Their findings are reported in the journal Nature Nanotechnology.

The U of T researchers, led by Professors Shana Kelley and Ted Sargent, report the construction of what they term "artificial molecules."

"Nanotechnologists have for many years been captivated by quantum dots -- particles of semiconductor that can absorb and emit light efficiently, and at custom-chosen wavelengths," explained co-author Kelley, a Professor at the Leslie Dan Faculty of Pharmacy, the Department of Biochemistry in the Faculty of Medicine, and the Department of Chemistry in the Faculty of Arts & Science. "What the community has lacked -- until now -- is a strategy to build higher-order structures, or complexes, out of multiple different types of quantum dots. This discovery fills that gap."

The team combined its expertise in DNA and in semiconductors to invent a generalized strategy to bind certain classes of nanoparticles to one another.

Illustration of a nanoantenna complex. Right: Actual image of the complex as visualized by transmission electron microscopy. (Credit: Image courtesy of University of Toronto Faculty of Applied Science & Engineering)

"The credit for this remarkable result actually goes to DNA: its high degree of specificity -- its willingness to bind only to a complementary sequence -- enabled us to build rationally-engineered, designer structures out of nanomaterials," said Sargent, a Professor in The Edward S. Rogers Sr. Department of Electrical & Computer Engineering at the University of Toronto, who is also the Canada Research Chair in Nanotechnology. "The amazing thing is that our antennas built themselves -- we coated different classes of nanoparticles with selected sequences of DNA, combined the different families in one beaker, and nature took its course. The result is a beautiful new set of self-assembled materials with exciting properties."

Traditional antennas increase the amount of an electromagnetic wave -- such as a radio frequency -- that is absorbed, and then funnel that energy to a circuit. The U of T nanoantennas instead increased the amount of light that is absorbed and funneled it to a single site within their molecule-like complexes. This concept is already used in nature in light harvesting antennas, constituents of leaves that make photosynthesis efficient. "Like the antennas in radios and mobile phones, our complexes captured dispersed energy and concentrated it to a desired location. Like the light harvesting antennas in the leaves of a tree, our complexes do so using wavelengths found in sunlight," explained Sargent.

"Professors Kelley and Sargent have invented a novel class of materials with entirely new properties. Their insight and innovative research demonstrates why the University of Toronto leads in the field of nanotechnology," said Professor Henry Mann, Dean of the Leslie Dan Faculty of Pharmacy.

"This is a terrific piece of work that demonstrates our growing ability to assemble precise structures, to tailor their properties, and to build in the capability to control these properties using external stimuli," noted Paul S. Weiss, Fred Kavli Chair in NanoSystems Sciences at UCLA and Director of the California NanoSystems Institute.

Kelley explained that the concept published in the Nature Nanotechnology paper is a broad one that goes beyond light antennas alone.

"What this work shows is that our capacity to manipulate materials at the nanoscale is limited only by human imagination. If semiconductor quantum dots are artificial atoms, then we have rationally synthesized artificial molecules from these versatile building blocks."

Also contributing to the paper were researchers Sjoerd Hoogland and Armin Fischer of The Edward S. Rogers Sr. Department of Electrical & Computer Engineering, and Grigory Tikhomirov and P. E. Lee of the Leslie Dan Faculty of Pharmacy.

The publication was based in part on work supported by the Ontario Research Fund Research Excellence Program, the Natural Sciences and Engineering Research Council of Canada (NSERC), Canada Research Chairs program and the National Institutes of Health (NIH).

Source: University of Toronto

Computers are great at treating words as data: Word-processing programs let you rearrange and format text however you like, and search engines can quickly find a word anywhere on the Web. But what would it mean for a computer to actually understand the meaning of a sentence written in ordinary English -- or French, or Urdu, or Mandarin?

One test might be whether the computer could analyze and follow a set of instructions for an unfamiliar task. And indeed, in the last few years, researchers at MIT's Computer Science and Artificial Intelligence Lab have begun designing machine-learning systems that do exactly that, with surprisingly good results.

