#Light-based memory chip is first to permanently store data Today electronic computer chips work at blazing speeds.
But an alternate version that stores, manipulates, and moves data with photons of light instead of electrons would make today chips look like proverbial horses and buggies.
Now, one team of researchers reports that it has created the first permanent optical memory on a chip,
a critical step in that direction. am very positive about the work, says Valerio Pruneri, a laser physicist at the Institute of Photonic Sciences in Barcelona, Spain,
who was involved not in the research. t a great demonstration of a new concept. Interest in so-called photonic chips goes back decades
and it easy to see why. When electrons move through the basic parts of a computer chipogic circuits that manipulate data,
memory circuits that store it, and metal wires that ferry it alonghey bump into one another, slowing down and generating heat that must be siphoned away.
Researchers have made already photon-friendly chips, with optical lines that replace metal wires and optical memory circuits.
can store data only if they have a steady supply of power. When the power is turned off,
the data disappear, too. Now, researchers led by Harish Bhaskaran, a nanoengineering expert at the University of Oxford in the United kingdom,
and electrical engineer Wolfram Pernice at the Karlsruhe Institute of technology in Germany, have hit on a solution to the disappearing memory problem using a material at the heart of rewritable CDS and DVDS.
That materialbbreviated GSTONSISTS of a thin layer of an alloy of germanium, antimony, and tellurium.
When zapped with an intense pulse of laser light GST film changes its atomic structure from an ordered crystalline lattice to an morphousjumble.
and CDS and DVDS use this difference to store data. To read out the datatored as patterns of tiny spots with a crystalline
or amorphous order CD or DVD drive shines low-intensity laser light on a disk and tracks the way the light bounces off.
In their work with GST, the researchers noticed that the material affected not only how light reflects off the film,
whether they could use this property to permanently store data on a chip and later read it Out to do used so,
they standard chipmaking technology to outfit a chip with a silicon nitride device, known as a waveguide,
They then placed a nanoscale patch of GST atop this waveguide. To write data in this layer,
the scientists piped an intense pulse of light into the waveguide. The high intensity of the light electromagnetic field melted the GST
turning its crystalline atomic structure amorphous. A second, slightly less intense pulse could then cause the material to revert back to its original crystalline structure.
When the researchers wanted to read the data, they beamed in less intense pulses of light and measured how much light was transmitted through the waveguide.
If little light was absorbed, they knew their data spot on the GST had an amorphous order;
if more was absorbed, that meant it was crystalline. Bhaskaran, Pernice, and their colleagues also took steps to dramatically increase the amount of data they could store
and read. For starters, they sent multiple wavelengths of light through the waveguide at the same time, allowing them to write
and read multiple bits of data simultaneously, something you can do with electrical data storage devices. And, as they report this week in Nature Photonics,
by varying the intensity of their data-writing pulses, they were also able to control how much of each GST patch turned crystalline or amorphous at any one time.
With this method they could make one patch 90%amorphous but just 10%crystalline, and another 80%amorphous and 20%crystalline.
That made it possible to store data in eight different such combinations, not just the usual binary 1s and 0s that would be used for 100%amorphous or crystalline spots.
This dramatically boosts the amount of data each spot can store, Bhaskaran says. Photonic memories still have a long way to go
if they ever hope to catch up to their electronic counterparts. At a minimum, their storage density will have to climb orders of magnitude to be competitive.
Ultimately Bhaskaran says, if a more advanced photonic memory can be integrated with photonic logic and interconnections,
the resulting chips have the potential to run at 50 to 100 times the speed of today computer processors f
Previous guidelines called for only treating the estimated 28 million HIV-infected people who have fewer than 500 CD4 lymphocytes per microliter of blood.
or Prepo all people at ubstantial riskof infection. Currently, only 15 million HIV-infected people are receiving antiretrovirals.
But in rich countries, it's becoming more and more common to start therapy early, before a patient's CD4 cells have had significant declines.
Large studies have shown that early treatment benefits HIV-infected people and, separately, that ARVS dramatically reduce the risk of transmission.
The Joint United nations Programme on HIV/AIDS earlier called for a ast-trackapproach to end the world AIDS epidemic by 2030 that would increase the necessary annual investmentsow at $21. 7 billiony $12 billion.
