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Mon, 25 Jul 2016
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Butterfly

Butterfly bacteria creates separate, female only species

© University of Exeter
Tiny microbe turns tropical butterfly into male killer.
They are so beautiful, these man-eaters.

In Nairobi, the heart of Kenya, within what scientists call a hybrid zone for butterflies, two subspecies of the African queen have no males. That's because the females are infected with a bacterium known as Spiroplasma ixodeti that kills 100 percent of their male offspring. The eggs don't hatch.

What's worse, at least for the males, is that the female eggs hatch normally, and their doomed brothers are among their first meals. The Daryl Hall and John Oates lyrics say it best: "Oh-oh here she comes. Watch out, boy, she'll chew you up. ... She's a man-eater."

Don't blame the lovely cannibal butterflies, said Richard ffrench-Constant, a professor of molecular natural history at the University of Exeter in England and the author of a study released Tuesday. Blame nature. "The sisters eating their dead brothers is just a byproduct of the males dying in their eggs," he said very matter-of-factly. "Many caterpillars eat their own eggs after hatching, so it's probably just a by-product of that."

Attention

Newly discovered giant megathrust fault has potential to kill millions


More than 140 million people live within a 60 mile area of the potential disaster zone in Bangladesh.
A giant fault in the earth's crust covers by millions of tonnes of sediment in one of the world's most densely populated areas could kill tens of millions of people, scientists have claimed.

Researchers placed hundreds of highly accurate GPS receivers in locations across India, Bangladesh and Myanmar and monitored them over a ten year period.

Now the scientists fear the location is home to a megathrust fault which could unleash a 9.0 magnitude earthquake at any minute.

The scientists, led by Dr Michael Steckler from Columbia University published their findings in the journal Nature.

The experts discovered that millions of tonnes of sediment from the Ganges and Brahmaputra rivers has been dumped into the megathrust fault, where one of the earth's plates is being pushed under another.

Beaker

Natural mosquito repellent? Chickens

© CDC
For the first time, scientists have shown that malaria-transmitting mosquitoes actively avoid feeding on certain animal species such as chickens, using their sense of smell. Odors emitted by species such as chickens could provide protection for humans at risk of mosquito-transmitted diseases, according to a study in the open access Malaria Journal.

Researchers at the Swedish University of Agricultural Sciences and Addis Ababa University, Ethiopia found that Anopheles arabiensis, one of the predominant species transmitting malaria in sub-Saharan Africa, avoids chickens when looking for hosts to feed on. This indicates that, unlike humans, cattle, goats and sheep, chickens are a non-host species for An. arabiensis and that the mosquitoes have developed ways of distinguishing them from host species.

Rickard Ignell, the corresponding author, said:
"We were surprised to find that malaria mosquitoes are repelled by the odors emitted by chickens. This study shows for the first time that malaria mosquitoes actively avoid feeding on certain animal species, and that this behavior is regulated through odor cues."

Comment: Read the study here [link]

Also see Why mosquitos attack some, but leave others alone


Comet 2

Halley's comet orbit being altered by Venus instead of Jupiter

© NASA
Halley’s comet.
If you're waiting for Halley's comet to show up exactly 75 years after its 1986 appearance, you may be disappointed. The ball of ice has an orbit that varies by months or even years.

And new research suggests that Venus is responsible for the comet's variations today, rather than the more massive planet Jupiter.

"Comet Halley has been observed throughout history, all the way back to 240 BC by the Chinese," Tjarda Boekholt, an astrophysicist at Leiden Observatory in the Netherlands, told Discover by email.

Erratic Schedule

With many well-documented appearances, scientists quickly realized that the arrival time of the comet was constantly changing. For instance, although it passed Earth in February in 1986, it won't be back until February 2061. In 45 years, it will instead appear in July.

"It is the variation in the time of sightings that provided the first clue to comet Halley's chaotic orbit," Boekholt said. "The orbit of comet Halley is not static, but it is evolving."

Boekholt led a team that investigated the comet's changing orbit. They found that Venus played an important role in revising the comet's orbit in the past, and will probably continue to do so in the future, despite its small stature. Mighty Jupiter often dominates the influence of gravitational bodies due to its high mass, but Venus currently dominates Halley's is movements.

The research will be published in the journal The Monthly Notices of the Royal Astronomical Society. A preprint is available online.

Mars

NASA allows Mars 'Curiosity' rover to fire laser at will

© NASA
When NASA launched Curiosity Rover, a 1-ton robotic beast that would basically take planetary exploration to the next level, we all knew we were in for a brilliant treat.

The car-sized Curiosity rover is the centerpiece of NASA's US$2.5 billion Mars Science Laboratory mission to Mars. Curiosity was sent to the Red Planet to assess whether it is, or ever will be, capable of supporting microbial life.

Well its official, the Curiosity Rover has just become even cooler — and here's why:

Robot

China to launch first fully-automatic driverless subway train

© AFP 2016/ GREG BAKER
The first fully-automatic subway train entirely developed in China will be put into operation in Beijing in 2017, media reported Friday.

According to the China Radio International (CRI), the trial of the subway train on 35-kilometer-long (22 miles) Yanfang Line linking Hebei's Yanjiao and Fangshan district in Beijin will be launched in December 2016, while the commissioning is expected by the end of 2017.