In 2009, at the annual meeting of the Association for Computational Linguistics (ACL), researchers in the lab of Regina Barzilay, associate professor of computer science and electrical engineering, took the best-paper award for a system that generated scripts for installing a piece of software on a Windows computer by reviewing instructions posted on Microsoft's help site. At this year's ACL meeting, Barzilay, her graduate student S. R. K. Branavan and David Silver of University College London applied a similar approach to a more complicated problem: learning to play "Civilization," a computer game in which the player guides the development of a city into an empire across centuries of human history. When the researchers augmented a machine-learning system so that it could use a player's manual to guide the development of a game-playing strategy, its rate of victory jumped from 46 percent to 79 percent.

Starting from scratch

"Games are used as a test bed for artificial-intelligence techniques simply because of their complexity," says Branavan, who was first author on both ACL papers. "Every action that you take in the game doesn't have a predetermined outcome, because the game or the opponent can randomly react to what you do. So you need a technique that can handle very complex scenarios that react in potentially random ways."

Moreover, Barzilay says, game manuals have "very open text. They don't tell you how to win. They just give you very general advice and suggestions, and you have to figure out a lot of other things on your own." Relative to an application like the software-installing program, Branavan explains, games are "another step closer to the real world."

The extraordinary thing about Barzilay and Branavan's system is that it begins with virtually no prior knowledge about the task it's intended to perform or the language in which the instructions are written. It has a list of actions it can take, like right-clicks or left-clicks, or moving the cursor; it has access to the information displayed on-screen; and it has some way of gauging its success, like whether the software has been installed or whether it wins the game. But it doesn't know what actions correspond to what words in the instruction set, and it doesn't know what the objects in the game world represent.

So initially, its behavior is almost totally random. But as it takes various actions, different words appear on screen, and it can look for instances of those words in the instruction set. It can also search the surrounding text for associated words, and develop hypotheses about what actions those words correspond to. Hypotheses that consistently lead to good results are given greater credence, while those that consistently lead to bad results are discarded.

Proof of concept

In the case of software installation, the system was able to reproduce 80 percent of the steps that a human reading the same instructions would execute. In the case of the computer game, it won 79 percent of the games it played, while a version that didn't rely on the written instructions won only 46 percent. The researchers also tested a more-sophisticated machine-learning algorithm that eschewed textual input but used additional techniques to improve its performance. Even that algorithm won only 62 percent of its games.

"If you'd asked me beforehand if I thought we could do this yet, I'd have said no," says Eugene Charniak, University Professor of Computer Science at Brown University. "You are building something where you have very little information about the domain, but you get clues from the domain itself."

Charniak points out that when the MIT researchers presented their work at the ACL meeting, some members of the audience argued that more sophisticated machine-learning systems would have performed better than the ones to which the researchers compared their system. But, Charniak adds, "it's not completely clear to me that that's really relevant. Who cares? The important point is that this was able to extract useful information from the manual, and that's what we care about."

Most computer games as complex as "Civilization" include algorithms that allow players to play against the computer, rather than against other people; the games' programmers have to develop the strategies for the computer to follow and write the code that executes them. Barzilay and Branavan say that, in the near term, their system could make that job much easier, automatically creating algorithms that perform better than the hand-designed ones.

But the main purpose of the project, which was supported by the National Science Foundation, was to demonstrate that computer systems that learn the meanings of words through exploratory interaction with their environments are a promising subject for further research. And indeed, Barzilay and her students have begun to adapt their meaning-inferring algorithms to work with robotic systems.

Source: Science Daily

Three-dimensional information on the distribution of elements or phases within materials is critical when dealing with compounds that are anisotropic or heterogeneous in nature. This information is required when modeling properties in materials or for predicting synthetic routes.

A group of scientists in the United States has developed a tomography technique harnessing the characteristics of femtosecond laser ablation to build 3D datasets. This automated technique provides a new way of imaging complex materials in a fraction of the time when compared to existing technologies, such as mechanical or focused ion beam techniques.

Schematic of the instrumentation. Image courtesy of McLean Echlin.

It is well known how tomographic imaging can elucidate problems in medicine, geology, oceanography, and materials science. 2D slices of samples that can be successfully reconstructed into 3D rich datasets may be acquired with a wide variety of techniques that use electrons, neutrons, x-rays, ions, visible light, or acoustic waves. However, this technique is accompanied by many restrictions, in terms of the resolution, quality of data, sample preparation and of course acquisition time. It is also a very skilled and labor intensive procedure.

