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Although cardiac pacemakers have saved countless lives, they do have at least one shortcoming – like other electronic devices, their batteries wear out. When this happens, of course, surgery is required in order to replace the pacemaker. While some researchers are looking into ideas such as drawing power from blood sugar, Swiss scientists from the University of Bern have taken another approach. They’ve developed a wristwatch-inspired device that can power a pacemaker via the beating of the patient’s own heart.
Bern cardiologist Prof. Rolf Vogel first came up with the idea four years ago, and it has been in development ever since. The resulting prototype device wasn’t just inspired by an auto-winding wristwatch, but actually incorporates the mechanism of a commercially-available model. Such watches rely on the user’s arm movements to wind a mechanical spring. Once that spring is fully wound, it then unwinds to power a micro-generator inside the watch.
In the case of the Bern device, it’s sutured onto the heart’s myocardial muscle instead of being worn on the wrist, and its spring is wound by heart contractions instead of arm movements. When that spring unwinds, the resulting energy is buffered in a capacitor. That capacitor then powers a pacemaker, to which it is electrically wired.
According to the research team, the system has demonstrated a mean output power of 52 microwatts when implanted in a live 60-kg (132-lb) pig – that’s more than enough for most modern pacemakers, which consume about 10 microwatts.
They now hope to further miniaturize the technology, make it more sensitive to the motion of the heart, and build both its energy-harvesting and capacitor functions into a pacemaker. This all-in-one setup would do away with the need for electrical leads, which can fail in conventional pacemakers.
The research was presented this Sunday at the ESC (European Society of Cardiology) Congress, by PhD candidate and team member Adrian Zurbuchen. A similar device is being developed at the University of Michigan.
Euler is easily the most prolific mathematician of all time. The range and volume of his output is simply staggering. He published over 850 papers, almost all of substantial length, and more than 25 books and treatises. In 1907 the Swiss Academy of Sciences established the Euler Commission with the charge of publishing the complete body of work consisting of all of his papers, manuscripts, and correspondence. This project, known as Opera Omnia, began in 1911 and is still ongoing. His scientific publications, not counting his correspondence, run to over 70 volumes, each between approximately 300 and 600 pages. Thousands of pages of handwritten manuscripts are still not in print. Euler was in constant communication with all the great scientists of his day, and his correspondence covers several thousand pages.
Euler's powers of memory and concentration were legendary. He could recite the entire Aeneid word-for-word. He was not troubled by interruptions or distractions; in fact, he did much of his work with his young children playing at his feet. He was able to do prodigious calculations in his head, a necessity after he went blind. The contemporary French mathematician Condorcet tells the story of two of Euler's students who had independently summed seventeen terms of a complicated infinite series, only to disagree in the fiftieth decimal place; Euler settled the dispute by recomputing the sum in his head.
Further reading: http://www.ams.org/bookstore/pspdf/euler-prev.pdf
Programming synthetic cells for tasks such as production of biofuels, environmental remediation, and treatments for human diseases. Researchers at Rice University and the University of Kansas Medical Center are making genetic circuits that can perform complex tasks by swapping protein building blocks.
The modular genetic circuits, which are engineered from parts of otherwise unrelated bacterial genomes, can be set up to handle multiple chemical inputs simultaneously with a minimum of interference from their neighbors.
The work, reported in the American Chemical Society journal ACS Synthetic Biology, gives scientists more options as they design synthetic cells for specific tasks, such as production of biofuels, environmental remediation, or treatments for human diseases.
The researchers are creating complex genetic logic circuits similar to those used to build traditional computers and electrical devices. In a simple circuit, if one input and another input are both present (AND gate), the circuit carries out its instruction. With genetic circuitry based on this type of Boolean logic, a genetic logic circuit might prompt the creation of a specific protein when it senses two chemicals — or prompt a cell’s DNA to repress the creation of that protein.
Simple circuits have become easier to create as synthetic biologists develop more tools, but they require more sophisticated tools for complex problems. Rice’s Matthew Bennett and his colleagues are intent upon following a path similar to that of computer programmers, whose capabilities grew from simple Pong to the immersive worlds of modern games.
The first definitive defeat for a classical computer by a quantum computer could one day be achieved with a quantum device that runs an algorithm known as “boson sampling,” recently developed by researchers at MIT.
Boson sampling uses single photons of light and optical circuits to take samples from an exponentially large probability distribution, which has been proven to be extremely difficult for classical computers.
The snag: how to generate the dozens of single photons needed to run the algorithm.
Now researchers at the Centre for Quantum Photonics (CQP) at the University of Bristol with collaborators from the University of Queensland (UQ) and Imperial College London say they have discovered how.
“We realized we could chain together many standard two-photon sources in such a way as to give a dramatic boost to the number of photons generated,” said CQP research leader Anthony Laing, a research fellow at the Centre for Quantum Photonics in the University of Bristol’s School of Physics.
Details of the research are in a paper published in Physical Review Letters.
Archaeologists set out Monday to use a revolutionary new deep sea diving suit to explore the ancient shipwreck where one of the most remarkable scientific objects of antiquity was found. The so-called Antikythera Mechanism, a 2nd-century BC device known as the world's oldest computer, was discovered by sponge divers in 1900 off a remote Greek island in the Aegean.
The highly complex mechanism of up to 40 bronze cogs and gears was used by the ancient Greeks to track the cycles of the solar system. It took another 1,500 years for an astrological clock of similar sophistication to be made in Europe.
