I Don't Believe in God, But I Pray

 

Being free of God doesn't mean I have to be free of hope.

Shutterstock

A few coins lay at the patinated feet of a statue of St. Jude outside a Roman Catholic church in Brooklyn. The patron saint of desperate cases and hopeless causes stands silent as those wrestling with life dominating addictions enter one of the many Alcoholics Anonymous meetings hosted in the church's basement. 

Even though society at large has grown increasingly secular since the 1960's, inside this enclave many will encourage each other to fortify their sobriety through hitting their knees in prayer to God.

Yet some members, like "John," 43, and in his fifteenth year of recovery from addiction to drugs and alcohol, are sharing a new slogan:

"I don't believe in god, but I pray."

Alcoholics Anonymous has a long-standing tradition of using prayer as a means of combating addiction. Bill Wilson, the founder of AA., was greatly influenced by the Oxford Group, a fundamentalist Christian movement that emphasized "God-Controlled" living through prayer. Wilson ascribes his being relieved from late stage chronic alcoholism to the power of a divine being he maintained communion with through prayer over the 37 years of his sobriety.

Yet since its early days, AA has had a minority voice advocating a secular understanding of sobriety. Jim Burwell, a self-described "militant agnostic" and one of the first ten members of Alcoholics Anonymous, was instrumental in the formulation of the society's third tradition, a guiding principle which states, "the only requirement for membership is a desire to stop drinking" - not belief in God or prayer.

While some contemporary freethinkers, atheists, and agnostics who don't believe in prayer are choosing to migrate to any of the nearly 150 secular 12 step groups in the United States, some are choosing to forge a middle path within mainstream AA. This middle path embraces a non-theistic understanding of recovery, but also advocates the traditional practice of prayer as a tool in recovery. Is this a case of bad faith or are John and those like him early adopters of an emerging understanding of prayer, one that is borne out by their own experiences?

In his hooded sweatshirt and black skinny jeans, John looks young for a man in his early middle age. A bohemian from a time when an artist could afford an entire floor of a Brooklyn loft and still have cash to spend on coke- and alcohol-fueled benders, John shrugs his shoulders with indifference when asked if his is a case of bad faith.

"I don't care if they think I'm doing it right... After ten years I realized I was doing just fine without belief in God."

Yet it wasn't always like this for John. In his early days of sobriety he was uncomfortable with the Christian inspired language of the Big Book, AA's foundational text. John had no problem with other points of emphasis within AA such as community, accountability and restitution for past harms. Yet the word "god" made him enormously uncomfortable.

"I was fearful that I would have to believe in something I didn't buy into in order to get sober."

Full of doubt and desperate to be free from his addiction to alcohol and drugs and believing AA was his only option, John threw himself into prayer despite his lack of belief in a divine higher power. Fifteen years of sobriety later, John still doesn't believe in god, but he still prays. Yet asked what he is praying to John says, "I don't have a sense that there is anything listening."

For John, prayer isn't about communion with the divine. Prayer is a vocalization of his hopes and fears, a means of releasing pent up emotions and affirming a mindset of inner peace and well-being. Although he doesn't believe in the god addressed in traditional AA supplications like the Serenity Prayer, he feels they serve a purpose in helping him stay sober.

"I feel centered by the action of prayer... They have reminders in them that put me in a mindset that typically isn't my default." 

John isn't the only one advocating the benefits of secular prayer. For "Paul," 28, an agnostic who has been sober for nearly two years, prayer is about cultivating solitude. After hitting bottom with his drinking, Paul was attracted to the pluralistic tradition of Jim Burwell within AA.

"The selling point in AA was that I didn't have to believe in God and that I could pray however I wanted to."

The son of a Presbyterian minister, prayer was a large part of his upbringing. Yet the boisterous prayers his father would offer before dinner and at the pulpit left him feeling like prayer was about pontification. Because of this, "I had a really tough time with prayer for a long time."

Yet wanting the support community that AA had to offer, he was willing to toe the line in his early sobriety, going so far as to pray on his knees next to his bed per the suggestion of his more traditional sponsor.

Yet having wrestled with his own lack of belief over the course of his sobriety, Paul came to the hard won conclusion, "I don't have a beef with word god," but I don't feel comfortable with it when it refers to a personal relationship with a divine being."

From this fidelity to self Paul's understanding of prayer grew. Now Paul prays while walking, while riding the subway and even while in the bathroom - essentially anywhere where stress which may make him vulnerable to old addictive behaviors pops up. Paul uses prayer to focus on the rhythm of his breath and clear his mind. As a result of this meditative style of prayer, Paul feels he has a significant tool at his disposal in learning to lead a sober life.

In November a first-ever agnostics and atheists in recovery convention will be held in Santa Monica, California. This may be evidence that the prevailing mode of thought within AA is shifting, but will credence be given to the experiences of those those who identify as secular, but continue to make use of prayer in recovery? Regardless of the direction AA takes in the future, John and Paul feel that in the present they are embodying, one day at a time, the motto imprinted on the anniversary medallions marking their years sober: "To thine own self be true."

