Sigma Xi Distinguished Lecturers 2003-2004 Abstracts
Thomas R. Albrecht
The Disk Drive: Unsung Hero of the Technology Revolution (Public audience)
When we think of the technology building blocks behind the revolution in computers that has occurred over the last half century, silicon microchips, or integrated circuits, are often viewed as the technology that made it all possible. While the rapid progress in integrated circuits is known by the now-famous "Moore's Law" (which states that the number of transistors on a microchip doubles about every 18 months), a lesser known fact is that an analogous figure of merit for disk drives, the "areal density" (number of data bits stored per square inch of disk real estate) of disk drives is rising even faster. The technology in disk drives which makes all this possible draws on a variety of scientific disciplines perhaps a wider variety than any other type of device associated with computers. For starters, disk drives are inherently mechanical devices, and invoke precision mechanics on a seemingly unimaginable scale. Consider, for example, that the read/write head in a disk drive, which floats on a cushion of air over the spinning disks, hover at a height of only 20 nanometers (that's equivalent to the space required for just 60 atoms, or about 1 million times less than the thickness of a human hair), while the disk spins at speeds up to 100 miles per hour. Other aspects of disk drives rely on cutting edge advances in chemistry, materials science, physics, and electrical engineering. This presentation will explore in everyday language how these technologies work together in disk drives to allow us to store tens of gigabytes of information very inexpensively, and how such vast amounts of inexpensive data storage are changing the experience of using computers and other devices (such as video recorders, music players, and cameras) that use disk drives.
Magnetic Recording: Winner of the Data Storage Technology Race (General audience)
Among the technologies responsible for the revolution in the information processing industry in the last half of this century, magnetic recording stands out as one of the most prominent examples of rapid performance improvement and cost reduction. The pace of improvement in magnetic recording compares favorably with that of microprocessors and memory technologies, with recording densities currently growing by 60-100% per year. Although various technologies have been predicted to replace magnetic recording (e.g., optical recording, solid-state storage, and holography), continuing rapid advances have maintained magnetic recording's advantages over competing technologies. Hard disk drives, which are the most commonly used form of magnetic data storage, contain an advanced mix of mechanical and electronic technologies, and exploit advanced materials. This presentation will explore some of the technologies that have made such rapid advances in magnetic recording possible, and examine the extent to which the present pace of improvement can be sustained into the future. Continuing improvement requires the industry to overcome multiple technical challenges that appear to be more difficult than those encountered over the past few decades. Just as challenges in semiconductor technology are expected to slow future progress in processors and electronic memory, disk drive advances show similar signs of slowing down. This presentation will also examine how the vast amount of inexpensive data storage in today's disk drives has transformed the experience of using computers, and how disk drives are beginning to appear in a variety of other devices that affect our daily lives, including cameras, audio players, and video recorders. While the spread of disk drives to realms outside the traditional computer industry has been driven mainly by rapidly decreasing costs, it has also been aided by miniaturization of disk drives. At the forefront of such miniaturization are tiny "microdrives" that store up to a gigabyte of data in a matchbook-size device.
Magnetic Recording: Winner of the Data Storage Technology Race (Specialized audience)
Among the technologies responsible for the revolution in the information processing industry in the last half of this century, magnetic recording stands out as one of the most prominent examples of rapid performance improvement and cost reduction. The pace of improvement in magnetic recording compares favorably with that of microprocessors and memory technologies, with recording densities currently growing by 60-100% per year. Although various technologies have been predicted to replace magnetic recording (e.g., optical recording, solid-state storage, and holography), continuing rapid advances have maintained magnetic recording's advantages over competing technologies. Hard disk drives, which are the most commonly used form of magnetic data storage, contain an advanced mix of mechanical and electronic technologies, and exploit advanced materials. The head-disk interface requires surfaces with nanometer-scale roughness and flatness, advanced air bearings which fly at heights less than 20 nm at velocities greater up to 50 m/sec, and durable lubricants and overcoats to prevent interface degradation even in harsh environments (extremes in temperature, humidity, barometric pressure, and shock). Data track widths on the order of 1 um require low-runout spindles and high bandwidth servo, actuator, and suspension designs. Read/write transducers exploit a newly discovered physical effect ('giant magnetoresistance') and employ esoteric magnetic thin-film fabrication techniques coupled with highly accurate bulk machining and polishing methods. Low-noise disk media for high density recording require finely controlled grain size and coupling. To continue the rapid pace of improvement, the disk drive industry must meet challenges and adopt major technical changes during the coming few years. These transitions include possible adoption of magnetic tunnel junction sensors, perpendicular recording, dual-stage actuators with microfabricated actuator elements, contact recording, improved start/stop technologies such as load/unload, fluid bearing spindle motors, and new classes of disk materials to avoid spontaneous thermal decay of written data patterns at densities greater than 50 Gbit/square inch (where the "superparamagnetic effect" becomes significant). In addition, the industry is taking on the challenge of applying magnetic data storage to new markets, such as consumer electronics and handheld/portable systems. An example of a new product addressing the latter market segment is IBM's newly introduced "microdrive" (a matchbook-size drive in a CompactFlash card with a one-inch disk). Challenges associated with building miniature disk drives include electronics integration and packaging, design of miniaturized mechanical components, and extreme shock requirements.
