The Event that Transformed Earth

Up until 2.4 billion years ago, there was no oxygen in the air. It took something big to change that – perhaps the biggest evolutionary leap of all.

If you could build a time machine and go back to Earth's distant past, you'd get a nasty surprise. You wouldn't be able to breathe the air. Unless you had some breathing apparatus, you would asphyxiate within minutes.

The Great Oxidisation Event (Credit: APIX / Alamy)

For the first half of our planet's history, there was no oxygen in the atmosphere. This life-giving gas only started to appear about 2.4 billion years ago.

This "Great Oxidation Event" was one of the most important things to ever happen on this planet. 

Without it, there could never have been any animals that breathe oxygen: no insects, no fish, and certainly no humans.

For decades, scientists have worked to understand how and why the first oxygen was pumped into the air. They have long suspected that life itself was responsible for creating the air that we breathe.

But not just any life. If the latest findings are to be believed, life itself was undergoing a tremendous transformation just before the Great Oxidation Event. This evolutionary leap forward may be the key to understanding what happened.

Earth was already 2 billion years old at the time of the Great Oxidation Event, having formed 4.5 billion years ago. It was inhabited, but only by single-celled organisms.

It's not clear exactly when life began, but the oldest known fossils of these microorganisms date back 3.5 billion years, so it must have been before that. That means life had been around for at least a billion years before the Great Oxidation Event.

Those simple life-forms are the prime suspects for the Great Oxidation Event. One group in particular stands out: cyanobacteria. Today, these microscopic organisms sometimes form bright blue-green layers on ponds and oceans.

Their ancestors invented a trick that has since spread like wildlife. They evolved a way to take energy from sunlight, and use it to make sugars out of water and carbon dioxide.

This is called photosynthesis, and today it's how all green plants get their food. That tree down your street is pretty much using the same chemical process that the first cyanobacteria used billions of years ago.

It was the cyanobacteria, pumping out unwanted oxygen, that transformed Earth's atmosphere

From the bacteria's point of view, photosynthesis has one irritating downside. It produces oxygen as a waste product. Oxygen is of no use to them, so they release it into the air.

So there's a simple explanation for the Great Oxidation Event. It was the cyanobacteria, pumping out unwanted oxygen, that transformed Earth's atmosphere.

But while this explains how it happened, it doesn't explain why, and it certainly doesn't explain when it happened.

The problem is that cyanobacteria seem to have been around long before the Great Oxidation Event. 

"They're probably among the first organisms we have on this planet," says Bettina Schirrmeister of the University of Bristol in the UK.

We can be confident that there were cyanobacteria by 2.9 billion years ago, because there is evidence of isolated "oxygen oases" at that time. They might date as far back as 3.5 billion years, but it's hard to tell because the fossil record is so patchy.

That means the cyanobacteria were busy pumping out oxygen for at least half a billion years before oxygen started appearing in the air. That doesn't make a lot of sense.

One explanation is that there were a lot of chemicals around – perhaps volcanic gases – that reacted with the oxygen, effectively "mopping it up".

But there's another possibility, says Schirrmeister. Maybe the cyanobacteria changed. "Some evolutionary innovation in cyanobacteria helped them to become more successful and more important," she says.

Some modern cyanobacteria have done something that, by bacterial standards, is remarkable. While the vast majority of bacteria are single cells, they are multicellular.

The individual cyanobacterial cells have joined up into stringy filaments, like the carriages of a train. 

That in itself is unusual for bacteria, but some have gone further.

"Many cyanobacteria are able to produce specialised cells that lose their ability to divide," says Schirrmeister. "This is the first form of specialisation we see." It's a simple version of the many specialised cells that animals have, such as muscle, nerve and blood cells.

Schirrmeister thinks multicellularity could have been a game-changer for Earth's early cyanobacteria. It offers several possible advantages.

On the early Earth, single-celled organisms often lived together in flat layers of gunk called "mats". 

Within each mat there would have been many different species of cyanobacteria, and a host of other things to boot.

A multicellular cyanobacterium would have one clear advantage compared to its single-celled rivals. 

It would find it easier to spread, because its larger surface area would mean it was better at attaching itself to slippery rocks. Such an organism would be "less likely to wash away in the current", says Schirrmeister.

Many modern multicellular cyanobacteria can move around within their mats. "They're not extremely fast but they can move," says Schirrmeister. That suggests the primordial ones could as well.

Moving could have helped them survive. At the time the Earth was being bombarded with harmful ultraviolet radiation from the Sun, and there was no ozone layer to keep it out.

"In modern mats, cyanobacteria will turn around and appear vertical instead of horizontal to protect themselves from excess sunlight," says Schirrmeister. "You have also movement between layers. It might be these multicellular cyanobacteria had the ability to position themselves optimally within the mat."

It's a neat idea. But for it to be true, cyanobacteria must have evolved multicellularity before the Great Oxidation Event.

Schirrmeister has spent the last few years trying to figure out when cyanobacteria first evolved multicellularity.

The clues lie in their genes. By examining genes that all cyanobacteria share, and identifying tiny differences between them, Schirrmeister could figure out how they are all related – essentially drawing up a family tree of cyanobacteria.

