91 research outputs found

    Physiological responses to folate overproduction in lactobacillys plantarum WCFS1.

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    <p>Abstract</p> <p>Background</p> <p>Using a functional genomics approach we addressed the impact of folate overproduction on metabolite formation and gene expression in <it>Lactobacillus plantarum </it>WCFS1. We focused specifically on the mechanism that reduces growth rates in folate-overproducing cells.</p> <p>Results</p> <p>Metabolite formation and gene expression were determined in a folate-overproducing- and wild-type strain. Differential metabolomics analysis of intracellular metabolite pools indicated that the pool sizes of 18 metabolites differed significantly between these strains. The gene expression profile was determined for both strains in pH-regulated chemostat culture and batch culture. Apart from the expected overexpression of the 6 genes of the folate gene cluster, no other genes were found to be differentially expressed both in continuous and batch cultures. The discrepancy between the low transcriptome and metabolome response and the 25% growth rate reduction of the folate overproducing strain was further investigated. Folate production per se could be ruled out as a contributing factor, since in the absence of folate production the growth rate of the overproducer was also reduced by 25%. The higher metabolic costs for DNA and RNA biosynthesis in the folate overproducing strain were also ruled out. However, it was demonstrated that folate-specific mRNAs and proteins constitute 8% and 4% of the total mRNA and protein pool, respectively.</p> <p>Conclusion</p> <p>Folate overproduction leads to very little change in metabolite levels or overall transcript profile, while at the same time the growth rate is reduced drastically. This shows that <it>Lactobacillus plantarum </it>WCFS1 is unable to respond to this growth rate reduction, most likely because the growth-related transcripts and proteins are diluted by the enormous amount of gratuitous folate-related transcripts and proteins.</p

    Optical Hall conductivity of systems with gapped spectral nodes

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    We calculate the optical Hall conductivity within the Kubo formalism for systems with gapped spectral nodes, where the latter have a power-law dispersion with exponent n. The optical conductivity is proportional to n and there is a characteristic logarithmic singularity as the frequency approaches the gap energy. The optical Hall conductivity is almost unaffected by thermal fluctuations and disorder for n=1, whereas disorder has a stronger effect on transport properties if n=2

    Magnetic Catalysis: A Review

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    We give an overview of the magnetic catalysis phenomenon. In the framework of quantum field theory, magnetic catalysis is broadly defined as an enhancement of dynamical symmetry breaking by an external magnetic field. We start from a brief discussion of spontaneous symmetry breaking and the role of a magnetic field in its a dynamics. This is followed by a detailed presentation of the essential features of the phenomenon. In particular, we emphasize that the dimensional reduction plays a profound role in the pairing dynamics in a magnetic field. Using the general nature of underlying physics and its robustness with respect to interaction types and model content, we argue that magnetic catalysis is a universal and model-independent phenomenon. In support of this claim, we show how magnetic catalysis is realized in various models with short-range and long-range interactions. We argue that the general nature of the phenomenon implies a wide range of potential applications: from certain types of solid state systems to models in cosmology, particle and nuclear physics. We finish the review with general remarks about magnetic catalysis and an outlook for future research.Comment: 37 pages, to appear in Lect. Notes Phys. "Strongly interacting matter in magnetic fields" (Springer), edited by D. Kharzeev, K. Landsteiner, A. Schmitt, H.-U. Yee. Version 2: references adde

    Effects of environment on quality of tomato transplanting plants

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    Com a finalidade de verificar o efeito da adubação nitrogenada e intensidade luminosa sobre a qualidade das mudas de tomateiro cv Roma VF, foi instalado um experimento em con dições de estufa de vidro, no Setor de Horticultura da ESALQ, Piracicaba (SP). Os tratamentos consistiram em plantas sombreadas, com e sem adubação. Foram observados a altura, diâmetro do caule, e desenvolvimento do sistema radicular das mudas após 32 dias de germinação e os níveis de carboidratos e nitrato no caule. Dos resultados concluiu-se que a adubação nitrogenada na fase de muda é muito importante para se obter plantas sadias e fortes e em condições sombreadas, com adubação nitrogenada, as mudas são maiores, com alto teor de nitrato, enquanto que em condições de pleno sol e adubada, elas possuem maior diâmetro e sistema radicular mais desenvolvido.In order to study the effects of shading and unshading combined with N fertilizing on tomato transplanting plants, an experiment in greenhouse conditions was carried on. It was concluded that N is important to produce healthy and strong plants. Under shading plus N fertilization, plants are taller and have high nitrate contents, while under unshading plus N fertilization, plants have higher diameter and more developed root system

    Numerical simulations of the Warm-Hot Intergalactic Medium

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    In this paper we review the current predictions of numerical simulations for the origin and observability of the warm hot intergalactic medium (WHIM), the diffuse gas that contains up to 50 per cent of the baryons at z~0. During structure formation, gravitational accretion shocks emerging from collapsing regions gradually heat the intergalactic medium (IGM) to temperatures in the range T~10^5-10^7 K. The WHIM is predicted to radiate most of its energy in the ultraviolet (UV) and X-ray bands and to contribute a significant fraction of the soft X-ray background emission. While O VI and C IV absorption systems arising in the cooler fraction of the WHIM with T~10^5-10^5.5 K are seen in FUSE and HST observations, models agree that current X-ray telescopes such as Chandra and XMM-Newton do not have enough sensitivity to detect the hotter WHIM. However, future missions such as Constellation-X and XEUS might be able to detect both emission lines and absorption systems from highly ionised atoms such as O VII, O VIII and Fe XVII.Comment: 18 pages, 5 figures, accepted for publication in Space Science Reviews, special issue "Clusters of galaxies: beyond the thermal view", Editor J.S. Kaastra, Chapter 14; work done by an international team at the International Space Science Institute (ISSI), Bern, organised by J.S. Kaastra, A.M. Bykov, S. Schindler & J.A.M. Bleeke

    A hybrid semiconductor-glass waveguide laser

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    abstract .We report on a novel type of laser in which a semiconductor optical amplifier (SOA) receives frequency-selective feedback from a glass-waveguide circuit. The laser we present here is based on InP for operation in the 1.55 μm wavelength range. The Si3N4/SiO2 glass waveguide circuit comprises two sequential high-Q ring resonators. Adiabatic tapering is used for maximizing the feedback. The laser shows single-frequency oscillation with a record-narrow spectral linewidth of 24 kHz at an output power of 5.7 mW. The hybrid laser can be tuned over a broad range of 46.8 nm (1531 nm to 1577.8 nm). Such InP-glass hybrid lasers can be of great interest in dense wavelength division multiplexing (DWDM) and as phase reference in optical beam-forming networks (OBFN). The type of laser demonstrated here is also of general importance because it may be applied over a huge wavelength range including the visible, limited only by the transparency of glass (400 nm to 2.35 μm). © (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

    ARIA 2016: Care pathways implementing emerging technologies for predictive medicine in rhinitis and asthma across the life cycle

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    The Allergic Rhinitis and its Impact on Asthma (ARIA) initiative commenced during a World Health Organization workshop in 1999. The initial goals were (1) to propose a new allergic rhinitis classification, (2) to promote the concept of multi-morbidity in asthma a
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