Optical bandgap engineering in nonlinear silicon nitride waveguides

Silicon nitride is awell-established material for photonic devices and integrated circuits. It displays a broad transparency window spanning from the visible to the mid-IR and waveguides can be manufactured with low losses. An absence of nonlinear multi-photon absorption in the erbium lightwave communications band has enabled various nonlinear optic applications in the past decade. Silicon nitride is a dielectric material whose optical and mechanical properties strongly depend on the deposition conditions. In particular, the optical bandgap can be modified with the gas flow ratio during low-pressure chemical vapor deposition (LPCVD). Here we show that this parameter can be controlled in a highly reproducible manner, providing an approach to synthesize the nonlinear Kerr coefficient of the material. This holistic empirical study provides relevant guidelines to optimize the properties of LPCVD silicon nitride waveguides for nonlinear optics applications that rely on the Kerr effect

THE ROLE OF QMS IN THE RELATIONSHIP BETWEEN INNOVATION CLIMATE AND PERFORMANCE

The emergence of new global competitors, the convergence of high-technology industries and the increasing speed and cost of technological development promise an increasingly uncertain environment for organizations, making adaptation to changes in the environment a central theme in the study of the organization for both organization theory and strategic management. This paper is thus seeks principally to verify that, while innovation and QM alone do not possess the qualities required to provide organizations with sustainable competitive advantages, the bundle of innovation and QM together with other resources and competencies will allow organizations to obtain a competitive advantage and adapt to their environment. The results show that the factors determining innovation—such as resistance to change, cohesion, and workload pressures—have repercussions for the firms’ capacity to adapt to their environment, and that a QM context facilitates this adaptation. Finally, we can conclude that a climate of support for innovation is positively related to the organization’s performance

Un estudio empírico del impacto de las iniciativas actuales de gestión de la calidad sobre la innovación y flexibilidad organizativa

In recent years, managers have opted for implementing Quality Management in their firms. The market offers different alternatives for QM implementation (EFQM, ISO, Six Sigma, etc.). Benefits of each initiative, varies from case to case. This article designs a criterion for choosing among four alternatives (Quality Control, EFQM, Six Sigma and ISO 9000), according to the different effects that QM elements included in each initiative, have on innovation and flexibility capabilities. To do so, using a stepwise regression with dummy variables, it analyses 234 European organizations. The research concludes that QM elements included on Quality Control and ISO standards have the same effect on administrative and technical innovation, and operational and strategic flexibility. QM elements included in EFQM model have a deeper impact on administrative and technical innovation, and strategic flexibility. And finally, QM elements included in Six Sigma methodology have a deeper impact on operational flexibility

High-Power Broadly Tunable Electrooptic Frequency Comb Generator

Broadband traveling-wave electrooptic modulators made of lithium niobate have reached a high level of technological maturity. They can provide simultaneously low V pi, sustain high power (both optical and RF) and yet provide low propagation loss. By combining together these features, we present a high-power handling, broadly tunable, electrooptic frequency comb generator. The device produces between 60 and 75 lines within -10 dB bandwidth over its full tuning range-from 6 to 18 GHz- and can handle up to 1 W of optical input power. This optical frequency comb platform is very well suited for applications in RF photonics and optical communications that require independent RF and optical tuning as well as high-repetition rates but moderate bandwidth

Hypogammaglobulinemia in BLT Humanized Mice – An Animal Model of Primary Antibody Deficiency

Primary antibody deficiencies present clinically as reduced or absent plasma antibodies without another identified disorder that could explain the low immunoglobulin levels. Bone marrow-liver-thymus (BLT) humanized mice also exhibit primary antibody deficiency or hypogammaglobulinemia. Comprehensive characterization of B cell development and differentiation in BLT mice revealed other key parallels with primary immunodeficiency patients. We found that B cell ontogeny was normal in the bone marrow of BLT mice but observed an absence of switched memory B cells in the periphery. PC-KLH immunizations led to the presence of switched memory B cells in immunized BLT mice although plasma cells producing PCor KLH- specific IgG were not detected in tissues. Overall, we have identified the following parallels between the humoral immune systems of primary antibody deficiency patients and those in BLT mice that make this in vivo model a robust and translational experimental platform for gaining a greater understanding of this heterogeneous array of humoral immunodeficiency disorders in humans: (i) hypogammaglobulinemia; (ii) normal B cell ontogeny in bone marrow; and (iii) poor antigen-specific IgG response to immunization. Furthermore, the development of strategies to overcome these humoral immune aberrations in BLT mice may in turn provide insights into the pathogenesis of some primary antibody deficiency patients which could lead to novel clinical interventions for improved humoral immune function

Epidemiology of influenza-like illness in the Amazon Basin of Peru, 2008-2009.

BackgroundData addressing the incidence and epidemiology of influenza and influenza-like illness (ILI) in tropical regions of the world is scarce, particularly for the neotropics of South America.MethodsWe conducted active, population-based surveillance for ILI across 45 city blocks within the Amazon Basin city of Iquitos, Peru. Demographic data and household characteristics were collected for all participants, and participating households were visited three times weekly to inquire about ILI (fever plus cough or sore throat) among household residents. Nasal and oropharyngeal swabs were collected from participants with ILI and tested for influenza virus infection.ResultsBetween May 1, 2008 and July 8, 2009, we monitored 10,341 participants for ILI for a total of 11,569.5 person-years. We detected 459 ILI episodes, with 252 (54.9%) of the participants providing specimens. Age-adjusted incidence of ILI was estimated to be 46.7 episodes/1000 person-years. Influenza A and B viruses were detected in 25 (9.9%) and 62 (24.6%) specimens of ILI patients, respectively, for an estimated age-adjusted incidence rate of 16.5 symptomatic influenza virus infections/1000 person-years. Risk factors for ILI included age, household crowding, and use of wood as cooking fuel. For influenza virus infection specifically, age and use of wood as a cooking fuel were also identified as risk factors, but no effect of household crowding was observed.ConclusionsOur results represent the initial population-based description of the epidemiology of ILI in the Amazon region of Peru, which will be useful for developing region-specific strategies for reducing the burden of respiratory disease