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Mystery of how homing pigeons find home solved

Mystery of how homing pigeons find home solved | Amazing Science | Scoop.it
The mystery of how homing pigeons are able to navigate home may have been solved. The birds use low-frequency sound waves to make a mental map of their location, new research suggests.

 

In 1969, a Cornell biology professor gave a talk to geologists at the school about the mystery of the lost homing pigeons. If the pigeons were taken to almost any locations, they headed straight home with amazing accuracy. But at one location, called Jersey Hill, the pigeons got completely lost, with each taking off in a random direction. At two other locations, the birds consistently headed in the same wrong direction. On a few trips, the birds would miraculously make it home, but then get lost the next day.


United States Geological Survey geologist John Hagstrum heard the talk, and the question nagged at him for years. In the 1990s, he discovered that birds in European pigeon races were going astray on clear-weather days, when the Concord, the supersonic plane, was in the area. That led him to wonder whether the sonic boom from the Concorde plane disrupted pigeon navigation by interfering with the sound waves.


Prior research had shown that birds hear incredibly low-frequency sound waves of about 0.1 Hertz, or a tenth of a cycle per second. These infrasound waves may emanate from in the ocean and create tiny disturbances in the atmosphere. Hagstrum began to think the birds used infrasound for navigation. To test the idea that pigeons use infrasound to make an acoustic map of home, he used a computer program to model the emanation of infrasound waves from 200 sites around Cornell University where about 45,000 pigeons had been released over a 14-year period. He then compared sound wave location data with information on whether the pigeons had made it home.


Hagstrum found that on the days when the pigeons got lost, the infrasound waves from Jersey Hill didn't reach their home loft at Cornell. Even more interesting, on the odd day when the birds reached home from Jersey Hill without problems, the infrasound traveled between the two locations. At the other locations where pigeons headed off in the wrong direction, he showed that wind currents channeled the infrasound waves in that direction.

 

The explanation may solve other mysteries about pigeons — for instance, why they circle around before heading off in one direction. Because the sound waves are so long, but the birds' ear canals are tiny, they need to circle to reconstruct the wave and figure out which way they are oriented, he said.


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150 kilowatt lasers will be installed in US Fighter planes as early as 2014

150 kilowatt lasers will be installed in US Fighter planes as early as 2014 | Amazing Science | Scoop.it

The goal of the High Energy Liquid Laser Area Defense System (HELLADS) program is to develop a high-energy laser weapon system (150 kW) with an order of magnitude reduction in weight compared to existing laser systems. With a weight goal of less than 5 kg/kW, HELLADS will enable high energy lasers (HELs) to be integrated onto tactical aircraft, and will significantly increase engagement ranges compared to ground-based systems, enabling high precision, low collateral damage, and rapid engagement of fleeting targets for both offensive and defensive missions. The HELLADS program has completed the design and demonstration of a revolutionary prototype unit cell laser module. That unit cell demonstrated power output and is demonstrating optical wavefront performance that supports the goal of a lightweight and compact 150 kW high energy tactical laser weapon system. Two unit cell module designs with integrated power and thermal management systems were fabricated and tested; they demonstrated an output power exceeding 34 kW. Based on the results of the unit cell demonstration, additional laser modules will be replicated and connected to produce a 150 kW laser that will be demonstrated in a laboratory environment. The 150 kW laser will then be integrated with beam control, prime power, thermal management, safety, and command and control subsystems all based upon existing technologies to produce a ground-based laser weapon system field demonstrator. The capability to shoot down tactical targets such as surface-to-air missiles and rockets and the capability to perform ultra-precise offensive engagements will be demonstrated in a realistic ground test environment. Additional funding for this integration effort will be provided for HELLADS testing in Project NET-01, PE 0603766E starting in FY 2011. The HELLADS laser will then be transitioned to the Air Force for modification and aircraft integration and flight testing.

 

http://www.ga-asi.com/news_events/index.php?read=1&id=366

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Engineered immune cells strongly resist HIV infection

Engineered immune cells strongly resist HIV infection | Amazing Science | Scoop.it

One of the big challenges in treating AIDS is that the virus is notorious for mutating, so patients must be treated with a cocktail of drugs — known as highly active antiretroviral therapy or HAART — which hit it at various stages of the replication process. The researchers were able to get around that problem with a new, multi-pronged genetic attack that blocks HIV on several fronts. Essentially, they hope to mimic HAART through genetic manipulation.

The technique hinges on the fact that the virus typically enters T cells by latching onto one of two surface proteins known as CCR5 and CXCR4.

 

Some of the latest drugs now used in treatment work by interfering with these receptors’ activity. A small number of people carry a mutation in CCR5 that makes them naturally resistant to HIV. One AIDS patient with leukemia, now famously known as the Berlin patient, was cured of HIV when he received a bone marrow transplant from a donor who had the resistant CCR5 gene.

 

Scientists at Sangamo BioSciences in Richmond, Calif., have developed a technique using a protein that recognizes and binds to the CCR5 receptor gene, genetically modifying it to mimic the naturally resistant version. The technique uses a zinc finger nuclease, a protein that can break up pieces of DNA, to effectively inactivate the receptor gene. The company is now testing its CCR5-resistant genes in phase-1 and -2 trials with AIDS patients at the University of Pennsylvania.

 

The Stanford scientists used a similar approach but with an added twist. They used the same nuclease to zero in on an undamaged section of the CCR5 receptor’s DNA. They created a break in the sequence and, in a feat of genetic editing, pasted in three genes known to confer resistance to HIV, Porteus said. This technique of placing several useful genes at a particular site is known as “stacking.”

