Laser line shape and spectral density of frequency noise

International audiencePublished experimental results show that single-mode laser light is characterized in the microwave range by a frequency noise which essentially includes a white part and a 1/f (flicker) part. We theoretically show that the spectral density (the line shape) which is compatible with these results is a Voigt profile whose Lorentzian part or homogeneous component is linked to the white noise and the Gaussian part to the 1/f noise. We measure semiconductor laser line profiles and verify that they can be fit with Voigt functions. It is also verified that the width of the Lorentzian part varies like 1/P where P is the laser power while the width of the Gaussian part is more of a constant. Finally, we theoretically show from first principles that laser line shapes are also described by Voigt functions where the Lorentzian part is the laser Airy function and the Gaussian part originates from population noise

Restricted expression of membrane type 1-matrix metalloproteinase by myofibroblasts adjacent to human breast cancer cells.

The membrane type-1 matrix metalloproteinase (MT1-MMP), a protease originally identified in breast carcinoma, is characterized by its capacity to activate other MMPs (MMP-2 and MMP-13) and to degrade extracellular matrix. Our study was undertaken to localize and identify the MT1-MMP expressing cells in human breast adenocarcinomas. A textural analysis of images obtained by immunohistochemistry and in situ hybridization showed precisely the co-expression of alpha smooth muscle actin (alphaSM actin) and MT1-MMP in myofibroblasts. MT1-MMP expression is confined to myofibroblasts in close contact with tumor cells. In sharp contrast, the expression of MMP-2 was more widely distributed in both alphaSM actin positive and negative cells close to and at distance from cancer cell clusters. Our in vitro observations are consistent with the higher level of MT1-MMP expression and of MMP-2 activation observed in alphaSM actin positive fibroblasts derived from breast tumors, as compared to normal breast fibroblasts. Collectively, these results implicate myofibroblasts as major producer of MT1-MMP in breast cancer and emphasize the importance of stromal-epithelial cell interactions in their progression

Late‐Onset Combined Immune Deficiency: A Subset of Common Variable Immunodeficiency with Severe T Cell Defect

Background. Common variable immunodeficiency (CVID) is a primary immune deficiency defined by defective antibody production. In most series, a small proportion of patients present with opportunistic infections (OIs). Methods.The French DEFI study has enrolled patients with primary hypogammaglobulinemia and allows a detailed clinical and immunologic description of patients with previous OIs and/or at risk for OIs. Results.Among 313 patients with CVID, 28 patients (8.9%) presented with late-onset combined immune deficiency (LOCID), defined by the occurrence of an OI and/or a CD4+T cell count < 200×106cells/L, and were compared with the remaining 285 patients with CVID. The patients with LOCID more frequently belonged to consanguineous families (29% vs 8%; P=.004). They differed from patients with CVID with a higher prevalence of splenomegaly (64% vs 31%), granuloma (43% vs 10%), gastrointestinal disease (75% vs 42%), and lymphoma (29% vs 4%). Even on immunoglobulin substitution, they required more frequent antibiotics administration and hospitalization. Lymphocyte counts were lower, with a marked decrease in CD4+T cell counts (158×106vs 604×106cells/L; P<.001) and a severe defect in naive CD45RA+CCR7+CD4+T cell counts (<20% of total CD4+T cells in 71% of patients with LOCID vs 37% of patients with CVID; P=.001). The CD19+B cell compartment was also significantly decreased (20×106vs 102×106cells/L; P<.001). Conclusions.LOCID differs from classic CVID in its clinical and immunologic characteristics. Systematic T cell phenotype may help to discriminate such patients from those with CVID. Identification of this phenotype should result in a more fitted diagnostic and therapeutic approach of infections and could provide insights for genetic diagnosis