607 research outputs found

    Fructokinase from rat liver. I. Purification and properties

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    Fructokinase (ATP:d-fructose-1-phosphate transferase, EC 2.7.1.3) from rat liver has been purified 400-fold. The purification procedure involves an acid treatment, a heat step at 65°, (NH4)2SO4 fractionation, chromatography on Sephadex G-100 and finally (NH4)2SO4 extraction. The enzyme appears nearly homogenous by density gradient centrifugation but gives a single peak in sedimentation velocity analysis. Purified liver fructokinase has a Km of 0.46-0.80 mM for fructose and 1.56-1.33 mM for MgATP at a K+ concentration of 0.4 and 0.1 M, respectively. The enzyme also phosphorylates l-sorbose and d-tagatose. No difference could be found in the phosphorylation of the pyranose and furanose forms of fructose. The enzyme is inhibited by p-chloromercuribenzoate and is stable up to 50-55°. © 1971.Fil:González, N.S. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Pontis, H.G. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

    Femtosecond XUV induced dynamics of the methyl iodide cation

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    Ultrashort XUV wavelength-selected pulses obtained with high harmonic generation are used to study the dynamics of molecular cations with state-to-state resolution. We demonstrate this by XUV pump - IR probe experiments on CH3I+ cations and identify both resonant and non-resonant dynamics

    Wood anatomy and tree growth covary in riparian ash forests along climatic and ecological gradients

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    Riparian ash forests subjected to seasonal drought are among the most endangered ecosystems in Europe. They are threatened by climate warming causing aridification and by land-use changes modifying river flow. To assess the impacts of these two stress factors on riparian forests, we studied radial growth and xylem anatomical traits in five narrow-leaved ash (Fraxinus angustifolia) stands across wide climatic and ecological gradients from northern Italy to southern Portugal. Radial growth rates and earlywood hydraulic diameter (Dh) were directly correlated, whilst earlywood vessel density and growth rates were inversely associated. Ash growth positively responded to precipitation. Higher and lower rates of growth increase in response to precipitation were found in dry (annual precipitation 357–750 mm, annual water balance -39 to -48 mm) and wet (annual precipitation 1030 mm, annual water balance 27 mm) sites, respectively. Wet conditions in autumn and winter of the year prior to tree-ring formation lead to larger Dh values, except in the wet site where warmer conditions from prior autumn to current spring were positively associated to wider vessels. Growth was also enhanced by a higher river flow, reflecting higher soil moisture due to elevated groundwater table levels. Peaks in river flow from late winter to early spring increased Dh in dry-continental sites. Growth and potential hydraulic conductivity in drought-prone riparian ash forests are differently impacted by climate variability and river flow depending on site and hydrological conditions. Nevertheless, covariation between radial growth and the earlywood vessel diameter was found, regardless of site specific differences. Wood production and hydraulic conductivity are coordinated through the production of large earlywood vessels which may allow reaching higher growth rates. © 2021 The Author

    Incidencia de tuberculosis osteoarticular en el área sanitaria del Hospital de León. 1997-2001

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    Introducción y objetivos: Nos proponemos en este trabajo estudiar la incidencia de tuberculosis en su forma osteoarticular en el área sanitaria del Hospital de León durante los años 1997 a 2001, ambos inclusive. Material y método: Dieciséis casos de tuberculosis osteoarticular confirmados por cultivo microbiológico y/o análisis anatomopatológico fueron incluidos. De ellos, cinco afectaron a columna vertebral, cuatro a rodilla y el resto a otras localizaciones más inusuales. Resultados: De las cinco columnas vertebrales afectadas, tres requirieron tratamiento quirúrgico para descomprimir y estabilizar. En una rodilla se realizó sinovectomía abierta y en otra por artroscopia. Se drenaron abscesos fríos en diferentes localizaciones. Todos los casos recibieron tratamiento médico. Se reflejan los diferentes resultados, desde la restitución ad integrum hasta la anquilosis. Discusión y conclusiones: La incidencia de tuberculosis osteoarticular en nuestra área sanitaria en el periodo 1997-2001 fue del 2% al 4% de todos los cascos de tuberculosis. Hubo una alta incidencia de localizaciones inusuales (muñeca, codo, sacroilíaca).Introduction: Current issue is to study the incidence of osteoarticular tuberculosis, within the sanitary area of the Hospital of Leon. Material and Method: Sixteen cases of osteoarticular tuberculosis confirmed by culture and pathological analysis were included. Five of them involved the raquis and knee. Another cases in unusual local sites. Results: Three of five raquis were managed by decompression and stabilization. One knee was treated by open synovectomy and another one by arthroscopy synovectomy. Cold abscesses were drained in different sites. All cases were treated with drugs. Different results are showed since restitutio ad integrum to anquilosis. Discussion: Osteoarticular tuberculosis incidence in our sanitary area between 1997 to 2001 was 2% to 4%. There was a high incidence for unusual localizations (wrist, elbow and sacroiliaca joints)

