Dosimetry considerations for electrical stun devices.

Electrical dosimetry issues are discussed in relation to electrical stun devices (ESDs). A measure of effectiveness is based on a 'threshold factor,' F(T), calculated with a myelinated nerve model that simulates stimulation of a reference-case neuron (20 microm diameter, 1 cm distant). Several ESDs were measured in the laboratory using resistive loads of 100-1000 Omega; some included air gaps bridged via an electric arc. Conducted current waveform parameters and the associated threshold factors depend on the resistance of the load. Thresholds were also determined for ideal monophasic and biphasic square-wave stimuli, and compared with measured ESD waveforms. Although F(T) is proposed as a metric of strength, an approximate surrogate is the charge within the largest phase of the current versus time waveform. The approximation is reasonably accurate for monophasic waveforms with phase durations below about 100 micros, and for charge-balanced biphasic square-wave stimuli with phase durations between about 40 and 100 micros.

Family-Based Behavioral Treatment for Childhood Obesity: Caretaker-Reported Barriers and Facilitators.

BACKGROUND: Family-based behavioral treatments are effective ways to promote children's weight management through healthy eating and exercise. However, programs typically have high attrition and low attendance. The aim of this study was to obtain in-depth caregiver input on barriers and facilitators to participate in a family-based, behavioral childhood obesity treatment program. METHODS: Three focus groups were facilitated among 21 parents/guardians at 2 school-based health centers and 1 federally qualified health center. Audio recordings were transcribed and uploaded into NVivo software to assist in thematic coding. RESULTS: Focus group participants were females aged 18-57 years, of whom 71% were black, and 81% were not married. Participants listed numerous barriers: lack of time, frustration from prior unsuccessful weight-loss attempts, and the perceived cost of healthy foods and exercise options. Facilitators included a convenient location, a supportive weight-loss program leader, and rewards for the child's progress. CONCLUSION: Future interventions should incorporate caregivers' perspectives to develop sustainable, feasible strategies for the treatment of childhood obesity.

Comments on "Evaluation of interactions of electric fields due to electrostatic discharge with human tissue".

Attention is drawn to recent paper by Rogers et al. (Aug., 2004) in which ultra-wideband pulses are applied to an isolated muscle as part of deriving a strength-duration curve for threshold stimulation. The paper extends the strength-duration threshold curve for unipolar pulses down to a pulse duration of about 1 ns, on the order of 1000 times shorter than previously studied. Results of the work justify use of traditional mathematical models of the strength-duration curve for nanosecond pulses, as done recently for the electric field resulting from electrostatic discharge through the body (Dawson, et al., 2004).

40-Hz square-wave stimulation requires less energy to produce muscle contraction: compared with the TASER® X26 conducted energy weapon.

Conducted energy weapons (CEWs) (including the Advanced TASER(®) X26 model produced by TASER International, Inc.) incapacitate individuals by causing muscle contractions. In this study using anesthetized swine, the potential incapacitating effect of primarily monophasic, 19-Hz voltage imposed by the commercial CEW was compared with the effect of voltages imposed by a laboratory device that created 40-Hz square waves. Forces of muscle contraction were measured with the use of strain gauges. Stimulation with 40-Hz square waves required less pulse energy than stimulation with the commercial CEW to produce similar muscle contraction. The square-pulse stimulation, at the higher repetition rate, caused a more complete tetanus at a lower energy. Use of such a simple shape of waveform may be used to make future nonlethal weapon devices more efficient.

Muscle contraction during electro-muscular incapacitation: A comparison between square-wave pulses and the TASER(®) X26 Electronic control device.

Electronic control devices (including the Advanced TASER(®) X26 model produced by TASER International) incapacitate individuals by causing muscle contractions. To provide information relevant to development of future potential devices, effects of monophasic square waves with different parameters were compared with those of the X26 electronic control device, using two animal models (frogs and swine). Pulse power, electrical pulse charge, pulse duration, and pulse repetition frequency affected muscle contraction. There was no difference in the charge required, between the square waveform and the X26 waveform, to cause approximately the same muscle-contraction response (in terms of the strength-duration curve). Thus, on the basis of these initial studies, the detailed shape of a waveform may not be important in terms of generating electro-muscular incapacitation. More detailed studies, however, may be required to thoroughly test all potential waveforms to be considered for future use in ECDs.