Knowledge Update

Beijing, March 17 (IANS) Researchers from China, New Zealand and the US have found four intact mushroom fossils, sources said on Friday.

The four, well preserved in Burmese amber (fossilised sap of extinct trees) for at least 99 million years, are the earliest complete mushroom fossils ever found, according to the sources with the Chinese Academy of Sciences.

The findings represent four species of mushroom. A stalk and a complete cap containing distinct gills are visible in most of the mushrooms, which are two to three mm long, Xinhua news agency reported.

The research team led by professor Huang Diying from Nanjing Institute of Geology and Paleontology, reported the finding after researching more than 20,000 pieces of Burmese amber collected over 10 years.

The discovery highlights the palaeo-diversity of mushrooms, pushing back the presence of agaric mushrooms by at least 25 million years.

Mushrooms are common and morphologically diverse fungi. Their bodies are soft and ephemeral and therefore extremely rare in fossils. 

Until the recent discovery, only five species of mushrooms were known exclusively from amber.

​New York, March 17 (IANS) More than 50 per cent of millennials in the US prefer checking Snapchat first over other social media platforms such as Facebook, Instagram, and LinkedIn, the results of a new survey suggest.

The survey involving nearly 10,000 college students found that 58 per cent of them check Snapchat over Facebook, Instagram, and LinkedIn combined. 

Instagram accounted for 27 per cent, Facebook for 13 per cent, and LinkedIn for two per cent, or a total of 42 per cent, showed the new data gathered by LendEDU, an online marketplace for student loans and student loan refinancing.

The findings suggest that Snap Inc., parent company of messaging app Snapchat, may not only survive the volatile Wall Street environment, but prosper.

Snap Inc has been the word on Wall Street since it went public on March 2.

Snap rode its immense popularity to produce eye-popping numbers during its initial offering, with a first day closing price at $24.53. 

In the days following the IPO, shares of Snap traded lower as exuberance and volume settled. 

But the messaging app's popularity among millenials (born between 1980 and and early 2000s)can help the company prosper in the stock market, according to the new results.

"Overall, Snap's access and importance to millennials will be the driving force behind their success in the stock market," LendEDU said in a report on Thursday.

For the study, LendEDU has gathered this data under license from polling company WhatsGoodly.

According to Snap, the majority of Snapchat users are aged 18-to-34 years old. On an average, these users visit the app 18 times a day for a combined 25 to 30 minutes. 

Additionally, users younger than 25 visit the application more than 20 times a day for more than 30 minutes.

New York, March 16 (IANS) Scientists have developed a new pill that can act as non-invasive alternative to colonoscopies -- an effective way to screen for colon cancer -- and help identify growths called polyps.

Colorectal cancer is the third-leading cause of cancer deaths in women and second leading cause in men. Early detection and screening are essential to reduce the rates of colorectal cancer.

The pill -- PillCam Colon 2 -- contains two miniature cameras on either end. After being ingested by the patient, the capsule travels through the digestive tract, captures images and wirelessly transmits them to a recorder the patient wears on a belt.

Like a colonoscopy, the system can help identify growths called polyps, said researchers from Loyola University in Chicago, US.

During a standard colonoscopy, a flexible tube (colonoscope) is inserted into the rectum and guided by a physician through the colon. A camera at the end of the colonoscope allows for visualisation of polyps.

However, some patients cannot tolerate the procedure, or may be at higher risk for sedation, the researchers said.

With the new system, the patient swallows the capsule with water. After the non-reusable capsule is excreted, it's flushed down the toilet. The patient returns the recorder to the physician's office. If a polyp is found, the patient arranges to undergo a colonoscopy to remove the growth.

"Early detection has been proven to save lives, and the video capsule system offers a convenient screening test for people who are unable to have a complete colonoscopy," Mukund Venu from Loyola University, said in a statement.

The US Food and Drug Administration approved the capsule system for patients whose anatomy of the colon makes it difficult to guide a colonoscope through the entire colon and for patients who have elevated risk of complications due to age or other reasons.

New York, March 16 (IANS) A common genetic variant that accelerates normal brain ageing in older people by up to 12 years has been identified by US researchers.

The findings could point towards a novel biomarker for the evaluation of anti-ageing interventions and highlight potential new targets for the prevention or treatment of age-associated brain disorders such as Alzheimer's disease, the researchers said.

"If you look at a group of elderly, some will look older than their peers and some will look younger. The same differences in ageing can be seen in the frontal cortex, the brain region responsible for higher mental processes," said Asa Abeliovich, Professor at Columbia University Medical Centre (CUMC) in the US.

The results, published in the journal Cell Systems, showed that many of these differences are tied to variants of a gene called TMEM106B. About one-third of people have two copies of TMEM106B and another third have one copy.

