989 resultados para Acesso radial
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To understand how tree growth has responded to recent climate warming, an understanding of the tree-climate-site complex is necessary. To achieve this, radial growth variability among 204 trees established before 1850 was studied in relation to both climatic and site factors. Seventeen forest stands were sampled in the Spanish Central Pyrenees. Three species were studied: Pinus uncinata, Abies alba, and Pinus sylvestris. For each tree, a ring-width residual chronology was built. All trees cross-dated well, indicating a common influence of the regional climate. For the 1952-1993 period, the radial growth of all species, especially P. uncinata, was positively correlated with warm Novembers during the year before ring formation and warm Mays of the year the annual ring formed. Differences in species-stand elevation modulated the growth-climate associations. Radial growth in P. uncinata at high elevation sites was reduced when May temperatures were colder and May precipitation more abundant. In the 20th century, two contrasting periods in radial growth were observed: one (1900-1949) with low frequency of narrow and wide rings, low mean annual sensitivity, and low common growth variation; and another (1950-1994) with the reverse characteristics. The increased variability in radial growth since the 1950s was observed for all species and sites, which suggests a climatic cause. The low shared variance among tree chronologies during the first half of the 20th century may result from a"relaxation" of the elevation gradient, allowing local site conditions to dominate macroclimatic influence. These temporal trends may be related to the recently reported increase of climatic variability and warmer conditions. This study emphasizes the need to carefully assess the relationships between radial growth and site conditions along ecological gradients to improve dendroclimatic reconstructions.
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BACKGROUND: Radial maze tasks have been used to assess optimal foraging and spatial abilities in rodents. The spatial performance was based on a capacity to rely on a configuration of local and distant cues. We adapted maze procedures assessing the relative weight of local cues and distant landmarks for arm choice in humans. NEW METHOD: The procedure allowed testing memory of places in four experimental setups: a fingertip texture-groove maze, a tactile screen maze, a virtual radial maze and a walking size maze. During training, the four reinforced positions remained fixed relative to local and distal cues. During subsequent conflict trials, these frameworks were made conflictive in the prediction of reward locations. RESULTS: Three experiments showed that the relative weight of local and distal relational cues is affected by different factors such as cues' nature, visual access to the environment, real vs. virtual environment, and gender. A fourth experiment illustrated how a walking maze can be used with people suffering intellectual disability. COMPARISON WITH EXISTING METHODS: In our procedure, long-term (reference) and short-term (working) memory can be assessed. It is the first radial task adapted to human that enables dissociating local and distal cues, to provides an indication as to their relative salience. Our mazes are moveable and easily used in limited spaces. Tasks are performed with realistic and spontaneous though controlled exploratory movements. CONCLUSION: Our tasks enabled highlighting the use of different strategies. In a clinical perspective, considering the use of compensatory strategies should orient towards adapted behavioural rehabilitation.
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BACKGROUND: Several guidelines recommend computed tomography scans for populations with high-risk for lung cancer. The number of individuals evaluated for peripheral pulmonary lesions (PPL) will probably increase, and with it non-surgical biopsies. Associating a guidance method with a target confirmation technique has been shown to achieve the highest diagnostic yield, but the utility of bronchoscopy with radial probe endobronchial ultrasound using fluoroscopy as guidance without a guide sheath has not been reported. METHODS: We conducted a retrospective analysis of bronchoscopy with radial probe endobronchial ultrasound using fluoroscopy procedures for the investigation of PPL performed by experienced bronchoscopists with no specific previous training in this particular technique. Operator learning curves and radiological predictors were assessed for all consecutive patients examined during the first year of application of the technique. RESULTS: Fifty-one PPL were investigated. Diagnostic yield and visualization yield were 72.5 and 82.3% respectively. The diagnostic yield was 64.0% for PPL ≤20mm, and 80.8% for PPL>20mm. No false-positive results were recorded. The learning curve of all diagnostic tools showed a DY of 72.7% for the first sub-group of patients, 81.8% for the second, 72.7% for the third, and 81.8% for the last. CONCLUSION: Bronchoscopy with radial probe endobronchial ultrasound using fluoroscopy as guidance is safe and simple to perform, even without specific prior training, and diagnostic yield is high for PPL>and ≤20mm. Based on these findings, this method could be introduced as a first-line procedure for the investigation of PPL, particularly in centers with limited resources.
