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Rationale: Obesity hypoventilation syndrome (OHS) has been associated with cardiac dysfunction. However, randomized trials have assessing the impact of long-term noninvasive ventilation (NIV) or CPAP on cardiac structure and function assessed by echocardiography are lacking. Methods: In a pre-specified secondary analysis of the largest multicenter randomized controlled trial of OHS〔Pickwick project, n=221 patient with OHS and coexistent severe obstructive sleep apnea (OSA)〕, we compared the effectiveness of 3 years of NIV and CPAP on structural and functional echocardiographic changes. At baseline and annually during 3 sequential years patients underwent transthoracic two-dimensional and doppler echocardiography. Echocardiographers were blinded to the treatment allocation. Statistical analysis was performed using a linear mixed-effects model with a treatment group/repeated measures interaction to determine the differential effect between CPAP and NIV. Results:196 patients were analyzed, 102 treated with CPAP and 94 treated with NIV. Systolic pulmonary artery pressure decreased from 40.5±1.47 mmHg at baseline to 35.3±1.33 mmHg at 3 years with CPAP and from 41.5±1.56 mmHg to 35.5±1.42 with NIV (p Conclusion: In patients with OHS and concomitant severe OSA, long-term treatment with NIV and CPAP led to similar degrees of improvement in pulmonary hypertension and LVDF.

Rationale: Obesity hypoventilation syndrome (OHS) is commonly treated with noninvasive ventilation (NIV) or CPAP. NIV is more complex and costly but provides ventilatory support. To date there have been no long-term or cost trials comparing these treatment modalities. Methods: We performed a large, randomized, multicenter, open-label controlled trial in Spain to compare the long-term effectiveness of NIV and CPAP using hospitalization days/year-patient as the primary end point. We carried out a simple cost analysis including effectiveness cost during 3 year of follow-up. We included the following cost groups: visits, adjustment of NIV, tests, medication, therapies and hospital resources utilization. A sensitivity analysis was conducted according to 3 different scenarios guided by the International Gross Domestic Product. Results: In total, 215 patients with untreated OHS and severe obstructive sleep apnea (OSA) were randomized to NIV or CPAP therapy and followed at least 3 years. The effectiveness was close between arms (mean difference NIV-CPAP: -0.19, 95% CI -1.13 to 0.75). The cost per patient/year was lower in the CPAP arm (1,898.2€; SD 1939.5) than the cost in the NIV arm (2,809.3€; SD 2901.6), mean difference -911.1€ (p Conclusions: In stable patients with OHS and severe OSA, despite NIV having a slight advantage in effectiveness, CPAP could be considered the first line of treatment due to its lower cost but, a case-by-case assessment is recommended to detect patients who would benefit from a switch to NIV.

Rationale: Obesity hypoventilation syndrome (OHS) is commonly treated with CPAP or noninvasive ventilation (NIV). NIV is more complex and costly but it provides ventilatory support. To date there have been no long-term trials comparing these treatment modalities. Methods: We performed a large, multicenter, open-label controlled trial in Spain to compare the long-term effectiveness of NIV and CPAP: respiratory function, Epworth sleepness scale (ESS), other clinical symptoms, blood pressure (BP) and health related quality of life (HRQL). The analysis was performed according to the intention-to-treat principle. Results: In total, 215 patients with untreated OHS and severe obstructive sleep apnea (OSH) were randomized to NIV or CPAP therapy and followed at least 3 years. PaCO2, bicarbonate and pH improved significantly with both treatments without group differences. FEV1 and FVC improved with positive airway pressure (PAP) but without significant group differences. The 6-MWD test did not improve with either PAP modality and there were no significant group differences. ESS and other clinical symptoms like dyspnea or unrefreshing sleep improved similarly with CPAP and NIV therapy. Both systolic and diastolic BP improved significantly with PAP but without group differences. HRQL tests (SF-36 physical and mental, FOSQ and VAWS) improved with PAP without any significant group differences. Conclusions: In stable patients with OHS and severe OSA, NIV and CPAP have similar long-term effectiveness improving respiratory function, symptoms, BP and HRQL. Given that CPAP has lower complexity and cost, CPAP may be the preferred treatment modality until more studies become available.

Degradation of high power laser diodes is related to defect formation in the active parts of the laser. Extended defects can develop both at the facets, and inside the cavity. Their characterization is necessary for understanding the mechanisms driving the degradation. Cathodoluminescence is very useful for studying defects in degraded lasers. The main degradation mechanisms are discussed, supported by a thermomechanical model.

