#Why eumelanin is such a good absorber of light Melanin and specifically, the form called eumelanin is the primary pigment that gives humans the coloring of their skin, hair, and eyes.
It protects the body from the hazards of ultraviolet and other radiation that can damage cells and lead to skin cancer,
but the exact reason why the compound is so effective at blocking such a broad spectrum of sunlight has remained something of a mystery.
Now researchers at MIT and other institutions have solved that mystery, potentially opening the way for the development of synthetic materials that could have similar light-blocking properties.
The findings are published this week in the journal Nature Communications by graduate students Chun-Teh Chen and Chern Chuang, professor of civil and environmental engineering Markus Buehler,
and three others. Although eumelanin has been known for decades, pinning down its molecular structure, and identifying the reasons for its broadband light absorption,
The team used a combination of computation and experimental analysis to derive the structure of the material,
a graduate student in chemistry, says, here you isolate each component. Only indirect ways of probingcan be used,
The material forms tiny crystals a chemically ordered state but with intrinsic randomness such that the orientations of the stacked molecules can be arbitrary
and the sizes of the crystals different, forming aggregate structures that are disordered highly. That combination of order and disorder contributes to eumelanin broadband absorption, the team found. t a naturally existing nanocomposite,
Buehler says, hat has very critical macroscopic properties as a result of the nanostructure. While eumelanin molecules all share a basic chemistry,
more than 100 variations of that composition exist; the slight variations from one molecule to another may contribute to the disorder that broadens the ability to absorb light,
These insights may be useful in developing materials for applications such as pigments, he says, or in improving the efficiency of solar cells.
While this analysis still leaves open questions about the precise structure of eumelanin molecules, Buehler says,
uilding an accurate structural model is one of our big aims. A similar combination of computational modeling based on quantum mechanics
The new work, he says, rovides a somewhat unexpected answer to this conundrum. The researchersapproach, he says,
The research team also included Jianshu Cao, a professor of chemistry at MIT, Vincent Ball at the University of Strasbourg in France,
The work was funded partly by the U s. Department of energy through the Center for Excitonics at MIT
#Illuminating neuron activity in 3-D Researchers at MIT and the University of Vienna have created an imaging system that reveals neural activity throughout the brains of living animals.
says Ed Boyden, an associate professor of biological engineering and brain and cognitive sciences at MIT and one of the leaders of the research team. n short,
The new approach, described May 18 in Nature Methods, could also help neuroscientists learn more about the biological basis of brain disorders. e don really know
for any brain disorder, the exact set of cells involved, Boyden says. he ability to survey activity throughout a nervous system may help pinpoint the cells
or networks that are involved with a brain disorder, leading to new ideas for therapies. Boyden team developed the brain-mapping method with researchers in the lab of Alipasha Vaziri of the University of Vienna and the Research Institute of Molecular Pathology in Vienna.
The paper lead authors are Young-Gyu Yoon, a graduate student at MIT, and Robert Prevedel, a postdoc at the University of Vienna.
High-speed 3-D imaging Neurons encode information sensory data motor plans, emotional states, and thoughts using electrical impulses called action potentials,
which provoke calcium ions to stream into each cell as it fires. By engineering fluorescent proteins to glow when they bind calcium,
scientists can visualize this electrical firing of neurons. However, until now there has been no way to image this neural activity over a large volume, in three dimensions,
and at high speed. Scanning the brain with a laser beam can produce 3-D images of neural activity,
so they could see neuronal firing, which takes only milliseconds, as it occurs. The new method is based on a widely used technology known as light-field imaging,
Ramesh Raskar, an associate professor of media arts and sciences at MIT and an author of this paper, has worked extensively on developing this type of 3-D imaging.
which can then be recombined using a computer algorithm to recreate the 3-D structure. f you have one light-emitting molecule in your sample,
Aravinthan Samuel, a professor of physics at Harvard university, says this approach seems to be an xtremely promisingway to speed up 3-D imaging of living, moving animals,
They also hope to speed up the computing process, which currently takes a few minutes to analyze one second of imaging data.