Nathan Frank, art editor for the website greenpointers.com and film critic for the Bushwick Film Festival, is a New Englander writing in Brooklyn. He last wrote about picking up the pieces.

Advanced light: Sending entangled beams through fast-light materials

 

Whole beams, not just particles, can be entangled. This, plus anomalous dispersion in 'fast-light' materials, allows signals be to 'advanced' over signals travelling in vacuum, at least in a limited sense.

This image depicts the experimental setup for studying fast light. Pump beams (purple) create correlated probe (turquoise) and conjugate (gold) beams. Each of these beams is aimed at a beam splitter (yellow disks). A local oscillator (LO) also sends a laser beam into each of the beam splitters. The resulting interference pattern -- registered in a spectrum analyzer, SA -- for the probe and conjugate arms are compared.

Credit: NIST

Paul Lett and his colleagues at the Joint Quantum Institute specialize in producing modulated beams of light for encoding information. They haven't found a way to move data faster than c, the speed of light in a vacuum, but in a new experiment they have looked at how light traveling through so called "fast-light" materials does seem to advance faster than c, at least in one limited sense. They report their results (online as of 25 May 2014) in the journal Nature Photonics.

Seeing how light can be manipulated in this way requires a look at several key concepts, such as entanglement, mutual information, and anomalous dispersion. At the end we'll arrive at a forefront result.

Continuous Variable Entanglement

Much research at JQI is devoted to the processing of quantum information, information coded in the form of qubits. Qubits, in turn are tiny quantum systems -- sometimes electrons trapped in a semiconductor, sometimes atoms or ions held in a trap -- maintained in a superposition of states. The utility of qubits increases when two or more of them can be yoked into a larger quantum arrangement, a process called entanglement. Two entangled photons are not really sovereign particles but parts of a single quantum entity.

The basis of entanglement is often a discrete variable, such as electron spin (whose value can be up or down) or photon polarization (say, horizontal or vertical). The essence of entanglement is this: while the polarization of each photon is indeterminate until a measurement is made, once you measure the polarization of one of the pair of entangled photons, you automatically know the other photon's polarization too.

But the mode of entanglement can also be vested in a continuous variable. In Lett's lab, for instance, two whole light beams can be entangled. Here the operative variable is not polarization but phase (how far along in the cycle of the wave you are) or intensity (how many photons are in the beam). For a light beam, phase and intensity are not discrete (up or down) but continuous in variability.

Quantum Mutual Information

Biologists examining the un-seamed strands of DNA can (courtesy of the correlated nature of nucleic acid constituents) deduce the sequence of bases along one strand by examining the sequence of the other strand. So it is with entangled beams. A slight fluctuation of the instantaneous intensity of one beam (such fluctuations are inevitable because of the Heisenberg uncertainty principle) will be matched by a comparable fluctuation in the other beam.

Lett and his colleagues make entangled beams in a process called four-wave mixing. A laser beam (pump beam) enters a vapor-filled cell. Here two photons from the pump beam are converted into two daughter photons proceeding onwards with different energies and directions. These photons constitute beams in their own right, one called the probe beam, the other called the conjugate beam. Both of these beams are too weak to measure directly. Instead each beam enters a beam splitter (yellow disk in the drawing below) where its light can be combined with light from a local oscillator (which also serves as a phase reference). The ensuing interference patterns provide aggregate phase or intensity information for the two beams.

When the beam entanglement is perfect, the mutual correlation is 1. When studying the intensity fluctuations of one beam tells you nothing about those of the other beam, then the mutual correlation is 0.

Fast-Light Material

In a famous experiment, Isaac Newton showed how incoming sunlight split apart into a spectrum of colors when it passed through a prism. The degree of wavelength-dependent dispersion for a material that causes this splitting of colors is referred to as its index of refraction.

In most materials the index is larger than 1. For plain window glass, it is about 1.4; for water it is 1.33 for visible light, and gradually increases as the frequency of the light goes up. At much higher frequency (equivalent to shorter wavelength), though, the index can change its value abruptly and go down. For glass, that occurs at ultraviolet wavelengths so you don't ordinarily see this "anomalous dispersion" effect. In a warm vapor of rubidium atoms, however, (and especially when modified with laser light) the effect can occur at infrared wavelengths, and here is where the JQI experiment looks.

In the figure above notice that the conjugate beam is sent through a second cell, filled with rubidium vapor. Here the beam is subject to dispersion. The JQI experiment aims to study how the entanglement of this conjugate beam with the probe beam (subject to no dispersion) holds up.

When the refraction is "normal" -- that is, when index of refraction causes ordinary dispersion -- the light signal is slowed in comparison with the beam which doesn't undergo dispersion. For this set of conditions, the cell is referred to as a "slow-light" material. When, however, the frequency is just right, the conjugate beam will undergo anomalous dispersion. When the different frequency components that constitute a pulse or intensity fluctuation reformulate themselves as they emerge from the cell, they will now be just slightly ahead of a pulse that hadn't gone through the cell. (To make a proper measurement of delay one needs two entangled beams -- beams whose fluctuations are related.)