    OTELO survey: Deep BVRI broad-band photometry of the Groth strip

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    Context. The Groth field is one of the sky regions that will be targeted by the OTELO (OSIRIS Tunable Filter Emission Line Object) survey in the optical 820 nm and 920 nm atmospheric windows. A complementary broad-band photometric catalogue of the field is essential for several purposes, in particular the inequivocal identification of sources, photometric redshift estimation, and population synthesis fitting.Aims. We aim to describe the OTELO survey and present deep BVRI imaging data of the Groth field. Galaxy number counts, colour distributions and galaxy clustering are analysed.Methods. BVRI deep images (?8 ks) were obtained with the Prime Focus Camera at the WHT (La Palma) and reduced with the IRAF package. The extraction and photometry of the sources was done with SExtractor software. We analysed the final catalogue to obtain galaxy number counts, as well as galaxy correlation functions as a function of I magnitude and V - I colour. It is also compared with estimations from mock catalogues of the Virgo-Millenium consortium.Results. We find excellent agreement between observed and mock data number counts. We also find evidence of galaxy clustering evolution and strong dependence of the angular correlation function on the V - I observed colour. Our data favour a flattening of the clustering amplitude with median apparent magnitude. The good general agreement between our clustering analysis and the estimates from the mock data is remarkableAcknowledgements. This work was supported by the Spanish Plan Nacional de Astronomía y Astrofísica under grants AYA2005–04149 and AYA2006–2358. We thank the referee for helpful comments that improved the clarity of this paper. The Millennium Simulation databases used in this paper and the web application providing online access to them were constructed as part of the activities of the German Astrophysical Virtual Observatory. IRAF is distributed by the National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy (AURA) under cooperative agreement with the National Science Foundation. This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation

    Mechanistic studies on the: N -alkylation of amines with alcohols catalysed by iridium(i) complexes with functionalised N-heterocyclic carbene ligands

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    Iridium(i) cyclooctadiene complexes featuring O- and N-donor functionalised NHC ligands efficiently catalyse the C-N coupling of amines with alcohols through a borrowing hydrogen mechanism. These catalysts have been applied for the N-alkylation of several aromatic and aliphatic primary amines with a range of alcohols including benzyl alcohol derivatives, straight-chain primary alcohols and secondary alcohols. The cationic complex [Ir(NCCH3)(cod){MeIm(2-methoxybenzyl)}]+ (cod = 1, 5-cyclooctadiene, MeIm = 3-methylimidazol-2-ylidene) having a rigid O-donor wingtip exhibits the best catalytic performance for the N-alkylation of aniline with benzyl alcohol giving a quantitative conversion to N-benzylaniline in 3 h. Experimental and theoretical studies at the DFT level on the N-alkylation of aniline with benzyl alcohol catalysed by the model compound [IrCl(cod)(IMe)] (IMe = 1, 3-dimethyl-imidazol-2-ylidene) support the participation of the iridium catalyst not only in the alcohol dehydrogenation and imine hydrogenation steps but also in the key step leading to the formation of the new C-N bond. Nucleophilic attack of an iridium-amido species generated in basic medium on the electrophilic aldehyde results in a hemiaminolate intermediate species from which the hemiaminal is released by alcoholysis. The free hemiaminal dehydrates to give the corresponding intermediate imine product that is hydrogenated by the iridium catalyst to the N-alkylated amine product. The iridium(i) complexes featuring functionalised NHC ligands are more active than [IrCl(cod)(IMe)] which highlights the positive influence of the functional group on the N-alkylation catalytic activity

    Nuestra experiencia con el minivástago femoral de disco a compresión y el cotilo Hedrocel (tantalio)

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    Durante los años 2000 a 2002 intervinimos 18 pacientes de artrosis o necrosis sintomática de cadera, con minivástago de fijación metafisiaria de Disco a Compresión (Sulzer) y cotilo monobloque de tantalio Hedrocel (Zimmer), con par de fricción alúmina-polietileno. La edad media de los pacientes fue de 46,7 años (rango 35-61), y el seguimiento medio de 42 meses. La valoración clínica se realizó con la escala de Merle D'Augbigné Postel obteniendo 38,8% de resultados excelentes, 22,2 de resultados buenos, 11,1% regulares y 27,4% malos (5 casos). Cuatro casos necesitaron reintervención por aflojamiento del tallo femoral. No hubo ningún fracaso del cotilo. La sustitución protésica de la cadera en los pacientes jóvenes requieren soluciones con la menor resección del hueso, pero este modelo de tallo femoral, no da un resultado satisfactorio, por lo que lo hemos abandonado.Between 2000 2002 we treated 18 patients with symptomatic osteoarthritis or osteonechrosis of hip, with uncemneted Thrust Plate Protesis (Sulzer) and tantalium acetabular componente Hedrocel (Zimmer), with ceramic-pol- yethylene pair. The average age of the patients was 46,7 years (range:35-61), and the average follow-up of 42 months. Clinical evaluation was done with Merle D'Augbigné Postel's scale obtaining 38,8 % of excellent results, 22,2 % of good results, 11,1 % fair and 27,4 % poor (5 cases). Four cases needed re-operation for loosening of the femoral stem. There was no failure of the acetabular component. The hip artrhroplasty in the young patients need solutions with the minor resection of bone, but this model of femoral stem does not give a satisfactory result, therefore we have abandoned it