The researchers also plan to combine this technique with optogenetics, which enables neuronal firing to be controlled by shining light on cells engineered to express light-sensitive proteins.
By stimulating a neuron with light and observing the results elsewhere in the brain, scientists could determine which neurons are participating in particular tasks.
Other co-authors at MIT include Nikita Pak, a Phd student in mechanical engineering, and Gordon Wetzstein, a research scientist at the Media Lab. The work at MIT was funded by the Allen Institute for Brain science;
the National institutes of health; the MIT Synthetic Intelligence Project; the IET Harvey Prize; the National Science Foundation (NSF;
Google; the NSF Center for Brains, Minds, and Machines at MIT; and Jeremy and Joyce Wertheimer n
#Glasses-free 3-D projector Over the past three years, researchers in the Camera Culture group at the MIT Media Lab have refined steadily a design for a glasses-free, multiperspective, 3-D video screen,
This means it might have applications in areas like collaborative design and medical imaging, as well as entertainment.
The MIT researchers research scientist Gordon Wetzstein, graduate student Matthew Hirsch, and Ramesh Raskar, the NEC Career development Associate professor of Media Arts and Sciences and head of the Camera Culture group built a prototype of their system using off-the-shelf components.
The heart of the projector is a pair of liquid-crystal modulators which are like tiny liquid-crystal displays (LCDS) positioned between the light source and the lens.
Patterns of light and dark on the first modulator effectively turn it into a bank of slightly angled light emitters that is,
The screen combines two lenticular lenses the type of striated transparent sheets used to create crude 3-D effects in,
Exploiting redundancy For every frame of video, each modulator displays six different patterns which together produce eight different viewing angles:
But like the researchersprototype monitors, the projector takes advantage of the fact that, as you move around an object,
but by tailoring their algorithm to the architecture of the graphics processing units designed for video games,
Their system can receive data in the form of eight images per frame of video
Bridge technology Passing light through two modulators can also heighten the contrast of ordinary 2-D video.
One of the problems with LCD screens is that they don enable rue black A little light always leaks through even the darkest regions of the display. ormally you have contrast of,
Again, the researchers have developed an algorithm that can calculate those patterns on the fly. As content creators move to so-called uad HD, video with four times the resolution of today high-definition video, the combination of higher contrast and higher resolution could make a commercial version of the researcherstechnology appealing to theater owners,
and project through it and use this software algorithm, and you end up with a 4k image.
Spreading pixels Oliver Cossairt, an assistant professor of electrical engineering and computer science at Northwestern University, once worked for a company that was attempting to commercialize glasses-free 3-D projectors. hat
is the prototype screen. here is this invariant of optical systems that says that if you take the area of the plane
We couldn figure out a way around that. hey came up with a screen that instead of stretching the image
which is what projection optics does moved essentially the pixels away from each other, Cossairt continues. hat allowed them to break this invariance
#High-flying turbine produces more power For Altaeros Energies a startup launched out of MIT the sky s the limit
and Adam Rein MBA 10 Altaeros has developed the world s first commercial airborne wind turbine which uses a helium-filled shell to float as high as a skyscraper and capture the stronger steadier winds available at that altitude.
Proven to produce double the energy of similarly sized tower-mounted turbines the system called Buoyant Air Turbine
Surrounded by a circular 35-foot-long inflatable shell made of the same heavy-duty fabric used in blimps
and sails the BAT hovers 1000 to 2000 feet above ground where winds blow five to eight times stronger as well as more consistently than winds at tower level (roughly 100 to 300 feet).
Power generated by the turbine travels down one of the tethers to the ground station before being passed along to microgrids.
