Category: GCSE Physics

Harnessing Nature’s glow

The Light Fantastic: Harnessing Nature’s glow

http://www.bbc.co.uk/news/science-environment-21144766

By Paul RinconScience editor, BBC News website – Paul.Rincon-INTERNET@bbc.co.uk

 

Dinoflagellates

 

Living organisms may use bioluminescence for a variety of reasons, such as communication and display

Bioluminescence describes the light that some living creatures such as fireflies and jellyfish emit from their cells. Harnessing these reactions has already transformed key areas of clinical diagnosis and medical research.

But scientists are now looking at whether this “living light” could help enhance food crops, detect pollution or even illuminate our journeys home.

On a night in January 1832, off the coast of Tenerife, a young Charles Darwin wandered up on to the deck of the HMS Beagle.

As the young naturalist looked out to sea, he was struck by the unearthly glow emanating from the ocean.

“The sea was luminous in specks and in the wake of the vessel, of a uniform, slightly milky colour,” he wrote.

“When the water was put into a bottle, it gave out sparks for some minutes after having been drawn up.”

‘Natural light’

Fluorescence: Energy from an external source of light is absorbed and re-emitted. Fluorescence can only occur in the presence of this light source; it cannot happen in complete darkness.

Bioluminescence: The energy for light production comes from a chemical reaction in living cells, as opposed to the absorption of photons as happens in fluorescence.

Darwin was almost certainly describing the light emitted by tiny marine organisms called dinoflagellates. His accounts of this phenomenon, known as bioluminescence, were unearthed by Prof Anthony Campbell in hand-written notebooks stored at Cambridge University.

While Darwin was one of the first modern scientists to document the phenomenon, it would be more than a century before it was put to practical use. Prof Campbell, from Cardiff University, carried out pioneering research throughout the 1970s and 1980s leading to the discovery that living creatures produce this light using special proteins called luciferases. The proteins take part in a chemical reaction in the cells, which is responsible for the light emission.

“When I started researching bioluminescence 40 years ago at the [Cardiff University] medical school, a lot of people raised their eyebrows and said: ‘What the devil is this guy doing working on animals in the sea? He was brought from Cambridge to do medical research’,” Prof Campbell explains.

Huge market

But he was able to spot the phenomenon’s potential. Having discovered the proteins involved in bioluminescence, he realised that by combining luciferases with other molecules, it was possible to harness this light emission to measure biological processes.

Jellyfish
Bioluminescence could shed light on changes in the marine environment

This would pave the way for something of a revolution in medical research and clinical diagnosis.

For example, by attaching a luminescent protein to an antibody – a protective molecule produced by the body’s immune system – it could be used to diagnose disease. This allowed clinicians to dispense with the radioactive markers that had previously been used in such tests.

“This market is now worth about £20bn. If you go into a hospital and have a blood test which measures viral proteins, cancer proteins, hormones, vitamins, bacterial proteins, drugs, it will almost certainly use this technique,” Prof Campbell told BBC News.

Bioluminescent proteins are also tools in drug discovery and have found widespread applications in biomedical research, where they are used to study biological processes in live cells.

“If you’ve got a university department that doesn’t use these techniques, they are not at the cutting edge,” says Campbell.

Contamination problem

Other applications are on the horizon. At the University of Lausanne in Switzerland, Prof Jan van der Meer has developed a test for the presence of arsenic in drinking water using genetically modified bacteria.

Arsenic contamination of groundwater is a pernicious problem in some parts of the world, especially in Bangladesh, India, Laos and Vietnam.

Prof van der Meer’s microbes have been engineered to emit light when they come into contact with arsenic-containing compounds. Potentially contaminated water is injected into vials, activating the dormant GM bacteria. The extent to which the microbes emit light is then measured to provide an indication of arsenic concentrations in the water.

Glowing trees   Cambridge iGEM
Could glowing trees one day replace street lights?

The work is now being commercialised by the German firm Arsolux. Prof van der Meer says the bacterial-based kits cope well with multiple samples, require fewer materials than standard chemical testing field kits, and are easy to prepare.

But regulatory hurdles remain to the take-up of bacteria-based tests in these countries. And, Prof van der Meer adds: “In the end it comes down to market things… things you cannot control as a scientist.”

So called rainbow proteins (a spin-off from work into bioluminescence), which change colour in response to particular compounds, are also an option for detecting environmental toxins, or the potential agents of terrorism.

