921 research outputs found

    New approach for analysing dynamical processes on the surface of photospheric vortex tubes

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    The majority of studies on multi-scale vortex motions employ a two-dimensional geometry by using a variety of observational and numerical data. This approach limits the understanding the nature of physical processes responsible for vortex dynamics. Here we develop a new methodology to extract essential information from the boundary surface of vortex tubes. 3D high-resolution magnetoconvection MURaM numerical data has been used to analyse photospheric intergranular velocity vortices. The Lagrangian Averaged Vorticity Deviation (LAVD) technique was applied to define the centers of vortex structures and their boundary surfaces based on the advection of fluid elements. These surfaces were mapped onto a constructed envelope grid that allows the study of the key plasma parameters as functions of space and time. Quantities that help in understanding the dynamics of the plasma, e.g. Lorentz force, pressure force, plasma-β\beta were also determined. Our results suggest that, while density and pressure have a rather global behaviour, the other physical quantities undergo local changes, with their magnitude and orientation changing in space and time. At the surface, the mixing in the horizontal direction is not efficient, leading to appearance of localized regions with higher/colder temperatures. In addition, the analysis of the MHD Poynting flux confirms that the majority of the energy is directed in the horizontal direction. Our findings also indicate that the pressure and magnetic forces that drive the dynamics of the plasma on vortex surfaces are unbalanced and therefore the vortices do not rotate as a rigid body

    Opportunistic Maintenance Based on CUSUM Control Charts

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    The use of a Ship Maintenance Management System is fundamental for the good performance of equipments and the entire platform. Over the systematic maintenance, the opportunistic maintenance is a concept that aims to minimize outages and costs preventing undesirable failures. To implement this kind of maintenance statistical methodologies must be used. The Cumulative Sum charts have a very good performance applied to processes control in quality control. We proposed the use of Modified Cumulative Sum control charts to equipment maintenance.The data under study are observations of cooling water and oil temperatures from a diesel generator. In the first phase, we will apply traditional control charts, and, in the second phase, the Cumulative charts with a certain Average Run Length will be used. Then we will compare the results and extract conclusions, presenting measures for improvement.info:eu-repo/semantics/publishedVersio

    Control Charts Limits Flexibility Based on the Equipment Conditions

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    Condition Based Maintenance became an important development in industrial and transport equipment maintenance efforts. Many statistical methodologies have been applied in this area. These methodologies are usually applied off-line: after the data is collected. We propose an online, real-time condition monitoring system based on a modified control chart, applied to engine parameters. These charts should be flexible enough and its control limits should reflect the equipment state, the manufacturer specifications and onboard meteorological conditions. In this study we will develop a methodology to specify flexible chart control limits. The experimental equipment is a combined diesel or gas propulsion system. Two phases will be assumed. In phase 1 the equipment and historical data are analyzed, studying historical data, which leads to the definition of equipment parameters. In phase 2, new data is obtained by simulation, and the Exponentially Weighted Moving Average charts are applied considering flexible limits.info:eu-repo/semantics/publishedVersio

    Phytochemical Analysis and Antimicrobial, Antinociceptive, and Anti-Inflammatory Activities of Two Chemotypes of Pimenta pseudocaryophyllus

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    Preparations from Pimenta pseudocaryophyllus (Gomes) L.R. Landrum (Myrtaceae) have been widely used in Brazilian folk medicine. This study aims to evaluate the antimicrobial activity of the crude ethanol extracts, fractions, semipurified substances, and essential oils obtained from leaves of two chemotypes of P. pseudocaryophyllus and to perform the antinociceptive and anti-inflammatory screening. The ethanol extracts were purified by column chromatography and main compounds were spectrally characterised (1D and 2D 1H and 13C NMR). The essential oils constituents were identified by GC/MS. The broth microdilution method was used for testing the antimicrobial activity. The abdominal contortions induced by acetic acid and the ear oedema induced by croton oil were used for screening of antinociceptive and anti-inflammatory activities, respectively. The phytochemical analysis resulted in the isolation of pentacyclic triterpenes, flavonoids, and phenol acids. The oleanolic acid showed the best profile of antibacterial activity for Gram-positive bacteria (31.2–125 μg mL−1), followed by the essential oil of the citral chemotype (62.5–250 μg mL−1). Among the semipurified substances, Ppm5, which contained gallic acid, was the most active for Candida spp. (31.2 μg mL−1) and Cryptococcus spp. (3.9–15.6 μg mL−1). The crude ethanol extract and fractions from citral chemotype showed antinociceptive and anti-inflammatory effects

