Friday, 30 March 2012

Here are ways that you look at those who are watching you on the Internet

It would be good to sometimes spy on them that spies on the Internet! Surely this is thought of ... as well as most ordinary net users. Firefox Mozilla web browser, in that sense, offer a solution.

Firefox launched the first version
collision extensions, which enables real-time know who follows a particular Internet users on the Internet and collects its data, according to a Mozilla site. In this way they want to help people how and why they followed on the Internet. This would be helped in changing habits on the Internet, consider Firefox creators.

 Namely, it is a tool through which you can see how different network locations follow a "trace" your service motion. The sites visited are marked points, surrounded by rings of gray, while the red rings indicate the locations that have used cookies from your web browser, that various portals and used by third parties to track your activities.

The background is of course all business and earnings, and that is why monitoring and therefore in most cases. So your Internet habits follow advertisers, to send advertising messages directed where they - or not expect, or want.

Wednesday, 28 March 2012

Facebook adds "Interest Lists"

Facebook will soon put "Add Interests" menu option that allows its users to log on to the subject content of feeds, the company said.

"Interest" is characterized by public figures, and pages that are associated with a particular theme common to people like you said in post on the Facebook site.

Facebook corps Isniq can join existing lists or create your own by adding any person or "Pages" pages that match the theme. The items in the list then appear in the "news" feeds.

Facebook says that in this way transforms the service "personalized newspapers" that represent different sections.

Monday, 26 March 2012

NASA: The man on the moon was really!

The steps that Buzz Aldrin and Neil Armstrong made ​​the lunar surface are still visible as a dark outline according to the latest photo released by NASA.

The photo next to the famous footprints can be seen the remains of their equipment, such as the lunar module and camera left behind by the astronauts after the 20th visit to the Moon July 1969th

Picture of landing Apoloa 11 caught with a height of 15 kilomegtara and the best way of showing "the best view of humanity's first steps in the discovery of another world," the statement issued by NASA.

Saturday, 24 March 2012

Russians and Koreans clone mammoth

If scientists succeed in the enterprise, the elephant in a few years could bring the baby into the world long since extinct.

This week in Seoul signed an agreement on scientific enterprise that looks more like a science fiction movie script, but if successfully executed will again walk the earth species extinct thousands of years ago.
Northeastern University Russian Federation and South Korean Foundation for Bioengineering "Suam" hoping that in six years to make the world a living mammoth.
This type of giant elephant lived on earth millions of years. Before the eight millennium have disappeared from most of all, they survived the longest in northern Siberia, where they became extinct about 2000 years ago. Due to the cold climate there are also the best preserved specimens, so the task of Russian scientists to provide quality material from which will be preserved DNA sample extracted. They would be the end of the year should be sent to Seoul remains found in Siberian permafrost melting, the ground under the perpetual snow and ice. South Koreans believe they have the knowledge and expertise to perform the cloning procedure and will help Russian counterparts, who are reviving the mammoth number of years worked with Japanese scientists. The venture will also participate in the Beijing Institute of Genetics, told the AFP.
Seoul is the team leader of the controversial scientist Hwang Woo Suk who was ten years ago, celebrated as a national hero as the world's first cloned dog, but then embarrassed because it turned out that most research on cloning human cells falsified. Then it lost its license, but continued to conduct experiments. Last year in October announced that it had successfully cloned a coyote and announced that his next venture will be a mammoth.
The plan is to be the core of the Indian elephant cell nucleus replacement cells wollen mammoth (Mammuthus primigenius). Then the embryo is inserted into an elephant, in this case the "surrogate mother". The Korean Institute says that 22 months later, the world should have the reputation of wollen baby mammoth.
Director of the Institute Snag Hwan Hyun explains the "Wall Street Journal" that this idea popular among geneticists since the late nineties, but now have the knowledge in the field of cloning, which gives them an advantage over other international scientific centers. The biggest question is whether it can provide high-quality genetic material, because the issue remains that are thousands of years under the ice.
If the project is successful, it will be the second time that an extinct animal "resurrected". Iberian ibeks, type of wild goat, which disappeared 2000th years, was cloned three years ago from the frozen skin cells. The surrogate mother was a domestic goat, but the baby died at birth due to problems with the lungs, which had other cloned animals.

