9,013 research outputs found

    Monitoramento da susceptibilidade de Euschistus heros (Hemiptera: Pentatomidae) aos inseticidas beta-ciflutrina e imidacloprido em Mato Grosso

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    Euschistus heros é um praga polifaga importante nos sistemas produtivos de grãos e fibras mato-grossenses, pois é a principal espécie de percevejo que ataca a cultura da soja, além de atacar o milho no início da emergência das plantas e as maças do algodoeiro. Portanto, sua permanência no campo é prolongada devido à extensa janela de cultivo no Estado. Consequentemente, o período de exposição aos inseticidas é potencializado quando comparado a sistemas produtivos com uma única safra que hospede a praga. Diante disso, objetivou-se monitorar os níveis de susceptibilidade do percevejo aos inseticidas imidacloprido e beta-ciflutrina. Para avaliar o nível de susceptibilidade das populações de campo, determinou-se uma dose diagnóstica em uma população susceptível de E. heros ao avaliar a mortalidade dos insetos em concentrações crescentes dos dois inseticidas. Desta forma, calculou-se a Concentração Letal para 95% dos indivíduos susceptíveis - CL95 , através da análise de probit. As doses diagnósticas estimadas foram de 3µl/ml (beta-ciflutrina/água) e 0,5µl/ml (imidacloprido/água). Os produtos comerciais utilizados continham as concentrações de 50 g/L de ingrediente ativo para beta-ciflutrina e 200 g/L de ingrediente ativo para imidacloprido. As populações de campo foram coletadas em soja na safra 2013/14 nos municípios de Rondonópolis, Nova Mutum e Sinop. Para a molécula imidacloprido, todas as populações tiveram uma mortalidade parecida com a população susceptível, porém para a molécula beta-ciflutrina a população de Rondonópolis diferenciou significativamente da população susceptível. Entretanto, falhas de controle em campo não são d iagnosticadas, pois os inseticidas registrados para o controle da praga que contém esses ingredientes ativos são uma mixtura de beta-ciflutrina com imidacloprido, assim promovendo efetivo controle devido ao imidacloprido

    Rossby Wave Instability and three-dimensional vortices in accretion disks

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    Context. The formation of vortices in accretion disks is of high interest in various astrophysical contexts, in particular for planet formation or in the disks of compact objects. But despite numerous attempts it has thus far not been possible to produce strong vortices in fully three-dimensional simulations of disks. Aims. The aim of this paper is to present the first 3D simulation of a strong vortex, established across the vertically stratified structure of a disk by the Rossby Wave Instability. Methods. Using the Versatile Advection Code (VAC), we set up a fully 3D cylindrical stratified disk potentially prone to the Rossby Wave Instability. Results. The simulation confirms the basic expectations obtained from previous 2D analytic and numerical works. The simulation exhibits a strong vortex that grows rapidly and saturates at a finite amplitude. On the other hand the third dimension shows unexpected additional behaviours that could be of strong importance in the astrophysical roles that such vortices can play.Comment: Accepted by Astronomy and Astrophysic

    Produção e composição do leite de ovelhas Santa Inês e mestiças Lacaune e Santa Inês e desenvolvimento de seus cordeiros.

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    Na ovinocultura, a raça Santa Inês, amplamente explorada no território brasileiro, possui índices de produção compatíveis com sistemas europeus de exploração leiteira (Susin et al., 2005), e o bom desempenho de animais na fase de cria está diretamente relacionado com a produção de leite das mães (Peeters et al., 1992). A raça Lacaune tem sua origem atrelada à produção de animais de boa carcaça em diversas regiões da França e passou por um programa de melhoramento genético que resultou em aumento da produção de leite e melhora da composição da carcaça dos cordeiros destinados ao abate (Barillet et al., 2001). O presente trabalho teve o objetivo de avaliar a produção e a composição do leite de três genótipos de ovelhas Santa Inês, ½ Lacaune x ½ Santa Inês e ¾ Lacaune x ¼ Santa Inês ? e o desenvolvimento de seus cordeiros durante os quatro primeiros meses de lactação

    In situ degradability of elephant grass ensiled with acerola by-product.

