No abstract

Aperture, attenuation, and far-field radiation diagrams have been studied on short lengths of commercial polymethyl methacrylate- (PMMA-) core optical fibers. The spectral attenuation of the PMMA constituting the core has been carefully measured and compared with the attenuation that may be calculated from optical properties of PMMA. Accurate extrinsic attenuation spectra have been obtained. Moreover, the dependence of the far-field radiation diagram on the fiber length and on the launching incidence of a laser beam has been studied on this side of the mode-equilibrium length. The analysis of these diagrams, first performed with the Gloge mode-coupling model, has been improved with the hypothesis that the mode-coupling processes are a result of light diffraction by structural anomalies in the core. The average size and form of these structural anomalies has been evaluated. They may be longitudinal microcracks of the PMMA coming from stress relaxation, which occurs during the fiber-drawing process.

The objective of this study was to assess the level of macrocyclic trichothecenes (MCT), one of the most potent mycotoxins, on wall surfaces, floor dust and air samples from moldy dwellings. The study was based on an index group comprising 15 flooded dwellings contaminated by Stachybotrys chartarum or Chaetomium and a control group comprising nine dwellings without molds on visual inspection and mold sampling. Three samples were collected from each dwelling: a sample from the moldy wall, using a swab, a floor dust sample on a 0.5 m(2) surface with a cloth and an air sample using a pump comprising a 1 microm Teflon filter. The MCT level was measured using a monoclonal, antibody-based ELISA test. Compared with measurements performed in index dwellings, higher MCT values were measured on floor dust samples from moldy dwellings (P = 0.02). Samples from wall surfaces demonstrated nearly significant differences (P = 0.06). No significant differences were observed for air samples (P = 0.15), but some samples showed increased MCT levels. Significant correlations were observed between the levels measured on wall surfaces, floor dust and air samples (P = 0.02 to 0.05). In contrast, no correlation was observed between moldy surface and MCT levels. In conclusion, this paper reports for the first time direct evidence for the presence of MCT in moldy dwellings.