A growing “dead zone” in the middle of the Arabian Sea has allowed plankton uniquely suited to low- oxygen water to take over the base of the food chain. Their rise to dominance over the last decade could be disastrous for the predator fish that sustain 120 million people living on the sea’s edge.
“These blooms are massive, appear year after year, and could be devastating to the Arabian Sea ecosystem over the long-term,” said the study’s lead author, Helga do Rosario Gomes, a biogeochemist at Lamont-Doherty.
Until recently, photosynthetic diatoms supported the Arabian Sea food chain. Zooplankton grazed on the diatoms, a type of algae, and were in turn eaten by fish. In the early 2000s, it all changed. The researchers began to see vast blooms of Noctiluca and a steep drop in diatoms and dissolved oxygen in the water column. Within a decade, Noctiluca had virtually replaced diatoms at the base of the food chain, marking the start of a colossal ecosystem shift.
In August 2003, an experiment at the KEKB particle accelerator in Japan found hints of an unexpected particle: A composite of elementary building blocks called quarks, it contained not two quarks like mesons or three like the protons and neutrons that constitute all visible matter, but four — a number that theoretical physicists had come to think the laws of nature did not permit. This candidate “tetraquark” disintegrated so quickly that it seemed a stretch to call it a particle at all. But as similar formations appeared in experiments around the world, they incited a fierce debate among experts about the correct picture of matter at the quantum scale. Most believed tetraquarks were a new kind of miniature molecule — essentially, two orbiting mesons, each made of one regular quark and one antimatter quark, or antiquark — while a smaller contingent saw them as stand-alone particles in which the two quarks and two antiquarks overlapped in the same small volume of space.
All parties remained uncertain that tetraquarks were real — until one turned up in data from the Large Hadron Collider, the 17-mile, proton-smashing ring near Geneva. Detailed measurements reported in June in Physical Review Letters confirm that the particle, which was first detected in 2007 at the accelerator in Japan and designated Z(4430), is unambiguously a tetraquark. Now, the discovery is forcing physicists to extend their simple picture of quark interactions, or finally replace it with a more nuanced understanding.
And, to mixed reviews, the properties of Z(4430) clearly favor the underdog “diquark model” and the hypothesis that tetraquarks are genuine particles. The existence of such states would suggest a menagerie of exotic “hadrons,” or particles made of quarks, including groupings of more than four. It would also attest to subtle quantum interactions that may shape the cores of hypothetical “quark stars,” the piping hot quark soup thought to have saturated the infant universe, and, closer to home, the proton and neutron building blocks of ordinary matter.
The exact structure of hadrons is hidden in the folds of a 40-year-old theory of the strong force called quantum chromodynamics (QCD), an easy-to-write-down but infinitely self-referential and thus unsolvable set of equations. No one understands why QCD’s boundless complexity seems equivalent to the quark model, or in other words, why the dynamic confluence of quarks and gluons known as a proton “somehow behaves as if it’s a simple composite of three particles,” Braaten said. Up to now, all hadrons feigned such simplicity. Tetraquarks, which the renowned theorists Edward Witten and Sidney Coleman mistakenly argued in the 1970s were inconsistent with a simplified analogue of QCD, have turned out to be the first manifestations of the theory that aren’t also captured by the quark model.
Now, rather than abandon the quark model altogether, proponents of the molecular and diquark models hope to extend it to encompass the new discoveries.
The quest to create camouflaging metamaterials that can “see” colors and automatically blend into the background is one step closer to reality, thanks to a breakthrough color-display technology unveiled this week by Rice University‘s Laboratory for Nanophotonics (LANP).
The new full-color display technology uses aluminum nanorods to create the vivid red, blue and green hues found in today’s top-of-the-line LCD televisions and monitors.
The technology is described in a new study in the Early Edition of the Proceedings of the National Academy of Sciences (PNAS) (open access).
The breakthrough is the latest in a string of recent discoveries by a Rice-led team that set out in 2010 to create metamaterials capable of mimicking the camouflage abilities of cephalopods — the family of marine creatures that includes squid, octopus and cuttlefish.
“Our goal is to learn from these amazing animals so that we could create new materials with the same kind of distributed light-sensing and processing abilities that they appear to have in their skins,” said LANP Director Naomi Halas, a co-author of the PNAS study.
She is the principal investigator on a $6 million Office of Naval Research grant for a multi-institutional team that includes marine biologists Roger Hanlon of the Marine Biological Laboratory in Woods Hole, Mass., and Thomas Cronin of the University of Maryland, Baltimore County.
“We know cephalopods have some of the same proteins in their skin that we have in our retinas, so part of our challenge, as engineers, is to build a material that can ‘see’ light the way their skin sees it, and another challenge is designing systems that can react and display vivid camouflage patterns,” Halas said.
LANP’s new color display technology delivers bright red, blue and green hues from five-micron-square pixels that each contains several hundred aluminum nanorods. By varying the length of the nanorods and the spacing between them, LANP researchers Stephan Link and Jana Olson showed they could create pixels that produced dozens of colors, including rich tones of red, green and blue that are comparable to those found in high-definition LCD displays.
“Aluminum is useful because it’s compatible with microelectronic production methods, but until now the tones produced by plasmonic aluminum nanorods have been muted and washed out,” said Link, associate professor of chemistry at Rice and the lead researcher on the PNAS study. “The key advancement here was to place the nanorods in an ordered array.”
Maze tests reveal subtle advantage bestowed by human FOXP2 gene
As a uniquely human trait, language has long baffled evolutionary biologists. Not until FOXP2 was linked to a genetic disorder that caused problems in forming words could they even begin to study language’s roots in our genes. Soon after that discovery, a team at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, discovered that just two bases, the letters that make up DNA, distinguished the human and chimp versions of FOXP2.