Antifreeze in the mammoth blood

Two years ago, Australian, Canadian and Danish researchers "produce" the blood of a Siberian mammoth wollen and found that it acted as a kind of antifreeze.

They used DNA from the bones of a mammoth 43 ​​000 years old and is copied to cell bacteria E. coli, which produced the authentic mammoth protein.

Research has shown that the evolution has been a mammoth-specific changes in the blood so that it can carry oxygen to all cells at very low temperatures, which is the type that comes from Africa and enable it to survive in the Arctic.

Thursday, 22 March 2012

Nokia 808 has a 41 megapixel camera

The camera phone Nokia 808 Pure View of 41 megapixels for now has no competition - the group's professional cameras that cost several thousand dollars.

The Nokia has Symbian operating system and will cost around 450 euros, a market will appear in May.

Innovative camera will probably become part of the other phones in this house.

Nokia's new mobile phone is just one of many new devices that have been presented at the World Mobile Congress in Barcelona, the annual event to present innovations.

Tuesday, 20 March 2012

Atom of antimatter was measured for the first time!

A team from the European Organization for Nuclear Research (CERN) announced that the first time in history, measured some properties of atoms of antimatter, reports the site, "Live Science". In the experiment, "ALPHA" at CERN, scientists were able to measure anti-hydrogen atom - the simplest antimatter atom and hydrogen antipodes.

It is a "modest measurement," said the scientists, but also add to what others close to discovering the secrets of antimatter.

The researchers compared the characteristics of hydrogen atoms and anti-hydrogen and found that they are very similar. However, precise comparisons are yet to come, and scientists hope that this will better understand the nature of antimatter.

"We live in a universe that is the highest percentage consists of matter, but at the time of the Big Bang, matter and antimatter are likely to exist in the same amount. The mystery is what antimatter is now almost completely disappeared, leading to the conclusion that nature is still given a slight advantage over the matter, antimatter. If we can anti-hydrogen studied in detail, as these results suggest, we can get a powerful tool to explore the advantages of matter, "said the report.

Hydrogen atoms are the simplest in the universe and are believed to have formed during the Big Bang when the universe.

In the experiment, "ALPHA" scientists in June last year, finally managed to "capture" atoms anti-hydrogen and "keep them alive" and to fifteen minutes. It's outstanding achievement, considering that the atoms of antimatter disappear after a fraction of a second when touching the matter.

Antimatter is made up of elementary antiparticles, which have the same mass as the elementary particles that constitute matter. When touched, antimatter and matter, and cancel one another creating pure energy.

The report of the discovery was published in the scientific journal "Nature."

Sunday, 18 March 2012

Do you know 3D Satellite P855 laptop?

The company Toshiba has introduced 3D Satellite P855 laptop for the use of which will be needed special glasses ...

3D Satellite P855 laptop has a 15.6-inch screen, an Intel processor and graphics card Nvidia GT 630. There are speakers and Harman Kardon, a casing is lined with brushed aluminum.

Lenticular lenses and 3D web camera follow the movements of the eyes of customers and align the image on the screen depending on where users are seeing.

The company introduced this technology in 2011th The F750 laptop Cosmo 3D.

Friday, 16 March 2012

Oxygen Found on Saturn's moon

Oxygen was detected in the upper atmosphere of Saturn's moon Dione one of the 62 celestial bodies orbiting around a sixth of the "rock" around the sun.

The discovery came on the instrument spacecraft "Cassini" - which was launched 1997th year - called the "Cassini Plasma Spectrometer," flyover during the months of 2010. year.

This tiny moon is only 1.126 kilometers in diameter, and seems to be made of thick ice that surrounds the core bit. Around Saturn visit every 2.7 days and was constantly bombarded by ions ejected powerful magnetosphere of its planet. They hit the surface of Dione, releasing molecular oxygen ions, to be sucked Saturn again due to ourselves.

- The concentration of oxygen in the atmosphere Dion roughly similar to the one you can not find the some 500 miles above Earth - says Robert Turner, a researcher at Los Alamos National Laboratory.

- It is not enough to sustain life, but it is definitely an example of the process in which oxygen is formed on icy celestial bodies are bombarded with charged particles or photons from the sun or any light source which is near - he adds.

The researchers - who did not believe that either Dion large enough to support the exosphere - now dig through the data he collected, "Cassini" to find some more information to help them in search of wildlife outside of our "home" planet.

