James Wanliss

Does exposure to an artificial ULF magnetic field affect blood pressure, heart rate variability and mood?

The aim of this study was to determine whether an artificial magnetic field with an amplitude and frequency equivalent to those of geomagnetic pulsations during geomagnetic storms could affect physiology and psychology. Three healthy volunteers wore anambulatory BP monitor and an ECG recorder around the clock for 12 consecutive weekends in Winnipeg, Manitoba, Canada. In a room shielded against ELF and VLF waves, they were exposed for 8 hours per week to either a 50 nT 0.0016 Hz or a sham magnetic field at one of six circadian stages. Real exposure randomly alternated with sham exposure. They provided saliva and recorded mood and reaction time every 4 hours while awake. Systolic (S) and diastolic (D) blood pressure (BP), and heart rate (HR) were recorded every 30 minutes. Spectral analysis of HR variability (HRV) was performed using the maximum entropy method and a complex demodulation method. For these variables, daily means were compared between real and sham exposure, using paired t-tests. Their circadian MESOR, amplitude, and acrophase were analyzed and summarized using single cosinor and population-mean cosinor. Circadian rhythms were demonstrated for HR, SBP, DBP for sham exposure, salivary flow rate, positive affect, vigor, and subjective alertness (p < 0.001, -0.02). One participant showed higher HR, lower LF, HF, and VLF powers, and a steeper power-law slope (p < 0.005, -0.0001) in an early night exposure to the real magnetic field, but not in other circadian stages. There was no significant difference between circadian responses to real and sham exposure in any variable at any circadian stage.

Initial studies of high latitude magnetic field data during different magnetospheric conditions

We investigate the statistical properties of high-latitude magnetometer data for differing geomagnetic activity. This is achieved by characterizing changes in the nonlinear statistics of the geomagnetic field, by means of the Hurst exponent, measured from a single ground-based magnetometer station. The long-range statistical nature of the geomagnetic field at a local observation site can be described as a multifractional Brownian motion, thus suggesting the statistical structure required of mathematical models of magnetospheric activity. We also find that, in general, the average Hurst exponent for quiet magnetospheric intervals is smaller than that for more active intervals.

Auroral substorm dynamics and field line resonances

Magnetospheric substorms frequently have oscillating auroral phenomena associated with them, and which may be related to field line resonances. In this paper we present an analysis of photometer data which displays such oscillations in luminosity. We use data from the Gillam station in the CANOPUS array for April 1, 2000. Clear pulsations in magnetometer and photometer data are observed at 2.2 mHz. The latitudinal distribution of the photometer pulsations indicates that the auroral luminosity variations, caused by precipitating electrons and protons, are modulated by large scale global compressional modes (field line resonances). The proton and electron auroras were found to oscillate essentially out of phase. As well, the variation of phase across the peak in the luminosity resonance follows the pattern expected for the coupling of resonant Alfve’n modes by normal compressional modes in the magnetotail.

Frequency‐doubled density perturbations driven by ULF pulsations

We present Active Magnetospheric Particle Tracer Explorers Ion Release Module (AMPTE IRM) observations of a wave packet of compressional Pc5 ULF oscillations between 0915 and 1030 UT on October 28, 1984. The waves are observed in the local morning near the equatorial plane, have a dominant period of ∼ 380 s, and most probably have a fundamental field-aligned harmonic structure. The waves have previously been interpreted as a magnetospheric waveguide mode propagating downtail [Mann et al., 1998]. At the time of the maximum amplitude of the waves, AMPTE IRM observes oscillations in the background density at a frequency twice that of the coincident ULF pulsations. We develop a theory which explains the generation of frequency-doubled density fluctuations through large-amplitude radial displacements of curved flux tubes in a nonadiabatic background plasma pressure distribution. The theory predicts a phase locking between the peaks and troughs of the radial velocity field and the peaks in the frequency-doubled density oscillations which is observed by AMPTE IRM. The observations strongly support the hypothesis that the frequency doubling occurs as a result of finite amplitude effects.

Fractal modeling of human psychomotor skills acquisition process

Existing research on human skills acquisition studies has shown that learning follows a non-linear pattern, but the exact form remains unknown due to the limitation of traditional experimental methods and lack of systematic modeling of tasks. We applied a non-linear fractal analysis on the time series data produced by human subjects on target-tracking motor learning tasks. Tracking of a non-fractal sinusoid-cosinusoid signal was used as the platform. Our preliminary results suggest that fractal models may prove effective in investigating details of the human learning process.