professional experiences and research interests range from mechanical engineering facilities design to research that applied engineering and molecular biology approaches to the study of the skeletal response to mechanical loading. As a Mechanical Engineer, she worked on facility design projects involving mechanical systems that included heating, ventilation, air conditioning, and energy conservation systems, as well as R&D of air conditioning equipment for Navy ships. Additional research interests include the investigation of relationships among components of the indoor environment, occupants, and energy usage. Specifically, the effects of the indoor environment on occupant health and well-being and in parallel, how socially-mediated energy-saving strategies can increase awareness of energy use and/or increase energy saving behaviors. of group development fits the macrocosmic evolution of the program and is used as a framework within which to place the experiences, observations, and perspectives of the individuals associated with its conception and direction. Examples are provided of processes, failures, successes, and lessons learned, and references are provided to quantitative works describing the results of Program assessment over time.

and is currently a doctoral candidate in the same program. The primary focus of her research concerns assessing the response structure of test scores using item response theory methodology.

Recent interest has developed within the environmental community in measuring the effective diffusion coefficient (De) of gases through soil. An electroacoustic system will be described that uses a plane-wave resonator and a phase-locked-loop automatic resonance frequency tracker. The gas analyzer is simple and can be built for about $100 from readily available plumbing parts and inexpensive transducers. A soil core is fitted into the top of a valved sample chamber and the resonator below is charged with a pure ‘‘tracer’’ gas (e.g., He, SF6), then the valve opened. The rate at which the tracer gas is replaced by air within the resonator is controlled by the soil’s De. The resonant frequency is maintained by a phase-locked-loop that compares the signal from an electret microphone with a square wave reference generated by the same monolithic function generator (XR 2206) that excited an electrodynamic loudspeaker with a sinusoidal current. The resonator temperature is monitored using a monolithic IC temperature sensor (AD 592) providing an output current of 1 μA/K. The mean molecular weight of the gas mixture in the resonator is directly determined in real-time from the ratio of the absolute temperature to the square of the fundamental acoustic resonance frequency. [Work supported by ONR.]

Diffusion of gases through porous media is commonly described using Fick’s law and is characterized by a gas diffusion coefficient modified by a media-specific tortuosity parameter. A phase-locked-loop resonance frequency tracker [J. Acoust. Soc. Am. 108, 2520 (2000)] has been upgraded with an insulated copper resonator and a bellows-sealed piston instrumented with an accelerometer. Average system stability (temperature divided by frequency squared) is about 180 ppm. Glass-bead-filled cores of different lengths are fitted into an o-ring sealed opening at the top of the resonator. The rate at which the tracer gas is replaced by air within the resonator is controlled by the core’s diffusion constant. Mean molecular weight of the gas mixture in the resonator is determined in real time from the ratio of the absolute temperature to the square of the fundamental acoustic resonance frequency. Molecular weight of the gas mixture is determined approximately six times per minute. Changes in the gas mixture concentration are exponential in time (within 0.1%) over nearly two decades in concentration. We will report diffusion constants for two different sizes of glass beads, in samples of five different lengths, using two different tracer gases, to establish the validity of this approach. [Work supported by ONR.]

is an Instructional Developer with the Bernard M. Gordon-MIT Engineering Leadership Program. Her current interests are project-based learning, simulations involving leadership scenarios, and the intersection of technology and education.