Category: BBC News

Spitting fish adjust for distance when shooting

On By A.P.In BBC News, Current Biology, Jonathan Webb, Kebmodee, Peggy Gerullis, spitting fish, Stefan Schuster, University of BayreuthLeave a comment

archer fish
Footage captured by two high-speed cameras shows the fish’s ability in detail

The jets of water that archer fish use to shoot down prey are “tuned” to arrive with maximum impact over a range of distances, according to a study.

By Jonathan Webb
Science reporter, BBC News

High-speed cameras were used to analyse fishes’ spitting performance in detail.

As they create each jet, the fish tweak the flow of water over time, causing a focussed blob of water to gather just in front of the target, wherever it is.

The ability comes from precise changes to the animal’s mouth opening, which may prove useful in designing nozzles.

Senior author Prof Stefan Schuster, from the University of Bayreuth in Germany, explained that jets of water and other fluids are used to cut or shape materials in industries ranging from mining to medicine.

He believes his new fish-based findings could improve the technology.

Patience and precision
“I’ve never seen anything in which they use a nozzle that changes its diameter,” he told the BBC. “The most standard approach is adjusting the pressure.”

But pressure, which the archer fish apply by squeezing their gill covers together, is not the secret to their ballistic precision.

Prof Schuster and his PhD student Peggy Gerullis found no evidence for pressure adjustments, nor for chemical additives or flicking movements in the water, which might account for the fishes’ ability to control the stability of the water jet, and focus the accelerating blob at its tip.

“The fish add nothing – they only shoot water, and they keep absolutely still during release of the jet,” Prof Schuster said.

“They just do it with the mouth opening diameter. It is not a simple manoeuvre… The diameter is continuously changing.”

That makes the new study, published in Current Biology, the first evidence of an animal actively manipulating the dynamics of a water jet.

Prof Schuster and Ms Gerullis trained two archer fish to hit targets at distances from 20cm to 60cm, under bright lights to help with filming.

The targets were small spheres, which allowed the team to calculate the forces involved.

Accuracy, of course, was rewarded – usually with a small fly. “You can easily train a fish to shoot at anything you want,” said Prof Schuster. “They are perfectly happy as long as something edible falls down.”

The tricky part was organising the angles.

“To be ready to monitor to the right spots with reasonable spatial resolution, you have to convince the fish somehow to fire from a defined position. That was the hardest part of the study, actually.”

With patience, the researchers collected enough measurements to reveal that the all-important blob of water at the jet’s tip, which allows archer fish to dislodge their prey, forms just before impact – no matter the target distance.

To accomplish this, the animals fine-tune not just the speed, but the stability of the water jet.

“It means that the physics the fish is using is much more complicated than previously thought,” Prof Schuster explained.

Cognitive evolution?

Dynamic jet control must now be added to an already impressive list of this fish’s abilities.

Other research has explored questions ranging from how archer fish compensate for the distortion of their vision by the water surface, to how they learn to hit moving targets by copying their companions, to exactly how they produce a water jet that catches up on itself to form their distinctive, watery missile.

Prof Schuster believes that their spitting accuracy may have evolved in a similar way to human throwing, which some theorists argue sparked an accompanying expansion of our cognitive abilities.

His team has also done fieldwork in Thailand, where they observed that the fish hunt in daylight, when their insect targets are few and far between. So having a good range, and not missing, are a big advantage for survival.

That power and precision requires brain power.

“People have calculated that to double [throwing] range requires roughly an 8-fold increase in the number of neurons involved in throwing,” Prof Schuster said.

So are these fish evolving into the cleverest animals under water?

“I don’t think they will develop into humans. [But] they have many strange abilities that you wouldn’t expect from fish.

“Maybe we can show by looking more closely at the brain, that shooting might have played a similar, prominent role in driving these abilities, as it’s thought that throwing played in human evolution.

“That’s just a crazy idea of mine.”

http://www.bbc.com/news/science-environment-29046018

Thank to Kebmodee for bringing this to the attention of the It’s Interesting community.

Ancient Irish texts show volcanic link to cold weather

On By A.P.In BBC News, Climate Change, Cold, Dark Ages, Environmental Research Letters, Francis Ludlow, GISP2, Greenland Ice Sheet Project, Harvard, Harvard University, Ireland, Irish Annals, Kebmodee, Matt McGrath, Volcano, Weather2 Comments

irish volcano

By Matt McGrath

Environment correspondent, BBC News

Researchers have been able to trace the impact of volcanic eruptions on the climate over a 1200 year period by assessing ancient Irish texts.