With that tree in place, Schirrmeister could then home in on the multicellular cyanobacteria, and estimate roughly when they first became multicellular.

Her first attempt, published in 2011, suggested that most modern cyanobacteria are descended from multicellular ancestors. That suggested multicellularity was ancient, but it was difficult to put a firm date on it.

Schirrmeister refined her methods for a second paper, published in 2013. This suggested that multicellularity evolved not long before the Great Oxidation Event, at a time when cyanobacteria were diversifying rapidly.

But that didn't clinch the argument. Her family tree was only based on one gene, albeit a gene shared by every single species of cyanobacterium. That meant the tree was suspect.

So Schirrmeister has now gone one better.

"This time I worked with 756 genes," says Schirrmeister. "The genes I took are present in all cyanobacteria."

Her estimate of the origin of multicellularity is still rough, but it seems to be around 2.5 billion years ago – before the Great Oxidation Event.

There are several different ways to calculate these family trees, and they all gave the same answer. "No matter how we calibrate our phylogeny, it seems more likely we have multicellularity evolving before the Great Oxidation Event," says Schirrmeister.

The results are published in Palaeontology.

This may not be the end of the story. Even if Schirrmeister's results are confirmed, and cyanobacteria did become multicellular just before the Great Oxidation Event, there are two big questions.

The first is, did multicellularity really offer them the advantages she thinks it did? We don't know, but we could find out: by testing how modern single-celled and multicellular cyanobacteria cope with different situations.

The second question is harder: why did it take so long for cyanobacteria to become multicellular? If it is so advantageous, why did they not evolve it sooner, and trigger an earlier Great Oxidation Event?

"The next step is to find out which genes are responsible for multicellularity in cyanobacteria," says Schirrmeister. "Then I could say why did it take that long, why didn't it evolve earlier." If lots of new genes were required, it becomes understandable that it took the cyanobacteria a long time to evolve it.

Whatever caused the Great Oxidation Event, it's clear that it is one of the most important things to ever happen on this planet.

In the short term, it was probably rather bad news for life.

"Oxygen would have been lethal for many bacteria," says Schirrmeister. "It's hard to prove, because from the fossil record we don't have a lot of deposits from that time… [but] we can assume we had a lot of bacteria dying at that point."

But in the longer term, it allowed a whole new kind of life to evolve. Oxygen is a reactive gas – that's why it starts fires – so when some organisms figured out how to harness it, they suddenly had access to a major new source of energy.

By breathing oxygen, organisms could become much more active, and much larger. Moving beyond the simple multicellularity developed by cyanobacteria, some organisms became far more intricate. 

They became plants and animals, from sponges and worms to fish and, ultimately, humans.

If Schirrmeister is right, those first multicellular cyanobacteria triggered the evolution of complex life, including us, by producing oxygen on a global scale. "It made complex life possible," she says.
Not bad for a bunch of tiny blue-green bacteria.

For more information visit:-

http://www.bbc.com/earth/story/20150701-the-origin-of-the-air-we-breathe

http://www.prlabs.co.uk/lab-supplies.php?N=gastube-carbon-dioxide-hr-05-20&Id=11735

Search for deadly asteroids must be accelerated to protect Earth, say experts

The search for deadly asteroids that could slam into Earth must be speeded up 100-fold to help protect the future of life on Earth, according to an influential group of scientists, astronauts and rock stars.

The call for action comes as experts around the world take part in Asteroid Day, an event on Tuesday marked by a series of talks and debates aimed at raising awareness of the existential threat posed by hurtling rocks from the heavens.

Lord Rees, the astronomer royal, and Brian May, from the rock group Queen, added their names to the 100X declaration, which calls for a rapid acceleration in human efforts to find and track potentially dangerous asteroids. Other signatories including Peter Gabriel, Richard Dawkins, Brian Cox and Eileen Collins, the first female commander of Nasa’s space shuttle.

“The aim is to ramp up public awareness and the awareness of governments to the fact that we are under threat from a meteor strike,” May told the Guardian. “It’s been made light of, and we’ve seen some great films, like Bruce Willis saving the day, but it is a very serious threat.”

Asteroid Day falls on the anniversary of an asteroid strike in 1908 that saw a 40 metre-wide lump of space rock enter the atmosphere over Tunguska in Siberia at about 33,500 miles per hour. The rock exploded mid-air and released the energy of a large hydrogen bomb, which flattened 2000 sq km of conifer forest.

Were an asteroid of the same size to slam into the atmosphere over London, the blast could destroy much of the capital within the M25. People in cities as far away as Oxford could be burned by the intense heat released in the explosion. In Scotland, the same blast would still have the force to blow peoples’ hats off.

From observations with ground-based telescopes, researchers know that of the million or so asteroids that could one day strike Earth, only about 10,000 are known and tracked. That means we are in the dark about 99% of the asteroids that have the potential to crash into the planet.

“They are clearly a threat and for the first time it is possible for us to do something to reduce that threat,” Lord Rees told the Guardian.

“It is now feasible to do a survey of all the potentially Earth-crossing asteroids above 50m in diameter, and objects like that impact Earth about once per century. One could then check their orbits to see if any are on a collision course with Earth and within 20-30 years have technology to divert any that are on course,” he added.

