Determination of the fundamental absorption and optical bandgap of dielectric thin films from single optical transmittance measurements.

In this work, we propose a method to retrieve the thickness and optical constants of dielectric thin films from single optical transmittance measurements. The method is based on the envelope method and requires a simple dispersion model for the real part of the refractive index with few fitting parameters, while the absorption coefficient can be determined without the aid of a dispersion model. The wavelength-dependent optical constants can be obtained even from spectra that exhibit few interference fringes. We have tested the method with simulated and real transmittance data from thin films in the spectral range covering the fundamental absorption. In order to assess the method's reliability to retrieve the optical constants and optical bandgap, a comparison is performed with the method by Chambouleyron, known as the Pointwise Unconstrained Minimization Approach, and a fit using the Cody-Lorentz dispersion model. We evaluate the methods' capability to retrieve the fundamental absorption and optical bandgap, and their compromise with film thickness accuracy. Finally, the methods are tested and contrasted using optical transmittance of three different semiconductor material thin films.

Predictive value of hypoxia in advanced head and neck cancer after treatment with hyperfractionated radio-chemotherapy and hypoxia modification

Purpose. Hypoxia has predictive value in head and neck cancer (HNC). It has been well described, albeit in a small number of clinical Centres. The aim of this study was to describe our experience using the polarographic probe technique to assess the predictive value of tumour oxygenation in patients with advanced HNC treated with hyperfractionated radio-chemotherapy. Hypoxia modification was induced using percutaneous spinal cord stimulation (SCS). Methods/patients. Male patients (n = 12; stage IVb n = 8; IVa n = 4; mean age 58: range 46-70 years) with advanced HNC were evaluated. Planned therapy was hyperfractionated-radiotherapy, oral tegafur (precursor of 5-fluorouracil) and hypoxia modification using SCS. Pre-treatment analyses included: haemoglobin levels and tumour oxygenation (using the Eppendorf polarographic probe device). Oxygenation was expressed as median-pO2 (in mmHg) and hypoxia as the percentage of pO2 values ≤5 mmHg (HP5) and ≤2.5 mmHg (HP2.5). Results. Lower haemoglobin levels were directly correlated with median pO2 (p = 0.017) and inversely correlated with HP5 (p = 0.020) and more advanced stages (IVb vs. IVa; p = 0.028). Patients who subsequently developed systemic metastasis had tumours that were more hypoxic, with lower median pO2 (p = 0.036) and higher HP5 (p = 0.036). The subgroup of patients with HP2.5 above the median (the most hypoxic tumours) had lower loco-regional control (p = 0.027), cause-specific survival (p = 0.008), and overall survival (p = 0.008). Conclusions. Higher tumour hypoxia showed predictive value in HNC in our study, and was significantly associated with lower overall survival, cause-specific survival, and loco-regional control. Tumour hypoxia determination could be used to select patients who would most benefit by hypoxia modification during chemo-radiotherapy of HNC (AU)

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Predictive value of hypoxia in advanced head and neck cancer after treatment with hyperfractionated radio-chemotherapy and hypoxia modification.

PURPOSE: Hypoxia has predictive value in head and neck cancer (HNC). It has been well described, albeit in a small number of clinical Centres. The aim of this study was to describe our experience using the polarographic probe technique to assess the predictive value of tumour oxygenation in patients with advanced HNC treated with hyperfractionated radio-chemotherapy. Hypoxia modification was induced using percutaneous spinal cord stimulation (SCS). METHODS/PATIENTS: Male patients (n = 12; stage IVb n = 8; IVa n = 4; mean age 58: range 46-70 years) with advanced HNC were evaluated. Planned therapy was hyperfractionated-radiotherapy, oral tegafur (precursor of 5-fluorouracil) and hypoxia modification using SCS. Pre-treatment analyses included: haemoglobin levels and tumour oxygenation (using the Eppendorf polarographic probe device). Oxygenation was expressed as median-pO2 (in mmHg) and hypoxia as the percentage of pO2 values ≤5 mmHg (HP5) and ≤2.5 mmHg (HP2.5). RESULTS: Lower haemoglobin levels were directly correlated with median pO2 (p = 0.017) and inversely correlated with HP5 (p = 0.020) and more advanced stages (IVb vs. IVa; p = 0.028). Patients who subsequently developed systemic metastasis had tumours that were more hypoxic, with lower median pO2 (p = 0.036) and higher HP5 (p = 0.036). The subgroup of patients with HP2.5 above the median (the most hypoxic tumours) had lower loco-regional control (p = 0.027), cause-specific survival (p = 0.008), and overall survival (p = 0.008). CONCLUSIONS: Higher tumour hypoxia showed predictive value in HNC in our study, and was significantly associated with lower overall survival, cause-specific survival, and loco-regional control. Tumour hypoxia determination could be used to select patients who would most benefit by hypoxia modification during chemo-radiotherapy of HNC.

Plasmacytoid dendritic cell-derived IFNα modulates Th17 differentiation during early Bordetella pertussis infection in mice.

Whooping cough is a highly contagious respiratory disease caused by Bordetella pertussis (B. pertussis). T helper 17 (Th17) cells have a central role in the resolution of the infection. Emerging studies document that type I interferons (IFNs) suppress Th17 differentiation and interleukin (IL)-17 responses in models of infection and chronic inflammation. As plasmacytoid dendritic cells (pDCs) are a major source of type I IFNs, we hypothesize that during B. pertussis infection in mice, pDC-derived IFNα inhibits a rapid increase in Th17 cells. We found that IFNα-secreting pDCs appear in the lungs during the early stages of infection, while a robust rise of Th17 cells in the lungs is detected at 15 days post-infection or later. The presence of IFNα led to reduced Th17 differentiation and proliferation in vitro. Furthermore, in vivo blocking of IFNα produced by pDCs during infection with B. pertussis infection resulted in early increase of Th17 frequency, inflammation, and reduced bacterial loads in the airways of infected mice. Taken together, the experiments reported here describe an inhibitory role for pDCs and pDC-derived IFNα in modulating Th17 responses during the early stages of B. pertussis infection, which may explain the prolonged nature of whooping cough.