Severe disseminated mycobacterial infection in a boy with a novel mutation leading to IFN-γR2 deficiency

Mendelian susceptibility to mycobacterial diseases (MSMD) is a rare syndrome characterized by predisposition to severe, sometimes lethal, disease caused by otherwise poorly virulent mycobacteria. We report here a boy with a recurrent mycobacterial infection from the age of five months. Immunological analyses revealed an inability to respond to IFN-γ, subsequent genetic analyses revealed a novel homozygous mutation, r.679G > A in the IFNGR2 gene, resulting in a G227R substitution, that caused IFN-γR2 deficiency. This is only the 8th mutation in IFN-γR2 known so far. The boy eventually died of hepatic coma due to liver failure at the age of five.

Optical feedback effects in Nd-doped fiber lasers with broadband spectra

A detailed experimental and theoretical investigation of optical feedback effects in Nd-doped fiber lasers is presented. Of particular interest is an output-intensity reduction attributed to the broadband nature of the laser spectrum combined with a mode-selection mechanism of the external Fabry-Perot cavity. The theoretical approach, based on a simple multimode rate-equation model, provides an excellent description of the experimental results.

Output-coupling optimization of Nd-doped fiber lasers

A simple theoretical modeling of the static properties of a fiber laser that includes distributed losses and inhomogeneous pumping is presented. Closed-form expressions for both the output and the backward (at the input mirror) intensities are obtained. The model is based on an extended formulation of the Rigrod's theory. It is shown that the laser responds differently depending on the length of the fiber. In particular, we show that for long (short) lasers optimal output power is achieved with low (high) output-coupler reflectivities. Experimental evidence of these results is obtained with Nd-doped fiber lasers with various lengths.

Feedback-induced polarization switching in a Nd-doped fiber laser

We demonstrate a switching effect between the two polarization eigenstates of a Nd-doped fiber laser when it is subjected to an optical feedback signal. Conditions for an optimization of this effect are recognized to depend on the relative orientation of the fiber eigenaxes and the polarization states of the pump and feedback beams.