Causality

No, the JQI researchers are not saying that any information is traveling faster than c. The figure above shows that the peak for the mutual information for the fast-light-material is indeed ahead of the comparable peaks for an unscattered beam or for a beam emerging from a slow-light material. It turns out that the cost of achieving anomalous dispersion at all has been that additional gain (amplification) is needed, and this amplification imposes noise onto the signal.

This inherent limitation in extracting useful information from an incoming light beam is even more pronounced with beams containing (on average) one or less-than-one photon. Such dilute beams are desirable in many quantum experiments where measurement control or the storage or delay of quantum information is important.

"We did these experiments not to try to violate causality, said Paul Lett, "but because we wanted to see the fundamental way that quantum noise "enforces" causality, and working near the limits of quantum noise also lets us examine the somewhat surprising differences between slow and fast light materials when it comes to the transport of information."

A new way to make sheets of graphene

 

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Illustrated here is a new process for making graphene directly on a nonmetal substrate. First, a nickel layer is applied to the material, in this case silicon dioxide (SiO2). Then carbon is deposited on the surface, where it forms layers of graphene above and beneath the SiO2. The top layer of graphene, attached to the nickel, easily peels away using tape (or, for industrial processes, a layer of adhesive material), leaving behind just the lower layer of graphene stuck to the substrate.

Graphene's promise as a material for new kinds of electronic devices, among other uses, has led researchers around the world to study the material in search of new applications. But one of the biggest limitations to wider use of the strong, lightweight, highly conductive material has been the hurdle of fabrication on an industrial scale.

Initial work with the carbon material, which forms an atomic-scale mesh and is just a single atom thick, has relied on the use of tiny flakes, typically obtained by quickly removing a piece of sticky tape from a block of graphite -- a low-tech system that does not lend itself to manufacturing. Since then, focus has shifted to making graphene films on metal foil, but researchers have faced difficulties in transferring the graphene from the foil to useful substrates.

Now researchers at MIT and the University of Michigan have come up with a way of producing graphene, in a process that lends itself to scaling up, by making graphene directly on materials such as large sheets of glass. The process is described, in a paper published this week in the journal Scientific Reports, by a team of nine researchers led by A. John Hart of MIT. Lead authors of the paper are Dan McNerny, a former Michigan postdoc, and Viswanath Balakrishnan, a former MIT postdoc who is now at the Indian Institute of Technology.

Currently, most methods of making graphene first grow the material on a film of metal, such as nickel or copper, says Hart, the Mitsui Career Development Associate Professor of Mechanical Engineering. "To make it useful, you have to get it off the metal and onto a substrate, such as a silicon wafer or a polymer sheet, or something larger like a sheet of glass," he says. "But the process of transferring it has become much more frustrating than the process of growing the graphene itself, and can damage and contaminate the graphene."

The new work, Hart says, still uses a metal film as the template -- but instead of making graphene only on top of the metal film, it makes graphene on both the film's top and bottom. The substrate in this case is silicon dioxide, a form of glass, with a film of nickel on top of it.

Using chemical vapor deposition (CVD) to deposit a graphene layer on top of the nickel film, Hart says, yields "not only graphene on top [of the nickel layer], but also on the bottom." The nickel film can then be peeled away, leaving just the graphene on top of the nonmetallic substrate.

This way, there's no need for a separate process to attach the graphene to the intended substrate -- whether it's a large plate of glass for a display screen, or a thin, flexible material that could be used as the basis for a lightweight, portable solar cell, for example. "You do the CVD on the substrate, and, using our method, the graphene stays behind on the substrate," Hart says.

In addition to the researchers at Michigan, where Hart previously taught, the work was done in collaboration with a large glass manufacturer, Guardian Industries. "To meet their manufacturing needs, it must be very scalable," Hart says. The company currently uses a float process, where glass moves along at a speed of several meters per minute in facilities that produce hundreds of tons of glass every day. "We were inspired by the need to develop a scalable manufacturing process that could produce graphene directly on a glass substrate," Hart says.

The work is still in an early stage; Hart cautions that "we still need to improve the uniformity and the quality of the graphene to make it useful." But the potential is great, he suggests: "The ability to produce graphene directly on nonmetal substrates could be used for large-format displays and touch screens, and for 'smart' windows that have integrated devices like heaters and sensors."

Hart adds that the approach could also be used for small-scale applications, such as integrated circuits on silicon wafers, if graphene can be synthesized at lower temperatures than were used in the present study.

"This new process is based on an understanding of graphene growth in concert with the mechanics of the nickel film," he says. "We've shown this mechanism can work. Now it's a matter of improving the attributes needed to produce a high-performance graphene coating."