To try to determine how those changes influenced the gene's function, that group put the human version of the gene in mice. In 2009, they observed that these "humanized" mice produced more frequent and complex alarm calls, suggesting the human mutations may have been involved in the evolution of more complex speech.
Another study showed that humanized mice have different activity in the part of the brain called the striatum, which is involved in learning, among other tasks. But the details of how the human FOXP2 mutations might affect real-world learning remained murky. To solve the mystery, the Max Planck researchers sent graduate student Christiane Schreiweis to work with Ann Graybiel, a neuroscientist at the Massachusetts Institute of Technology in Cambridge. She's an expert in testing mouse smarts by seeing how quickly they can learn to find rewards in mazes.
In humans and other animals, learning occurs in two ways, Graybiel explains. The first requires breaking the task at hand into distinct steps and performing them one at a time. For example, to learn to ride a bike, you first need to remember to hold the handlebars straight, then to put your feet on the pedals, and finally push with your legs to make the pedals go around. At some point, though, these step-by-step movements become habit and you switch to the second type of learning, which is based on unconscious repetition. Now, your bike riding improves simply by repeating the task, rather than thinking through each step.
To figure out which type of learning may have been aided by the changes in the human version of FOXP2, Schreiweis tested humanized mice in mazes. In some cases, the mice were required to remember that turning right always led to a reward, indicating that they had acquired the repetitive habit of turning right and their skill had become “unconscious.” In other cases, they had to look around and figure out that the reward was always on the east arm of the maze, a task that required the behavioral flexibility of step-by-step learning. That’s because, depending on where in the maze the mouse started, it had to look around to figure out where to go.
When humanized mice and wild mice were put in mazes that engaged both types of learning,the humanized mice mastered the route to the reward faster than their wild counterparts, report Schreiweis, Graybiel, and their colleagues online today in the Proceedings of the National Academy of Sciences. But when the mice were engaged in just one type of learning, humanized and wild mice did equally well on all the tests. That was unexpected; the researchers forecast that the humanized mice would have some advantage in at least one of the learning types.
Conditions on Earth for the first 500 million years after it formed may have been surprisingly similar to the present day, complete with oceans, continents and active crustal plates.
This alternate view of Earth’s first geologic eon, called the Hadean, has gained substantial new support from the first detailed comparison of zircon crystals that formed more than 4 billion years ago with those formed contemporaneously in Iceland, which has been proposed as a possible geological analog for early Earth.
The study was conducted by a team of geologists directed by Calvin Miller, the William R. Kenan Jr. Professor of Earth and Environmental Sciences at Vanderbilt University, and published online this weekend by the journal Earth and Planetary Science Letters in a paper titled, “Iceland is not a magmatic analog for the Hadean: Evidence from the zircon record.”
From the early 20th century up through the 1980’s, geologists generally agreed that conditions during the Hadean period were utterly hostile to life. Inability to find rock formations from the period led them to conclude that early Earth was hellishly hot, either entirely molten or subject to such intense asteroid bombardment that any rocks that formed were rapidly remelted. As a result, they pictured the surface of the Earth as covered by a giant “magma ocean.”
Two schools of thought have emerged: One argues that Hadean Earth was surprisingly similar to the present day. The other maintains that, although it was less hostile than formerly believed, early Earth was nonetheless a foreign-seeming and formidable place, similar to the hottest, most extreme, geologic environments of today. A popular analog is Iceland, where substantial amounts of crust are forming from basaltic magma that is much hotter than the magmas that built most of Earth’s current continental crust.
“We reasoned that the only concrete evidence for what the Hadean was like came from the only known survivors: zircon crystals – and yet no one had investigated Icelandic zircon to compare their telltale compositions to those that are more than 4 billion years old, or with zircon from other modern environments,” said Miller.
The largest spacecraft welding tool in the world, the Vertical Assembly Center officially is open for business at NASA's Michoud Assembly Facility in New Orleans. The 170-foot-tall, 78-foot-wide giant completes a world-class welding toolkit that will be used to build the core stage of America's next great rocket, the Space Launch System (SLS).
SLS will be the most powerful rocket ever built for deep space missions, including to an asteroid and eventually Mars. The core stage, towering more than 200 feet tall (61 meters) with a diameter of 27.6 feet (8.4 meters), will store cryogenic liquid hydrogen and liquid oxygen that will feed the rocket's four RS-25 engines.
"This rocket is a game changer in terms of deep space exploration and will launch NASA astronauts to investigate asteroids and explore the surface of Mars while opening new possibilities for science missions, as well," said NASA Administrator Charles Bolden during a ribbon-cutting ceremony at Michoud Friday.
The Vertical Assembly Center is part of a family of state-of-the-art tools designed to weld the core stage of SLS. It will join domes, rings and barrels to complete the tanks or dry structure assemblies. It also will be used to perform evaluations on the completed welds. Boeing is the prime contractor for the SLS core stage, including avionics.
"The SLS Program continues to make significant progress," said Todd May, SLS program manager. "The core stage and boosters have both completed critical design review, and NASA recently approved the SLS Program's progression from formulation to development. This is a major milestone for the program and proof the first new design for SLS is mature enough for production."
A new study published in The Journal of Geology provides support for the theory that a cosmic impact event over North America some 13,000 years ago caused a major period of climate change known as the Younger Dryas stadial, or “Big Freeze.”
