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The new nanocarriers are just 15 nanometers in diameter, based on building blocks called amphiphilic polymers: they have both hydrophilic (water-loving, polar) and lipophilic (fat-loving) properties). That allows the nanocarriers to hold the guest molecules within their water-insoluble interior and use their water-soluble exterior to travel through an aqueous environment. And that makes the nanocarriers ideal for transferring molecules that would otherwise be insoluble in water.
They also emit a fluorescent signal that can be observed with a microscope, allowing for tracking and photographing the nanoparticles in the body.
“The size of these nanoparticles, their dynamic character and the fact that the reactions take place under normal biological conditions (at ambient temperature and neutral environment) makes these nanoparticles an ideal vehicle for the controlled activation of therapeutics, directly inside the cells,” says lead investigator Francisco Raymo, professor of chemistry in the University of Miami College of Arts and Sciences and UM laboratory for molecular photonics.
The next phase of this investigation involves demonstrating that this method can be used to achieve chemical reactions inside cells, instead of energy transfers.
Several DARPA programs are exploring innovative technologies and approaches that could supplement GPS to provide reliable, highly accurate real-time positioning, navigation and timing (PNT) data for military and civilian uses and deal with possible loss of GPS accuracy from solar storms or jamming, for example.
DARPA Director Arati Prabhakar said DARPA currently has five programs that focus on PNT-related technology.
Adaptable Navigation Systems (ANS) is developing new algorithms and architectures that can create better inertial measurement devices. By using cold-atom interferometry, which measures the relative acceleration and rotation of a cloud of atoms stored within a sensor, extremely accurate inertial measurement devices could operate for long periods without needing external data to determine time and position. ANS also seeks to exploit non-navigational electromagnetic signals — including commercial satellite, radio and television signals and even lightning strikes — to provide additional points of reference for PNT.
Microtechnology for Positioning, Navigation, and Timing (Micro-PNT) leverages extreme miniaturization made possible by DARPA-developed micro-electromechanical systems (MEMS) technology. These include precise chip-scale gyroscopes, clocks, and complete integrated timing and inertial measurement devices. DARPA researchers have fabricated a prototype with three gyroscopes, three accelerometers and a highly accurate master clock on a chip that fits easily on the face of a penny.
Quantum-Assisted Sensing and Readout (QuASAR) intends to make the world’s most accurate atomic clocks — which currently reside in laboratories — both robust and portable. QuASAR researchers have developed optical atomic clocks in laboratories with a timing error of less than 1 second in 5 billion years. Making clocks this accurate and portable could improve upon existing military systems such as GPS, and potentially enable entirely new radar, LIDAR, and metrology applications.
The Program in Ultrafast Laser Science and Engineering (PULSE) applies the latest in pulsed laser technology to significantly improve the precision and size of atomic clocks and microwave sources, enabling more accurate time and frequency synchronization over large distances. It could enable global distribution of time precise enough to take advantage of the world’s most accurate optical atomic clocks.
What if computer screens had glasses instead of the people staring at the monitors? That concept is not too far afield from technology being developed by UC Berkeley computer and vision scientists.
The researchers are developing computer algorithms to compensate for an individual’s visual impairment, and creating vision-correcting displays that enable users to see text and images clearly without wearing eyeglasses or contact lenses. The technology could potentially help hundreds of millions of people who currently need corrective lenses to use their smartphones, tablets and computers. One common problem, for example, is presbyopia, a type of farsightedness in which the ability to focus on nearby objects is gradually diminished as the aging eyes’ lenses lose elasticity.
More importantly, the displays could one day aid people with more complex visual problems, known as high order aberrations, which cannot be corrected by eyeglasses, said Brian Barsky, UC Berkeley professor of computer science and vision science, and affiliate professor of optometry.
“We now live in a world where displays are ubiquitous, and being able to interact with displays is taken for granted,” said Barsky, who is leading this project. “People with higher order aberrations often have irregularities in the shape of the cornea, and this irregular shape makes it very difficult to have a contact lens that will fit. In some cases, this can be a barrier to holding certain jobs because many workers need to look at a screen as part of their work. This research could transform their lives, and I am passionate about that potential.”
“The significance of this project is that, instead of relying on optics to correct your vision, we use computation,” said lead author Fu-Chung Huang, who worked on this project as part of his computer science Ph.D. dissertation at UC Berkeley under the supervision of Barsky and Austin Roorda, professor of vision science and optometry. “This is a very different class of correction, and it is non-intrusive.”
The algorithm, which was developed at UC Berkeley, works by adjusting the intensity of each direction of light that emanates from a single pixel in an image based upon a user’s specific visual impairment. In a process called deconvolution, the light passes through the pinhole array in such a way that the user will perceive a sharp image.
A common acrylic polymer used in biomedical applications and as a substitute for glass has been given the ability to completely self-heal underwater by US researchers. The method, which takes inspiration from the self-healing abilities of adhesive proteins secreted by mussels, could allow for longer lasting biomedical implants. Temporary hydrogen bonding network stitches damage as the material fuses together.