Bringing Magnetic Levitation Trains to the USA: Technology and Policy Challenges (G)
Magnetic levitation trains (maglev), utilizing both attractive and repulsive magnetic forces for propulsion and guidance, are an attractive and energy efficient option for future rapid transportation. Electromagnetic attractive (in Germany) and superconducting repulsive (in Japan) maglev prototypes were successfully developed and demonstrated at speeds up to 500 Km/hr. In the US, the National Maglev Initiative (1990-95) laid the research foundation for a US maglev, but did not fund its development. Since 1998 the US Congress authorized DOT's Federal Rail Administration to manage a Maglev Deployment Program designed to bring maglev to the US for eventual high- speed intercity operation. In parallel, DOT's Federal Transit Administration Urban Maglev Research Program explores slower maglev options for urban and suburban transit applications. The status and prospects of leading technology options will be reviewed, touching on the safety, environmental, policy and socio-economic challenges to near term implementation of a US maglev.
Balancing Transportation, Energy and the Environment (G, P)
Maintaining a healthy, affordable and accessible transportation system is essential to our continued economic vitality and daily lives. Our vast transportation infrastructure network represents a 4 trillion dollars investment, including highways, roadways, bridges, waterways and ports, railroads, transit, airways and airports, as well as pipelines, passengers, freight and intermodal terminals. Increasing demand for transportation services, for both commercial cargo transport and for passengers travel, has taxed existing capacity and led to congestion and delays. The transportation sector consumes almost a third (28%) of our energy fuels, 3Ú4 of it by highway vehicles. Transportation represents almost 12% of the GDP and 10.5%, as well as contributing to environmental problems, from air pollution and greenhouse gases, to noise. Trends and projections in vehicles and modal energy consumption will be reviewed, as well as technology options, which promise to preserve our mobility, while improving energy efficiency and environmental quality.
Transportation in 2050: Technologies and Outlook (G, P)
In order to get to a future improved and renewed transportation system without a turbulent transition, we must first examine national and global trends to help envision a rational future and involve diverse stakeholders in a consensus-building exercise. It is essential to provide a roadmap to this future vision, including R&D program plans to fill knowledge gaps, development, test and evaluation of prototype systems to select viable technology options, and policies that incentivize innovations. I will share with you the transportation strategic planning and consensus-building process that I was part of, leading to Transportation Vision 2050 and its enabling technology building blocks, posted at http://scitech.dot.gov/polplan/vision2050/index.html
Electromagnetic Fields (EMF), Health and Environment Issues in Transportation (G, P)
For the past 30 years public concerns with potentially adverse health and environmental effects from electromagnetic fields (EMF) and radiation (EMR) have lingered in spite of weak and inconsistent scientific evidence. Voluminous multidisciplinary research, a Congressionally- mandated EMF Research and Public Information Dissemination (EMF-RAPID) 5 years program, NAS and NIEHS reports did not allay public fears and the debate continues. Numerous epidemiological and peer reviews concluded that evidence for an association of environmental EMF with childhood leukemia is weak. However, EMF and EMR sources are increasingly common and diverse our modern society and everyone is "exposed". Sources include home and office appliances, computers, security, communication and navigation devices as well as electric transportation and power transmission and distribution lines. My conclusions are based on my decade- long efforts to consistently measure, characterize and compare EMF and EMR from transportation sources with other common environmental exposures, participate in EMF interagency committees and working groups, and in the IEEE human exposure safety standards development.