Around 12,800 years ago, a sudden, catastrophic event plunged much of the Earth into a period of cold climatic conditions and drought. This drastic climate change—the Younger Dryas—coincided with the extinction of Pleistocene megafauna, such as the saber-tooth cats and the mastodon, and resulted in major declines in prehistoric human populations, including the termination of the Clovis culture.
With limited evidence, several rival theories have been proposed about the event that sparked this period, such as a collapse of the North American ice sheets, a major volcanic eruption, or a solar flare.
However, in a study published in The Journal of Geology, an international group of scientists analyzing existing and new evidence have determined a cosmic impact event, such as a comet or meteorite, to be the only plausible hypothesis to explain all the unusual occurrences at the onset of the Younger Dryas period.
Researchers from 21 universities in 6 countries believe the key to the mystery of the Big Freeze lies in nanodiamonds scattered across Europe, North America, and portions of South America, in a 50-million-square-kilometer area known as the Younger Dryas Boundary (YDB) field.
Microscopic nanodiamonds, melt-glass, carbon spherules, and other high-temperature materials are found in abundance throughout the YDB field, in a thin layer located only meters from the Earth’s surface. Because these materials formed at temperatures in excess of 2200 degrees Celsius, the fact they are present together so near to the surface suggests they were likely created by a major extraterrestrial impact event.
In addition to providing support for the cosmic impact event hypothesis, the study also offers evidence to reject alternate hypotheses for the formation of the YDB nanodiamonds, such as by wildfires, volcanism, or meteoric flux.
The team’s findings serve to settle the debate about the presence of nanodiamonds in the YDB field and challenge existing paradigms across multiple disciplines, including impact dynamics, archaeology, paleontology, limnology, and palynology.
With a new therapeutic product, researchers have managed to cure arthritis in mice for the first time. The scientists are now planning to test the efficacy of the drug in humans. Rheumatoid arthritis is a condition that causes painful inflammation of several joints in the body. The joint capsule becomes swollen, and the disease can also destroy cartilage and bone as it progresses. Rheumatoid arthritis affects 0.5% to 1% of the world's population.
Antibody–cytokine fusion proteins (immunocytokines) are innovative biopharmaceutical agents, which are being considered for the therapy of cancer and chronic inflammatory conditions. Immunomodulatory fusion proteins capable of selective localization at the sites of rheumatoid arthritis (RA) are of particular interest, as they may increase the therapeutic index of the cytokine payload. The F8 antibody recognizes the alternatively spliced extra domain A of fibronectin, a marker of angiogenesis, which is strongly overexpressed at sites of arthritis. In this study, scientists investigated the targeting and therapeutic activity of the immunocytokine F8-IL4 in the mouse model of collagen-induced arthritis. Different combination regimes were tested and evaluated by the analysis of serum and tissue cytokine levels. They were able to show that F8-IL4 selectively localizes to neovascular structures at sites of rheumatoid arthritis in the mouse, leading to high local concentrations of IL4. When used in combination with dexamethasone, F8-IL4 was able to cure mice with established collagen-induced arthritis. Response to treatment was associated with an elevation of IL13 levels and decreased IL6 plasma concentrations. A fully human version of F8-IL4 is currently being developed for clinical investigations and clinical trials in humans will hopefully start soon.
"As a result of combination with the antibody, IL-4 reaches the site of the disease when the fusion molecule is injected into the body," says pharmacist Teresa Hemmerle, who has just completed her dissertation in the group of Dario Neri, a professor at the Institute of Pharmaceutical Sciences. Together with Fabia Doll, also a PhD pharmacist at ETH, she is the lead author of the study. "It allows us to concentrate the active substance at the site of the disease. The concentration in the rest of the body is minimal, which reduces side-effects," she says.
Two prominent U.S. hospitals are preparing to launch trials with diabetics and chronic disease patients using Apple Inc's (AAPL.O) HealthKit, offering a glimpse of how the iPhone maker's ambitious take on healthcare will work in practice.
HealthKit, which is still under development, is the center of a new healthcare system by Apple. Regulated medical devices, such as glucose monitors with accompanying iPhone apps, can send information to HealthKit. With a patient's consent, Apple's service gathers data from various health apps so that it can be viewed by doctors in one place.
Stanford University Hospital doctors said they are working with Apple to let physicians track blood sugar levels for children with diabetes. Duke University is developing a pilot to track blood pressure, weight and other measurements for patients with cancer or heart disease.
The goal is to improve the accuracy and speed of reporting data, which often is done by phone and fax now. Potentially doctors would be able to warn patients of an impending problem. The pilot programs will be rolled out in the coming weeks.
Apple last week mentioned the trials in a news release announcing the latest version of its operating system for phones and tablets, iOS 8, but this is the first time any details have been made public. Apple declined to comment for this article.
Apple aims eventually to work with health care providers across the United States, including hospitals which are experimenting with using technology to improve preventative care to lower healthcare cost and make patients healthier.
Reuters previously reported that Apple is in talks with other U.S. hospitals. Stanford Children's Chief Medical Information Officer Christopher Longhurst told Reuters that Stanford and Duke were among the furthest along.
Longhurst said that in the first Stanford trial, young patients with Type 1 diabetes will be sent home with an iPod touch to monitor blood sugar levels between doctor's visits.
HealthKit makes a critical link between measuring devices, including those used at home by patients, and medical information services relied on by doctors, such as Epic Systems Corp, a partner already announced by Apple.
Medical device makers are taking part in the Stanford and Duke trials.
