Last year, Patty Brennan and I were part of the SciFund Challenge – an experiment in crowdfunding scientific research that raised over $75,000 for its projects in just 45 days. RocketHub, our hosting platform, clearly took note: it added “Science” to its overall list of project categories, so appeals to support dance, music or photography will now sit alongside requests to fund projects in plant genetics or primatology. And I was delighted to learn that one of the first scientists to step up to the plate is doing some fantastic functional morphology.
He’s already raised enough cash to fund his experiments in South Africa, but further donations will let him take the study to other countries. His RocketHub link is <here>, and there's still a couple of weeks left to donate.
I just learned that one of my photomicrographs has been chosen for the Science Art show at this year’s Science Online conference in Raleigh. Here it is:
Milligan’s Trichrome stain gives this thin slice of alligator tissue the look of a stained-glass window, with scarlet strips of smooth muscle interspersed between bands of blue collagen fibers.
Assembly was remarkably fast: it took me less than 30 minutes. The kit really does just snap together – no glue, no sanding, no prep beyond peeling protective paper off each side of the plywood pieces. The peeling is necessary -- the tolerances of the laser-cut pieces are so tight that the kit’s tabs won’t go through its slots until the paper is removed – but the end result is a model without any wobble or shimmy. The trickiest part was threading the thin string through the tiny holes in the sling, and that’s more of a comment on my middle-aged eyes than anything else.
The kit comes with a pair of superballs as ammo. I used one for the inaugaral throw. Foolishly. Inside the house. I didn’t break anything, but we’re still looking for one of the balls. After that, we switched to crumpled balls of paper and were consistently shooting them 30 feet across the room. Our cat now thinks we bought the treb for her. You can order one for your very own at siegetoys.com.
Our last CSA share of the year contained a lovely surprise – three ears of popcorn, still on the cob. My kids were excited, because although our CSA also gives us a bountiful share of sweet corn in August, popcorn is much less like a vegetable. After all, most vegetables don’t explode.
Superficially, sweet corn and popcorn kernels look the same. But even if I’d taken the time to dry out some of that pile of sweet corn in my kitchen back in August, we’d only get a bunch of funny-smelling toasted kernels if we tried to pop it. Popcorn can explode because it has two things that sweet corn does not: a lot of hard starch in its center and a thick outer covering.
We can eat sweet corn kernels without breaking or grinding them first because they have a thin hull – it’s thick enough to provide a little snap when you bite through it, but not thick enough to break your teeth. You wouldn’t want to try that with popcorn. At least, my dentist doesn’t recommend it. But that tooth-cracking hull makes a dandy pressure cooker.
Put a bunch of popcorn into hot oil or air, and the starch and water inside the kernels heat up. As the temperature passes 100°C, the water starts to boil and turn to steam, but the hull keeps the steam from expanding and the pressure inside the kernel starts to climb. As superheated steam permeates starches in the kernel they soften and expand, raising the internal pressure even higher. By the time the temperature inside a kernel reachs 177°C, the liquids inside it are seething at pressures nine times higher than atmospheric pressure. If that weren’t bad enough, the heat also starts to melt and weaken the kernel wall. Soon, the kernel can’t hold back the maelstrom – its wall ruptures, releasing a tiny cloud of superheated steam and starch.
The amount of moisture in the kernel is critical: too little, and there’s not enough steam to break open the kernel. Too much, and the kernel wall melts and ruptures before the pressure climbs high enough to puff out the starch. (Those unpopped kernels at the bottom of the bowl? Probably lost too much moisture in storage.)
Once the kernel is open, the pressure of the starch cloud drops, and the rapidly expanding steam carries a film of starch outward. The type of starch inside the kernel determines how far the puff expands: hard starches stretch farther than soft ones. As the cloud expands, it cools until the starch sets into the shape of a miniature explosion – a puff that can soak up butter without collapsing or hold up a layer of hot sugar. Just the thing for a cold winter’s night.
Graph from Gökmen, 2004.
References:
Gökmen, Sabri 2004. Effects of moisture content and popping method on popping characteristics of popcorn. Journal of Food Engineering 65: 357–362
Hoseneya, R. C., K. Zeleznaka and A. Abdelrahmana 1983. Mechanism of popcorn popping. Journal of Cereal Science 1(1): 43-52.
McGee, H. 2004. On Food and Cooking, 2nd edition. Scribner: New York.