The international team compared entries in these medieval annals with ice core data indicating volcanic eruptions.

Of 38 volcanic events, 37 were associated with directly observed cold weather extremes recorded in the chronicles.

The report is published in the journal Environmental Research Letters.

In the dim light of the Dark Ages, the Irish literary tradition stands out like a beacon.

At monastic centres across the island, scribes recorded significant events such as feast days, obituaries and descriptions of extreme cold and heat.

These chronicles are generally known as the Irish Annals and in this report, scientists and historians have looked at 40,000 entries in the texts dating from AD431 to 1649.

The researchers also looked at the Greenland Ice Sheet Project (GISP2) ice-core data.

When volcanoes erupt, they produce sulphate aerosol particles which down the centuries have been deposited on and frozen in ice sheets, leaving an extremely accurate temporal record of the event.

Scientists say these particles reflect incoming sunlight and can cause a temporary cooling of the Earth’s surface. In a country with a mild maritime climate like Ireland, these colder events would have a significant impact.

When the weather that is cold enough to allow you to walk over a lake in Ireland, it is pretty unusual,” lead author Dr Francis Ludlow, from Harvard University, told BBC News.

“When it happened, it was remarkable enough to be recorded pretty consistently.”

The scientists in the team identified 48 volcanic eruptions in the time period spanning 1,219 years. Of these, 38 were associated closely in time with extreme weather events identified in the Irish texts.

“These eruptions occur and they override existing climate patterns for a period of two or three years,” said Dr Ludlow.

“And it is clear from the sources that they cause a lot of devastation among societies at the time – whether it was the mass mortality of domestic animals or humans, or indirectly by causing harvest failure.”

The research team believe the texts are accurate as the annals also record solar and lunar eclipses which can be compared with other contemporary sources.

The keen recording of weather though had another motivation.

“A lot of these scribes are working in monasteries, in some time periods they are interpreting these weather events as divine omens or portents as signals of the coming of the last days,” said Dr Ludlow.

“That was one of their motivations so we are able to use the records that were created for a completely different purpose that the scribes would never have conceived.”

The researchers say that one expected effect of volcanic eruptions that occur in tropical regions is to make for milder winters in northern latitudes.

But in this study, they found several instances of these type of eruptions causing extremely cold winters in Ireland. The team believes their work shows the complex nature of volcanic impacts on climate, and they say there are lessons for the future in the ancient texts.

“That tells us a lot about what sort of weather we might expect in the British Isles when the next big eruption goes off,” said Dr Ludlow.

“We might want to buy a bit more salt for the roads.”

http://www.bbc.co.uk/news/science-environment-22786179

Thanks to Kebmodee for bringing this to the attention of the It’s Interesting community.

As the Earth warms, 400 year old frozen plants are being revived

On By A.P.In Algae, Bacteria, BBC News, bryophytes, Canadian Arctic, Catherine La Farge, Climate Change, cyanobacteria, environment, glacier, Global Warming, Little Ice Age, Nature, Proceedings of the National Academy of Sciences, Sverdrup Pass, Teardrop Glacier, The Future, University of AlbertaLeave a comment

plants

Plants that were frozen during the “Little Ice Age” centuries ago have been observed sprouting new growth, scientists say. Samples of 400-year-old plants known as bryophytes have flourished under laboratory conditions. Researchers say this back-from-the-dead trick has implications for how ecosystems recover from the planet’s cyclic long periods of ice coverage. The findings appear in Proceedings of the National Academy of Sciences.

They come from a group from the University of Alberta, who were exploring an area around the Teardrop Glacier, high in the Canadian Arctic. The glaciers in the region have been receding at rates that have sharply accelerated since 2004, at about 3-4m per year. That is exposing land that has not seen light of day since the so-called Little Ice Age, a widespread climatic cooling that ran roughly from AD 1550 to AD 1850.

“We ended up walking along the edge of the glacier margin and we saw these huge populations coming out from underneath the glacier that seemed to have a greenish tint,” said Catherine La Farge, lead author of the study.

Bryophytes are different from the land plants that we know best, in that they do not have vascular tissue that helps pump fluids around different parts of the organism. They can survive being completely desiccated in long Arctic winters, returning to growth in warmer times, but Dr La Farge was surprised by an emergence of bryophytes that had been buried under ice for so long.