Doing so will require more domestic spending by low-income countries that are hardest hit by the epidemic as well as larger contributions from wealthy nations.
which point ARVS were recommended only for people who had fewer than 200 CD4S d
#Designer antibodies may rid body of AIDS virus Anti-HIV drugs have extended life for millions of people,
but they have eliminated never the virus from anyone. That because HIV integrates its genetic material into the chromosomes of some white blood cells,
helping it escape notice of the immune system. Two new studies show that artificial antibodies could edirectthe immune response to these latently infected cells
and help drain those HIV reservoirs in the body. But this creative strategy also carries risks. he rationale is sound,
and the data are exciting, but we will need to move carefully, says Steven Deeks, an HIV/AIDS clinician at the University of California, San francisco (UCSF),
who tests cure strategies. here really is zero room for error. Several previous studies have explored
whether drugs can shock cells that are infected with latent HIV to make new viruses, setting them up for the kill by the natural immune response.
But this new work ups the ante by designing so-called bispecific antibodies that both promise to reverse latency
a HIV cure researcher who directs the Peter Doherty Institute for Infection and Immunity in Melbourne,
was conducted by a team from the Vaccine Research center at the U s. National Institute of Allergy and Infectious diseases (NIAID) in Bethesda, Maryland.
and involved a collaboration between three universities and a biotech company. Both groups designed artificial versions of antibodies, the Y-shaped molecules made by the immune system to target pathogens.
With natural antibodies, both rmsof the Y clasp the same target. But the arms of bispecific antibodies each grab a unique protein.
In this case both teams designed their antibodies to clasp an HIV protein and CD3, a receptor found on the surface of white blood cells.
The bispecific antibodies focus on the CD3 receptor for two reasons. One is that HIV hides its DNA inside white blood cells,
or T lymphocytes, that have CD3 receptors. The other is that a second type of CD3-studded lymphocyte known as a killer T cell destroys HIV-infected cells.
The bispecific antibody first binds to CD3 on cells that harbor latent HIV. This prompts the cells to divide, an ctivationprocess that wakes up the sleeping virus. New HIV proteins are produced subsequently that migrate to the surface of the cell.
Now the bispecific antibody grabs a killer T cell that has a CD3 receptor and, with its second arm, finds a recently activated cell that has HIV proteins on its surface.
Bringing the killer T cell in close proximity to the infected cell effectively stuffs the prey into the lion mouth. he molecule works
just as you hope it would in several assays, says John Mascola, director of NIAID Vaccine Research center and head of the group reporting the Nature Communications study.
But neither team has shown yet that their bispecific antibodies can actually reduce reservoirs of HIV in monkeys
which are used commonly to study the AIDS virus. Those studies are underway, and it will take at least a year before either team tests the concepts in HIV-infected people.
David Margolis, a virologist at the University of North carolina, Chapel hill, and co-author of the JCI study,
says draining a reservoir ultimately may require combining bispecific antibodies with other latency reversing approaches and immune system stimulators like anti-HIV vaccines.
UCSF Deeks cautions that anti-CD3 antibodies can cause too much activation of T cells, leading to a massive inflammatory reaction that damages organs and can even cause death.
in one 1999 study of anti-CD3 antibodies used to purge reservoirs in three HIV-infected people,
But the anti-CD3 antibodies in the earlier study had both arms, Mascola notes, which led to far more activation than the single arm in the new bispecific antibodies.
He further points out that two cancer bispecific antibodies on the market both have anti-CD3 arms. he key is to find the right balance between CD3 activation and toxicity,
Mascola says. hat the real challenge here. c
#Researchers create a sonic tractor beam Using a simple set of loudspeakers, scientists have figured out a way to levitate
and rotate objects in midair. If perfected, this onic tractor beamcould find uses ranging from treating kidney stones to creating artificial gravity on the International space station.
Scientists have used sound to levitate objects before. That feat isn't surprising, as sound is a wave of pressure strong enough to move your eardrum.
scientists had to put banks of speakers on opposite sides of it, or a bank on one side and a sound reflector on the other.
In the new study, reported online today in Nature Communications, physicists achieve levitation using just one block of speakers on one side.
To do that, they employ a special algorithm that calculates the exact interference patterns needed to levitate an object using this ingle-sided emitter.
a mechanical engineer at University of Bristol in the United kingdom. oue got this array of loudspeakers
But with the algorithm help, Drinkwater and his colleagues were able to dictate the bead motion
or danced from side to side. fter we got the algorithm working, we put the bead in
and it just stayed theret was absolutely amazing The algorithm works by constructing the best possible interference patterns,
As the algorithm tunes the phases, the interference pattern and resulting hologram change, enabling researchers to move the bead around.
