Whip it good: how flagella help cells move

The linked article is for SIAM News, the magazine for members of the Society for Industrial and Applied Mathematics (SIAM). However, even though the main audience for this magazine is professional mathematicians, I wrote it to be understandable even if you gloss over the math.

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A Mathematical Tale of Fibers, Fluids, and Flagella

For SIAM News:

Under a microscope, a cell scoots along by its own power and hoovers up small crumbs of nutrition from the water around it. An example of such an organism is a choanoflagellate, which has a thin, whip-like appendage called a flagellum that controls its feeding and motion. While similarly proportioned apparatuses would be useless on a human scale, flagella are common among single-celled organisms like bacteria, the sometimes-toxic dinoflagellate algae, and even human sperm cells.

Motion in the microscopic world—particularly in fluids—involves an entirely different set of forces than those that govern macroscopic environments. Flagella operate efficiently under these forces and allow microscopic life to move around in fluids, where large viscous forces are present even in substances such as water. The motion of choanoflagellates and the way in which flexible fibers or strands of cells passively respond to liquid flow all constitute a set of complex problems with many potential applications in engineering and medicine.

“With the advent of microfluidic devices and computational technology, there has been an incredible resurgence in studies of the flow of tiny creatures at the microscale,” Lisa Fauci, an applied mathematician at Tulane University and a former president of SIAM, said. “There are possibilities of creating nanorobots that can be guided with external magnetic fields to break up blood clots or deliver drugs to a tumor.”

Read the rest at SIAM News


Using math to understand why species don’t out-eat each other

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This article is a little different from the fare you’re used to getting from me: it’s for SIAM News, which is the glossy magazine for members of the Society for Industrial and Applied Mathematics (SIAM). The audience for this magazine, in other words, is professional mathematicians and related researchers working in a wide variety of fields. While the article contains equations, I wrote it to be understandable even if you skip over the math.

Competitive Adaptation Prevents Species from Eradicating Each Other

For SIAM News:

Evolution is frequently rough and unforgiving; individuals within a species compete for food, reproductive partners, or other resources. Species fight each other for survival, especially when preying on one another.

Mathematical biologists often simplify these dynamics to predator versus prey. Real-world populations of predator and prey species within a given ecosystem cycle between booms and busts. In various cases, multiple species—including both predators and prey—coexist with similar diets. For example, a cubic meter of seawater can harbor several species of plankton, consisting of tiny plants and animals (see Figure 1).

One would naively expect reproductive success (more offspring) or competitive performance (eating more than your neighbor) to lead to one species’ domination. But that does not occur. While many of these organisms consume the same food, one species does not out-eat the others; the plankton swarm’s overall diversity remains fairly constant. Biologists refer to this phenomenon as the “paradox of the plankton” or the “biodiversity paradox,” among similar terms.

[read the rest at SIAM News]

Snakebots, desert plants, and self-assembling space modules: the world of biomimicry

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“Life, uh, finds a way”—Applying lessons from evolution to go to Mars

Biomimicry looks to living organisms to create the future of sustainable engineering.

A robot designed to move like a sidewinder snake, from Henry Astley’s lab at the University of Akron. [Credit: moi]

For Ars Technica:

As philosopher-mathematician Jeff Goldblum once said, “life, uh, finds a way.”

To phrase that more scientifically, evolution has had billions of years of trial and error to produce species that are well adapted chemically and physically. Many human researchers want to imitate that adaptation, turning lessons from the natural world into practice in engineering, technology, and architecture. The entire venture goes under the name “biomimicry.”

“I think biomimicry is really beautiful,” says Ariel Ekblaw, a student at MIT’s Media Lab, who founded and leads the Media Lab’s Space Exploration Initiative. “It’s both a framework and… a set of tools or learnings from nature that can inform modern engineering and science research projects.”

To see the spectrum of biomimicry research, I attended a three-day workshop called “Nature-Inspired Exploration for Aerospace.” The workshop was cosponsored by NASA’s Glenn Research Center, the Ohio Aerospace Institute, and Great Lakes Biomimicry. Despite the aerospace focus, the program ranged from straight-up biology to philosophical queries about the reasons for doing biomimicry in the first place.