In this study the scientists, from UC Santa Barbara and the University of Michigan, have succeeded in overcoming many of these obstacles. The newly developed femtosecond laser based technique involves laser ablation followed by optical imaging of the ablated surface, with no subsequent surface preparation required. These steps are repeated for the number of slices required to section a predetermined volume of material.

The ablation event and incoming laser are orthogonal to the plane of the sample surface. Images are captured optically during the sectioning experiment using a high resolution CCD detector. Statistical analysis of the datasets was then carried out.

With this set up the scientists were successfully able to distinguish TiN particles in steel, with a diameter larger than 1 micron. Imaging enhancements, including in situ SEM and the integration of laser induced breakdown spectroscopy, are currently on-going in order to improve the resolution by an order of magnitude.

This new tomography method is ideal for imaging multiphase systems containing phases with similar densities that are inherently difficult to image using other techniques, such as x-ray based measurements.

Many experiments and observations still need to be carried out; for instance, making use of the non-contact mode of laser machining, which will allow materials to be sampled in vacuum, and to take advantage of other analysis techniques such as EBSD and EDS.

Source: Materials Today

DETROIT – In 2005, Jeffrey Martin, Ph.D., professor of kinesiology, health and sport studies in Wayne State University's College of Education, found that children living in underserved communities are less physically active than their higher-income counterparts. Now, in a follow-up study, Martin has found environmental factors that may affect underserved children's physical activity and fitness levels: classmate support, gender and confidence. The study was published in the June 2011 issue of Research Quarterly for Exercise and Sport.

"Underserved children, such as minority children living in low-income households, do not engage in enough physical activity either in or out of school and often lack fitness compared to Caucasian children," said Martin.

To find out why, Martin tested social and physical environmental factors at underserved schools. "Examining the school environment is a particularly important consideration in underserved communities, because often children have limited equipment, and play areas are unsafe or in poor condition," Martin said.

Martin measured social factors, including how much confidence children have in their own abilities, how much confidence they have in seeking support from teachers, how much support they receive from classmates and how conducive to physical activity they perceive their school to be. Participants in the study included African American, Caucasian, Asian American, Arab American, Hispanic American and Bengali middle school children between the ages of 10 and 14.

Confidence in their abilities and classmate support were most predictive of physical activity levels. However, most of the children were neutral about how physically and socially facilitative their school environments were to physical activity, and they did not have particularly strong confidence in their own abilities or in seeking help from teachers.

"Given the importance of peer social support, adult support, personal agency and a supportive environment for physical activity, it is certainly plausible that underserved children's lack of strong beliefs in these areas contributes to their limited physical activity," said Martin.

Confidence in seeking support from teachers was strongly related to physical activity and fitness, and Martin believes teacher support is more critical to underserved children than to children living in communities with higher socioeconomic statuses. "Fifty-seven percent of the underserved children in the state where the study was conducted live with one parent, making it plausible that the influence that teachers of underserved children have is more important relative to the influence they might have on children from two-parent homes," said Martin.

A secondary aim of the study was to determine whether gender played a role in underserved children's physical activity and fitness rates. Boys had higher levels of fitness, participated in more physical activity and reported receiving greater amounts of classmate support than girls did. "These findings suggest that it is important to be cognizant of gender differences in physical activity research," said Martin.

Martin collaborated with Nate McCaughtry, Ph.D., associate professor of pedagogy, kinesiology and physical education, and physical education program coordinator in WSU's College of Education; Sara Flory, doctoral student in WSU's College of Education; Anne Murphy, Ph.D., associate professor of research in WSU's College of Education; and Kimberlydawn Wisdom, M.D., vice president of Community Health Education and Wellness at Henry Ford Health System and Michigan's First Surgeon General.

"We hope our findings add to a body of knowledge that draws attention to the health status of underserved children and ultimately might influence public awareness and policy," said Martin.

Martin is currently continuing research on children in Detroit with an emphasis on their physical activity and nutrition quality.

Source: EurekAlert

While scientists have long had the ability to edit individual genes, it is a slow, expensive and hard to use process. Now researchers at Harvard and MIT have developed technologies, which they liken to the genetic equivalent of the find-and-replace function of a word processing program, that allow them to make large-scale edits to a cell's genome. The researchers say such technology could be used to design cells that build proteins not found in nature, or engineer bacteria that are resistant to any type of viral infection.

