Philippe A. Robert

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A new method of physical activity monitoring is presented, which is able to detect body postures (sitting, standing, and lying) and periods of walking in elderly persons using only one kinematic sensor attached to the chest. The wavelet transform, in conjunction with a simple kinematics model, was used to detect different postural transitions (PTs) and(More)
A new method of evaluating the characteristics of postural transition (PT) and their correlation with falling risk in elderly people is described. The time of sit-to-stand and stand-to-sit transitions and their duration were measured using a miniature gyroscope attached to the chest and a portable recorder placed on the waist. Based on a simple model and(More)
A novel method for Brillouin gain spectrum measurements in optical fibers is presented. It is based on the pump and probe technique with the specificity to use a single laser source together with an external modulator to generate the interacting lightwaves. The high accuracy and inherent stability of the technique makes it suitable for calibration and(More)
A novel configuration of a distributed fiber sensor by Brillouin gain analysis has been developed for temperature and strain monitoring. It uses a single laser source, and the required light signals are all generated with an electro-optic modulator, resulting in high stability and excellent reliability of the measuring setup. Measurement of the induced(More)
A theoretical model of wavelength modulation spectroscopy that uses a laser diode on a Lorentzian absorption line is presented. This theory describes the general case of a current-modulated semiconductor laser, for which a combined intensity and frequency modulation with an arbitrary phase shift occurs. On the basis of this model, the effect of several(More)
A retrospective survey on drug prescription over a one-year period (1989) in 1083 patients (48.3% of whom were male) hospitalized in a psychiatric university hospital in Switzerland and a 35-day prospective study (1992) on the prescription of "as needed" (prn) medication in a closed and an open ward were carried out. Their aim was to establish a basis for a(More)
A novel method for characterization of optical fiber resonators by an optical time-domain reflectometry (OTDR) technique is reported. This easy-to-use technique yields accurate results for cavity lengths ranging from a few meters to several kilometers. A simple relationship is established between the round-trip cavity loss and the position where the OTDR(More)
T cell activation requires that the cell meet increased energetic and biosynthetic demands. We showed that exogenous nutrient availability regulated the differentiation of naïve CD4(+) T cells into distinct subsets. Activation of naïve CD4(+) T cells under conditions of glutamine deprivation resulted in their differentiation into Foxp3(+) (forkhead box(More)
Stimulated Brillouin Scattering (SBS) shows the lowest threshold among all non-linear processes observed in optical fibers . It is also strongly dependent on local physical parameters of the fiber, since the scattered light experiences a frequency downshift v@h respect to the incident light proportional to the acoustic velocity within the fiber, this latter(More)