Stereoselective cycloaddition of 1-glucosyl-1,3-butadienes with tert-butyl 2H-azirine-3-carboxylate, glyoxylates and imines

Glucosyl dienes 1 have been reacted with the achiral 2H-azirine 4 and with glyoxylates, forming fused structures of type 5 and disaccharide-like compounds 7 with good to excellent selectivity. Glucosyl dienes 1 participated as dienophiles in reactions with Schiff bases derived from anilines forming isoquinolines 10 and 11. The diastereoselectivity of this reaction is poor.Fundação para a Ciência e Tecnologia - POCTI/32723/QUI/2000. FEDER

Asymptotic statistics of the n-sided planar Poisson-Voronoi cell. I. Exact results

We achieve a detailed understanding of the $n$-sided planar Poisson-Voronoi cell in the limit of large $n$. Let ${p}\_n$ be the probability for a cell to have $n$ sides. We construct the asymptotic expansion of $\log {p}\_n$ up to terms that vanish as $n\to\infty$. We obtain the statistics of the lengths of the perimeter segments and of the angles between adjoining segments: to leading order as $n\to\infty$, and after appropriate scaling, these become independent random variables whose laws we determine; and to next order in $1/n$ they have nontrivial long range correlations whose expressions we provide. The $n$-sided cell tends towards a circle of radius (n/4\pi\lambda)^{\half}, where $\lambda$ is the cell density; hence Lewis' law for the average area $A\_n$ of the $n$-sided cell behaves as $A\_n \simeq cn/\lambda$ with $c=1/4$. For $n\to\infty$ the cell perimeter, expressed as a function $R(\phi)$ of the polar angle $\phi$, satisfies $d^2 R/d\phi^2 = F(\phi)$, where $F$ is known Gaussian noise; we deduce from it the probability law for the perimeter's long wavelength deviations from circularity. Many other quantities related to the asymptotic cell shape become accessible to calculation.Comment: 54 pages, 3 figure

Atividade da reductase do nitrato em milho (Zea mays L.) var. Piranão em níveis crescentes de nitrogênio.

O objetivo deste trabalho foi estudar a atividade da reductase do nitrato em milho (Zea mays L. var. "Piranao") cultivado em solucao nutritiva e sob doses crescentes de nitrogenio, na forma de NO3. A atividade da enzima foi analisada aos 56 dias de idade, em rodelas de folhas do terco medio da folha +4, seguindo-se a metodologia proposta por MULDER et alii (15), adaptada por MALAVOLTA (13). Os resultados permitiram concluir que o aumento do teor de NO3 no meio favoreceu a atividade da reductase do nitrato ate o nivel maximo de 40,51 ug de N-NO-2/g de materia verde, correspondente a um nivel de 296,19 mg de N/litro de solucao nutritiva. Os resultados obtidos nas condicoes experimentais em que foi realizado o trabalho correspondem, provavelmente, ao maximo da capacidade genetica da variedade estudada. Os teores de N encontrados nas folhas inferiores foram mais baixos do que os das folhas superiores, em funcao da alta mobilizacao do elemento para as partes mais novas da planta. Houve tambem correlacao positiva entre a atividade da reductase do nitrato, o teor de N total da folha e a producao de materia seca

Solving the inhomogeneous Bethe-Salpeter equation

We develop an advanced method of solving homogeneous and inhomogeneous Bethe-Salpeter equations by using the expansion over the complete set of 4-dimensional spherical harmonics. We solve Bethe-Salpeter equations for bound and scattering states of scalar and spinor particles for the case of one meson exchange kernels. Phase shifts calculated for the scalar model are in agreement with the previously published results. We discuss possible manifestations of separability for one meson exchange interaction kernels.Comment: 9 pages, 11 eps-figures. Talk presented by S. S. Semikh at XVII International Baldin Seminar on High Energy Physics Problems "Relativistic Nuclear Physics and Quantum Chromodynamics", September 27 - October 2, 2004, Dubna, Russia; to appear in the proceedings of this conferenc

A predictive score for retinopathy of prematurity in very low birth weight preterm infants