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OBJETIVO: Estudar, retrospectivamente, as várias formas de apresentação da cicatriz radial/lesão esclerosante complexa (CR/LEC) na mamografia, correlacionando-as com o exame clínico e os achados ultra-sonográficos. Os achados histopatológicos e a associação da CR/LEC com hiperplasia atípica e carcinoma são discutidos. MATERIAIS E MÉTODOS: Foi realizado estudo retrospectivo de 926 lesões impalpáveis em 901 pacientes submetidas a biópsia excisional após localização pré-cirúrgica, do arquivo do Centro de Diagnóstico por Imagem e do Hospital Santa Rita, Vitória, ES, no período de outubro de 1993 a dezembro de 2001, nas quais 57 pacientes tiveram diagnóstico histopatológico de CR/LEC. RESULTADOS: A idade variou de 31 a 84 anos (média de 49 anos). As lesões foram palpáveis em dez casos. Na mamografia, 48 casos se apresentaram como distorção arquitetural, e com a mesma freqüência o nódulo espiculado e a densidade assimétrica, quatro casos cada. As microcalcificações foram detectadas na mamografia em 14 casos e em 20 quando o espécime cirúrgico foi avaliado. A ultra-sonografia foi realizada em 51 casos, tendo expressão em 17 como área hipoecóica irregular com atenuação acústica posterior. Houve 42 casos de CR/LEC sem ou com proliferação típica, nove casos com proliferação epitelial atípica e seis casos com carcinoma infiltrativo associado. CONCLUSÃO: Não é possível fazer diagnóstico diferencial de CR/LEC com câncer pelos métodos de imagem e a biópsia excisional deve ser realizada.
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AIMS: The aims of the study are to compare the outcome with and without major bleeding and to identify the independent correlates of major bleeding complications and mortality in patients described in the ATOLL study. METHODS: The ATOLL study included 910 patients randomly assigned to either 0.5 mg/kg intravenous enoxaparin or unfractionated heparin before primary percutaneous coronary intervention. Incidence of major bleeding and ischemic end points was assessed at 1 month, and mortality, at 1 and 6 months. Patients with and without major bleeding complication were compared. A multivariate model of bleeding complications at 1 month and mortality at 6 months was realized. Intention-to-treat and per-protocol analyses were performed. RESULTS: The most frequent bleeding site appears to be the gastrointestinal tract. Age >75 years, cardiac arrest, and the use of insulin or >1 heparin emerged as independent correlates of major bleeding at 1 month. Patients presenting with major bleeding had significantly higher rates of adverse ischemic complications. Mortality at 6 months was higher in bleeders. Major bleeding was found to be one of the independent correlates of 6-month mortality. The addition or mixing of several anticoagulant drugs was an independent factor of major bleeding despite the predominant use of radial access. CONCLUSIONS: This study shows that major bleeding is independently associated with poor outcome, increasing ischemic events, and mortality in primary percutaneous coronary intervention performed mostly with radial access.
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Intravascular brachytherapy with beta sources has become a useful technique to prevent restenosis after cardiovascular intervention. In particular, the Beta-Cath high-dose-rate system, manufactured by Novoste Corporation, is a commercially available 90Sr 90Y source for intravascular brachytherapy that is achieving widespread use. Its dosimetric characterization has attracted considerable attention in recent years. Unfortunately, the short ranges of the emitted beta particles and the associated large dose gradients make experimental measurements particularly difficult. This circumstance has motivated the appearance of a number of papers addressing the characterization of this source by means of Monte Carlo simulation techniques.
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For a massless fluid (density = 0), the steady flow along a duct is governed exclusively by viscous losses. In this paper, we show that the velocity profile obtained in this limit can be used to calculate the pressure drop up to the first order in density. This method has been applied to the particular case of a duct, defined by two plane-parallel discs. For this case, the first-order approximation results in a simple analytical solution which has been favorably checked against numerical simulations. Finally, an experiment has been carried out with water flowing between the discs. The experimental results show good agreement with the approximate solution
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The radial displacement of a fluid annulus in a rotating circular HeleShaw cell has been investigated experimentally. It has been found that the flow depends sensitively on the wetting conditions at the outer interface. Displacements in a prewet cell are well described by Darcy"s law in a wide range of experimental parameters, with little influence of capillary effects. In a dry cell, however, a more careful analysis of the interfacemotion is required; the interplay between a gradual loss of fluid at the inner interface, and the dependence of capillary forces at the outer interface on interfacial velocity and dynamic contact angle, result in a constant velocity for the interfaces. The experimental results in this case correlate in the form of an empirical scaling relation between the capillary number Ca and a dimensionless group, related to the ratio of centrifugal to capillary forces, which spans about three orders of magnitude in both quantities. Finally, the relative thickness of the coating film left by the inner interface is obtained as a function of Ca.