Think of it as a reverse crane says Glass who invented the core BAT technology. A crane has a nice stationary component
Next year the BAT will test its ability to power microgrids at a site south of Fairbanks Alaska in an 18-month trial funded by the Alaska Energy Authority.
and diesel generators for power paying upward of $1 per kilowatt-hour for electricity. The BAT which has a capacity of 30 kilowatts aims to drop that kilowatt-hour cost down to roughly 18 cents the cofounders say.
But despite its efficiency the BAT is designed not to replace conventional tower-mounted turbines Rein says.
Instead its purpose is to bring wind power to remote off-grid areas where towers aren t practically or economically feasible.
Conventional turbine construction for instance requires tons of concrete and the use of cranes which can be difficult to maneuver around certain sites.
The modular BAT Rein says packs into two midsize shipping containers for transport and can just be inflated out and self-lift into the air for installation.
Target sites include areas where large diesel generators provide power such as military bases and industrial sites as well as island and rural communities in Hawaii northern Canada India Brazil and parts of Australia.
The BAT could also provide power to places blacked out by natural disasters as well as at amusement parks festivals and sports venues.
It s really about expanding wind energy to all those places on the fringes where it doesn t really work today
Aerostat innovationmuch of the BAT s innovation lies in its complete autonomy Glass says. Such aerostats usually require full-time ground crews to deploy land
and adjust. But the BAT automatically adjusts to optimal wind speeds and self-docks in case of emergencies eliminating the need for manual labor.
But if winds get too high above the maximum capacity of the turbine there s no reason to operate in those very strong winds
When the anemometers detect optimal wind speed a custom algorithm adjusts the system s tethers to extend
which protects the system s electronics from lightning strikes will self-dock. Because the BAT is advanced an aerostat platform Glass says customers can use it to lift additional payloads such as weather monitoring and surveillance equipment.
But perhaps the most logical added payload Glass says is Wi-fi technology: If you have a remote village for instance he says you can put a Wi-fi unit up outside the village
and you re much higher than you d get with a traditional tower. That would allow you to cover six to eight times the area you would with a tower.
Prototype to productglass first conceived of the BAT while working at MIT toward his master s degree in aeronautics and astronautics.
Harboring an interest in wind turbine design and knowing that traditional towers could never reach high-altitude winds he designed the BAT in his free time receiving technical guidance from Institute Professor Sheila Widnall and other faculty.
Soon he d bring his concept to 15.366 (Energy Ventures) a class at the MIT Sloan School of management where engineering policy and business students build startups around clean tech ideas.
At the time Rein who had done independent research on clean energy was an MBA student and teacher s assistant for the class who helped Glass flesh out an initial business model.
The duo along with Harvard university grad student Alain Goubau and investor Alex Rohde then an Alfred P. Sloan Fellow soon formed Altaeros.
They solicited advice from seasoned entrepreneurs at MIT s Venture Mentoring Service (VMS) our first advisory board Rein says who steered the startup toward rapid prototyping by using low-cost off-the-shelf materials.
For their first power-producing prototype they bought a small reliable wind turbine rotor and cut off some metal in the back that was dead weight
and built a composite nacelle to hold our custom electronics and control systems Rein says. In 2012 Altaeros after just two years of refining proved the BAT s efficiency at 300 feet above ground at a former Air force base in Maine where the company still assembles
and tests the system. They did so again last August at 500 feet in 45-mph winds.
Altaeros remains headquartered in cleantech incubator Greentown Labs (which Rein co-founded) in Somerville Mass. where its first rotor is displayed proudly near the entrance along with enlarged photos of the first trial run.
At Greentown employees engage in computer modeling and design build electronics and circuit boards develop algorithms
and test winches and cables Looking back Glass credits his undergraduate years on MIT s Solar Electrical Vehicle Team a student organization that builds and races solar
cars for competition with giving him the experience and motivation to bring the BAT from concept to reality.
Just being able to see a project from design and analysis stage through building testing
and operating was valuable he says. It s also something that helped in leading a technical team at Altaeros to essentially do the same thing on a bigger scale.
For now Altaeros is focused on finalizing the commercial product for Alaska and eventually deploying the technology worldwide.