Plant potential

There are already several consumer applications of bioluminescence: one US firm has made use of it to manufacture luminous drinks for sale in nightclubs.

And researchers have even modified plants so that they emit light. Bioluminescent crops could indicate when they require water and nutrients, or warn of disease and infestation. However, the controversy surrounding GM foods has so far prevented these ideas from taking hold.

A few years ago, a team of undergraduates at Cambridge University researched the idea of luminescent trees that would act as natural “street lamps”.

“What we achieved in that project was to put together some DNA which allowed bioluminescence, to show that it worked in [the bacterium] E. coli, and to submit it to the ‘parts registry’ which holds this DNA so anyone else can use it in future,” team member Theo Sanderson told BBC News.

“We were approached about a year ago and offered funding to continue developing the project, but we have all gone on to other things and so it wasn’t really an option.”

Previous efforts to create light-emitting plants in the lab have made use of a luciferase gene derived from fireflies. But these plants can only glow when supplemented with an expensive chemical called luciferin. The method used by the Cambridge team is attractive because it is based on bacterial systems which produce their own fuels for luminescence and so can be fed normal nutrients.

FireflyGlowing plants have used a bioluminescent protein derived from the firefly

In 2010, a separate team published a study in which they were able to demonstrate that such methods could be used to create plants that glowed without the need for chemical supplements. The US-Israeli team of scientists inserted light-emitting genes from bacteria into the plants’ chloroplasts – the structures in their cells which convert light energy from the Sun into chemical fuel.

Mr Sanderson, who now works at the Sanger Institute near Cambridge, said this was a good choice because chloroplasts are essentially bacteria that have become incorporated into plant cells, so they can easily express the microbe-derived gene without the need for other modifications.

But researchers will need to find ways to boost the light emission from such lab organisms if GM trees are ever to light our way through the urban jungle.

Prof Campbell says the potential of luminescent proteins in drug discovery and medical research has not yet been fully exhausted and he is currently collaborating on a project to use luciferases to research Alzheimer’s disease.

Bioluminescent creatures might also provide a convenient means of studying environmental changes in the sea. Some animals obtain the light-emitting chemicals they need from the organisms they eat. So studying the interactions between these species might allow scientists to detect changes in marine food webs.

Despite the impact on clinical diagnosis and research, Prof Campbell points out that he has only ever received one grant to research bioluminescence. Nevertheless, he says it is a “beautiful example of how curiosity – quite unexpectedly – has led to major discoveries in biology and medicine. And it has created several billion dollar markets”.

 

Permanent link to this article: https://animatedscience.co.uk/2013/harnessing-natures-glow

Star is Caught Devouring a Planet

Star is caught devouring planet (from the BBC)

Artist's impression of a planet's destruction

Astronomers have found evidence for a planet being devoured by its star, yielding insights into the fate that will befall Earth in billions of years.

The team uncovered the signature of a planet that had been “eaten” by looking at the chemistry of the host star.

They also think a surviving planet around this star may have been kicked into its unusual orbit by the destruction of a neighbouring world.

Details of the work have been published in Astrophysical Journal Letters.

The US-Polish-Spanish team made the discovery when they were studying the star BD+48 740 – which is one of a stellar class known as red giants. Their observations were made with the Hobby Eberly telescope, based at the McDonald Observatory in Texas.

Rising temperatures near the cores of red giants cause these elderly stars to expand in size, a process which will cause any nearbyHobby-Eberly telescope planets to be destroyed.

“A similar fate may await the inner planets in our solar system, when the Sun becomes a red giant and expands all the way out to Earth’s orbit some five billion years from now,” said co-author Prof Alexander Wolszczan from Pennsylvania State University in the US.

Lithium boost

The first piece of evidence for the missing planet comes from the star’s peculiar chemical composition.

Spectroscopic analysis of BD+48 740 revealed that it contained an abnormally high amount of lithium, a rare element created primarily during the Big Bang 14 billion years ago.

 The discovery was made using the Hobby-Eberly telescope in Texas

Lithium is easily destroyed in stars, so its high abundance in this ageing star is very unusual.

“Theorists have identified only a few, very specific circumstances, other than the Big Bang, under which lithium can be created in stars,” Prof Wolszczan explained.