Huge asteroids several kilometres across are expected to hit Earth every ten million years or so. These can cause destruction on a global scale. A ten kilometre-wide space rock that crashed into what is now Mexico triggered a global catastrophe 68 million years ago which brought the reign of the dinosaurs to an end.

Since most of the Earth’s surface is covered by water, asteroids are more likely to arrive over the oceans. But these can be the worst impact sites for asteroids of about 300 metres wide. If one landed in the mid-Atlantic, it would produce a tsunami wave that could devastate cities on the east coast of the US, and along the coast of Europe.

“We know the rough numbers, we just don’t know when a particular asteroid is going to hit. If we are going to take precautions, we need to know the orbits of all of these bodies,” Rees said.

“The first thing is to do the survey to find out if there are any asteroids which seem to be on course with a high probability of hitting within the next 50 years. If we knew there was one on course to hit the Earth in next 50 years, that would focus minds on the technology.”

One mission, proposed by Nasa, aims to catalogue two thirds of the asteroids and other “near earth objects” that are larger than 140m and come close to Earth’s orbit. The NEOCam mission would use an infra-red camera to garner information on asteroid size, shape, rotation and composition. A private mission called Sentinel, which would put an another infra-red telescope in space, is being led by Ed Lu, a former space shuttle astronaut.

Scientists are actively looking at ways to protect Earth from any asteroids that do turn out to be on a collision course. One strategy is to crash a massive spacecraft into the asteroid and change its trajectory. Another option is a “gravity tractor”. In this scenario, a spacecraft flies alongside an inbound asteroid for long enough that its minuscule gravitational tug diverts the asteroid enough to pass Earth safely. Both could run into problems in a real situation, though: if the nudge does not work as expected, the asteroid may miss one city only to hit another.

The option to lob nuclear warheads at an incoming asteroid is appealing to Hollywood, but less so to many scientists, including May, who has a PhD in astrophysics.

“Blowing it up is probably not the greatest option, because you have a lot of fragments to deal with then, and it becomes rather random, but deflecting it one way or another seems to be an option,” he said.

“It’s absolutely possible there’s something out there of the magnitude that would wipe out a major city of the world, and that’s a very big thing: you’re talking about a human disaster on a vast scale.

“This is about saving us all. All the people on the planet, all the creatures on the planet, everything which we have built up and might be proud of. It’s a kind of insurance if you like,” he said.

For more information visit:-

http://www.theguardian.com/science/2015/jun/30/search-deadly-asteroids-protect-earth-brian-may-lord-rees

http://www.prlabs.co.uk/lab-supplies.php?N=urea-hydrogen-peroxide&Id=1606

Stain Removal - How Does it Work?

We’ve all struggled to get stains out of clothes – but do you understand the science behind this? Most stains are removed by dissolving them with a solvent. But which one do you use? Two factors should help you to decide this:

• The agent that is causing the stain
• The material that has been stained

Different solvents will dissolve different stains, however some solvents not only dissolve the stain, but also dissolve the material that is stained as well – something that you don’t want to happen! 

Click to enlarge

Stains can be roughly grouped into a few categories:

Enzymatic stains, such as blood, human sweat and grass stains, are mainly made up of proteins and can therefore be combatted by enzymes in stain remover formulations, such as proteases, lipases and amylases.

Oxidisable stains, like tea, coffee and red wine, which can be broken down by bleaching agents, like hydrogen peroxide.

Greasy stains, which can be attacked by lipase enzymes and surfactants. Compound Chemicals describes these as most commonly being "‘long carbon chain compounds with a charged water-soluble ‘head’ and an oil-soluble ‘tail’ (which) remove oil and grease by forming structures called ‘micelles’ around them.”

Particulate stains, such as soil stains, can be removed by ‘builders’ compounds, which remove positive metal ions from the water and help soften it, in turn removing calcium ions which often bind stains to fabrics.

So, next time you regret that wine spillage or try to take that grass stain out of a football shirt, you’ll know what’s going on behind that brightly coloured stain remover – the science of stains! 

For more information visit:-

http://www.prlabs.co.uk/lab-supplies.php?N=hydrogen-peroxide-6-wv-gpr-rectapur&Id=59163

http://www.compoundchem.com/2015/06/18/stain-removal/

https://en.wikipedia.org/wiki/Stain_removal

http://www.prlabs.co.uk/lab-supplies.php?N=ob-protease-solution&Id=62099

The Real Reason Sweet Tastes Sweet

You might think that the sweet taste of fruit is all down to those natural sugars. Think again, says Veronique Greenwood.

We tend to think of sugar as the supreme ruler of the sensation of sweetness. If an orange tastes sweet, it's because of the sugars it contains hit the sweet receptors in your taste buds. The same, it’s fair to say, should ring true for any other fruit, from blueberries to tomatoes.

But Linda Bartoshuk, a University of Florida taste scientist interviewed for this column before, and her colleagues think there is a different explanation. They've found that the chemicals responsible for a large chunk of the perception of sweetness in fruit are ones you smell – not the ones you taste.

