590 research outputs found

    Custo da implantação de sistemas de produção silvipastoris em São Carlos, SP.

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    Produção pecuária tradicional gerou um grande passivo ambiental. As preocupações recentes com qualidade da carne, bem-estar animal e proteção ambiental estão perfeitamente sintonizadas com sistemas de produção de base ecológica, como sistemas agroflorestais, e neste caso, com uma de suas modalidades, sistemas silvipastoris. Este trabalho tem por objetivo avaliar o custo de implantação de sistemas silvipastoris com espécies florestais nativas. Uma área de 11,7 ha formada com pastagens degradadas foi plantada com sete espécies florestais nativas em renques com três linhas de árvores espaçados de 15 m. O sistema 1 consiste da produção animal nas entrelinhas (integração pecuária-floresta) e o sistema 2 inlcui o cultivo agrícola nas entrelinhas com o objetivo de alimentação animal na seca (integração lavoura-pecuária-floresta). O custo total de implantação do sistema1 foi de R4.398,76/haeodosistema2foideR4.398,76/ha e o do sistema 2 foi de R4.446,72/ha

    Buckling-driven delamination of carbon nanotube forests

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    We report buckling-driven delamination of carbon nanotube (CNT) forests from their growth substrates when subjected to compression. Macroscale compression experiments reveal local delamination at the CNT forest-substrate interface. Results of microscale flat punch indentations indicate that enhanced CNT interlocking at the top surface of the forest accomplished by application of a metal coating causes delamination of the forest from the growth substrate, a phenomenon not observed in indentation of as-grown CNT forests. We postulate that the post-buckling tensile stresses that develop at the base of the CNT forests serve as the driving force for delamination

    Effects of morphology on the micro-compression response of carbon nanotube forests

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    This study reports the mechanical response of distinct carbon nanotube (CNT) morphologies as revealed by flat punch in situ nanoindentation in a scanning electron microscope. We find that the location of incipient deformation varies significantly by changing the CNT growth parameters. The initial buckles formed close to the growth substrate in 70 and 190 µm tall CNT forests grown with low pressure chemical vapor deposition (LPCVD) and moved to ~100 µm above the growth substrate when the height increased to 280 µm. Change of the recipe from LPCVD to CVD at pressures near atmospheric changed the location of the initial buckling event from the bottom half to the top half of the CNT forest. Plasma pretreatment of the catalyst also resulted in a unique CNT forest morphology in which deformation started by bending and buckling of the CNT tips. We find that the vertical gradients in CNT morphology dictate the location of incipient buckling. These new insights are critical in the design of CNT forests for a variety of applications where mechanical contact is important

    The EL2 trap in highly doped GaAs:Te

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    We have investigated highly doped GaAs:Te at different doping concentrations (>10(17) cm(-3)) to assess the presence of the EL2 trap. We have utilized both capacitance and current transient spectroscopy techniques. The crucial parameter for the detection of EL2 is the relative position of the electron quasi-Fermi level in the depletion region. The observed shift of the EL2 apparent activation energy with increasing doping concentration is also discussed

    Controlled generation of momentum states in a high-finesse ring cavity

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    A Bose-Einstein condensate in a high-finesse ring cavity scatters the photons of a pump beam into counterpropagating cavity modes, populating a bi-dimensional momentum lattice. A high-finesse ring cavity with a sub-recoil linewidth allows to control the quantized atomic motion, selecting particular discrete momentum states and generating atom-photon entanglement. The semiclassical and quantum model for the 2D collective atomic recoil lasing (CARL) are derived and the superradiant and good-cavity regimes discussed. For pump incidence perpendicular to the cavity axis, the momentum lattice is symmetrically populated. Conversely, for oblique pump incidence the motion along the two recoil directions is unbalanced and different momentum states can be populated on demand by tuning the pump frequency.Comment: Submitted to EPJ-ST Special Issue. 10 pages and 3 figure

