爱上海同城对对碰aish

first_imgIn addition to the blood and bone, thearrow heads also held traces of glue in theform of a plant-based resin that thescientists think was used to fasten themonto wooden or reed shafts. Marlize Lombard, a researcher andlecturer in Anthropology at the Universityof Johannesburg, at the Sibundu Cave sitein the north of KwaZulu-Natal province.(Images: University of Johannesburg)MEDIA CONTACTS• Lyn WadleyHonorary Professor, School of Geography,Archaeology and Environmental StudiesUniversity of the Witwatersrand+27 11 717 [email protected] African archaeologists have found what is believed to be the earliest evidence of human-made stone-tipped arrows, 64 000-year-old stone tools – still with traces of blood and bone – that push the development of bow-and-arrow technology back 20 000 years and throw light on humanity’s cognitive development.The finds, unearthed from layers of very old sediment in Sibundu Cave in the north of KwaZulu-Natal province, were made by Marlize Lombard of the University of Johannesburg and a team of researchers and scientists under the leadership of Lyn Wadley of the University of the Witwatersrand (Wits), also in Johannesburg.A bone point that could have been an arrow tip was also excavated from the site in 2008 by Lucinda Backwell and colleagues from Wits.The shape of the geometric stone pieces indicated where they had been impacted and damaged, and how they were hafted, Lombard said. “This showed that the pieces were very likely to have been the tips of projectiles – rather than sharp points on the end of hand-held spears.”In addition to the blood and bone, the arrow heads also held traces of glue in the form of a plant-based resin that the scientists think was used to fasten them onto wooden or reed shafts.“The presence of glue implies that people were able to produce composite tools – tools where different elements produced from different materials are glued together to make a single artefact,” said Lombard.The sophistication of the arrows sheds light on the development of human intelligence, scientists believe. According to Larry Barham from the University of Liverpool, “This is an indicator of a cognitively demanding behaviour.”The discovery, together with other evidence, pushes back the development of bow-and-arrow technology by at least 20 000 years. The team’s findings were published in the latest issue journal Antiquity.Ancient engineering Scientists’ interest in early bows and arrows stems from the light the weapons shine on the technological and cognitive abilities of early Homo sapiens.“Hunting with a bow and arrow requires intricate multi-staged planning, material collection and tool preparation and implies a range of innovative social and communication skills,” the researchers wrote in their article.Lombard said that her ultimate aim was to explore the big question: “When did we start to think in the same way that we do now?”“Together with additional evidence from Sibudu produced by Prof Wadley and her team, and other South African sites such as Blombos, under the direction of Prof Chris Henshilwood, we are becoming more and more confident that 60 000 to 70 000 years ago, in Southern Africa, people were behaving, on a cognitive level, very similarly to us.”Chris Stringer from the Natural History Museum in London said the work added to the view that modern humans in Africa 60 000 years ago had begun to hunt in a “new way”.Neanderthals and early humans, he explained, were likely to have been “ambush predators”, who needed to get close to their prey in order to dispatch them.“This work further extends the advanced behaviours inferred for early modern people in Africa,” Stringer said. “But the long gaps in the subsequent record of bows and arrows may mean that regular use of these weapons did not come until much later.“Indeed, the concept of bows and arrows may even have had to be reinvented many millennia later.”last_img read more

first_imgTags:#Borophene#Graphene#Internet of Things#IoT#Rice University#wearables Small Business Cybersecurity Threats and How to… Graphene has been touted as a possible next generation material for wearables, smartphones, and other electronic devices, but scientists at Rice University suspect borophene, an atom-thick substance, could provide even better results.One of the main differences between graphene and borophene is the undulating structure it takes when moved from its typical state, metallic, to silver substrate. Its structure remains intact during this process, meaning it can retain its flexibility.See Also: Does Zap&Go have this energy storage issue solved?“Borophene is metallic in its typical state, with strong electron-phonon coupling to support possible superconductivity, and a rich band structure that contains Dirac cones, as in graphene,” said Rice physicist Boris Yakobson.Borophene superconductivity is criticalSuperconductive material is highly valuable in the wearables industry, where signals and circuitry must flow without any issues. The scientists believe borophene (2D boron) would be good for wearables, but may perform even better with flexible devices.The benefits of graphene are seen in its ability to not just to conduct energy quickly, but to provide an energy storage solution that can avoid the fire or explosion hazards of traditional lithium ion batteries. Borophene appears to add a new layer of flexibility to those attributes.“This wavy conformation so far seems unique due to the exceptional structural flexibility and particular interactions of borophene with silver, and may be initially triggered by a slight compression in the layer when a bit too many boron atoms get onto the surface,” said postdoctoral researcher Zhuhua Zhang.The likelihood of borophene entering the wearables market in the next few years is small, considering the limitations of the material at the current time, but it does show the potential future for device manufacturers should metal and plastic ever fail to impress. David Curry Why IoT Apps are Eating Device Interfacescenter_img Internet of Things Makes it Easier to Steal You… Related Posts Follow the Pucklast_img read more

first_imgBeijing: Visiting Philippine President Rodrigo Duterte held talks Thursday with his Chinese counterpart, Xi Jinping, in which the Southeast Asian leader was expected to discuss a ruling on the disputed South China Sea. The 2016 Hague arbitration ruling mostly invalidated China’s claim to virtually the entire South China Sea and found that it violated the UN Convention on the Law of the Sea. The row over the waters a major global shipping route thought to be rich in oil and gas reserves has for years marred China’s relationship with the Philippines and other neighboring countries with rival territorial claims. Beijing has transformed a string of disputed reefs into missile-protected island bases. Also Read – Saudi Crown Prince ‘snubbed’ Pak PM, recalled jet from USDuterte, however, has largely avoided the subject in favor of seeking warmer ties with Beijing. Philippine nationalists and left-wing groups have criticized the president for not demanding Chinese compliance with the arbitration ruling, which came the same year Duterte took office. Philippine Ambassador to China Jose Santiago “Chito” Santa Romana told reporters Thursday that Duterte has mentioned the ruling to Xi several times, but not in a direct discussion as he planned to do this meeting. Also Read – Record number of 35 candidates in fray for SL Presidential pollsDuterte “has exerted a lot of diplomatic capital to build a reservoir of goodwill and friendship with President Xi,” Santa Romana said. “So he has decided that it’s time to include in the diplomatic agenda and in the discussions sensitive issues that may have caused misunderstanding if it were brought up in the past.” Santa Romana added that Duterte is in Beijing “to build bridges, not to burn bridges with China.” It’s unlikely that Duterte’s move will have any effect on China, said Jay Batongbacal, a maritime affairs scholar at the University of the Philippines. “China’s position will not change just because Duterte changes tune,” Batongbacal said. “At best, Duterte might be seen as using the arbitration discussion as a move to leverage other concessions. At worst, it may be just for show.” At the start of Thursday’s meeting, Xi said he was willing to work with Duterte to “grasp the current situation” from a long-term, strategic perspective. “This will not only benefit our two countries and our peoples, but also will provide positive energy to the region,” Xi said. Neither leader mentioned the South China Sea in their introductory remarks in the presence of reporters.last_img read more