DNA consists of long strings of "letters" (A, C, G and T) - or nucleotides - that code for specific amino acids. The genetic code consists of three-letter 'words' called codons, which are formed from a sequence of three nucleotides, such as ACT, CAG. The new technology is possible because all living organisms use the same genetic code to translate those letters into amino acids, which are then strung together into proteins. While most codons specify an amino acid, there are a few that tell the cell when to stop adding amino acids to a protein chain. It was one of these "stop" condons that the researchers targeted in their research.

To make edits to the genome of E. coli, they combined a technique previously unveiled in 2009, called multiplex automated genome engineering (MAGE), with a new technology dubbed conjugative assembly genome engineering (CAGE).

Dubbed an "evolution machine" for its ability to accelerate targeted change in living cells, MAGE locates specific DNA sequences and replaces them with a new sequence as the cell copies its DNA. This allows scientists to precisely control the types of genetic changes that occur in cells as the targets are replaced, while the rest of the genome remains untouched.

The researchers used MAGE to replace the TAG codon with another stop codon, TAA, in living E. coli cells. They chose the TAG codon because, with just 314 occurrences, it is the rarest in the E. coli genome. To make the process more manageable, they first used MAGE to engineer 32 strains of E. coli, each of which has 10 TAG condons replaced.

To combine those strains and eventually end up with one that has all 314 edits, they then developed CAGE, which allows them to precisely control a naturally occurring process called conjugation that bacteria use to exchange genetic material. The CAGE method resembles a playoff bracket, with the researchers inducing the cells to transfer genes containing TAA condons at increasingly larger scales.

After the first round of CAGE, the researchers had 16 strains, each of which had double the number of TAG edits that it started with. Those 16 strains then went into a second round producing eight strains that once again possessed more TAA codons and fewer TAG. And so on, so at the four strains stage, each had about one quester of the possible TAG substitutions.

Eager to share their findings, the researchers published their results at the semi-final round, but say they believe they are now on track to produce a single combined strain with all 314 of the substitutions.

Because the alterations were done in living cells, the researchers have been able to monitor any potential harmful effects as they appear and current results suggested that the final four strains were healthy, and can survive and reproduce.

The researchers are confident that they will create a single strain in which all TAG codons are eliminated, after which they plan to delete the cell machinery that reads the TAG condon to free it up for a completely new purpose, such as encoding a novel amino acid.

In addition to adding functionality to a cell by encoding for useful new amino acids, George Church, professor of genetics at Harvard Medical School, says the technology could also be used to introduce safeguards that prevent cross-contamination between modified organisms and the wild. Additionally, it could be used to establish multi-viral resistance by rewriting code hijacked by viruses. This would be of particular interest to industries that cultivate bacteria, such as the pharmaceuticals and energy industries, where such viruses affect up to 20 percent of cultures resulting in losses in the billions of dollars.

"We're trying to challenge people to think about the genome as something that's highly malleable, highly editable," said Harris Wang, a research fellow at Harvard's Wyss Institute for Biologically Inspired Engineering

The technology, which is described in the July 15 issue of Science, is the result of a seven-year collaboration between researchers in the lab of Joseph Jacobson, associate professor in the MIT Media Lab, and George Church, professor of genetics at Harvard Medical School. Along with Wang, lead authors of the paper are Peter Carr, a research scientist at the MIT Media Lab, and Farren Isaacs, an assistant professor of molecular, cellular and developmental biology at Yale University.

Source: GizMag

While implantable heart pumps may buy some time for people waiting to undergo heart transplants, such implants have at least one serious drawback - because they receive their power from an external source, a power cord must protrude through the skin of the patient's belly. About 40 percent of patients experience infections of that opening, which often require rehospitalization, and in extreme cases can even cause death. The presence of that cord also makes it impossible for patients to swim or take baths. Researchers from the University of Washington and the University of Pittsburgh Medical Center are attempting to put an end to the troublesome cords, however, by developing a system that wirelessly transmits power to heart pumps.

A team led by UW associate professor of computer science and electrical engineering Joshua Smith, along with UPMC heart surgeon Pramod Bonde, created the prototype for the system. It utilizes a transmitting coil that sends out electromagnetic waves at a specific frequency, and a receiving coil that absorbs the energy from those waves, which it stores in a battery. It's a variation on the inductive power technology used in devices such as cell phone charging pads, the difference being that with those devices, the tool and the charger must be touching and held firmly in place.