'Polymer self-healing research is about 10 years old now and many different strategies have been developed,' says Herbert Waite, who conducted the work with colleagues at the University of California, Santa Barbara. 'None, however, address the need for healing in a wet medium – a critical omission as all biomaterials function, and fail, in wet environments.'
The idea of mimicking the biological self-healing ability of mussel adhesive proteins is notnew, and previous attempts have involved polymer networks functionalised with catechols – synthetic water-soluble organic molecules that mimic mussel adhesive proteins – and metal-ion mediated bonding. However, how mussel adhesive proteins self-heal remains poorly understood, which has limited attempts to synthesise catechols that accurately mimic biological self-healing underwater.
Now, Waite and colleagues have discovered a new aspect of catechols after they were simply 'goofing around' in the lab and found a new way to modify the surface of poly(methyl methacrylate), or PMMA, with catechols. This led them to explore the material's properties and discover that hydrogen bonding enables the polymer to self-heal underwater after being damaged. 'Usually, catechols in wet adhesives are associated with covalent or coordination mediated cross-linking. Our results argue that hydrogen bonding can also be critical, especially as an initiator of healing,' he says.
The healing process begins because catechols provide multidentate hydrogen-bonding faces that trigger a network of hydrogen bonds to fix any damage – the interaction is strong enough to resist interference by water but reversible. Acting a bit like dissolvable stitches, hydrogen bonding between the catechols appears to stitch the damaged area, which allows the underlying polymer to fuse back together. After about 20 minutes, the hydrogen bonded catechols mysteriously disappear leaving the original site of damage completely healed. 'We don't know where the hydrogen bonded catechols go,’ Waite says. ‘Possibly back to the surface, dispersed within the bulk polymer, or some other possibility.'
Phillip Messersmith, a biomaterials expert at the University of California, Berkeley, US, says that this is ‘really creative work’. '[This] reveals a new dimension of catechols, which in this case mediate interfacial self-healing through the formation of hydrogen bonds between surfaces, and which are ultimately augmented or replaced by other types of adhesive interactions.'
Does the Milky Way look fat in this picture? Has Andromeda been taking skinny selfies? Using a new, more accurate method for measuring the mass of galaxies, and international group of researchers has shown that the Milky Way has only half the Mass of the Andromeda Galaxy.
In previous studies, researchers were only able to estimate the mass of the Milky Way and Andromeda based on observations made using their smaller satellite dwarf galaxies. In the new study, researchers culled previously published data that contained information about the distances between the Milky Way, Andromeda and other close-by galaxies -- including those that weren't satellites -- that reside in and right outside an area referred to as the Local Group.
Galaxies in the Local Group are bound together by their collective gravity. As a result, while most galaxies, including those on the outskirts of the Local Group, are moving farther apart due to expansion, the galaxies in the Local Group are moving closer together because of gravity. For the first time, researchers were able to combine the available information about gravity and expansion to complete precise calculations of the masses of both the Milky Way and Andromeda.
"Historically, estimations of the Milky Way's mass have been all over the map," said Walker, an assistant professor of physics at Carnegie Mellon. "By studying two massive galaxies that are close to each other and the galaxies that surround them, we can take what we know about gravity and pair that with what we know about expansion to get an accurate account of the mass contained in each galaxy. This is the first time we've been able to measure these two things simultaneously."
By studying both the galaxies in and immediately outside the Local Group, Walker was able to pinpoint the group's center. The researchers then calculated the mass of both the ordinary, visible matter and the invisible dark matter throughout both galaxies based on each galaxy's present location within the Local Group. Andromeda had twice as much mass as the Milky Way, and in both galaxies 90 percent of the mass was made up of dark matter.
The study was supported by the UK's Science and Technology Facilities Council and led by Jorge Peñarrubia of the University of Edinburgh's School of Physics and Astronomy. Co-authors include Yin-Zhe Ma of the University of British Columbia and Alan McConnachie of the NRC Herzberg Institute of Astrophysics.
Invertebrate numbers have decreased by 45% on average over a 35 year period in which the human population doubled, reports a study on the impact of humans on declining animal numbers.
This decline matters because of the enormous benefits invertebrates such as insects, spiders, crustaceans, slugs and worms bring to our day-to-day lives, including pollination and pest control for crops, decomposition for nutrient cycling, water filtration and human health.
The study, published in Science and led by UCL, Stanford and UCSB, focused on the demise of invertebrates in particular, as large vertebrates have been extensively studied. They found similar widespread changes in both, with an on-going decline in invertebrates surprising scientists, as they had previously been viewed as nature’s survivors.
The decrease in invertebrate numbers is due to two main factors – habitat loss and climate disruption on a global scale. In the UK alone, scientists noted the areas inhabited by common insects such as beetles, butterflies, bees and wasps saw a 30-60% decline over the last 40 years.
Scientists believe there is a growing understanding of how ecosystems are changing but to tackle these issues, better predictions of the impact of changes are needed together with effective policies to reverse the losses currently seen. Using this approach, conservation of species can be prioritized with the benefit of protecting processes that serve human needs, and successful campaigns scaled-up to effect a positive change globally.