Introduction Home respiratory polygraphy (HRP) is a cost-effectiveness choice to polysomnography (PSG) for diagnosis and treatment in patients with high obstructive sleep apnea (OSA) suspicion what includes 40% of patients needing sleep study. There is not randomized control trial (RCT) focus in the same objective including the entire population needing sleep study (intermediate-high OSA suspicion). Objectives Demonstrate if HRP is a non-inferior effective and a cost-effective alternative to PSG for diagnosis and treatment in most OSA suspicion patients. Method A multicentric, non-inferiority RCT included patients with intermediate-to-high OSA suspicion from 8 centers in Spain. Patients were randomized to be managed (diagnosis and treatment decision-marking) according to PSG or HRP results for 6 months of follow-up. Sleep and quality of life questionnaires, ambulatory 24 hours blood pressure monitoring, CPAP compliance, PSG at 6 months and side effects were collected. An Epworth scale inter-group difference less than -2 in the lower bound of 1-side 95% CI was the non-inferiority premise. QALYS changes were used in a Bayesian cost-effectiveness analysis. Results 430 patients were randomized. At 6 months, changes in the Epworth scale, EuroQol, SF36, FOSQ, analogical scale, PSG and blood pressure were similar between groups. Epworth scale non-inferiority premise was -0.24 adjusted by baseline values and sites. In the cost-effectiveness plane, HRP had similar effectiveness (QALYS different -0.0043) and 421€ lower cost than PSG. Conclusion In this large RCT, HRP was a clear cost-effectiveness alternative to PSG for management of most patients with OSA suspicion. Present results can decrease costs and waiting list across countries.

The era of the seed-cast grown monocrystalline-based silicon ingots is coming. Mono-like, pseudomono or quasimono wafers are product labels that can be nowadays found in the market, as a critical innovation for the photovoltaic industry. They integrate some of the most favorable features of the conventional silicon substrates for solar cells, so far, such as the high solar cell efficiency offered by the monocrystalline Czochralski-Si (Cz-Si) wafers and the lower cost, high productivity and full square-shape that characterize the well-known multicrystalline casting growth method. Nevertheless, this innovative crystal growth approach still faces a number of mass scale problems that need to be resolved, in order to gain a deep, 100% reliable and worldwide market: (i) extended defects formation during the growth process; (ii) optimization of the seed recycling; and (iii) parts of the ingots giving low solar cells performance, which directly affect the production costs and yield of this approach. Therefore, this paper presents a series of casting crystal growth experiments and characterization studies from ingots, wafers and cells manufactured in an industrial approach, showing the main sources of crystal defect formation, impurity enrichment and potential consequences at solar cell level. The previously mentioned technological drawbacks are directly addressed, proposing industrial actions to pave the way of this new wafer technology to high efficiency solar cells. Copyright © 2012 John Wiley & Sons, Ltd.

Raman scattering and point contact current-voltage (PCIV) measurements were used as characterization tools of tin-diffused GaAs layers. Diffusion was induced by irradiating GaAs substrates covered with thin tin layers single pulses of a ruby laser. Samples processed with the lowest energies show strong damage and incomplete electrical activation as deduced from Raman and PCIV measurements, respectively. Raman microprobe in depth analysis and PCIV profiles also suggest the presence of a damaged region with incomplete electrical activation at the boundary between the molten layer and the solid substrate.

The influence of the quantum well (QW) interfaces with the barrier layers on the rapid degradation of AlGaAs based high power laser bars (808 nm) is investigated. Thermal stresses induced in the device by the local heating produced by nonradiative recombination areas at the facet mirror are calculated by means of a thermomechanical model. Results show that the laser power density threshold necessary to achieve the plastic deformation, leading to the generation of dislocations and to the failure of these devices, is reduced as the quality of the QW interfaces worsens in terms of thermal boundary resistance.

A thermomechanical model for the mechanism of rapid degradation of AlGaAs based high power laser bars (808 nm) is presented. Thermal stresses induced in the device by local heating around a facet defect by nonradiative recombination and self-absorption of photons are calculated, as well as the conditions for the beginning of plastic deformation, when these thermal stresses overcome the yield strength. The values of the power density and of the local temperature at which the yield limit is surmounted are in agreement with the threshold values for the degradation of Al based lasers given in the literature. The present model can also elucidate the role played by the packaging stress, being able to explain how this stress reduces the optical power density threshold for failure of these lasers.