To take the system from concept to actual prototype has been exciting Glass says. But the next step is making the prototype a commercial product
and really seeing its real-world performance r
#Who did what? With the commodification of digital cameras digital video has become so easy to produce that human beings can have trouble keeping up with it.
Among the tools that computer scientists are developing to make the profusion of video more useful are algorithms for activity recognition or determining
what the people on camera are doing when. At the Conference on Computer Vision and Pattern Recognition in June Hamed Pirsiavash a postdoc at MIT and his former thesis advisor Deva Ramanan of the University of California at Irvine will present a new activity
-recognition algorithm that has several advantages over its predecessors. One is that the algorithm s execution time scales linearly with the size of the video file it s searching.
That means that if one file is 10 times the size of another the new algorithm will take 10 times as long to search it not 1000 times
as long as some earlier algorithms would. Another is that the algorithm is able to make good guesses about partially completed actions
so it can handle streaming video. Partway through an action it will issue a probability that the action is of the type that it s looking for.
It may revise that probability as the video continues but it doesn t have to wait until the action is complete to assess it.
Finally the amount of memory the algorithm requires is fixed regardless of how many frames of video it s already reviewed.
That means that unlike many of its predecessors it can handle video streams of any length (or files of any size.
The grammar of actionenabling all of these advances is the appropriation of a type of algorithm used in natural language processing the computer science discipline that seeks techniques for interpreting sentences written in natural language.
One of the challenging problems they try to solve is if you have a sentence you want to basically parse the sentence saying what is the subject
For any given action Pirsiavash and Ramanan s algorithm must thus learn a new grammar.
machine learning. Pirsiavash and Ramanan feed their algorithm training examples of videos depicting a particular action
and specify the number of subactions that the algorithm should look for. But they don t give it any information about
what those subactions are or what the transitions between them look like. Pruning possibilitiesthe rules relating subactions are the key to the algorithm s efficiency.
As a video plays the algorithm constructs a set of hypotheses about which subactions are being depicted where
and it ranks them according to probability. It can t limit itself to a single hypothesis as each new frame could require it to revise its probabilities.
The researchers tested their algorithm on eight different types of athletic endeavor such as weightlifting and bowling with training videos culled from Youtube.
They found that according to metrics standard in the field of computer vision their algorithm identified new instances of the same activities more accurately than its predecessors.
Pirsiavash is interested particularly in possible medical applications of action detection. The proper execution of physical-therapy exercises for instance could have a grammar that s distinct from improper execution;
similarly the return of motor function in patients with neurological damage could be identified by its unique grammar.
Action-detection algorithms could also help determine whether for instance elderly patients remembered to take their medication
if they didn t. We ve known for a very long time that the things that people do are made up of subactivities says David Forsyth a professor of computer science at the University of Illinois at Urbana-Champaign.
and nobody has given us labeled training data saying There are two pieces in a dive and seven pieces in a weightlifting and 21 pieces in a hammer throw and these are their names.
holds great potential for treating many diseases caused by malfunctioning genes. However, it has been difficult for scientists to find safe and effective ways to deliver gene-blocking RNA to the correct targets.
Up to this point, researchers have gotten the best results with RNAI targeted to diseases of the liver,
in part because it is a natural destination for nanoparticles. But now, in a study appearing in the May 11 issue of Nature Nanotechnology,
an MIT-led team reports achieving the most potent RNAI gene silencing to date in nonliver tissues.
Using nanoparticles designed and screened for endothelial delivery of short strands of RNA called sirna,
This raises the possibility of using RNAI to treat many types of disease, including cancer and cardiovascular disease,
the researchers say. here been a growing amount of excitement about delivery to the liver in particular,
but in order to achieve the broad potential of RNAI therapeutics, it important that we be able to reach other parts of the body as well,
says Daniel Anderson, the Samuel A. Goldblith Associate professor of Chemical engineering, a member of MIT Koch Institute for Integrative Cancer Research and Institute for Medical Engineering and Science,
The paper other senior author is Robert Langer, the David H. Koch Institute Professor at MIT and a member of the Koch Institute.