    Solar and Interplanetary Turbulence: Lagrangian Coherent Structures

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    Talk delivered in 22nd EGU General Assembly, held online 4-8 May, 2020, id.4289, https://meetingorganizer.copernicus.org/EGU2020/EGU2020-4289.html.-- https://www.egu2020.eu/The dynamics of solar and interplanetary plasmas is governed by coherent structures such as current sheets and magnetic flux ropes which are responsible for the genesis of intermittent turbulence via magnetic reconnections in solar supergranular junctions, solar coronal loops, the shock-sheath region of an interplanetary coronal mass ejection, and the interface region of two interplanetary magnetic flux ropes. Lagrangian coherent structures provide a new powerful technique to detect time- or space-dependent transport barriers, and objective (i.e., frame invariant) kinematic and magnetic vortices in space plasma turbulence. We discuss the basic concepts of Lagrangian coherent structures in plasmas based on the computation of the finite-time Lyapunov exponent, the Lagrangian averaged vorticity deviation and the integrated averaged current deviation, as well as their applications to numerical simulations of MHD turbulence and space and ground observations.With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation SEV-2017-070

    Influence of fruit biotypes on the chemical composition and antifungal activity of the essential oils of eugenia uniflora leaves

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    The multivariate chemical analysis of essential oils of Eugenia uniflora leaves with different fruit colours indicated the presence of three oil clusters regarding sample biotypes. The first cluster included yellowish, dark red and purple fruits with high percentages of germacrene B (11.1-30.7%), germacrone (9.8-54%) and atractylone (0-19.9%). In cluster II, with bright red fruit samples, the major constituents were curzerene (42.0-43.2%), germacrene D (8.7-9.0%) and germacrene A (5.9-8.9%), whereas cluster III included red-orange fruit samples containing high contents of selina-1,3,7(11)-trien-8-one (40.3-55.4%) and selina-1,3,7(11)-trien-8-one epoxide (12.7-24.4%). The clustered oils were investigated against the systemic fungus Paracoccidioides brasiliensis via the broth macrodilution method. The oil from cluster II revealed the most significant result. The yeast form of P. brasiliensis was completely inhibited at a concentration of 62.5 µg mL-1

    Structural studies of a lipid-binding peptide from tunicate hemocytes with anti-biofilm activity

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    This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/Clavanins is a class of peptides (23aa) histidine-rich, free of post-translational modifications. Clavanins have been studied largely for their ability to disrupt bacterial membranes. In the present study, the interaction of clavanin A with membranes was assessed by dynamic light scattering, zeta potential and permeabilization assays. We observed through those assays that clavanin A lysis bacterial cells at concentrations corresponding to its MIC. Further, the structure and function of clavanin A was investigated. To better understand how clavanin interacted with bacteria, its NMR structure was elucidated. The solution state NMR structure of clavanin A in the presence of TFE-d3 indicated an α-helical conformation. Secondary structures, based on circular dichroism measurements in anionic sodium dodecyl sulfate (SDS) and TFE (2,2,2-trifluorethanol), in silico lipid-peptide docking and molecular simulations with lipids DPPC and DOPC revealed that clavanin A can adopt a variety of folds, possibly influencing its different functions. Microcalorimetry assays revealed that clavanin A was capable of discriminating between different lipids. Finally, clavanin A was found to eradicate bacterial biofilms representing a previously unrecognized function.We would like to thank CNPq, CAPES (Ciências sem Fronteiras), FAPDF and FUNDECT. D.G. acknowledges Fundação para a Ciência e a Tecnologia - Ministério da Educação e Ciência (FCT-MEC, Portugal) for fellowship SFRH/BPD/73500/2010 and A.S.V. for funding within the FCT Investigator Programme (IF/00803/2012).info:eu-repo/semantics/publishedVersio