The phenomenon is named after the curious feline in Alice in Wonderland, who vanishes leaving only its grin. Researchers took a beam of neutrons and separated them from their magnetic moment, like passengers and their baggage at airport security. They describe their feat in Nature Communications.
The same separation trick could in principle be performed with any property of any quantum object, say researchers from Vienna University of Technology. Their technique could have a useful application in metrology - helping to filter out disturbances during high-precision measurements of quantum systems.
The idea of a "quantum Cheshire Cat" was first proposed in 2010 by Dr Jeff Tollaksen from Chapman University, a co-author on this latest paper. In the world familiar to us, an object and its properties are always bound together. A rotating ball, for instance, cannot become separated from its spin.
The cat (the neutron) goes via the upper beam path, while its grin (the magnetic moment) goes via the lower. But quantum theory predicts that a particle (such as a photon or neutron) can become physically separated from one of its properties - such as its polarisation or its magnetic moment.
"We find the cat in one place, and its grin in another," as the researchers once put it. The feline analogy is a nod to Schrodinger's Cat - the infamous thought experiment in which a cat in a box is both alive and dead simultaneously - illustrating a quantum phenomenon known as superposition.
To prove that the Cheshire Cat is not just a cute theory, the researchers used an experimental set-up known as an interferometer, at the Institute Laue-Langevin (ILL) in Grenoble, France.
A neutron beam was passed through a silicon crystal, sending it down two different paths - like passengers and their luggage at airport security.
By applying filters and a technique known as "post-selection", they were able to detect the physical separation of the neutrons from their magnetic moment - as measured by the direction of their spin.
"The system behaves as if the neutrons go through one beam path, while their magnetic moment travels along the other," the researchers reported.
Highly purified crystals that split light with uncanny precision are key parts of high-powered lenses, specialized optics and, potentially, computers that manipulate light instead of electricity. But producing these crystals by current techniques, such as etching them with a precise beam of electrons, is often extremely difficult and expensive.
Now, researchers at Princeton and Columbia universities have proposed a new method that could allow scientists to customize and grow these specialized materials, known asphotonic crystals, with relative ease.
"Our results point to a previously unexplored path for making defect-free crystals using inexpensive ingredients," said Athanassios Panagiotopoulos, the Susan Dod Brown Professor of Chemical and Biological Engineering and one of the paper's authors. "Current methods for making such systems rely on using difficult-to-synthesize particles with narrowly tailored directional interactions."
Scientists using mission data from NASA's Cassini spacecraft have identified 101 distinct geysers erupting on Saturn's icy moon Enceladus.
This graphic shows a 3-D model of 98 geysers whose source locations and tilts were found in a Cassini imaging survey of Enceladus' south polar terrain by the method of triangulation. While some jets are strongly tilted, it is clear the jets on average lie in four distinct "planes" that are normal to the surface at their source location.
Dotted vectors indicate five jets whose sources were determined from images acquired too closely in time to determine tilts accurately. Consequently their 3-D configuration has a large uncertainty associated with it. Two geysers, indicated by crosses in PIA17188, have no tilt determinations at all and are not shown here.
A movie showing a 360-degree view of this model is also presented here. The still graphic and the movie illustrate some of the findings reported in a paper by Porco, DiNino, and Nimmo, and published in the online version of the Astronomical Journal in July 2014: http://dx.doi.org/10.1088/0004-6256/148/3/46. .
Post-equinox images like this, clearly showing the different projected locations of the intersection between the shadow and the curtain of jets from each fracture, were useful for scientists in checking the triangulated positions of the geysers, as described in a paper by Porco, DiNino, and Nimmo, and published in the online version of the Astronomical Journal in July 2014: http://dx.doi.org/10.1088/0004-6256/148/3/45.
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colorado.
Babies can learn what to fear in the first days of life just by smelling the odor of their distressed mothers, new research suggests. And not just "natural" fears: If a mother experienced something before pregnancy that made her fear something specific, her baby will quickly learn to fear it too -- through the odor she gives off when she feels fear.
In the first direct observation of this kind of fear transmission, a team of University of Michigan Medical School and New York University studied mother rats who had learned to fear the smell of peppermint -- and showed how they "taught" this fear to their babies in their first days of life through their alarm odor released during distress.
In a new paper in the Proceedings of the National Academy of Sciences, the team reports how they pinpointed the specific area of the brain where this fear transmission takes root in the earliest days of life.
Their findings in animals may help explain a phenomenon that has puzzled mental health experts for generations: how a mother's traumatic experience can affect her children in profound ways, even when it happened long before they were born.
The researchers also hope their work will lead to better understanding of why not all children of traumatized mothers, or of mothers with major phobias, other anxiety disorders or major depression, experience the same effects.
"During the early days of an infant rat's life, they are immune to learning information about environmental dangers. But if their mother is the source of threat information, we have shown they can learn from her and produce lasting memories," says Jacek Debiec, M.D., Ph.D., the U-M psychiatrist and neuroscientist who led the research.
