APS News

March Meeting in New Orleans Spans Broad Range of Topics

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APS Staff
The APS March Meeting, the largest physics meeting of the year, will take place March 10-14, 2008 in New Orleans, Louisiana. More than 7,000 scientists are expected to be on hand. The principal topic areas will be condensed matter physics, industrial applications, new materials, chemical and biological physics, fluids, polymers, and computation. A number of sessions will address education, physics history, and social issues.  

SPM Turns 25. Scanning probe microscopy celebrates 25 years of cutting-edge imaging this year, and a special session at the March Meeting will focus on some of the latest innovations with this technique. Donald Eigler of IBM’s Almaden Research Center will describe how he has extended the spectroscopic abilities of the STM to enable measurement of the g-value of single atoms, with the ultimate goal building nanometer-scale binary logic circuits. Scientists at the University of Hamburg have developed a new technique called Spin-Polarized STM that has led to the discovery of new types of magnetic order at the nanoscale. Sergei Sheiko of the University of North Carolina at Chapel Hill is using SPM to image flexible polymer molecules whose overall sizes are beyond the limits of optical resolution (Session G1)

Learning from Katrina. The city of New Orleans was devastated in 2005 by Hurricane Katrina, along with several other states along the Gulf Coast. Several speakers at the APS March Meeting will discuss various aspects of the underlying science of severe hurricanes and tornadoes, as well as any possible relation to climate change. Other speakers will focus on some of the lessons learned from that disaster, in terms of mitigation and better preparation. For instance, Robert Dean of the University of Florida will review wetlands loss and possible restoration options in southern Louisiana, while Murty Akundi of Xavier University and Jim McGuire of Tulane University will share the impact of the damage on their respective campuses, and suggest improvements to academic response to future disasters. (Sessions H6, V5)

Physics in the Fast Lane. Materials physics plays a crucial role in the design and performance of both motorcycles and NASCAR vehicles. Charles Falco of the University of Arizona will discuss the inter-relationship of various technological, cultural and aesthetic factors over the last 100 years leading to high-performance motorcycles–including such new materials as carbon-fiber composites, maraging steels, and exotic alloys of magnesium, titanium and aluminum. Diandra Leslie-Pelecky of the University of Nebraska, author of the recently released book, The Physics of NASCAR, will talk about the important materials issues associated with auto racing, from safety equipment to building the cars themselves. Also featured in the session will be a talk on baseball, steroids and physics by Tufts University’s Roger Tobin, and James Kakalios, a  hysics professor at the University of Minnesota and author of The Physics of Superheroes. (Session D3)

Optical Lattices for Quantum Computing. Quantum computing just got one stop closer with an advance in optical lattice technology. David Weiss (Penn State) will describe a 3D optical lattice partially filled with individual atoms at 250 sites. Ultimately, Weiss and his colleagues hope to use the atoms as qubits in a quantum computer. Unlike previous 3D lattices, the spacing between the atoms in the new system is large enough that the atoms can be individually manipulated with lasers and microwaves without disturbing neighboring atoms. The atoms’ individual addressability and the fact that the atoms have multiple neighbors to quantum mechanically interact with make the system a promising route to quantum computing. (B6.4)

Gold, Tin and Lead Buckyballs. Carbon buckyballs (fullerenes) are tiny spherical clusters of carbon atoms. The structures were first identified in 1985. But it was only two years ago that Lai-Sheng Wang (Washington State University and Pacific Northwest National Laboratory) and colleagues found that gold atoms could form similar spherical arrangements. Last year, Wang and his research group expanded the list of buckyball-forming elements by showing that tin and lead atoms could form into tiny spherical clusters, which they have respectively designated stannaspherene and plumbaspherene. Fullerenes are important in part because their properties can be adjusted by trapping other atoms at the center of the atomic cages. But some important elements interact strongly with gold and can’t be trapped inside golden fullerenes, which limits the structure’s potential for chemical applications. Tin fullerenes, on the other hand, can accommodate a number of important transition metal atoms and may end up being the most chemically versatile form of fullerenes discovered so far. (B21.5)