Some of them believe that the month is below the water surface, as is the case with Jupiter's satellite Europa, molecular oxygen is combined with carbon in the subsurface lakes could have blocks of living space: although researchers at the University of South Florida announced that the oceans are too Europium acid for that.

"Cassini" are now turning to another Saturn moon, Enkeladusu: one of the brightest objects in our solar system that reflects almost all light it receives, due to the surface of ice crystals. What will discover there, unfortunately we will learn only a few years.

Wednesday, 14 March 2012

Study raises questions over nano impact

Tests involving chickens have raised questions about the impact on health from engineered nano-particles, the ultra-fine grains commonly used in drugs and processed foods.

Chickens exposed to high oral doses of polystyrene particles 50 nanometres (50 billionths of a metre) across absorbed less iron in their diet, according to the new study.

At the same time, birds that were chronically exposed to these doses had a "remodelling" of their intestinal villi, the microscopic finger-like projections that play an important role in absorbing nutrients.

The changes meant that the villi increased the surface area available for taking in iron.

Intestinal uptake of calcium, copper, zinc and vitamins A, D, E and K may also be affected by high exposure to nanoparticles, although further research is needed to investigate this, say the authors.

The team, led by Michael Shuler of Cornell University in New York, tested the particles on chickens as a substitute for the human intestine and also used lab-dish cells from the lining of the human gut.

The chickens were given roughly the same dose, weight for weight, as an adult human in a developed country.

"The intestinal epithelial layer represents the initial gate that ingested nanoparticles must pass to reach the body," says the paper, which appears in the specialist journal Nature Nanotechnology.

"The polystyrene particles used in these experiments are generally considered non-toxic, but their interaction with a normal physiological process suggests a potential mechanism for a chronic, harmful, but subtle response."
Increasing usage

Engineered nanoparticles are used increasingly in the form of titanium oxide or as aluminium silicates in pills to help deliver medication and in food, where they are used as stabilisers or anti-caking agents in fluids and creams.

In developed countries, individuals may be consuming each day a thousand billion engineered particles ranging from fine to ultrafine in scale, according to figures from 2002 research quoted in the study.

Previous research has suggested micron- and nano-sized particles could play a role in the painful inflammatory gut disorder called Crohn's disease, says the paper.

Most of these particles have a negatively-charged surface, which means they adhere to biomolecules in the gut, accumulating at lymphoid nodules called Peyer's patches, according to the earlier research.

Monday, 12 March 2012

A MITOSIS MYSTERY SOLVED: How Chromosomes Align Perfectly in a Dividing Cell

To solve a mystery, sometimes a great detective need only study the clues in front of him. Like Agatha Christie's Hercule Poirot and Arthur Conan Doyle's Sherlock Holmes, Tomomi Kiyomitsu used his keen powers of observation to solve a puzzle that had mystified researchers for years: in a cell undergoing mitotic cell division, what internal signals cause its chromosomes to align on a center axis?

"People have been looking at these proteins and players in mitosis for decades, and no one ever saw what Tomomi observed," says Whitehead Institute Member Iain Cheeseman. "And it's very clear that these things are happening. These are very strong regulatory paradigms that are setting down these cell division axes. And careful cell biology allowed him to see that this was occurring. People have been looking at this for a long time, but never with the careful eyes he brought to it."

Kiyomitsu, a postdoctoral researcher in Cheeseman's lab, published his work in a recent issue of the journal Nature Cell Biology.

The process of mitotic cell division has been studied intensely for more than 50 years. Using fluorescence microscopy, today's scientists can see the tug-of-war cells undergo as they move through mitosis. Thread-like proteins, called microtubules, extend from one of two spindle poles on either side of the cell and attempt to latch onto the duplicated chromosomes. This entire "spindle" structure acts to physically distribute the chromosomes, but it is not free floating in the cell. In addition to microtubules from both spindle poles that attach to all of the chromosomes, astral microtubules that are connected to the cell cortex -- a protein layer lining the cell membrane -- act to pull the spindle poles back and forth within the cell until the spindle and chromosomes align down the center axis of the cell. Then the microtubules tear the duplicated chromosomes in half, so that ultimately one copy of each chromosome ends up in each of the new daughter cells.