Richard (Rit) Carbone
Got Weather? Swirls, Splashes and Waves in the Atmosphere (P)
Unlike the surface of water, air motions are often difficult to see with the naked eye. Animations of radar and satellite images and computer simulations reveal some amazing flows. How these flows relate to familiar clouds and storms helps to put human experiences in perspective.
When It Rains It Pours: A Tale of Two Islands (G)
Tropical islands are among the rainiest places on earth. Why is this so? Do all islands produce rainfall in a similar manner? These issues will be explored in a comparative study of Hawaii and the Tiwi Islands of Australia.
Will Thunderstorms Ever Be Predictable? (S)
There is not much skill associated with summertime rainfall prediction. Compared to other types of weather, thunderstorm forecasts are the worst, by far. Why is this? Why is it important to society? Can the science of meteorology and the technology of numerical weather prediction do something about it soon?
Charles H. Dowding
Carving Crazy Horse: Art and Engineering of Blasting Massive Rock Monuments (P, G, S)
When completed, Crazy Horse Memorial, an equestrian figure being carved in the round, will be the largest mountain carving in the world. Millions of tons of rock have been removed to date. The project began in 1939 when Chief Henry Standing Bear wrote to Korczak Ziolkowski asking him to carve the 600 ft. high monument in the Black Hills of South Dakota. When Korczak died in 1982, his wife Ruth and their children made the commitment to carry on his Dream, and work on the mountain continues today. This lecture describes the process of creating the monument. Project management includes financing, scheduling and public relations. Artistic considerations include replication of the prototype, sequencing of operations and final details. Blast matters involve drilling, explosive loading and initiation sequence. Rock mechanics aspects include special equipment, reinforcement, final smoothing by heating, and monitoring vibration response. The presentation includes color slides and movies and can be tailored to suit the interests of the audience. More information about the project can be found at www.crazyhorse.org.
Watching Our Infrastructure: Autonomous Surveillance of Critical Facilities and the Internet (G, S)
Internet display and digital data acquisition have revolutionized the process of monitoring the condition of critical facilities. Development of low power consumption microprocessors and storage devices now allow on site data acquisition without human intervention. Land-line modems, cell phones, and satellite communication provide the means of transmitting data from any location on the planet. Finally, internet display allows acquired information to be reviewed from any location. The Northwestern Infrastructure Technology Institute has been installing systems involving all three components to monitor bridges and other critical facilities. This lecture will describe details of these installations, as well as data acquired, its internet display and interpretation. Examples of ITI installations and activity can be found at www.iti.northwestern.edu/acm or www.iti.northwestern.edu/tdr by pressing "operational sites" on the left side bar.
Douglas J. Durian
The Physics of Foams (G)
Foams consist of gas bubbles jammed tightly together in a small amount of liquid. As a form of matter, are they solid, liquid, or gas? In fact foams possess hallmark features of all three basic states, in ways that are just now being understood. This talk will give an overview of the fascinating behavior of foams and a glimpse into current research topics considered by physicists and mathematicians.
Turning up the Heat on Effective Temperatures (S)
If left alone, materials like foam and sand are jammed -- the bubbles and grains are tightly locked into some static packing configuration and the material acts like a solid. If subjected to large forces, the packing units can unjam and the material acts like a liquid. Unlike a real liquid, though, the random grain dynamics are not controlled by thermal energy. What sort of statistics should the microscopic motions possess? In principle statistical mechanics does not apply. Surprisingly, in certain cases, it appears to hold but with a well-defined "effective temperature" that is much greater than the thermal temperature.
The Glamorous World of the Forensic Anthropologist: The True Story (P)
Television shows such as the New Detectives, Medical Detectives, CSI and even the X-Files have introduced many people to the work of forensic anthropologists. Consequently practicing professionals spend considerable time fielding questions from those who wish to make it their career. This presentation discusses a) what we do when not on television, b) what are the legal and health risks involved, and c) are there jobs in this field.