“When we looked at them in detail and brought them to the lab, I could see some of the stems actually had new growth of green lateral branches, and that said to me that these guys are regenerating in the field, and that blew my mind,” she told BBC News. “If you think of ice sheets covering the landscape, we’ve always thought that plants have to come in from refugia around the margins of an ice system, never considering land plants as coming out from underneath a glacier.”

But the retreating ice at Sverdrup Pass, where the Teardrop Glacier is located, is uncovering an array of life, including cyanobacteria and green terrestrial algae. Many of the species spotted there are entirely new to science.

“It’s a whole world of what’s coming out from underneath the glaciers that really needs to be studied,” Dr La Farge said.

“The glaciers are disappearing pretty fast – they’re going to expose all this terrestrial vegetation, and that’s going to have a big impact.”

http://www.bbc.co.uk/news/science-environment-22656239

The Virtual Therapist

On By A.P.In Alastair Leithead, BBC News, California, Ellie, Institute for Creative Technologies, Jody, Louis-Philippe Morency, mental health, mental illness, Neuropsychiatric Disease, post-traumatic stress disorder, Psychiatry, psychotherapy, Skip Rizzo, The Future, University of Southern California, virtual psychotherapist, Wizard of Oz modeLeave a comment

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Ellie is a creation of ICT, and could serve as an important diagnostic and therapeutic tool for veterans with Post-Traumatic Stress Disorder.

By Alastair Leithead
BBC News, Los Angeles

The University of Southern California’s Institute for Creative Technologies is leading the way in creating virtual humans. The result may produce real help for those in need.

The virtual therapist sits in a big armchair, shuffling slightly and blinking naturally, apparently waiting for me to get comfortable in front of the screen.

“Hi, I’m Ellie,” she says. “Thanks for coming in today.”

She laughs when I say I find her a little bit creepy, and then goes straight into questions about where I’m from and where I studied.

“I’m not a therapist, but I’m here to learn about people and would love to learn about you,” she asks. “Is that OK?”

Ellie’s voice is soft and calming, and as her questions grow more and more personal I quickly slip into answering as if there were a real person in the room rather than a computer-generated image.

“How are you at controlling your temper?” she probes. “When did you last get into an argument?”

With every answer I’m being watched and studied in minute detail by a simple gaming sensor and a webcam.

How I smile, which direction I look, the tone of my voice, and my body language are all being precisely recorded and analysed by the computer system, which then tells Ellie how best to interact with me.

“Wizard of Oz mode” is how researcher Louis-Philippe Morency describes this experiment at the University of Southern California’s Institute for Creative Technologies (ICT).

In the next room his team of two are controlling what Ellie says, changing her voice and body language to get the most out of me.

Real people come in to answer Ellie’s questions every day as part of the research, and the computer is gradually learning how to react in every situation.

It is being taught how to be human, and to respond as a doctor would to the patients’ cues.

Soon Ellie will be able to go it alone. That opens up a huge opportunity for remote therapy sessions online using the knowledge of some of the world’s top psychologists.

But Dr Morency doesn’t like the expression “virtual shrink”, and doesn’t think this method will replace flesh-and-blood practitioners.

“We see it more as being an assistant for the clinician in the same way you take a blood sample which is analysed in a lab and the results sent back to the doctor,” he said.

The system is designed to assess signs of depression or post-traumatic stress, particularly useful among soldiers and veterans.

“We’re looking for an emotional response, or perhaps even any lack of emotional response,” he says.

“Now we have an objective way to measure people’s behaviour, so hopefully this can be used for a more precise diagnosis.”

The software allows a doctor to follow a patient’s progress over time. It objectively and scientifically compares sessions.

“The problem we have, particularly with the current crisis in mental health in the military, is that we don’t have enough well trained providers to handle the problem,” says Skip Rizzo, the associate director for medical virtual reality at the ICT.

“This is not a replacement for a live provider, but it might be a stop-gap that helps to direct a person towards the kind of care they might need.”

The centre does a lot of work with the US military, which after long wars in Iraq and Afghanistan has to deal with hundreds of thousands of troops and veterans suffering from various levels of post-traumatic stress disorder.

“We have an issue in the military with stigma and a lot of times people feel hesitant talking about their problems,” he says. A virtual counselling tool can alleviate some of this reluctance.

“We see this as a way for service members or veterans to talk openly and explore their issues.”

The whole lab is running experiments with virtual humans. To do so, it blends a range of technologies and disciplines such as movement sensing and facial recognition.

Dr Morency has won awards for his work into the relationship between psychology and minute physical movements in the face.

“People who are anxious fidget with their hands more, and people who are distressed often have a shorter smile with less intensity. People who are depressed are looking away a lot more,” he says.

