier discussion here about antibiotic use and its role in the emergence of resistant bacteria is relevant.

These concerns also exist in addition to the fundamental reason for which fish farming cannot be sustainable: it relies on catching smaller and less tasty fish to feed to the tastier carnivorous fish that people enjoy. It thus lets us strip the sea bare of salmon or cod or trout and compensate for some period of time by using cheaper fish as a factor for their intensive production. Given that those cheaper fish are caught unsustainably, however, fish farming simply delays the emergence of truly empty oceans. And the industry is trying to have farmed salmon labelled ‘organic.’ Ludicrous.

Source: Krkosek, Martin et al. “Epizootics of wild fish induced by farm fish.” Proceedings of the National Association of Sciences. October 17, 2006, vol. 103, no. 42, 15506-15510.

P.S. Shifting Baselines also has some commentary on sea lice and salmon farming.

Rejecting Canada’s new copyright act

As a student, I was constantly being called upon to support various causes, through means ranging from making donations to attending rallies. Usually, such activities have a very indirect effect; sometimes, they cannot be reasonably expected to have any effect at all. Not so, recent protest activities around Canada’s new copyright act: a draconian piece of legislation that would have criminalized all sorts of things that people have legitimate rights to do, such as copying a CD they own onto an iPod they own.

Defending the fair use of intellectual property has become a rallying point for those who don’t want to see the best fruits of the information revolution destroyed by corporate greed or ham-fisted lawmaking in the vein of the much-derided American Digital Millennium Copyright Act. At their most controversial, such acts criminalize even talking about ways to circumvent copyright-enforcement technology, even when such technology is being mistakenly applied to non-copyrighted sources: such as those covered by the excellent Creative Commons initiative or those where fair use is permissive for consumers. Watching a DVD you own using a non-approved operating system (like Linux) could become a criminal offence.

For now, the protests seem to have been successful. Of course, the temptation for anyone trying to pass a controversial law is to hold off until attention dissipates, then pass it when relatively few people are watching. Hopefully, that will not prove the ultimate consequence of this welcome tactical victory for consumer rights.

Entertaining physics demonstrations

His name is Julius Sumner Miller and physics is his business.

For those who lacked my good fortune in seeing most of these demonstrations a number of times at Vancouver’s Science World, the videos should give a sense of how physics can be made universally comprehensible and exciting. The facts that Mr. Miller looks like a mad scientist and that he has a penchant for hyperbole may well contribute to his ability to hold one’s attention.

My involvement as a camper and leader at SFU’s Science Alive daycamp also impressed upon me the effectiveness of physical demonstrations in sparking children’s interest in science. That is especially true when the demonstrations involve rapid projectile motion, strong magnets, cryogenic materials, aggressive combustion, and explosions.

Geminid meteor shower

Those of you with clear skies should make a point of peering at them tonight. The shower – produced by debris from a near-Earth asteroid called 3200 Phaethon – should become increasingly intense throughout the night, peaking in intensity around dawn. According to NASA, this should be the best meteor shower of the year. It may well be worth getting up before dawn (or staying up especially late) and looking to the western sky.

3200 Phaethon is thought to be a former comet, dust from which began intercepting Earth’s orbit annually during the American Civil War. The object is about 5 kilometres wide and misses the earth by only 2 million kilometres. If you have access to a decent telescope (many university observatories are open to the public some nights), you can observer Phaethon in the constellation Virgo. It only has the brightness of a 14th magnitude star, so neither the naked eye nor binoculars are sufficient to pick it out.

iBook dead

After running a routine maintenance script, my iBook has decided that it no longer wishes to perform any of the functions traditionally associated with a computer. It will probably be a few days before I am up and running again, during which time I will be unable to check my personal email.

Given that I will probably have to wipe my hard drive and start over, it makes sense to pick up a copy of the new release of Mac OS before I do so.

Back in a few days.

[Update: 2:37am] After $100 and seven hours of backing up, formatting, and installation, the computer is healthy enough to access the web – and running Leopard to boot. The lengthy task of bringing back all my data and applications will need to wait for a later time.

[Update: 12 December 2007] It seems having byte-for-byte backups of data held in Apple software is not terribly useful. I can import my 14,000 image files back into iPhoto easily enough (though it takes six hours), but they lose all the information I have spent dozens of hours entering: locations where they were taken, who is in them, whether they have been used as blog photos, etc. This whole recovery process has me tearing out my hair in frustration, while spending six hours or more each night working on it.

Materialism

The terms ‘materialism’ and ‘materialist’ seem to be popularly misunderstood. As such, it bears mentioning that there are two wildly different interpretations of what these terms mean.

Perhaps the more common interpretation is based around a desire for material possessions. In this view, a ‘materialist’ is someone who continually wants to own more things.

