Micromirror structured illumination microscope for high-speed in vivo drosophila brain imaging.

Genetic tools and especially genetically encoded fluorescent reporters have given a special place to optical microscopy in drosophila neurobiology research. In order to monitor neural networks activity, high speed and sensitive techniques, with high spatial resolution are required. Structured illumination microscopies are wide-field approaches with optical sectioning ability. Despite the large progress made with the introduction of the HiLo principle, they did not meet the criteria of speed and/or spatial resolution for drosophila brain imaging. We report on a new implementation that took advantage of micromirror matrix technology to structure the illumination. Thus, we showed that the developed instrument exhibits a spatial resolution close to that of confocal microscopy but it can record physiological responses with a speed improved by more than an order a magnitude.

[Should we reconstruct the flexor retinaculum in the carpal tunnel?]. / Faut-il reconstruire le rétinaculum des fléchisseurs (retinaculum flexorum) dans le canal carpien?

Conflicting data in the literature justify this review about the flexor retinaculum (FR). Reconstruction of the FR following carpal tunnel open release has been recommended in order to limit the drawbacks of open carpal tunnel release; these drawbacks have been reported in wide series of results published between 1956 and 1988. This paper includes a review of the literature, a survey of the practice of the members of the French society for surgery of the hand (GEM), a self-evaluation of grip strength as well as a summary of indications.

[Multicentric study of thrombosis prevention in upper-extremity microsurgery. Survey at the Fesum centers]. / Etude multicentrique sur la prévention de la thrombose en microchirurgie du membre supérieur. Enquête auprès de la Fesum.

Thrombosis is still the first cause of microsurgery failure. Lots of publications have been made but no consensus exists. We first analysed the results of our study in 53 French expert surgeons, then we compared them with the last published datas, most of all, with the similar surveys. If a big majority (81 %) of the surgeons use a preventing method, we observed majors variations between them and also compared to the anglosaxons surgeons habits. This survey permits to make the point on today's practice and to show that some of them are based on low proof level and something even done without any medical references. After datas analysis, we observed that none of the medical treatments proved efficiency on preventing vascular thrombosis. The low molecular weight heparins (LMWH) could be used on postops without increase bleeding but not to lower specially the microvascular thrombosis rate. Aspirin did not improve the positive rates and its adjonction to LMWH increased the bleeding. Until scientific studies prove efficacy of a treatment, the surgeon has to make a personal choice: keeping habits or following evidence-based medicine.

Single molecule study of perylene orange photobleaching in thin sol-gel films.

The paper reports on photobleaching mechanisms of perylene orange embedded in thin sol-gel films, derived from single molecule studies. The experimental configuration uses wide-field illumination and one photon excitation of the molecules. Measurements have been performed both at ambient conditions and under vacuum in order to get information on the influence of oxygen on photobleaching in such porous samples. We have also recorded the evolution of photobleaching with respect to the excitation intensity. The results demonstrate that photobleaching from excited states higher than the first singlet and triplet states has a nonnegligible contribution as soon as the excitation energy exceeds a few hundred W/cm2 and that this process is favored in the presence of air. The study also demonstrates that perylene orange in sol-gel films is not a very efficient emitter but that photobleaching can be slow, which explains the interest for perylene orange as a good candidate to produce long lifetime solid-state lasers when embedded in monoliths of sol-gel.

Specific Raman signatures of a dimetallofullerene peapod.

We report on the Raman spectroscopy of a dimetallofullerene peapod, (La(2)@C(80))(m)@SWNT. Drastic changes are observed with respect to pristine nanotubes. A sharp intense line at 142 cm(-1) is interpreted as a signature of polymerization of the encapsulated metallofullerenes. Additional strong signatures appear at about 400, 520, and 640 cm(-1), respectively. Their intensity suggests the existence of an enhancement effect. The stiffening and the up-shift of the G-band modes appear to imply that a charge transfer process between the nanotube and the peas occurs.

Optical contrast in apertureless microscopy.

We report on optical image contrast for a specific apertureless near-field optical microscope. We demonstrate that the main part of the optical image's contrast results from the sample's topography. The coupling mechanism is analyzed, and we show that the microscope can be regarded as an interferometer that sensitively detects near-field components. However, in the basic configuration the reference field of the interferometer is coupled to the topography. Finally, it is demonstrated that, by controlling the phase of the reference field, one can largely decorrelate the optical image from the topography.

Field enhancement and apertureless near-field optical spectroscopy of single molecules.

We report on fluorescence enhancement in near field optical spectroscopy by apertureless microscopy. Our apertureless microscope is designed around a confocal fluorescence microscope associated with an AFM head. First, we show that the confocal microscope alone allows single molecule imaging and single molecule fluorescence analysis. When associated with the AFM head, we demonstrate, for the first time to our knowledge, that single molecule fluorescence is enhanced under the silicon tip. We tentatively attribute this effect to field enhancement under the tip.

Field cross correlator for analysis of ultrafast signals.

The cross-correlation function between two light fields is recorded with the help of a new device. The proposed correlator exhibits ultrashort time resolution. The optical path difference between the two interfering beams does not have to be known with interferometric precision. The experimental dynamic range proved to be as large as 10(5). The device features imaging capabilities that could be applied to the analysis of two-dimensional images with ultrashort time resolution.