Making computer-generated images appear human isn’t easy, but if believable they can be powerful tools for teaching and learning. To that end, the lab is involved in several different projects to test the limits and potential of virtual interactions.

In the lab’s demonstration space a virtual soldier sits behind a desk and responds to a disciplinary scenario as part of officer training.

The team have even built a Wild West style saloon, complete with swinging doors and bar.

Full-size characters appear on three projection screens and interact with a real person walking in, automatically responding to questions and asking their own to play out a fictional scenario.

Downstairs, experiments are creating 3D holograms of a human face.

Throughout the building, the work done is starting to blur the lines between the real world and the virtual world.

And the result just may be real help for humans who need it.

http://www.bbc.co.uk/news/magazine-22630812

Many thanks to Jody, for bringing this to the attention of the It’s Interesting community.

Maori stones hold magnetic clues

On By A.P.In AGU, American Geophysical Union, andesite, BBC News, Central North Island, Gillian Turner, hangi, Kebmodee, Magnetism, Maori, Maori steam ovens, Maori stones, New Zealand, radiocarbon analysis, Victoria University, Wellington, white hot heatLeave a comment

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Scientists are studying the Earth’s magnetic field using the stones that line Maori steam ovens.

The cooking process generates so much heat that the magnetic minerals in these stones will realign themselves with the current field direction.

An archaeological search is under way in New Zealand to find sites containing old ovens, or hangi as they are known.

Abandoned stones at these locations could shed light on Earth’s magnetic behaviour going back hundreds of years.

“We have very good palaeomagnetic data from across the world recording field strength and direction – especially in the Northern Hemisphere,” said Gillian Turner from Victoria University, Wellington, New Zealand.

“The southwest Pacific is the gap, and in order to complete global models, we’re rather desperate for good, high-resolved data from our part of the world,” she told BBC News.

Dr Turner was speaking here at the American Geophysical Union (AGU) Fall meeting, the world’s largest annual gathering of Earth scientists.

The NZ researcher is working on a project to retrieve information about changes in the Earth’s magnetic field stretching back over the past 10,000 years.

For data on the last few centuries, she would ordinarily have turned to pottery.

When these objects are fired, the minerals in their clay are heated above the Curie temperature and are demagnetised.

Then, as the pots cool down, those minerals become magnetised again in the direction of the prevalent field. And the strength of the magnetisation is directly related to the strength of that field.

Unfortunately for Dr Turner, the first settlers on New Zealand 700-800 years ago – the Maori – did not use pottery. However, the researcher has hit upon a fascinating alternative.

She is now exploiting the Maori cooking tradition of the steam oven.

These were pits in the ground into which were placed very hot stones, covered with baskets of food and layers of fern fronds soaked in water.

The whole construction was then topped with soil and left to cook for several hours.

Dr Turner and colleagues experimented with a modern-day hangi to see if the stones at the base of the pit could achieve the necessary Curie temperatures to reset their magnetisation – to prove they could be used as an alternative data source for their study.

“The Maori legend is that the stones achieve white hot heat,” she explained.

“Well, red hot is about 700 degrees and so white hot would be a good deal more than that. But by putting some thermocouples in the stones we were able to show they got as high as 1,100C, which of itself is quite surprising. At that temperature, rock-forming minerals start to become plastic if not melt.”

By placing a compass on top of the cooled hangi stones Dr Turner’s team was able to establish that a re-magnetisation had indeed taken place.

It turns out that hangi stones were carefully chosen, and one of the most popular types was an andesite boulder found in Central North Island.

“The Maori prefer these volcanic boulders because they don’t crack and shatter in the fire, and from our point of view they’re the best because magnetically they behave better – they’re formed with a high concentration of magnetite,” the Wellington scientist said. “But there are some sedimentary rocks which we can use also.”

Dr Turner’s team is now scouring New Zealand for archaeological digs that have uncovered hangi ovens. It is crucial that a date is recovered with the stones. This can be provided by a radiocarbon analysis of the charcoal left from the firewood used to light the oven.

Hangi stones are only likely to take Dr Turner back to the 1200s. For magnetic data deeper in time, she needs to go to other sources.

“We’re also studying volcanic rocks because they’re erupted above the Curie temperature. And the other source of information is lake sediments. Long-core sediments can give us a continuous record at specific places.”

http://www.bbc.co.uk/news/science-environment-20520454

Thanks to Kebmodee for bringing this to the attention of the It’s Interesting community.