A much more interesting definition holds that being a ‘materialist’ means that you believe everything in the universe is made of comprehensible materials, interacting with each other on the basis of laws we can understand. This viewpoint definitely raises important questions in philosophy – and potentially lethal ones in theology – it is also much more worthy of consideration than the fact that neighbour X might want a bigger car than neighbour Y.

AXA lock flaw

In a situation somewhat similar to the bump key vulnerability, another serious mechanical lock flaw has been found, this one affecting a popular kind of Dutch bicycle lock.

I found this by means of an interesting blog about mechanical locks.

200 million pieces of Pi

Pi – the ratio of the circumference of a circle to its diameter – is an irrational number, meaning its decimal expansion never ends or repeats. As such, it could never be written out in full. If Pi is also a normal number, roughly meaning that the value of an arbitrary digit is random, an interesting property arises. Specifically, that every possible string of digits will be located in it somewhere. Given that any text can be perfectly converted into a number and any image or sound can be very well approximated by a number, this means that every possible written document, painting, photograph, symphony, and lecture can conceivably be located somewhere within that endless string of digits.

Quite a while ago, I had the idea that you could refer to any information in terms of a ‘Pi address’ – where to look within Pi to find the desired data. It would work for anything from the newest Tori Amos album to the first edition of the Oxford English Dictionary. The biggest problem is that the address would, in most cases, require more storage space than the actual data.

This website proves the point by letting you search the first 200 million digits of Pi for any string you want. My birthday begins at digit 196,469,286; my office phone number begins at digit 124,573,291. Because it is mathematically possible to calculate Pi from any arbitrary decimal place, it isn’t necessary to find all the prior digits to convert those back into the numbers they represent. That said, for large pieces of data (like the book and album mentioned), the Pi address would almost certainly be a lot longer than a data file containing the entire work. Pi addresses may not be a good way to refer to information, though they do provide a relatively dramatic perspective on the nature of infinity.

Strong nuclear force, weak nuclear force, gravity, and…

In the mail today, I got some neodymium magnets from my brother Sasha as a birthday gift. They are good fun – largely because of how fundamentally counterintuitive magnetism is. Is just seems odd that things are repelled and drawn together by an invisible force that manifests itself at short distances. The danger to nearby magnetic stripe cards and hard drives is trivial when compared to their enjoyment potential.

The only downside of nickel-plated rare earth magnets is their tendency to snap together violently if you aren’t quite careful. Given how brittle they are, this can send tiny shards flying in all directions. This afternoon’s messing about only had one casualty – one of the four smallest magnets among the fifty found its way between the two largest. The larger fragments of the small magnet are now holding papers to my filing cabinet.

On the plus side, I have worked out how to build a reasonably effective magnetic canon using most of the magnets in the set and the barrel from a Bic four-colour pen. It is also trivially easy to make a compass using all fifty magnets in a line, hanging from a piece of floss.

One day, I want to get a full-sized, absurdly powerful supermagnet of the kind at the bottom of this page. At $50 to $275 apiece, they may have the lowest cost-to-danger ratio of anything you can buy online.

Problems with government databases

By now, everyone has probably heard about the data loss debacle in the United Kingdom. The British government lost the child benefit records for 25 million people. These records include addresses, dates of birth, bank account information, and national insurance numbers. In total, 40% of the British population has been exposed to the risk of identity theft.

Obviously, this should never have happened. One government agency requested some anonymized data for statistical purposes. Instead, a different department sent them the whole dataset in an unencrypted format. Encrypting the discs would have made it nearly impossible for thieves to access the data; anonymizing the data would have made such theft unprofitable. The failure to do either is the height of idiocy, but it is probably what we need to expect from the civilian parts of government when it comes to data security. Security is hard; it requires clever people with good training, and it requires oversight to ensure that insiders are competent and not cheating. People who are naive and naturally helpful can always be exploited by attackers.

In response to this situation, two sets of things need to be done. The first is to correct the specific failures that cause this kind of problem: require encryption of sensitive documents in transit, limit who has access to such sensitive databases, and tighten the procedures surrounding their use. The second is to limit the amount of such data that is available to steal in the first place. That could involve using paper records instead of digital ones – making mass theft dramatically harder to accomplish. It may also involve not creating these kinds of huge databases, as useful as they may seem when working properly.

It is fair to say that there will always be people out there able to break into any information that a large number of civil servants have access to. This would be true even if all civil servants were capable and virtuous people, because a lot of the best computer talent is applied to breaking flawed security systems. Given that bureaucrats are human, and thus subject to greed and manipulation, the prospects for keeping a lid on government data are even worse. Acknowledging the realities of the world, as well as the principle of defence in depth, suggests that limiting the volume of data collected and held by all governments is an appropriate response to the general security risks highlighted by this specific incident.