    Perfil del profesorado universitario que emplea un enfoque docente centrado en el alumnado

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    Los enfoques de enseñanza a los que recurren los docentes universitarios determinan su forma de afrontar el proceso educativo y su figura como docentes. Éstos pueden ser de dos tipos, centrado en el profesorado/transmisión de la información y centrado en el alumnado/cambio conceptual. El objetivo de esta investigación es dibujar el perfil del profesor universitario según el enfoque docente más empleado. Con este fin, se aplicó el cuestionario ATI (2004) a un total de 501 docentes universitarios de la Región de Murcia. Los resultados muestran que el enfoque centrado en el alumnado es el más empleado entre las profesoras que han recibido formación didáctica, de menor edad o años de experiencia, preferiblemente de la rama de arte o humanidades y ciencias sociales y jurídicas y dependiendo del tipo de universidad a la que pertenece. De este modo, es posible detectar las variables que determinan el uso de este enfoque, en detrimento del anterior, y como consecuencia, las áreas donde es más necesario trabajar para hacer posible el cambio. The teaching approaches that university teachers use determine their way of facing the educational process and their role as teachers. These can be of two types, Information Transmission/Teacher-focused (ITTF) and Conceptual Change/Student-focused (CCSF). The objective of this research is to draw the profile of the university teacher according to the most employed teaching approach. To this end, the ATI questionnaire (2004) was applied to a total of 501 university teachers from the Region of Murcia. The results show that the student-centered approach is the most used among teachers who have received didactic training, that are younger or with less years of experience, preferably from the art or humanities and social and legal sciences fields and depending on the type of university they belong to. In this way, it is possible to detect the variables that determine the use of this approach, to the detriment of the previous one, and as a consequence, the areas where it is most necessary to work in order to make the change possible

    Motivación y burnout en profesores de educación física: incidencia de la frustración de las necesidades psicológicas básicas

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    A través del presente trabajo se pretende valorar la importanciade las necesidades psicológicas básicas para explicar y predecir el tipo demotivación y los niveles de burnout en profesores de educación física. Paraello, la muestra estuvo formada por 357 docentes de género masculino yfemenino, pertenecientes a diferentes centros educativos públicos y privadosde España. Se realizó un análisis de regresión lineal por cada variabledependiente, que indicaron cómo la frustración de la necesidad de competenciapredecía positivamente la desmotivación, el agotamiento emocionaly el cinismo, y negativamente la motivación intrínseca y la eficacia profesional;la frustración de autonomía predecía positivamente el agotamientosemocional y negativamente la eficacia profesional; y la frustración de relacionessociales predecía positivamente la eficacia profesional. Estos resultadosestán en la línea de la Teoría de la Autodeterminación (Deci y Ryan,2000; Ryan y Deci, 2000), destacando la importancia que adquieren lasatisfacción de autonomía, competencia y relaciones sociales para optimizarla motivación y el bienestar de los profesores de educación física

    Adaptación y validación de un cuestionario para valorar la motivación en el contexto deportivo

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    El objetivo de este estudio era adaptar y validar al contexto deportivo el Cuestionario de Motivación en Educación Física (CMEF), basado en la Teoría de la Autodeterminación (Deci y Ryan, 1985; 2000; Ryan y Deci, 2000) y desarrollado originalmente en el ámbito educativo, para tratar de analizar la motivación intrínseca, identificada, introyectada, externa y desmotivación de los adolescentes. Para ello, participaron un total de 985 deportistas con edades comprendidas entre los 10 y 16 años (M = 14.34; DT = 2.52), de género masculino y femenino pertenecientes a 24 modalidades deportivas diferentes. Los resultados obtenidos demostraron que la escala con cinco factores correlacionados presentaba una adecuada validez factorial a partir de los índices de ajuste obtenidos, registró relaciones positivas entre los motivos de práctica más autodeterminados y relaciones negativas con la desmotivación, que oscilaron de entre -,21 a ,74. Además, se obtuvieron valores aceptables de consistencia interna (Ω > .70) y resultó invariante en función del género, considerando las mínimas modificaciones sufridas en ΔCFI. Asimismo, la validez discriminante de los factores resultó satisfactoria. Por tanto, este estudio aporta una nueva herramienta que permite analizar los tipos de regulación motivacional que impulsan a los adolescentes a realizar una práctica deportiva
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