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    This study evaluated the inclusion of increasing contents (0; 35; 70; 105 and 140 g kg-1) of dried acerola fruit (Malpighia glabra, Linn.) by-product (DABP) in the ensilage of elephant grass (Pennisetum purpureum, Schum.) considering the in situ degradability of dry matter (DM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF) and hemicellulose. Plastic drums with 210 L capacity were used as experimental silos. After 45 days of ensiling, silos were opened and silage samples were collected for the degradability trial and laboratory analysis. For the in situ degradability trial, was used one rumen-fistulated adult male cattle. The five by-product inclusion contents were tested in three replicates, with five incubation times, in a randomized complete split-plot design in which the contents of DABP were the treatments (plots), the different silos were the replicates and the incubation times were the sub-plots. Longer incubation times significantly increased (P < 0.05) the disappearance rates of DM, CP, NDF, ADF and hemicellulose. The effective degradability of the DM, NDF and hemicellulose was higher in the silages with 35 g kg-1 of DABP in the rumen passage rates of 0.02; 0.05 and 0.08 h-1. Dried acerola fruit by-product can be added to elephant grass ensiling up to 35 g kg-1 without reducing the effective degradability of nutrients

    Nanomaterials for Advancing the Health Immunosensor

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    Nanotechnology has exerted a significant impact in the development of biosensors allowing more sensible analytical methods. In health applications, the main challenge of the immunoassay is to reach the suitable limit of detection, recognizing different analytes in complex samples like whole blood, serum, urine, and other biological fluids. Different nanomaterials, including metallic, silica and magnetic nanoparticles, quantum dots, carbon nanotubes, and graphene, have been applied, mainly to improve charge electron transfer, catalytic activity, amount of immobilized biomolecules, low-background current, signal-to-noise ratio that consequently increase the sensitivity of immunosensors. Given the great impact of nanotechnology, this chapter intends to discuss new aspects of nanomaterials relating to immunosensor advancement

    Land cover evolution of small farms: the Transamazon highway.

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    The dynamics of land use change in both the mid and long-run were determined for a sample of 132 small farmers located along the Transamazon Highway. On average, four deforestation events occurred after arrival on the property. The average area of deforested land was 10 hectares for each event, totaling 40 of the 50 hectares allowed by law for a typical size plot of 100 hectares. It was observed that small farmers along the Transamazon Highway employ diversified systems of land use including annual crops, perennials and cattle; these show a temporal sequence in accord with household domestic cycles. These results suggest that pasture conversion in Amazon by small farmers is due to domestic dynamics cycle in addition to others variables

    Tracing kinematical and physical asymmetries in the jet from DG Tau B

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    Stellar jets can be highly asymmetric and have multiple velocity components. To clarify the origin of jet asymmetries and constrain their launch mechanism we study the physical and kinematical structure of the flow emitted by DG Tau B. The analysis of deep spectra taken at the KECK telescope allows us to infer the physical properties (the electron and total density, ne and nh, the ionisation fraction, xe, and the temperature, te) and the spatial distribution of the velocity components in the two jet lobes. The presence of dust grains in the jet is investigated by estimating the gas-phase abundance of calcium with respect to its solar value. At the base of the jet the lines are broad (~100 km/s) and up to three velocity components are detected. At 5" from the source, however, only the denser and more excited high velocity components survive and the lines are narrower (~10-30 km/s). The jet is strongly asymmetric both in velocity and in its physical structure. The red lobe, slower (~140 km/s) and more collimated, presents low ionisation fractions (xe~0.1-0.4) and temperatures (te<5e3 K), while the total density is up to ~2.5e4 ccm. The blue lobe, faster (~-320 km/s) and less collimated, is also less dense (nh~1e4 ccm) but highly excited (te up to ~5e4 K and xe up to 0.9). The estimated mass loss rate is similar in the two lobes (~6-8e-9 Msol/yr), suggesting that the ejection power is comparable on the two sides of the system, as expected from a magneto-centrifugal ejection mechanism, and that the observed asymmetries are due to different mass load and propagation properties in an inhomogeneous environment. Calcium is strongly depleted, indicating that the jet contains dust grains and, therefore, should originate from a region of the disk extending beyond the dust sublimation radius. The depletion is lower for higher velocities, consistent with dust destruction by shocks.Comment: 14 pages, 9 figures, accepted by A&
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