The process of mitosis is extremely precise; when it comes to manipulating DNA, cells verge on being obsessive and with good reason. Gaining or losing a chromosome during cell division can lead to cell death, developmental disorders, or cancer.

As Kiyomitsu watched mitosis unfold in symmetrically dividing human cells, he noticed that when the spindle oscillates toward the cell's center, a partial halo of the protein dynein lines the cell cortex on the side farther away from the spindle. As the spindle swings to the left, dynein appears on the right, but when the spindle swing to the right, dynein vanishes and reappears on the left side.

For Kiyomitsu, the key to the alignment mystery was dynein, which is known as a motor protein that "walks" molecular cargoes along microtubules. Kiyomitsu determined that in this case, dynein is anchored to the cell cortex by a complex that includes the protein LGN, short for leucine-glycine-asparagine-enriched protein. Instead of moving along an astral microtubule, the stationary dynein acts as a winch to pull on the spindle pole, and the microtubules and chromosomes attached to it, toward the cell cortex.

Kiyomitsu found that when a spindle pole comes within close proximity to the cell cortex, a signal from a protein called Polo-like kinase 1 (Plk1) emanates from the spindle pole, knocking dynein off of LGN and the cell cortex, stopping the spindle pole's forward motion, and freeing dynein to move to the opposite side of the cell. These oscillations continue with decreasing amplitude until the spindle settles along the cell's center axis.

As he was deciphering dynein's role in spindle alignment, Kiyomitsu noticed that a layer of LGN extends all around the cell cortex, except in the areas that are closest to the chromosomes. As the chromosomes swing back and forth, the area cleared of LGN changes in response. Because dynein needs to anchor to LGN, this cleared area ensures that dynein can only attach and pull to the right and left of the aligning chromosomes, rather than from above and below.

After testing a couple of signaling molecules associated with chromosomes, Kiyomitsu determined that a signal from the chromosomes, involving the ras-related nuclear protein (Ran), blocks LGN, and therefore dynein, from attaching to the cell cortex closest to the chromosomes. Ran bound to guanosine-5'-triphosphate (Ran-GTP), which controls nuclear import in the interphase stage of mitosis, had previously been suggested to control spindle assembly during mitosis in germ cells, but roles for the Ran gradient in mitotic non-germ cells were unclear. Kiyomitsu's work suggests a key role for Ran in directing spindle orientation.

Kiyomitsu says the axis that the spindle poles travel along is crucial to cells.

"The spindle orientation is critical for maintaining the balance between stem cells and mature cells during development," he notes. "And if this orientation becomes dysregulated or misregulated, it is reported that this may contribute to causing cancer even if chromosomes are properly segregated."

Saturday, 10 March 2012

How the zebra got its stripes

Rudyard Kipling may have answered how the leopard got its spots and the camel its hump, but he never explained the zebra's stripes. A new study helps fill in the void, this time with actual data.

Casting aside a long list of possible explanations, the new research proposes that a zebra's bold pattern of black and white stripes reflects light in a way that helps the animals evade disease-infested flies.

Hungry flies might not be the only force that pushed zebras to develop stripes. But the findings might offer new strategies for defending animals, and even people, against some insects.

"We have been breeding animals based on meat or milk production, and we haven't paid much attention to their coat colorations or patterns," says Susanne Åkesson, an evolutionary ecologist at Lund University in Sweden. "Maybe it's something we need to consider. Maybe there's some trick we can learn from the zebra that could help."

Scientists have been speculating about the purpose of the zebra's stripes since the 1870s, when Charles Darwin criticised Alfred Russel Wallace's theory that the stripes provided camouflage in tall grass. Zebras prefer open savannahs, Darwin argued, where the grass is too short to make stripes useful hiding tools.

Since then, theories have invoked zebra-to-zebra recognition, defense against lions who can't pick out an individual zebra from amongst a mass of stripes, and thermoregulation - as the patterns of dark and light fur might cause air turbulence, helping cool the animals off.

Åkesson and colleagues wondered if horseflies, which belong to a group called tabanids, might have something to do with the story. These flies are major pests for zebras, cows, horses and related animals. Their bites can be irritating enough to reduce grazing. And they can carry deadly diseases.
Animal attraction

In previous work, Åkesson and her team had found that horseflies are more attracted to dark animals than to white ones, likely because of the way that light reflects off of different surfaces. Direct sunlight is full of rays that shine in all directions. But when sunlight bounces off of water - or off of a dark brown horse or cow - its reflections align horizontally.

