Gas concentration measurement by optical similitude absorption spectroscopy: methodology and experimental demonstration.

We propose a new methodology to measure gas concentration by light-absorption spectroscopy when the light source spectrum is larger than the spectral width of one or several molecular gas absorption lines. We named it optical similitude absorption spectroscopy (OSAS), as the gas concentration is derived from a similitude between the light source and the target gas spectra. The main OSAS-novelty lies in the development of a robust inversion methodology, based on the Newton-Raphson algorithm, which allows retrieving the target gas concentration from spectrally-integrated differential light-absorption measurements.

Two-channel snapshot Mueller matrix polarimeter.

We describe a new setup for a snapshot Mueller matrix polarimeter (SMMP). It relies on the separation and orthogonal polarization of two light beams by a Wollaston prism located at the setup output. The simultaneous treatment of the two spectra allows an enhancement of accuracy for real-time measurements through reduction of the effects caused by random noise and systematic errors.

ACTH-independent Cushing's syndrome with bilateral micronodular adrenal hyperplasia and ectopic adrenocortical adenoma.

Context: Bilateral micronodular adrenal hyperplasia and ectopic adrenocortical adenoma are two rare causes of ACTH-independent Cushing's syndrome.

Objective: The aim of the study was to evaluate a 35-yr-old woman with ACTH-independent hypercortisolism associated with both micronodular adrenal hyperplasia and ectopic pararenal adrenocortical adenoma.

Design And Setting: In vivo and in vitro studies were performed in a University Hospital Department and academic research laboratories.