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Since the 1800s, scientists have marveled at how spiders can take flight using their webbing. Charles Darwin remarked on the behavior when tiny spiders landed on the HMS Beagle, trailing lines of silk. He thought the arachnids might be using heat-generated updrafts to take to the sky, but new research shows a totally different cause may be at play.
Erica Morley and Daniel Robert from the University of Bristol in England were interested in exploring a second explanation for the spiders’ ability. They thought spiders might sense and use electrostatic fields in the air.
“There have been several studies looking at how air movement and wind can get spiders airborne, but the electrostatic hypothesis was never tested,” Morley told VOA.
Some observers suggested electrostatic fields might be the reason the multiple draglines some spiders use to float don’t get tangled with each other. Biologist Kimberley Sheldon from the University of Tennessee at Knoxville, who was not involved in the new research, pointed out that “though these spiders will have five or six draglines, those strands of silk do not get entangled. So we’ve known for a while that electrostatics probably [are] at least interacting with the spider, with the silk lines themselves, to keep them from getting tangled.”
Morley and Robert created a box with a grounded metal plate on the bottom and a plate on the top that they could pass an electrical current through. The scientists placed spiders in the box and turned on the voltage, watching as the creatures reacted to the electric field.
Reaction to current
When the electric field was on, the spiders lifted their abdomens into the air and started tiptoeing by raising up on the very ends of their legs. Morley told VOA that spiders only tiptoe right before they release silk draglines to fly away, in a process called ballooning.
And when the spiders did balloon and rise into the air, turning off the electric current caused them to drop.
Sheldon compared it to taking a balloon and rubbing it against your clothing. “If you hold the balloon [near your head], your hair stands on end. That’s kind of what’s happening with the spider silk.”
Clearly the spiders were able to sense the local electrostatic field and respond appropriately by releasing silk, but Morley and Robert wanted to know how.
“As a sensory biologist, I was keen to understand what sensory system they might use to detect electric fields,” said Morley. “We know that they have very sensitive hairs that are displaced by air movements or even sound. So I thought that it’s possible that they might be using these same hairs to detect electric fields.”
This was exactly what she observed. The small hairs along the spiders’ legs react not only to physical experiences like a breeze but also to the electric field. In nature, it makes sense for spiders to sense both the electrostatic field around them as well as wind conditions. Spiders probably use both when taking off and navigating the skies.
Mathematician Longhua Zhao from Case Western Reserve University in Cleveland has made computer models of how spiders balloon. She told VOA, “I think that both the electrical field and the fluid mechanics [of air flow] are important. They definitely play very important roles. However, we don’t know at this point which is the dominant factor.”
Lead researcher Morley pointed out that spiders aren’t the only invertebrates to balloon. “Caterpillars and spider mites, which are arachnids but not spiders, balloon as well.” Morley hopes to see others follow up her research to see if these other animals respond in a way similar to the spiders. (VOA)
NEW DELHI - India Navy sending four ships for exercises and port visits with the Philippines, Vietnam, Singapore, Indonesia and Australia to strengthen cooperation in the Indo-Pacific region, its navy said Wednesday, as China's maritime power grows in the area.
The Indian ships will spend more than two months in the region, the navy said in a statement.
Commander Vivek Madhwal, the Indian navy spokesman, said four ships will take part.
The ships will also participate in a multilateral exercise, MALABAR-21, along with the Japanese, Australian and U.S. navies, the statement said.
It said the exercises will enhance coordination with friendly countries, based on common maritime interests and a commitment to freedom of navigation.
"Besides regular port calls, the task group will operate in conjunction with friendly navies to build military relations and develop interoperability in the conduct of maritime operations," the statement said.
The U.S., India, Japan and Australia are part of the Quad regional alliance created in response to China's growing economic and military strength. Washington has long viewed New Delhi as a key partner in efforts to blunt increasing Chinese assertiveness in the Indo-Pacific region.
India is also in a continuing standoff with China over their disputed border in the eastern Ladakh region. The countries have stationed tens of thousands of soldiers backed by artillery, tanks and fighter jets along their de facto border, called the Line of Actual Control.