Lead authors are MIT graduate student James Dahlman and Carmen Barnes of Alnylam Pharmaceuticals. Targeted delivery RNAI is a naturally occurring process,
Genetic information is carried normally from DNA in the nucleus to ribosomes, cellular structures where proteins are made.
Short strands of RNA called sirna bind to the MESSENGER RNA that carries this genetic information preventing it from reaching the ribosome.
Anderson and Langer have developed previously nanoparticles, now in clinical development, that can deliver sirna to liver cells called hepatocytes by coating the nucleic acids in fatty materials called lipidoids.
because they resemble the fatty droplets that circulate in the blood after a high-fat meal is consumed. he liver is a natural destination for nanoparticles,
if you inject nanoparticles into the blood, they are likely to end up there. Scientists have had some success delivering RNA to nonliver organs
or more concentric spheres made of short chains of a chemically modified polymer. RNA is packaged within each sphere
400 variants of their particles in cervical cancer cells by measuring whether they could turn off a gene coding for a fluorescent protein that had been added to the cells.
With the best-performing particles, the researchers reduced gene expression by more than 50 percent, for a dose of only 0. 20 milligrams per kilogram of solution about one-hundredth of the amount required with existing endothelial
RNAI delivery vehicles. They also showed that they could block up to five genes at once by delivering different RNA sequences.
they did not enter liver hepatocytes. hat interesting is that by changing the chemistry of the nanoparticle you can affect delivery to different parts of the body,
To demonstrate the potential for treating lung disease, the researchers used the nanoparticles to block two genes that have been implicated in lung cancer VEGF receptor 1 and Dll4,
which promote the growth of blood vessels that feed tumors. By blocking these in lung endothelial cells,
the researchers were able to slow lung tumor growth in mice and also reduce the spread of metastatic tumors.
Masanori Aikawa, an associate professor of medicine at Harvard Medical school, describes the new technology as monumental contributionthat should help researchers develop new treatments
and learn more about diseases of endothelial tissue such as atherosclerosis and diabetic retinopathy, which can cause blindness. ndothelial cells play a very important role in multiple steps of many diseases, from initiation to the onset of clinical complications,
says Aikawa, who was not part of the research team. his kind of technology gives us an extremely powerful tool that can help us understand these devastating vascular diseases.
The researchers plan to test additional potential targets in hopes that these particles could eventually be deployed to treat cancer, atherosclerosis,
and other diseases. Scientists from Alnylam Pharmaceuticals and Harvard Medical school also contributed to the study,
which was funded by a National Defense Science and Engineering Fellowship, the National Science Foundation, MIT Presidential Fellowships, the National institutes of health, the Stop and Shop Pediatric Brain tumor Fund,
the Pediatric Brain Tumour Fund, the Deutsche Forschungsgemeinschaft, Alnylam, and the Center for RNA Therapeutics and Biology e
#Chemotherapy timing is key to success MIT researchers have devised a novel cancer treatment that destroys tumor cells by first disarming their defenses,
then hitting them with a lethal dose of DNA damage. In studies with mice, the research team showed that this one-two punch,
which relies on a nanoparticle that carries two drugs and releases them at different times,
dramatically shrinks lung and breast tumors. The MIT team, led by Michael Yaffe, the David H. Koch Professor in Science,
and Paula Hammond, the David H. Koch Professor in Engineering, describe the findings in the May 8 online edition of Science Signaling. think it a harbinger of what nanomedicine can do for us in the future,
says Hammond, who is a member of MIT Koch Institute for Integrative Cancer Research. ee moving from the simplest model of the nanoparticle just getting the drug in there
and targeting it to having smart nanoparticles that deliver drug combinations in the way that you need to really attack the tumor.
Doctors routinely give cancer patients two or more different chemotherapy drugs in hopes that a multipronged attack will be more successful than a single drug.
