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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

The rent-proof southeast QLD suburbs buyers should invest in

first_imgThe bayside suburb of Thornlands in the Redland Shire has a mix of waterfront and rural residential properties.“There is something for everyone in Thornlands, including comprehensive retail facilities andeasy access to the Cleveland town centre,” Mr Crabb said.“Owner occupiers make up 74 per cent of housing, and median household income sits at ahealthy $1936 per week.Mr Crabb said hospital workers and primary school educators made up a large proportion of residents. Thornlands SOUTHEAST QLD’S RENT-RESILIENT SUBURBS The Gold Coast suburb of Arundel is close to the beach and major highways, as well as having an abundance of schools and shopping facilities.“ABS numbers show Arundel has a high proportion of medical industry workers, with strongmedian rent at $400 per week,” Mr Crabb said.“Given that detached owner occupier homes achieve such good prices, we believe there’san opportunity for investors to purchase price-accessible stock in new developments thatsee strong tenant demand.” West of Brisbane and close to Ipswich, Karalee has a ‘rural village’ appeal combinedwith major-city amenities.“The location itself is extraordinary with river frontage and bushland features throughout, butcomprehensive local amenities as well as the short drive to the Ipswich CBD means you areMore from newsParks and wildlife the new lust-haves post coronavirus9 hours agoNoosa’s best beachfront penthouse is about to hit the market9 hours agonever far from necessary services,” Mr Crabb said.“Statistics show hospitals are a major employer of Karalee residents, and the averagehousehold income of $2408 per week is over $1000 per week higher than the Queensland“I also note owner occupiers make up 84 per cent of households which means there’s soliddemand from long-term residents.”The median weekly rent in Karalee is $450. Houses in Karalee, near Ipswich. Newport Bridgeman Downs East Brisbane $663 26% Bulimba $625 26%Cleveland $565 26% Paddington $508 21%Norman Park $595 20% Ashgrove $455 15%Kedron $538 19% Coolangatta $480 14%Dakabin $400 14% Everton Park $425 12%(Source: Realestate.com.au) According to Aspire’s research, Bridgeman Downs, in Brisbane’s middle north, has a median weekly rent of $450 — well above the state average.“This location has been a real sleeper,” Mr Crabb said.“As a traditional homeowner’s location, not many investors have purchased here in the past.”Census data reveals 30 per cent of Bridgeman Down residents are educated to BachelorDegree level, while hospitals and GP medical services are the dominant industries of occupation. Household income is 70 per cent higher than the state average, and 85 per centof residents are owner occupiers.“This tells us that the suburb appeals to professionals with stable job prospects, goodincomes and strong educational backgrounds. It also shows there is strong owner-occupierdemand, meaning the market isn’t subject to investor-level downturns,” Mr Crabb said.“I know of one townhouse project where they’ve been achieving sale prices of $530,000,which have been readily renting for $530 per week That’s a five per cent gross return duringthe lowest interest rate environment in living memory.” This house at 4 Outlook Crescent, Bridgeman Downs, is for sale. Karaleecenter_img Arundel Rents have risen in some southeast Queensland suburbs in the past month.INVESTORS are being urged to cash in on southeast Queensland’s rent-resilient suburbs, where rentals are in demand and tenants are prepared to pay top dollar.Realestate.com.au has crunched the numbers and released a list of the suburbs that have recorded a rise in rent over the past month, despite fears over increasing vacancy rates and falling rents due to COVID-19.Rents for houses have jumped more than 20 per cent in East Brisbane, Norman Park and Cleveland, while landlords can expect to pocket an average $625 a week from leasing a unit in Bulimba. This house at 27 Agnew St, Norman Park, is for sale.Realestate.com.au chief economist Nerida Conisbee said the increases in rents for some southeast Queensland suburbs in the past month showed well located, good quality properties would always be good investments.“The fact asking rents are increasing at that rate during a significant problem in the economy is pretty amazing,” Ms Conisbee said.“Most of these suburbs are in pretty nice locations. “If you’re buying an investment property, buy somewhere that you would want to live and something you’d want to live in.” This house at 74 Burlington St, East Brisbane, sold recently for $847,000.Ms Conisbee said Brisbane was also faring better than most other capital city rental markets. “One reason is the market had a bit of an undersupply of rental housing heading into COVID,” she said. “Vacancy rates were low by March, so (Brisbane) went into lockdowns in a fairly strong state. “We did see a big uptick in properties available to rent immediately following the announcements of COVID lockdowns, but since then we are now seeing a reduction in rental properties available. It is looking far more positive than it was.” Ms Conisbee said that while investors were still cautious, the good thing for the rental market was that many renters were returning to work. Realestate.com.au chief economist Nerida Conisbee. Image: AAP/Monique Harmer.A new study has also identified five suburbs with the right metrics for future value growth — highlighting Bridgeman Downs, Karalee, Newport, Thornlands and Arundel as the best places to invest in property right now.Aspire Property Advisor Network conducted a suburb-level study of Australian Bureau of Statistics data around population density, resident demographics, household composition, owner occupier-to-renter ratio and property investment type to identify the suburbs.Aspire managing director Richard Crabb said these were areas where rents were expected to hold firm and the potential for value gains looked good.“It’s too simplistic to claim Australia will see ‘ballooning vacancy rates and plummetingweekly rents’ due to a COVID downturn when we have such diverse property markets,” MrCrabb said.“Not all markets are the same. Sophisticated investors know that some locations will do well, even during the crisis.”Mr Crabb said the southeast Queensland region already had the best fundamentals for great investment performance in the nation.“Many of these are lifestyle suburbs where residents have discovered they can work fromhome and enjoy all the benefits their suburb has to offer without the commuter hassle,” Mr Crabb said. THE SUBURBS WITH THE BIGGEST RISE IN MEDIAN RENTS IN MAY Houses Units Suburb Median rental price Monthly rise Suburb Median rental price Monthly rise Newport in the Redcliffe Peninsula’s is renowned for its lifestyle appeal, but not so much its investment potential.“This is a canal-front address with all the water-based lifestyle appeal you’d expect,” Mr Crabb said.“In addition, there’s comprehensive facilities within proximity, and a short drive to thehighway will have you heading north to the Sunshine Coast or south to Brisbane in no time.Mr Crabb said the medical industry was a strong employer and household incomes were, on average, $588 per week higher than the state’s average.last_img read more