 

Incorporating the three resistant genes helped shield the cells from HIV entry via both the CCR5 and CXCR4 receptors. The disabling of the CCR5 gene by the nuclease, as well as the addition of the anti-HIV genes, created multiple layers of protection.

 

Blocking HIV infection through both the CCR5 and CXCR4 receptors is important, Porteus said, as it hasn’t been achieved before by genome editing. To test the T cells’ protective abilities, the scientists created versions in which they inserted one, two and all three of the genes and then exposed the T cells to HIV.

 

Though the T cells with the single- and double-gene modifications were somewhat protected against an onslaught of HIV, the triplets were by far the most resistant to infection. These triplet cells had more than 1,200-fold protection against HIV carrying the CCR5 receptor and more than 1,700-fold protection against those with the CXCR4 receptor, the researchers reported. The T cells that hadn’t been altered succumbed to infection with 25 days.

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Aging cells lose their grip on controling transposable elements

Aging cells lose their grip on controling transposable elements | Amazing Science | Scoop.it

 

Transposable elements are mobile strands of DNA that insert themselves into chromosomes with mostly harmful consequences. Cells try to keep them locked down, but in a new study, Brown University researchers report that aging cells lose their ability to maintain this control. The result may be a further decline in the health of senescent cells and of the aging bodies they compose.

Even in our DNA there is no refuge from rogues that prey on the elderly. Parasitic strands of genetic material called transposable elements—transposons—lurk in our chromosomes, poised to wreak genomic havoc. Cells have evolved ways to defend themselves, but in a new study, Brown University researchers describe how cells lose this ability as they age, possibly resulting in a decline in their function and health. Barbara McClintock, awarded the Nobel Prize in 1983, made the original discovery of transposons in maize. Since then scientists have found cases in which the chaos they bring can have long-term benefits by increasing genetic diversity in organisms, but in most cases the chaos degrades cell function, such as by disrupting useful genes. "The cell really is trying to keep these things quiet and keep these things repressed in its genome," said John Sedivy, professor of medical science in the Department of Molecular Biology, Cell Biology, and Biochemistry and senior author of the new study published online in the journal Aging Cell. "We seem to be barely winning this high-stakes warfare, given that these molecular parasites make up over 40 percent of our genomes." Cells try to clamp down on transposons by winding and packing transposon-rich regions of the genome around little balls of protein called nucleosomes. This confining arrangement is called heterochromatin, and the DNA that is trapped in such a tight heterochromatin prison cannot be transcribed and expressed. What the research revealed, however, is that carefully maintaining a heterochromatin prison system is a younger cell's game.

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RNA Fragments in Exosomes May Yield Rapid, Accurate Cancer Diagnosis

RNA Fragments in Exosomes May Yield Rapid, Accurate Cancer Diagnosis | Amazing Science | Scoop.it

A new method to noninvasively diagnose cancer and monitor its progression could eliminate the need for painful and sometimes life-threatening biopsies. Fragments of RNA that cells eject in fatty droplets may point the way to a new era of cancer diagnosis, potentially eliminating the need for invasive tests in certain cases.

 

Cancer tumor cells shed microvesicles containing proteins and RNA fragments, called exosomes, into cerebral spinal fluid, blood, and urine. Within these exosomes is genetic information that can be analyzed to determine the cancer’s molecular composition and state of progression. Researchers at Massachusetts General Hospital discovered that exosomes preserve the genetic information of their parent cells in 2008, however exosomes have not seen widespread clinical testing as a means of cancer diagnosis until now.

 

“We have never really been able to detect the genetic components of a tumor by blood or spinal fluid,” says Harvard University neurologist Fred Hochberg. “This is really a new strategy.” He says exosome diagnostic tests could potentially detect and monitor the progression of a wide variety of cancers. He is one of the lead researchers in a multicenter clinical study using new exosomal diagnostic tests developed by New York City-based Exosome Diagnostics to identify a genetic mutation found exclusively in glioma, the most common form of brain cancer.

 

When treating other forms of cancer, surgeons are able to biopsy tumors to diagnose and monitor the state of the disease. For brain cancers like glioma, however, multiple biopsies can be life threatening. Bob Carter, head of neurosurgery at the University of California, San Diego, says well-preserved RNA in blood and spinal fluid enables researchers to test and monitor for these genetic changes noninvasively.

 

He says study researchers separate exosomes from bio-fluids with a diagnostic kit and then extract the relevant genomic information. Once the specific cancer mutation is identified, clinicians will periodically draw additional bio-fluids to monitor the mutation levels to determine whether a patient is responding to therapy.  

 

Whereas Magnetic Resonance Imaging (MRI) is a useful tool, tumors only show up on imaging scans once they are at least one millimeter in diameter and comprise about 100,000 tumor cells. By that time, it may be too late for an early intervention. On the flip side, MRIs can also yield false positives. Hochberg says individuals who have been treated with conventional radiation therapy often have benign residual tissue from dying tumor cells that have been killed by the treatment but which the body has not yet eliminated. This tissue is often mistaken for tumor growth on a MRI scan. “You would identify to the patient that the drug is not working when in reality it is doing well,” Hochberg says. “On the other hand, having an easily accessible biomarker for glioma would give you a clear response.”

 

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DARPA shows off 1.8-gigapixel surveillance drone that can spot a terrorist from 20,000 feet above

DARPA shows off 1.8-gigapixel surveillance drone that can spot a terrorist from 20,000 feet above | Amazing Science | Scoop.it

DARPA and the US Army have taken the wraps off ARGUS-IS, a 1.8-gigapixel video surveillance platform that can resolve details as small as six inches from an altitude of 20,000 feet (6km). ARGUS is by far the highest-resolution surveillance platform in the world, and probably the highest-resolution camera in the world, period.

