11,107 research outputs found

    Type I interferons in tuberculosis: Foe and occasionally friend

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    Tuberculosis remains one of the leading causes of mortality worldwide, and, despite its clinical significance, there are still significant gaps in our understanding of pathogenic and protective mechanisms triggered by Mycobacterium tuberculosis infection. Type I interferons (IFN) regulate a broad family of genes that either stimulate or inhibit immune function, having both host-protective and detrimental effects, and exhibit well-characterized antiviral activity. Transcriptional studies have uncovered a potential deleterious role for type I IFN in active tuberculosis. Since then, additional studies in human tuberculosis and experimental mouse models of M. tuberculosis infection support the concept that type I IFN promotes both bacterial expansion and disease pathogenesis. More recently, studies in a different setting have suggested a putative protective role for type I IFN. In this study, we discuss the mechanistic and contextual factors that determine the detrimental versus beneficial outcomes of type I IFN induction during M. tuberculosis infection, from human disease to experimental mouse models of tuberculosis

    Soil fertility, mineral nitrogen and microbial biomass in upland soils of the Central Amazon under different plant covers.

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    Amazon is the largest State of Brazil and major area of the State is covered by a largest tropical rainforest of the world. Most soils of the Amazon region soils are characterized as acidic and infertile. When the Amazon forest land is cleared for agricultural use by burning the vegetation, the efficient nutrient recycling mechanism are disrupted. However, nutrient contents in the deforested burn land increased temporarily. The objective of this study was to evaluate the soil fertility, mineral nitrogen and microbial activity of carbon (C), nitrogen (N) and phosphorus (P) resulting from the replacement of the primary forest with pasture (Brachiaria brizantha), commercial plantations of rubber (Hevea spp.), cupuaçu (Theobroma grandiflorum), and citrus trees (Citrus sinensis) cultivated in Xanthic Ferralsol and secondary forest under Acrisols Dystric Nitosols. The results showed that ammonium-N predominates in the 0-10 cm soil depth both in primary forest and areas with secondary forest, citrus plantation and pasture. There was no increase in soil fertility with management of the cultivated areas under secondary forest, but in the pasture there was a significant increase in the stock of organic C and total N and high C/N ratios, the inverse of what occurred with the carbon of the microbial biomass. The primary forest had the highest values of C and P of the microbial biomass and the lowest metabolic quotient. Of the successions studied, the rubber trees were the plant cover with the smallest changes in terms of quality of the organic matter in the soil

    Repartição e remobilização de nutrientes na bananeira.

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    A bananeira demanda grandes quantidades de corretivos e fertilizantes para manter suas exigências nutricionais e obter alta produtividade, porém grande porcentagem aplicada não é disponibilizada, sendo perdida, principalmente, por fixação, lixiviação e volatilização. O objetivo deste trabalho foi verificar a taxa de remobilização e repartição de nutrientes na bananeira cultivar Thap Maeo, cultivada na Amazônia Ocidental. Os resultados mostraram que as maiores proporções de K, Na, Mg, S, B, Cu, Fe e Zn se encontram contidas no pseudocaule. Os restos florais da bananeira constituem forte dreno temporário de nutrientes. A biomassa proveniente dos restos de cultura representa fonte significativa de nutrientes para as plantas. O N e K apresentam o maior índice relativo de remobilização, sendo o inverso observado com o Mn e Fe. Termos para indexação: Musa sp., macronutrientes, micronutrientes, restos culturais

    Produção, fontes e nível crítico de boro para alfafa cultivada em Latossolo Vermelho Amarelo distrófico.

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    Com objetivo de determinar a dose, fontes e o nível crítico de boro que obtivesse a maior produção de matéria seca da alfafa foi realizado um experimento em condições de campo em delineamento em blocos casualisados com duas saturações por base, cinco doses (0, 1, 3, 6 e 9 kg ha-1 de B) e duas fontes [ulexita (9% de B) e ácido bórico (17% de B)], com quatro repetições. Foram realizados seis cortes com intervalos de 30 dias. Os resultados mostraram que o uso da ulexita ocasionou na maior produção de matéria seca da parte aérea (MSPA) da alfafa, sendo a maior produção obtida com aplicação estimada de 6,5 kg ha-1. O teor foliar de B para obtenção da maior produção de MSPA esta na faixa de 35,95 mg kg-1 a 37,35 mg kg-1

    Microbial biomass in upland soils of the Central Amazon under different plant covers.

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    The objective of this study was to evaluate the microbial activity of carbon, nitrogen and phosphorus resulting from the replacement of the primary forest with Brachiaria brizantha, Hevea, cupuaçu, citrus and secondary forest. There was no increase in soil fertility under secondary forest, but in the pasture had an increase in the stock of C and N and high C/N ratios, the inverse occurred with C-microbial biomass. The primary forest had the highest values of C, N and P of the microbial biomass and the lowest metabolic quotient. The Hevea was the plant cover with the smallest changes of C in the soil

    Yield and yield components of upland rice as influenced by nitrogen sources.

