6,036 research outputs found

    Hyperfine magnetic field in ferromagnetic graphite

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    Information on atomic-scale features is required for a better understanding of the mechanisms leading to magnetism in non-metallic, carbon-based materials. This work reports a direct evaluation of the hyperfine magnetic field produced at 13C nuclei in ferromagnetic graphite by nuclear magnetic resonance (NMR). The experimental investigation was made possible by the results of first-principles calculations carried out in model systems, including graphene sheets with atomic vacancies and graphite nanoribbons with edge sites partially passivated by oxygen. A similar range of maximum hyperfine magnetic field values (18-21T) was found for all systems, setting the frequency span to be investigated in the NMR experiments; accordingly, a significant 13C NMR signal was detected close to this range without any external applied magnetic field in ferromagnetic graphite

    Avaliação de classificadores automáticos no mapeamento de áreas cafeeiras da Região de Guaxupé, Minas Gerais.

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    O mapeamento da ocupação da terra constitui uma das mais importantes atividades de geração de dados para gerenciamento e monitoramento de ambientes agrícolas. Pretendeu-se neste trabalho avaliar a exatidão da interpretação visual de uma imagem SPOT 5 no mapeamento do café na região de Guaxupé, tendo como referência dados obtidos em campo, bem como comparar o desempenho de técnicas de mapeamento automático da mesma área em comparação com a interpretação visual,visando a avaliação da viabilidade de aplicação destas técnicas para agilizar o mapeamento do parque cafeeiro na região.Foram trabalhadas imagens SPOT 5 com resolução espacial de 10 metros e de 2,5 metros. A cena foi submetida ao processamento por diferentes métodos de classificação automática para a imagem com resolução de 10 metros e por interpretação visual para a imagem com resolução de 2,5 metros. Dados obtidos em campo foram tomados como referência para obtenção de índices de exatidão do mapeamento. Foram estratificadas as classes café, mata e outros usos, sendo esta última oriunda do agrupamento dos demais tipos de vegetação como culturas anuais, pastagens, solo exposto, áreas urbanas, etc. Os índices utilizados foram calculados de maneira a permitir a avaliação da exatidão global da classificação e também individualmente para a classe café

    Coffee water use in agroforestry system with rubber trees.

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    Water uptake and use by plants are essentially energy processes that can be largely modified by percentage of soil cover, plant type; foliage area and its distribution; phenological stage and several environmental factors. Coffee trees (Coffea arabica - cv. Obatã IAC 1669-20) in Agrforestry System (AFS) spaced 3.4x0.9m apart, were planted inside and along rows of 12- year-old rubber trees (Hevea spp.) in Piracicaba-SP, Brazil (22 42'30" S, 47 38'00" W - altitude: 546m). Sap flow of one-year-old coffee plants exposed to 35; 45; 80; 95 and 100% of total solar radiation was estimated by the heat balance technique (Dynamax Inc.). Coffee plants under shade showed greater water loss per unit of incident irradiance. On the other hand, plants in monocrop (full sun) had the least water loss per unit of incident irradiance. For the evaluated positions average water use was (gH2O.m-2Leaf area.MJ-1): 64.71; 67.75; 25.89; 33.54; 27.11 in Dec./2002 and 97.14; 72.50; 40.70; 32.78; 26.13 in Feb./2003. This fact may be attributed to the higher stomata sensitivity of the coffee plants under more illuminated conditions, thus plants under full sun presented the highest water use efficiency. Express transpiration by leaf mass can be a means to access plant adaptation to the various environments, which is inaccessible when the approach is made by leaf area

    Differential modulation of cancellous and cortical distal femur by fructose and natural mineral-rich water consumption in ovariectomized female sprague dawley rats

