We present observations of narrowband subionospheric VLF transmitter signals on 20 March 2001, exhibiting coherent fluctuations of over 1 dB peak to peak. Spectral analysis shows that the fluctuations have periods of 1–4min and are largely coherent. The subionospheric propagation path of the signal from Puerto Rico to Colorado passes over two regions of convective and lightning activity, as obs...

[1] It is shown theoretically that for high power HF ionospheric heaters, such as the current HAARP heater, the HF to VLF conversion can increase significantly by using a two-timescale heating. A long heating pulse, tp 1minute, is followed over the same timescale period bymodulation at the desired ELF/VLF frequency. The long pulse reduces the electron-ion recombination coefficient, resulting in...

In this paper, the amplitude probability density (APD) of the wideband extremely low frequency (ELF) and very low frequency (VLF) atmospheric noise is studied. The electromagnetic signals from the atmosphere, referred to herein as atmospheric noise, was recorded by a mobile low-temperature superconducting quantum interference device (SQUID) receiver under magnetically unshielded conditions. In ...

Scaling analysis of heart rate time series has emerged as a useful tool for the assessment of autonomic cardiac control. We investigate the heart rate time series of ten athletes (five males and five females), by applying detrended fluctuation analysis (DFA). High resolution ECGs are recorded under standardized resting conditions over 30 min and subsequently heart rate time series are extracted...

Lightning is located by using the time of group arrival (TOGA) of the VLF (3–30 kHz) radiation from a lightning stroke. The dispersed waveform (“sferic”) of the lightning impulse is processed at each receiving site. The TOGA is determined relative to GPS at each site from the progression of phase versus frequency using the whole wave train. Unlike current VLF methods which require transmission ...

The variations of phase and amplitude of a subionospheric transmitted signal at frequency 19.8 kHz from North West Cape, Australia (latitude: 21.82◦S; longitude: 114.16◦E) measured at Kolkata (latitude: 22.56◦N, longitude: 88.5◦E) during the period of solar eclipse (partial, 91.1%) on July 22, 2009 will be presented in this paper. The variations in amplitude are quite significant than the usual...

two dimensional single frequency scalar vlf data modeling has been studied in this research. vlf method is one of the electromagnetic investigation methods. radio frequency waves are used for investigation of conductive deposits (paal, 1968). synthetic modeling and inversion of single frequency and multiple frequencies of vlf signals was done by oskooi (2004) for two dimensional simple structur...

Mitsis, Georgios D., Rong Zhang, Benjamin D. Levine, and Vasilis Z. Marmarelis. Cerebral hemodynamics during orthostatic stress assessed by nonlinear modeling. J Appl Physiol 101: 354–366, 2006. First published March 2, 2006; doi:10.1152/japplphysiol.00548.2005.—The effects of orthostatic stress, induced by lower body negative pressure (LBNP), on cerebral hemodynamics were examined in a nonline...

The effects of orthostatic stress, induced by lower body negative pressure (LBNP), on cerebral hemodynamics were examined in a nonlinear context. Spontaneous fluctuations of beat-to-beat mean arterial blood pressure (MABP) in the finger, mean cerebral blood flow velocity (MCBFV) in the middle cerebral artery, as well as breath-by-breath end-tidal CO2 concentration (P(ET(CO2))) were measured con...