Spectral Asymptotic Properties of Semiregular Non-commutative Harmonic Oscillators.

We study here the spectral Weyl asymptotics for a semiregular system, extending to the vector-valued case results of Helffer and Robert, and more recently of Doll, Gannot and Wunsch. The class of systems considered here contains the important example of the Jaynes–Cummings system that describes light-matter interaction

A substituição de capins em pastagens tropicais perenes por meio da técnica da sobressemeadura a lanço.

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Estabelecimento de pastos dos capins 'Tifton 85' e Jiggs com dois tipos de mudas e preparos de solo, em monocultivo ou integração lavoura-pecuária.

Resumo: Plantas forrageiras do gênero Cynodon são usadas em diversos sistemas de produção de carne e leite, mas a propagação vegetativa desses capins apresenta desafios para o estabelecimento. O objetivo deste estudo foi descrever e explicar alterações no estabelecimento de pastos dos capins 'Tifton 85' (Cynodon spp.) e Jiggs [Cynodon dactylon (L.) Pers.] em resposta a dois tipos de mudas (muda enraizada tipo plug ou muda de parte aérea), dois tipos de preparo do solo (plantio direto ou preparo convencional), em monocultivo ou na integração lavoura-pecuária (ILP) com milho de segunda safra. O período experimental foi de 2 de janeiro a 4 de julho de 2023. O delineamento experimental foi em blocos completos casualizados, com arranjo fatorial 2 × 2 × 2, com quatro repetições. O preparo de solo não foi casualizado por questões logísticas e os dados foram analisados por modelos mistos com os preparos de solo em experimentos combinados. As densidades de mudas plantadas foram de 1 plug m-2 e 2 Mg de parte aérea ha-1. Os pastos foram considerados estabelecidos quando 95% da superfície do solo estava coberta pelo capim. No monocultivo, o capim Jiggs, a parte aérea e o preparo convencional do solo estabeleceram em menos tempo que o Tifton 85, a muda plug e o plantio direto, com diferenças de 8, 6 e 10 dias, respectivamente. Na ILP, o estabelecimento dos capins não foi atingido. No monocultivo, o acúmulo de forragem (AF) no ano, com preparo convencional, foi de 7800 kg MS ha-1 e no plantio direto foi de 6510 kg MS ha-1. Com a muda de parte aérea o AF foi de 7440 kg MS ha-1, enquanto com a muda plug foi de 6870 kg MS ha-1. A altura do dossel ao final do estabelecimento foi de 30 e 19 cm para Tifton 85 e Jiggs, respectivamente e de 22 e 27 cm para plug e parte aérea, respectivamente. O plantio direto e a muda plug são tecnologias que podem ser usadas na formação de pastos de Tifton 85 e Jiggs em monocultivo, porém demoram alguns dias a mais para completar o estabelecimento e são menos produtivas no ano de plantio, comparativamente às técnicas convencionais (preparo convencional do solo e muda de parte aérea). O efeito combinado de sombreamento, competição com plantas invasoras e doenças foliares podem ter impedido o completo estabelecimento de Tifton 85 e Jiggs na ILP com milho segunda safra no ano do plantio, motivo pelo qual essa modalidade não é adequada para o plantio dos capins. | Abstract: Forage plants of the genus Cynodon are used in several beef and dairy production systems, but the vegetative propagation method of these grasses presents challenges for establishment. The objective of this study was to describe and explain changes in the establishment of pastures of Tifton 85 (Cynodon spp.) and Jiggs [Cynodon dactylon (L.) Pers.] grasses in response to two types of seedlings (plug seedling or seedling cut top ), two types of soil preparation (no-till or conventional tillage), in monoculture or crop-livestock integration (CLI) with second-crop corn. The experimental period was from January 2nd to July 4th, 2023. The experimental design was a randomized complete blocks, with a 2 × 2 × 2 factorial arrangement, with four replications. Soil preparation was not randomized for logistical reasons and data was analyzed using mixed models in combined experiments. The densities of seedlings planted were 1 plug seedling m-2 and 2 Mg tops ha-1. Pastures were considered established when 95% of the soil surface was covered by grass. In monoculture, Jiggs grass, the cut top and conventional tillage established in less time than Tifton 85, plug seedling and no-till, with differences of 8, 6 and 10 days, respectively. In CLI, grass establishment was not achieved. In monoculture, the herbage accumulation (HA) for the year with conventional tillage was 7800 kg DM ha-1 and in no-till it was 6510 kg DM ha-1. With the cut top, the HA was 7440 kg DM ha-1, while with the plug seedling it was 6870 kg DM ha-1. Canopy height at the end of establishment was 30 and 19 cm for Tifton 85 and Jiggs, respectively, and 22 and 27 cm for plug and cut top, respectively. No-till and plug seeding are technologies that can be used in the establishment of Tifton 85 and Jiggs pastures in monoculture, but they take a few days longer to complete establishment and are less productive in the planting year, compared to conventional techniques (conventional tillage and cut top). The combined effect of shade, competition with invasive plants, and foliar diseases may have prevented the full establishment of Tifton 85 and Jiggs in CLI with second-crop corn in the planting year, which is why this modalities is not suitable for planting these grasses.Orientador: Carlos Guilherme Silveira Pedreira, USP-ESAL

