Semiconductor laser mode locking stabilization with optical feedback from a silicon PIC

Semiconductor mode-locked lasers can be used in a variety of applications ranging from multi-carrier sources for WDM communication systems to time base references for metrology. Their packaging in compact chip- or module-level systems remains however burdened by their strong sensitivity to back-reflections, quickly destroying the coherence of the mode-locking. Here, we investigate the stabilization of mode-locked lasers directly edge coupled to a silicon photonic integrated circuit, with the objective of moving isolators downstream to the output of the photonic circuit. A 2.77 kHz 3 dB RF linewidth, substantially improved compared to the 15.01 kHz of the free running laser, is obtained in the best case. Even in presence of detrimental reflections from the photonic circuit, substantial linewidth reductions from 20 kHz to 8.82 kHz, from 572 kHz to 14.8 kHz, and from 1.5 MHz to 40 kHz are realized

COVID-19 e gestação: manifestações clínicas, alterações laboratoriais e desfechos maternos, uma revisão sistemática de literatura/COVID-19 and pregnancy: clinical manifestations, laboratorial alterations and maternal endpoints, a systematic review of the literature

INTRODUÇÃO: COVID-19 é uma doença decorrente da infecção pelo SARS-CoV-2, um novo tipo de coronavírus que teve seu primeiro caso na cidade de Wuhan, China, no final do ano de 2019. Esse vírus gerou a atual pandemia, que acometeu pessoas de todos os sexos e idades, inclusive as gestantes. Sabe-se que na gestação ocorrem inúmeras alterações fisiológicas e imunológicas. Por conta disso, a gestação parece representar um período de maior suscetibilidade a infecções virais. OBJETIVOS: Relatar quais são as principais manifestações clínicas, alterações laboratoriais e complicações maternas registradas até o momento em gestantes com COVID-19, com a finalidade de aprimorar a assistência à saúde do binômio mãe-feto nesse contexto de pandemia. METODOLOGIA: Trata-se de uma revisão sistemática realizada nas bases de dados PubMed Central® (PMC), Medical Literature Analysis and Retrievel System Online (Medline), Literatura Latino-americana e do Caribe em Ciências da Saúde (LILACS) e Scientific Electronic Library Online (SciELO) a partir de 23 artigos publicados no último ano. RESULTADOS: Uma minoria das gestantes foi assintomática, a maior parte desenvolveu algum tipo de sintoma. A sintomatologia apresentada foi diversa, sendo febre e tosse as mais relatadas, enquanto tontura foi o sintoma com menor prevalência. Observou-se que o número de gestantes com quadro grave não foi prevalente. Houve notavelmente um aumento do número de cesarianas por indicação obstétrica e da prevalência de Trabalho de Parto Prematuro (TPP). As alterações laboratoriais prevalentes foram linfopenia e aumento da proteína C reativa. CONCLUSÃO: Observa-se a necessidade de atenção e cuidado às gestantes infectadas pelo COVID-19, tendo em vista a diversidade de alterações e desfechos. Além disso, é importante o desenvolvimento de um olhar aprimorado pela equipe de saúde, sobretudo àquelas com maior possibilidade de agravamento do quadro

The number of tree species on Earth

One of the most fundamental questions in ecology is how many species inhabit the Earth. However, due to massive logistical and financial challenges and taxonomic difficulties connected to the species concept definition, the global numbers of species, including those of important and well-studied life forms such as trees, still remain largely unknown. Here, based on global groundsourced data, we estimate the total tree species richness at global, continental, and biome levels. Our results indicate that there are 73,000 tree species globally, among which ∼9,000 tree species are yet to be discovered. Roughly 40% of undiscovered tree species are in South America. Moreover, almost one-third of all tree species to be discovered may be rare, with very low populations and limited spatial distribution (likely in remote tropical lowlands and mountains). These findings highlight the vulnerability of global forest biodiversity to anthropogenic changes in land use and climate, which disproportionately threaten rare species and thus, global tree richness

The number of tree species on Earth.

One of the most fundamental questions in ecology is how many species inhabit the Earth. However, due to massive logistical and financial challenges and taxonomic difficulties connected to the species concept definition, the global numbers of species, including those of important and well-studied life forms such as trees, still remain largely unknown. Here, based on global ground-sourced data, we estimate the total tree species richness at global, continental, and biome levels. Our results indicate that there are ∼73,000 tree species globally, among which ∼9,000 tree species are yet to be discovered. Roughly 40% of undiscovered tree species are in South America. Moreover, almost one-third of all tree species to be discovered may be rare, with very low populations and limited spatial distribution (likely in remote tropical lowlands and mountains). These findings highlight the vulnerability of global forest biodiversity to anthropogenic changes in land use and climate, which disproportionately threaten rare species and thus, global tree richness

The number of tree species on Earth.

One of the most fundamental questions in ecology is how many species inhabit the Earth. However, due to massive logistical and financial challenges and taxonomic difficulties connected to the species concept definition, the global numbers of species, including those of important and well-studied life forms such as trees, still remain largely unknown. Here, based on global ground-sourced data, we estimate the total tree species richness at global, continental, and biome levels. Our results indicate that there are ∼73,000 tree species globally, among which ∼9,000 tree species are yet to be discovered. Roughly 40% of undiscovered tree species are in South America. Moreover, almost one-third of all tree species to be discovered may be rare, with very low populations and limited spatial distribution (likely in remote tropical lowlands and mountains). These findings highlight the vulnerability of global forest biodiversity to anthropogenic changes in land use and climate, which disproportionately threaten rare species and thus, global tree richness

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data