Sigma Xi Distinguished Lecturers 2002-2003 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.
Aviva Brecher
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.
Gail Charnley
Protecting the Children: Risk Assessment, Risk Management, and Children's Environmental Health (G)
Studies show that as the 21st century begins, the health and safety of children in America are better than at any time in recorded history. Mortality rates for all children (from newborn to 19 years of age) have dropped over 90 percent since the turn of the last century, contributing 60 percent of the 27-year increase in life expectancy since 1900. Children's health has improved especially during the last 20 years, indicating that children in particular have benefited from advances in medicine and social policy. The extent to which exposures to occupational and environmental chemical exposures contribute to childhood mortality is unknown, but has been estimated to be 1 percent. By comparison, mortality for all age groups due to these same exposures is estimated at 3 percent. The extent to which chemical exposures contribute to childhood disease or hinder development is also not known. Consequently, increasing attention over the last 10 years has been given to the potentially disproportionate impact that environmental chemical exposures might have on the health of children. That concern has led to new research and regulatory initiatives intended to improve our understanding and our ability to protect children from potential environmental risks. Some of those initiatives remain controversial, however, due to scientific uncertainty. There is general agreement that infants and children experience environmental chemical exposures differently from adults. Less certain is the extent to which children are of greater or lesser susceptibility to chemical toxicity than adults. This presentation provides an overview of what is known about differences in exposure and about differences in susceptibility, discusses how those differences are addressed when health risks are assessed, and draws conclusions about children's environmental health in the larger context of public health.
Communicating About Environmental Health Risks: Using Science to Shape Policy (S or G?)
Risk communication has evolved significantly since a National Academy of Sciences committee characterized it as a means of articulating differences between scientific evidence and scientific inference for the benefit of scientists and regulatory risk managers. But while we have come a long way, significant challenges remain. Physical and biological scientists are still learning how to communicate with social scientists; scientists are still learning how to communicate with policy-makers, lawyers, and regulators; and the US is still learning how to communicate with the rest of the world. The biggest challenge for the future of risk communication is going to be maintaining a role for risk assessment and preserving the integrity of science when risk management is influenced by many nontechnical factors. This challenge becomes especially critical as risk management decision-making is conducted increasingly as collaborative efforts among stakeholders with differing technical knowledge levels, interests, goals, and world views. If nontechnical stakeholders do not understand the science or the role it can play in decision-making, it is unlikely to play a significant role. If the scientists or technically oriented stakeholders do not understand what the real concerns of the other stakeholders are, then science — no matter how well deployed — will not solve the problem. And because scientific knowledge is always uncertain and incomplete, social decisions about the nature, extent, and appropriate response to risks are likely to remain controversial. This presentation describes how environmental health risk management decision-making is becoming more democratic and includes recommendations for preserving a role for science.
Reducing Risks to Our Health and Our Environment: The Roles of Science and Precaution (G)
There are no magic equations to define precisely how much science is needed to serve as the basis for taking actions to reduce environmental threats. The US generally waits until a problem is well defined scientifically before protective actions are taken. That approach is consistent with the US legal tradition, but opponents justifiably point to the preventable health consequences of delaying regulatory action while scientific analysis is debated. A reaction to the US approach has been the rise in Europe of the so-called "precautionary principle." The precautionary principle is defined in a number of different ways and its interpretation appears to depend on one's policy goals. The short and sweet definition is: Better safe than sorry. That is, it is better to take actions to prevent a possible risk even if it has not been adequately characterized scientifically. In Europe and in most of the rest of the industrialized world, government regulatory decisions are not subject to judicial challenges in court to nearly the same degree as they are in the US and the necessary procedures for marshaling and analyzing scientific evidence before a decision is made are thus nowhere near as great. In such an atmosphere, precaution is more easily proposed as the basis for decision-making. This presentation will describe how science-based environmental health risk management decision-making has evolved in the US and how a policy of science-based precaution might work to improve public and environmental health protection.