"Our research demonstrates that infants can learn from maternal expression of fear, very early in life," he adds. "Before they can even make their own experiences, they basically acquire their mothers' experiences. Most importantly, these maternally-transmitted memories are long-lived, whereas other types of infant learning, if not repeated, rapidly perish."
Influenza imposes a heavy annual public health burden, and lies historically at the heart of a number of global pandemics that killed tens of millions. To overcome the challenges of manufacturing enough vaccines such that we may stave off the next epidemic, medical researchers are searching for ways to strengthen or extend the power of existing and stockpiled vaccines. Now a team of scientists in Boston has just developed a new method of using laser light to stimulate and enhance the immune response to a vaccine by a remarkable 4 to 7-fold against disease agents. Such treatments that assist vaccines but are not vaccines themselves are known as adjuvants.
Interestingly, the improved 4 to 7-fold laser adjuvant could not be matched even when compared against increasing the vaccine dosage 10-fold. Efficacy of the vaccine was measured by the level of influenza-specific antibodies generated in an inoculated person. The new method improves on an existing adjuvant hampered by harmful side effects which thus far has prevented its usage broadly. Although the results were obtained in the context of two animal models, adult and aged mice, as well as pigs, its fairly general immunological basis is expected to translate to humans.
Before inoculation, the injection site is exposed to laser light for a short time. The light does not perforate the outer layers of the skin, but rather injures the dermis. Because of the way the laser light is arranged, this creates a number of “microthermal zones.” In each zone, dermal cells that are damaged stimulate inflammation, signaling danger to the immune system, which in turn attracts antigen-presenting cells (APCs) to the damaged area. APCs are cells that occur naturally in the body that bind antigens of harmful disease agents so as to prepare the rest of the immune system to recognize and neutralize the threat.
The damaged area is so small such that that self-healing occurs within 72 hours. The inspiration for the adjuvant comes from a type of skin treatment used in cosmetic dermatology. In the cosmetic context, the laser light is used to stimulate lightly skin with aged appearance. Post-damage, epithelial cells quickly grow to surround the microthermal zone to give rise to more youthful looking skin. The same class of non-ablative lasers were used in this study.
Myorobotics at the Technical University of Munich, takes us on a fascinating journey on how an adorable humanoid robot with muscles, called Roboy, is born in 9 months, and sheds light on the future of robotics, and what kind of future it might bring us. Being fascinated by the complexity and beauty of everything, Rafael Hostettler always had a hard time to choose. That’s why he has an MSc. in Computational Science from ETH Zurich, where he learnt to simulate just about everything on computers, so he didn’t have to make a decision. Now he’s building robots that imitate the building principles of the human musculoskeletal system and travels the world with Roboy. The 3D printed robot boy that plays in a theatre, goes to school and captivates the audience with his fascinating stories.
Schematic of micro- and nanopropellers in hyaluronan gels. The polymeric mesh structure blocks the larger micropropellers (top left), but smaller propellers.
Israeli and German researchers have created a nanoscale screw-shaped propeller that can move in a gel-like fluid, mimicking the environment inside a living organism, as described in a paper published in the June 2014 issue of ACS Nano.
The filament that makes up the propeller, made of silica and nickel, is only 70 nanometers in diameter; the entire propeller is 400 nanometers long, small enough that their motion can be affected by Brownian motion of nearby molecules.
To test if the propellers could move through living organisms, they used hyaluronan, a material that occurs throughout the human body, including the synovial fluids in joints and the vitreous humor in your eyeball.
The hyaluronan gel contains a mesh of long proteins called polymers; the polymers are large enough to prevent micron-sized (millionths of a meter) propellers from moving much at all. But the openings are large enough for nanometer-sized objects to pass through. The scientists were able to control the motion of the propellers using a relatively weak rotating magnetic field.
“One can now think about targeted applications, for instance, in the eye, where they may be moved to a precise location at the retina,” says Peer Fischer, a member of the research team and head of the Micro, Nano, and Molecular Systems Lab at the Max Planck Institute for Intelligent Systems.
Scientists could also attach “active molecules” to the tips of the propellers, or use the propellers to deliver tiny targeted doses of radiation.
A 53-year-old Swede can take credit for 2.7 million articles on Wikipedia, but some "purists" complain about his method.
Sverker Johansson could be the most prolific author you've never heard of. Volunteering his time over the past seven years publishing to Wikipedia, the 53-year-old Swede can take credit for 2.7 million articles, or 8.5% of the entire collection, according to Wikimedia analytics, which measures the site's traffic. His stats far outpace any other user, the group says.
He has been particularly prolific cataloging obscure animal species, including butterflies and beetles, and is proud of his work highlighting towns in the Philippines. About one-third of his entries are uploaded to the Swedish language version of Wikipedia, and the rest are composed in two versions of Filipino, one of which is his wife's native tongue. An administrator holding degrees in linguistics, civil engineering, economics and particle physics, he says he has long been interested in "the origin of things, oh, everything."