While many studies have identified drugs that work well together, a 2012 paper from Yaffe lab was the first to show that the timing of drug administration can dramatically influence the outcome.
In that study Yaffe and former MIT postdoc Michael Lee found they could weaken cancer cells by administering the drug erlotinib,
which shuts down one of the pathways that promote uncontrolled tumor growth. These pretreated tumor cells were much more susceptible to treatment with a DNA-damaging drug called doxorubicin than cells given the two drugs simultaneously. t like rewiring a circuit,
says Yaffe, who is also a member of the Koch Institute. hen you give the first drug,
the wiresconnections get switched around so that the second drug works in a much more effective way.
Erlotinib, which targets a protein called the epidermal growth factor (EGF) receptor found on tumor cell surfaces,
has been approved by the Food and Drug Administration to treat pancreatic cancer and some types of lung cancer.
Doxorubicin is used to treat many cancers, including leukemia, lymphoma, and bladder, breast, lung, and ovarian tumors.
Staggering these drugs proved particularly powerful against a type of breast cancer cell known as triple-negative,
which doesn have overactive estrogen, progesterone, or HER2 receptors. Triple-negative tumors, which account for about 16 percent of breast cancer cases,
are much more aggressive than other types and tend to strike younger women. That was an exciting finding
Yaffe says. he problem was, he adds, ow do you translate that into something you can actually give a cancer patient?
From lab result to drug delivery To approach this problem, Yaffe teamed up with Hammond,
a chemical engineer who has designed previously several types of nanoparticles that can carry two drugs at once.
For this project, Hammond and her graduate student, Stephen Morton, devised dozens of candidate particles. The most effective were a type of particle called liposomes spherical droplets surrounded by a fatty outer shell.
The MIT team designed their liposomes to carry doxorubicin inside the particle core, with erlotinib embedded in the outer layer.
The particles are coated with a polymer called PEG, which protects them from being broken down in the body
or filtered out by the liver and kidneys. Another tag folate, helps direct the particles to tumor cells,
which express high quantities of folate receptors. Once the particles reach a tumor and are taken up by cells, the particles start to break down.
Erlotinib, carried in the outer shell, is released first, but doxorubicin release is delayed and takes more time to seep into cells,
giving erlotinib time to weaken the cellsdefenses. here a lag of somewhere between four and 24 hours between
The researchers tested the particles in mice implanted with two types of human tumors: triple-negative breast tumors and non-small-cell lung tumors.
Both types shrank significantly. Furthermore, packaging the two drugs in liposome nanoparticles made them much more effective than the traditional forms of the drugs,
even when those drugs were given in a time-staggered order. his particle delivery system not only provides a platform for time-staggered treatment strategies in cancer,
but also for delivering the drugs more directly to the tumor tissue itself, says Rune Linding,
a professor of systems biology at the Technical University of Denmark who was not part of the research team. he latter is vital,
as one of the major drawbacks of traditional chemotherapy is the general wipeout of normal cells in the patient body,
As a next step before possible clinical trials in human patients, the researchers are now testing the particles in mice that are programmed genetically to develop tumors on their own,
instead of having human tumor cells implanted in them. The researchers believe that time-staggered delivery could also improve other types of chemotherapy.
and ovarian cancers. At the same time, Hammond lab is working on more complex nanoparticles that would allow for more precise loading of the drugs
and fine-tuning of their staggered release. ith a nanoparticle delivery platform that allows us to control the relative rates of release and the relative amounts of loading,
we can put these systems together in a smart way that allows them to be as effective as possible,
and Kevin Shopsowitz, visiting student Elise Siouve, and graduate student Nisarg Shah also contributed to the research.
The work was funded by the National institutes of health, the Center for Cancer Nanotechnology Excellence, the Koch Institute Frontier Research Program supported by the Kathy and Curt Marble Fund for Cancer Research,
and a Breast cancer Alliance Exceptional Project Grant
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