Artificial Neurons. The biophysics of neurons helps us understand how the brain works and suggests that artificial neurons may someday help in repairing or replacing damaged nerves. Donald Edwards (Georgia State University) will open session Y36, which is dedicated to various aspects of artificial neurons, with a look at a new software package called AnimatLab that allows researchers to construct models of neural circuits and test their ability to mimic the movements of living creatures. Specific examples of AnimatLab studies will be presented by David Cofer (Georgia State University) in a talk about the mechanics of locust jumping (Y36.2) and Alexander Klishko (Georgia Tech), who has studied the extremely high accelerations cats’ paws achieve when shaking in response to an irritating stimulus (A38.7). In talk Y36.7, Ranu Jung (Arizona State University) presents recent work on interfacing artificial neurons with damaged nerves in attempts to create neuroprosthetics.  Other talks in the session describe a robot designed to mimic the locomotion of sea lampreys (Nikolai Rulkov, University of California, San Diego, Y36.3) and new ways to analyze neuronal activity (Y36.4, Y36.5, Y36.8, and Y36.11).

The Econophysics of Epidemics. Understanding human mobility patterns can help improve urban planning and traffic forecasting, as well as help prevent the spread of diseases. Scientists at Notre Dame University and Northeastern University have tracked the individual mobility pattern of cell phone users and time-resolved the data, and have come up with a new model for a universal mobility pattern. In the same session, researchers from the College of William and Mary will present their findings on the dynamics of epidemic spread, focusing on multistrain diseases (such as dengue fever and Ebola) with a high risk of secondary infection by a different strain. Also, scientists from the Max-Planck Institute for Dynamics and Self-Organization in Goettingen, Germany, have modeled the dynamics of panic reactions: how infectious wave front dynamics are affected as people disperse more widely to avoid infection. (Papers D39.3, D39.4, D39.5)

Circuit QED. Quantum electrodynamics (QED) is the most precise theory in all of physics, allowing tests of theory with experimental findings to levels of a part in a trillion or better. One sub-category of research is cavity-QED, in which the arena is a tiny cavity where basic interactions between atoms and photons, or photons alone, can be studied with great care. Recently a group of physicists at Yale in the group of Rob Schoelkopf accomplished two important feats that might help in the important endeavor to produce and process quantum bits (qubits) for future computers that handle quantum information. First, they produced a reliable source of single microwave photons; producing such photons by the million is easy, but not so easy if you want to make them singly on command. Second, they were able to transfer quantum information from one qubit to another along a wire; to be more precise the wire guided the photon (a virtual photon) from one place on a chip to another, the wire acting as a sort of common bus for moving information. The qubits (in effect bits consisting of a superpositions of both 0s and a 1s) reside in the form of the presence (or absence) of a single photon in a tiny cavity. Now, Johannes Majer (recently moved from Yale to the Vienna University of Technology) will report on progress of coupling superconducting qubits via a quantum bus. (Paper D5.3)

Toward Gigabar Pressures. Several sessions and a town meeting of practitioners will address the subject of producing ultrahigh pressures in laboratories or in simulating the effects of high pressure on various materials. Generally megabar (106 atm) pressures can be produced in the lab using either static pressure produced in a tiny anvil cell employing the facets of diamonds (up to about 5 megabar) or dynamic pressure produced in the form of shock waves. Laser driven shocks currently produce pressures in the tens of megabar (1 tera-pascal) range, but within a few years gigabar pressures will be accessible with lasers at the National Ignition Facility (NIF) in the US and the Laser MegaJoule (LMJ) facility in France. Raymond Jeanloz of UC Berkeley will report on studies of liquid diamond (diamonds melted by laser light), which is metallic in nature. Jeanloz makes the point that the megabar pressures at work squeezing a material are equivalent to electron-volt-levels changes in the strengths of chemical bonding among neighboring atoms. In effect, he says, the periodic table properties of atoms are fundamentally altered by megabar pressures. All of this is magnified at gigabar pressures (equivalent to keV changes in bonding), where core-electrons, normally very reticent inside their atoms, become participants in the chemistry. (Paper T16.2)