It isn't uncommon, however, for Wikipedia purists to complain about his method. That is because the bulk of his entries have been created by a computer software program—known as a bot. Critics say bots crowd out the creativity only humans can generate.
Mr. Johansson's program scrubs databases and other digital sources for information, and then packages it into an article. On a good day, he says his "Lsjbot" creates up to 10,000 new entries.
On Wikipedia, any registered user can create an entry. Mr. Johansson has to find a reliable database, create a template for a given subject and then launch his bot from his computer. The software program searches for information, then publishes it to Wikipedia.
Bots have long been used to author and edit entries on Wikipedia, and, more recently, an increasingly large amount of the site's new content is written by bots. Their use is regulated by Wikipedia users called the "Bot Approvals Group."
While Mr. Johansson works to achieve consensus approval for his project, he and his bot-loving peers expect to continue facing resistance. "There is a vocal minority who don't like it," he said during a recent speech on his work. Still, he soldiers on.
"I'm doing this to create absolute democracy online," Mr. Johansson said recently while sitting in front of a computer at his office at Sweden's Dalarna University.
Wikipedia, he reckons, should someday be able to tell people everything about everything. His bot, which took him months' worth of programming to create, is a step toward achieving that goal sooner rather than later—even if the entries it creates are bare-boned "stubs" containing basic information.
Achim Raschka is one of the people who would like Mr. Johansson to change course. The 41-year-old German Wikipedia enthusiast can spend days writing an in-depth article about a single type of plant.
"I am against production of bot-generated stubs in general," he said. He is particularly irked by Mr. Johansson's Lsjbot, which prizes quantity over quality and is "not helping the readers and users of Wikipedia."
In the 1960s, Pekka Pyykkö, now at University of Helsinki, Finland, discovered that gold’s colour was the result of relativistic effects. He showed that the lower energy levels of the 6s orbital of gold means that the energy required to excite an electron from the 5d band lies in the visible rather than UV range of light. This means that gold absorbs blue light, while reflecting yellow and red light, and it is this that gives the metal its characteristic hue. If the energies of the two bands were calculated without including relativistic effects, the energy required is much greater. Further calculations have subsequently shown the influence of relativity on the colour and bond lengths of heavy metal compounds, as well as its importance in catalysis. However, the low melting point of mercury could still only be described as ‘probably’ due to relativistic effects.
An international team led by Peter Schwerdtfeger of Massey University Auckland in New Zealand used quantum mechanics to make calculations of the heat capacity of the metal either including or excluding relativistic effects. They showed that if they ignored relativity when making their calculations, the predicted melting point of mercury was 82°C. But if they included relativistic effects their answer closely matched the experimental value of -39°C.
Relativity states that objects get heavier the faster they move. In atoms, the velocity of the innermost electrons is related to the nuclear charge. The larger the nucleus gets the greater the electrostatic attraction and the faster the electrons have to move to avoid falling into it. So, as you go down the periodic table these 1s electrons get faster and faster, and therefore heavier, causing the radius of the atom to shrink. This stabilises some orbitals, which also have a relativistic nature of their own, while destabilising others. This interplay means that for heavy elements like mercury and gold, the outer electrons are stabilised. In mercury’s case, instead of forming bonds between neighbouring mercury atoms, the electrons stay associated with their own nuclei, and weaker interatomic forces such as van der Waals bonds hold the atoms together.
The microbes living in the guts of males and females react differently to diet, even when the diets are identical, according to a study by scientists from The University of Texas at Austin and six other institutions published this week in the journal Nature Communications. These results suggest that therapies designed to improve human health and treat diseases through nutrition might need to be tailored for each sex.
The researchers studied the gut microbes in two species of fish and in mice, and also conducted an in-depth analysis of data that other researchers collected on humans. They found that in fish and humans diet affected the microbiota of males and females differently. In some cases, different species of microbes would dominate, while in others, the diversity of bacteria would be higher in one sex than the other.
These results suggest that any therapies designed to improve human health through diet should take into account whether the patient is male or female.
Only in recent years has science begun to completely appreciate the importance of the human microbiome, which consists of all the bacteria that live in and on people’s bodies. There are hundreds or even thousands of species of microbes in the human digestive system alone, each varying in abundance.
Genetics and diet can affect the variety and number of these microbes in the human gut, which can in turn have a profound influence on human health. Obesity, diabetes, and inflammatory bowel disease have all been linked to low diversity of bacteria in the human gut.
One concept for treating such diseases is to manipulate the microbes within a person’s gut through diet. The idea is gaining in popularity because dietary changes would make for a relatively cheap and simple treatment.
Much has to be learned about which species, or combination of microbial species, is best for human health. In order to accomplish this, research has to illuminate how these microbes react to various combinations of diet, genetics and environment. Unfortunately, to date most such studies only examine one factor at a time and do not take into account how these variables interact.
“Our study asks not just how diet influences the microbiome, but it splits the hosts into males and females and asks, do males show the same diet effects as females?” said Daniel Bolnick, professor in The University of Texas at Austin's College of Natural Sciences and lead author of the study.