 

ARGUS, which would be attached to some kind of unmanned UAV (such as the Predator) and flown at an altitude of around 20,000 feet, can observe an area of 25 square kilometers (10sqmi) at any one time. If ARGUS was hovering over New York City, it could observe half of Manhattan. Two ARGUS-equipped drones, and the US could keep an eye on the entirety of Manhattan, 24/7.

 

It is the definition of “observe” in this case that will blow your mind, though. With an imaging unit that totals 1.8 billion pixels, ARGUS captures video (12 fps) that is detailed enough to pick out birds flying through the sky, or a lost toddler wandering around. These 1.8 gigapixels are provided via 368 smaller sensors, which DARPA/BAE says are just 5-megapixel smartphone camera sensors. These 368 sensors are focused on the ground via four image-stabilized telescopic lenses.

 

ARGUS’s insane resolution is only half of the story, though. It isn’t all that hard to strap a bunch of sensors together, after all. The hard bit, according to the Lawrence Livermore National Laboratory (LLNL), is the processing of all that image data. 1.8 billion pixels, at 12 fps, generates on the order of 600 gigabits per second. This equates to around 6 petabytes — or 6,000 terabytes — of video data per day. From what we can gather, some of the processing is done within ARGUS (or the drone that carries it), but most of the processing is done on the ground, in near-real-time, using a beefy supercomputer. We’re not entirely sure how such massive amounts of data are transmitted wirelessly, unless DARPA is waiting for its 100Gbps wireless tech to come to fruition.

 

The software, called Persistics after the concept of persistent ISR — intelligence, surveillance, and reconnaissance — is tasked with identifying objects on the ground, and then tracking them indefinitely. As you can see in the video, Persistics draws a colored box around humans, cars, and other objects of interest. These objects are then tracked by the software — and as you can imagine, tracking thousands of moving objects across a 10-square-mile zone is a fairly intensive task. The end user can view up to 65 tracking windows at one time.

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Simulating 25,000 generations of evolution, researchers discover why biological networks tend to organize

Simulating 25,000 generations of evolution, researchers discover why biological networks tend to organize | Amazing Science | Scoop.it

By simulating 25,000 generations of evolution within computers, Cornell University engineering and robotics researchers have discovered why biological networks tend to be organized as modules – a finding that will lead to a deeper understanding of the evolution of complexity. The new insight also will help evolve artificial intelligence, so robot brains can acquire the grace and cunning of animals. From brains to gene regulatory networks, many biological entities are organized into modules – dense clusters of interconnected parts within a complex network.


For decades biologists have wanted to know why humans, bacteria and other organisms evolved in a modular fashion. Like engineers, nature builds things modularly by building and combining distinct parts, but that does not explain how such modularity evolved in the first place. Renowned biologists Richard Dawkins, Günter P. Wagner, and the late Stephen Jay Gould identified the question of modularity as central to the debate over "the evolution of complexity." For years, the prevailing assumption was simply that modules evolved because entities that were modular could respond to change more quickly, and therefore had an adaptive advantage over their non-modular competitors. But that may not be enough to explain the origin of the phenomena. The team discovered that evolution produces modules not because they produce more adaptable designs, but because modular designs have fewer and shorter network connections, which are costly to build and maintain. As it turned out, it was enough to include a "cost of wiring" to make evolution favor modular architectures.

The results may help explain the near-universal presence of modularity in biological networks as diverse as neural networks – such as animal brains – and vascular networks, gene regulatory networks, protein-protein interaction networks, metabolic networks and even human-constructed networks such as the Internet. "Being able to evolve modularity will let us create more complex, sophisticated computational brains," says Clune. Says Lipson: "We've had various attempts to try to crack the modularity question in lots of different ways. This one by far is the simplest and most elegant."

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Corning Invents a Thin, Flexible Glass that Can be Mass-Produced

Corning Invents a Thin, Flexible Glass that Can be Mass-Produced | Amazing Science | Scoop.it

In 2011, a Corning researcher named Terry Ott faced a problem that nobody else had needed to solve in the company’s 160-year history: how to make sheets of glass that could be rolled onto spools.

 

The challenge arose because Corning had developed a new kind of glass, known as Willow, which is as thin as a sheet of paper and acts a bit like it, too—if you shake it, it will rattle, and it can bend enough to be spooled. It could be the basis for displays in thinner, lighter cell phones and tablets—or for entirely new products, like displays that fit the curve of your wrist.

 

Inventing the glass was an achievement in itself for Corning, which also makes the durable Gorilla Glass used in Apple’s iPhone and other mobile devices. But Willow, which is one-third as thick as Gorilla Glass, would be a meaningless breakthrough if Corning couldn’t figure out how to make it in large quantities—and in a way that customers could use on their own production lines. The way Corning solved the problem of mass-producing Willow helps illustrate the extent to which technological innovation depends on close connections between R&D and manufacturing.

 

Some of the work was straightforward: Willow is made with Corning’s core manufacturing technology, a process called fusion forming, which involves heating glass in a trough. At the right temperature, the molten glass will evenly pour over the sides and then solidify at the bottom, where it can be drawn downward into a vertical sheet and then cut.

 

But to get Willow made in continuous sheets, Ott’s team had to figure out the proper rate at which to draw the glass out after it fused, so that the surface quality would be consistent. The process of getting the glass onto rollers also required new equipment. And Ott’s team had to develop thin plastic tabs to line the edges of the glass and keep it from touching anything on the rollers, which could create defects in its surface. The tabs are applied to Willow’s edges as the glass is being drawn.

