Phase sensitive sensor on plasmonic nanograting structures.

In this paper, a concept of phase sensitive sensor based on plasmonic nanograting structures with normal incidence and transmission detection is presented. Performed theoretical modeling enables fabrication of nanostructures with optimal geometry for polarimetric measurements of the phase difference between s- and p- polarized light. High phase resolution of the optical setup (6*10(-3) deg.) allows detection of the bulk refractive index with sensitivity equal to 3.8*10(-6) RIU. Proposed technique presents a more efficient alternative to the conventional spectral interrogation method of nanoplasmonic-based sensing and could be used for multisensing or imaging applications.

Designing efficient zero calibration point for phase-sensitive surface plasmon resonance biosensing.

This work is related to the development of phase-sensitive methodologies in Surface Plasmon Resonance (SPR) biosensing. We take advantage of a specific angular dependence of phase of light, reflected under SPR geometry, on parameters of the SPR-supporting metal, and propose a polarimetry-based methodology to easily determine the optimal calibration zero point, corresponding to the maximal phase sensitivity. The proposed methodology can significantly facilitate the calibration of the system in field and multi-channel sensing, broaden the dynamic range, as well as contribute to the development of feedback loops.

Mechanical modulation method for ultrasensitive phase measurements in photonics biosensing.

A novel polarimetry methodology for phase-sensitive measurements in single reflection geometry is proposed for applications in optical transduction-based biological sensing. The methodology uses altering step-like chopper-based mechanical phase modulation for orthogonal s- and p- polarizations of light reflected from the sensing interface and the extraction of phase information at different harmonics of the modulation. We show that even under a relatively simple experimental arrangement, the methodology provides the resolution of phase measurements as low as 0.007 deg. We also examine the proposed approach using Total Internal Reflection (TIR) and Surface Plasmon Resonance (SPR) geometries. For TIR geometry, the response appears to be strongly dependent on the prism material with the best values for high refractive index Si. The detection limit for Si-based TIR is estimated as 10(-5) in terms Refractive Index Units (RIU) change. SPR geometry offers much stronger phase response due to a much sharper phase characteristics. With the detection limit of 3.2*10(-7) RIU, the proposed methodology provides one of best sensitivities for phase-sensitive SPR devices. Advantages of the proposed method include high sensitivity, simplicity of experimental setup and noise immunity as a result of a high stability modulation.

Measles vaccine effectiveness in standard and early immunization strategies, Niger, 1995.

BACKGROUND: An Expanded Programme on Immunization was started in late 1987 in Niger, including vaccination against measles with one dose of standard titer Schwarz vaccine given to infants after 9 months of age. During epidemics an early two-dose strategy was implemented (one dose between 6 and 8 months and one dose after 9 months). From January 1, 1995, until May 7, 1995, 13 892 measles cases were reported in Niamey, Niger. METHODS: A retrospective cohort study was conducted in a crowded area of Niamey at the end of the outbreak to assess the effectiveness of measles vaccine in standard (after 9 months) and early (before 9 months) immunization strategies under field conditions. RESULTS: Highest measles incidence rates were observed among children <1 year of age. Vaccine effectiveness estimates increased with age at vaccination from 78% with a single dose administered at 6 months of age to 95% at 9 months. Vaccine effectiveness with the early two dose strategy was 93%. CONCLUSIONS: Immunization with a single dose of standard titer Schwarz vaccine before 9 months of age provided higher clinical protection than expected from seropositivity studies. The early two dose strategy is justified in contexts where measles incidence is high before 9 months of age. Our results raise the issue of lowering the recommended age for measles vaccination in developing countries.

[Bronchogenic cysts and their atypical localizations. A case of pleuro-diaphragmatic cyst]. / Les kystes bronchogéniques et leurs localisations atypiques. Une observation de kyste pleuro-diaphragmatique.

Bronchogenic cysts represent about 10 p. 100 of all surgical tumours of the mediastinum. They can never be diagnosed with absolute certainty prior to the operation, but when they arise in their typical sites, they can be suspected with a high probability. However, they can occur in very atypical sites, in which case the diagnosis remains very hypothetical until the operation. The authors report a case of a cyst which developed under the diaphragmatic pleura, in direct contact with the dome of the diaphragm and attached to the mediastinum by a fine vascular pedicle which inserted in the root of the triangular ligament.

[Pulmonary xanthogranulomas (author's transl)]. / Xanthogranulomes pulmonaires.

The authors report on six cases of pulmonary xanthogranuloma. They stress the latent character of these dense, round isolated parenchymatous tumors. The tumors have an homogeneous aspect without calcifications and regional adenopathies. The radio-clinical diagnosis is difficult to assess because the para-clinical examinations are regularly negative. The differential diagnosis is made either clinically, especially with hamartochondroma and peripheral cancer, or histologically according to the predominance of various types of cells, especially with a solitary plasmocytoma, a lymphoma or a sclerosant hemangioma. Histology is the only key to diagnosis. For these reasons, the decision for surgical intervention presents a problem as the patients, often young, present no visible signs and the lesions evolve but very slowly.