DexCom Inc (DXCM.O), which makes blood sugar monitoring equipment, is in talks with Apple, Stanford, and the U.S. Food and Drug Administration about integrating with HealthKit, said company Chief Technical Officer Jorge Valdes.
DexCom's device measures glucose levels through a tiny sensor inserted under the skin of the abdomen. That data is transmitted every five minutes to a hand-held receiver, which works with a blood glucose meter. The glucose measuring system then sends the information to DexCom's mobile app, on an iPhone, for instance.
Under the new system, HealthKit can scoop up the data from DexCom, as well as other app and device makers.
Data can be uploaded from HealthKit into Epic's "MyChart" application, where it can be viewed by clinicians in Epic's electronic health record.
Via Ray and Terry's
Astronomers using data from NASA’s Hubble Space Telescope and ground observation have found an unlikely object in an improbable place -- a monster black hole lurking inside one of the tiniest galaxies ever known.
The black hole is five times the mass of the one at the center of our Milky Way galaxy. It is inside one of the densest galaxies known to date -- the M60-UCD1 dwarf galaxy that crams 140 million stars within a diameter of about 300 light-years, which is only 1/500th of our galaxy’s diameter.
If you lived inside this dwarf galaxy, the night sky would dazzle with at least 1 million stars visible to the naked eye. Our nighttime sky as seen from Earth’s surface shows 4,000 stars.
The finding implies there are many other compact galaxies in the universe that contain supermassive black holes. The observation also suggests dwarf galaxies may actually be the stripped remnants of larger galaxies that were torn apart during collisions with other galaxies rather than small islands of stars born in isolation.
“We don’t know of any other way you could make a black hole so big in an object this small,” said University of Utah astronomer Anil Seth, lead author of an international study of the dwarf galaxy published in Thursday’s issue of the journal Nature.
Seth’s team of astronomers used the Hubble Space Telescope and the Gemini North 8-meter optical and infrared telescope on Hawaii’s Mauna Kea to observe M60-UCD1 and measure the black hole’s mass. The sharp Hubble images provide information about the galaxy’s diameter and stellar density. Gemini measures the stellar motions as affected by the black hole’s pull. These data are used to calculate the mass of the black hole.
Black holes are gravitationally collapsed, ultra-compact objects that have a gravitational pull so strong that even light cannot escape. Supermassive black holes -- those with the mass of at least one million stars like our sun -- are thought to be at the centers of many galaxies.
The black hole at the center of our Milky Way galaxy has the mass of four million suns. As heavy as that is, it is less than 0.01 percent of the Milky Way’s total mass. By comparison, the supermassive black hole at the center of M60-UCD1, which has the mass of 21 million suns, is a stunning 15 percent of the small galaxy’s total mass.
“That is pretty amazing, given that the Milky Way is 500 times larger and more than 1,000 times heavier than the dwarf galaxy M60-UCD1,” Seth said.
One explanation is that M60-UCD1 was once a large galaxy containing 10 billion stars, but then it passed very close to the center of an even larger galaxy, M60, and in that process all the stars and dark matter in the outer part of the galaxy were torn away and became part of M60.
The team believes that M60-UCD1 may eventually be pulled to fully merge with M60, which has its own monster black hole that weighs a whopping 4.5 billion solar masses, or more than 1,000 times bigger than the black hole in our galaxy. When that happens, the black holes in both galaxies also likely will merge. Both galaxies are 50 million light-years away.
A group of scientists in Chile has created* artificial biomembranes, mimicking those found in living organisms on silicon surfaces, a step toward creating bio-silicon interfaces, where biological “sensor” molecules can be printed onto a cheap silicon chip with integrated electronic circuits.
Described in The Journal of Chemical Physics from AIP Publishing, the artificial membranes have potential applications such as detecting bacterial contaminants in food, toxic pollution in the environment, and dangerous diseases .
The idea is to create a “biosensor that can transmit electrical signals through the membrane,” said María José Retamal, a Ph.D. student at Pontificia Universidad Católica de Chile and first author of the paper.
Lipid membranes separate distinct spaces within cells and define walls between neighboring cells — a functional compartmentalization that serves many physiological processes, protecting genetic material, regulating what comes in and out of cells, and maintaining the function of separate organs.
Synthetic membranes that mimic nature offer the possibility of containing membrane proteins — biological molecules that could be used for detecting toxins, diseases and many other biosensing applications.
More work is needed to standardize the process by which proteins are to be inserted in the membranes, to define the mechanism by which an electrical signal would be transmitted when a protein binds its target, and to calibrate how that signal is detected by the underlying circuitry, Retamal said.
* Retamal and her colleagues created the first artificial membrane without using solvents on a silicon support base. They chose silicon because of its low cost, wide availability and because its “hydrophobicity” (how much it repels water) can be controlled chemically, allowing them to build membranes on top.
Next they evaporated a chemical known as chitosan onto the silicon. Chitosan is derived from chitin, a sugar found in the shells of certain crustaceans, like lobsters or shrimp. Whole bags of the powder can be bought from chemical companies worldwide. They chose this ingredient for its ability to form a moisturizing matrix. It is insoluble in water, but chitosan is porous, so it is capable of retaining water.
Finally they evaporated a phospholipid molecule known as dipalmitoylphosphatidylcholine (DPPC) onto the chitosan-covered silicon substrate and showed that it formed a stable “bilayer,” the classic form of a membrane. Spectroscopy showed that these artificial membranes were stable over a wide range of temperatures.