The Silk Leaf project uses chloroplasts from real plants suspended in silk proteins to create a hardy vehicle for photosynthesis.
The leaves, created by Royal College of Art student Julian Melchiorri, absorb water and carbon dioxide just like real plants but are made from tough silk proteins that could let them survive space voyages.
Melchiorri explains: "NASA is researching different ways to produce oxygen for long-distance space journeys to let us live in space. This material could allow us to explore space much further than we can now."
The Silk Leaf project was engineered in collaboration with Tufts University silk lab, which helped Melchiorri extract chloroplasts from real leaves and suspend them in a silk matrix.
"The material is extracted directly from the fibres of silk," explains Melchiorri. "This material has an amazing property of stabilising molecules. I extracted chloroplasts from plant cells and placed them inside this silk protein. As an outcome I have the first photosynthetic material that is living and breathing as a leaf does."
Chloroplasts are the parts of plant cells that conduct photosynthesis, using the energy of the sun to turn carbon dioxide and water to create glucose and oxygen.
Melchiorri’s creations are currently more conceptual than practical (the efficiency of the photosynthesis process hasn’t been tested for one) but he hopes they could be used in all manner of futuristic architectural projects, perhaps even deploying giant leaves as air filters, hanging them on the exterior of buildings to absorb CO2 and channel fresh air inside.
Astronomers have long known that interstellar molecules containing carbon atoms exist and that by their nature they will absorb light shining on them from stars and other luminous bodies. Because of this, a number of scientists have previously proposed that some type of interstellar molecules are the source of diffuse interstellar bands -- the hundreds of dark absorption lines seen in color spectrograms taken from Earth. In showing nothing, these dark bands reveal everything. The missing colors correspond to photons of given wavelengths that were absorbed as they travelled through the vast reaches of space before reaching us. More than that, if these photons were filtered by falling on space-based molecules, the wavelengths reveal the exact energies it took to excite the electronic structures of those absorbing molecules in a defined way.
Over the vast, empty reaches of interstellar space, these countless small molecules tumble quietly though the cold vacuum. The interstellar medium is the matter that exists in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, dust, and cosmic rays. Forged in the fusion furnaces of ancient stars and ejected into space when those stars exploded, these lonely molecules account for a significant amount of all the carbon, hydrogen, silicon and other atoms in the universe. In fact, some 20 percent of all the carbon in the universe is thought to exist as some form of interstellar molecule.
Many astronomers hypothesize that these interstellar molecules are also responsible for an observed phenomenon on Earth known as the "diffuse interstellar bands," spectrographic proof that something out there in the universe is absorbing certain distinct colors of light from stars before it reaches the Earth. But since we don't know the exact chemical composition and atomic arrangements of these mysterious molecules, it remains unproven whether they are, in fact, responsible for the diffuse interstellar bands.
Now in a paper appearing this week in The Journal of Chemical Physics, a group of scientists led by researchers at the Harvard-Smithsonian Center for Astrophysics has offered a tantalizing new possibility: these mysterious molecules may be silicon-capped hydrocarbons like SiC3H, SiC4H and SiC5H, and they present data and theoretical arguments to back that hypothesis. At the same time, the group cautions that history has shown that while many possibilities have been proposed as the source of diffuse interstellar bands, none has been proven definitively.
Armed with that information, scientists here on Earth should be able to use spectroscopy to identify those interstellar molecules -- by demonstrating which molecules in the laboratory have the same absorptive "fingerprints." But despite decades of effort, the identity of the molecules that account for the diffuse interstellar bands remains a mystery. Nobody has been able to reproduce the exact same absorption spectra in laboratories here on Earth.
"Not a single one has been definitively assigned to a specific molecule," said Neil Reilly, a former postdoctoral fellow at Harvard-Smithsonian Center for Astrophysics and a co-author of the new paper. Now Reilly, McCarthy and their colleagues are pointing to an unusual set of molecules — silicon-terminated carbon chain radicals — as a possible source of these mysterious bands.
As they report in their new paper, the team first created silicon-containing carbon chains SiC3H, SiC4H and SiC5H in the laboratory using a jet-cooled silane-acetylene discharge. They then analyzed their spectra and carried out theoretical calculations to predict that longer chains in this family might account for some portion of the diffuse interstellar bands.
The ESA has tested a novel system that may allow the agency to safely land rovers on Mars using a quadcopter-like dropship. A fully automated, proof of concept Skycrane prototype was created over the course of eight months under the ESA's StarTiger program, with the system's hardware largely derived from commercially available quadcopter components.
The primary challenge for the Dropter project development team revolved around creating a system that could successfully detect and navigate hazardous terrain without the aide of real-time human input. This is a vital feature for any potential rover delivery system, as it is impossible to create a directly controllable sky crane due to the distance between the operator and the vehicle that creates a time lag between command and execution.
Therefore the new rover delivery method had to be designed around an autonomous navigation system. Initially the dropship navigates to the pre determined deployment zone using GPS and inertia control. Once in the vicinity of the target zone, the lander switches to vision-based navigation, utilizing laser ranging and barometers to allow it to detect a safe, flat area upon which to set down its precious cargo.