Christos Dimitrakopoulos, a professor of chemical engineering at the University of Massachusetts at Amherst who was not involved in this work, says, "This is a very significant piece of work for very large-area applications of graphene on insulating substrates." Compared to other methods, such as the use of a silicon carbide (SiC) substrate to grow graphene, he says, "The fact that the lateral size of graphene in the Hart group's approach is limited only by the size of the [CVD] reactor, instead of the size of the SiC wafer, is a major advantage."

"This is a high-quality and carefully executed work," Dimitrakopoulos adds.

The work was supported by Guardian Industries, the National Science Foundation, and the Air Force Office of Scientific Research.

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Story Source:

The above story is based on materials provided by Massachusetts Institute of Technology. The original article was written by David L. Chandler. Note: Materials may be edited for content and length.

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Journal Reference:

1. Daniel Q. McNerny, B. Viswanath, Davor Copic, Fabrice R. Laye, Christophor Prohoda, Anna C. Brieland-Shoultz, Erik S. Polsen, Nicholas T. Dee, Vijayen S. Veerasamy, A. John Hart. Direct fabrication of graphene on SiO2 enabled by thin film stress engineering. Scientific Reports, 2014; 4 DOI: 10.1038/srep05049

Social marketing at the movies

 

May 23 / 2014

Inderscience Publishers

Word-of-mouth marketing is recognized as a powerful route from long-tail sales to blockbuster, whether one is talking about the latest fishy ice cream flavor or a Hollywood romantic comedy. In the age of social media and online networking sites, such as Twitter and Facebook, the potential for spreading the word could mean the difference between consumers seeing a product as the best thing since sliced bread or the most rotten of tomatoes.

Chong Oh, Assistant Professor of Computer Information Systems at Eastern Michigan University, in Ypsilanti, Michigan, USA, has analyzed social media measures from the well-known microblogging Twitter and movie box-office data from "boxofficemojo.com ." He found that not only does activity on Twitter, which is a surrogate for, or the online equivalent of actual word-of-mouth chatter, has a direct positive effect on how many people go to see a particular movie. Not surprising given its quarter of a billion global users. Moreover, he also demonstrated on the basis of this analysis that studio-generated content and online engagement with the putative audience has an indirect effect. His research is published in the International Journal of Information Systems and Change Management.

Fundamentally, Oh's research shows that: "The more a movie studio is willing to engage with its followers via social media the more likely it is to have a higher WOM volume. This subsequently increases the likelihood of having a higher opening-weekend box office performance."

Oh cites two very different outcomes with respect to two well-known movies. The first, John Carter, is a science fiction thriller released in 2012, that lost the studio $200 million and led to the resignation of its president. By contrast, Paranormal Activity, a low-budget movie from 2009 shot in a week on a $15,000 budget grossed $107 million at the box office. These, of course, are stark outliers, there are many more, and most movies lie somewhere between these two extremes. For the marketing department ensuring that their next movie is a Paranormal rather than a Carter is partly, according to Oh, now down to online word-of-mouth.

Simply having a presence (or profile) on social media is not sufficient. "The key activity of sending outgoing tweets in the seven days leading up to the release weekend was a good indicator that correlated to word-of-mouth volume buzz about the movie," Oh reports. He has some advice for movie marketers based on the findings from this research. "Social media represent an opportunity to reach an audience and establish relationships at a personal level that traditional advertising is not capable of achieving," he explains. "Incentives to encourage more interactions such as competition or tweets from the movie's cast members should go hand-in-hand with other advertisements to pump up word-of-mouth. He also suggests the same approach to social marketing might have a similar impact in other areas, such as music sales.

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Story Source:

The above story is based on materials provided by Inderscience Publishers. Note: Materials may be edited for content and length.

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Journal Reference:

1. Chong Oh. Customer engagement, word-of-mouth and box office: the case of movie tweets. International Journal of Information Systems and Change Management, 2013; 6 (4): 338 DOI: 10.1504/IJISCM.2013.060976

Flatland optics with graphene: Smaller and faster photonic devices and circuits

 

May 23 / 2014

Basque Research

Researchers have introduced a platform technology based on optical antennas for trapping and controlling light with the one-atom-thick material graphene. The experiments show that the dramatically squeezed graphene-guided light can be focused and bent, following the fundamental principles of conventional optics. The work opens new opportunities for smaller and faster photonic devices and circuits.

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nanoGUNE.

Researchers from CIC nanoGUNE, in collaboration with ICFO and Graphenea, introduce a platform technology based on optical antennas for trapping and controlling light with the one-atom-thick material graphene. The experiments show that the dramatically squeezed graphene-guided light can be focused and bent, following the fundamental principles of conventional optics. The work, published yesterday in Science, opens new opportunities for smaller and faster photonic devices and circuits.

Optical circuits and devices could make signal processing and computing much faster. "However, although light is very fast it needs too much space," explains Rainer Hillenbrand, Ikerbasque Professor at nanoGUNE and UPV/EHU. In fact, propagating light needs at least the space of half its wavelength, which is much larger than state-of-the-art electronic building blocks in our computers. For that reason, a quest for squeezing light to propagate it through nanoscale materials arises.