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Of Einstein and entanglement: Quantum erasure deconstructs wave-particle duality

Of Einstein and entanglement: Quantum erasure deconstructs wave-particle duality | Amazing Science | Scoop.it

Quantum physics presents several counterintuitive features, including entanglement, tunneling and – as demonstrated in double-slit experiments – wave-particle duality. When studying wave-particle duality, however, so-called interferometric quantum eraser experiments – in which wave-like behavior can be restored by erasing path information – allow researchers to perform differential measurements on each of two entangled quantum systems. (Double-slit experiments not involving quantum erasure utilize superposition of single particles, while in quantum eraser experiments two particles are entangled.) Specifically, the particle feature's welcher-weg (which-path) information is erased (or not) from one system, and interference-based measurements in the other system are used to observe (or not, as the case may be) its wave feature.

Figure: (A) Scheme of the Vienna experiment: In Lab 1, the source (S) emits polarization entangled photon pairs, each consisting of a system and an environment photon, via type-II spontaneous parametric down-conversion. Good spectral and spatial mode overlap is achieved by using interference filters with1-nm bandwidth and by collecting the photons into single-mode fibers. The polarization entangled state is subsequently converted into a hybrid entangled state with a polarizing beam splitter (PBS1) and two fiber polarization controllers (FPC). Interferometric measurement of the system photon is performed with a single-mode fiber beam splitter (BS) with a path length of 2 m, where the relative phase between path a and path b is adjusted by moving PBS1’s position with a piezo-nanopositioner. The polarization projection setup of the environment photon consists of an electro-optic modulator (EOM) and another PBS (PBS2). Both photons are detected by silicon avalanche photodiodes (DET 1–4). The choice is made with a QRNG (44). (B) Space–time diagram. The choice-related events Ce and the polarization projection of the environment photon Pe are space-like separated from all events of the interferometric measurement of the system photon Is. Additionally, the events Ce are also space-like separated from the emission of the entangled photon pair from the source Ese. Shaded areas are the past and the future light cones of events Is. This ensures that Einstein locality is fulfilled. BS, beam splitter; FPCs, fiber polarization controllers; PBS, polarized beam splitter.

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Gigantic loop of Black Holes and Neutron Stars raising through their evolution in a few million years or less

Gigantic loop of Black Holes and Neutron Stars raising through their evolution in a few million years or less | Amazing Science | Scoop.it

Arp 147 contains the remnant of a spiral galaxy (right) that collided with the elliptical galaxy on the left. This collision has produced an expanding wave of star formation that shows up as a blue ring containing in abundance of massive young stars. These stars race through their evolution in a few million years or less and explode as supernovas, leaving behind neutron stars and black holes. A fraction of the neutron stars and black holes will have companion stars, and may become bright X-ray sources as they pull in matter from their companions. The nine X-ray sources scattered around the ring in Arp 147 are so bright that they must be black holes, with masses that are likely ten to twenty times that of the Sun.


 An X-ray source is also detected in the nucleus of the red galaxy on the left and may be powered by a poorly-fed supermassive black hole. This source is not obvious in the composite image but can easily be seen in the X-ray image. Other objects unrelated to Arp 147 are also visible: a foreground star in the lower left of the image and a background quasar as the pink source above and to the left of the red galaxy. 

Infrared observations with NASA's Spitzer Space Telescope and ultraviolet observations with NASA's Galaxy Evolution Explorer (GALEX) have allowed estimates of the rate of star formation in the ring. These estimates, combined with the use of models for the evolution of binary stars have allowed the authors to conclude that the most intense star formation may have ended some 15 million years ago, in Earth's time frame.

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Assembly of a three-dimensional multitype tissue structures using magnetic levitation

Assembly of a three-dimensional multitype tissue structures using magnetic levitation | Amazing Science | Scoop.it

A longstanding goal in biomedical research has been to create organotypic co-cultures that faithfully represent native tissue environments. There is presently great interest in representative culture models of the lung, which is a particularly challenging tissue to recreate in vitro. This study used magnetic levitation in conjunction with magnetic nanoparticles as a means of creating an organized 3D co-culture of the bronchiole that sequentially layers cells in a manner similar to native tissue architecture. The 3D co-culture model was assembled from four human cell types in the bronchiole: endothelial cells, smooth muscle cells, fibroblasts, and epithelial cells. This study represents the first effort to combine these particular cell types into an organized bronchiole co-culture. These cell layers were first cultured in 3D by magnetic levitation and then manipulated into contact with a custom-made magnetic pen, and again cultured for 48 h. Hematoxylin & eosin staining of the resulting co-culture showed four distinct layers within the 3D co-culture.

 

Immunohistochemistry confirmed the phenotype of each of the four cell types, and showed organized extracellular matrix formation, particularly with collagen type I. Positive stains for CD31, von Willebrand factor, smooth muscle α-actin, vimentin, and fibronectin demonstrate the maintenance of phenotype for endothelial cells, smooth muscle cells, and fibroblasts. Positive stains for mucin-5AC, cytokeratin, and E-cadherin after 7 days with and without 1% FBS showed that epithelial cells maintained phenotype and function. This study validates magnetic levitation as a method for the rapid creation of organized 3D co-cultures that maintain phenotype and induce extracellular matrix formation.

 

See also Nano3D: http://tinyurl.com/afttky3

 

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Norwegians trap sunlight with microbeads, produce solar cells that are 20 times thinner, cheaper

Norwegians trap sunlight with microbeads, produce solar cells that are 20 times thinner, cheaper | Amazing Science | Scoop.it

Researchers from the University of Oslo have used a bunch of “wonderful tricks” to produce silicon solar cells that are twenty times thinner than commercial solar cells. This breakthrough means that solar cells can be produced using 95% less silicon, reducing production costs considerably — both increasing profits (which are almost nonexistent at the moment), and reducing the cost of solar power installations.

