633 research outputs found

    Electron spin as a spectrometer of nuclear spin noise and other fluctuations

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    This chapter describes the relationship between low frequency noise and coherence decay of localized spins in semiconductors. Section 2 establishes a direct relationship between an arbitrary noise spectral function and spin coherence as measured by a number of pulse spin resonance sequences. Section 3 describes the electron-nuclear spin Hamiltonian, including isotropic and anisotropic hyperfine interactions, inter-nuclear dipolar interactions, and the effective Hamiltonian for nuclear-nuclear coupling mediated by the electron spin hyperfine interaction. Section 4 describes a microscopic calculation of the nuclear spin noise spectrum arising due to nuclear spin dipolar flip-flops with quasiparticle broadening included. Section 5 compares our explicit numerical results to electron spin echo decay experiments for phosphorus doped silicon in natural and nuclear spin enriched samples.Comment: Book chapter in "Electron spin resonance and related phenomena in low dimensional structures", edited by Marco Fanciulli. To be published by Springer-Verlag in the TAP series. 35 pages, 9 figure

    UK export performance research - review and implications

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    Previous research on export performance has been criticized for being a mosaic of autonomous endeavours and for a lack of theoretical development. Building upon extant models of export performance, and a review and analysis of research on export performance in the UK for the period 1990-2005, an integrated model of export performance is developed and theoretical explanations of export performance are put forward. It is suggested that a multi-theory approach to explaining export performance is viable. Management and policy implications for the UK emerging from the review and synthesis of the literature and the integrated model are discussed

    The in vitro bioactivity of two novel hydrophilic, partially degradable bone cements

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    Composite bone cements were prepared with bioactive glasses (MgO–SiO2–3CaO Æ P2O5) of different reactivities. The matrix of these so-called hydrophilic, partially degradable and bioactive cements was composed of a starch/cellulose acetate blend and poly(2-hydroxyethyl methacrylate). The addition of 30 wt.% of glasses to this system made them bioactive in acellular medium: a dense apatite layer formed on the surface after 7 days of immersion in simulated body fluid. This was demonstrated both by microscopic and infrared spectroscopic techniques. The composition of the glass and, consequently, its structure was found to have important effects on the rate of the apatite formation. The combination of reactivity obtained by one formulation with the hydrophilic and degradable character of these cements makes them a very promising alternative to conventional acrylic bone cements, by allowing a better stabilization of the implant and a stronger adhesion to the bone

    Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

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    A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

    Apoio Matricial Como Articulador Das Relações Interprofissionais Entre Serviços Especializados E Atenção Primária à Saúde

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    This paper sought to carry out an integrative review of the national production on Matrix Support methodology, whilst encompassing empirical studies on effectiveness and theoretical-methodological review papers on Matrix Support. The used material is comprised of papers that are indexed in the PubMed database, the NLM and the BVS (Virtual Library of Health), between 1999 and 2013, in Portuguese, English and Spanish. We included 28 articles, and its analysis allowed the identification of three categories: 1) foundation goods and consolidation of the concept of matrix support; 2) Review articles on the matrix support; 3) Items arising from empirical research involving the concept of matrix support. The publications showed that the matrix support brings an innovative proposal and powerful to transform the health care model. However, to achieve their goals is necessary to overcome some impasses, several interconnected directly with the implementation of their directives and to overcoming structural problems of the National Health System (SUS). © 2016, Institute de Medicina Social da UERJ. All rights reserved.26245548

    Haematological and biochemical parameters in Churra-da-Terra-Quente ewes from the northeast of Portugal

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    Hematological and biochemical parameters, including plasma electrolytes and thyroid hormones, were determined in 73 clinically healthy Churra-da-Terra-Quente ewes, a typical breed from the northeast of Portugal. The hemogram values were: erythrocytes 9.8±1.51012/L; haemoglobin 118.1±19.1g/L; haematocrit 40.8±5.9%; leukocytes 5.7±1.8109/L; and platelets 544.3±177.2109/L. The thrombin time was 17.3±1.7 seconds. The values of biochemical parameters were: total protein 76.4±6.1g/L; glucose 2.87±0.60mmol/L; total cholesterol 1.65±0.33mmol/L; aspartate aminotransferase 155.9±49.2U/L; alanine aminotransferase 23.2±9.6U/L; γ-glutamyl transferase 48.0±18.7U/L; total alkaline phosphatase 121.6±76.1U/L; glutamate dehydrogenase 6.4±3.7U/L; urea 7.32±2.22mmol/L; creatinine 123.0±54.1μmol/L; total calcium 2.53±0.25mmol/L; phosphorus 2.10±0.46mmol/L; magnesium 1.01±0.09mmol/L; sodium 152.04±3.65mmol/L; potassium 4.7±0.4mmol/L; ionized calcium 1.32±0.07mmol/L; total thyroxine 111.75±42.29nmol/L; total triiodothyronine 1.01±0.28nmol/L; free T4 11.93±1.78pmol/L; free T3 4.22±1.33pmol/L; and thyroid-stimulating hormone 0.18±0.19μIU/mL. Although differences among the Churra-da-Terra-Quente breed and other breeds may occur, the hematological and biochemical parameters, plasma electrolytes, and thyroid hormones, for this indigenous breed, were generally situated within the reference intervals previously reported for sheep

