Nonintegrable Interaction of Ion-Acoustic and Electromagnetic Waves in a Plasma

In this paper we re-examine the one-dimensional interaction of electromagnetic and ion acoustic waves in a plasma. Our model is similar to one solved by Rao et al. (Phys. Fluids, vol. 26, 2488 (1983)) under a number of analytical approximations. Here we perform a numerical investigation to examine the stability of the model. We find that for slightly over dense plasmas, the propagation of stable solitary modes can occur in an adiabatic regime where the ion acoustic electric field potential is enslaved to the electromagnetic field of a laser. But if the laser intensity or plasma density increases or the laser frequency decreases, the adiabatic regime loses stability via a transition to chaos. New asymptotic states are attained when the adiabatic regime no longer exists. In these new states, the plasma becomes rarefied, and the laser field tends to behave like a vacuum field.Comment: 19 pages, REVTeX, 6 ps figures, accepted for publication in Phys. Rev.

Atividade da acetolactato sintase de plantas de milho e de amendoim-bravo (Euphorbia heterophylla) resistentes e suscetíveis ao imazaquin

O amendoim-bravo, (Euphorbia heterophylla) é uma importante planta daninha em mais de 56 países, inclusive no Brasil, onde tem sido relatado o aparecimento de populações resistentes aos herbicidas inibidores da acetolactato sintase (ALS). O objetivo do trabalho foi avaliar o efeito do herbicida imazaquin na atividade da ALS extraída das plantas de milho e amendoim-bravo, resistentes e suscetíveis ao produto. Sementes de dois genótipos de milho e vários biótipos de amendoim-bravo provenientes de diferentes regiões agrícolas brasileiras foram cultivadas em casa de vegetação por 21 dias. A atividade da ALS extraída das folhas das plantas foi determinada na presença de doses de imazaquin. A etapa de purificação da enzima foi substituída por uma centrifugação de 2.800 rpm por dois minutos. Equações de regressão linear para absorbância em função do log da concentração de imazaquin foram ajustadas para cada população, visando obtenção do I50. A dose de imazaquin necessária para inibir 50% da atividade da ALS (I50) na variedade de milho Pioneer 3162 IR (I50 260 µM) foi 4.333 vezes maior que a dose requerida pela BRS 473 (0,06 µM), a qual é suscetível ao imazaquin. Os biótipos de amendoim-bravo provenientes do Rio Grande do Sul apresentaram valores de I50 de 1.961,3 e 13,8 mM para os biótipos resistentes e suscetíveis, respectivamente. Os biótipos provenientes de Cafelândia e Maringá (PR) e Viçosa (MG) apresentaram valores de I50 maiores que 5.000 mM para os biótipos resistentes e maiores que 1.000 mM para os suscetíveis. O amendoim-bravo coletado na Embrapa Milho e Sorgo, em área que nunca foi tratada com herbicidas inibidores da ALS, apresentou I50 de 12,2 mM. Conclui-se que a medida in vitro da atividade da ALS é um método sensível para determinação da presença de biótipos resistentes à ação do herbicida imazaquin. A etapa de purificação da ALS pode ser substituída por um método que envolve uma rápida centrifugação.Wild poinsettia (Euphorbia heterophylla) is an important weed in more than 56 countries, including Brazil, where resistant biotypes to ALS inhibiting herbicides have been reported in soybean crops. The objectives of this research were to evaluate the effect of imazaquin on the activity of the acetolactate synthase (ALS), extracted from two corn varieties and several biotypes of E. heterophylla from Brazilian agricultural areas. Plants were grown under greenhouse conditions for 21 days. The ALS activity of wild poinsettia has shown resistance to imazaquin herbicide in soybean crops. In vitro acetolactate synthase (ALS) activity of imazaquin-resistant wild poinsettia collected in different soybean production areas from Brazil and the two corn populations was compared to that of imazaquin-sensitive populations. The activity of the ALS extracted from the leaves was measured with different imazaquin rates. The ALS purification process was substituted by centrifugation at 2800 rpm during two minutes. Linear regression equation for specific light length absorbance as a function of the log concentration of imazaquin was built to obtain I50 value (50% inhibition of the enzyme activity). The I50 values of Pioneer 3162 IR (I50 260 µM) corn genotype were 4,333 times higher than BRS 473-sensitive (0,06 µM). The wild poinsettia biotypes from the state of Rio Grande do Sul had I50 values of 1,961.3 µM and 13.8 µM for the resistant and sensitive biotypes, respectively. The resistant populations from Cafelândia, Maringá (PR) and Viçosa (MG) had I50 values higher than 5,000 µM, while the sensitive population had values higher than 1,000 µM. The I50 value for the wild poinsettia population collected from fields that had never been sprayed with imazaquin was of 12.2 µM. Therefore, the in vitro ALS activity was a sensitive method to detect wild poinsettia-resistant imazaquin and ALS purification can be substituted for a method involving a quick centrifugation process