 

Standard, commercial photovoltaic solar cells are fashioned out of 200-micrometer-thick (0.2mm) wafers of silicon, which are sliced from a large block of silicon. This equates to around five grams of silicon per watt of solar power, and also a lot of wastage — roughly half of the silicon block is turned into sawdust by the slicing process. With solar cells approaching 50 cents per watt (down from a few dollars per watt a few years ago), something needs to change.

 

Reducing the thickness of solar cells obviously makes a lot of sense from a commercial point of view, but it introduces another issue: As the wafer gets thinner, more light passes straight through the silicon, dramatically reducing the amount of electricity produced by the photovoltaic effect. This is due to wavelengths: Blue light, which has a short wavelength (450nm), can be captured by a very thin wafer of silicon — but red light, with a longer wavelength (750nm), can only be captured by thicker slabs of silicon. This is part of the reason that current solar cells use silicon wafers that are around 200 micrometers — and also why they’re mirrored, which doubles the effective thickness, allowing them to capture more of the visible spectrum.

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Bioinspired fibers change color when stretched

Bioinspired fibers change color when stretched | Amazing Science | Scoop.it

Color-tunable photonic fibers mimic the fruit of the “bastard hogberry” plant.

 

Since the evolution of the first eye on Earth more than 500 million years ago, the success of many organisms has relied upon the way they interact with light and color, making them useful models for the creation of new materials. For seeds and fruit in particular, bright color is thought to have evolved to attract the agents of seed dispersal, especially birds.

 

The fruit of the South American tropical plant, Margaritaria nobilis, commonly called “bastard hogberry,” is an intriguing example of this adaptation. The ultra-bright blue fruit, which is low in nutritious content, mimics a more fleshy and nutritious competitor. Deceived birds eat the fruit and ultimately release its seeds over a wide geographic area.

 

A team of materials scientists at Harvard University and the University of Exeter, UK, have invented a new fiber that changes color when stretched. Inspired by nature, the researchers identified and replicated the unique structural elements that create the bright iridescent blue color of a tropical plant’s fruit.

 

The multilayered fiber, described today in the journal Advanced Materials, could lend itself to the creation of smart fabrics that visibly react to heat or pressure.

 

“Our new fiber is based on a structure we found in nature, and through clever engineering we’ve taken its capabilities a step further,” says lead author Mathias Kolle, a postdoctoral fellow at the Harvard School of Engineering and Applied Sciences (SEAS). “The plant, of course, cannot change color. By combining its structure with an elastic material, however, we’ve created an artificial version that passes through a full rainbow of colors as it’s stretched.”

 

The photonic fibers are made by wrapping multiple layers of polymer around a glass core, which is later etched away. The thickness of the layers determines the apparent color of the fiber, which can range across the entire visible spectrum of light (see image).

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Julien : Possibilité de modificaition de la couleur de fibres en fonction de la déformation ou de la température

Team's curator insight, November 1, 2014 2:31 PM

Philippe Potentiellement nterssant

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Discovery Opens Door for Quantum Dots in Photodetectors, Sensors and Lasers

Discovery Opens Door for Quantum Dots in Photodetectors, Sensors and Lasers | Amazing Science | Scoop.it

Researchers at the National Institute of Standards and Technology (NIST) have shown that by bringing gold nanoparticles close to the dots and using a DNA template to control the distances, the intensity of a quantum dot's fluorescence can be predictably increased or decreased. Their research was published in Angewandte Chemie. This breakthrough opens a potential path to using quantum dots as a component in better photodetectors, chemical sensors and nanoscale lasers.

 

Anyone who has tried to tune a radio knows that moving their hands toward or away from the antenna can improve or ruin the reception. Although the reasons are well understood, controlling this strange effect is difficult, even with hundred-year-old radio technology. Similarly, nanotechnology researchers have been frustrated trying to control the light emitted from quantum dots, which brighten or dim with the proximity of other particles.

 

The NIST team developed ways to accurately and precisely place different kinds of nanoparticles near each other and to measure the behavior of the resulting nanoscale constructs. Because nanoparticle-based inventions may require multiple types of particles to work together, it is crucial to have reliable methods to assemble them and to understand how they interact.

 

The researchers looked at two types of nanoparticles, quantum dots, which glow with fluorescent light when illuminated, and gold nanoparticles, which have long been known to enhance the intensity of light around them. The two could work together to make nanoscale sensors built using rectangles of woven DNA strands, formed using a technique called "DNA origami."

 

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Controlling Particles for Directed Self-Assembly of Colloidal Crystals

Controlling Particles for Directed Self-Assembly of Colloidal Crystals | Amazing Science | Scoop.it

Researchers from the NIST Center for Nanoscale Science and Technology and the Johns Hopkins University have developed a technique to reliably manipulate hundreds of individual micrometer-sized colloid particles to create crystals with controlled dimensions.*  The accomplishment is an important milestone for understanding how to direct and control the assembly of microscale and nanoscale objects for nanomanufacturing applications.

 

The experiment uses four electrodes patterned on a microscope coverslip to move the micrometer-sized particles suspended in liquid by applying a combination of AC and DC electric fields.  Using a nonuniform, high-frequency AC field, the dielectrophoretic forces exerted on the dielectric particles are tuned to adjust the strength of their attraction to a collection area in the center of the electrodes.  When these forces are low enough, electrophoretic-electroosmotic flows induced by applying a DC field allow the researchers to selectively remove particles from the area and trim the particle assemblies to a chosen size and shape.