It is difficult to find fault with a process that can create food from sunlight, water and air, but for many plants, there is room for improvement. Researchers have taken an important step towards enhancing photosynthesis by engineering plants with enzymes from blue-green algae that speed up the process of converting carbon dioxide into sugars. The results, published today in Nature1, surmount a daunting hurdle on the path to boosting plant yields — a goal that is taking on increasing importance as the world’s population grows.
“With the limited ability to increase land use for agriculture, there’s a huge interest in trying to improve yield across all the major crops,” says Steven Gutteridge, a research fellow at chemical firm DuPont’s crop-protection division in Newark, Delaware.
Researchers have long wanted to increase yields by targeting Rubisco, the enzyme responsible for converting carbon dioxide into sugar. Rubisco is possibly the most abundant protein on Earth, and can account for up to half of all the soluble protein found in a leaf.
But one reason for its abundance is its inefficiency: plants produce so much Rubisco in part to compensate for its slow catalysis. Some have estimated that tinkering with Rubisco and ways to boost the concentration of carbon dioxide around it could generate up to a 60% increase2 in the yields of crops such as rice and wheat. Plant geneticist Maureen Hanson of Cornell University in Ithaca, New York, and her colleagues decided to borrow a faster Rubisco from the cyanobacterium Synechococcus elongatus.
A team including Hanson and plant physiologist Martin Parry of Rothamsted Research in Harpenden, UK, shuttled bacterial Rubisco genes into the genome of the chloroplast — the cellular organelle where photosynthesis takes place — in the tobacco plant (Nicotiana tabacum), a common model organism for genetic-engineering research. In some of the plants the researchers also added a bacterial protein that is thought to help Rubisco to fold properly. In others, they added a bacterial protein that structurally supports Rubisco.
Both lines of tobacco were able to use the bacterial Rubisco for photosynthesis, and both converted CO2 to sugar faster than normal tobacco1. The work provides an important foundation for testing the hypothesis that a faster Rubisco can yield a more productive plant, says Donald Ort, a plant biologist at the University of Illinois at Urbana–Champaign.
Human herpesvirus 6, pictured above, is just one of numerous viruses found living in and on the bodies of healthy humans. The virus commonly causes illness in young children but is found in the mouths of some healthy young adults, where its presence indicates an active viral infection despite a lack of symptoms.
On average, healthy individuals carry about five types of viruses on their bodies, the researchers report online in BioMed Central Biology. The study is the first comprehensive analysis to describe the diversity of viruses in healthy people.
The research was conducted as part of the Human Microbiome Project, a major initiative funded by the National Institutes of Health (NIH) that largely has focused on cataloging the body's bacterial ecosystems. "Most everyone is familiar with the idea that a normal bacterial flora exists in the body," said study co-author Gregory Storch, MD, a virologist and chief of the Division of Pediatric Infectious Diseases. "Lots of people have asked whether there is a viral counterpart, and we haven't had a clear answer. But now we know there is a normal viral flora, and it's rich and complex."
In 102 healthy young adults ages 18 to 40, the researchers sampled up to five body habitats: nose, skin, mouth, stool and vagina. The study's subjects were nearly evenly split by gender. At least one virus was detected in 92 percent of the people sampled, and some individuals harbored 10 to 15 viruses.
"We were impressed by the number of viruses we found," said lead author Kristine M. Wylie, PhD, an instructor of pediatrics. "We only sampled up to five body sites in each person and would expect to see many more viruses if we had sampled the entire body."
Scientists led by George Weinstock, PhD, at Washington University's Genome Institute, sequenced the DNA of the viruses recovered from the body, finding that each individual had a distinct viral fingerprint. (Weinstock is now at The Jackson Laboratory in Connecticut.) About half of people were sampled at two or three points in time, and the researchers noted that some of the viruses established stable, low-level infections.
The researchers don't know yet whether the viruses have a positive or negative effect on overall health but speculate that in some cases, they may keep the immune system primed to respond to dangerous pathogens while in others, lingering viruses increase the risk of disease.
The modern European gene pool was formed when three ancient populations mixed within the last 7,000 years, Nature reports.
Blue-eyed, swarthy hunters mingled with brown-eyed, pale skinned farmers as the latter swept into Europe from the Near East. But another, mysterious population with Siberian affinities also contributed to the genetic landscape of the continent. The findings are based on analysis of genomes from nine ancient Europeans. Agriculture originated in the Near East - in modern Syria, Iraq and Israel - before expanding into Europe around 7,500 years ago.
Multiple lines of evidence suggested this new way of life was spread by a wave of migrants, who interbred with the indigenous European hunter-gatherers they encountered on the way. But assumptions about European origins were based largely on the genetic patterns of living people. The science of analysing genomic DNA from ancient bones has put some of the prevailing theories to the test, throwing up a few surprises.
In the new paper, Prof David Reich from the Harvard Medical School and colleagues studied the genomes of seven hunter-gatherers from Scandinavia, one hunter whose remains were found in a cave in Luxembourg and an early farmer from Stuttgart, Germany. The hunters arrived in Europe thousands of years before the advent of agriculture, hunkered down in southern refuges during the Ice Age and then expanded during a period called the Mesolithic, after the ice sheets had retreated from central and northern Europe.
Their genetic profile is not a good match for any modern group of people, suggesting they were caught up in the farming wave of advance. However, their genes live on in modern Europeans, to a greater extent in the north-east than in the south.
The early farmer genome showed a completely different pattern, however. Her genetic profile was a good match for modern people in Sardinia, and was rather different from the indigenous hunters.
But, puzzlingly, while the early farmers share genetic similarities with Near Eastern people at a global level, they are significantly different in other ways. Prof Reich suggests that more recent migrations in the farmers' "homeland" may have diluted their genetic signal in that region today.