Forensic Analysis of Skeletal Trauma (G)
Bone has biomechanical properties that allow it to resist compressive and tensile forces, although to differing extents. Fracture is produced when the strength of the bone is surpassed. How the bone breaks allows forensic anthropologists to track back to the forces that produced the breaks and match them with known injury characteristics. Focusing on blunt force trauma and gunshot injuries, this presentation discusses the possibilities and limitations of skeletal analysis within the forensic context. Photographs of bone injuries and some soft tissue trauma are included.
The Legal Responsibilities of Forensic Anthropologists (S)
The skills of the skeletal biologist are the foundation upon which forensic anthropologists have built careers. How does forensic anthropology analysis differ from conducted in other contexts? What should anyone know before agreeing to take on a forensic case? What are the risks and responsibilities and how are the limitations of the field handled? May include images of decomposing bodies and soft tissue trauma.
Computing Metaphors and "E-Culture" (G)
Computational metaphors -- computer systems whose functionality intentionally mimics familiar human objects and entities -- are the foundation for many powerful computer systems. We are exploring some examples of this idea in the sciences and engineering areas. In particular, we are we are investigating different computer interfaces, whereby we look into the issue of creating information systems that reflect and support specific cultures. In this talk, I will highlight some of the issues raised by the work of the new Institute for African-American ECulture (http://www.iaaec.org).
Grid Power to the People (G)
Access to high quality distributed computing, information, and experimental resources are transforming science and the scientific community. This talk reviews the impact of distributed computing on selected scientific disciplines and projects and points to some key issues for future development.
Micromagnetic Simulations: Dynamics and Topology (S)
We review large-scale computer simulation of the Landau-Lifshitz equations which model the dynamics of magnetic materials in 3D. Of special interest is the representation of topological features of the model in discrete computer simulations.
The Subversiveness of Asking "Why?": Social Implications of Neuro-determinism (P)
It is common to wonder why people behave as they do. Less common is consideration of the implications of even supposing that the question might be answerable. This seminar considers causal accounts of human actions, and consequences for notions of responsibility and punishment. We find that while some traditional ideas are undermined, others are clarified and provide sufficient leeway for individual motivation and communal defense.
Crowding Induced Order: From Liquid Crystals to Cell Biology (G)
Solution non-ideality is more commonly regarded as an unpleasant fact of life than as a source of interesting phenomenology. Usually represented by simple activity coefficients overlaid on ideal descriptions, non-ideality is generally seen as quantitatively important but qualitatively insignificant. This seminar will take the opposite point of view, focusing on novel structural features and physical properties that arise from simple steric interactions between solutes in systems ranging from simple binary solutions to complex biological solutions. In the latter, the bundling of cytoskeletal proteins is shown to be driven simply by their excluded volume and the roles of cross-linking and capping proteins are necessarily reassessed.
Sensors and Pumps: Molecular Mechanisms of Retinal-Based Signal and Energy Transducers (G)
Halophilic archae produce retinal-containing membrane proteins similar to the mammalian visual pigments. These rhodopsins include energy transducers that use light to drive ion transport, as well as signal transducers that use light to stimulate phototaxis. The rhodopsins are thus light-driven analogues of the chemically-driven energy transducers (e.g., membrane ATPases) and signal transducers (e.g., hormone receptors) found in mammalian cells. In this talk we will consider how the requirements for effective sensors and pumps differ and how retinal is well suited to serve as a chromophore in both types of systems.
Pumping Ions: NMR Studies of Solar Energy Transduction in the Bacteriorhodopsin Photocycle (S)
Bacteriorhodopsin is a relatively stable membrane protein that functions as a light-driven ion pump. Interest has focused on the "gating" mechanism whereby ion release and uptake occur on opposite sides of the active site in the L-to-M and M-to-N transitions of the bacteriorhodopsin photocycle. Solid-state NMR spectra of the L, M and N photocycle intermediates have been obtained by trapping at low temperatures. Features of the spectra of these intermediates indicate that (1) "gating" is associated with the release of torsion in the chromophore and (2) the pump may be pumping hydroxyl ions into the cell rather than protons out of the cell.
