One in 70 million chance: Texas woman has 2 sets of identical twins Reply

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A Texas woman got a quadruple Valentine’s Day gift this year, giving birth to four babies — two sets of identical twins. The twins were not the result of fertility treatments, the hospital said. Each pair of twins shared a placenta, the hospital said. Identical twins result when a fertilized egg splits into two embryos. Twins occur in about 2% of all pregnancies. Of those, 30% are identical twins. The odds of having two sets of twins at once is about 1 in 70 million, said Dr. Alan Penzias, associate professor of obstetrics, gynecology and reproductive biology at Harvard Medical School.

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Astrochemists Trying To Decipher Mystery Molecules Discovered in Distant Galaxies Reply

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In late 2011, a team of NASA and European scientists recorded the “fingerprints” of mystery molecules in two distant galaxies, Andromeda and the Triangulum. Astronomers can count on one hand the number of galaxies examined so far for such fingerprints, which are thought to belong to large organic molecules (molecules that have at least 20 atoms or more), said the team’s leader, Martin Cordiner of NASA’s Goddard Center for Astrobiology. This is quite small compared to, say, a protein, but huge compared to a molecule of carbon monoxide, a very common molecule in space.

 

Figuring out exactly which molecules are leaving these clues, known as “diffuse interstellar bands” (DIBs), is a puzzle that initially seemed straightforward but has gone unsolved for nearly a hundred years. The answer is expected to help explain how stars, planets and life form, so settling the matter is as important to astronomers who specialize in chemistry and biology as determining the nature of dark matter is to the specialists in physics.
The significance of the first DIBs, recorded in 1922 in Mary Lea Heger’s Ph.D. thesis, was not immediately recognized. But once astronomers began systematic studies, starting with a 1934 paper by P. W. Merrill, they had every reason to believe the problem could be solved within a decade or two.

More than 400 DIBs have been documented since then. But not one has been identified with enough certainty for astronomers to consider its case closed.

“With this many diffuse bands, you’d think we astronomers would have enough clues to solve this problem,” muses Joseph Nuth, a senior scientist with the Goddard Center for Astrobiology who was not involved in this work. “Instead, it’s getting more mysterious as more data is gathered.” Detailed analyses of the bumps and wiggles of the DIBs, suggest that the molecules which give rise to DIBs—called “carriers”—are probably large.

Recently, more interest has been focused on at least one small molecule, a chain made from three carbon atoms and two hydrogen atoms (C3H2). This was tentatively identified with a pattern of DIBs.

On the list of DIB-related suspects, all molecules have one thing in common: they are organic, which means they are built largely from carbon. Carbon is great for building large numbers of molecules because it is available almost  everywhere. In space, only hydrogen, helium and oxygen are more plentiful. Here on Earth, we find carbon in the planet’s crust, the oceans, the atmosphere and all forms of life.

See on www.dailygalaxy.com

Kepler 37-b: The tiniest exoplanet ever spotted – the size of our moon Reply

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Kepler-37b is an exoplanet, or planet located outside the solar system, and is estimated to be a similar size to Earth’s moon, which is only 3475 kilometres in diameter.

 

Owing to this extremely small size and its highly irradiated surface, Kepler-37b is believed to be a rocky planet with no atmosphere or water, similar to Mercury. The Kepler spacecraft made the Kepler-37b finding possible. The spacecraft was launched in 2009 with the goal of determining how often rocky planets occur in the habitable zone around sun-like host stars in our galaxy.

 

Over 150,000 stars are continuously monitored for transits of planetary bodies. Over the course of 978 days of observations by the Kepler spacecraft, transit signals of three planets of the star Kepler-37, a slightly cooler and older star than our sun, were identified.

 

“While theoretically such small planets are expected, detection of tiny planet Kepler-37b is remarkable given its transit signal is detectable on less than 0.5 percent of stars observed by Kepler,” Professor Bedding said.

 

“Since the discovery of the first exoplanet we have known that other planetary systems can look quite unlike our own, but it is only now, thanks to the precision of the Kepler space telescope that we have been able to find planets smaller than the ones we see in our own solar system.”

 

Professor Bedding and Dr. Stello contributed to the analysis of Kepler-37, the star Kepler-37b orbits. “We analysed the frequencies of standing sound waves inside the star to tell its size in the same way that you could tell the difference in size of a violin and cello by the difference in the pitch of the sound they produce,” said Dr. Stello.

 

This asteroseismic analysis showed that the radius of Kepler-37 is about 20 percent smaller than the sun. “Knowing this stellar radius is very important because the accuracy with which we can measure the radius of the planet Kepler-37b is limited by how accurately we can calculate the radius of Kepler-37,” said Dr. Stello.

 

“Our work from here is to keep working with the planet team at NASA to make seismic analyses of planet-hosting stars, and there are some exciting results in the pipeline,” said Dr. Stello.

See on pda.sciencealert.com.au

Any Two Pages on the Web Are Connected By 19 Clicks or Less Reply

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No one knows for sure how many individual pages are on the web, but right now, it’s estimated that there are more than 14 billion. Recently, though, Hungarian physicist Albert-László Barabási discovered something surprising about this massive number: Like actors in Hollywood connected by Kevin Bacon, from every single one of these pages you can navigate to any other in 19 clicks or less.