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Os procedimentos percutâneos orientados por imagem têm ganhado espaço crescente na radiologia intervencionista, constituindo ferramenta eficaz para a abordagem diagnóstica e terapêutica de massas e coleções nos diversos segmentos corporais. No entanto, localizações pélvicas profundas ainda representam grande desafio para o radiologista, por causa da interposição de estruturas anatômicas. Para que o procedimento seja bem sucedido é fundamental o planejamento da via de acesso baseado no conhecimento detalhado da anatomia radiológica da pelve. As principais vias de acesso para a abordagem destas lesões são: transabdominais (anterior e lateral), extraperitoneal ântero-lateral, transvaginal, transretal e transglútea. O objetivo deste trabalho é fazer uma revisão da anatomia seccional pélvica normal, demonstrando as diversas vias de acesso para biópsias e drenagens guiadas pela ultra-sonografia e pela tomografia computadorizada, bem como discutir as principais vantagens e complicações potenciais de cada uma delas.
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A series of bovine serum albumin-immobilized supports have been prepared and used as restricted access media (RAM) columns. Restricted-access supports combine size-exclusion of proteins and other high-molar-mass matrix components with the simultaneous enrichment of low-molar mass analytes. These characteristics were chromatographically evaluated for the columns. The RAM-BSA (Bovine Serum Albumin) columns showed excellent performance for exclusion of human plasma protein with good retention capacity for a series of acidic, basic, and neutral drugs.
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The performance of inductively-coupled plasma optical emission spectrometers with axial and radial views for determination of iodine in table salt was evaluated. Interference and memory effects in nitric acid and water-soluble tertiary amines (CFA-C) media were studied. Based on a factorial experiment, one optimum instrument operational condition for axial configuration, and two optima conditions for radial configuration was established. The ICP OES with axial view was 5-fold more sensitive than the radial view. Both matrix matching and standard addition methods were used for iodine quantification and for most samples, both strategies of calibration led to similar results. Recoveries ranged from 104 to 114%.
Effects of early thinning regime and tree status on the radial growth and wood density of Scots pine
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Modalidades de aprendizagem virtual combinadas com métodos convencionais de ensino podem contribuir na educação médica. Este estudo investigou o perfil de acesso e uso de portal universitário no ensino da Dermatologia. Trata-se de pesquisa quantitativa com questionário para avaliar emprego do portal universitário, perfil tecnológico dos estudantes, necessidades informacionais e uso de base de dados. A amostra foi composta por 122 acadêmicos na faixa etária de 23,7 ± 3,1 anos, com domínio da língua inglesa (93,4%) e acesso ao portal via internet domiciliar (77,9%) e dispositivos móveis (43,4%). As vantagens foram obtenção do conteúdo das aulas, recursos didáticos oferecidos e disponibilidade permanente. As dificuldades residiram em disponibilidade de rede no hospital-escola, aspectos técnicos e operacionais. Os acessos preferidos foram: aulas ilustradas, cronograma de provas e trabalhos, avisos editados, leituras obrigatórias, artigos, textos anexados e consultas a bibliotecas virtuais e revistas médicas. As bases de dados mais utilizadas foram: UpToDate (84,4%), Pubmed (77,9%) e Scielo 94 (77%). O portal atendeu as demandas informacionais dos graduandos,porém a utilidade percebida e a facilidade de uso deste recurso didático podem ser potencializadas para aplicação mais ampla na medicina.
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A ultra-estrutura e a composição química da madeira, bem como suas propriedades físicas e mecânicas, variam significativamente entre espécies, entre árvores de uma mesma espécie e, mesmo, entre diferentes partes de uma mesma árvore. Com este trabalho objetivou-se o estudo dos parâmetros de retratibilidade e de densidade básica da madeira Eucalyptus saligna, com idade de 16 anos, proveniente de talhões experimentais da EMBRAPA Florestas, de Colombo, Paraná. As amostras foram retiradas à altura do DAP de quatro posições eqüidistantes a partir da medula em direção à periferia, correspondendo a 0, 33, 66 e 100%, com dimensões nominais de 1,0 x 2,0 x 3,0 cm, sendo a última dimensão no sentido longitudinal. Elas foram mantidas em câmara fechada com ventilação, próximo de soluções salinas supersaturadas, com o objetivo de proporcionar diferentes condições de umidade relativa. Uma vez atingidas as distintas condições de umidade de equilíbrio, as amostras foram secas em estufa a 105 ºC e obtidos os dados de retratibilidade e densidade básica da madeira nas posições mencionadas. Constataram-se valores de contração volumétrica mais baixos na região medular, apresentando um acréscimo para as demais posições. Comportamento semelhante foi observado para os coeficientes das contrações lineares nas direções tangencial e radial. O fator anisotrópico foi consideravelmente mais elevado na região medular, decrescendo substancialmente em direção ao alburno. A densidade básica não mostrou sinais efetivos de estabilidade, apesar de mostrar tendência de aumento em direção à periferia do tronco.