    Onset and End of the Rainy Season in South America in Observations and the ECHAM 4.5 Atmospheric General Circulation Model

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    Rainfall in South America as simulated by a 24-ensemble member of the ECHAM 4.5 atmospheric general circulation model is compared and contrasted with observations (in areas in which data are available) for the period 1976–2001. Emphasis is placed on determining the onset and end of the rainy season, from which its length and rain rate are determined. It is shown that over large parts of the domain the onset and ending dates are well simulated by the model, with biases of less than 10 days. There is a tendency for model onset to occur early and ending to occur late, resulting in a simulated rainy season that is on average too long in many areas. The model wet season rain rate also tends to be larger than observed. To estimate the relative importance of errors in wet season length and rain rate in determining biases in the annual total, adjusted totals are computed by substituting both the observed climatological wet season length and rate for those of the model. Problems in the rain rate generally are more important than problems in the length. The wet season length and rain rate also contribute substantially to interannual variations in the annual total. These quantities are almost independent, and it is argued that they are each associated with different mechanisms. The observed onset dates almost always lie within the range of onset of the ensemble members, even in the areas with a large model onset bias. In some areas, though, the model does not perform well. In southern Brazil the model ensemble average onset always occurs in summer, whereas the observations show that winter is often the wettest period. Individual members, however, do occasionally show a winter rainfall peak. In southern Northeast Brazil the model has a more distinct rainy season than is observed. In the northwest Amazon the model annual cycle is shifted relative to that observed, resulting in a model bias. No interannual relationship between model and observed onset dates is expected unless onset in the model and observations has a mutual relationship with SST anomalies. In part of the near-equatorial Amazon, there does exist an interannual relationship between onset dates. Previous studies have shown that in this area there is a relationship between SST anomalies and variations in seasonal total rainfall

    Produtividade e vigor do maracujazeiro-amarelo plantado em covas e plantio direto sob manejo orgânico.

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    O objetivo deste trabalho foi avaliar o vigor e a produtividade do maracujazeiro-amarelo plantado em diferentes tamanhos de cova e plantio direto sob manejo orgânico. O experimento foi conduzido de 2005 a 2007, no Setor de Agricultura Ecológica da Universidade Federal do Acre, em delineamento de blocos casualizados, constituídos de cinco tratamentos, quatro repetições e quatro plantas por parcela. Foram avaliados cinco tipos de preparo do solo: T1 cova do tamanho do torrão (0,19 x 0,063m) com adubação em cobertura; T2 cova de 0,30 x 0,30 x 0,30m com adubação de plantio na cova; T3 cova de 0,30 x 0,30 x 0,30m com adubação de plantio em cobertura; T4 cova de 0,50 x 0,50 x 0,50m com adubação de plantio na cova; e T5 cova de 0,50 x 0,50 x 0,50m com adubação de plantio em cobertura. O tamanho da cova e o plantio direto não influenciaram o vigor da planta e a biomassa de raízes. O número de frutos por planta e a produtividade, na segunda e na somatória das duas safras, foram maiores com plantio direto e com covas cúbicas de 0,30m. Após dois anos de cultivo, a densidade do solo foi maior na camada de 0-5cm de profundidade num raio de 20cm da planta para o plantio em covas de 0,50m com adubação na cova e menor para o plantio direto, não havendo diferença entre os demais tratamentos. O plantio direto ou o plantio em covas pequenas com dimensões de 0,30 x 0,30 x 0,30m proporcionou maior produtividade de maracujá que o plantio em covas maiores, mesmo não influenciando o vigor das plantas e a massa seca de raízes
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