60 research outputs found
Coherent π0 photoproduction on the deuteron up to 4 GeV
The differential cross section for 2H(γ,d)π0 has been measured at deuteron center-of-mass angles of 90° and 136°. This work reports the first data for this reaction above a photon energy of 1 GeV, and permits a test of the apparent constituent counting rule and reduced nuclear amplitude behavior as observed in elastic ed scattering. Measurements were performed up to a photon energy of 4.0 GeV, and are in good agreement with previous lower energy measurements. Overall, the data are inconsistent with both constituent-counting rule and reduced nuclear amplitude predictions
Base molecular para resistência a fluazifop-p-butyl em capim-camalote (rottboellia cochinchinensis) da Costa Rica
Rottboellia cochinchinensis is an annual grass weed species known as itchgrass, or
“caminadora” in America´s Spanish speaking countries, and has become a major and
troublesome weed in several crops. The application of fluazifop-P-butyl at recommended
rates (125 g a.i. ha-1) was observed to be failing to control itchgrass in a field in San José,
Upala county, Alajuela province, Costa Rica. Plants from the putative resistant R. cochinchinensis
population survived fluazifop-P-butyl when treated with 250 g a.i. ha-1 (2X label rate) at the
three- to four-leaf stage under greenhouse conditions. PCR amplification and sequencing of
partial carboxyl transferase domain (CT) of the acetyl-CoA carboxylase (ACCase) gene were
used to determine the molecular mechanism of resistance. A single non-synonymous point
mutation from TGG (susceptible plants) to TGC (putative resistant plants) that leads to a
Trp-2027-Cys substitution was found. This Trp-2027-Cys mutation is known to confer
resistance to all aryloxyphenoxyproprionate (APP) herbicides to which fluazifop-P-butyl
belongs. To the best of our knowledge, this is the first report of fluazifop-P-butyl resistance
and a mutation at position 2027 for a Costa Rican R. cochinchinensis population.Rottboellia cochinchinensis, espécie de planta daninha anual conhecida como capim-camalote,
ou “caminadora”, em países de língua espanhola das Américas, tornou-se uma planta daninha
significativa e problemática em diversas culturas. Observou-se que a aplicação de fluazifop-p-butyl
nas doses recomendadas (125 g i.a. ha-1) não conseguiu controlar capim-camalote em uma região em
San José, condado de Upala, província de Alajuela, Costa Rica. As plantas da população supostamente
resistente de R. cochinchinensis sobreviveram a fluazifop-p-butyl quando tratadas com 250 g i.a. ha-1
(2X a dose do rótulo) na fase de três a quatro folhas em condições de estufa. Amplificação e
sequenciamento de reação em cadeia da polimerase de domínio de transferase de ácido carboxílico
parcial (TC) do gene acetil-CoA carboxilase (ACCase) foram utilizados para determinar o mecanismo
molecular de resistência. Foi encontrada uma mutação de ponto não sinônimo individual de TGG
(plantas suscetíveis) para TGC (plantas supostamente resistentes) que conduz a uma substituição
de Trp-2027-Cys. Sabe-se que essa mutação de Trp-2027-Cys confere resistência a todos os
herbicidas ariloxifenoxipropionatos (AFP) a que fluazifop-p-butyl pertence. Pelo visto, este é o primeiro
relato de resistência a fluazifop-p-butyl de uma mutação na posição 2027 para uma população
costarriquenha de R. cochinchinensisWest Florida Research and Education Center, University of Florida/[]//United States of AmericaUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Estación Experimental Agrícola Fabio Baudrit Moreno (EEAFBM
Measurements of Deuteron Photodisintegration up to 4.0 GeV
The first measurements of the differential cross section for the d(γ,p)n reaction up to 4.0 GeV were performed at the Continuous Electron Beam Accelerator Facility (CEBAF) at Thomas Jefferson Laboratory. We report the cross sections at the proton center-of-mass angles of 36°, 52°, 69°, and 89°. These results are in reasonable agreement with previous measurements at lower energy. The 89° and 69° data show constituent-counting-rule behavior up to 4.0 GeV photon energy. The 52° and 36° data disagree with the counting-rule behavior. The quantum chromodynamics (QCD) model of nuclear reactions involving reduced amplitudes disagrees with the present data.U.S. Department of Energy, National Science Foundatio
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