654 research outputs found

    Herbage Allowance and Nitrogen Fertilization Effects on Morphological Characteristics of \u3ci\u3ePaspalum notatum\u3c/i\u3e FlĂĽgge

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    The grazing study was conducted at the Estação Experimental Agronomica – UFRGS, 30o S, on a native pasture, to evaluate the leaf area index and structural morphological traits of bahiagrass (Paspalum notatum Fl.), within the requirements of a Central Composite Rotatable experimental design, providing for equal precision, with two blocks, encompassing two factors at five levels each, namely: Herbage Allowance (HA) = 4.0; 5.5; 9.0; 12.5 and 14.0 kg green dry matter per 100 kg liveweight per day (% LW), in association with Nitrogen (N) fertilization levels of 0; 30; 100; 170 and 200 kg ha-1 as urea, The leaf length and leaf area index (LAI) were increased as HA and N levels increased. The tiller density was increased at higher HA where the N contribution showed to be more effective. More lenient grazing also increased leaf life span and leaf lamina length, while N promoted canopy density and reduced leaf life span and number of leaves per tiller. The higher LAI values developed were accomplished by reduced tiller densities that supported small number of leaves per tiller, with increased leaf sizes

    Articulated blade tip devices for load alleviation on wind turbines

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    This paper investigates the load alleviation capabilities of an articulated tip device, where the outermost portion of the blade can rotate with respect to the rest of the blade. Passive, semi-passive and active solutions are developed for the tip rotation. In the passive and semi-passive configurations tip pitching is mainly driven by aerodynamic loads, while for the active case the rotation is obtained with an actuator commanded by a feedback control law. Each configuration is analyzed and tested using a high-fidelity aeroservoelastic simulation environment, by considering standard operative conditions as well as fault situations. The potential benefits of the proposed blade tip concepts are discussed in terms of performance and robustness

    Tyr78Phe Transthyretin Mutation with Predominant Motor Neuropathy as the Initial Presentation

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    Transthyretin (TTR) amyloidosis, the most frequent form of hereditary amyloidosis, is caused by dominant mutations in the TTR gene. More than 100 mutations have been identified. Clinical manifestations of TTR amyloidosis are usually induced by extracellular amyloid deposition in several organs. The major neurological manifestation is motor-sensory neuropathy associated with dysautonomic impairment. Here, we describe a 63-year-old man who came to our institution due to a suspected motor neuron disease. During a 4-year follow-up period, he underwent extensive clinical examination, electromyographic studies, sural nerve biopsy and TTR gene analysis by direct sequencing. Despite the predominant motor involvement, the detailed clinical examination also showed some mild sensory and dysautonomic signs. In addition, his clinical and family history included multiorgan disorders, such as carpal tunnel syndrome, as well as conditions with cardiac, renal, eye, and hepatic involvement. The sural nerve biopsy disclosed amyloid deposition, and the sequence analysis of the TTR gene detected a heterozygous Tyr78Phe substitution. The TTR gene variant found in our patient had only been described once so far, in a French man of Italian origin presenting with late-onset peripheral neuropathy and bilateral carpal tunnel syndrome. The predominant motor involvement presented by our patient is an uncommon occurrence and demonstrates the clinical heterogeneity of TTR amyloidosis

    Identification and rejection of scattered neutrons in AGATA

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    Gamma rays and neutrons, emitted following spontaneous fission of 252Cf, were measured in an AGATA experiment performed at INFN Laboratori Nazionali di Legnaro in Italy. The setup consisted of four AGATA triple cluster detectors (12 36-fold segmented high-purity germanium crystals), placed at a distance of 50 cm from the source, and 16 HELENA BaF2 detectors. The aim of the experiment was to study the interaction of neutrons in the segmented high-purity germanium detectors of AGATA and to investigate the possibility to discriminate neutrons and gamma rays with the gamma-ray tracking technique. The BaF2 detectors were used for a time-of-flight measurement, which gave an independent discrimination of neutrons and gamma rays and which was used to optimise the gamma-ray tracking-based neutron rejection methods. It was found that standard gamma-ray tracking, without any additional neutron rejection features, eliminates effectively most of the interaction points due to recoiling Ge nuclei after elastic scattering of neutrons. Standard tracking rejects also a significant amount of the events due to inelastic scattering of neutrons in the germanium crystals. Further enhancements of the neutron rejection was obtained by setting conditions on the following quantities, which were evaluated for each event by the tracking algorithm: energy of the first and second interaction point, difference in the calculated incoming direction of the gamma ray, figure-of-merit value. The experimental results of tracking with neutron rejection agree rather well with Geant4 simulations

    Hybrid fibroin/polyurethane small-diameter vascular grafts: from fabrication to in vivo preliminary assessment

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    To address the need of alternatives to autologous vessels for small-calibre vascular applications (e.g. cardiac surgery), a bio-hybrid semi-degradable material composed of silk fibroin (SF) and polyurethane (Silkothane (R)) was herein used to fabricate very small-calibre grafts (o(in) = 1.5 mm) via electrospinning. Bio-hybrid grafts were in vitro characterized in terms of morphology and mechanical behaviour, and compared to similar grafts of pure SF. Similarly, two native vessels from a rodent model (abdominal aorta and vena cava) were harvested and characterized. Preliminary implants were performed on Lewis rats to confirm the suitability of Silkothane (R) grafts for small-calibre applications, specifically as aortic insertion and femoral shunt. The manufacturing process generated pliable grafts consisting of a randomized fibrous mesh and exhibiting similar geometrical features to rat aortas. Both Silkothane (R) and pure SF grafts showed radial compliances in the range from 1.37 +/- 0.86 to 1.88 +/- 1.01% 10(-2) mmHg(-1), lower than that of native vessels. The Silkothane (R) small-calibre devices were also implanted in rats demonstrating to be adequate for vascular applications; all the treated rats survived the surgery for three months after implantation, and 16 rats out of 17 (94%) still showed blood flow inside the graft at sacrifice. The obtained results lay the basis for a deeper investigation of the interaction between the Silkothane (R) graft and the implant site, which may deal with further analysis on the potentialities in terms of degradability and tissue formation, on longer time-points
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