Tabanid flies are attracted to this kind of linearly polarised light: It often leads them to water, where they can lay their eggs and mate. Just as often, though, their polarised light sense leads them to large animals, which they bite and annoy to no end.

Since zebras are both dark and light, the researchers wondered if these striking animals might have an intermediate-level of attractiveness to flies. To find out, they conducted a series of experiments with oil-filled trays, odourless insect tape-covered panels and zebra-like plastic models that where black or brown, white or striped.

Every day for a few weeks during the summer on a Hungarian horse farm, flies flew to their preferred colour patterns and got trapped, allowing the researchers to collect the insects, count them and gauge their preferences.

As expected, very few flies landed on the white surfaces, the researchers report in the Journal of Experimental Biology, while hundreds went for the black objects in some cases. Surprisingly, the striped objects attracted just as few, and sometimes fewer, flies than the white surfaces did. More flies landed on black stripes than on white stripes.

When the researchers made the black stripes wider than a typical zebra's pattern, it attracted more flies. Measurements confirmed that the most polarised surfaces attracted the most insects.

Given the major advantage that zebras would get by avoiding fly bites that could kill them before they reproduced, says Åkesson, the paper offers a strong argument that stripes developed to protect the animals against insects and their diseases.
More to the story?

As solid as the new data is, though, the story is far from over, says Tim Caro, a behavioural ecologist at the University of California, Davis, who is writing a book about the evolution of the zebra's looks.

If stripes are so helpful, for example, why aren't all Eurasian horses striped? Meanwhile, studies have yet to carefully examine most of the other theories about zebra evolution. There might be many reasons why they are black and white.

Animal coloration has a long history of inspiring applications in military and other situations, Caro said, pointing to the black-and-white geometric patterns that decorated navy ships with "dazzle camouflage" during World War I.

Still, studies like this one may have their biggest impact on young minds, sparking excitement about science and the natural world.

"I think there's a real hidden and indirect conservation benefit to this kind of research," Caro says. "As we become increasingly urbanised and computer-focused rather than taking walks in the woods on Sunday afternoons, I think these handles whereby you can capture children's imaginations are going to be increasingly important."

Thursday, 8 March 2012

Accounting for missing particles

Measurements from high-energy collision experiments have led to a better understanding of why meson particles disappear.

For several years, physicists at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL), USA, have studied an unusual state of matter called the quark-gluon plasma, which they believe mimics the hot, dense particle soup that existed immediately after the big bang. Now, the PHENIX collaboration at RHIC reports findings about a particle called the J/ψ meson that will help physicists distinguish the properties of the quark-gluon plasma (QGP) from those of normal matter.

To create a QGP, physicists crash gold nuclei together at close to the speed of light. This provides enough energy to break apart the protons and neutrons in the nuclei into their constituent quarks and gluons, which mediate the force between quarks. In this energetic mash up, a host of short-lived particles can form, including mesons, which are made up of a quark and an anti-quark.

When collisions of gold nuclei yield fewer J/ψ mesons than expected from theoretical predictions, it indicates that a QGP has formed. Suppressed meson production can occur because the QGP weakens the binding force between the two quarks in the J/ψ particle. The PHENIX collaboration's detector counts the number of J/ψ mesons created in collisions by detecting the electrons and muons -- particles with the same charge, but more mass, than electrons -- produced from J/ψ decays.

Effects other than the formation of the QGP, however, can also suppress the yield of J/ψ particles, which makes interpreting gold-gold collisions "ambiguous," says Yasuyuki Akiba, a scientist at the RIKEN BNL Research Center and a member of the PHENIX collaboration.

To isolate these other effects, the PHENIX team analyzed data taken in 2003 and 2008 from collisions between deuterium -- a proton and neutron -- and gold, since these collisions cannot form a QGP. Even in the absence of a QGP, the team found the production of J/ψ particles was more suppressed than expected at the highest relative velocities between the deuterium and the gold collisions. "Conventional models cannot describe the data," says Akiba.

The team thinks the unexplained suppression may be related to how the apparent density of gluons in the gold nuclei, which determines the rate of J/ψ production, varies with the speed of the deuterium.