Now, this is a different phenomenon than the old trick of plugging your nose while you eat a jelly bean and finding you can't identify its flavour. If you haven't done this, try it – it's a marvellous glimpse into how much of flavour isn't about the tongue. At first all you can taste is sweet, but when you open your nose, the sensation of strawberry or root beer or whatever the specific flavour is washes over you.

In the case of Bartoshuk and company's recent work, however, it isn't the complex overtones of flavour they are talking about. This is more fundamental. It's the sweetness itself.

Bartoshuk says that the idea that volatile compounds emanating from fruit could be linked to sweetness was being discussed in the 1970s. But the effects of individual volatiles were very small, and the amounts of each chemical in the fruit were small as well. “I knew that the issue existed, but I didn't think anything hot had been done on it, and I was right,” Bartoshuk says. A few years ago, however, while she and colleagues were working on a study attempting to dissect exactly which molecules are responsible for what you experience while eating a tomato, she found something surprising.

The team had analysed the make-up of 152 heirloom varieties of tomato, recording the levels of glucose, fructose, fruit acids, and 28 volatiles. At the same time, over the course of three years, they organised 13 panels of taste-testers to sample more than 66 of these varieties, rating each according to how much they liked it, its sweetness, its sourness, and other taste characteristics.

Bartoshuk still remembers the moment when she was sitting in her office with this mountain of data one afternoon and ran a test, out of curiosity, to see which compounds contributed most to sweetness. She was expecting the answer to be sugar, and it certainly was key, but “I about fell out of my chair,” she says. Also significantly contributing were seven volatiles.

Moreover, the volatiles seemed to account for why panellists had reported some tomato varieties to taste sweeter than others that had far more sugar. The team tested a variety called Yellow Jelly Bean, for instance, and another called Matina. The Yellow Jelly Bean has 4.5g of glucose and fructose in 100 millilitres of fruit and rated about a 13 on a scale used for perceived sweetness. The Matina has just under 4g but rated a whopping 25. The major biochemical difference between the two was that the Matina had at least twice as much of each of the seven volatiles as the Yellow Jelly Bean did. When the team isolated those volatiles from a tomato and added them to sugar water, its perceived sweetness jumped.

How sweet can a tomato be?

They've also investigated blueberries and strawberries, among other fruits. Strawberries have much less sugar than blueberries but are consistently rated much sweeter. Bartoshuk and colleagues suggest that this is because strawberries have so many more volatiles – something like 30 – than blueberries, which have “maybe three”, Bartoshuk estimates. They found that adding strawberry volatiles to sugar water boosted perceived sweetness even more than the tomato volatiles did, and adding volatiles from both together doubled it.

And it wasn't that an aroma of strawberries, or cherry tomatoes, was wafting up off the water. The volatiles weren't concentrated enough to float up and hit the nose. (Which is a good thing – one of the volatiles in tomatoes is isovaleric acid, which, on its own, smells like stinky cheese.) The more sugar there is, the less the volatiles contribute to sweetness. But the effect gets stronger, somehow, when greater numbers of volatiles are involved: even volatiles that aren't present in large amounts still seem to contribute to the sensation.

What is going here? Researchers are still investigating how and why the brain is blending this information. It's known that the signals coming from smell receptors activated by volatiles from the back of the mouth are shunted to the same part of the brain that handles taste, rather than being bundled with signals from the nose itself. Bartoshuk says. Though she is not a neuroscientist herself, she suggests that “in the brain, when you have volatiles affecting some of the same cells as taste, it integrates the message. And part of the integrating, for certain volatiles and certain tastes, is enhancement”.

While researchers continue to investigate the causes of this strange effect, we can daydream about the possibilities. Could you make fresh lemonade with less sugar if you tossed in a cocktail of volatiles? Possibly, Bartoshuk says, if you added many of them. She is also curious about the idea of breeding a fruit that's as sweet as it can possibly be. Could plant breeders analyse volatiles and select for strains that maximise this volatile effect? Bartoshuk thinks so.

For more information visit:- 

http://www.bbc.com/future/story/20150610-the-smells-that-make-sweet-sweeter

http://www.prlabs.co.uk/lab-supplies.php?N=d-fructose-for-biochemistry&Id=23318

http://www.prlabs.co.uk/lab-supplies.php?N=of-glucose-medium-20x10ml&Id=60555

The Chemistry of Stinging Nettles

Stinging nettles are a type of plant which have defensive hairs. Their stings hurt a lot. Stinging nettles can be found in all of America except Hawaii. They can also be found in most of Europe and in Asia. Nettles sting because the hairs on it contains poison. If nettles are heated the poison disappears, making it edible.



Click to enlarge

The excellent Compound Interest site once again shows us how something that has happened to most of us actually works.  The chemistry of stinging nettles and what can be done to counter act them.


Nettles have long been used for medicinal purposes.  Nettle leaf is a herb that has a long tradition of use as an adjuvant remedy in the treatment of arthritis in Germany. Nettle leaf extract contains active compounds that reduce TNF-α and other inflammatory cytokines. It has been demonstrated that nettle leaf lowers TNF-α levels by potently inhibiting the genetic transcription factor that activates TNF-α and IL-1B in the synovial tissue that lines the joint. 