Once integrated into an automatic metro system, the driverless trains will be able to run between the stations and make stops, open and close doors and return to the terminal station. It is expected that the automatic trains will run well on schedule without any delay.

The fully-automatic trains are designed by the Chinese CRRC Corporation Limited company, a state-owned rolling stock manufacturer.

Better Earth

Wild birds and humans cooperate to find honey in Mozambique

© Claire N. Spottiswoode
Yao honey hunter Orlando Yassene holds a female honeyguide bird.
Over thousands of years, honey hunters in northern Mozambique have forged a relationship with wild birds to find the location of bees' nests.

But not only do humans seek out the small birds known as honeyguides, the birds also actively seek out humans ensuring both species benefit, a new study shows.

Pioneering work by the Kenyan ecologist Hussein Isack in the 1980s confirmed honeyguides communicate reliable information to humans about the location of bees' nests, and this greatly increased honey-hunters' harvests, said the study's lead author Dr Claire Spottiswoode of the University of Cambridge in the UK and the University of Cape Town in South Africa.

In return, the greater honeyguide (Indicator indicator), which feeds from bees' nests, eating eggs, larvae and beeswax, relies on their human partner to crack open the hive.

"It's a remarkable example of cooperation between humans and a free-living wild animal," Dr Spottiswoode said.

But in a new study of the Yao honey hunters from Mozambique's Niassa National Reserve, published today in Science, Dr Spottiswoode and her colleagues show the interaction has an extra dimension.

Not only do the Yao honey hunters follow the birds' call to guide them to the hive, the birds themselves seek out the specific call made by the hunters to initiate the hunt.
© Claire N. Spottiswoode
Yao honey-hunters searching for honeyguides in the Niassa National Reserve, Mozambique.
"Yao honey hunters searching for honeyguides, or wanting to maintain a honeyguide's attention as they follow it through the bush, give at intervals a loud trill followed by a grunt — 'brrrr-hm!'," Dr Spottiswoode said.

"They make this sound only in this context, so it's a reliable signal to honeyguides that a human is looking for bees."

Gear

Soviet-born scientist stirs up a revolution in rotary engines in the U.S.

© Press photo
In 1975 Russian physicist Nikolai Shkolnik left the Soviet Union for the U.S. after graduating from the Kiev Polytechnic Institute. For 10 years he worked as a consultant for struggling innovation companies. Throughout these years, he was constantly preoccupied with one question - why are modern car engines so inefficient?

Shkolnik developed his own high-efficiency hybrid cycle (HEHC) engine, which became a key step towards his dream. He was helped by his son Alexander, who eventually graduated from MIT and had become an expert in system optimization.

Nikolai Shkolnik is convinced that, among other things, the education he received in the USSR helped his ambition to create a revolutionary engine.

"There are big differences between American engineers and those trained in Russia,'' said Shkolnik. ''American engineers are incredibly effective in what they do, and it usually takes two or three Russian engineers to replace one American. However, Russians have a broader view of things, which has to do with their education; at least in my time it did. They are capable of achieving goals with a minimum of resources."

Info

Viruses have been a major force driving our evolution


The constant battle between pathogens and their hosts has long been recognized as a key driver of evolution. Their findings suggest an astonishing 30 percent of all protein adaptations since humans' divergence with chimpanzees have been driven by viruses.
The constant battle between pathogens and their hosts has long been recognized as a key driver of evolution, but until now scientists have not had the tools to look at these patterns globally across species and genomes. In a new study, researchers apply big-data analysis to reveal the full extent of viruses' impact on the evolution of humans and other mammals.

Their findings suggest an astonishing 30 percent of all protein adaptations since humans' divergence with chimpanzees have been driven by viruses.

"When you have a pandemic or an epidemic at some point in evolution, the population that is targeted by the virus either adapts, or goes extinct. We knew that, but what really surprised us is the strength and clarity of the pattern we found," said David Enard, Ph.D., a postdoctoral fellow at Stanford University and the study's first author. "This is the first time that viruses have been shown to have such a strong impact on adaptation."

The study was recently published in the journal eLife and will be presented at The Allied Genetics Conference, a meeting hosted by the Genetics Society of America, on July 14.

Chalkboard

New modeling suggests Earth's supercontinents tore apart quickly after millions of years of strained separation

© MIKKEL JUUL JENSEN / BONNIER PUBLICATIONS / GETTY IMAGES
Around 175 million years ago, the ancient supercontinent Pangea began to break up. New research shows how the continents were sling-shotted off each other, thanks to their strained separation.
Earth's supercontinents spent millions of years under huge amounts of strain before abruptly lurching apart to form oceans between them, new modelling suggests.

A team at the University of Sydney in Australia revealed the underlying actions of the splitting landmass - a sustained period of slow inching apart followed by a sudden heave - in the journal Nature.

Dieter Mueller, senior author on the paper, likens the geological mechanics to pulling apart a thick piece of dough: "At first, separating it requires a lot of effort because the dough resists your pulling and stretches slowly between your hands.

"If you're persistent, you'll eventually reach a point where the dough becomes thin enough to separate quite easily and quickly."