Last year, 20 Indian troops died in a clash with Chinese soldiers involving clubs, stones and fists in a portion of the disputed border. China said it lost four soldiers.(VOA/HP)
The UK government on Thursday announced that it will move India from the red to the amber list on Sunday, in the country's latest update to the 'Red-Amber-Green' traffic light ratings for arrivals into England amid the Covid-19 pandemic.
This means the visit visas for the UK from India are open, in addition to other long-term visas that have remained open. But travellers from India arriving in England can complete a 10-day quarantine at home or in the place they are staying (not mandatorily quarantine in a managed hotel).
The UK government also announced that arrivals from France to England will no longer need to quarantine if they are fully vaccinated. The step aligns France with the rest of the amber list now that the proportion of beta variant cases has fallen, where those who are fully vaccinated with a vaccine authorised and administered in the UK, the US or Europe do not need to quarantine when arriving in England.
This move also simplifies the system to three categories, as well as the green watch list to give travellers notice where green status is at risk.
To continue cautiously reopening international travel, Austria, Germany, Slovenia, Slovakia, Latvia, Romania and Norway will be added to the government's green list, having demonstrated they posed a low risk to UK public health.
Besides India, Bahrain, Qatar and the UAE will also be moved from the red to the amber list, as the situation in these countries has improved.
The data for all countries will be kept under review and the government will not hesitate to take action where a country's epidemiological picture changes, a statement by the UK government said.
Following an assessment of the latest data, Georgia, La Reunion, Mayotte and Mexico will be added to the red list as they present a high public health risk to the UK from known variants of concern, known high-risk variants under investigation or as a result of very high in-country or territory prevalence of Covid-19.
Arrivals from Spain and all its islands are advised to use a PCR test as their pre-departure test wherever possible, as a precaution against the increased prevalence of the virus and variants in the country.
Transport Secretary Grant Shapps said: "We are committed to opening up international travel safely, taking advantage of the gains we've made through our successful vaccination programme, helping connect families, friends and businesses around the world.
"While we must continue to be cautious, today's changes reopen a range of different holiday destinations across the globe, which is good news for both the sector and travelling public."
Since February, anyone who arrives in the UK from a red list country has been required by law to book a stay in a managed quarantine facility for 10 days.
In order to ensure taxpayers are not subsidising the costs of staying in these facilities, which have gone up, the cost will increase from August 12. Alternative payment arrangements remain available to those who genuinely cannot afford to pay and rates remain the same for children up to 12.(IANS/HP)
A Hindu temple in Pakistan's Punjab province was reportedly vandalized by hundreds of people after a nine-year-old Hindu boy, who allegedly urinated at a local seminary, received bail, a media report said on Thursday.
According to the Dawn news report, the incident took place on Wednesday in Bhong town, about 60 km from Rahim Yar Khan city.
Besides the vandalization, the mob also blocked the Sukkur-Multan Motorway (M-5), the report added.
Citing sources, Dawn news said that a case was registered against the minor on July 24 based on a complaint filed by a cleric, Hafiz Muhammad Ibrahim, of the Darul Uloom Arabia Taleemul Quran.
The sources said that "some Hindu elders did tender an apology to the seminary administration saying the accused was a minor and mentally challenged".
But, when a lower court granted him bail a few days ago, some people incited the public in the town on Wednesday and got all shops there closed in protest, the report quoted the sources as further saying.
A video clip showing people wielding clubs and rods storming the temple and smashing its glass doors, windows, lights, and damaging the ceiling fans went viral on social media.
In response, one Twitter user said: "Ganesh Temple, village Bhong in Rahim Yar Khan, Punjab has been ravaged. Another day, another attack on Hindus in Pakistan."
Another said: "Yesterday, the mob ran amok at Temple over minor boy issue who allegedly urinated, the boy said to be mentally handicapped. Hindu community made an apology for the boy — a case registered against the nine-year-old boy. Those vandalized temples, no FIR registered against them."
District police spokesman Ahmed Nawaz Cheema said Rangers had been deployed in the troubled area and the situation was under control.
A small town close to the River Indus and Sindh-Punjab border, Bhong houses a number of gold traders who originally hail from Ghotki and Dehrki (Sindh), according to the Dawn news report.
A ruling PTI member representing the minority said he had been in touch with the local Hindu community and influential Rais family of Bhong since the issue surfaced.