Wednesday, October 27, 2010

Ball 15. Fish Whispers

Rolf Korneliussen listens to fish. The Norse acoustician has been studying ways of using sound waves to identify fish species deep below the ocean surface. His research has shown that it’s possible to catalog telltale echo signatures, basically acoustic fingerprints, of species such as mackerel, capelin, squid and Norway pout.

Although even a weekend angler’s 14-footer can be rigged with a fish finder, the relatively crude sonar technology does little more than reflect the presence of a moving thing below the boat—possibly a fish, but not necessarily. More sophisticated sonar devices have had somewhat better luck identifying individual species, although they are far from reliable.

As a result, sonar has been of limited use to marine biologists concerned with monitoring vast—or, as the case may be, dwindling—stocks of critical ocean species like mackerel, herring and cod.

Korneliussen’s software relies on a technology called frequency-dependent backscatter—the reflection of sound waves in their direction of origin—as the main method for identifying fish species underwater. To improve the accuracy, it also incorporates measures of backscattering strength, geographical position, school-shape and other details that can be unique to particular species.

Korneliussen, of the Institute of Marine Research in Bergen, said the system

can be trained to identify several species. Currently our identification library contains Atlantic mackerel, herring, capelin, southern krill, northern krill, sand-eel and squid

However, he added, for some species the technique remains less definitive than it is for mackerel.

For the moment, the acoustic technology is best suited to scientific research, as it requires calibrated echosounders, but it has significant implications for the commercial fishing industry, Korneliussen said.

In Norwegian waters, any fish that is caught has to be delivered on land, so catching the wrong species—or catching a species at the wrong time of year—could cost quite a bit in lost income.

However, he added,

the scientific software has been modified to fit the commercial fishing fleet since we feel obligated to make new scientific methods available to them, but the software is currently not ready for general use by fishermen.

Korneliussen reported his latest findings in the ICES Journal of Marine Science.

Wednesday, October 13, 2010

Ball 14. When Pool Filters Attack

"Life," Woody Allen once quipped, "is divided into the horrible and the miserable." He clearly didn't spend a lot of time on Pubmed, else he would have come up with a third category to explain this:

"Swimming pool filter-induced transrectal evisceration in children: Australian experience."

The article comments on a case series reported last May in the Medical Journal of Australia of this terrible (and, in all seriousness, terribly traumatic for the victim) event that, unlike a lot of other medical conditions requires no translation.

"the long-term functional outcomes in the three cases of swimming pool filter-induced transrectal evisceration described by Price and colleagues are excellent and significantly better than many other cases described in the literature."

Many other cases described in the literature? How many cases of pool filters attacking Down Under could there be?

Quite a few, it seems. Reports of similar incidents date back 1982, and, while sporadic, aren't difficult to find. At least one myth-debunking site, Stupid People Tricks, describes a case in North Carolina while dispelling the similarly gruesome, but apparently apocryphal, stories of intestinal misadventures in airplane lavatories. (The lawyer in that case? A young John Edwards, who won millions of dollars for the family of the young girl injured in the episode.)

The lesson is simple: Pools are attractive nuisances and no matter how high the fence, they're always a threat. Anyone who owns one should exercise the utmost caution to avoid injury.

Well, okay, that's a lesson, I guess, but another message is that the human body truly is an amazing thing: No matter how obscure the mechanical invention, we'll find a way to let it maim or kill us.

(Disclaimer: I didn't pitch this as a story ... yet.)