The algorithm can fashion acoustic holograms of various spatial configurations, but Drinkwater and his team focused on three:
Tony Jun Huang, a mechanical engineer at Pennsylvania State university, University Park, says he hopes this brings acoustic manipulation into the spotlight. ot many people work in this field,
Drinkwater and his colleagues will pair with biologists and doctors to demonstrate applications that until now,
were impossible to explore. And that exactly what Drinkwater and Asier Marzo, first author and computational engineer at the University of Bristol, hope to do next. y main target for the future is in vivo levitation,
Marzo says. Ultrasonic waves can penetrate the body relatively gently, he notes, so the sonic tractor beam might be used to remove kidney stones
and clots, deliver drug-laden capsules to various parts of the body, or control microsurgical instruments. his isn just theoretical anymore,
potentially offering an easy way to monitor the assembly of nanoparticles, or to study how mass is distributed within a cell.
known as a suspended microchannel resonator (SMR), measures particlesmasses as they flow through a narrow channel.
The original mass sensor consists of a fluid-filled microchannel etched in a tiny silicon cantilever that vibrates inside a vacuum cavity.
or spherical, says grad student Nathan Cermak, one of the paper lead authors. Postdoc Selim Olcum is also a lead author of the paper;
Manalis, the Andrew and Erna Viterbi Professor in MIT departments of Biological engineering and Mechanical engineering, and a member of MIT Koch Institute for Integrative Cancer Research, is the paper senior author.
Many frequenciesto obtain information about the mass distribution, the researchers took advantage of the fact that each cantilever,
and to measure how each particle affects the vibration frequency of each mode at each point along the resonator.
This has an internal oscillator that adjusts its own frequency to correspond to the frequency of a resonator mode,
the device can attain a resolution of about 150 nanometers. The researchers also calculated that
they could improve the resolution to about 4 nanometers. High-resolution mass imagingthis advance could help spur the development of a technique known as inertial imaging,
which makes use of several vibration modes to image an object as it sits on a nanomechanical resonator.
such as viruses or single molecules. ultimode mass sensing has previously been limited to air or vacuum environments,
where objects must be attached to the resonator. The ability to achieve this dynamically in flow opens up exciting possibilities,
The new MIT technology could enable very high-speed inertial imaging as cells flow through a channel. he suspended nanochannel technology pioneered by the Manalis group is remarkable
says Michael Roukes, a professor of physics, applied physics, and bioengineering at Caltech, who is pioneering the development of inertial imaging
but was not part of this study. heir application of our approach for simultaneous monitoring position
as they flow through the nanochannels. analislab is also using the new technique to study how cellsdensities change as they pass through constrictions.
They are also using the PLL approach to increase throughput by operating many cantilevers on a single chip.
The research was funded by the U s army Research Office, the Center for Integration of Medicine and Innovative Technology,
#Researchers identify new target for anti-malaria drugs A new target for drug development in the fight against the deadly disease malaria has been discovered by researchers at MIT.
which causes toxoplasmosis, and Plasmodium, which causes malaria, access vital nutrients from their host cells.
Around one-third of the world deadly infectious diseases, including malaria and tuberculosis, are caused by pathogens that spend a large portion of their life inside specially built compartments within their host cells.
These compartments known as arasitophorous vacuoles, separate the host cytoplasm and the parasite by a membrane,
and thereby protect the parasites from the host cell defenses. They also provide an environment tailored to their needs, according to Dan Gold,
a postdoc who led the research in the laboratory of Jeroen Saeij, the Robert A. Swanson Career development Associate professor of Life sciences in MIT Department of biology.
However, the membrane of these vacuoles also acts as a barrier between the parasite and the host cell.
This makes it more difficult for the parasite to release proteins involved in the transformation of the host cell beyond the membrane in order to spread the disease
and for the pathogen to gain access to vital nutrients, Gold says. ltimately what defines a parasite is that they require certain key nutrients from their host,
Similar research into how the related Plasmodium pathogen performs this trick had identified a so-called rotein export complexthat transports encoded proteins from the parasite into its host red blood cell,
which transforms these red blood cells in a way that is vital to the spread of malaria. he clinical symptoms of malaria are dependent on this process
they could be used as a drug target against the diseases they cause, including malaria, he says. his very strongly suggests that you could find small-molecule drugs to target these pores,
which would be very damaging to these parasites, but likely wouldn have any interaction with any human molecules,
he says. o I think this is a really strong potential drug target for restricting the access of these parasites to a set of nutrients. n addition to malaria,
which affects cattle and poultry, among other animals, and therefore has a huge economic cost,
a professor of immunology and infectious diseases at Harvard School of Public health who was involved not in the research. trikingly,
#How chronic inflammation can lead to cancer Chronic inflammation caused by disease or exposure to dangerous chemicals has long been linked to cancer,
but exactly how this process takes place has remained unclear. Now, a precise mechanism by which chronic inflammation can lead to cancer has been uncovered by researchers at MIT a development that could lead to improved targets for preventing future tumors.