Hydrogel Opals (G, S)
Our group has recently developed a new class of nanostructured hydrogels. The central idea to first synthesize monodispersed hydrogel nanoparticles, then self-assemble them into a 3D network, and eventually covalently bond them. The covalent bonding contributes to the structural stability, while self-assembly provides crystal structures that diffract light, resulting in a striking iridescence like opal. The work reviewed in this talk will include synthesizing mono-dispersed N-isopropylacrylamide nanoparticles with functional groups attached, characterizing self-assembling processes, describing the crosslinking chemistry, modeling elastic and optical properties associated with the nano-structures, and applying such nano-structured hydrogels for controlled drug release. The new material allows us to obtain useful functionalities not only from the constituent building blocks, such as their abilities to simulate biological tissues and to swell or collapse reversibly in response to external stimuli, but also from the long-range ordering that characterizes these structures.
Smart Hydrogels (P)
Hydrogels are a unique class of macromolecular networks and are particularly useful in biomedical and pharmaceutical applications mainly due to their high water content, which is similar to natural tissue, as well as their bio-compatibility. This talk will review some recent progresses on the smart hydrogels that may be induced to swell or shrink (taking up or expelling water between the crosslinked polymer chains) in response to a variety of environmental stimuli. These stimuli include changes in pH or temperature, or the presence of a specific chemical substance. A host of researchers are now rushing to explore the applications of these smart materials, aiming for everything from biosensors to drug release devices. And since gels can exert a force when they swell, they even have potential as actuators or artificial muscles for robots or prostheses. Hydrogels get smatter as their structures are engineered by incorporating several different gels. For example, a shape memory gel that consists of a responsive polymer network and a non-responsive network can change its shapes at various temperatures. Furthermore, a nanostructured hydrogel will be described, which displays a striking iridescence like precious opal but is soft and flexible like Jell-O.
Sea Level Rise and Ancient Maya Civilization (P, G )
What impact did environmental change have in the Classic Maya collapse around A.D. 900 in the tropical lowlands of Guatemala and Belize? Drought, increased rainfall, earthquake, and soil erosion have been suggested as agents in the collapse. Cataclysmic events such as the Ilopango volcanic eruption in the 5th century and Hurricane Iris in the 21st century destroyed Maya communities at other times. However, the impact of environmental change was neither uniformly felt across the Maya lowlands nor necessarily in sync with cultural changes at the end of the Classic. A model of the complex interplay between environmental change (sea-level rise) and cultural change in the Port Honduras of southern Belize is presented. Ongoing fieldwork documents a meter rise in sea level in the area that has inundated Classic Maya sites. The presentation will show the discovery and excavation of inundated sites and the evidence supporting late Holocene sea-level rise and the relationship between sea-level rise and archaeological sites in the region. Some, like the salt works in the Punta Ycacos Lagoon, were submerged and hidden from modern view. Others were inundated and are now buried under mangrove peat and living mangroves. Some, like Wild Cane Cay, continued to be occupied by the Postclassic Maya, possible in part due to the accumulation of centuries of ancient Maya trash. I evaluate the factors that led to the abandonment and continued occupation of Maya sites under the stress of sea-level rise. I argue that the abandonment of coastal salt works resulted not from their inundation by sea-level rise but from the lack of inland consumers.
Salt: White Gold of the Ancient Maya (G, P)
Salt, basic to daily human life, was scarce in the tropical rainforests of Belize and Guatemala where the Classic Maya civilization developed between A.D. 300 and 900. The prevailing interpretation is that vast quantities of salt were transported in boats from the salt flats along the north coast of Mexico's Yucatan peninsula. The discovery and excavation of shallow underwater salt works in Punta Ycacos Lagoon, in the Port Honduras of southern Belize, demonstrate there was a closer source of salt for the Classic Maya. Salt cakes were produced by boiling brine in pots over fires at the Punta Ycacos salt works. The standardized manufacture of the pots and other measures indicate specialized production of salt in workshops. The specialized production and the location of the workshops away from domestic settings and any major Maya city indicates the Maya engaged in independent craft production that was not under the direct control of the urban Maya. I will discuss the discovery, excavation, and analysis of the ancient salt works and their implications for our understanding of the ancient Maya economy and politics. Some mention will also be made of sea-level rise, which has inundated the salt works. They were on dry land at the time of their Late Classic use. This presentation can be geared to a general or public audience.
