[What is the value of the chest radiography in making the diagnosis of children pneumonia in 2011?]. / Quel est l'intérêt de la radiographie du thorax dans le diagnostic d'une pneumonie de l'enfant en 2011 ?

UNLABELLED: According to the French national health authority guidelines, the diagnosis of childhood pneumonia is based on clinical suspicion and radiological confirmation. The chest radiography is an expensive procedure, and potentially deleterious by its radiating character. We have attempted to clarify its diagnostic value in community acquired pneumonia in children through a literature review using the Pubmed search engine with the following keywords: "pneumonia, child, radiograph". CONCLUSION: The indication of chest radiography in severe pneumonia achieved unanimity among the various scientific societies. In contrast, in mild forms, tendency of the available data is to not recommend the routine use of chest radiography; further randomised and prospective studies are necessary to confirm this trend. Finally, because of the frequency of atypical presentations in children, chest radiography retains all its usefulness in the etiologic diagnosis of fever of unknown origin.

Towards noninvasive molecular fluorescence imaging of the human brain.

Fluorescence molecular brain imaging is a new modality allowing the detection of specific contrast agents down to very low concentration ranges (picomolar) in disease models. Here we demonstrate a first noninvasive application of fluorescence imaging in the human brain, where concentrations down to about 100 nM of a nonspecific dye were detected. We argue that due to its high sensitivity, optical molecular imaging of the brain is feasible, which - together with its bedside applicability - makes it a promising technique for use in patients.

Filamentation of femtosecond light pulses in the air: turbulent cells versus long-range clusters.

The filamentation of ultrashort pulses in air is investigated theoretically and experimentally. From the theoretical point of view, beam propagation is shown to be driven by the interplay between random nucleation of small-scale cells and relaxation to long waveguides. After a transient stage along which they vary in location and in amplitude, filaments triggered by an isotropic noise are confined into distinct clusters, called "optical pillars," whose evolution can be approximated by an averaged-in-time two-dimensional (2D) model derived from the standard propagation equations for ultrashort pulses. Results from this model are compared with space- and time-resolved numerical simulations. From the experimental point of view, similar clusters of filaments emerge from the defects of initial beam profiles delivered by the Teramobile laser facility. Qualitative features in the evolution of the filament patterns are reproduced by the 2D reduced model.

Multiple filamentation of terawatt laser pulses in air.

The filamentation of femtosecond light pulses in air is numerically and experimentally investigated for beam powers reaching several TW. Beam propagation is shown to be driven by the interplay between intense, robust spikes created by the defects of the input beam and random nucleation of light cells. Evolution of the filament patterns can be qualitatively reproduced by an averaged-in-time (2D+1)-dimensional model derived from the propagation equations for ultrashort pulses.

White-light filaments for atmospheric analysis.

Most long-path remote spectroscopic studies of the atmosphere rely on ambient light or narrow-band lasers. High-power femtosecond laser pulses have been found to propagate in the atmosphere as dynamically self-guided filaments that emit in a continuum from the ultraviolet to the infrared. This white light exhibits a directional behavior with enhanced backward scattering and was detected from an altitude of more than 20 kilometers. This light source opens the way to white-light and nonlinear light detection and ranging applications for atmospheric trace-gas remote sensing or remote identification of aerosols. Air ionization inside the filaments also opens promising perspectives for laser-induced condensation and lightning control. The mobile femtosecond-terawatt laser system, Teramobile, has been constructed to study these applications.