“In the case of BD+48 740, it is probable that the lithium production was triggered by a mass the size of a planet that spiralled into the star and heated it up while the star was digesting it.”

The second piece of evidence discovered by the astronomers is the highly elliptical orbit of a newly discovered planet around the red giant star. The previously undetected world is at least 1.6 times as massive as Jupiter.

Co-author Andrzej Niedzielski of Nicolaus Copernicus University in Torun, Poland, said that orbits as eccentric as this one are uncommon in planetary systems around evolved stars.

“In fact, the BD+48 740 planet’s orbit is the most elliptical one detected so far,” he added.

Because gravitational interactions between planets are often responsible for such peculiar orbits, the astronomers suspect that the dive of the missing planet toward its host star before it became a giant could have given the surviving massive planet a burst of energy.

This boost would have propelled it into its present unusual orbit.

Team member Eva Villaver of the Universidad Autonoma de Madrid in Spain commented: “Catching a planet in the act of being devoured by a star is an almost improbable feat to accomplish because of the comparative swiftness of the process, but the occurrence of such a collision can be deduced from the way it affects the stellar chemistry.

“The highly elongated orbit of the massive planet we discovered around this lithium-polluted red giant star is exactly the kind of evidence that would point to the star’s recent destruction of its now-missing planet.”

http://www.bbc.co.uk/news/science-environment-19332091

Permanent link to this article: https://animatedscience.co.uk/2012/star-is-caught-devouring-a-planet

‘Leap second’ lengthens weekend

‘Leap second’ Lengthens Weekend  (30th Jun 2012)

11:59
Wait a second: on Saturday night atomic clocks will read 23 hours, 59 minutes and 60 seconds.

The world is about to get a well-earned long weekend but don’t make big plans because it will only last an extra second. A so-called “leap second” will be added to the world’s atomic clocks as they undergo a rare adjustment to keep them in step with the slowing rotation of the Earth.

To achieve the adjustment, on Saturday night atomic clocks will read 23 hours, 59 minutes and 60 seconds before moving on to midnight Greenwich Mean Time.

Super-accurate atomic clocks are the ultimate reference point by which the world sets its wristwatches. But their precise regularity – which is much more constant than the shifting movement of the Earth around the sun that marks out our days and nights – brings problems of its own.

If no adjustments were made, the clocks would move further ahead and after many years the sun would set at midday. Leap seconds perform a similar function to the extra day in each leap year which keeps the calendar in sync with the seasons. The International Earth Rotation and Reference Systems Service (IERS) based in Paris, is responsible for keeping track of the gap between atomic and planetary time and issuing international edicts on the addition of leap seconds.

“We want to have both times close together and it’s not possible to adjust the Earth’s rotation,” Daniel Gambis, head of the Earth Orientation Centre of the IERS, told Reuters.

Gambis said the turning of the Earth and its movement around the sun were far from constant.

In recent years, a leap second has been added every few years, slightly more infrequent than in the 1970s, despite the long-term slowdown in the Earth’s rotation caused by tides, earthquakes and a host of other natural phenomena.

Adjustments to atomic clocks are more than a technical curiosity.

A collection of the highly accurate devices are used to set Coordinated Universal Time, which governs time standards on the worldwide web, satellite navigation, banking computer networks and international air traffic systems.

There have been calls to abandon leap seconds but a meeting of the International Telecommunications Union (ITU), the UN agency responsible for international communications standards, failed to reach a consensus in January.

“They decided not to decide anything,” said Gambis, adding that another attempt would be made in 2015.

Opponents of the leap second want a simpler system that avoids the costs and margin for error in making manual changes to thousands of computer networks. Supporters argue it needs to stay to preserve the precision of systems in areas such as navigation.

Britain’s Royal Astronomical Society (RAS) says the leap second should be retained until there is a much broader debate on the change.

“This is something that affects not just the telecom industry,” said RAS spokesman Robert Massey. “It would decouple timekeeping from the position of the sun in the sky and so a broad debate is needed.”

Time standards are important in professional astronomy for pointing telescopes in the right direction but critical systems in other areas, not least defence, would also be affected by the change. “To argue that it would be pain-free is not quite true,” Massey said.

In the meantime, Massey plans to use his extra second wisely this weekend. “I’ll enjoy it with an extra second in bed,” he said.