Prof Reich explained: "The only way we'll be able to prove this is by getting ancient DNA samples along the potential trail from the Near East to Europe... and seeing if they genetically match these predictions or if they're different.
Researchers at Stanford exploited the newly developed precision gene editing technology known CRISPR-Cas9 into an anti-virus technology by cutting out Epstein-Barr virus from the host genome of infected cells. Infected cells successfully treated this way scale back proliferation caused by viral programs and engage in a self-destruct program known as “apoptosis”, or controlled cell death. EBV is known to express a “brake” protein that suppresses apoptosis, a way to evade natural defense mechanisms. The researchers also show importantly that there was no toxic effect on non-infected cells.
Epstein-Barr virus (EBV) is most often associated with mononucleosis but is also a cause of more serious conditions such as Burkitt’s lymphoma, nasopharyngeal cancer, and even autoimmune diseases. No therapy exists but the CRISPR-Cas9 study is a valuable avenue as it overcomes two challenges posed by the virus.
The first challenge is during the latent stage of its life cycle it integrates into the genome and exhibits few targets for intervention. In fact most therapeutics under development are focused on attacking the virus during its active “lytic” stage so are not expected to work for cells with virus in latent stage. In the latent stage the virus is still “on”, running a latency program that prompts the cell to proliferate.
The second challenge is that the virus encodes and expresses with the help of the host cell a “brake” protein BHRF1that stops the self-destruct signal stimulated by immune cells in effort to rid the body of cells that have become compromised. The “brake” signal is one reason why EBV is frequently found in cancers: under normal conditions cells that start off on the path to cancer by acquiring mutations get stopped by the cell’s natural ability to undergo “programmed cell death” but EBV halts this process.
The technology for CRISPR-Cas9 entails two parts. The first is the “cutting” enzyme, which is able to cut out pieces of viral DNA that has integrated into the host genome. The second is a “guide RNA” which is a nucleic acid template that matches the desired target, in this case parts of the EBV sequence. The researchers designed a CRISPR-Cas9 system that targets EBV based on its sequence in computer databases.
Once the cells were treated the researches found that latently infected cells no longer proliferated. To ensure that this was not a toxic effect of treatment, the same CRISPR-Cas9 system was applied to cells that lack EBV, in which case there was no effect on proliferation. This is an important point as some criticize CRISPR-Cas9 for its off-target effects in which unintentional cutting occurs.
An atomically thin, two-dimensional, ultrasensitive semiconductor material for biosensing developed by University of California Santa Barbara (UCSB) researchers promises to push the boundaries of biosensing technology in many fields, from health care to environmental protection to forensic industries.
It’s based on molybdenum disulfide, or molybdenite (MoS2), as an alternative to graphene. Molybdenum disulfide — commonly used as a dry lubricant — surpasses graphene’s already high sensitivity, offers better scalability, and lends itself to high-volume manufacturing, the researchers say. Results of their study have been published in ACS Nano.
“This invention has established the foundation for a new generation of ultrasensitive and low-cost biosensors that can eventually allow single-molecule detection — the holy grail of diagnostics and bioengineering research,” said Samir Mitragotri, co-author and professor of chemical engineering and director of the Center for Bioengineering at UCSB.
The key, according to UCSB professor of electrical and computer engineering Kaustav Banerjee, who led this research, is MoS2’s band gap, a characteristic of a material that determines its electrical conductivity, the minimum amount of energy required for conduction; i.e., for an electron to break free of its bound state in a material — the gap between bound and free.
Semiconductor materials have a small but nonzero band gap and can be switched between conductive and insulated states controllably. The larger the band gap, the better its ability to switch states and to insulate leakage current in an insulated state. MoS2’s wide band gap allows current to travel but also prevents leakage and results in more sensitive and accurate readings.
Graphene has attracted wide interest as a biosensor due to its two-dimensional structure (which allows for excellent electrostatic control of the transistor channel by the gate) and its high surface-to-volume ratio. However, the sensitivity of a field-effect transistor (FET) biosensor based on graphene is fundamentally limited by graphene’s zero (fully conductive) band gap, which results in increased leakage current, leading to reduced sensitivity, explained Banerjee, who is also the director of the Nanoelectronics Research Lab at UCSB.
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New research has determined that a single group of micro-organisms may be responsible for much of the world’s vitamin B12 production in the oceans, with implications for the global carbon cycle and climate change.
Although vitamin B12 is an essential molecule required by most life on this planet, it is only produced by a relatively small group of micro-organisms because it is so large and complex. For humans, vitamin B12 plays a key role in maintaining the brain and nervous systems, as well as DNA synthesis in cells throughout the body.
Professors Andew Doxey and Josh Neufeld, from the Faculty of Science at the University of Waterloo, led a study that discovered that Thaumarchaeota are likely dominant vitamin B12 producers. This group from the Archea domain has never before been associated with vitamin B12 synthesis.
"We assumed that most major global sources of something as fundamental as vitamin B12 would have already been characterized, and so this finding changes how we think about global production of this important vitamin," said Professor Doxey.
The researchers, both of whom teach in the Department of Biology at Waterloo, used computational methods to search through vast amounts of sequenced environmental DNA for the genes that make vitamin B12, identifying the likely producers in marine and freshwater environments.
"Because Thaumarchaeota are among the most abundant organisms on the planet, especially in marine environments, their contribution to vitamin B12 production have enormous implications for ecology and metabolism in the oceans," said Professor Neufeld.