Once such a site is identified, the lander drops to a height of 10 m (33 ft) above the surface and lowers the rover with the use of a bridle, gradually descending until the rover gently touches down on the planet's surface.
The culmination of eight months of development took place at Airbus’s Trauen site, located in northern Germany, where the concept dropship was put through its paces in a 40 m (131 ft) by 40 m (131 ft) recreation of the Martian surface. During the test, the lander managed to successfully use its navigation systems to safely transport a mock rover to the chosen target zone, whereupon the delivery vehicle assessed and selected a flat, safe landing site, and deployed the rover using the 5 m (16 ft) bridle.
Now, with the concept a proven success, the agency and its partners can focus on further developing the dropship for heavier, more realistic payloads.
The video below displays footage of the prototype dropship during the test at Airbus’s Trauen facility.
Communities are groups that are densely connected among their members, and sparsely connected with the rest of the network. Community structure can reveal abundant hidden information about complex networks that is not easy to detect by simple observation. There are many large-scale complex networks (systems) in the real world whose structure is not fully understood. A great deal of research has been carried out to uncover the structures of these real world networks, to improve the ability to manage, maintain, renovate and control them. With the help of varied approaches, it is possible to shed light on the general structure of these networks, and further understand their function.
Network science methods have been used in various settings [1, 2] including social,[3, 4] information, transportation, energy, ecological, disease,  and biological networks. [10, 11, 12,13] In most of these cases we can find clear community structures, which are usually associated with specific functions. However, to date, most detection methods have limitations, and there is still a lot of room to develop more general approaches.
At present, most methods focus on the detection of node community. One popular approach is based on the optimization of the modularity Q [14, 15, 52, 56] of a sub-network.
Some methods [13, 14,29, 34, 38, 39, 40] force every node to be assigned to a single community. This assumption doesn't always reflect real world networks, where several overlapping communities can co-exist. For example, in social networks, a person may have family relationship circles, job circles, friend circles, social circles, hobby circles and so on. Algorithms that can discover overlapping communities [16, 17, 18, 19, 20, 21, 22, 23] have been developed, and recently, methods to detect link communities [20, 24, 25] have been presented.
The concept of a link community is useful for discovering overlapping communities, as edges are more likely to have unique identities than nodes, which instead tend to have multiple identities. In addition, statistical,  information-theoretic [35, 48, 53] and synchronization and dynamical clustering approaches [49, 50, 58, 59, 60] have also been developed to detect communities.
The interactive map produced by researchers from Oxford University and UCL (University College London), details the histories of genetic mixing between each of the 95 populations across Europe, Africa, Asia and South America spanning the last four millennia.
The study, published this week in Science, simultaneously identifies, dates and characterises genetic mixing between populations. To do this, the researchers developed sophisticated statistical methods to analyse the DNA of 1490 individuals in 95 populations around the world. The work was chiefly funded by the Wellcome Trust and Royal Society.
'DNA really has the power to tell stories and uncover details of humanity's past,' said Dr Simon Myers of Oxford University's Department of Statistics and Wellcome Trust Centre for Human Genetics, co-senior author of the study.
'Because our approach uses only genetic data, it provides information independent from other sources. Many of our genetic observations match historical events, and we also see evidence of previously unrecorded genetic mixing. For example, the DNA of the Tu people in modern China suggests that in around 1200CE, Europeans similar to modern Greeks mixed with an otherwise Chinese-like population. Plausibly, the source of this European-like DNA might be merchants travelling the nearby Silk Road.'
The powerful technique, christened 'Globetrotter', provides insight into past events such as the genetic legacy of the Mongol Empire. Historical records suggest that the Hazara people of Pakistan are partially descended from Mongol warriors, and this study found clear evidence of Mongol DNA entering the population during the period of the Mongol Empire. Six other populations, from as far west as Turkey, showed similar evidence of genetic mixing with Mongols around the same time.
'What amazes me most is simply how well our technique works,' said Dr Garrett Hellenthal of the UCL Genetics Institute, lead author of the study. 'Although individual mutations carry only weak signals about where a person is from, by adding information across the whole genome we can reconstruct these mixing events. Sometimes individuals sampled from nearby regions can have surprisingly different sources of mixing.
'For example, we identify distinct events happening at different times among groups sampled within Pakistan, with some inheriting DNA from sub-Saharan Africa, perhaps related to the Arab Slave Trade, others from East Asia, and yet another from ancient Europe. Nearly all our populations show mixing events, so they are very common throughout recent history and often involve people migrating over large distances.'
The team used genome data for all 1490 individuals to identify 'chunks' of DNA that were shared between individuals from different populations. Populations sharing more ancestry share more chunks, and individual chunks give clues about the underlying ancestry along chromosomes.
'Each population has a particular genetic 'palette', said Dr Daniel Falush of the Max Planck Institute for Evolutionary Anthropology in Leipzig, co-senior author of the study.