Urtica dioica herb has been used in the traditional Austrian medicine internally (as tea or fresh leaves) for treatment of disorders of the kidneys and urinary tract, gastrointestinal tract, locomotor system, skin, cardio-vascular system, hemorrhage, flu, rheumatism and gout. 

Nettle is used in shampoo to control dandruff and is said to make hair more glossy, which is why some farmers include a handful of nettles with cattle feed. 

Nettle root extracts have been extensively studied in human clinical trials as a treatment for symptoms of benign prostatic hyperplasia (BPH). These extracts have been shown to help relieve symptoms compared to placebo both by themselves and when combined with other herbal medicines.

 

For more information visit:-

https://en.wikipedia.org/wiki/Urtica_dioica

http://www.compoundchem.com/2015/06/04/nettles/

On this day in History - Robert Koffler Jarvik was born

Robert Jarvik, MD is widely known as the inventor of the first successful permanent artificial heart, the Jarvik 7. In 1982, the first implantation of the Jarvik 7 in patient Barney Clark caught the attention of media around the world. The extraordinary openness of this medical experiment, facilitated by the University of Utah, fueled heated public debate on all aspects of medical research. But as doctors learned how to achieve excellent clinical outcomes in subsequent patients with the Jarvik 7, the press and public largely lost interest in the subject. As a result, outdated and erroneous accounts have made their way into mainstream discussions of the Jarvik 7 time and time again. 

Robert Jarvik

 Artificial Hearts in Context

In essence, two types of artificial hearts exist: the total artificial heart — which is implanted after the natural heart is removed — and the ventricular assist device — which is implanted to assist the natural heart, leaving the patient's own heart in place and still functioning.

"Removing a person's heart is one of the most dramatic surgical procedures one can imagine," says Dr. Jarvik, who began developing a tiny ventricular assist device, the Jarvik 2000, in 1988. "It is no surprise that more public attention is given to replacing a heart than to assisting one. But consider this question: If you had a failing arm or leg, would you rather have the best-possible artificial limb or a device that allowed you to keep your own arm or leg?"

The question is rhetorical. But while ventricular assist devices find wider application in patients than total artificial hearts, experts view the two as complementary treatments. For example, a total artificial heart is required when an assist device will not do, as in cases of biventricular failure when both sides of the natural heart falter.

In the 60s and 70s, mechanical hearts were being developed by the National Institutes of Health (NIH) but were largely unknown to the public. Then in 1967, Christian Bernard performed the first human heart transplant, an event that generated worldwide interest: People were suddenly aware of heart replacement as a way to treat a failing heart. In 1969, Denton Cooley performed the first implantation of a temporary total artificial heart, and the primitive device sustained the patient for almost three days until a donor was found through an urgent appeal in the press. After another decade and a half of NIH-supported research, the Jarvik 7 heart became the first total artificial heart implanted as a permanent replacement for a hopelessly diseased natural heart.

The First Jarvik 7 Patients

At the University of Utah on December 2, 1982, William DeVries, MD implanted the Jarvik 7 total artificial into Barney Clark, a Seattle dentist who volunteered to undergo the pioneering procedure because he wanted to make a contribution to medical science. Dr. Jarvik recalls that, before the surgery, Dr. Clark told doctors that he didn't expect to live more than a few days with the experimental heart, but he hoped that what the doctors learned might help save the lives of others someday.

Dr. Jarvik, who headed the company that manufactured the Jarvik 7 heart, agreed with University administrators to give no information to the press directly: no press releases and no interviews. Information would flow through the University press office, instead. The stated goal was to adhere to the highest ethical principles and to conduct this important medical research openly, with no effort to influence or restrict the press. Little press was desired or expected. The University held a briefing before the historic surgery, and attendance was moderate.

"The news about Barney Clark stunned the doctors by making headlines around the world", Dr. Jarvik says. "Enormous public interest developed, and hundreds of reporters converged on Salt Lake City to cover the story, and the University began to give them daily briefings, which were completely uncensored. All medically significant events in the post-operative course were reported, successes and setbacks alike."

The briefings were educational and contained much medical information, including explanations of basic physiology, interpretations of laboratory tests and x-rays, and lengthy question-and-answer sessions. All of the complications were fully reported, as well as the effectiveness of the mechanical heart at maintaining Dr. Clark's normal blood flow and sustaining his life.

"The sheer volume of information and the extraordinary degree of transparency created a sort of medical experiment in a fishbowl," Dr. Jarvik says. The University of Utah achieved its research and educational goals, but the press coverage seemed to leave its readers with unreasonable hopes and expectations: Many began to believe that artificial hearts would soon be commonplace and all but solve the problem of heart disease. The intense attention also attracted critics who apparently knew nothing of Dr. Clark's generous intentions and labeled him a "human guinea pig." Later, Dr. Clark's widow attempted to change this misimpression in order to give her husband the humanitarian credit he deserved. But Mrs. Clark received much less press than the critical commentary, and her mission ultimately foundered. Before another case could be conducted, Dr. DeVries, the surgeon, accepted an offer to join the research program at Humana Hospital in Louisville, Kentucky, and took his expertise there.