More analysis is needed to determine whether this explanation is correct, but this work "gives a precise baseline that will be very useful for separating the quark-gluon plasma effects in gold-gold collisions," says Akiba.

Tuesday, 6 March 2012

Electrical engineers build "no-waste" laser

A team of University of California, San Diego researchers has built the smallest room-temperature nanolaser to date, as well as an even more startling device: a highly efficient, "thresholdless" laser that funnels all its photons into lasing, without any waste.

The two new lasers require very low power to operate, an important breakthrough since lasers usually require greater and greater "pump power" to begin lasing as they shrink to nano sizes. The small size and extremely low power of these nanolasers could make them very useful components for future optical circuits packed on to tiny computer chips, Mercedeh Khajavikhan and her UC San Diego Jacobs School of Engineering colleagues report in the Feb. 9 issue of the journal Nature.

They suggest that the thresholdless laser may also help researchers as they develop new metamaterials, artificially structured materials that are already being studied for applications from super-lenses that can be used to see individual viruses or DNA molecules to "cloaking" devices that bend light around an object to make it appear invisible.

All lasers require a certain amount of "pump power" from an outside source to begin emitting a coherent beam of light or "lasing," explained Yeshaiahu (Shaya) Fainman, a professor in the Department of Electrical and Computer Engineering at UC San Diego and co-author of the new study. A laser's threshold is the point where this coherent output is greater than any spontaneous emission produced.

The smaller a laser is, the greater the pump power needed to reach the point of lasing. To overcome this problem, the UC San Diego researchers developed a design for the new lasers that uses quantum electrodynamic effects in coaxial nanocavities to alleviate the threshold constraint. Like a coaxial cable hooked up to a television (only at a much smaller scale), the laser cavity consists of a metal rod enclosed by a ring of metal-coated, quantum wells of semiconductor material. Khajavikhan and the rest of the team built the thresholdless laser by modifying the geometry of this cavity.

The new design also allowed them to build the smallest room-temperature, continuous wave laser to date. The new room-temperature nanoscale coaxial laser is more than an order of magnitude smaller than their previous record smallest nanolaser published in Nature Photonics less than two years ago. The whole device is almost half a micron in diameter -- by comparison, the period at the end of this sentence is nearly 600 microns wide.

These highly efficient lasers would be useful in augmenting future computing chips with optical communications, where the lasers are used to establish communication links between distant points on the chip. Only a small amount of pump power would be required to reach lasing, reducing the number of photons needed to transmit information, said Fainman.

The nanolaser designs appear to be scalable -- meaning that they could be shrunk to even smaller sizes -- an extremely important feature that makes it possible to harvest laser light from even smaller nanoscale structures, the researchers note. This feature eventually could make them useful for creating and analyzing metamaterials with structures smaller than the wavelength of light currently emitted by the lasers.

Fainman said other applications for the new lasers could include tiny biochemical sensors or high-resolution displays, but the researchers are still working out the theory behind how these tiny lasers operate. They would also like to find a way to pump the lasers electrically instead of optically.

Sunday, 4 March 2012

Earth is getting lighter every day

Earth is getting 50,000 tonnes lighter every year, even while 40,000 tonnes of space dust fall on our planet's surface during the same period. So, why are we losing so much weight? You will be surprised.

At least, I never considered this and I was surprised to hear the reasoning in More or Less, a BBC Radio 4 program about statistics and numbers. According to Dr Chris Smith and Cambridge University physicist Dave Ansel's calculations, despite those 40,000 tonnes of space dust that become part of our planet every year, Earth loses 50,000 tonnes of mass. Is it because we keep launching rockets? No. These are their back-of-the-napkin calculations:
Adding weight

• Earth gains about 40,000 tonnes of dust every year, the remnants of the formation of the solar system, which are attracted by our gravity and become part of the matter in our planet. Our planet is actually made from all that starstuff.
• NASA says that Earth gains about 160 tonnes of matter a year because the global temperature is going up: "If we are adding energy to the system, the mass must go up." Oh, those crazy thermodynamics.
No effect

• Of course, having more people or building stuff doesn't add any mass to the planet. Humans and things are made with the matter that is already in the planet. It's just being transformed.
• Most of the rockets and satellites that we launch to Earth orbit eventually fall down back to Earth, so no real effect here.
Losing weight

• Earth's core loses energy over time. It's like a giant nuclear reactor that burns fuel. Less energy means less mass. 16 tonnes of that are gone every year. Not much.
• And here's the big mass loss: about 95,000 tonnes of hydrogen and 1,600 tones of helium escape Earth every year. They are too light for gravity to keep them around, so they get lost. Gone into space.