 

By independently varying the AC and DC electrode potentials, the researchers can direct the self-assembly of two-dimensional (2D) rafts made of precise numbers of particles; i.e., 2D colloidal crystals.  Once the desired crystal size is reached, the attractive forces holding the particles in the collection area are increased to stabilize the structure.  An important component of this work is the application of a computer vision-based, real-time feedback system that dynamically adjusts the AC and DC fields to automate the directed assembly process.

 

This work shows how the combination of multiple actuators offers extra degrees of freedom that can be used to manipulate ensembles of colloidal components to create desired sizes and shapes.  The researchers are now developing measurement methods sensitive enough to track nanometer-scale structures that will allow these methods to be extended to control the assembly of nanoscale materials.

 

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Drinking water unexpectedly rich in microbial life when investigated with flow cytometry

Drinking water unexpectedly rich in microbial life when investigated with flow cytometry | Amazing Science | Scoop.it

Flow cytometry (FCM) can now be officially used for the quantification of microbial cells in drinking water. The new analytical method – developed at Eawag and extensively tested both in Switzerland and abroad – has been incorporated into the Swiss Food Compendium (SLMB) by the Federal Office of Public Health (FOPH). FCM provides much more realistic results than the conventional method, in which bacterial colonies are grown on agar plates. The results demonstrate that even good-quality drinking water harbours 100 to 10,000 times more living cells than the conventional plate count method would suggest.

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Novel Nanosized Magnets for Controlled and Targeted Release of Drugs

Novel Nanosized Magnets for Controlled and Targeted Release of Drugs | Amazing Science | Scoop.it

Certain drugs are toxic by nature. For example, anti-cancer drugs developed to kill diseased cells also harm healthy ones. To limit the side effects of chemotherapy, it would be a great step forward if it were possible to release a drug only in the affected area of the body. In the context of the National Research Programme "Smart Materials" (NRP 62) - a cooperation between the SNSF and the Commission for Technology and Innovation (CTI) - researchers of ETH Lausanne, the Adolphe Merkle Institute and the University Hospital of Geneva have discovered a method that might represent an important step towards the development of an intelligent drug of this kind. By combining their expert knowledge in the areas of material sciences, biological nanomaterials and medicine, they were able to prove the feasibility of using a nanovehicle to transport drugs and release them in a controlled manner.

 

This nanocontainer is a liposome, which takes the shape of a vesicle. It has a diameter of 100 to 200 nanometers and is 100 times smaller than a human cell. The membrane of the vesicle is composed of phospholipids and the inside of the vesicle offers room for the drug. On the surface of the liposome, specific molecules help to target malignant cells and to hide the nanocontainer from the immune system, which might otherwise consider it a foreign entity and seek to destroy it. Now the researchers only needed to discover a mechanism to open up the membrane at will.

 

This is exactly what the researchers succeeded in doing. How they did it? By integrating into the liposome membrane superparamagnetic iron oxide nanoparticles (SPION), which only become magnetic in the presence of an external magnetic field. Once they are in the field, the SPION heat up. The heat makes the membrane permeable and the drug is released.

 

Researchers proved the feasibility of such a nanovehicle by releasing in a controlled manner a coloured substance contained in the liposomes. "We can really talk of nanomedicine in this context because, by exploiting superparamagnetism, we are exploiting a quantum effect which only exists at the level of nanoparticles," explains Heinrich Hofmann of the Powder Technology Laboratory of EPFL. SPION are also an excellent contrast agent in magnetic resonance imaging (MRI). A simple MRI shows the location of the SPION and allows for the release of the drug once it has reached the targeted spot.

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Tapeworm eggs discovered in 270 million year old fossil shark feces

Tapeworm eggs discovered in 270 million year old fossil shark feces | Amazing Science | Scoop.it

A cluster of tapeworm eggs discovered in 270-million-year-old fossilized shark feces suggests that intestinal parasites in vertebrates are much older than previously known.

 

Remains of such parasites in vertebrates from this era are rare- of 500 samples examined, only one revealed the tapeworm eggs. This particular discovery helps establish a timeline for the evolution of present-day parasitic tapeworms that occur in foods like pork, fish and beef. The fossilized eggs were found in a cluster very similar to those laid by modern tapeworms. Some of them are un-hatched and one contains what appears to be a developing larva. According to the study, "This discovery shows that the fossil record of vertebrate intestinal parasites is much older than was previously known and occurred at least 270-300 million years ago." The fossil described in this study is from Middle-Late Permian times, a period followed by the largest mass extinction known, when nearly 90% of marine species and 70% of terrestrial species died out.

 

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Physicists create world’s first multiverse of universes in the lab inside liquid metamaterial

Physicists create world’s first multiverse of universes in the lab inside liquid metamaterial | Amazing Science | Scoop.it

Researchers exploit the strange properties of a liquid metamaterial to watch Minkowski spacetimes leap in out and of existence.

 

Metamaterials are synthetic substances with nanoscale structures that manipulate light. This ability to steer photons makes them the enabling technology behind invisibility cloaks and has generated intense interest from researchers.

 

The ability to guide light has more profound consequences, however. Various theoreticians have pointed out that there is a formal mathematical analogy between the way certain metamaterials bend light and the way spacetime does the same thing in general relativity. In fact, it ought to be possible to make metamaterials that mimic the behaviour of not only our own spacetime but also many others that cosmologist merely dream about.  

 

Indeed, a couple of years ago we looked at a suggestion by Igor Smolyaninov at the University of Maryland in College Park that it ought to be possible to use metamaterials to create a multiverse in which different regions of the material corresponded to universes with different properties.