The wonder material graphene, a single layer of carbon atoms with extraordinary properties, has been proposed as one solution. The wavelength of light captured by a graphene layer can be strongly shortened by a factor of 10 to 100 compared to light propagating in free space. As a consequence, this light propagating along the graphene layer -- called graphene plasmon -- requires much less space.

However, transforming light efficiently into graphene plasmons and manipulating them with a compact device has been a major challenge. A team of researchers from nanoGUNE, ICFO and Graphenea -- members of the EU Graphene Flagship -- now demonstrates that the antenna concept of radio wave technology could be a promising solution. The team shows that a nanoscale metal rod on graphene (acting as an antenna for light) can capture infrared light and transform it into graphene plasmons, analogous to a radio antenna converting radio waves into electromagnetic waves in a metal cable.

"We introduce a versatile platform technology based on resonant optical antennas for launching and controlling of propagating graphene plasmons, which represents an essential step for the development of graphene plasmonic circuits," says team leader Rainer Hillenbrand. Pablo Alonso-González, who performed the experiments at nanoGUNE, highlights some of the advantages offered by the antenna device: "the excitation of graphene plasmons is purely optical, the device is compact and the phase and wavefronts of the graphene plasmons can be directly controlled by geometrically tailoring the antennas. This is essential to develop applications based on focusing and guiding of light."

The research team also performed theoretical studies. Alexey Nikitin, Ikerbasque Research Fellow at nanoGUNE, performed the calculations and explains that "according to theory, the operation of our device is very efficient, and all the future technological applications will essentially depend upon fabrication limitations and quality of graphene."

Based on Nikitin´s calculations, nanoGUNE's Nanodevices group fabricated gold nanoantennas on graphene provided by Graphenea. The Nanooptics group then used the Neaspec near-field microscope to image how infrared graphene plasmons are launched and propagate along the graphene layer. In the images, the researchers saw that, indeed, waves on graphene propagate away from the antenna, like waves on a water surface when a stone is thrown in.

In order to test whether the two-dimensional propagation of light waves along a one-atom-thick carbon layer follow the laws of conventional optics, the researchers tried to focus and refract the waves. For the focusing experiment, they curved the antenna. The images then showed that the graphene plasmons focus away from the antenna, similar to the light beam that is concentrated with a lens or concave mirror.

The team also observed that graphene plasmons refract (bend) when they pass through a prism-shaped graphene bilayer, analogous to the bending of a light beam passing through a glass prism. "The big difference is that the graphene prism is only two atoms thick. It is the thinnest refracting optical prism ever," says Rainer Hillenbrand. Intriguingly, the graphene plasmons are bent because the conductivity in the two-atom-thick prism is larger than in the surrounding one-atom-thick layer. In the future, such conductivity changes in graphene could be also generated by simple electronic means, allowing for highly efficient electric control of refraction, among others for steering applications.

Altogether, the experiments show that the fundamental and most important principles of conventional optics also apply for graphene plasmons, in other words, squeezed light propagating along a one-atom-thick layer of carbon atoms. Future developments based on these results could lead to extremely miniaturized optical circuits and devices that could be useful for sensing and computing, among other applications.

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Story Source:

The above story is based on materials provided by Basque Research. Note: Materials may be edited for content and length.

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Journal Reference:

1. P. Alonso-Gonzalez, A. Y. Nikitin, F. Golmar, A. Centeno, A. Pesquera, S. Velez, J. Chen, G. Navickaite, F. Koppens, A. Zurutuza, F. Casanova, L. E. Hueso, R. Hillenbrand. Controlling graphene plasmons with resonant metal antennas and spatial conductivity patterns. Science, 2014; DOI: 10.1126/science.1253202

Chip produces and detects specialized gas for biomedical analysis

 

May 22 / 2014

National Institute of Standards and Technology (NIST)

A chip-scale device that both produces and detects a specialized gas used in biomedical analysis and medical imaging has been built and demonstrated. The new microfluidic chip produces magnetized xenon gas and then detects even the faintest magnetic signals from the gas. Magnetized xenon can be used as a marker for detecting biomolecules in liquids. Conventional systems for producing and using this gas can be as big as a car.

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This is an illustration of a NIST chip that makes polarized xenon gas. Xenon atoms (green) are loaded into the chamber on the left. The xenon flows into the next chamber, where the atoms are polarized through collisions with rubidium atoms (red) that are illuminated with circularly polarized light. Then the xenon flows into the smaller chamber, where its polarization is measured, using the rubidium atoms in the same chamber as magnetometers. Atoms exit the chip from the chamber on the far right.

A chip-scale device that both produces and detects a specialized gas used in biomedical analysis and medical imaging has been built and demonstrated at the National Institute of Standards and Technology (NIST). Described in Nature Communications, the new microfluidic chip produces polarized (or magnetized) xenon gas and then detects even the faintest magnetic signals from the gas.