ISOLAMENTO DO Ureaplasma diversum EM MUCO VULVOVAGINAL DE VACAS LEITEIRAS REPETIDORAS DE ESTRO NO ESTADO DE ALAGOAS BRASIL

Ureaplasma diversum is an opportunistic bacteria of the bovine genital tract and an important agent in granular vulvovaginitis, abortion, low fertility herd rate and respiratory problems in calves. The aim of this work was to study the relationship between positive cultures for Ureaplasma diversum and the extension and severity of the lesions in the vaginal mucosa of repeat breeders dairy cows in Alagoas State, Brazil. Visual evaluation were performed in 93 cows to evaluate the vaginal lesion score (VLS), classified according the lesion severity and extension (0 to 4, with 0= no lesions, 4= severe inflammation and local necrosis). The VLS 1 was the most frequent (51,61%). VLS 0 was present in 17,2% of the females, while 29,03% and 2,16% showed VLS 2 and 3, respectively. None of the cows showed VLS 4. Vaginal swab samples were obtained from 24 females (25%). Of them, 41,7% were positive for U. diversum. The presence of U. diversum was associated positively to VLS, especially to those cows showing vaginal lesion score 1. The present results indicated that Ureaplasma diversum should be considered responsible for low reproductive efficiency, carrying out to repeat breeding, probably because of embryo mortality.O Ureaplasma diversum é um patógeno oportunista do trato genital dos bovinos que causa surtos de vulvovaginite granular, seguidos de abortamento e redução da eficiência reprodutiva do rebanho. O presente estudo foi desenvolvido com o objetivo de avaliar a relação entre a extensão e a gravidade das lesões de vulvovaginite observadas com o isolamento de Ureaplasma diversum em amostras colhidas diretamente da mucosa vulvovaginal, em fêmeas de aptidão leiteira repetidoras de estro no estado de Alagoas, Brasil. A avaliação da extensão e severidade das lesões foi feita em 93 vacas com histórico de repetição regular de estro após três ou mais inseminações artificiais, seguindo-se a seguinte metodologia de classificação: graus de 0 a 4, sendo 0=sem lesões; 4=lesões severas, com hemorragia e necrose. Dos 93 animais avaliados, 17,2% apresentavam lesão grau 0; 51,61% grau 1; 29,03% grau 2; 2,16% grau 3 e nenhum animal mostrou lesão de grau 4. Foi colhido muco vulvovaginal de 24 vacas, escolhidas aleatoriamente, para processamento bacteriológico, encontrando-se 41,67% das amostras positivas para Ureaplasma diversum. O isolamento do agente esteve positivamente relacionado à presença de lesões na mucosa vulvovaginal, especialmente àquelas de grau 1. Os resultados deste estudo indicam que o Ureaplasma diversum deve ser considerado como agente responsável por queda na eficiência reprodutiva, promovendo retorno ao estro, provavelmente em conseqüência de mortalidade embrionária

INFUSÃO UTERINA COM BIGUANIDA POLIMÉRICA SOBRE A COLONIZAÇÃO BACTERIANA DO ÚTERO DE VACAS COM INFECÇÃO PUERPERAL APÓS RETENÇÃO DE ENVOLTÓRIOS FETAIS

