Launch limit for pterosaur flight

first_imgBERLIN—The ancient flying reptiles called pterosaurs include the largest flying animals ever discovered, with estimated wingspans as wide as 11 meters, the width of a doubles tennis court. Exactly how such gargantuan creatures could have taken off, stayed aloft, and landed safely has long puzzled biomechanics experts. New calculations presented here last week at the Society of Vertebrate Paleontology’s annual meeting suggest that flying and landing weren’t problems even for the biggest specimens, but takeoff probably limited how large the animals could grow.Pterosaurs existed from the late Triassic until the end of the Cretaceous period—about 200 million to 66 million years ago. Although they lived at the same time, pterosaurs are not dinosaurs; they form a distinct branch of the evolutionary tree. The most famous member of the group is the first named species, Pterodactylus antiquus, commonly known as a pterodactyl. They were some of the smaller pterosaurs, with an estimated adult wingspan of about a meter, about the size a peregrine falcon. The largest known pterosaurs, Hatzegopteryx, unearthed in Romania, and Quetzalcoatlus, found in Texas, are thought to have had wingspans of 10 or 11 meters—more than three times the wingspans of today’s largest birds.Some researchers have argued that those giants were simply too large to fly. But given their large wings—a skin-and-muscle membrane that extended between an extended fourth finger and the animals’ hind legs—most researchers think they did spend time in the air. Many previous models and estimates were based on scaling up the physiology of birds, but pterosaurs had such different body plans that those models are potentially misleading, says Colin Palmer of the University of Bristol in the United Kingdom. He and Michael Habib of the University of Southern California in Los Angeles attempted to devise a more accurate model of the forces on the animals as they launched, flew, and landed. They used computed tomography scans of pterosaur fossils and wind tunnel tests of model pterosaur wings to develop a computer model of a pterosaur with a 6-meter wingspan. They then scaled up their model to have 9-meter and 12-meter wingspans and calculated the forces on the animals’ bones, wings, and muscles as they took off, flew, and landed.Sign up for our daily newsletterGet more great content like this delivered right to you!Country *AfghanistanAland IslandsAlbaniaAlgeriaAndorraAngolaAnguillaAntarcticaAntigua and BarbudaArgentinaArmeniaArubaAustraliaAustriaAzerbaijanBahamasBahrainBangladeshBarbadosBelarusBelgiumBelizeBeninBermudaBhutanBolivia, Plurinational State ofBonaire, Sint Eustatius and SabaBosnia and HerzegovinaBotswanaBouvet IslandBrazilBritish Indian Ocean TerritoryBrunei DarussalamBulgariaBurkina FasoBurundiCambodiaCameroonCanadaCape VerdeCayman IslandsCentral African RepublicChadChileChinaChristmas IslandCocos (Keeling) IslandsColombiaComorosCongoCongo, The Democratic Republic of theCook IslandsCosta RicaCote D’IvoireCroatiaCubaCuraçaoCyprusCzech RepublicDenmarkDjiboutiDominicaDominican RepublicEcuadorEgyptEl SalvadorEquatorial GuineaEritreaEstoniaEthiopiaFalkland Islands (Malvinas)Faroe IslandsFijiFinlandFranceFrench GuianaFrench PolynesiaFrench Southern TerritoriesGabonGambiaGeorgiaGermanyGhanaGibraltarGreeceGreenlandGrenadaGuadeloupeGuatemalaGuernseyGuineaGuinea-BissauGuyanaHaitiHeard Island and Mcdonald IslandsHoly See (Vatican City State)HondurasHong KongHungaryIcelandIndiaIndonesiaIran, Islamic Republic ofIraqIrelandIsle of ManIsraelItalyJamaicaJapanJerseyJordanKazakhstanKenyaKiribatiKorea, Democratic People’s Republic ofKorea, Republic ofKuwaitKyrgyzstanLao People’s Democratic RepublicLatviaLebanonLesothoLiberiaLibyan Arab JamahiriyaLiechtensteinLithuaniaLuxembourgMacaoMacedonia, The Former Yugoslav Republic ofMadagascarMalawiMalaysiaMaldivesMaliMaltaMartiniqueMauritaniaMauritiusMayotteMexicoMoldova, Republic ofMonacoMongoliaMontenegroMontserratMoroccoMozambiqueMyanmarNamibiaNauruNepalNetherlandsNew CaledoniaNew ZealandNicaraguaNigerNigeriaNiueNorfolk IslandNorwayOmanPakistanPalestinianPanamaPapua New GuineaParaguayPeruPhilippinesPitcairnPolandPortugalQatarReunionRomaniaRussian FederationRWANDASaint Barthélemy Saint Helena, Ascension and Tristan da CunhaSaint Kitts and NevisSaint LuciaSaint Martin (French part)Saint Pierre and MiquelonSaint Vincent and the GrenadinesSamoaSan MarinoSao Tome and PrincipeSaudi ArabiaSenegalSerbiaSeychellesSierra LeoneSingaporeSint Maarten (Dutch part)SlovakiaSloveniaSolomon IslandsSomaliaSouth AfricaSouth Georgia and the South Sandwich IslandsSouth SudanSpainSri LankaSudanSurinameSvalbard and Jan MayenSwazilandSwedenSwitzerlandSyrian Arab RepublicTaiwanTajikistanTanzania, United Republic ofThailandTimor-LesteTogoTokelauTongaTrinidad and TobagoTunisiaTurkeyTurkmenistanTurks and Caicos IslandsTuvaluUgandaUkraineUnited Arab EmiratesUnited KingdomUnited StatesUruguayUzbekistanVanuatuVenezuela, Bolivarian Republic ofVietnamVirgin Islands, BritishWallis and FutunaWestern SaharaYemenZambiaZimbabweI also wish to receive emails from AAAS/Science and Science advertisers, including information on products, services and special offers which may include but are not limited to news, careers information & upcoming events.Required fields are included by an asterisk(*)Staying airborne was no problem for their model pterosaurs, Palmer told the meeting. Even animals with wingspans of 15 meters would have had enough muscle power to counteract the drag that exists when the animal is in the air. Landing is a more complicated process, he says, and those modeling experiments were less definitive. The calculations didn’t place a clear limit on the ability of bone to absorb the stress of landing, but even up to 12 meters, Palmer says, their model animals could land safely.Taking off was the biggest challenge for the model pterosaurs. The animals probably launched using all four limbs (scientists think they walked on all fours) and so had more muscle power available than today’s birds do. Model animals with wingspans of 9 or 10 meters had no problem taking off. But according to the model, animals with wingspans greater than 11 meters had trouble jumping high enough to start flapping their wings fully before they fell back to the ground. Thus, the larger pterosaurs couldn’t launch very effectively. In theory, animals even bigger than that could get airborne under ideal conditions, with a hard surface under them and no headwind. “But without ideal conditions, you get eaten,” Palmer says. Habib agrees. An animal with a 12-meter wingspan “could leap in a computer,” he says, “but the real world had Tyrannosaurus in it.”All such computer models have limitations, says Alexander Kellner of the Brazilian National Museum at the Federal University of Rio de Janeiro. But the new calculations do help researchers better understand the physiological limits of the flying giants. “They were very different from anything living today,” he says, so basing models on fossil data is important. Additional fossil scans could help refine the models even further, he says.last_img read more