I know we used to post a lot. Jim and I were coming back to you again and again to share our observations about science: I’d describe the journal article I’d just read, Jim would chime in with snarky comments about new tech. But lately, we’re just not stopping by as often, and when we do we’re far more likely to leave a 150-word calling card than to stay for a 1000 word visit. Do you feel abandoned? I don’t blame you.
No, it’s not you. Jim and I are as fond of you as ever. Time is just a commodity we’re short on these days, and when we actually have some to spare we’re usually too exhausted to put together a coherent string of words. You see, I’ve spent the past year doing neuroscience research on an NIH fellowship. And since I knew next to nothing about neuroscience when I started, I’ve spent a lot of time feeling like my brain was going to explode from the pressure of the new information I’m cramming into it. I’m finally getting some great data, but (and I’m sorry about this) I can’t share it with you until it goes through peer review. Early on I thought I might be able to squeeze a visit in at lunchtime, but then I got tapped for a committee and that slot vanished. I know that Jim had all sorts of good intentions about picking up the slack by stopping by to visit more often, maybe bring a cake, but he’s been writing a novel. That’s surprisingly time-consuming, too.
I can’t say that our workload is going to ease up anytime soon, but I do want to get together again regularly. There are a lot of interesting citizen science projects popping up that I want to chew over with you, and my file of journal articles to share is bulging at the seams. It may not be the newest news, but I guarantee that it’ll be interesting. So, are you free for coffee next week?
A fish out of water flops – everyone knows that. But while most fish flail in place when they’ve got no water to push on, a few species can flip into a controlled long jump that sends them flying several times their body length in one direction. How far can these fish jump? Take a look at this mosquitofish (Gambusia affinis) in flight.
Pretty cool, eh? Understanding that jump is the subject of a paper published today in the Journal of Experimental Zoology by Alice Gibb, Miriam Ashley-Ross, Cinnamon Pace, and my former grad school officemate John Long. They noticed that these jumps looked a lot like the movements a swimming fish makes to escape predators – called a “c-start” for the characteristic letter-shape the fish bends into – and they figured that the fish were co-opting their aquatic escape behavior for moving efficiently on land. But when they looked more closely, they found that there were some important differences.
For one, on land, the fish don’t bend their tail and head toward the middle of the body evenly as they would in a watery c-start. Instead, they swing head toward tail, bending the body in a sharp curve before a push from the tail launches the fish into the air. The difference seems small, but it implies that the fish are using the same set of muscles differently on land and underwater. So if one of these fish gets stranded on land, the same muscles that produce a rapid-fire snap-and-dart in the water can shift to a slower rhythm that gives the fish a better chance of getting back in the water.
Remember yesterday’s movie of the toad eating in slow motion? Now watch this one. It’s still a toad eating a cricket, but this time it was filmed at two different temperatures. Keep two things in mind – first, the toad’s body temperature is the same as the air around it, and second, muscle works faster when it’s warm. That’s why it takes a lot longer for the toad to pull its tongue into its mouth and close its mouth at 17°C than at 24°C. But there’s no real difference in the time it takes to for the toad to fling its tongue out of its mouth. That’s because tongue extension is powered by elastic recoil. Slow muscle contractions pull elastic tissues inside the tongue tight while the toad’s mouth is still closed. When it opens, the tongue flies forward like an arrow from a bow. So whether it's hot or cold, the toad's always ready to go hunting.
There's lots of interesting biomechanics going on in this short high-speed video of a toad eating a cricket. For example, watch the tongue elongate from its own inertia as it whips out of the toad's mouth. And see how the toad's eyes start to close as it swallows the cricket at the end of the film? That's not satisfaction -- it's using its eyes to help shove the food down its throat.
A few years ago, we designed a card game inspired by the outrageous antics of 19th century American paleontologists. This week, WGBH's debuts a new documentary on the same subject: you can watch Dinosaur Wars when your local PBS affiliate broadcasts it later this week, or stream it right now on the American Experience website. Clearly, scientists behaving badly are a great subject for drama.
Diane A. Kelly Diane Kelly is a Senior Research Fellow at the University of Massachusetts, Amherst, where she studies the neural wiring and mechanical engineering of reproductive systems.
James L. Cambias Jim Cambias writes science fiction and designs games in the lonely wilderness of Western Massachusetts.
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