 

Today, Smolyaninov and a couple of buddies announce the extraordinary news that they have done exactly this. They’ve created a metamaterial containing many “universes” that are mathematically analogous to our own, albeit in the three dimensions rather than four. “These regions behave as transient 2+1 dimensional Minkowski spacetimes which temporarily appear and disappear inside a larger metamaterial “multiverse”,” they say.

 

The experiment is relatively straightforward. Metamaterials are usually hard to engineer because they are based on nanoscale structures. However, Smolyaninov and pals have instead exploited the self-assembling nature of cobalt nanoparticles suspended in kerosene.   Cobalt is ferromagnetic so the nanoparticles tend to become aligned in a magnetic field. In fact, if the density of nanoparticles is high enough, the field causes them to line up in columns. When this happens, the nanocolumns form a metamaterial which is mathematically equivalent to a 2+1 Minkowski spacetime.

 

So light passing through behaves as if this region has one dimension of time, aligned with the nanocolumns, and two dimensions of space, perpendicular to the nanocolumns. That creates a single Minkowski universe. The trick that Smolyaninov and pals have pulled off is to create a multiverse containing many Minkowski spacetimes .

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Collision of protons with lead ions at LHC may have produced new type of matter (colored-glass condensate)

Collision of protons with lead ions at LHC may have produced new type of matter (colored-glass condensate) | Amazing Science | Scoop.it

When particle beams interact at high speeds, the collisions yield hundreds of new particles, most of which fly away from the collision point at close to the speed of light. However, the Compact Muon Solenoid (CMS) team at the LHC found that in a sample of 2 million lead-proton collisions, some pairs of particles flew away from each other in the same direction.

 

“Somehow they fly at the same direction even though it’s not clear how they can communicate their direction with one another. That has surprised many people, including us,” said MIT physics Professor Gunther Roland, who led the group.

 

Two years ago, MIT researchers observed the same distinctive pattern in proton-proton collisions when ions of lead or other heavy metals, such as gold or copper, collided with one another.

 

Heavy-ion collisions produce a wave of quark gluon plasma, the hot soup of particles that existed for the first few millionths of a second after the Big Bang. In the LHC, this wave forces some of the resulting particles away in the same direction.

 

However, quark-gluon plasma isn’t possible with lead-proton collisions. So it has been speculated that the proton-proton collisions in the study may produce a liquid-like wave of gluon known as colour-glass condensate. Gluons are elementary particles related to the strong force that sticks quarks together inside protons and neutrons.

 

The mechanism may depend on the phenomenon of quantum entanglement. Entangled gluon in the colour-glass condensate could explain how two particles can retain a connection even after they fly away from each other.

“You don’t expect quark gluon plasma effects with lead-proton collisions,” explained Roland. “It was supposed to be sort of a reference run – a run in which you can study background effects and then subtract them from the effects that you see in lead-lead collisions.”

 

Details of the discovery will be published in the journal Physical Review B

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Scientists developed a way to grow iron-oxidizing bacteria using electricity instead of iron

Scientists developed a way to grow iron-oxidizing bacteria using electricity instead of iron | Amazing Science | Scoop.it

The method, called electrochemical cultivation, supplies these bacteria with a steady supply of electrons that the bacteria use to respire, or "breathe." It opens the possibility that one day electricity generated from renewable sources like wind or solar could be funneled to iron oxidizing bacteria that combine it with carbon dioxide to create biofuels, capturing the energy as a useful, storable substance.

 

"It's a new way to cultivate a microorganism that's been very difficult to study. But the fact that these organisms can synthesize everything they need using only electricity makes us very interested in their abilities," says Daniel Bond of the BioTechnology Institute at the University of Minnesota -- Twin Cities, who co-authored the paper with Zarath Summers and Jeffrey Gralnick.

 

To "breathe," iron oxidizers take electrons off of dissolved iron, called Fe(II) -- a process that produces copious amounts of rust, called Fe(III). Iron-oxidizing bacteria are found around the world, almost anywhere an aerobic environment (with plenty of oxygen) meets an anaerobic environment (which lacks oxygen). They play a big role in the global cycling of iron and contribute to the corrosion of steel pipelines, bridges, piers, and ships, but their lifestyle at the interface of two very different habitats and the accumulation of cell-trapping Fe(III) makes iron oxidizers difficult to grow and study in the lab. Bond and his colleagues added the marine iron oxidizer Mariprofundus ferrooxydans PV-1, along with some nutrient medium, to an electrode carefully tuned to provide electrons at the same energy level, or potential, as Fe(II) would provide. The idea, says Bond, was to "fool the bacteria into thinking they're at the world's best buffet of Fe(II) atoms."

 

It worked. The bacteria multiplied and formed a film on the electrode, Bond says, and eventually they were able to grow M. ferrooxydans with no iron in the medium, proof that the bacteria were living off the electrons they absorbed from the electrode to capture carbon dioxide and replicate. And since the electron donor is a solid surface, say the authors, it's pretty likely that the bacterial electron-harvesting machinery is exposed on the outer membrane of the cell.

 

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David Wechsler's curator insight, May 14, 2013 12:07 PM

So in a way they're electritarians... another form of breathatarian :)

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Power of the brain: Kelvin Okafor pencil drawings amaze art critics

Power of the brain: Kelvin Okafor pencil drawings amaze art critics | Amazing Science | Scoop.it

A series of pencil drawings by a north London artist have been amazing art critics. Kelvin Okafor, from Tottenham, has scooped a number of national awards and exhibited at galleries across the country. The 27-year-old Middlesex University Fine Art graduate's drawings are often mistaken for photographs. He draws his painting just from memory.