In a paper published this week in the Proceedings of the National Academy of Sciences,
the researchers unveil how one of a battery of chemical warfare agents used by the immune system to fight off infection can itself create DNA mutations that lead to cancer.
As many as one in five cancers are believed to be caused or promoted by inflammation These include mesothelioma,
a type of lung cancer caused by inflammation following chronic exposure to asbestos, and colon cancer in people with a history of inflammatory bowel disease, says Bogdan Fedeles,
a research associate in the Department of Biological engineering at MIT, and the paper lead author.
Innate immune response Inflammation is part of the body innate response to invading pathogens or potentially harmful irritants.
The immune system attacks the invader with a number of reactive molecules designed to neutralize it,
including hydrogen peroxide, nitric oxide and hypochlorous acid. However, these molecules can also cause collateral damage to healthy tissue around the infection site:
he presence of a foreign pathogen activates the immune response, which tries to fight off the bacteria,
but in this process it also damages some of the normal cells, Fedeles explains. Previous work by Peter Dedon, Steven Tannenbaum, Gerald Wogan,
and James Fox all professors of biological engineering at MIT had identified the presence of a lesion,
or site of damage in the structure of DNA, called 5-chlorocytosine (5clc) in the inflamed tissues of mice infected with the pathogen Helicobacter hepaticus.
This lesion, a damaged form of the normal DNA base cytosine, is caused by the reactive molecule hypochlorous acid the main ingredient in household bleach
which is generated by the immune system. The lesion 5clc, was present in remarkably high levels within the tissue,
says John Essigmann, the William R. 1956) and Betsy P. Leitch Professor in Residence Professor of Chemistry, Toxicology and Biological engineering at MIT,
who led the current research. hey found the lesions were very persistent in DNA, meaning we don have a repair system to take them out,
Essigmann says. n our field lesions that are persistent, if they are also mutagenic, are the kind of lesions that would initiate cancer,
he adds. DNA sequencing of a developing gastrointestinal tumor revealed two types of mutation: cytosine (C) bases changing to thymine (T) bases,
and adenine (A) bases changing to guanine (G) bases. Since 5clc had not yet been studied as a potentially carcinogenic mutagen,
the researchers decided to investigate the lesion further, in a bid to uncover if it is indeed mutagenic.
Using a technique previously developed in Essigmann laboratory, the researchers first placed the 5clc lesion at a specific site within the genome of a bacterial virus. They then replicated the virus within the cell.
The researchers found that, rather than always pairing with a guanine base as a cytosine would,
the 5clc instead paired with an adenine base around 5 percent of the time a medically relevant mutation frequency, according to Essigmann.
when triggered by infection, fires hypochlorous acid at the site, damaging cytosines in the DNA of the surrounding healthy tissue.
he explains. his scenario would best explain the work of James Fox and his MIT colleagues on gastrointestinal cancer.
the researchers replicated the genome containing the lesion with a variety of different types of polymerase,
and causes the same kind of mutations seen within cells, Fedeles says. hat gave us confidence that this phenomenon would in fact happen in human cells containing high levels of 5clc.
the C-to-T mutation characteristic of 5clc is extremely common, and is present in more than 50 percent of mutagenic ignatures,
or patterns of DNA mutations, associated with cancerous tumors. e believe that in the context of inflammation-induced damage of DNA,
many of these C-to-T mutations may be caused by 5clc, possibly in correlation with other types of mutations as part of these mutational signatures,
Yinsheng Wang, a principal investigator in the Department of chemistry at the University of California at Riverside who was involved not in the research,
says the paper provides a novel mechanistic link between chronic inflammation and cancer development. ith a combination of biochemical,
genetic, and structural biology approaches, the researchers have found that 5-chlorocytosine is intrinsically miscoding during DNA replication
and it could give rise to significant frequencies of C-to-T mutation, a type of mutation that is frequently observed in human cancers,
Wang says. Studies of tissue samples of patients suffering from inflammatory bowel disease have found significant levels of 5clc,
Fedeles adds. By comparing these levels with his team findings on how mutagenic 5clc is,
the researchers predict that accumulation of the lesions would increase the mutation rate of a cell up to 30-fold,
who was honored with the prestigious Benjamin F. Trump award at the 2015 Aspen Cancer Conference for the research.
#A new look at superfluidity MIT physicists have created a superfluid gas, the so-called Bose-Einstein condensate, for the first time in an extremely high magnetic field.
The magnetic field is a synthetic magnetic field, generated using laser beams, and is 100 times stronger than that of the world strongest magnets.