People who have two 'bad' copies of this gene have a frontal cortex that, by various biological measures, tends to appear 12 years older than those who have two normal copies.

"TMEM106B begins to exert its effect once people reach age 65. Until then, everybody's in the same boat, and then there's some yet-to-be-defined stress that kicks in. If you have two good copies of the gene, you respond well to that stress. If you have two bad copies, your brain ages quickly," Abeliovich explained.

"It's in healthy tissue that you start to get disease. It appears that if you have these genetic variants, brain ageing accelerates and that increases vulnerability to brain disease. And vice versa: if you have brain disease, the disease accelerates brain ageing," he noted. 

New York, March 15 (IANS) Scientists have developed a high-resolution retinal prosthesis using nanowires and wireless electronics that may aid neurons in the retina to respond to light.

The technology could help tens of millions of people worldwide suffering from neurodegenerative diseases that affect eyesight, including macular degeneration, retinitis pigmentosa and loss of vision due to diabetes.

In the study, detailed in the Journal of Neural Engineering, the researchers demonstrated this response to light in a rat retina interfacing with a prototype of the device in vitro.

"We want to create a new class of devices with drastically improved capabilities to help people with impaired vision," said Gabriel A. Silva, Professor at the University of California San Diego in the US.

The new prosthesis relies on two ground-breaking technologies. One consists of arrays of silicon nanowires that simultaneously sense light and electrically stimulate the retina accordingly.

The nanowires give the prosthesis higher resolution than anything achieved by other devices -- closer to the dense spacing of photoreceptors in the human retina. 

The other is a wireless device that can transmit power and data to the nanowires over the same wireless link at record speed and energy efficiency.

Further, the new system does not require a vision sensor outside of the eye to capture a visual scene and then transform it into alternating signals to sequentially stimulate retinal neurons.

Instead, the silicon nanowires mimic the retina's light-sensing cones and rods to directly stimulate retinal cells.

Nanowires are bundled into a grid of electrodes, directly activated by light and powered by a single wireless electrical signal. 

The power provided to the nanowires from the single wireless electrical signal gives the light-activated electrodes their high sensitivity while also controlling the timing of stimulation.

Seoul, March 15 (IANS) Challenging a commonly held theory that changes in the Earth's orbit triggered Sahara desertification, a new study suggests that humans may have played an active role in the transition of a lush green landscape into the world's largest hot desert thousands of years ago.

The desertification of the Sahara has long been a target for scientists trying to understand climate and ecological tipping points. 

Most studies done to date point to changes in the Earth's orbit or natural changes in vegetation as the major driving forces.

In a new paper published in the journal Frontiers in Earth Science, David Wright from Seoul National University in South Korea challenges the conclusions of these studies.

"In East Asia there are long established theories of how Neolithic populations changed the landscape so profoundly that monsoons stopped penetrating so far inland," said Wright. 

Evidence of human-driven ecological and climatic change has been documented in Europe, North America and New Zealand, said Wright who believed that similar scenarios could also apply to the Sahara.

To test his hypothesis, Wright reviewed archaeological evidence documenting the first appearances of pastoralism across the Saharan region, and compared this with records showing the spread of scrub vegetation, an indicator of an ecological shift towards desert-like conditions. 

The findings confirmed his thoughts.

Beginning approximately 8,000 years ago in the regions surrounding the Nile River, pastoral communities began to appear and spread westward, increasing at the same time the spread of scrub vegetation, the study said.

Growing agricultural addiction had a severe effect on the region's ecology. As more vegetation was removed by the introduction of livestock, it increased the albedo (the amount of sunlight that reflects off the earth's surface) of the land, which in turn influenced atmospheric conditions sufficiently to reduce monsoon rainfall. 

The weakening monsoons caused further desertification and vegetation loss, promoting a feedback loop which eventually spread over the entirety of the modern Sahara, the study said.

London, March 15 (IANS) Stimulating the brain with electricity may synchronise brain waves and help improve short-term working memory that could improve treatments for people with traumatic brain injury, stroke or epilepsy, a study has found.

According to researchers, applying a weak electrical current through the scalp can align different parts of the brain, synchronising brain waves and enabling people to perform better on tasks involving working memory.

"What we observed is that people performed better when the two waves had the same rhythm and at the same time," said lead author Ines Ribeiro Violante, a neuroscientist at the Imperial College London.

"The hope is that it could eventually be used for patients with brain injury, or even those who have suffered a stroke or who have epilepsy," Violante added. 

For the study, published in the journal eLife, the team used a technique called transcranial alternating current stimulation (TACS) to manipulate the brain's regular rhythm in 10 volunteers.

Using TCAS, the researchers targeted two brain regions -- the middle frontal gyrus and the inferior parietal lobule -- known to be involved in working memory.

