Magnetic Field Tomography

Neutral atoms may be trapped via the interaction of their magnetic dipole moment with magnetic field gradients. One of the possible schemes is the cloverleaf trap. It is often desirable to have at hand a fast and precise technique for measuring the magnetic field distribution. We introduce a novel diagnostic tool for instantaneous imaging the equipotential lines of a magnetic field within a region of space (the vacuum recipient) that is not accessible to massive probes. Our technique is based on spatially resolved observation of the fluorescence emitted by a hot beam of sodium atoms crossing a thin slice of resonant laser light within the magnetic field region to be investigated. The inhomogeneous magnetic field spatially modulates the resonance condition between the Zeeman-shifted hyperfine sublevels and the laser light and therefore the amount of scattered photons. We demonstrate this technique by mapping the field of our cloverleaf trap in three dimensions under various conditions.Comment: 8 pages, 8 figure

Emergence of turbulence in an oscillating Bose-Einstein condensate

We report on the experimental observation of vortices tangle in an atomic BEC of Rb-87 atoms when an external oscillatory perturbation is introduced in the trap. The vortices tangle configuration is a signature of the presence of a turbulent regime in the cloud. We also show that this turbulent cloud has suppression of the aspect ratio inversion typically observed in quantum degenerate bosonic gases during free expansion. Instead, the cloud expands keeping the ratio between their axis constant. Turbulence in atomic superfluids may constitute an alternative system to investigate decay mechanisms as well as to test fundamental theoretical aspects in this field.Comment: accepted for Phys. Rev. Let

Mepiquat chloride application on cotton at variable rate.

Mepiquat chloride (1.1 - dimethylpiperidinium chloride) are used to control excessive vegetative growth in cotton (Gossypium hirsutum L.) broadcast sprayed by ground or air. As proven by previous researches the variability of the cotton plants height in the field is large enough to justify the application of Mepiquat at variable rate. The major advantages of it are: (i) yield increase; (ii) economy of the applied input; (iii) reducing the potential of environmental pollution. The main objective of this project was to develop a prototype device capable to accomplish the application of Mepiquat at variable rate in real time. This project used an equipment previously developed for automatic mapping of the cotton plants height based on ultrasound transducers. An electronic control device for ground sprayers was designed and constructed based on microcontroller PIC, using open source tools as Java, Linux operational system and IDE Netbeans. The device controls the pressure and flow in the spray line and uses Varitarget® nozzles due to its characteristics of linearity of flow and pressure. The calculation of the Mepiquat dosage to be applied is based on the obtained information of the plants heights and the map of previous application. The laboratory results demonstrate the accuracy of the equipment, with low response time considering the commercial sprayers velocity (3 m.s-1 to 5 m.s-1)

Caracterização física da madeira de Eucalyptus badjensis no sentido medula-casca.

Resumo

Emerging pleiotropic mechanisms underlying aluminum resistance and phosphorus acquisition on acidic soils.

Aluminum (Al) toxicity on acidic soils significantly damages plant roots and inhibits root growth. Hence, crops intoxicated by Al become more sensitive to drought stress and mineral nutrient deficiencies, particularly phosphorus (P) deficiency, which is highly unavailable on tropical soils. Advances in our understanding of the physiological and genetic mechanisms that govern plant Al resistance have led to the identification of Al resistance genes, both in model systems and in crop species. It has long been known that Al resistance has a beneficial effect on crop adaptation to acidic soils. This positive effect happens because the root systems of Al resistant plants show better development in the presence of soil ionic Al3C and are, consequently, more efficient in absorbing sub-soil water and mineral nutrients. This effect of Al resistance on crop production, by itself, warrants intensified efforts to develop and implement, on a breeding scale, modern selection strategies to profit from the knowledge of the molecular determinants of plant Al resistance. Recent studies now suggest that Al resistance can exert pleiotropic effects on P acquisition, potentially expanding the role of Al resistance on crop adaptation to acidic soils. This appears to occur via both organic acid (OA)- and non-OA transporters governing a joint, iron-dependent interplay between Al resistance and enhanced P uptake, via changes in root system architecture. Current research suggests this interplay to be part of a P stress response, suggesting that this mechanism could have evolved in crop species to improve adaptation to acidic soils. Should this pleiotropism prove functional in crop species grown on acidic soils, molecular breeding based on Al resistance genes may have a much broader impact on crop performance than previously anticipated. To explore this possibility, here we review the components of this putative effect of Al resistance genes on P stress responses and P nutrition to provide the foundation necessary to discuss the recent evidence suggesting pleiotropy as a genetic linkage between Al resistance and P efficiency. We conclude by exploring what may be needed to enhance the utilization of Al resistance genes to improve crop production on acidic soils.Article 1420

Efeito da deriva de herbicidas no desenvolvimento e na produção de milho.

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