 

Barabási’s findings involved a simulated model of the web that he created to better understand its structure. He discovered that of the roughly 1 trillion web documents in existence—the aforementioned 14 billion-plus pages, along with every image, video or other file hosted on every single one of them—the vast majority are poorly connected, linked to perhaps just a few other pages or documents.

 

Distributed across the entire web, though, are a minority of pages—search engines, indexes and aggregators—that are very highly connected and can be used to move from area of the web to another. These nodes serve as the “Kevin Bacons” of the web, allowing users to navigate from most areas to most others in less than 19 clicks.

 

Barabási credits this “small world” of the web to human nature—the fact that we tend to group into communities, whether in real life or the virtual world. The pages of the web aren’t linked randomly, he says: They’re organized in an interconnected hierarchy of organizational themes, including region, country and subject area.

 

Interestingly, this means that no matter how large the web grows, the same interconnectedness will rule. Barabási analyzed the network looking at a variety of levels—examining anywhere from a tiny slice to the full 1 trillion documents—and found that regardless of scale, the same 19-click-or-less rule applied.

See on blogs.smithsonianmag.com

Stanford scientists fit a light-emitting bioprobe in a single living cell without damage to the cell Reply

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If engineers at Stanford have their way, biological research may soon be transformed by a new class of light-emitting probes small enough to be injected into individual cells without harm to the host.

 

Welcome to biophotonics, a discipline at the confluence of engineering, biology and medicine in which light-based devices – lasers and light-emitting diodes (LEDs) – are opening up new avenues in the study and influence of living cells.

 

The team described their probe in a paper published online Feb. 13, 2013 by the journal Nano Letters. It is the first study to demonstrate that tiny, sophisticated devices known as light resonators can be inserted inside cells without damaging the cell. Even with a resonator embedded inside, a cell is able to function, migrate and reproduce as normal.

 

The researchers call their device a “nanobeam,” because it resembles a steel I-beam with a series of round holes etched through the center. This beam, however, is not massive, but measure only a few microns in length and just a few hundred nanometers in width and thickness. It looks a bit like a piece from an erector set of old. The holes through the beam act like a nanoscale hall of mirrors, focusing and amplifying light at the center of the beam in what are known as photonic cavities.

 

Structurally, the new device is a sandwich of extremely thin layers of the semiconductor gallium arsenide alternated with similarly thin layers of light-emitting crystal, a sort of photonic fuel known as quantum dots. The structure is carved out of chips or wafers, much like sculptures are chiseled out of rock. Once sculpted, the devices remain tethered to the thick substrate.

 

For biological applications, the thick, heavy substrate presents a serious hurdle for interfacing with single cells. The underlying and all-important nanocavities are locked in position on the rigid material and unable to penetrate cell walls.

 

Shambat’s breakthrough came when he was able to peel away the photonic nanobeams. He then glued the ultrathin photonic device to a fiberoptic cable with which he steers the needle-like probe toward and into the cell.

 

Once inserted in the cell, the probe emits light, which can be observed from outside. For engineers, it means that almost any application of these powerful photonic devices can be translated into the previously off-limits environment of the cell interior. In one finding that the authors describe as stunning, they loaded their nanobeams into cells and watched as the cells grew, migrated around the research environment and reproduced. Each time a cell divided, one of the daughter cells inherited the nanobeam from the parent and the beam continued to function as expected.

 

This inheritability frees researchers to study living cells over long periods of time, a research advantage not possible with existing detection techniques, which require cells be either dead or fixed in place.

 

“Our nanoscale probes can reside in cells for long periods of time, potentially providing sensor feedback or giving control signals to the cells down the road,” said Shambat. “We tracked one cell for eight days. That’s a long time for a single-cell study.”

 

See on news.stanford.edu

Time reversal findings may open doors to the future Reply

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Imagine a cell phone charger that recharges your phone remotely without even knowing where it is; a device that targets and destroys tumors, wherever they are in the body; or a security field that can disable electronics, even a listening device hiding in a prosthetic toe, without knowing where it is.

 

The figure shown demonstrates secure communication with nonlinear time-reversal of two different UMD images using electromagnetic waves (signals) each sent through a complicated wave scattering environment (brown box in the middle). The black boxes represent time-reversed signals that are not reconstructed after being scattered.

While these applications remain only dreams, researchers at the University of Maryland have come up with a sci-fi seeming technology that one day could make them real. Using a time-reversal technique, the team has discovered how to transmit power, sound or images to a nonlinear object without knowing the object’s exact location and without affecting objects around it. 

“That’s the magic of time reversal,” says Steven Anlage, a university physics professor involved in the project. “When you reverse the waveform’s direction in space and time, it follows the same path it took coming out and finds its way exactly back to the source.”

The time-reversal process is less like living the last five minutes over and more like playing a record backwards, explains Matthew Frazier, a postdoctoral research fellow in the university’s physics department. When a signal travels through the air, its waveforms scatter before an antenna picks it up. Recording the received signal and transmitting it backwards reverses the scatter and sends it back as a focused beam in space and time.

 

“If you go toward a secure building, they won’t let you take cell phones,” Frazier says, “So instead of checking everyone, they could detect the cell phone and send a lot of energy to to jam it.” What differentiates this research from other time-reversal projects, such as underwater communication, is that it focuses on nonlinear objects such as a cellphone, diode or even a rusty piece of metal. When the altered, nonlinear frequency of nonlinear objects is recorded, time-reversed and retransmitted, it creates a private communication channel, because other objects cannot understand the signal.

See on phys.org