The next several implantations of the Jarvik 7 heart, conducted by Humana — a national hospital chain — were handled like the first: with the release of extensive medical information and an open press policy. The second Jarvik 7 implant took place in 1985. Bill Schroeder, the patient, did so well initially that when President Ronald Reagan phoned him with get-well wishes a week later, he asked the president why his social security check was late. (It was hand-delivered the next day.) Mr. Schroeder gave optimistic interviews to reporters and even joked that his noisy drive console "sounded like an old fashioned thrashing machine." But only two weeks after surgery, he suffered a serious stroke that left him unable to speak. Mr. Schroeder later moved from the hospital and lived with his wife in a nearby apartment, which had been outfitted with the special equipment he needed, including an air compressor and emergency generator. When traveling, he used a portable, compressed-air power system, which weighed about fifteen pounds. During his time on the Jarvik 7, he visited his hometown in Indiana and rode down Main Street in a parade, attended a basketball game, and went fishing, but in a limited way: He had many medical problems, including other serious strokes and infections. In all, Mr. Schroeder lived 620 days with his heart function restored but handicapped by his complications.

Three other patients received the Jarvik 7 heart for permanent use over the next year — two more in Louisville and one in Sweden. One patient died of bleeding a week following the operation; the others lived 10 months and 14 months. As it turned out, the Swedish patient was a man accused of tax evasion, but after his heart was removed, he was declared legally dead because under Swedish law, a person was dead when his or her heart stopped beating. The charges against him were officially dropped. The day he received the news, the patient was elated: He joked to his doctors that the old saying about nothing being certain but death and taxes isn't true.

The Jarvik 7 Today

After the first five permanent cases, the Jarvik 7 heart became more widely used as a temporary total artificial heart, bridging patients to transplant. The sixth patient lived five years after a donor heart was found, and the seventh patient lived eleven years with his donated heart. Another patient was bridged from the Jarvik 7 heart to a human heart that gave him fourteen more years of normal life. The press was unaware of these successes, or perhaps considered the subject old news, which, Dr. Jarvik says, was "more than fine" with the doctors involved. But as time went on, the press began reporting erroneously that use of the Jarvik 7 heart had halted after the first five. Later this turned into reporting erroneously that the Food and Drug Administration (FDA) had banned its use. Still later, this turned into reporting erroneously that the Jarvik 7 heart was a failed experiment: 

The press had begun to believe its own errors.

Since 1982, more than 350 patients have used the Jarvik 7 heart, and it remains in use today. The first few patients lived an average of 10 months (when their life expectancy was only days to weeks). Complication rates were high. "That's where the press stopped doing research and checking facts and instead began to publish mistake after mistake after mistake," Dr. Jarvik notes. All aspects of the experience, from the role of public funding of the research, to the ethics of human experimentation, were debated, but often on a foundation of misinformation. Newspaper and magazine articles with outdated and mistaken accounts appeared. Books with numerous errors were published. In the meantime, doctors gained experience with the Jarvik 7 and learned how to manage their patients more effectively and with fewer complications.

"Knowledgeable doctors watched with amazement as glaring errors appeared in print and then were repeated again and again as newspapers and magazines copied earlier stories and each other and didn't take the time to get information from original sources," says Dr. Jarvik. "Very rarely did I receive a phone call to check the facts. For example, the press wrote repeatedly that Dr. Clark died of a stroke. In fact, he never had a stroke at all. The press wrote over and over that the console a patient needed to power the heart was 'as large as a refrigerator.' In fact, the home console is about half that size, but more significantly — the portable power system was only the size of a briefcase."

And there's more, says Dr. Jarvik. "The press also wrote that the Jarvik 7 heart caused a high rate of strokes and infections. The press didn't notice that as more cases were done, these rates plummeted, yet the device was the same. So the device alone was never responsible for the earlier complications. Rather, doctors needed to learn how to manage their patients more effectively: That is the point of such research in the first place."

Perhaps the most glaring error of all is one that pops up from time to time in the diatribes of some self-proclaimed pundits: that the Jarvik 7 heart was a failed experiment. In fact, it has achieved the highest success rate of any type of artificial heart or assist device that has ever been developed.  Today, the Jarvik 7 heart is available at about ten medical centers in the United States, Canada, France, and Germany under the name CardioWest total artificial heart. (Ownership has changed hands several times, but the device 

design remains essentially unchanged.)

For more information visit:-

http://www.jarvikheart.com/basic.asp?id=69

http://en.wikipedia.org/wiki/Robert_Jarvik

When will we find aliens?

For the first time in human history, we have the means to answer the question.

Chris McKay's quest for extraterrestrial life started in 1976, when Viking 1 and 2 landed on Mars. Touching down on Mars for the first time was a big deal, sure, but the then-first-year graduate student was especially excited because the landers found what appeared to be signs of Martian life.

The spacecraft found that something in the dirt - possibly microbes - was taking in nutrients and producing gases like carbon dioxide. But when instruments failed to find any organic molecules, which are the building blocks of any organism, scientists concluded that no, aliens weren't living in the dirt.

