Co-axial dual-core resonant leaky fibre for optical amplifiers

We present a co-axial dual-core resonant leaky optical fibre design, in which the outer core is made highly leaky. A suitable choice of parameters can enable us to resonantly couple power from the inner core to the outer core. In a large-core fibre, such a resonant coupling can considerably increase the differential leakage loss between the fundamental and the higher order modes and can result in effective single-mode operation. In a small-core single-mode fibre, such a coupling can lead to sharp increase in the wavelength dependent leakage loss near the resonant wavelength and can be utilized for the suppression of amplified spontaneous emission and thereby gain equalization of an optical amplifier. We study the propagation characteristics of the fibre using the transfer matrix method and present an example of each, the large-mode-area design for high power amplifiers and the wavelength tunable leakage loss design for inherent gain equalization of optical amplifiers.Comment: 6 page

Fatores que influenciam o acesso aos serviços de saúde na visão de profissionais e usuários de uma unidade básica de referência

O objetivo deste trabalho foi analisar o acesso de usuários de uma Unidade Básica de Referência (UBR) aos serviços de saúde de um município da região Metropolitana de Belo Horizonte, Minas Gerais. Foram realizadas entrevistas semiestruturadas com 15 profissionais de saúde e aplicado questionário semiestruturado a 38 usuários. As entrevistas abordaram características do atendimento local, da equipe de saúde, dos usuários e da rede prestadora de serviços de saúde. Os questionários abordaram características sociodemográficas e de saúde dos usuários. A análise dos resultados das entrevistas e questionários foi apresentada com base nas dimensões estrutural (financiamento, cobertura), relacional (compreensão do processo saúde-doença) e operacional (organização dos serviços). Na dimensão estrutural, verificou-se que o subfinanciamento do sistema de saúde constitui uma dificuldade para o acesso aos serviços de saúde e para a implantação da Estratégia Saúde da Família (ESF); na dimensão relacional, a ausência de alinhamento sobre a estrutura e os fluxos de funcionamento do sistema de saúde impacta negativamente na relação do profissional com o usuário; e na dimensão operacional, profissionais de saúde e usuários relataram importantes lacunas tais como cobertura da ESF, marcação de consulta, acolhimento, barreiras geográficas, referência e contrarreferência. As informações obtidas neste trabalho são importantes para compreender os fatores que influenciam o acesso aos serviços de saúde da população estudada e colaborar para o desenvolvimento de estratégias voltadas para melhoria do acesso

Extracting fluorescent reporter time courses of cell lineages from high-throughput microscopy at low temporal resolution

The extraction of fluorescence time course data is a major bottleneck in high-throughput live-cell microscopy. Here we present an extendible framework based on the open-source image analysis software ImageJ, which aims in particular at analyzing the expression of fluorescent reporters through cell divisions. The ability to track individual cell lineages is essential for the analysis of gene regulatory factors involved in the control of cell fate and identity decisions. In our approach, cell nuclei are identified using Hoechst, and a characteristic drop in Hoechst fluorescence helps to detect dividing cells. We first compare the efficiency and accuracy of different segmentation methods and then present a statistical scoring algorithm for cell tracking, which draws on the combination of various features, such as nuclear intensity, area or shape, and importantly, dynamic changes thereof. Principal component analysis is used to determine the most significant features, and a global parameter search is performed to determine the weighting of individual features. Our algorithm has been optimized to cope with large cell movements, and we were able to semi-automatically extract cell trajectories across three cell generations. Based on the MTrackJ plugin for ImageJ, we have developed tools to efficiently validate tracks and manually correct them by connecting broken trajectories and reassigning falsely connected cell positions. A gold standard consisting of two time-series with 15,000 validated positions will be released as a valuable resource for benchmarking. We demonstrate how our method can be applied to analyze fluorescence distributions generated from mouse stem cells transfected with reporter constructs containing transcriptional control elements of the Msx1 gene, a regulator of pluripotency, in mother and daughter cells. Furthermore, we show by tracking zebrafish PAC2 cells expressing FUCCI cell cycle markers, our framework can be easily adapted to different cell types and fluorescent markers