Within this magnetic field, the researchers could keep a gas superfluid for a tenth of a second just long enough for the team to observe it.
Superfluids are thought to flow endlessly, without losing energy, similar to electrons in a superconductor. Observing the behavior of superfluids
therefore may help scientists improve the quality of superconducting magnets and sensors, and develop energy-efficient methods for transporting electricity.
But superfluids are temperamental, and can disappear in a flash if atoms cannot be kept cold or confined.
to create and maintain a superfluid gas long enough to observe it at ultrahigh synthetic magnetic fields. oing to extremes is the way to make discoveries,
the John D. Macarthur Professor of Physics at MIT. e use ultracold atoms to map out
In this sense, we are ahead of nature. etterle team members include graduate students Colin Kennedy, William Cody Burton,
The electric field of the laser beams creates what known as a periodic potential landscape, similar to an egg carton,
When charged particles are exposed to magnetic fields, their trajectories are bent into circular orbits, causing them to loop around and around.
The higher the magnetic field, the tighter a particle orbit becomes. However, to confine electrons to the microscopic scale of a crystalline material,
a magnetic field 100 times stronger than that of the strongest magnets in the world would be required.
their trajectories are unaffected normally by magnetic fields. Instead, the MIT group came up with a technique to generate a synthetic
ultrahigh magnetic field, using laser beams to push atoms around in tiny orbits, similar to the orbits of electrons under a real magnetic field.
On a flat lattice, atoms can easily move around from site to site. However, in a tilted lattice, the atoms would have to work against gravity.
In this scenario, atoms could only move with the help of laser beams. ow the laser beams could be used to make neutral atoms move around like electrons in a strong magnetic field
added Kennedy. Using laser beams, the group could make the atoms orbit, or loop around, in a radius as small as two lattice squares, similar to how particles would move in an extremely high magnetic field. nce we had the idea,
we were excited really about it, because of its simplicity. All we had to do was take two suitable laser beams
Kennedy says. ew perspectives to known physicsfter developing the tilting technique to simulate a high magnetic field,
which could make them lose their superfluid properties. t a complicated experiment, with a lot of laser beams, electronics,
and keep them cold some of it was painstaking work. n the end, the researchers were able to keep the superfluid gas stable for a tenth of a second.
During that time, the team took time-of-flight pictures of the distribution of atoms to capture the topology
Those images also reveal the structure of the magnetic field something that been known, but never directly visualized until now. he main accomplishment is that we were able to verify
Ketterle says. f we can get synthetic magnetic fields under even better control, our laboratory could do years of research on this topic.
For the expert, what it opens up is a new window into the quantum world,
where materials with new properties can be studied. oing forward, the team plans to carry out similar experiments,
including quantum Hall physics and topological insulators. e are adding new perspectives to physics, Ketterle says. e are touching on the unknown,
#A bipedal robot with human reflexes Deep in the basement of MIT Building 3, a two-legged robot named HERMES is wreaking controlled havoc:
Just a few feet away, Phd student Joao Ramos stands on a platform, wearing an exoskeleton of wires and motors.
As Ramos mimes punching through a wall, the robot does the same. When the robot fist hits the wall, Ramos feels a jolt at his waist.
By reflex, he leans back against the jolt, causing the robot to rock back, effectively balancing the robot against the force of its punch.
while the robot may successfully punch through a wall, it would also fall headlong into that wall.
The interface allows a human to remotely feel the robot shifting weight, and quickly adjust the robot balance by shifting his own weight.
As a result, the robot can carry out momentum-driven tasks like punching through walls, or swinging a bat
Ramos and his colleagues envision deploying HERMES to a disaster site, where the robot would explore the area,
and his colleagues, including Phd student Albert Wang and Sangbae Kim, the Esther and Harold E. Edgerton Center Career development Assistant professor of Mechanical engineering,
a 100-pound biped robot designed by the team, along with the interface, for disaster response.
They outfitted the robot feet with load sensors that measure the force exerted by each foot on the ground.
With computer software, the researchers translated the robot center of pressure to the platform motors,
pushing a person back and forth as the robot shifts its weight. he interface works by pushing harder on the operator as the robot center of pressure approaches the edge of the support polygon,
when the hammer would strike. As Wang struck the robot, the platform exerted a similar jolt on Ramos,
In one test, the robot unexpectedly got its arm stuck in the wall. But, because the human was in the loop,
you can have the human do it. onathan Hurst, associate professor of mechanical, industrial, and manufacturing engineering at Oregon State university,
But perhaps more important than just a way to control a robot in the absence of knowing how to do it autonomously is being able to observe and collect data from the robot.
Given hours of data recording the details of human strategies for balance and pose adjustment,
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