Nanoparticles Kill Tumors In Rats. The ability to deliver drugs specifically to one part of the brain or some other specific tissue in the body is highly desirable in diseases like cancer, where the drugs may have widespread toxicity to healthy cells throughout the body. One nanotechnology-based approach to solving this problem was designed about 10 years ago by Raoul Kopelman (University of Michigan). Kopelman found a way of making tiny polyacrylamide particles about 60 nanometers in diameter that can be imbedded with drugs or other compounds and safely delivered to the bloodstream. Moreover, antibodies or other “targeting” molecules can be attached to the outside of the particles so that they can ferry this payload though the body and dock at the tissues where the drugs are needed. In his talk, Kopelman describes one experiment where he and his colleagues decorated these particles with peptides that helped guide them into the nuclei of cancer cells in the brain, There, MRI contrast agents loaded in these nanoparticles helped image the tumor cells, and when illuminated by a laser, photodynamic chemicals inside the nanoparticles released highly-reactive singlet oxygen into the cancer cells, killing them. One 5-minute blast with simple red laser cured a few rats of glioblastoma, one particularly nasty form of brain cancer.  (X15.2)

Micro-Ocean. An important part of the biosphere is the population of micro-organisms, which stand at the lowest level of the food chain but which dominate all others in terms of mass. At his MIT lab, Roman Stocker looks at such micro societies in ecological landscapes created on micro-fluidic chips. To marine bacteria, the ocean is a desert, a place where nutrients are scarce. Stocker will report on surprising signs that bacteria are much more efficient than was previously thought in their search for patches of nutrients. This might be an important step in studying how carbon and carbon dioxide are taken up in the ocean.  (Paper P6.4)

Record-Setting Subwavelengh Image Transmission. As a rule, images manipulated with lenses and mirrors cannot reveal details smaller than half the wavelength of light used to transmit them. Recently, many research groups have tried to break the resolution limit with new optical devices. Pavel Belov (Queen Mary University of London) and colleagues appear to have captured the subresolution flag with a system that can produce images with resolutions fifteen times smaller than the wavelength of the light used to create them, and transmit the images over distances 3.5 times the light’s wavelength. The record was set with an array of parallel metallic rods that can be manufactured to work for wavelengths ranging from microwaves to mid-infrared light. Belov will report on the performance of the novel subwavelength system and discuss the potential for image magnification, data storage and other applications. (V28.5)

Switch Alternatives for Microelectronics. Miniaturization is the primary focus of most efforts to advance the state of the art in microelectronics. An added benefit of shrinking devices is that energy efficiency tends to improve dramatically as well, with one notable exception–even at tiny dimensions transistors are power-hungry components. Session S2 focuses on the increasing importance of finding alternatives to transistors in microelectronics. Eli Yablonovitch (University of California, Berkeley) will start the session off by considering a number of low voltage alternatives to transistors. Among the other speakers in the invited session, Joerg Appenzeller (Purdue) will consider solid state carbon nanotube devices, and Marc Baldo (MIT) will describe a prototype nanoscopic mechanical switch (also built of carbon nanotubes) that has the potential to eliminate losses characteristic of transistors, operate at low voltages, and run at much higher temperatures than typical of many silicon-based devices. (Session S2)

Solar Cells: The Next Generation. More silicon goes into the making of solar cells than into the making of microchips. Although accounting for only a tiny portion of overall electricity generation so far, solar cells are moving up quickly. For the past five years the amount of solar-generated electricity has increased by about 40% per year. Mass production of solar panels will help immensely in the overall long-term goal of bringing the cost of solar electricity down closer to that of coal-fired electricity. In the meantime, the things physicists can do are to explore new ways to make the cells more efficient and cheaper to produce. Session L2 is devoted to this effort. For example, one paper will consider the use of silicon nanocrystallites rather than more cumbersome (and expensive) single-crystal configurations used in present cells. Making cells from dye-sensitized paint components (titanium dioxide particles) is another route to cost reduction; the cells are somewhat less efficient than Si cells but are really cheap. Another paper looks at the use of quantum dots for utilizing solar radiation at certain infrared wavelengths that would otherwise be lost to the conversion process. One speaker will report on the use of high-efficiency (and more expensive) tandem solar cells and the use of concentrators to focus sunlight and reduce the cost. The issue of high efficiency is especially crucial for portable solar-powered devices that are being developed by the military for use by soldiers in the battlefield. (Session L2)

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