The result: the rough estimate is -50,000 tonnes every year. Which is about 0.000000000000001% less mass every year.

Should we be worried about Earth disappearing into thin air? No, you shouldn't. And you shouldn't worry about losing hydrogen. There's plenty and it will take trillions of years to deplete it.

Helium, on the other hand, is a different matter. It represents 0.00052% of the volume in our atmosphere, but it's mainly harvested from natural gas using a process called fractional distillation. Helium is becoming scarce in our planet. In fact, Cornell University physicist and Nobel Prize-winner Robert Richardson once said that each floating party balloon should have a $100 price tag, who campaigned against the US Government decision to sell the country's helium stockpile by 2015 to keep prices down.

He's probably right, considering that it is crucial for devices like MRI scanners, where it is used for cooling superconducting magnets and growing silicon and germanium crystals as well as the production of titanium and zirconium.

Friday, 2 March 2012

Engineers weld nanowires with light

At the nano level, researchers at Stanford have discovered a new way to weld together meshes of tiny wires. Their work could lead to innovative electronics and solar applications. To succeed, they called upon plasmonics.

One area of intensive research at the nanoscale is the creation of electrically conductive meshes made of metal nanowires. Promising exceptional electrical throughput, low cost and easy processing, engineers foresee a day when such meshes are common in new generations of touch-screens, video displays, light-emitting diodes and thin-film solar cells.

Standing in the way, however, is a major engineering hurdle: In processing, these delicate meshes must be heated or pressed to unite the crisscross pattern of nanowires that form the mesh, damaging them in the process.

In a paper just published in the journal Nature Materials, a team of engineers at Stanford has demonstrated a promising new nanowire welding technique that harnesses plasmonics to fuse the wires with a simple blast of light.


At the heart of the technique is the physics of plasmonics, the interaction of light and metal in which the light flows across the surface of the metal in waves, like water on the beach.

"When two nanowires lay crisscrossed, we know that light will generate plasmon waves at the place where the two nanowires meet, creating a hot spot. The beauty is that the hot spots exist only when the nanowires touch, not after they have fused. The welding stops itself. It's self-limiting," explained Mark Brongersma, an associate professor of materials science engineering at Stanford and an expert in plasmonics. Brongersma is one of the study's senior authors.

"The rest of the wires and, just as importantly, the underlying material are unaffected," noted Michael McGehee, a materials engineer and also senior author of the paper. "This ability to heat with precision greatly increases the control, speed and energy efficiency of nanoscale welding."

In before-and-after electron-microscope images, individual nanowires are visually distinct prior to illumination. They lay atop one another, like fallen trees in the forest. When illuminated, the top nanowire acts like an antenna of sorts, directing the plasmon waves of light into the bottom wire and creating heat that welds the wires together. Post-illumination images show X-like nanowires lying flat against the substrate with fused joints.


In addition to making it easier to produce stronger and better performing nanowire meshes, the researchers say that the new technique could open the possibility of mesh electrodes bound to flexible or transparent plastics and polymers.

To demonstrate the possibilities, they applied their mesh on Saran wrap. They sprayed a solution containing silver nanowires in suspension on the plastic and dried it. After illumination, what was left was an ultrathin layer of welded nanowires.

"Then we balled it up like a piece of paper. When we unfurled the wrap, it maintained its electrical properties," said co-author Yi Cui, an associate professor materials science and engineering. "And when you hold it up, it's virtually transparent."

This could lead to inexpensive window coatings that generate solar power while reducing glare for those inside, the researchers said.

"In previous welding techniques that used a hotplate, this would never have been possible," said lead author, Erik C. Garnett, PhD, a post-doctoral scholar in materials science who works with Brongersma, McGehee and Cui. "The Saran wrap would have melted far sooner than the silver, destroying the device instantly."

"There are many possible applications that would not even be possible in older annealing techniques," said Brongersma. "This opens some interesting, simple and large-area processing schemes for electronic devices -- solar, LEDs and touch-screen displays, especially."