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    Ammonium sulfate and urea are main sources of nitrogen (N) for annual crop production in developing countries. Two greenhouse experiments were conducted using ammonium sulfate and urea as N sources for upland rice grown on a Brazilian Oxisol. The N rates used were 0, 50, 100, 150, 3000, and 400 kg N kg?1 of soil. Yield and yield components were significantly increased in a quadratic fashion with increasing N rate. Ammonium sulfate X urea interaction was significant for grain yield, shoot dry matter yield, panicle number, plant height and root dry weight, indicating a different response magnitude of these plant parameters to two sources of N. Based on regression equation, maximum grain yield was achieved with the application of 380 mg N kg?1 by ammonium sulfate and 271 mg N kg?1 by urea. Grain yield and yield components were reduced at higher rates of urea (>300 mg kg N) but these plant parameters? responses to ammonium sulfate at higher rates was constant. In the intermediate N rate range (125 to 275 mg kg?1), urea was slightly better compared to ammonium sulfate for grain yield. Grain yield was significantly related with plant height, shoot dry weight, panicle number, grain harvest index and root dry weight. Hence, improving these plant characteristics by using appropriate soil and plant management practices can improve upland rice yield

    5-State Rotation-Symmetric Number-Conserving Cellular Automata are not Strongly Universal

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    We study two-dimensional rotation-symmetric number-conserving cellular automata working on the von Neumann neighborhood (RNCA). It is known that such automata with 4 states or less are trivial, so we investigate the possible rules with 5 states. We give a full characterization of these automata and show that they cannot be strongly Turing universal. However, we give example of constructions that allow to embed some boolean circuit elements in a 5-states RNCA

    Thermodynamic potential with correct asymptotics for PNJL model

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    An attempt is made to resolve certain incongruities within the Nambu - Jona-Lasinio (NJL) and Polyakov loop extended NJL models (PNJL) which currently are used to extract the thermodynamic characteristics of the quark-gluon system. It is argued that the most attractive resolution of these incongruities is the possibility to obtain the thermodynamic potential directly from the corresponding extremum conditions (gap equations) by integrating them, an integration constant being fixed in accordance with the Stefan-Boltzmann law. The advantage of the approach is that the regulator is kept finite both in divergent and finite valued integrals at finite temperature and chemical potential. The Pauli-Villars regularization is used, although a standard 3D sharp cutoff can be applied as well.Comment: 16 pages, 5 figures, extended version, title change

    Multi-strata agroforestry system with native amazonian plants cultivated in acid soil.

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    Multi-strata agroforestry system is mentioned as the most promising option for the sustainable agriculture in infertile upland soil of Central Amazonian. However, studies showed that the sustainability practices are not adopted by the growers in this region. lhe objective of this study was to evaluate the soil fertility and nutritional state of native Amazon plant species grown on a Xanthic Ferralsol in an agroforestry system. Native plants species used were r five of timber species - Hevea brasiliensis (rubber), Ceiba pentandra- (kapok), Jacaranda copa ia (jacaranda), Buchenavia huber (cuiarana) and Trattinicka burserifolia (breu); two palm species - Bactris gasipaes (peach palm) and Euterpe oleracea (assai); and five fruit-bearing species - Rollinia mucosa (biriba), Theobroma cacao (cacao), Theobroma grandiflorum (cupuassu), Couma sorbilis (sorva) and Myrciaria dubia (camu-camu). The results showed that plants from the same ecosystem with acidity tolerance differ significantly in nutrient uptake efficiency and nutritional requirements, indicating the possibility of using appropriate species that can be used in an agroforestry system of central Amazon Region

    Resonant x-ray scattering study on multiferroic BiMnO3

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    Resonant x-ray scattering is performed near the Mn K-absorption edge for an epitaxial thin film of BiMnO3. The azimuthal angle dependence of the resonant (003) peak (in monoclinic indices) is measured with different photon polarizations; for the σπ\sigma\to\pi' channel a 3-fold symmetric oscillation is observed in the intensity variation, while the σσ\sigma\to\sigma' scattering intensity remains constant. These features are accounted for in terms of the peculiar ordering of the manganese 3d orbitals in BiMnO3. It is demonstrated that the resonant peak persists up to 770 K with an anomaly around 440 K; these high and low temperatures coincide with the structural transition temperatures, seen in bulk, with and without a symmetry change, respectively. A possible relationship of the orbital order with the ferroelectricity of the system is discussed.Comment: 14 pages, 4 figure
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