Overcoming the Impedance Range Limitations of Portable Bioelectrical Impedance Spectroscopy Clinical Devices.

Several portable commercial bioimpedance spectroscopy (BIS) devices are used in clinical research, but are limited by their reduced impedance measuring range to less demanding four-electrode configuration measurements. Some of these devices provide raw bioimpedance data for research purposes. The SFB7 device from ImpediMed® is a typical portable clinical device which perform 256 measurement points from 3 kHz to 1 MHz, providing for each point the resistance R and the reactance X.

Nesting chinstrap penguins accrue large quantities of sleep through seconds-long microsleeps.

Microsleeps, the seconds-long interruptions of wakefulness by eye closure and sleep-related brain activity, are dangerous when driving and might be too short to provide the restorative functions of sleep. If microsleeps do fulfill sleep functions, then animals faced with a continuous need for vigilance might resort to this sleep strategy. We investigated electroencephalographically defined sleep in wild chinstrap penguins, at sea and while nesting in Antarctica, constantly exposed to an egg predator and aggression from other penguins.

Pulse wave velocity measurement along the ulnar artery in the wrist region using a high frequency ultrasonic array.

A pulse wave velocity (PWV) measurement method performed above a small blood vessel using an ultrasonic probe is studied and reported in this paper. These experimentations are carried out using a high-frequency probe (14-22 MHz), allowing a high level of resolution compatible with the vessel dimensions, combined with an open research ultrasound scanner. High frame-rate (HFR) imaging (10 000 frames per second) is used for a precise PWV estimation.

Pupillary behavior during wakefulness, non-REM sleep, and REM sleep in birds is opposite that of mammals.

Mammalian pupils respond to light and dilate with arousal, attention, cognitive workload, and emotions, thus reflecting the state of the brain. Pupil size also varies during sleep, constricting during deep non-REM sleep and dilating slightly during REM sleep. Anecdotal reports suggest that, unlike mammals, birds constrict their pupils during aroused states, such as courtship and aggression, raising the possibility that pupillary behavior also differs between mammals and birds during sleep.

Optical flow sensor as a reference for reduction of motion artefacts in photoplethysmographic measurements.

Methods commonly used for reduction of motion artefacts in photoplethysmography employ accelerometry as a reference for adaptive filtering and signal processing. In this paper, we propose the use of an optical flow sensor to measure the relative displacement between a photoplethysmographic sensor and the measurement site. In order to evaluate the performances of this novel method, a wrist-worn device that enables simultaneous acquisition of physiological information and relative motion has been developed.