Polarized xenon -- with the atoms' nuclear "spins" aligned like bar magnets in the same direction -- can be dissolved in liquids and used to detect the presence of certain molecules. A chemical interaction with target molecules subtly alters the magnetic signal from the xenon; by detecting this change researchers can identify the molecules in a complex mixture. Polarized xenon is also used as a contrast agent to enhance images in experimental magnetic resonance imaging (MRI) of human lungs, but conventional systems for producing and using this gas can be as big as a car.

Researchers from NIST and three other institutions developed the new chip, which might be used to reduce the size and cost of some instruments that, like MRI, rely on nuclear magnetic resonance (NMR). The chip's sensitive internal detector boosts the response of microfluidic NMR on small samples and eliminates the need for the powerful magnets associated with larger NMR devices such as those used in MRI. The microfabricated chip could be mass produced and integrated easily with existing microfluidic systems.

"We envision this device being an element in a more complex microfluidic NMR system, maybe for medical diagnostics," NIST physicist and co-author John Kitching says.

The new device is related to NIST's chip-scale magnetometer but has additional capabilities and different applications, Kitching notes. Like the older NIST device, the new chip uses rubidium atoms as magnetometers to detect the xenon polarization, but they also multitask. The novel design also uses the rubidium atoms to polarize the xenon atoms, boosting their NMR response, and mixes the two types of atoms in the same chamber at the detection stage, which enhances the signal strength 500-fold.

The device is housed in a silicon and glass chip about 3centimeters long with four small chambers connected by microchannels. In one chamber, circularly polarized light transfers angular momentum to the rubidium atoms' electrons. The rubidium atoms then exchange spin with the nuclei of the xenon atoms, enhancing their polarization and hence the NMR signal.

The polarized xenon and rubidium atoms then flow into a detection chamber. Thanks to the atoms' magnetic interactions the sensor can detect weak signals corresponding to fewer than 1 trillion polarized xenon atoms, a result competitive with low-field optical magnetometry.

The combination of a xenon polarizer and detector in the same device, together with the extraordinary sensitivity of the chip device, could help make polarized xenon technology portable and less expensive for biomedical and other applications outside research laboratories.

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Story Source:

The above story is based on materials provided by National Institute of Standards and Technology (NIST). Note: Materials may be edited for content and length.

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Journal Reference:

1. Ricardo Jiménez-Martínez, Daniel J. Kennedy, Michael Rosenbluh, Elizabeth A. Donley, Svenja Knappe, Scott J. Seltzer, Hattie L. Ring, Vikram S. Bajaj, John Kitching. Optical hyperpolarization and NMR detection of 129Xe on a microfluidic chip. Nature Communications, 2014; 5 DOI: 10.1038/ncomms4908

NCNR neutrons highlight possible battery candidate

 

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At the top of this image, sodium fills in layers of the crystal, represented by one bright yellow dot followed by three darker ones; at bottom, the layers' magnetic ordering is shown as green and purple dots representing magnesium at two different charge states, with the green-in-purple dots representing a mixture of the two charge states. Artwork generated from a scanning tunneling microscope image.

Analysis of a manganese-based crystal by scientists at the National Institute of Standards and Technology (NIST) and the Massachusetts Institute of Technology (MIT) has produced the first clear picture of its molecular structure. The findings could help explain the magnetic and electronic behavior of the whole family of crystals, many of which have potential for use in batteries.

The family of crystals it belongs to has no formal name, but it has three branches, each of which is built around manganese, cobalt or iron -- transition metals that can have different magnetic and charge properties. But regardless of family branch, its members share a common characteristic: They all store chemical energy in the form of sodium, atoms of which can easily flow into and out of the layers of the crystal when electric current is applied, a talent potentially useful in rechargeable batteries.

Other members of this family can do a lot of things in addition to energy storage that interest manufacturers: Some are low-temperature superconductors, while others can convert heat into electricity. The trouble is that all of them are, on the molecular level, messy. Their structures are so convoluted that scientists can't easily figure out why they do what they do, making it hard for a manufacturer to improve their performance.

Fortunately, this particular manganese crystal is an exception. "It's the one stable compound we know of in the manganese branch that has a perfect crystal lattice structure," says Jeff Lynn of the NIST Center for Neutron Research (NCNR). "That perfection means we can isolate all its internal electronic and magnetic interactions and see them clearly. So now, we can start exploring how to make those sodium atoms more movable."

Team members from MIT made the material and performed analysis using state-of-the-art lab techniques such as electron microscopy, but they needed help from the NCNR's neutron beams to tease out the interactions between its individual atoms. The effort showed that the crystal was unusual for reasons beyond its structural perfection. Its layers absorb sodium in a fashion rarely seen in nature: In each layer, one "stripe" of atoms fills up completely with sodium, then the next three stripes fill up only halfway before another full stripe appears. Lynn says the pattern is caused by different charges and magnetic moments that manganese atoms possess in different parts of the crystal, a feature revealed by analysis of the NCNR data.

"This particular crystal is probably not the one you'd use in a battery or some other application, it just permits us to understand what's happening with its internal structure and magnetism for the first time," Lynn says. "Now we have a basis for tailoring the properties of these materials by changing up the transition metals and changing the sodium content. We no longer have to hunt around in the dark and hope."