Taken from: http://www.guardian.co.uk/science/2012/jun/29/leap-second-lengthens-saturday-time

Permanent link to this article: https://animatedscience.co.uk/2012/leap-second-lengthens-weekend

Dark matter tracks could give earliest view of Universe

Researchers have come up with a way to glimpse the infant Universe by decoding the earliest ripples in its light.

They say this can be achieved by capturing the specific radio wavelength of 21cm from the heavens.

The trick is to tell the difference between 21cm waves from our galaxy and those from distant, ancient sources.

The fact that “dark matter” moved faster than normal matter in the early Universe should help amplify the distant signal, they report in Nature.

That could yield a look at the Universe when it was just 1% of its current age.

The scientists first revealed their 3-D computer simulations on Monday at the Gamma Ray Bursts in the Era of Rapid Follow-up conference, hosted by Liverpool John Moores University.

The current record-holder for the oldest object ever spotted is a galaxy named UDFy-38135539, seen in an optical image captured by the Hubble telescope. Its light escaped more than 13 billion years ago, when the Universe was already a youth of less than 700 million years.

Continue reading the main story

What is redshift?

Diagram of Doppler shift

  • The term “redshift” arises from the fact that light from more distant objects shows up on Earth more red than when it left its source
  • The colour shift comes about because of the Doppler effect, which acts to “stretch” or “compress” waves from moving objects
  • It is at work in the sound of a moving siren: an approaching siren sounds higher-pitched and a receding one sounds lower-pitched
  • In the case of light, approaching objects appear more blue and receding objects appear more red
  • The expansion of the Universe is accelerating, so in general, more distant objects are moving away from us (and each other, and everything else) more quickly than nearer ones
  • At cosmic distances, the shift can profoundly affect the colour – the factor by which the wavelength is “stretched” is called the redshift

Scientists measure these literally astronomical distances with the “redshift” of a given light source; it is a measure of how much the source’s light is stretched as it races away from us in the ever-expanding Universe.

UDFy-38135539 has a redshift of 8.55, but the new work shows promise for looking at stars and galaxies at a redshift of 20.

However, if it works, the view will be a statistical one – astronomers will not actually see individual stars and galaxies, but rather be able to estimate how many objects of what sizes were around in those early days.

But instead of seeing only the largest and brightest objects, as studies with telescopes such as Hubble typically do, it should work down to galactic haloes as small as a millionth the mass of the Milky Way’s halo.

“It’s very small galaxies from very far away; it’s completely hopeless to see them individually with any telescope in the next few decades,” said Rennan Barkana of Tel Aviv University, a co-author on the study.

“That’s why this is so interesting – it’s an indirect detection of the whole population of these galaxies, but it would be a very clear confirmation that these galaxies are there,” Prof Barkana told BBC News.

Dark materials

The 21cm wavelength arises from changes within the atoms of hydrogen, the Universe’s most abundant element, and one that can tell us much about the early Universe before heavier elements were formed.

A key insight lies in the different speed limits for dark matter and normal matter in the early Universe, first pointed out in a 2010 Physical Review D paper.

The early Universe was shaped in part by pressure waves – just like sound waves – created in the wake of the Big Bang. Like air molecules shifted around by sounds, these waves carried and distributed normal matter in regular patterns we can now observe.

Murchison Widefield Array Low-frequency radio telescopes such as the Murchison array could help spot the 21cm waves

But dark matter, because it does not interact with normal matter, was not swayed by the waves, responding only to gravity.

The distributions of dark and normal matter in the early Universe changes just where the matter – mostly hydrogen – ended up, in turn changing where the 21cm emission should come from, and how intense it should be.

Averaged over the sky, there should be a greater variation in this signal than we see locally, and the new paper makes the case that heating by X-ray radiation in those early days should make this statistical fluctuation even easier to spot.

Prof Barkana said that although there are no current radio telescope arrays designed to catch these 21cm waves, several are under construction that could be put onto the task.

“This whole subject of 21cm cosmology is about to open up; there are at least four different groups building radio telescope arrays focussing on about redshift 10,” he said.

“But until now no one has had the incentive to build an array optimised for this (redshift 20) wavelength range.”

 

http://www.bbc.co.uk/news/science-environment-18521713

By Jason Palmer Science and technology reporter, BBC News

Permanent link to this article: https://animatedscience.co.uk/2012/dark-matter-tracks-could-give-earliest-view-of-universe

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