Ancient Maya Sea Traders (S)
Since Christopher Columbus' alleged encounter with a Maya trading canoe off the north coast of Honduras during his fourth voyage to the New World, scholars have debated the antiquity and importance of sea trade in the rise and fall of ancient Maya civilization. This presentation will summarize my studies of Maya sea trade, focusing on the analysis of obsidian-a volcanic glass not naturally occurring in the limestone platform of Mexico's Yucatan peninsula, Belize, and Guatemala where the Classic Maya civilization developed between A.D. 300 and 900. Quantities of obsidian were imported to make sharp cutting tools for a variety of tasks, including ritual bloodletting. The ability to chemically fingerprint the source locations of the obsidian trade goods assists in the reconstruction of ancient transportation and trade routes. I present the results of my fieldwork, including the excavation of sites in the search for obsidian and other trade goods at the Maya trading ports of Moho Cay and Wild Cane Cay in Belize, as well as regional survey in the Port Honduras of southern Belize. A variety of analyses on obsidian from these sites are presented to argue that Maya sea trade had a long and significant importance in the development of Maya civilization and in the subsequent Postclassic period. The analyses include chemical and visual identification of the sources of obsidian artifacts (XRF and NAA) as well as measures of the conservation of the raw material in the manufacture of blades (CE/M or "cutting edge to mass" index) and the relative abundance of obsidian artifacts (obsidian densities).
Isiah M. Warner
Mentoring: A Novel Method for Battering Brick Walls (P)
Mentoring has proven to be a powerful tool for guiding students through obstacles (symbolic brick walls) which stand in their way for success. Professor Warner has been a long time proponent of mentoring and has won numerous awards for his activities in this area. In this talk, Professor Warner will highlight his mentoring experiences with select students throughout his career. This talk will also highlight the success story regarding graduate education for African Americans at Louisiana State University (LSU), where a record number of African American students are pursuing and receiving PhDs in chemistry. It is noted that LSU has started to produce African Americans with Chemistry PhDs in numbers which are a significant fraction of the national output as a whole (8 out of 44 for 2001). Data from this program will be highlighted and possible keys to success (e.g. mentoring) will be discussed in this talk.
Chiral Drugs: The Jekyl/Hyde Behavior of These Molecules in Biological Systems (G)
Chiral drugs are molecules that are non-superimposable on their mirror images. Many active pharmaceutical drugs are chiral and are marketed as racemic mixtures, i.e. as an equal mole ratio of their individual enantiomers. The problem is that one enantiomeric form of a chiral drug may be medicinally beneficial while the other enantiomeric form may be completely useless or even toxic. An example of the latter is the drug, thalidomide, which was administered to pregnant women to combat "morning sickness" in the 1960's. It was later determined that one enantiomeric form of thalidomide was medicinally beneficial (minimized morning sickness), while the other enantiomeric form was found to be teratogenic. The result was babies born with severe limb deformities. Since this time, the FDA has required detailed studies of chiral drugs. This talk will highlight the many examples of this Jekyll/Hyde behavior among chiral drugs. Some examples of reagents and methods that we have developed for separation of these molecules will also be discussed.
Mixing Chromatography and Spectroscopy to Achieve Chiral Recognition With Molecular Micelles (S)
Capillary Electrophoresis (CE) has become an important analytical tool for separation of charged analytes. This is because of the enhanced separation efficiency of the CE method for charged analytes. In addition, the CE method when used in combination with a micellar pseudostationary phase offers a number of advantages for separation of neutral analytes. This latter approach is called micellar electrokinetic chromatography (MEKC) and has been evolving with the use of other pseudostationary phases for the last two decades. In our laboratory, we have recently employed chiral polymeric surfactants (molecular micelles) for enhanced enantiomeric separations of racemic mixtures using MEKC. Our studies have shown that these polymers are usually more suitable than conventional micelles in MEKC. We have also sought to understand the factors which contribute to effective enantiomeric separation by use of chiral polymeric surfactants and in that regard, to develop better reagents. One of the methods that we have explored for probing chiral recognition, with great success, is fluorescence anisotropy (FA)(JACS 2001, 123, 3173-3174). We have demonstrated that FA directly correlates with our chromatographic measurements and that it is possible to extract the difference in free energy of interaction between two enantiomers by use of FA measurements. This talk will highlight some of our recent studies in the development of our chiral reagents and the use of FA to probe chiral recognition.