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Story Source:

The above story is based on materials provided by National Institute of Standards and Technology (NIST). Note: Materials may be edited for content and length.

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Journal Reference:

1. Xin Li, Xiaohua Ma, Dong Su, Lei Liu, Robin Chisnell, Shyue Ping Ong, Hailong Chen, Alexandra Toumar, Juan-Carlos Idrobo, Yuechuan Lei, Jianming Bai, Feng Wang, Jeffrey W. Lynn, Young S. Lee, Gerbrand Ceder. Direct visualization of the Jahn–Teller effect coupled to Na ordering in Na5/8MnO2. Nature Materials, 2014; 13 (6): 586 DOI: 10.1038/nmat3964

Don't blink! Why quantum dots suffer from 'fluorescence intermittency' and may be trouble for potential quantum Internet

 

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Experimental apparatus used to investigate quantum dot blinking. A quantum dot is optically excited using a laser and its fluorescence is collected ...

Researchers at the National Institute of Standards and Technology (NIST), working in collaboration with the Naval Research Laboratory, have found that a particular species of quantum dots that weren't commonly thought to blink, do.

So what? Well, although the blinks are short -- on the order of nanoseconds to milliseconds -- even brief fluctuations can result in efficiency losses that could cause trouble for using quantum dots to generate photons that move information around inside a quantum computer or between nodes of a future high-security internet based on quantum telecommunications.

Beyond demonstrating that the dots are blinking, the team also suggests a possible culprit.

Scientists have regarded indium arsenide and gallium arsenide (InAs/GaAs) quantum dots to be promising as single photon sources foruse in different future computing and communication systems based on quantum technologies. Compared to other systems, researchers have preferred these quantum dots because they appeared to not blink and because they can be fabricated directly into the types of semiconductor optoelectronics that have been developing over the past few decades.

The NIST research team also thought these quantum dots were emitting steady light perfectly, until they came upon one that was obviously blinking (or was "fluorescently intermittent," in technical terms). They decided to see if they could find others that were blinking in a less obvious way.

While most previous experiments surveyed the dots in bulk, the team tested these dots as they would be used in an actual device. Using an extremely sensitive photon autocorrelation technique to uncover subtle signatures of blinking, they found that the dots blink over timescales ranging from tens of nanoseconds to hundreds of milliseconds. Their results suggest that building photonic structures around the quantum dots -- something you'd have to do to make many applications viable -- may make them significantly less stable as a light source.

"Most of the previous experimental studies of blinking inInAs/GaAs quantum dots looked at their behavior after the dots have been grown but before the surrounding devices have been fabricated," says Kartik Srinivasan, one of the authors of the study. "However, there is no guarantee that a quantum dot will remain non-blinking after the nanofabrication of a surrounding structure, which introduces surfaces and potential defects within 100 nanometers of the quantum dot. We estimate the radiative efficiency of the quantum dots to be between about 50 and 80 percent after the photonic structures are fabricated, significantly less than the 100 percent efficiency that future applications will require."

According to Marcelo Davanço, another author of the study, future work will focus on measuring dots both before and after device fabrication to better assess whether the fabrication is indeed a source of the defects thought to cause the blinking. Ultimately, the authors hope to understand what types of device geometries will avoid blinking while still efficiently funneling the emitted photons into a useful transmission channel, such as an optical fiber.

The NIST Center for Nanoscale Science and Technology (CNST) is a national nanotechnology user facility that enables innovation by providing rapid access to the tools needed to make and measure nanostructures. Researchers interested in accessing the techniques described here or in collaborating on their future development should contact Kartik Srinivasan.

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Story Source:

The above story is based on materials provided by National Institute of Standards and Technology (NIST). Note: Materials may be edited for content and length.

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Journal Reference:

1. Marcelo Davanço, C. Stephen Hellberg, Serkan Ates, Antonio Badolato, Kartik Srinivasan. Multiple time scale blinking in InAs quantum dot single-photon sources. Physical Review B, 2014; 89 (16) DOI: 10.1103/PhysRevB.89.161303

Chemistry behind BBQ

 

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It's that time of the year again when people are moving their kitchens outside in order to soak up the warm weather and smoky aromas of grilling. IFT spokesperson Guy Crosby, PhD, CFS provides insight into the food science behind BBQ. Crosby addresses how a marinade works to keep your meat tender, how smoking can infuses new flavors into meat, searing and more.

1. How does using a marinade make meat tenderer?

There are some misconceptions around this topic, typically only salt or salty ingredients such as soy sauce make the biggest difference. It really depends on the type of meat and the muscle structure. The protein that forms when the salt breaks the muscle down helps to retain moisture, and makes the tissue a little looser.

Acid-based marinades such as lime, lemon juice or vinegar don't have a huge effect. They will help break down some connective tissue and flavor the meat, but it's really only on the surface.

2. Does searing a meat before cooking help keep the juices inside?

Searing does not trap or keep moisture inside a piece of meat; it's an old kitchen myth.