    Quantum state engineering assisted by entanglement

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    We suggest a general scheme for quantum state engineering based on conditional measurements carried out on entangled twin-beam of radiation. Realistic detection schemes such as {\sc on/off} photodetection, homodyne detection and joint measurement of two-mode quadratures are analyzed in details. Imperfections of the apparatuses, such as nonunit quantum efficiency and finite resolution, are taken into account. We show that conditional {\sc on/off} photodetection provides a reliable scheme to verify nonclassicality, whereas conditional homodyning represents a tunable and robust source of squeezed light. We also describe optical teleportation as a conditional measurement, and evaluate the degrading effects of finite amount of entanglement, decoherence due to losses, and nonunit quantum efficiency.Comment: Some pics with low resolution. Originals at http://www.qubit.i

    N6L pseudopeptide interferes with nucleophosmin protein-protein interactions and sensitizes leukemic cells to chemotherapy.

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    Abstract NPM1 is a multifunctional nucleolar protein implicated in several processes such as ribosome maturation and export, DNA damage response and apoptotic response to stress stimuli. The NPM1 gene is involved in human tumorigenesis and is found mutated in one third of acute myeloid leukemia patients, leading to the aberrant cytoplasmic localization of NPM1. Recent studies indicated that the N6L multivalent pseudopeptide, a synthetic ligand of cell–surface nucleolin, is also able to bind NPM1 with high affinity. N6L inhibits cell growth with different mechanisms and represents a good candidate as a novel anticancer drug for a number of malignancies of different histological origin. In this study we investigated whether N6L treatment could drive antitumor effect in acute myeloid leukemia cell lines. We found that N6L binds NPM1 at the N-terminal domain, co-localizes with cytoplasmic, mutated NPM1, and interferes with its protein-protein associations. N6L toxicity appears to be p53 dependent but interestingly, the leukemic cell line harbouring the mutated form of NPM1 is more resistant to treatment, suggesting that NPM1 cytoplasmic delocalization confers protection from p53 activation. Moreover, we show that N6L sensitizes AML cells to doxorubicin and cytarabine treatment. These studies suggest that N6L may be a promising option in combination therapies for acute myeloid leukemia treatment

    Corporate sponsorship of physical activity promotion programmes: part of the solution or part of the problem?

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    Background Parklives is a programme intended to raise levels of physical activity across the UK, funded by Coca-Cola GB and delivered in association with Local Authorities and other organizations. Such public-private partnerships have been advocated by many however critics suggest that the conflict between stakeholder motives is too great. Methods This study conducted a content analysis of twitter content related to the ParkLives physical activity programme. Images and text were analysed from two separate weeks, one from the school vacation period and one during school term time. Results Three hundred and eighteen tweets were analysed. Content analysis revealed 79% of images contained children and 45% of these images contained prominent Coca-Cola branding, a level of exposure that suggests ParkLives simultaneously provides opportunities for children's physical activity and for targeted marketing. Content analysis also demonstrated that the programme allowed increased access to policy-makers. Conclusions The sponsorship of a physical activity promotion campaign can allow a corporation to target its marketing at children and gain access to health-related policy development networks. This study reinforces the need for independent evaluation of all potential impacts of such a partnership and calls on those responsible for community health to fully consider the ethical implications of such relationships

    The PLASMONX Project for advanced beam physics experiments

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    The Project PLASMONX is well progressing into its design phase and has entered as well its second phase of procurements for main components. The project foresees the installation at LNF of a Ti:Sa laser system (peak power > 170 TW), synchronized to the high brightness electron beam produced by the SPARC photo-injector. The advancement of the procurement of such a laser system is reported, as well as the construction plans of a new building at LNF to host a dedicated laboratory for high intensity photon beam experiments (High Intensity Laser Laboratory). Several experiments are foreseen using this complex facility, mainly in the high gradient plasma acceleration field and in the field of mono- chromatic ultra-fast X-ray pulse generation via Thomson back-scattering. Detailed numerical simulations have been carried out to study the generation of tightly focused electron bunches to collide with laser pulses in the Thomson source: results on the emitted spectra of X-rays are presented
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