上海419论坛,上海龙凤419,爱上海 - Powered by Portia Eldi!

Keys to a split-second slime attack

first_imgThe velvet worm is a slow-moving, unassuming creature. With its soft body, probing antennae, and jointless legs, it looks like a slug on stilts as it creeps along damp logs in tropical climates.But it has a secret weapon. In the dark of night, when an unsuspecting cricket or termite crosses its path, the worm unleashes an instantaneous torrent of slime. Two fine jets of gluey substance spray out of openings on it head, casting a sticky net that entraps prey.Captivated, so to speak, by the worm’s split-second attack, researchers from the Harvard School of Engineering and Applied Sciences (SEAS) and from universities in Chile, Costa Rica, and Brazil began studying the creature from all angles. How, they wondered, could such a slow, neurologically simple worm execute such a rapid and perfectly aimed movement?By applying insights from anatomy, mathematics, experimental physics, and fluid dynamics, they now have an answer — published Tuesday in Nature Communications — and the findings could inspire new microfluidic devices.Imagine a large syringe equipped, at its narrow tip, with an elastic tube shaped like the neck of a bendy drinking straw. That is apparently the velvet worm’s slime-shooting apparatus, from its tail end — where the slime is produced and stored in a reservoir — to a pair of tiny nozzles, called papillae, on its head. Given this structure, a slow and gentle squeeze on the reservoir is all it takes to eject the slime with great speed and force. Most important, the shape and elasticity of the papillae ensure that as the slime exits, it sprays in all directions, like water from a flailing hose. Researchers are studying the velvet worm’s secret weapon – its ability to shoot two fine jets of gluey substance out of openings on it head, casting a sticky net that entraps prey instantly. Source: Cristiano Sampaio-Costa, Bernal Morera-Brenes, Julian Monge-Najera, Andres Concha “The geometry of the system allows the worm to squirt fast and cover a wide area. That’s the magic,” said lead author Andrés Concha, formerly a postdoctoral fellow at SEAS and now an assistant professor at Adolfo Ibañez University in Chile.But that’s not the whole story, as Concha explained. A garden hose is much larger than the tube inside a velvet worm’s papillae. To get the flailing-hose effect within such minuscule passages, with a diameter ranging from 50 to 200 microns, the worm relies on the elasticity and corrugated shape of its papillae. These features lower the threshold for tube-shaking fluid velocity.By identifying the features of the anatomy and material structure that enable the velvet worm to produce wide-spraying jets, the researchers have characterized a new type of flexible microfluidic system that they said could be used to produce fine droplets of liquid or fibrous nets, or to mix together several substances in laboratory or industrial settings.Concha and co-author Paula Mellado (also an assistant professor at Adolfo Ibañez University) were both Kavli Scholars at SEAS, studying topics relating to fluid dynamics, when the velvet worm project launched.“After watching the David Attenborough film ‘Life in the Undergrowth’ with some high-speed footage of the worm’s slime jet, I suggested that an elastic-hydrodynamic instability of the nozzle could be a simpler solution to creating a chaotic jet, rather than muscle control,” said co-author L. Mahadevan, the Lola England de Valpine Professor of Applied Mathematics at SEAS and a professor of organismic and evolutionary biology and of physics in the Faculty of Arts and Sciences. “Our work shows that this is indeed the case, and chalks up one more example of how evolution has co-opted a simple physical principle for a behavioral response.”The unusual velvet worms present a host of new questions for future research.“There are many cool properties of the glue that we need to explore,” Concha said. “If you put your fingers close to the mouth of the worm and you get some glue on your fingers, you wait seven seconds and you’re stuck. So one ambition is to be able to generate a synthetic glue like that, with biotechnological applications. I think there is some chemistry that we have to learn from the worm.”The diversity of the velvet worms, which make up the genus Onychophora, poses the question of how the squirting mechanism evolved to work across great variation in size.“That’s a great biological question,” Concha said. “By experience, we know that it works for all of these worms. Now, how they adapt the materials and the inner diameter of the hole inside the papillae, I don’t know. It’s very impressive. Even for babies, it works. You have a gigantic worm that’s eight or nine inches long and the baby is one inch, and already the mechanism is working.”While squirting mechanisms are common among animals, anything other than a straightforward arc of liquid typically requires an active movement and some degree of control. The range of approaches to that problem within the animal kingdom requires continued research.“Archer fish throw a jet of water, and it just follows a parabolic trajectory. Spitting cobras actively move their head to spray the poor fellow who is in front. And there are other cases — for example, spitting spiders — where the mechanism is unclear,” Concha said.As it happens, such apt, if venomous, study subjects are close to home in Chile.“Some biologists have posed the question, is this elasticity or is there any active mechanism? From what is in the literature up to now, I don’t have an answer, so spitting spiders are a nice thing to look forward to.”last_img read more