To this day, however, scientists like McKay are still baffled by the Viking data, which never conclusively supported the existence of life, but were tantalizing nevertheless. For McKay, now a planetary scientist at NASA Ames Research Center, those results launched a career in astrobiology, despite the warnings of other scientists at the time. "Not only did they tell me not to," he says, "they made fun of me for being interested in it."

Four decades later, he's enjoyed some vindication. As robotic space probes continue to explore the solar system, visiting planets, moons, and asteroids, they're finding watery environments where microbial life could grab hold. Science can actually apply itself to the question instead of it being purely philosophical.

Outside the solar system, astronomers have discovered thousands of worlds - and they estimate our galaxy alone could be filled with hundreds of billions of planets. Many could be similar to Earth, with oceans, an atmosphere, and, yes, life.

In the coming decades, new space probes and telescopes will search for signs of life in the solar system and beyond. "We have a decent chance for finding Earth-like planets and evidence for life by sometime in the early 2030s," says Jim Kasting, a planetary scientist at Penn State University in the US.

Telescopes are used to eavesdrop on distant civilisations

And for the first time in human history, scientists have a plan and the means to answer the question of whether we're alone. "The fact that science can actually apply itself to the question instead of it being purely philosophical is very exciting," says Jason Wright, an astronomer also at Penn State. "It might be a long shot that we can do this, but the question is so compelling."

Undoubtedly, the most exciting kind of alien life would be the intelligent kind: the ETs or the ones depicted in Carl Sagan's novel Contact. Despite Roswell and Area 51, such close encounters have yet to happen. But scientists have been searching for decades, trying to eavesdrop on radio signals from a distant civilisation. Today, for example, the SETI Institute listens with the Allen Telescope Array in California.

Most recently, Wright led a hunt for super-advanced civilisations that have colonised an entire galaxy. In the 1960s, the physicist Freeman Dyson suggested that aliens could power their civilisation using energy from their planet's star. Consuming that energy - to run computers, spaceships, or whatever aliens might need - will radiate heat, like how your laptop gets warm. If such a civilisation took over a galaxy, then you could recognise it by searching for galaxies that radiate more heat than expected.

After scouring through images of 100,000 galaxies taken with the WISE satellite, Wright's team came up with nothing. But that's just for the extreme case of a super-advanced, galaxy-conquering alien. Maybe aliens stayed local. To find out, he says, the next step would be to study the galaxies in more detail, to see if certain regions within each galaxy are producing extra heat. "That would be very unusual," he says. "I don't know how we would go about getting a natural explanation for that."

Still, the search for intelligent life remains a reach. After all, life has flourished on Earth for about 3.5 billion years, and intelligent life (if we consider humans to be intelligent) has been around only for the last 200,000. For most of Earth's history, life consisted of primitive microbes. If we're ever to find life elsewhere, it will probably be microbial. Some could even be in our own cosmic backyard.

One intriguing place to look for life is on Titan, Saturn's largest moon. It's got a thick atmosphere and is the only other place in the solar system covered in seas and lakes - only they're filled with liquid methane, not water. Scientists think liquid is important for life, but the fact that it's methane means any Titanian critters would be fundamentally different from any Earthling.

That doesn't make life impossible, just maybe less probable. Life on Titan would also have to survive frigid temperatures of about -180 degrees C.

For life as we know it, the most important ingredient is still liquid water. And spacecraft are discovering the solar system to be quite wet. In March, observations with the Hubble Space Telescope suggested that an ocean lurks beneath the surface of Jupiter's largest moon, Ganymede. Right now, the Dawn spacecraft is orbiting Ceres, a dwarf planet in the asteroid belt that's 40 percent water by volume, including a possible subsurface ocean.

Among the most promising abodes for life are Mars, Saturn's moon Enceladus, and Jupiter's moon Europa. On Mars, the best chance for life might have been in the past, when the planet was warm and filled with rivers and lakes. Today, Mars is barren and likely inhospitable.

Microbes might, however, be able to eke out an existence below the surface. "I'd say it's 50/50 as to whether there's life on Mars right now," Kasting says. If there is, though, he says it's probably buried as deep as a kilometre underground, where temperatures are warm enough for water to be liquid. Getting there and finding proof, however, might require astronauts drilling on Mars.

Detecting life on Europa might also require drilling. A thick layer of ice maybe several kilometres deep encloses a potentially habitable ocean. Scientists have wanted to go to Europa for years, and they may soon get their chance. The White House's requested budget for 2016 includes $30 million for such a mission. But landing and drilling is difficult and expensive, so if the mission comes to fruition, it will probably study the world from space.

Which is why McKay thinks Enceladus - which also might have a subsurface ocean - is a better bet. "As people realise how difficult Europa is and how inaccessible its ocean is, they're going to be naturally attracted to Enceladus," says McKay, who was part of a team that recently proposed a NASA mission to Enceladus.

The icy moon became a top destination in 2009 when the Cassini spacecraft discovered plumes of water shooting hundreds of kilometres into space. Those plumes, spraying straight from the ocean below, could contain telltale signs of life. "You fly through the plumes from Enceladus," McKay says. "That gives you the best chance of detecting life." No drilling required.

Such an alien-hunting spacecraft would look for two types of molecules: lipids and amino acids. Lipids include fats and oils, and are important for the structure and function of cells. Amino acids are the building blocks of proteins.