The UW/UPMC system gets around that limitation, by automatically adjusting the frequency and other parameters as the transmitter and receiver move apart, or change orientation relative to one another. Presently, the wave strength is able to remain constant over a distance equivalent to the length of the transmitting coil. If a one-foot coil is used, for instance, that means it can effectively transmit power to the receiver over a distance of one foot.

If that coil were only a few inches long, that would still be sufficient for a scenario in which it were worn in a vest against the body, with the receiving coil adjacent to it, implanted under the patient's skin. Because energy would be stored in an implanted battery, that means the patient could spend periods of about two hours without having to even be near the transmitter, so they could do things like swim or bathe.

So far, the researchers have been able to use the system to power a heart pump submerged in water. Power was transmitted at about 80 percent efficiency, to a receiving coil that was just 4.3 centimeters (1.7 in) across. Animal trials are now being planned.

Ultimately, the UW/UPMC team would like to see a system in which several transmitters were located around a room, so a patient within that room could move freely about. They also believe that the technology could be used to power other types of implants, recharge consumer electronics, or even recharge underwater instruments in the ocean.

Source: GizMag

Well, because it's simpler and more efficient to send fishing boats out to catch the fish and bring them in. Thinking along those same lines, the Fraunhofer Center for Manufacturing Innovation has proposed a ship-mounted renewable energy-harvesting system, that would be powered by the ocean's waves.

Traditional wave-power systems, both actual and proposed, are typically permanently located out at sea. Because of this fact, they must be designed to withstand storms. They are also required to send the power that they generate back to shore via underwater cables, which can be very costly to purchase and install. Additionally, because they are permanent structures, they must meet regulatory standards and can't be located anywhere that ships might run into them.

A proposed wave-power system could be installed on ships, which would regularly return to shore to deliver power to the grid (Image: Fraunhofer)

The Fraunhofer system would apparently have none of these problems. It would consist of floating buoys, that would be deployed over the sides of a 50 meter (164 foot)-long ship, on hinged arms. As those buoys proceeded to bob up and down on the waves, the arms to which they were attached would pivot up and down, generating power that would be stored on an onboard battery system. One the ship was ashore, power from those batteries could then be released into the municipal grid system, during hours of peak usage.

Because the system would be mobile (the buoys would be lifted out of the water when the ship was moving), everything could simply be taken to shore when storms were approaching. No cables would be required, and the system could be temporarily parked wherever it didn't pose a hazard and the waves were decent.

The ships, which could be repurposed existing vessels, would have a storage capacity of 20 megawatt-hours. It is estimated that the system could generate electricity at a cost of 15 cents per kilowatt-hour, which is lower than the cost of existing wave power systems, that reportedly range between 30 and 65 cents.

Of course, some energy would be expended to power the ships' engines, or the engines of tug boats that would tow them.

Source: Gizmag

It sounds like the setup for a Hollywood thriller: scientists in a lab create a virus as contagious as the flu that kills half of those infected. We're safe as long as the virus remains locked up, but if it escapes or gets into the hands of bioterrorists, it has the potential to become a pandemic and kill millions around the world.

But this isn't the latest summer blockbuster. According to New Scientist magazine, researchers in the Netherlands studying H5N1 -- commonly referred to as the bird flu or avian influenza -- have created a strain of the virus that's easily passed between mammals, and it's just as lethal as the original virus.

According to the U.S. Department of Health & Human Services, the H5N1 virus has infected more than 500 people in more than a dozen countries and is known to kill around 60 percent of those that become infected.

Ron Fouchier, a researcher at the Erasmus Medical Centre in Rotterdam, led the team that successfully created the mutation. Fouchier presented the findings at a conference in Malta in September and, according to NPR, is now seeking publication of his results.

But some in the scientific community are debating whether or not that's a good idea.

"It's just a bad idea for scientists to turn a lethal virus into a lethal and highly contagious virus. And it's a second bad idea for them to publish how they did it so others can copy it," Dr. Thomas Inglesby, the director and CEO of the Center for Biosecurity at the University of Pittsburgh, told NPR.