Surgeons can now suture blood vessels in half the time, thanks to IIT student invention

first_imgA tiny eversion clamp, not larger than a thumbnail, is all set to revolutionise the way doctors operate on blood vessels apart from reducing cost and complications of surgeries.The clamp called Nstomoz has been developed by Anand Parikh, an M.Tech student of the Indian Institute of Technology, Madras.One of the most complicated jobs of a junior surgeon involves reconnecting blood vessels, a process known as vascular anastomosis. Sheer practicing for years helps specialists including in vascular, cardiovascular, plastic and transplant surgeons master it.One wrong stitch can lead to various serious complications such as thickening of the inner-most layer of the blood vessel, tunica intima.The process is so delicate that sometimes trauma patients’ limbs are severed in lack of specialists to suture blood vessels.”It’s tough for beginners. Some are so disappointed with their skill levels that they stop doing it altogether,” said Dr Narayanamurthy who has been teaching microvascular surgeries for 15 years, according to TOI .Around five years ago, the surgeon briefed engineers in the department of engineering design at IIT-Madras about the need for devices that could help people like him.Two years ago, Parikh decided to develop a clamp for micro vascular surgeries as a part of his engineering project. “I spent several days listening to doctors and watched them perform surgeries. I realised that the procedure was complex and long because the blood vessels collapse when they suture it,” he said.Clamps are used to stop blood flow into vessels that need to be sutured. Conventionally, once a surgeon clips the vessels with these clamps, it shrinks, making it tough for them to perform the end-to-end stitches. Nstomoz has been developed to ensure that the vessel does not collapse.advertisementThis innovation even bagged the Gandhian Young Technological Innovation (GYTI) Award for the product earlier this month.While testing in the lab, the clamp helped surgeons’ suture blood vessels at twice the speed of the conventional method. The team is now looking at various options for manufacturing these clamps for the market.”We have filed for two patents. The product will be launched from the incubation ecosystem of IIT Madras,” said Venkatesh Balasubramanian, department of engineering design professor.Check: Limit on weight of school bags to apply on all schools: Maharashtra govtClick here to get more education news.Get latest updates on exam notifications and scholarships across India and abroad here.last_img read more