The findings revealed that when the brain regions were stimulated in sync, reaction times on the memory tasks improved.

Functional MRI images of the brain showed changes in activity occurring during stimulation, with the electrical current potentially modulating the flow of information.

"The results show that when the stimulation was in sync, there was an increase in activity in those regions involved in the task. When it was out of sync, the opposite effect was seen.

"The hope is that it could eventually be used for patients with brain injury, or even those who have suffered a stroke or who have epilepsy," Violante added.

​Buenos Aires, March 14 (IANS) The worlds first fluorescent frog has been discovered in the Amazon basin in Argentina, a media report said on Tuesday.

Scientists at the Bernardino Rivadavia Natural Sciences Museum in Buenos Aires made the discovery by accident while studying the pigment of polka-dot tree frogs, a species common to the rainforest, the Guardian said in the report.

In normal light the frog appears to have a dull, mottled brown-green skin with red dots, but under UV light it glows a bright fluorescent green.

Fluorescence -- the ability to absorb light at short wavelengths and re-emit it at longer wavelengths -- is uncommon in creatures that live on land.

The translucent frog was found to use a combination of lymph and glandular emissions to fluoresce.

The researchers, who published their discovery on Monday in Proceedings of the National Academy of Sciences, found that the trait enhanced the brightness of the frog by 19-29 per cent depending on the level of ambient light in its surroundings, the daily said.

The compound causing the blue-green glow of the polka-dot tree frog was not previously thought to exist in vertebrates and its discovery has excited researchers.

"This is very different from fluorophores found in other vertebrates, which are usually proteins or polyenic chains," Maria Gabriella Lagoria, a photochemist at the University of Buenos Aires and study co-author, told Chemistry World.

The discovery opens up the possibility that other amphibians may be able to fluoresce, particularly those with translucent skin similar to that of the tree frog.

Speaking to the journal Nature, which first published news of the fluorescent frog, co-author Julian Faivovich expressed his hope that the discovery would inspire interest in the phenomenon, saying he hoped scientists would "start carrying a UV flashlight to the field".

​London, March 14 (IANS) Although parenthood may have its share of woes, it could also hold the key to long life, particularly in older age, when health and capacity may start to decline, finds a new study.

The findings suggested that the risks of death were lower among those who had had at least one child than they were among those who were childless -- and more so among men than among women -- and were not affected by the sex of the child(ren).

"We started first at the age of 60 and we looked all the way up to the age of 100," Karin Modig from Karolinska Institute Sweden was quoted as saying by guardian.com.

At age 60, the difference in the one-year risk of death was 0.06 per cent among men and 0.16 per cent among women.

The one-year risk of death for an 80-year-old man with a child was 7.4 per cent, for example, compared with 8.3 per cent for a childless man of the same age.

The gap in absolute death risks between the two groups rose with increasing age, and was somewhat larger for men than it was for women.

By the age of 90, these differences had risen to 1.47 per cent among men and to 1.10 per cent among women.

Further, the difference in death risk was 1.2 per cent among unmarried men and 0.6 per cent among those who were married.

"Our finding that the association grew stronger when parents became older is further in agreement with study suggesting that childless people face support deficits only towards the end of life," the researchers noted, in the paper published online in the Journal of Epidemiology & Community Health.

For the study, the team tracked the lifespan from the age of 60 onwards of all men (704,481) and women (725,290) in Sweden.

Tokyo, March 14 (IANS) Japanese authorities sent a robot to the Fukushima nuclear plant on Tuesday to measure radiation levels inside and evaluate its condition ahead of a future dismantling of a reactor.

The self-propelled, remotely-operated robot is equipped with a video camera, thermometer as well as dosimeter -- to measure radiation -- among other sensors, said the Tokyo Electric Power Company (TEPCO), the maker of the bot, in a statement.

Using the recorded data and footage, experts will try to ascertain the presence of melted fuel that could have leaked from the reactor core and accumulated at the bottom of the containment vessel, something they have been unable to verify so far, Efe news reported.

Determining the exact conditions inside the reactor is a necessary step for drafting a plan on the future recovery of the nuclear fuel; a task that has been made difficult by fatal radiation levels at the heart of the nuclear installations.

TEPCO had introduced two bots into the reactor earlier but while the first one could not make it out of the reactor, the second one became inoperative due to extreme radiation.

Another robot that TEPCO sent was also damaged by radiation, but managed to record footage that supplied important information on conditions inside, said the company.

Reactors No. 1, 2 and 3 had suffered partial meltdowns due to an earthquake and a tsunami that hit Japan in March 2011.

The Fukushima nuclear accident is considered the world's worst since Ukraine's Chernobyl disaster in 1986.