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    Bone mineral density (BMD) and microstructure depend on estrogens and diet. We assessed the impact of natural mineral-rich water ingestion on distal femur of fructose-fed estrogen-deficient female Sprague Dawley rats. Ovariectomized rats drank tap or mineral-rich waters, with or without 10%-fructose, for 10 weeks. A sham-operated group drinking tap water was included (n = 6/group). Cancellous and cortical bone compartments were analyzed by microcomputed tomography. Circulating bone metabolism markers were measured by enzyme immunoassay/enzyme-linked immunosorbent assay or multiplex bead assay. Ovariectomy significantly worsened cancellous but not cortical bone, significantly increased circulating degradation products from C-terminal telopeptides of type I collagen and receptor activator of nuclear factor-kappaB ligand (RANKL), and significantly decreased circulating osteoprotegerin and osteoprotegerin/RANKL ratio. In ovariectomized rats, in cancellous bone, significant water effect was observed for all microstructural properties, except for the degree of anisotropy, and BMD (neither a significant fructose effect nor a significant interaction between water and fructose ingestion effects were observed). In cortical bone, it was observed a significant (a) water effect for medullary volume and cortical endosteal perimeter; (b) fructose effect for cortical thickness, medullary volume, cross-sectional thickness and cortical endosteal and periosteal perimeters; and (c) interaction effect for mean eccentricity. In blood, significant fructose and interaction effects were found for osteoprotegerin (no significant water effect was seen). For the first time in ovariectomized rats, the positive modulation of cortical but not of cancellous bone by fructose ingestion and of both bone locations by natural mineral-rich water ingestion is described.This work was supported by FEDER—Fundo Europeu de Desenvolvimento Regional (through NORTE 2020 Programa Operacional Regional do Norte—NORTE-01-0145-FEDER-000012), Unicer Bebidas, S.A., Portugal and by FCT—Fundação para a Ciência e Tecnologia (SFRH/BDE/33798/2009 to CP; SFRH/BD/71149/2010 to EP; SFRH/BD/79716/2011 to NS and UID/BIM/04293/2013 to Instituto de Investigação e Inovação em Saúde (Projeto Estratégico)). When considering the funding by Unicer Bebidas, S.A., it should be mentioned that the study here presented was developed, in its full extent, both in scientific terms and research equipment conditions, independently of the beverage company

    Volatilização de amônia de adubos nitrogenados aplicados no feijoeiro irrigado cultivado no sistema plantio direto.

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    Este trabalho teve como objetivo avaliar as perdas de N por volatilização de NH3, com a aplicação de diferentes fontes nitrogenadas no feijoeiro cultivado em sistema plantio direto no inverno

    Skeletopy of the intumescentia lumbalis and conus medullaris applied to epidural anaesthesia in Leopardus geoffroyi

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    Background: Leopardus geoffroyi is a Neotropical wild felid with wide distribution in the south of the South American continent. The objective was to investigate the skeletopy of the intumescentia lumbalis (IL) and conus medullaris (CM) from 11 specimens of L. geoffroyi collected dead on highways. Materials and methods: The cadavers were fixed in formaldehyde solution and dissected to allow the dorsal exposure of IL and CM. The cranial and caudal limits were marked with radiopaque pins and radiographic projections were used to determine the skeletopy. The lengths of IL and CM were measured with a pachymeter. Results: In most specimens, the IL was located at the level of L4 and L5 vertebrae, although in 4 (1 male and 3 females) individuals its cranial limit was L3 and in 3 specimens (2 male and 1 female) the caudal limit was L6. The length of IL was 35.6 ± 6.7 mm. The CM had its base predominantly at the level of the L5 vertebra, although in some specimens the base was in L4 and in others in L6. The apex of the CM can be found since the lumbosacral junction until the level of the Cd2 vertebra. The CM measured 74.4 ± 14.3 mm. Conclusions: Based on the skeletopy, it can be suggested that epidural anaesthesia procedures in L. geoffroyi are safer with the introduction of the catheter through the sacrocaudal interarcual space, as recommended by some anaesthetists for the domestic cat

    Opioid pain medication prescription for chronic pain in primary care centers: the roles of pain acceptance, pain intensity, depressive symptoms, pain catastrophizing, sex, and age

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    Background: Psychological factors of patients may influence physicians’ decisions on prescribing opioid analgesics. However, few studies have sought to identify these factors. The present study had a double objective: (1) To identify the individual factors that differentiate patients who had been prescribed opioids for the management of chronic back pain from those who had not been prescribed opioids and (2) to determine which factors make significant and independent contributions to the prediction of opioid prescribing. Methods: A total of 675 patients from four primary care centers were included in the sample. Variables included sex, age, pain intensity, depressive symptoms, pain catastrophizing, and pain acceptance. Results: Although no differences were found between men and women, participants with chronic noncancer pain who were prescribed opioids were older, reported higher levels of pain intensity and depressive symptoms, and reported lower levels of pain-acceptance. An independent association was found between pain intensity and depressive symptoms and opioid prescribing. Conclusions: The findings suggest that patient factors influence physicians’ decisions on prescribing opioids. It may be useful for primary care physicians to be aware of the potential of these factors to bias their treatment decisions.info:eu-repo/semantics/publishedVersio
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