"sweat ducts in human skin are helically shaped tubes, filled with a conductive aqueous solution ... This ... brings forward the supposition that as electromagnetic entities, the sweat ducts could be regarded as low Q helical antennas ... Thus, the skin spectral response in the sub-Terahertz region is governed by the level of activity of the perspiration system ... It is also correlated to physiological stress as manifested by the pulse rate and the systolic blood pressure. As such, it has the potential to become the underlying principle for remote sensing of the physiological parameters and the mental state of the examined subject."