Derrick Davis & More Join The Phantom of the Opera Tour

first_img He will soon be bringing you the “music of the night!” Broadway favorite Derrick Davis will play the man behind the mask, The Phantom, in the national touring production of Andrew Lloyd Webber’s The Phantom of the Opera. He’ll join the show on October 20 when Phantom plays Bass Performance Hall in Fort Worth, TX.In addition to Davis, the cast of The Phantom of the Opera will soon feature Jordan Craig as Raoul, Trista Moldovan as Carlotta Giudicelli and Emily Ramirez as Meg Giry. They join current cast members Katie Travis as Christine Daaé, David Benoit as Monsieur Firmin, Price Waldman as Monsieur André, Anne Kanengeiser as Madame Giry and Phumzile Sojola as Ubaldo Piangi.Davis has been seen on Broadway as Mufasa and Scar in The Lion King, as well as on national tour. His additional stage credits include Dreamgirls, Show Boat, Amahl and the Night Visitors and Die Fledermaus.Following an acclaimed sell-out tour of the United Kingdom, Cameron Mackintosh’s spectacular new production of The Phantom of the Opera arrives in the U.S., featuring a brilliant new set and staging. The story centers on the thrilling love triangle between the mysterious Phantom, Christine and Raoul at the Opera Populaire in Paris. Lloyd Webber’s score includes the beloved songs “Music of the Night,” “Think of Me” and “All I Ask of You.”The production is directed by Laurence Connor with choreography by Scott Ambler, set design by Paul Brown, costumes by Maria Bjornson, lighting by Paule Constable and sound design by Mick Potter. Derrick Davis View Commentslast_img read more

Hancock County athletes win four indoor track events

first_imgORONO — Four Hancock County athletes won events at Saturday’s Eastern Maine Indoor Track League meet at the University of Maine’s New Balance Field House.Bucksport’s Mavis Taungatu’a, Danny Bunker and Johann Bradley as well as Ellsworth’s Tim Curtis all won events.Taungatu’a won the girls’ shot put with a distance of 36 feet and 3.75 inches; Bunker won the boys’ triple jump with 36 feet and 7 inches; Bradley, the boys’ pole vault with a height of 12 feet and 6 inches; and Curts, the boys’ shot put with 36 feet and 4.75 inches.Team scores are listed below.This is placeholder textThis is placeholder textBoys: Old Town, first with 136 points; Orono, second with 111; Hermon, third with 55; John Bapst, fourth with 51; Bucksport, fifth with 33; Ellsworth, sixth with 16; and Sumner, seventh with 15.Girls: Orono, first with 163 points; Old Town, second with 132; Hermon, third with 46; John Bapst, fourth with 30; Bucksport, fifth with 27; and Ellsworth, sixth with 25.View complete boys results here.View complete girls results here.Bucksport’s Danny Bunker won the boys’ triple jump at Saturday’s indoor track meet with a distance of 36 feet and 7 inches. ELLSWORTH AMERICAN PHOTO BY TAYLOR VORTHERMSEllsworth’s Mark Berry leads a pack of runners in the boys’ one-mile run at Saturday’s indoor track meet. Berry placed fifth with a time of five minutes and 30.4 seconds. ELLSWORTH AMERICAN PHOTO BY TAYLOR VORTHERMSA Sumner runner sprints for the finish line in the girls’ 55-meter dash at Saturday’s indoor track meet. ELLSWORTH AMERICAN PHOTO BY TAYLOR VORTHERMSBucksport’s Johann Bradley sprints for the finish line in the boys’ 55-meter dash. Bradley took third in 7.29 seconds. ELLSWORTH AMERICAN PHOTO BY TAYLOR VORTHERMSlast_img read more