1,654 research outputs found

    Narrow band amplification of light carrying orbital angular momentum

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    We report on the amplification of an optical vortex beam carrying orbital angular momentum via induced narrow Raman gain in an ensemble of cold cesium atoms. A 20\% single-pass Raman gain of a weak vortex signal field is observed with a spectral width of order of 1 MHz, much smaller than the natural width, demonstrating that the amplification process preserves the phase structure of the vortex beam. The gain is observed in the degenerated two-level system associated with the hyperfine transition 6S1/2(F=3)↔6P3/2(F′=2)6S_{1/2}(F=3)\leftrightarrow 6P_{3/2}(F^{\prime}=2) of cesium. Our experimental observations are explained with a simple theoretical model based on a three-level Λ\Lambda system interacting coherently with the weak Laguerre-Gauss field and a strong coupling field, including an incoherent pumping rate between the two degenerate ground-states.Comment: 9 pages, 4 figure

    Cruzamentos em dialelo de genótipos de arroz irrigado de base genética ampla.

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    Este trabalho visa dar continuidade aos estudos conduzidos com a Coleção Nuclear de Arroz da Embrapa (CNAE). O ensaio foi um dialelo, envolvendo dezesseis genitores, que compõem uma Mine amostra da CNAE. Buscou-se a distância genética entre os genitores e a correlação com a heterose obtida nas variáveis medidas nos híbridos. Além da busca de combinações promissoras para o programa de melhoramento, visou-se também o entendimento do comportamento de cruzamentos de genótipos de base genética ampla. Procurou-se também encontrar combinações que sirva para estudos, nas diversas áreas acopladas ao melhoramento

    The use of information and communication technologies in perinatal depression screening: A systematic review

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    Perinatal mental illness refers to psychiatric disorders that exist during pregnancy and up to 1 year after childbirth. The aim of this systematic review was to discuss the use of Information and Communication Technologies (ICTs) on perinatal depression (PeD) screening in the past three decades. Published articles were searched between 1990 and 2018, both in English and Spanish. In the search, we used different keywords, such as "pregnancy, " "depression, " or "technology" in ScienceDirect, PubMed-NCBI, and Web of Science. We found 10 articles that combined the use of ICTs and a focus on PeD screening. Studied periods included pregnancy (n = 2) and postpartum (n = 8). The telephone was the most commonly used communication method (n = 5), followed by the Internet (n = 4). One investigation used both, the telephone and the Internet. The Edinburgh Postnatal Depression Scale was the most frequently used screening measure (n = 8). The proportion of depressed perinatal women varied across studies depending on the pregnancy status and the cutoff values used, showing a very broad range between 5.8 and 51.9 percent. Despite the increasing popularity of ICTs in health settings, their use in perinatal mental health screening is still rare. Overall, encouraging findings have been reported when using ICTs for screening of PeD, such as eliminating the need to travel to the health center to conduct the screening and allowing for a wider dissemination. However, more research is needed to support their inclusion in perinatal care

    Maturidade fisiolĂłgica de sementes do hĂ­brido simples BR 201 fĂŞmea de milho (Zea mays L.) produzidas no inverno.

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    Sementes de milho hibrido simples BR 201 femea produzidas no periodo de inverno, foram colhidas em intervalos de sete dias, a partir do 30 dia apos a floracao ate o 128 com o objetivo de se estudar a maturidade fisiologica. as sementes foram analisadas quanto ao grau de umidade, materia seca, ocorrencia de camada preta, germinacao e vigor. Nas condicoes em que o trabalho foi realizado, os resultados permitiram chegar as seguintes conclusoes: a maturidade fisiologica das sementes, com base no acumulo de materia seca, ocorreu aos 58 dias apos a floracao- sementes de alta qualidade fisiologica podem ser obtidas com colheitas antecipadas em relacao ao maximo acumulo de materia seca, implicando em um intervalo otimo para colheita em ate 14 dias antes do ponto de maturidade fisiologica: a producao de sementes no inverno, permite a obtencao de sementes de alta qualidade, em menor espaco de tempo que no cultivo em epoca normal
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