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'Habitable Zone' for Alien Planets, and Possibly Life, Redefined

'Habitable Zone' for Alien Planets, and Possibly Life, Redefined | Amazing Science | Scoop.it

The habitable zone defines the region where a planet might be able to retain liquid water on its surface. Any closer to the star and water would vaporize away; any farther, and it would freeze to ice. But water in its liquid state is what scientists are after, since that is thought to be a prerequisite for life.

 

The new definition of the habitable zone is based on updated atmospheric databases called HITRAN (high-resolution transmission molecular absorption) and HITEMP (high-temperature spectroscopic absorption parameters), which give the absorption parameters of water and carbon dioxide — two properties that strongly influence the atmospheres of exoplanets, determining whether those planets could host liquid water.

 

The scientists cautioned that the habitable zone definition still does not take into account feedback effects from clouds, which will also affect a planet's habitability.

 

The previous habitable zone definitions were derived about 20 years ago by Penn State researcher James Kasting, who was also part of the team behind the updates. "At the time when he wrote that paper no exoplanets were discovered," Kopparapu told SPACE.com. "In 20 years, hundreds, maybe thousands have been discovered."

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No more blind spots: Researchers design new rearview mirror

No more blind spots: Researchers design new rearview mirror | Amazing Science | Scoop.it

Today's motor vehicles in the United States use two different types of mirrors for the driver and passenger sides. The driver's side mirror is flat so that objects viewed in it are undistorted and not optically reduced in size, allowing the operator to accurately judge an approaching-from-behind vehicle's separation distance and speed. Unfortunately, the optics of a flat mirror also create a blind spot, an area of limited vision around a vehicle that often leads to collisions during merges, lane changes, or turns. The passenger side mirror, on the other hand, possesses a spherical convex shape. While the small radius of curvature widens the field of view, it also causes any object seen in it to look smaller in size and farther away than it actually is. Because of this issue, passenger side mirrors on cars and trucks in the United States must be engraved with the safety warning, "Objects in mirror are closer than they appear." In the European Union, both driver and passenger side mirrors are aspheric (One that bulges more to one side than the other, creating two zones on the same mirror).

 

The inner zone—the section nearest the door—has a nearly perfect spherical shape, while the outer zone— the section farthest from the door—becomes less and less curved toward the edges. The outer zone of this aspheric design also produces a similar distance and size distortion seen in spherical convex designs. In an attempt to remedy this problem, some automotive manufacturers have installed a separate, small wide-angle mirror in the upper corner of side mirrors. This is a slightly domed square that provides a wide-angle view similar to a camera's fisheye lens. However, drivers often find this system to be a distracting as well as expensive addition.

 

A simpler design for a mirror that would be free of blind spots, have a wide field of view, and produce images that are accurately scaled to the true size of an approaching object—and work for both sides of a vehicle—has been proposed by researchers Hocheol Lee and Dohyun Kim at Hanbat National University in Korea and Sung Yi at Portland State University in Oregon. Their solution was to turn to a progressive additive optics technology commonly used in "no-line multifocal" eyeglasses that simultaneously corrects myopia (nearsightedness) and presbyopia (reduced focusing ability).

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Einstein’s Brain

Einstein’s Brain | Amazing Science | Scoop.it

Scientists have been studying Albert Einstein's dead brain for clues as to his genius. Einstein’s brain is of unexceptional size and its combination of a relatively wide and forward-projecting right frontal lobe with a relatively wide and posteriorly protruding left occipital lobe is the most prevalent pattern seen in right-handed adult males. Scientests have identified the sulci that delimit expansions of cortex (gyri or convolutions) on the external surfaces of all of the lobes of the brain and on the medial surfaces of both hemispheres. The morphology in some parts of Einstein’s cerebral cortex is highly unusual compared with control human brains for which sulcal patterns have been thoroughly described. To the extent possible, the blocks of brain from particularly interesting areas are identified on the ‘roadmap’ that was prepared when Einstein’s brain was sectioned, as a guide for researchers who may wish to explore the histological correlates of Einstein’s gross cortical morphology.


Contrary to earlier reports, newly available photographs reveal that Einstein’s brain is not spherical in shape. The surface area of Einstein’s inferior parietal lobule is larger on the left than the right side, whereas that of his superior parietal lobule appears markedly larger in the right hemisphere. The photographs also suggest that the primary somatosensory and motor cortices representing the face and tongue are differentially expanded in the left hemisphere, that the posterior ascending limb of the Sylvian fissure is separate from (rather than confluent with) the postcentral inferior sulcus, and that parietal opercula are present. Nevertheless, these findings are concordant with the earlier suggestion that unusual morphology in Einstein’s parietal lobes may have provided neurological substrates for his visuospatial and mathematical abilities.


These results also suggest that Einstein had relatively expanded prefrontal cortices, which may have provided underpinnings for some of his extraordinary cognitive abilities, including his product- ive use of thought experiments. From an evolutionary perspective, the specific parts of Einstein’s prefrontal cortex that appear to be differentially expanded are of interest because recent findings indicate that these same areas increased differentially in size and became neurologically reorganized at microanatomical levels during hominin evolution in association with the emergence of higher cog- nitive abilities. It would be interesting therefore to investigate the histological correlates of these (as well as parietal) regions of Einstein’s brain from the newly available slides. Future research on comparative primate neuroanatomy, paleoneurology and functional neuroanatomy will hopefully provide insight about some of the unusually convoluted parts of Einstein’s brain.

 

http://tinyurl.com/b2k6ee8

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