Monthly Archives: January 2010

Slime Mold, Network Designer

In an experiment reported in the New York Times on Tuesday (Jan 26), slime mold uses design principles very close to those devised by humans. The slime mold is a unicellular being that spreads itself out in search of food and then links to food sources via tiny tubes. In the experiment, researchers placed food sources at the some position relative to the slime mold as the surrounding cities are to Tokyo. Within 24 hours, the slime mold had linked the food sources in a pattern similar to that of rail links among Tokyo and nearby cities. Reporter Henry Fountain writes, “The researchers found that the slime mold network was as efficient as the rail network, it tolerated breaks in the connections just as well, and it was created at reasonable cost to the organism.” The image at left, copied from the paper, shows the mold (yellow blob), food sources (white dots), and tubular connections (thin white lines) at 0, 5, 8, 11, 16, and 26 hours of activity.  This is considerably less time than it took engineers to design the railway system. Scientists have already created a mathematical model to replicate the simple steps–call them algorithms–that lead the slime mold to create this kind of pattern. How similar are human networks?

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Zero Emissions House

Invited by a solar installer I met last fall, I took two friends to an open house for a zero emissions house in Portsmouth, NH. Designed by the house’s owner, who also served as developer and general contractor, the house sits on a sweet little piece of land on the North Mill Pond, a tidal body of water. It rests on a foundation of crushed stone and a thick layer of foam; the floors are all tinted poured concrete. The walls are 2 x 6  framed two feet on center to reduce the number of uninsulated points. Once in place, the framed was covered in plywood, sealed up, and painted with an adhesive paint to which four inches of foam were added before the exterior cladding.  The rate of air exchange is extremely low–1.6 changes per hour, meaning that it is extremely tight. The day was cold and windy but the house was warm. The room on the house’s right is a greenhouse with cherry tomatoes, chard, and baby lettuce in full flourish. On the roof is a fairly large solar array (black) and to its left a smaller solar thermal unit that heats hot water. The whole house is kept warm by the occasional use of a little propane-run fireplace thing.

Top Ten Reasons to Live in New Hampshire

1. Eighteen miles of coastline. Yes, it’s cold and kind of grey. It’s the Atlantic, dammit.

2. Mount Washington. Fiercest winds on Earth.

3. Gay marriage. Yes! Beginning January 1.

4. Presidential primary. Get a close look at future presidents and also-rans.

5. License plate: Live free or die. Not to be taken literally.

6. No sales tax. Shop here for bargains.

7. Lakes and rivers. Lots of water here; no droughts likely. Floods, yes.

8. Oldest family farm in America–Tuttle’s Red Barn, in Dover.

9. Women control the state senate; it’s first legislative body in the country to have more women than men.

10. Robert Frost wrote a poem about it.