    Morphophysiological Plasticity Of Plagiotropic Branches In Response To Change In The Coffee Plant Spacing Within Rows

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    Changes in spacing within rows may alter the morphology of the coffee plant by affecting the physiological constituents of its productivity. Even though some common plant responses to crop spacing variation are known, there is yet no scientific evidence that elucidates the effects of decreased spacing on the sourcesink relation in plagiotropic branches and, its association with both productivity and eco-physiological aspects of coffee leaves, mainly for new coffee cultivars in the Brazilian savannah. The aim of this work was to characterize the morphophysiological responses of Coffea arabica L. cultivars subjected to different spacing between plants within rows. Four Arabica coffee cultivars (Catuaí Vermelho IAC 144, Catuaí Amarelo IAC 62, Catuaí Amarelo IAC 32, and Tupi RN IAC 1669-13) were transplanted in January 2010. A row spacing of 0.40, 0.50, 0.60, 0.70, and 0.80 m was adopted between plants, maintaining a 3.80-m constant between rows. A randomized block design with four replicates was applied. During the experimental period, several morphophysiological characteristics of plagiotropic fruiting branches were evaluated in the months of April and December in 2013 and, in April 2014. The evaluation was conducted based on two canopy positions; canopy toward the rows, representing low exposure to light or toward the inter-row spacing, representing high light exposure. Leaf gas exchange, chlorophyll fluorescence, and photosynthetic pigments levels were minimally or not at all affected by changing either the coffee cultivars or plant spacing. During the first evaluation, the leaf-to-fruitratio linearly increased, regardless of the cultivar. Light-exposed branches showed higher content of carotenoids and chlorophyll a in leaves and lower leaf-to-fruit-ratio as compared to those within the plant canopy. A major reduction in the number of fruits per branch was observed which was closely related to a parallel decrease in the number of fruits per node but not in the number of fruiting nodes per branch. Although this response was largely cultivar-dependent, it also changed according to the branch position in the hedgerow. Our results suggest that all tested cultivars exhibit high morphophysiological plasticity and have the potential to grow under different plant spacing within rows.3763819383

    Food Extract of Purple Yam (Dioscorea trifida L.f.) from Brazil: Optimization of Extraction Method, Characterization, In Vivo Toxicity, and Antimicrobial Activity

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    Purple yam (Dioscorea trifida) has high agricultural productivity in the Amazon region but has not been much investigated. Multivariate strategies were employed to optimize the method to obtain a food extract rich in functional compounds. The optimal conditions showed that the combination of 0.2 g of dried purple yam with 15 mL of citric acid (1%) under agitation in a water bath at 36 °C for 4 min yields an extract with a high content of peonidin-3-O-glucoside-5-O-glucoside, peonidin-3-O-feruloylglycosideum-5-O-glycosideum, peonidin-3-Op-coumaroylglycosideum-5-O-glycoside, quinic acid, apigenin 8-C-xyloside-6-C-glycoside (vicenin 3), quinic acid, apigenin 6-C-xyloside-8-C-glycoside (vicenin 1), and isorhamnetin-O-dihexoside. Our extract also presented 56.91 ± 0.76 mg 100 g−1 of total anthocyanins, 417.05 ± 11.37 mg 100 g−1 total carotenoids, and 493.09 ± 6.38 mg GAE 100 g−1 of total phenolic compounds. In a Galleria mellonella, in vivo model consumption safety was for up to 150 g by 70 kg of body weight. In addition, it inhibited the growth of Gram-negative bacteria (Salmonella typhimurium and Escherichia coli). The simple, fast, and ecofriendly extraction conditions, combined with the biological effects of our extract, gives us a great potential for its application in food or packaging technologies.This study was funded by the Coordination for the Improvement of Higher Education Personnel (Funding 001). The Foundation for Science and Technology (FCT, Portugal) provided financial support through national funds FCT/MCTES (PIDDAC) to CIMO (UIDB/00690/2020 and UIDP/00690/2020) and SusTEC (LA/P/0007/2021). The FCT through the institutional scientific employment program contract provided contract for L. Barros. The BPI La Caixa Foundation, within project titled “AquaeVitae—Thermal Water as a Source of Life and Health” — “PROMOVE – The future of the Interior” call 2020, provided contract for T. Silveira.info:eu-repo/semantics/publishedVersio
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