Manual de representação do sistema GECAMPE.

O Sistema de Gerenciamento de Campos Experimentais – Gecampe encontra-se na fase piloto de desenvolvimento. Sua interface computacional vem sendo utilizada desde janeiro de 2010, data em que foi implantada a primeira versão da ficha de campo, ferramenta de coleta diária dos dados. Desde então, as diversas atividades realizadas para o aprimoramento do sistema vêm sendo validadas junto aos colaboradores da Embrapa Pecuária Sudeste.bitstream/item/34038/1/Documentos99.pd

Correlation between mechanical properties and processing conditions in rubber-toughened wood polymer composites

The use of wood fibers is a deeply investigated topic in current scientific research and one of their most common applications is as filler for thermoplastic polymers. The resulting material is a biocomposite, known as a Wood Polymer Composite (WPC). For increasing the sustainability and reducing the cost, it is convenient to increase the wood fiber content as much as possible, so that the polymeric fraction within the composite is thereby reduced. On the other hand, this is often thwarted by a sharp decrease in toughness and processability-a disadvantage that could be overcome by compounding the material with a toughening agent. This work deals with the mechanical properties in tension and impact of polypropylene filled with 50 wt.% wood flour, toughened with different amounts (0%, 10%, and 20%) of a polypropylene-based thermoplastic vulcanizate (TPV). Such properties are also investigated as a function of extrusion processing variables, such as the feeding mode (i.e., starve vs. flood feeding) and screw speed. It is found that the mechanical properties do depend on the processing conditions: the best properties are obtained either in starve feeding conditions, or in flood feeding conditions, but at a low screw speed. The toughening effect of TPV is significant when its content reaches 20 wt.%. For this percentage, the processing conditions are less relevant in governing the final properties of the composites in terms of the stiffness and strength

Genotoxic activity of the Fumonisin B1 mycotoxin in cultures of bovine lymphocytes

The fumonisins, produced by fungi that infest foodstuffs, in particular corn, are responsible for a series of illnesses and toxicosis in various species of animals, including humans. There is still not detailed information about the genotoxic and mutagenic activity of Fumonisin B1 (FB1), but it is clear that it interferes with growth control, differentiation and cellu- lar apoptosis. The purpose of this study was to assess the genotoxic potential of Fumonisin B1 using in vitrocultures of bovine lymphocytes, through the calculation of the ‘mitotic index’ (MI), the frequency of ‘sister chromatid exchange’ (SCE) and the ‘micronucleus test’ (MN). The bovine lymphocytes were exposed to different concentrations of FB1 (25, 50 and 100 µM) in order to find out which amount is sufficient to cause a reduction in the mitotic potential of the cells, the onset of MN and a higher frequency of SCE. The results obtained show a considerable reduction in the ‘mitotic index’ with a FB1 concentration of 50 µM, an increase in the frequency of MN with a concentration of 50 µM and a significant increase in the SCE with a concentration of 100 µM. In the light of the information we have obtained, compared with that of other Authors, we feel that the genotoxic poten- tial of FB1 has been underestimated until now and should, therefore, be reconsidered