33 research outputs found

    Corantes comumente empregados na citogenética vegetal.

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    O emprego dos corantes, na citogenética vegetal, data de muitos anos, uma vez que as pesquisas nas áreas da citologia e histologia vêm sendo desenvolvidas constantemente desde os primeiros estudos celulares no século XIX. Inicialmente, eram extraídos de fontes vegetais ou animais, sendo atualmente produzidos sinteticamente em escala comercial. Os corantes são classificados em não fluorescentes e fluorescentes, conforme suas propriedades químicas e a escolha de uso é de acordo com o tipo de estrutura celular ou grupo celular a ser analisado. A diversidade de tipos e compostos químicos existentes nos diferentes corantes proporciona sua aplicação em estudos avançados na citogenética clássica e molecular. Uma revisão de suas propriedades químicas e emprego é apresentada para os corantes não fluorescentes orceína, hematoxilina, Giemsa, carmin; e para os fluorescentes 4',6-diamidino-2-fenilindol (DAPI), cromomicina A (CMA), fluoresceína e rodamina

    Determination of the number of J/ψ events with inclusive J/ψ decays

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    A measurement of the number of J/ψ events collected with the BESIII detector in 2009 and 2012 is performed using inclusive decays of the J/ψ. The number of J/ψ events taken in 2009 is recalculated to be (223.7 ± 1.4) × 106, which is in good agreement with the previous measurement, but with significantly improved precision due to improvements in the BESIII software. The number of J/ψ events taken in 2012 is determined to be (1086.9 ± 6.0) × 106. In total, the number of J/ψ events collected with the BESIII detector is measured to be (1310.6 ± 7.0) × 106, where the uncertainty is dominated by systematic effects and the statistical uncertainty is negligible

    Measurement of the absolute branching fraction for Λc+→Λμ+νμ

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    We report the first measurement of the absolute branching fraction for Λc+→Λμ+νμ. This measurement is based on a sample of e+e− annihilation data produced at a center-of-mass energy s=4.6 GeV, collected with the BESIII detector at the BEPCII storage rings. The sample corresponds to an integrated luminosity of 567 pb−1. The branching fraction is determined to be B(Λc+→Λμ+νμ)=(3.49±0.46(stat)±0.27(syst))%. In addition, we calculate the ratio B(Λc+→Λμ+νμ)/B(Λc+→Λe+νe) to be 0.96±0.16(stat)±0.04(syst)

    Improved measurement of the absolute branching fraction of D+ → K0µ+νµ

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    By analyzing 2.93 fb-1 of data collected at √s = 3.773 GeV with the BESIII detector, we measure the absolute branching fraction B(D+ → K 0µ+νµ) = (8.72 ±0.07stat. ±0.18sys.) %, which is consistent with previous measurements within uncertainties but with significantly improved precision. Combining the Particle Data Group values of B(D0 → K-µ+νµ), B(D+ → K 0e+νe), and the lifetimes of the D0 and D+ mesons with the value of B(D+ → K 0µ+νµ) measured in this work, we determine the following ratios of partial widths: Γ(D0 → K-µ+νµ)/Γ(D+ → K 0µ+νµ) = 0.963 ± 0.044 and Γ(D+ → K 0µ+νµ)/Γ(D+ → K 0e+νe) = 0.988±0.033. mechanisms with better accuracy. In addition, the improved B(D+ → K 0µ+νµ) can also be used to precisely determine the form factor f K+ (0) and the quark mixing matrix element |Vcs| from D semileptonic decays. Previous measurements of B(D+ → K 0µ+νµ) come from MARKIII, FOCUS and BESII. In this paper, by analyzing 2.93 fb-1 of data collected at the centerof- mass energy of √s = 3.773 GeV by the BESIII detector, we determine the absolute branching fraction of D+ → K 0µ+νµ. Throughout the paper, charge conjugation is implied
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