Tom Roberts

Asymptotics and energy estimates for electromagnetic pulses in dispersive media

We examine electromagnetic pulse propagation in anomalously dispersive media, using the Debye model as an example. Short-pulse, long-pulse, short-time, and long-time approximations and amplitude rate-of-decay estimates are derived with asymptotic methods. We also study the following problem: If we know only the peak amplitude and the energy density of an incident pulse, what can be said about the amplitude of the propagated pulse? We provide tight upper and lower bounds for the propagated amplitude, which may be useful in controlling the electromagnetic interference or the damage produced in dispersive media. We explain a factor-of-nine effect in the speed of pulses in a Debye model for water, which seems to have been previously unnoticed, and we also explain some observations from experimental studies of pulse propagation in biological materials. Finally, we propose some guidelines for sample size in transmission time-domain spectroscopy studies of dielectrics. Most of our results are easily extended to multiple space dimensions.

Fitness Guidelines for Rock Climbing Students

Abstract Rock climbing is a vigorous activity that requires a unique combination of strength and power balanced with endurance and flexibility. In the mind of a dedicated rock climber, developing and maintaining an adequate level of fitness is as important as the technical aspects of the sport.

How to Incorporate Self-Defense Instruction into Physical Activity Programs.

in the United States in 2010, which included 3,148,250 assaults and 188,380 rapes or sexual attacks. This equates to more than 9,000 assaults per day nationwide (U.S. Department of Justice, 2011). These numbers alone are prime examples of why self-defense is in demand in some form or fashion by all demographics of society. By Christopher S. Ousley, Ritchie G. Shuford, and Tom Roberts How to Incorporate

Learn More in Less Time: Fundamental Aquatic Skill Acquisition via Video Technology

STRATEGIES 29 Here’s a question (or two) about your aquatics program: Should aquatic instructors/coaches use video technology? Are the costs and time worth the effort? All signs point to yes and this article will show why aquatic instructors should take advantage of video technological advances and use them as an aid in the classroom. Recent advances in the technology fi eld have changed the way video support should be considered. It is now much more user-friendly and feasible than it was as recently as 10 years ago. In part because of these signifi cant strides, current literature supports the use of video technology in the classroom. This article focuses on the innovative use of video technology for specifi c aquatic motor skills used in our university’s intermediate swim classes, although this technology can also be used for numerous aquatic activities (e.g., SCUBA classes, diving classes, lifeguard training, team practices, etc.). The incorporation of digital cameras, underwater cam-sticks, video editing software, TiVo® feedback, and an on-line video questioning tool will allow aquatic students to learn more in less time. This article will add a new dimension to aquatics instruction literature because of the descriptions, explanations, and video links to video technology teaching tools. Literature Supports Video Technology’s Use