Biomedical subjects

Vincent Noel

Publications and source records attributed to Vincent Noel.

3 recordsLinked to original sources

PubMed2006

Simple relation between lidar multiple scattering and depolarization for water clouds.

An empirical relationship is derived between the multiple-scattering fraction and the linear depolarization ratio by using Monte Carlo simulations of water clouds measured by backscatter lidar. This relationship is shown to hold for clouds having a wide range of extinction coefficients, mean droplet sizes, and droplet size distribution widths. The relationship is also shown to persist for various instrument fields of view and for measurements made within broken cloud fields. The results obtained from the Monte Carlo simulations are verified by using multiple-field-of-view lidar measurements. For space-based lidars equipped to measure linear depolarization ratios, this new relationship can be used to accurately assess signal perturbations due to multiple scattering within nonprecipitating water clouds.

Journal Article↗

PubMed2006

Selectivity and sensitivity of a reagentless electrochemical DNA sensor studied by square wave voltammetry and fluorescence.

Poly(5-hydroxy-1,4-naphthoquinone-co-5-hydroxy-3-thioacetic acid-1,4-naphthoquinone)-modified electrode is used for the direct electrochemical detection of oligonucleotide hybridization. The polymer film presents well-defined electroactivity in the cathodic potential domain (between 0 and -0.8 V/SCE), due to the quinone group embedded into the polymer structure. The detection can be performed simply by square wave voltammetry. This sensor is a "signal-on" device and works with different oligonucleotide lengths, from 10 to 30 bases. Quantitative results from fluorescence are consistent with electrochemical data. It is confirmed that the signal increase in square wave voltammetry is unambiguously due to hybridization. The biosensor presents a detection limit of target of ca. 25 nM and is highly selective as it can discriminate single mismatch base.

Biosensing Techniques↗

PubMed2002

Classification of particle effective shape ratios in cirrus clouds based on the lidar depolarization ratio.

A shape classification technique for cirrus clouds that could be applied to future spaceborne lidars is presented. A ray-tracing code has been developed to simulate backscattered and depolarized lidar signals from cirrus clouds made of hexagonal-based crystals with various compositions and optical depth, taking into account multiple scattering. This code was used first to study the sensitivity of the linear depolarization rate to cloud optical and microphysical properties, then to classify particle shapes in cirrus clouds based on depolarization ratio measurements. As an example this technique has been applied to lidar measurements from 15 mid-latitude cirrus cloud cases taken in Palaiseau, France. Results show a majority of near-unity shape ratios as well as a strong correlation between shape ratios and temperature: The lowest temperatures lead to high shape ratios. The application of this technique to space-borne measurements would allow a large-scale classification of shape ratios in cirrus clouds, leading to better knowledge of the vertical variability of shapes, their dependence on temperature, and the formation processes of clouds.

Journal Article↗