The thing about an amino acid is that it can come in two versions that are mirror opposites of each other, like a left and right hand. Of the 20 amino acids that make up life on Earth, 19 are left-handed. Maybe, the thinking goes, amino acids that are biological in origin must generally have the same handedness. Discovering such molecules would certainly suggest life. "That's a grand slam," McKay says.

Still, he admits, that's a fantasy scenario. Microbes might not reveal themselves so easily, or they might not be there at all. Space missions take time and money, so if one spacecraft doesn't find anything, you'd have to wait years for another shot.

Chances might be better outside our solar system, among the billions of other planets in the galaxy. While a mission within the solar system can visit only one place at a time, a space telescope can easily go through dozens or even hundreds of potentially habitable worlds. Instead of lipids and amino acids, such telescopes will look for other molecules: oxygen and other gases that reveal living, breathing aliens.

Building off the resounding success of the Kepler space telescope, which has found thousands of planets, NASA will launch its Transiting Exoplanet Survey Satellite, or TESS, in 2017. Like Kepler, TESS will search for planets that pass in front of their stars, causing a slight dip in starlight. But unlike Kepler, TESS will target planets closer to Earth, and therefore easier to study and detect life.

What's got alien hunters excited is that TESS will find targets for the James Webb Telescope, which, after launching in 2018, will search those planets for atmospheric gases indicative of life.

The idea is this: As a planet passes in front of its star, some of the starlight will penetrate the planet's atmosphere, which appears as a thin outline surrounding the disk of the planet. Depending on its chemical composition, the atmosphere will absorb certain wavelengths of light. By measuring which wavelengths of light get through, astronomers can identify the gases in the atmosphere.

Astronomers have already studied planetary atmospheres with Hubble, showing their methods are sound. With the more powerful JWST, however, they can analyse atmospheres in greater detail.

One of the gases they hope to find is oxygen, which doesn't sit around very long before reacting with other compounds. So to maintain a lot of oxygen in its atmosphere, a planet would need something to replenish it - something living. On Earth, plants and bacteria do the job.

Compared to Mars or even Enceladus, this could be the most likely way scientists find life. "If I was betting today, I would bet on oxygen on an exoplanet," McKay says.

But oxygen is just one gas. Earthlings, for example, produce thousands (just think of all the smells that people, animals, and plants make). Only a handful of them are abundant enough to be detectable from space, however, so astronomers are figuring out which ones could be realistic indicators of life. Some proposed so far include methane and dimethyl sulfide, which phytoplankton produce on Earth.

Of course, finding life won't simply be a matter of detecting gases. Non-living things - such as thermal vents and volcanoes - can spew out many of the same compounds. To determine whether a particular gas is biological in origin, astronomers will have to study the chemistry and the specific properties of the planet.

Even then, short of a message from ET, astronomers may only be able to give the odds for extraterrestrial life. "We won't be sure there's life there, but we may be able to work through all the scenarios and assign a probability," says Sara Seager, an astronomer at MIT.

Another issue is that no one knows what alien life really looks like, so the proposed biosignatures so far are based on Earth's life. "You don't want to be too targeted and only look for stuff like Earth," Wright says. "But you also can't be so general that you have no idea what you're looking for."

To go beyond Earth-based life, Seager wants to identify any and all gases that could be stable and abundant in an atmosphere, regardless of whether anything on Earth makes them. To see if they're viable biosignatures, she will work backwards, reverse engineering biological processes that could produce those gases.

If JWST is to detect life, it will have to get lucky. The telescope was proposed years before astronomers knew the galaxy had billions of planets, so it wasn't designed for planet or alien hunting.

TESS will find thousands of plants, but only some will be good targets for JWST. A suitable planet can't be too small compared to its star. Otherwise, the glare of such a bright star swamps the image, and you can't see the subtle signal from the atmosphere. According to Seager, observing a planet next to its star is like picking out a firefly next to a searchlight from 1,500 kilometres away.

"It's not going to be easy," she says. "We're only going to have a handful of planets to search for signs of life on."

TESS and JWST will also be limited because they can only study planets that pass in front of their stars, which requires a perfect alignment. If JWST fails to find anything, astronomers will have to wait for a specially designed telescope that doesn't rely on transits.

Such a telescope will observe a planet directly, but for that to work, something will have to block the light from the planet's star. One idea called Starshade, which Seager has worked on, is a spacecraft that unfolds like a parasol to block starlight, allowing a separate space telescope to peer into the planet.

The telescope will be able to observe an Earth-sized planet orbiting a sun-like star, something TESS can't do because the brightness of a sun-like star will overwhelm the planet. With more potentially habitable planets - and including truly Earth-like planets - the chances for detecting life improve. "For a direct-imaging telescope, I'd say the odds are pretty good," Kasting says.

If anything, the sheer number and diversity of planets is reason for optimism in the quest for extraterrestrial life. "We know that atmospheres are out there, we've studied many of them, so the possibility is out there for the first time ever," Seager says. "It would be foolish not to take this opportunity."

For more information visit:-

http://www.bbc.com/earth/story/20150429-will-we-find-aliens

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