Others, like Michael Osterholm, the director of the Center for Infectious Disease Research and Policy (CIDRAP), told Science magazine that "These studies are very important."

From the Science magazine blog Science Insider:

The researchers "have the full support of the influenza community," Osterholm says, because there are potential benefits for public health. For instance, the results show that those downplaying the risks of an H5N1 pandemic should think again, he says.

The study is currently being reviewed by the U.S. National Science Advisory Board for Biosecurity, a "federal advisory committee chartered to provide advice, guidance, and leadership regarding...biological research with legitimate scientific purpose that may be misused to pose a biologic threat to public health and/or national security."

What do you think? Should the results of the study be made public? Do the benefits outweigh the risks?

Source: huffingtonpost.com

A tool based on theoretical calculations that could aid the search for these particles has been developed by a team of researchers in Japan called the HAL QCD Collaboration.

At its most fundamental level, matter consists of particles known as quarks. Particle physicists refer to the six different types as ‘flavors’: up, down, charm, strange, top and bottom. The protons and neutrons found in the nucleus of an atom are examples of a class of particle called baryons: particles consisting of three quarks. Two baryons bound together are called dibaryons, but only one dibaryon has been found to date: a bound proton and neutron that has three up quarks and three down quarks in total.

Models that reveal the potential physical properties of dibaryons, such as their mass and binding energy, are crucial if more of these particles are to be discovered in the future. To this end, the collaboration, including Tetsuo Hatsuda from the RIKEN Nishina Center for Accelerator-Based Science in Wako, developed simulations that shed new light on one promising candidate: the H dibaryon, which comprises two up, two down and two strange quarks (Fig. 1).

An artistic impression of a bound H dibaryon, a theoretical particle consisting of two up, two down and two strange quarks. Credit: 2011 Keiko Murano

The dynamics of quarks are described by an intricate theory known as quantum chromodynamics (QCD). The simulations, however, become increasingly difficult when more particles need to be included: dibaryons with six quarks are particularly testing. Hatsuda and his colleagues used an approach known as lattice QCD in which time and space are considered as a grid of discrete points. They simplified the calculation by assuming that all quarks have the same mass, but the strange quark is actually heavier than the up and down quarks. “We know from previous theoretical studies that the binding energy should be at its largest in the equal mass case,” says Hatsuda. “If we had not found a bound state in the equal mass case, there would be no hope that the bound state exists in the realistic unequal mass case.”

The results from the collaboration’s simulations showed that the total energy of the dibaryon is less than the combined energy of two separate baryons, which verifies that H dibaryons are energetically stable. “We next hope to find the precise binding energy for unequal quark masses, which represents one of the major challenges in numerical QCD simulations,” Hatsuda adds.

Source: PhysOrg

By introducing silver or copper into the steel surface (rather than coating it on to the surface), the researchers have developed a technique that not only kills bacteria but is very hard and resistant to wear and tear during cleaning.

Bacteria resistant surfaces could be used in hospitals to prevent the spread of superbug infections on stainless steels surfaces, as well as in medical equipment, for example, instruments and implants. They would also be of use to the food industry and in domestic kitchens.

The team has developed a novel surface alloying technology using Active Screen Plasma (ASP) with a purpose designed composite or hybrid metal screen. The combined sputtering, back-deposition and diffusion allows the introduction of silver into a stainless steel surface, along with nitrogen and carbon. The silver acts as the bacteria killing agent and the nitrogen and carbon make the stainless steel much harder and durable.

The researchers replicated the cleaning process for medical instruments in hospitals. After cleaning the treated instruments 120 times they found that the antibacterial properties of the stainless steel were still intact and the surface still resistant to wear.

Hanshan Dong, Professor of Surface Engineering at the University of Birmingham and lead investigator, said: ‘Previous attempts to make stainless steel resistant to bacteria have not been successful as these have involved coatings which are too soft and not hard-wearing. Thin antibacterial coatings can be easily worn down when interacting with other surfaces, which leads to a low durability of the antibacterial surface. Our technique means that we avoid coating the surface, instead we modify the top layers of the surface.’

Professor Dong’s team are confident that this technique could be used in the manufacturing of stainless steel products as they are already able to surface engineer items of up to two metres x two metres in the laboratory.

Source: PhysOrg