The availability of vitamin B12 may control how much or how little biological productivity by phytoplankton takes place in the oceans. Phytoplankton remove carbon dioxide from the atmosphere through photosynthesis, much like plants and trees, thus reducing the atmospheric concentration of this greenhouse gas, the largest contributor to global warming.
The research also found that proportions of archaeal B12synthesis genes increased with ocean depth and were more prevalent in winter and polar waters, suggesting that archaeal vitamin B12 may be critical for the survival of other species in both the deep and cold marine environments.
An interdisciplinary team of scientists and engineers has developed a thin, flexible 4-layer material that autonomously camouflages itself to the surroundings by optically evaluating the background and changing its pattern to match much like how the skin of an octopus or chameleon does so in the wild. The system mimics different patterns of background quickly within 1 to 2 seconds. To date there has been no other similar system which includes the crucial capabilities of sensing and actuation in a distributed manner.
The inspiration for this creation came from understanding of the skin of cephalopods (examples of which include octopus, squid, cuttlefish etc.), sea creatures that mimic in full color and with greater resolution the appearance of their environment. Celphalopod skin has faster response times, from 250-750 milliseconds. The prototype material is much simpler, arranged as an array of 16 x 16 relatively large, 1 mm square “pixels” that change from black to white and back again.
Response times are slower too in the 1 to 2 second range.
There is no overall camera system to detect the background and no central processing that controls the patterning of the material. In real octopuses, the eyes are involved, but the skin has its own photoreceptors similar to those found in the retina. The designed layered material works in the latter, distributed way, by integrating distributed optical sensors that monitor its surroundings and then commanding independent optical “actuators” to adapt dynamically.
In future, some diseases might be diagnosed earlier and treated more effectively. Researchers at the Max Planck Institute for the Science of Light in Erlangen have developed an optical method that makes individual proteins, such as the proteins characteristic of some cancers, visible. Other methods that achieve this only work if the target biomolecules have first been labelled with fluorescent tags; In general, however, that approach is difficult or even impossible. By contrast, with their method, coined iSCAT, the researchers in Erlangen are able to directly detect the scattered light of individual proteins via their shadows. The method could not only make biomedical diagnoses more sensitive, but also provide new insights into fundamental biological processes.
A biosensor for the scattered light of individual unmarked biomolecules such as proteins and tumour markers may facilitate medical diagnosis. The biodetector, that a team led by V. Sandoghdar has developed at the Max Planck Institute for the Science of Light, uses the interferometric method iSCAT.
Vahid Sandoghdar, Director at the Max Planck Institute for the Science of Light, and Marek Piliarik, a post doc in Sandoghdar’s division, are now able to produce a much clearer image without the need for elaborate attachment of luminous markers to the target proteins. This is possible thanks to iSCAT, short for interferometric detection of scattering. The researchers shine laser light onto a microscope slide on which the relevant proteins have been captured with appropriate biochemical lures. The proteins scatter the laser light, thus casting a shadow, albeit a very weak one. “iSCAT not only promises more sensitive diagnosis of diseases such as cancers, but will also shed light on many fundamental biochemical processes in nature,” says Vahid Sandoghdar.
The Erlangen-based researchers have succeeded to achieve a high level of sensitivity for individual proteins by applying some tricks, and because they were not hampered by a misconception that a lot of other scientists have: “Until now it was thought that if you want to detect scattered light from nanoparticles, you have to eliminate all background light,” explains Vahid Sandoghdar. “However, in recent years we’ve realized that it is more advantageous to illuminate the sample strongly and visualize the feeble signal of a tiny nanoparticle as a shadow against the intense background light.” The researchers therefore allow the background light to interfere with the weak scattered light so that the desired signal is amplified.
However, at this stage they are still unable to detect the shadows of a single protein in the interference image, because the pattern is akin to that of a television broadcast in black and white that is distorted by a lot of noise. The interferometric detection method is so sensitive that any small roughness or contamination of the sample carrier will also cast a shadow that could in fact swamp the protein signal.
Nevertheless, this difficulty did not put off the two researchers. They have learned to eliminate the noise by applying a second trick. They take a snapshot with the iSCAT microscope not only after they have dripped a solution containing the desired protein onto the sample holder but also before. “Since most of the optical noise generated by nanoscopic irregularities of the sample do not change, we can subtract one image from the other and thus eliminate the noise,” says Piliarik. The target proteins then stand out clearly from the background as dark spots, even though the shadow of the protein is only one ten-thousandth or even one hundred-thousandth as dark as the background.
Marek Piliarik and Vahid Sandoghdar are able to detect various proteins as shadows under the microscope not only in pure solutions. They can also home in on individual proteins in mixtures containing concentrations of other proteins that are up to 2000 times greater.
New research shows that schizophrenia isn’t a single disease but a group of eight genetically distinct disorders, each with its own set of symptoms. The finding could be a first step toward improved diagnosis and treatment for the debilitating psychiatric illness.
The research at Washington University School of Medicine in St. Louis is reported online Sept. 15 in The American Journal of Psychiatry. About 80 percent of the risk for schizophrenia is known to be inherited, but scientists have struggled to identify specific genes for the condition.
Now, in a novel approach analyzing genetic influences on more than 4,000 people with schizophrenia, the research team has identified distinct gene clusters that contribute to eight different classes of schizophrenia.
“Genes don’t operate by themselves,” said C. Robert Cloninger, MD, PhD, one of the study’s senior investigators. “They function in concert much like an orchestra, and to understand how they’re working, you have to know not just who the members of the orchestra are but how they interact.”