Aims This study describes the development of a score based on cumulative risk factors for the prediction of severe retinopathy of prematurity (ROP) comparing the performance of the score against the birth weight (BW) and gestational age (GA) in order to predict the onset of ROP.Methods A prospective cohort of preterm infants with BWp1500 g and/or GAp32 weeks was studied. the score was developed based on BW, GA, proportional weight gain from birth to the 6th week of life, use of oxygen in mechanical ventilation, and need for blood transfusions from birth to the 6th week of life. the score was established after linear regression, considering the impact of each variable on the occurrences of any stage and severe ROP. Receiver operating characteristic (ROC) curves were used to determine the best sensitivity and specificity values for the score. All variables were entered into an Excel spreadsheet (Microsoft) for practical use by ophthalmologists during screening sessions.Results the sample included 474 patients. the area under the ROC curve for the score was 0.77 and 0.88 to predict any stage and severe ROP, respectively. These values were significantly higher for the score than for BW (0.71) and GA (0.69) when measured separately.Conclusions ROPScore is an excellent index of neonatal risk factors for ROP, which is easy to record and more accurate than BW and GA to predict any stage ROP or severe ROP in preterm infants. the scoring system is simple enough to be routinely used by ophthalmologists during screening examination for detection of ROP. Eye (2012) 26, 400-406; doi: 10.1038/eye. 2011.334; published online 23 December 2011Hosp Clin Porto Alegre, Dept Ophthalmol, BR-90035903 Porto Alegre, RS, BrazilUniv Fed Rio Grande do Sul, Dept Ophthalmol, Sch Med, Porto Alegre, RS, BrazilUniversidade Federal de São Paulo, Dept Ophthalmol, Sch Med, São Paulo, BrazilUniv Fed Rio Grande do Sul, Dept Paediat, Newborn Sect, Sch Med, Porto Alegre, RS, BrazilUniversidade Federal de São Paulo, Dept Ophthalmol, Sch Med, São Paulo, BrazilWeb of Scienc

Enraizamento in vitro de mogno (Swietenia macrophylla King).

O presente trabalho teve como objetivo comparar diferentes concentrações de AIB e ANA para indução do enraizamento de ápices e brotações de mogno (Swietenia macrophylla King) in vitro. Os explantes utilizados foram obtidos de experimentos de multiplicação in vitro com, no mínimo, 2cm de comprimento, com suas bases cortadas de forma transversal. O meio utilizado foi o MS (Murashige & Skoog, 1962), porém adicionado de vitamina do WPM (Mccown & Lloyd, 1981), suplementado com 3% de sacarose, ágar 0,7% e PVP (Polivinilpirrolidona) 0,1%. Foram testados AIB a (0,1; 1,0; 3,0 e 5,0 mgL-1) e ANA a (0,1; 2,0 e 5,0 mgL-1). Os explantes permaneceram por cinco dias nos meios de cultura, em contato com estas auxinas. Após, foram transferidos para meios novos sem os reguladores de crescimento e com os sais do meio MS reduzidos à metade. A auxina ANA na concentração de 2,0 e 5,0 mgL-1foi mais eficiente para indução do enraizamento, com percentual acima de 70%, tanto em ápice quanto em brotações

Role of retardation in 3-D relativistic equations

Equal-time Green's function is used to derive a three-dimensional integral equation from the Bethe-Salpeter equation. The resultant equation, in the absence of anti-particles, is identical to the use of time-ordered diagrams, and has been used within the framework of $\phi^2\sigma$ coupling to study the role of energy dependence and non-locality when the two-body potential is the sum of $\sigma$-exchange and crossed $\sigma$ exchange. The results show that non-locality and energy dependence make a substantial contribution to both the on-shell and off-shell amplitudes.Comment: 17 pages, RevTeX; 8 figures. Accepted for publication in Phys. Rev. C56 (Nov. 97

Social and ethical criteria for prioritizing patients: a survey of students and health professionals in Portugal

O estudo quali-quantitativo explora o dilema ético da microalocação dos recursos da saúde. Objetiva identificar e comparar a opinião de dois grupos da sociedade portuguesa - estudantes e profissionais de saúde sobre a importância das características pessoais dos pacientes no momento de os priorizar e se as escolhas se explicam por referenciais bioéticos de caráter utilitaristas ou deontológicos. Os dados foram recolhidos através de um questionário aplicado a uma amostra de 180 estudantes universitários e 60 profissionais de saúde. Os respondentes perante hipotéticos cená- rios de emergência clínica tiveram de escolher de entre dois pacientes (distinguidos por idade, sexo, responsabilidade social, situação económica e laboral, comportamentos lesivos da saúde e registo criminal) quem tratar e justificar a escolha. Foram usados testes estatísticos de associação para comparar as respostas dos dois grupos e análise de conteúdo para categorizar as justificações. Os resultados sugerem a existência de diferenças nas escolhas dos dois grupos, com os profissionais de saúde a revelarem aceitar menos a utilização de critérios sociais em contexto de escassez e coexistência de critérios utilitaristas e deontológicos, com predomínio da eficiência por parte dos profissionais de saúde e da equidade por parte dos estudantesThis qualitative/quantitative study examines the ethical dilemma of microallocation of health resources. It seeks to identify and compare the opinion of two groups in Portuguese society – students and health professionals – on the importance of personal characteristics of patients at the moment of prioritizing them and if the choices can be explained by bioethical references of a utilitarian or deontological nature. Data were collected by means of a questionnaire administered to a sample of 180 students and 60 health professionals. Faced with hypothetical emergency scenarios, the respondents had to choose between two patients (distinguished by: age, gender, social responsibility, economic and employment situation, harmful health behaviors and criminal record), duly selecting who to treat and then justifying their choice. The results suggest the existence of differences in choices between the two groups, with health professionals revealing they are less prepared to accept the use of social criteria in a context of scarce resources and co-existence of utilitarian and deontological criteria, with a predominance of efficiency on the part of health professionals and equity on the part of students.info:eu-repo/semantics/publishedVersio