[Read the rest at Ars Technica]

City ant, country ant, and climate change

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Acorn ants as seen through a microscope. [Credit: moi]

I know, I know: it’s been a long time since I last had something published. This is largely because I took a little time off to finish my novel. With the first draft done, I needed to catch up. As a result, I have six or seven (depending on how you count) articles that are finished, but which won’t be published immediately. Anyway, here’s the first of those, published today:

What City Ants Can Teach Us About Species Evolution And Climate Change

Is the rapid evolution of a certain ant species to urban environments a preview of life on a warming planet? Some researchers are trying to find out.

For Undark Magazine:

Acorn ants are tiny. They’re not the ants you’d notice marching across your kitchen or swarming around sidewalk cracks, but the species is common across eastern North America. In particular, acorn ants live anywhere you find oak or hickory trees: both in forests and in the hearts of cities.

That’s why they’re so interesting to Sarah Diamond, a biology professor at Case Western Reserve University in Cleveland. “We’re comparing this little forest island within a city to traditional forest habitats,” she says. Specifically, she and her colleagues are looking at how well city ants can tolerate higher temperatures compared to their rural cousins. The experiment is made possible by what’s known as the urban heat island effect, which describes the tendency of the built-up infrastructure of cities — think heat-absorbing concrete and asphalt, for example — to create a hotter environment than less developed areas. [read the rest at Undark Magazine]

Evolution, entropy, and beards

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The Hidden Connections Between Darwin and the Physicist Who Championed Entropy

These magnificently bearded men both introduced a dose of randomness and irreversibility into the universe

For Smithsonian Magazine:

Of all the scientific advances, evolution has been the hardest on the human ego. Charles Darwin’s revolutionary theory, laid out in his groundbreaking 1859 book On the Origin of Species, threatened to overturn humanity’s exalted position in the universe. Yet in the same era, a quieter—and seemingly unrelated—scientific revolution was also taking place.

The concept of entropy in physics began harmlessly enough, as an explanation for why steam engines could never be perfectly efficient. But ultimately, entropy also threatened an established hierarchy. And in fact, entropy and evolution were more than casually related. [Read the rest at Smithsonian]

We aren’t the dinosaurs: we’re the asteroid

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The Sixth Extinction: We’re Not The Dinosaurs, We’re The Asteroid

Yes, humans are probably to blame for the Earth’s sixth mass extinction event, which is wiping out species at a rate 53 times greater than normal.

For The Daily Beast:

Extinction is an inevitable consequence of evolution. Environments change, new species arrive and crowd out the old, any number of factors make a formerly successful species unsuccessful. No less an authority than Charles Darwin wrote in The Origin of Species, “Natural Selection almost inevitably causes much Extinction of the less improved forms of life and induces what I have called Divergence of Character.”

Even without the 19th-century capitalization for emphasis, extinction is a big deal. Earth has experienced at least five major mass extinction events, of which the end of the dinosaurs wasn’t even the largest. (The end of the dinos that hadn’t evolved into birds, of course.) Now the planet is experiencing the sixth mass extinction, and growing evidence points to the culprit. It’s not asteroids or volcanoes or methane this time.

It’s us. [Read the rest at The Daily Beast….]

My review of Brian Switek’s forthcoming book, My Beloved Brontosaurus, is up at Double X Science!

Suffice to say, these are not the dinosaurs I learned about as a young kid—and in my opinion, they’re much more interesting. Over the last few decades, the basic realization that modern birds are living dinosaurs has grown, and helped us understand their extinct uncles and aunts: the dinosaurs of the distant past. (Many scientists even refer to the classic dinosaurs as the non-avian dinosaurs, meaning these are the ones that aren’t recognizably modern birds.) For example, hollow yet sturdy bones allow modern birds to fly, but they also allowed sauropods to grow into the biggest animals ever to live on land. We also know now, thanks to a number of recent finds, that probably every dinosaur lineage had feathers of some sort. As Switek wrote, “Just think of how cute a fuzzy little Apatosaurus juvenile would be.” I concur. [Read more…]

Dinosaurs belong to all of us

I take it personally when idiot politicians call me and my fellow scientists evil liars. My latest post at Galileo’s Pendulum explains why:

Broun and his compatriots obviously think very bad things about me, my friends, and the work we do. They don’t just disagree or think we’re wrong, they think we’re literally in league with Satan. The work we do—researching, writing, and teaching others about how the Universe works—is evil in their eyes. Broun’s explicit statements that science education is all built on lies aren’t harmless. I hold education to be one of the most noble undertakings in human society, and here we have an elected official trumpeting ignorance while slandering those who work to knowledge. [Read more….]

You may hate me, but don’t spread your lies to children