20 research outputs found

    The Physics of the B Factories

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    Chemical control of morning glory as a function of water restriction levels

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    Among the herbicides recommended for the dry season and registered to sugarcane crop, amicarbazone, isoxaflutole and the association diuron + hexazinone + sulfomethuron-methyl can be highlighted. These are pre-emergence herbicides efficient against broad-leaved weeds. Morning glory causes large losses in infested sugarcane fields by bending the stalks and interfering in harvesting. In this study the effectiveness of pre-emergence herbicides for two species of morning glory (Ipomoea hederifolia and Ipomoea grandifolia) was evaluated. Treatments were arranged in completely randomized factorial design (4 x 7). There were four periods of water restriction (0, 30, 60 and 90 days), seven chemical treatments [diuron + hexazinone + sulfometuron-methyl (1387 + 391 + 33.35 g a.i. ha-1), diuron + hexazinone + sulfometuron-methyl (1507.5 + 425 + 36.25 g a.i. ha-1), diuron + hexazinone + sulfometuron-methyl (1658.25 + 467.5 + 39.87 g a.i. ha-1), diuron + hexazinone + sulfometuron­methyl (1809 + 510 + 43.5 g a.i. ha-1), amicarbazone (1190 g a.i. ha-1), amicarbazone + isoxaflutole (840 + 82.5 g a.i. ha-1)] and a control with no application. At 7, 14, 21 and 28 days after the restoration of moisture, control was visually evaluated. After the final evaluation, the dry mass of morning glories was measured. At 90 days of water restriction, diuron + hexazinone + sulfometuron-methyl was more effective to control I. hederifolia than the amicarbazone + isoxaflutole tank mixture. The four diuron + hexazinone + sulfometuron­methyl doses have reduced morning glory dry mass to zero; whereas treatments with amicarbazone have not. The most effective treatment for morning glory control was diuron + hexazinone + sulfometuron-methyl. This result may be due to a possible synergistic interaction.Entre os herbicidas recomendados para a época seca e registrados para a cultura da cana-de-açúcar estão amicarbazone, isoxaflutole e a associação diuron + hexazinona + sulfometuron­metil. Esses herbicidas apresentam ação em pré-emergência e atuam em plantas daninhas de folha larga. Cordas-de-viola provocam grandes perdas em canaviais infestados, causando tombamento da cana e interferindo nas operações de colheita. Neste estudo foi avaliada a eficácia de controle de herbicidas pré-emergentes em duas espécies de corda-de-viola (Ipomoea hederifolia e Ipomoea grandifolia). Os tratamentos foram dispostos em esquema fatorial 4 x 7. Foram quatro períodos de restrição hídrica (0, 30, 60 e 90 dias), sete tratamentos químicos [diuron + hexazinona + sulfometuron-metil (1.387 + 391 + 33,35 g i.a. ha-1), diuron + hexazinona + sulfometuron-metil (1.507,5 + 425 + 36,25 g i.a. ha-1), diuron + hexazinona + sulfometuron-metil (1.658,25 + 467,5 + 39,87 g i.a. ha-1), diuron + hexazinona + sulfometuron-metil (1.809 + 510 + 43,5 g i.a. ha-1), amicarbazone (1.190 g i.a. ha-1) e amicarbazone + isoxaflutole (840 + 82,5 g i.a. ha-1)] e um controle sem aplicação. Após 7, 14, 21 e 28 dias do restabelecimento da umidade, foram realizadas avaliações visuais de controle. Depois da última avaliação, foi determinada a massa seca das cordas-de-viola. Após 90 dias de restrição hídrica, diuron + hexazinona + sulfometuron-metil controlou I. hederifolia de forma mais eficaz que a mistura de amicarbazone + isoxaflutole. As quatro doses de diuron + hexazinona + sulfometuron-metil reduziram a massa seca das cordas-de-viola a zero, o que não aconteceu com os tratamentos com amicarbazone. O tratamento mais eficaz para o controle de corda-de-viola foi diuron + hexazinona + sulfometuron-metil em todas as doses estudadas; esse resultado pode se dever a possíveis relações de sinergismo entre esses produtos

    Mitomycin-C in corneal surface excimer laser ablation techniques: a report by the American Academy of Ophthalmology.

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    To review the published literature assessing the efficacy and safety of mitomycin-C (MMC) as an adjunctive treatment in corneal surface excimer laser ablation procedures. Literature searches of the PubMed and Cochrane Library databases were last conducted on August 19, 2014, without language or date limitations. The searches retrieved a total of 239 references. Of these, members of the Ophthalmic Technology Assessment Committee Refractive Management/Intervention Panel selected 26 articles that were considered to be of high or medium clinical relevance, and the panel methodologist rated each article according to the strength of evidence. Ten studies were rated as level I evidence, 5 studies were rated as level II evidence, and the remaining 11 studies were rated as level III evidence. The majority of the articles surveyed in this report support the role of MMC as an adjunctive treatment in surface ablation procedures. When MMC is applied in the appropriate concentration and confined to the central cornea, the incidence of post-surface ablation haze is decreased. Although a minority of studies that evaluated endothelial cell density (ECD) reported an MMC-related decrease in ECD, no clinical adverse outcomes were reported. Over the past 15 years, the use of MMC during surgery in surface ablation has become widespread. There is good evidence of the effectiveness of MMC when used intraoperatively as prophylaxis against haze in higher myopic ablations. Although there are reports of decreased endothelial counts after the administration of MMC during surgery, the clinical significance of this finding remains uncertain, because no adverse outcomes were reported with as much as 5 years of follow-up. Optimal dosage, effectiveness as prophylaxis in lower myopic and hyperopic ablations, and long-term safety, particularly in eyes with reduced corneal endothelial cell counts from prior intraocular surgery, have yet to be established

    Femtosecond lasers for LASIK flap creation: a report by the American Academy of Ophthalmology.

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    To review the published literature to assess the safety, efficacy, and predictability of femtosecond lasers for the creation of corneal flaps for LASIK; to assess the reported outcomes of LASIK when femtosecond lasers are used to create corneal flaps; and to compare the differences in outcomes between femtosecond lasers and mechanical microkeratomes. Literature searches of the PubMed and Cochrane Library databases were last conducted on October 12, 2011, without language or date limitations. The searches retrieved a total of 636 references. Of these, panel members selected 58 articles that they considered to be of high or medium clinical relevance, and the panel methodologist rated each article according to the strength of evidence. Four studies were rated as level I evidence, 14 studies were rated as level II evidence, and the remaining studies were rated as level III evidence. The majority of published studies evaluated a single laser platform. Flap reproducibility varied by device and the generation of the device. Standard deviations in flap thicknesses ranged from 4 to 18.4 μm. Visual acuities and complications reported with LASIK flaps created using femtosecond lasers are within Food and Drug Administration safety and efficacy limits. Of all complications, diffuse lamellar keratitis is the most common after surgery but is generally mild and self-limited. Corneal sensation was reported to normalize by 1 year after surgery. Unique complications of femtosecond lasers included transient light-sensitivity syndrome, rainbow glare, opaque bubble layer, epithelial breakthrough of gas bubbles, and gas bubbles within the anterior chamber. Available evidence (levels I and II) indicates that femtosecond lasers are efficacious devices for creating LASIK flaps, with accompanying good visual results. Overall, femtosecond lasers were found to be as good as or better than mechanical microkeratomes for creating LASIK flaps. There are unique complications that can occur with femtosecond lasers, and long-term follow-up is needed to evaluate the technology fully
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