This study was carried out with the aim to verify the utilization viability of polymeric biguanide solutions for the topic treatment of puerperal uterine infections in bovine females after premature parturition. Twenty Girolando cows of a dairy farm, with placenta retention and metritis were randomly distributed in two groups. Group 1, constituted of cows that received three uterine infusions of a polymeric biguanide solution, and Group 2, with animals that were not submitted to any treatment. There were taken uterine content samples at the first, third and fifth post partum weeks for bacteriological cultures, that means, before the first infusion, 14 and 28 days after treatment. The founds of bacteriological cultures in the two groups demonstrated that the solution of polymeric biguanide was not effective to reduce uterine bacteriological colonization in cows with post partum infections.Com o objetivo de estudar a viabilidade da utilização de biguanida polimérica, no tratamento tópico de infecções puerperais em fêmeas bovinas após o parto prematuro, 20 fêmeas Girolando pertencentes a um sistema de produção leiteira, que apresentaram retenção de envoltórios fetais e conseqüentemente endometrite puerperal, foram distribuídas aleatoriamente em dois grupos. O Grupo I, foi constituído de animais que receberam três infusões uterinas de biguanida polimérica; e o Grupo 2, animais não tratados. Foram realizadas colheitas de conteúdo uterino na primeira, terceira e quinta semanas pós-parto para realização de cultivos bacteriológicos, ou seja, antes da infusão, aos 14 e 28 dias após tratamento medicamentoso. O resultado dos cultivos bacteriológicos nos dois grupos demonstrou que a utilização da biguanida polimérica não reduziu a colonização bacteriana no útero dos animais tratados, em comparação àqueles não tratados

Alpha-decay branching ratios of near-threshold states in 19Ne and the astrophysical rate of 15O(alpha,gamma)19Ne

The 15O(alpha,gamma)19Ne reaction is one of two routes for breakout from the hot CNO cycles into the rp process in accreting neutron stars. Its astrophysical rate depends critically on the decay properties of excited states in 19Ne lying just above the 15O + alpha threshold. We have measured the alpha-decay branching ratios for these states using the p(21Ne,t)19Ne reaction at 43 MeV/u. Combining our measurements with previous determinations of the radiative widths of these states, we conclude that no significant breakout from the hot CNO cycle into the rp process in novae is possible via 15O(alpha,gamma)19Ne, assuming current models accurately represent their temperature and density conditions

Global agricultural intensification during climate change: A role for genomics

Summary: Agriculture is now facing the 'perfect storm' of climate change, increasing costs of fertilizer and rising food demands from a larger and wealthier human population. These factors point to a global food deficit unless the efficiency and resilience of crop production is increased. The intensification of agriculture has focused on improving production under optimized conditions, with significant agronomic inputs. Furthermore, the intensive cultivation of a limited number of crops has drastically narrowed the number of plant species humans rely on. A new agricultural paradigm is required, reducing dependence on high inputs and increasing crop diversity, yield stability and environmental resilience. Genomics offers unprecedented opportunities to increase crop yield, quality and stability of production through advanced breeding strategies, enhancing the resilience of major crops to climate variability, and increasing the productivity and range of minor crops to diversify the food supply. Here we review the state of the art of genomic-assisted breeding for the most important staples that feed the world, and how to use and adapt such genomic tools to accelerate development of both major and minor crops with desired traits that enhance adaptation to, or mitigate the effects of climate change. &gt

The unexpected resurgence of Weyl geometry in late 20-th century physics

Weyl's original scale geometry of 1918 ("purely infinitesimal geometry") was withdrawn by its author from physical theorizing in the early 1920s. It had a comeback in the last third of the 20th century in different contexts: scalar tensor theories of gravity, foundations of gravity, foundations of quantum mechanics, elementary particle physics, and cosmology. It seems that Weyl geometry continues to offer an open research potential for the foundations of physics even after the turn to the new millennium.Comment: Completely rewritten conference paper 'Beyond Einstein', Mainz Sep 2008. Preprint ELHC (Epistemology of the LHC) 2017-02, 92 pages, 1 figur