'If you were to paint the genomes of people in modern-day Maya, for example, you would use a mixed palette with colours from Spanish-like, West African and Native American DNA. This mix dates back to around 1670CE, consistent with historical accounts describing Spanish and West African people entering the Americas around that time. Though we can't directly sample DNA from the groups that mixed in the past, we can capture much of the DNA of these original groups as persisting, within a mixed palette of modern-day groups. This is a very exciting development.'
A map captures the Martian craters, valleys and peaks in stunning detail and offers ideas on where the rovers of the future might land.
What really lies across the surface of Mars? Rovers have scurried about the red planet for years, drilling, scooping and analyzing for signs of life, past or present. But to really understand the Martian landscape, scientists need to look at the entire surface. What they have needed is a global geologic map. The red planet is long overdue for a new one. The last major effort in Martian cartography was published in 1987, scraped together from the early Viking probes’ scant images and datasets. Since then, four additional orbiters with superior imaging capabilities have journeyed into Martian orbit, collected data and transmitted their findings back to Earth.
Now, scientists at the United States Geological Survey have used that data to create an updated map of the entire Martian surface. The new map shows that ancient rock — dating back billions of years ago, when Mars’s environmental conditions might have closely resembled Earth’s— exists in many more locations than previously thought. Because the map highlights the location of the oldest rocks on Mars, it could help future missions chart a course for these areas.
“We are disproportionately interested in the early part of Martian history,” said David Beaty, the chief scientist for the Mars Exploration Directorate at the Jet Propulsion Laboratory in Pasadena, Calif., who was not involved in the research. “It was during that period that more water would have been around, which is one of the key aspects of the origin of life.”
The project, funded by NASA, was not simply a compilation of photographs from Martian orbit. Recent probes, such as the Mars Global Surveyorlaunched in 1996, were outfitted with advanced topographical instruments that helped cartographers pinpoint the subtler features of the Martian landscape.
Flood. Drought. Heat waves. Ice melt. The impact of a warming world is being manifested in a variety of ways, and we can see it from space. Browse through our gallery of pictures taken by NASA satellites looking down at planet Earth.
Less than a year after a devastating 2003 heat wave killed over 37,000 people across Europe, another heat wave struck the region. On July 1, 2004, this image from NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) recorded land surface temperatures of 138°F (59°C) in Spain. In this false-color image, red represents the warmest temperatures, yellow is intermediate, and light and dark blue are progressively cooler. Air temperatures in both countries soared over 104°F (40°C). Three days after this image was taken, Spain set a new air temperature record for the nation: 117°F (47°C). Climate models predict more extreme weather events, including heat waves, in the coming decades due to man-made climate change.
Found at the intersection of four different countries in West Africa, Lake Chad was once one of the African continent's largest bodies of fresh water, close in surface area to North America's Lake Erie. But today it is a ghost of its former self, reduced to only about 1/20th its former size in just four decades, thanks to prolonged drought and human demand for water.
A warming world also makes heavily populated coastal areas more vulnerable to flooding: higher global temperatures produce warmer seawater, which expands and causes a rise in sea level. Approximately 400 million people live within 20 meters (0.01 miles) of sea level and 20 km (12 miles) of a coast; modest increases in sea level could displace millions of people.
Wildfire activity in the western U.S. has increased markedly since the mid-1980s, with more frequent large fires and longer fire seasons. Climate models predict increased wildfire risk across many areas of the globe in coming decades.
New research by theorists at the Harvard-Smithsonian Center for Astrophysics(CfA) shows that we could spot the fingerprints of certain pollutants under ideal conditions. This would offer a new approach in the search for extraterrestrial intelligence (SETI).
“We consider industrial pollution as a sign of intelligent life, but perhaps civilizations more advanced than us, with their own SETI programs, will consider pollution as a sign of unintelligent life since it’s not smart to contaminate your own air,” said Harvard student and lead author Henry Lin.
“People often refer to ETs as ‘little green men,’ but the ETs detectable by this method should not be labeled ‘green’ since they are environmentally unfriendly,” added co-author Avi Loeb, Harvard’s Frank B. Baird Jr. Professor of Science.
The team, which also includes Smithsonian scientist Gonzalo Gonzalez Abad, finds that the upcoming James Webb Space Telescope (JWST) should be able to detect two kinds of chlorofluorocarbons (CFCs) — ozone-destroying chemicals used in solvents and aerosols. They calculated that JWST could tease out the signal of CFCs if atmospheric levels were 10 times those on Earth. A particularly advanced civilization might intentionally pollute the atmosphere to high levels and globally warm a planet that is otherwise too cold for life.
There is one big caveat to this work. JWST can only detect pollutants on an Earth-like planet circling a white dwarf star, which is what remains when a star like our sun dies. That scenario would maximize the atmospheric signal. Finding pollution on an Earth-like planet orbiting a sun-like star would require an instrument beyond JWST — a next-next-generation telescope.
The team notes that a white dwarf might be a better place to look for life than previously thought, since recent observations found planets in similar environments. Those planets could have survived the bloating of a dying star during its red giant phase, or have formed from the material shed during the star’s death throes.