3. Why does a piece of meat need to rest before cutting it?

When you cook meat the muscle fibers and the proteins begin to shrink and squeeze out moisture. If you immediately slice a piece of meat, the moisture that has been squeezed out of the muscle fibers will run out. But if you let it sit for 15 to 20 minutes depending on the size and thickness of the meat, the fibers start to soak back up some of that moisture.

4. What is the Maillard Reaction?

A French scientist in 1912 discovered certain proteins and amino acids react with certain kinds of sugars and cause browning. When meat is browned it forms hundreds of very potent flavor molecules that affect its aroma and taste.

5. Why cook low and slow?

The lower you cook the temperature, the less the fibers will shrink, the less tough the meat will be because it won't lose as much moisture. Typically tough cuts of meat are cooked this way to keep the meat moist. Cooking the meat slowly breaks down tough connective tissue to form gelatin, which binds moisture. The amount of fat also helps because it breaks up the protein, lubricates the meat and makes it tenderer.

6. When smoking a piece of meat, how does the wood flavor get infused into it?

The oxygen breaks down the lignin in wood and releases a smoky aroma that sticks to the moist surface of the meat, flavoring it.

7. What is an easy thickening agent to use at home to thicken a BBQ sauce?

The most common one would be cornstarch. The best way is to add cornstarch to room temperature water first, mix well, and then add the combination to the sauce and heat. Flour is another option.

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Story Source:

The above story is based on materials provided by Institute of Food Technologists (IFT). Note: Materials may be edited for content and length.

New method for propulsion in fluids: Researchers discover a way for temperature gradients in fluids to move objects

 

This wedge-shaped device was used for laboratory tests of the propulsion system based on thermal differences. One of the bottom edges of the device can be heated using internal heaters, activated by a remote control.

Researchers at MIT have discovered a new way of harnessing temperature gradients in fluids to propel objects. In the natural world, the mechanism may influence the motion of icebergs floating on the sea and rocks moving through subterranean magma chambers.

The discovery is reported this week in the journal Physical Review Letters by associate professor of mechanical engineering Thomas Peacock and four others. The finding was an unexpected outcome of research on other effects of temperature differences, such as the way winds form over glaciers in a valley, Peacock says.

These winds are generated by natural convection that arises from temperature differences between a fluid and a heated or cooled boundary. "People had only ever studied this phenomenon in relation to a fixed object," Peacock says. But his group realized that "if you can induce these kinds of flows on the boundaries of a floating object, you can generate forces."

Peacock's first study of the concept, about four years ago, focused on slow flows caused by diffusion -- work that demonstrated that induced boundary flows can generate small propulsive forces. But diffusion is a very gradual process, he says, and the resulting forces are perhaps too small to be exploited.

"I always thought, and expected, that the equivalent flows you could generate by selective heating and cooling of an object could be more significant," Peacock says.

But perfecting the experimental setup was challenging. Fully calming a floating object and tank of water before beginning a test and devising a way to heat the object without causing ripples or movement were particularly difficult tasks. The team decided to use a metal wedge, about 5 inches long, containing a heating element that could be activated by a remote control unit.

This experiment was the first to demonstrate that a temperature differential between the surface of an object and the surrounding fluid can drive movement -- an effect that might have widespread significance in the natural world, and potential for future technologies.

The effect itself is surprisingly simple, Peacock explains: "By virtue of heating or cooling the surface of an object, you change the density of any fluid next to that surface." In the valley winds previously considered, the object was either a glacier or a valley wall heated by the sun, and the fluid was the air passing over it; in this case, it's the solid wedge and its surrounding water.

The changed density of the fluid generates a flow over the surface, Peacock says, adding, "That flow then creates unbalanced forces, with lower pressure on one side, and higher on the other" -- an imbalance that propels the object from the higher pressure toward the lower.

The phenomenon applies to "any situation where an object is immersed in fluid, and its temperature is different" from that of the fluid, Peacock says.

The basic equations that govern convection are well known, Peacock says. "This type of flow has been studied for over 100 years, but somehow, in all that time, no one had thought to do this."

Peacock is already working on such follow-up experiments, to figure out "whether the effect can be exploited, in an engineering sense, and also whether nature might already be exploiting it."

The method could prove useful in controlling how particles move through microfluidic devices, or in understanding the motion of material floating in magma. It may, Peacock says, even turn out to be something that living organisms have learned to harness: If a very small creature can propel itself by selectively heating or cooling itself, that could turn out to be a significant mechanism, he says.

"It's very rare in fluid mechanics to discover a new phenomenon like this," Peacock says. "There are so many fields that this could potentially impact. … I hope other researchers will hear about the effect and investigate it in their particular fields and discover new things."

In addition to Peacock, the work was carried out by former MIT postdoc Matthieu Mercier, now at the Institut de Mécanique des Fluides de Toulouse in France; MIT affiliates Brian Doyle and Michael Allshouse; and Arezoo Ardekani, now a faculty member at the University of Notre Dame.