982 resultados para Popper, Karl R.(Karl Raimund), 1902-1994


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EXTRACT (SEE PDF FOR FULL ABSTRACT): The influence of ENSO on atmospheric circulation and precipitation over the western United States is presented from two perspectives. First, ENSO-associated circulation patterns over the North Pacific/North America sector were identified using an REOF (rotated empirical orthogonal function) analysis of the 700-mb height field and compositing these for extreme phases of the Southern Oscillation Index. ... Second, we examine the variability of precipitation during the warm and cool phases of ENSO for different locations in the western United States.

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The gut content of Nemipterus japonicus revealed that this fish is a carnivorous bottom feeder, feeding mainly on crustaceans, fishes, salps and polychaetes, with marginal variations in females. The intensity of feeding increased with the advancement of maturity till stage 5 except in stage 3 where the intensity of feeding indicated a decrease.

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Quantitative assays of trypsin, amylase and alkaline phosphatases were made in relation to age and food during the larval development of the Indian major carp Catla catla. The responses of all the test enzymes to age and food were identical. No enzymes were detected from the fertilized eggs. Detectable amount of enzymes were first observed in the first day old hatchlings. All the test enzymes in the group fed normal feed tended to rise gradually with advancement of age till day 22 after which an asymptotic level was attained. Absence of food throughout the rearing period caused the enzymatic activity of the larva to remain at the lowest level throughout. When starvation was followed by feeding, enzymatic activity in the former group was consistently higher than that of latter, suggesting that feeding activity was primarily responsible in maintaining the enzymatic activity of carp larva. The enzymatic activity of zooplankton was significantly higher than carp larva till day 6 to 12 after which the latter exceeded the former implying that carp larva during development utilizes the exogenous enzymes of zooplankton.

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An enhanced physical model of the bowed string presented previously [1] is explored. It takes into account: the width of the bow, the angular motion of the string, bow-hair elasticity and string bending stiffness. The results of an analytical investigation of a model system - an infinite string sticking to a bow of finite width and driven on one side of the bow - are compared with experimental results published by Cremer [2] and reinterpreted here. Comparison shows that both the width of the bow and the bow-hair elasticity have a large impact on the reflection and transmission behaviour. In general, bending stiffness plays a minor role. Furthermore, a method of numerical simulation of the stiff string bowed with a bow of finite width is presented along with some preliminary results.

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The kinetics of the photomineralization of salicylic acid (SA) sensitized by Degussa P25 titanium dioxide (TiO2) dispersions in oxygenated aqueous solution are reported as a function of the following experimental parameters: [TiO2], percentage of O-2, [SA], temperature (T) and light intensity (I). The kinetics of SA photomineralization conform to a Langmuir-Hinshelwood kinetic scheme with SA and O-2 adsorbed at different sites with apparent Langmuir adsorption coefficients of (6.1 +/- 1.2) x 10(4) mol(-1) dm(3) and 0.061 +/- 0.007 kPa(-1) respectively. The overall activation energy for the system was determined as 4.6 +/- 0.2 kJ mol(-1). Two major stable reaction intermediates are identified (dihydroxybenzoic acids (DHBA) and catechol (C)) and the existence of a further pathway involving one or more very unstable and, as yet, unidentified reaction intermediates is proposed. A kinetic model is presented which describes the temporal behaviour of the concentrations of SA, CO2 and the major photogenerated intermediates (DHBA and C). This model is used to predict successfully the temporal behaviour of the major intermediates in the photomineralization of SA under non-standard conditions.

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In this paper we employ Erikson and Goldthorpe's core model of social fluidity and a 'measured variable' approach to analyse trends in social mobility among men in the Republic of Ireland. Our analyses provide no evidence that the changes associated with industrialization have led to the increases in social fluidity predicted by the liberal theory of industrialism. The measured-variable approach we employ consistently provides a better fit to the Irish data than the core model. The application of the former model points to a degree of importance of the hierarchy dimension which is not captured adequately by the core model. It also suggests that the well-known distinctiveness of the Irish social mobility regime is open to explanation in terms of general dimensions rather than the peculiarities of the Irish case.

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As Laver (1992) notes, people who write about Irish politics frequently describe Ireland as a rather peculiar place. One aspect of this peculiarity is that voters in the Republic of Ireland do not behave like their European counterparts. In particular, Irish voting patterns appear to be only weakly structured by social class. Recent contributions to the debate employing a more sophisticated categorisation of classes have led to some qualification of the 'politics without social bases' description, but still lead to the broad conclusion that any relationship which does exist between social divisions, on the one hand, and party preference, on the other, is, at most, quite marginal. In this paper we draw on data from the 1990 European Values Study to re-examine this issue. We apply a variety of models to the data, including logit regression and diagonal reference models (Sobel 1981, 1984) to explore the complex fashion in which class and political preferences are related in Ireland. We argue that the relationship between such preferences and social divisions are, in fact, greater than has been hitherto thought. In particular, we show the importance of taking into account not only social class but also class origins and class mobility in understanding the nature of political partisanship in the Republic of Ireland.

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The Maillard or browning reaction between sugar and protein contributes to the increased chemical modification and cross-linking of long-lived tissue proteins in diabetes. To evaluate the role of glycation and oxidation in these reactions, we have studied the effects of oxidative and antioxidative conditions and various types of inhibitors on the reaction of glucose with rat tail tendon collagen in phosphate buffer at physiological pH and temperature. The chemical modifications of collagen that were measured included fructoselysine, the glycoxidation products N epsilon-(carboxymethyl)lysine and pentosidine and fluorescence. Collagen cross-linking was evaluated by analysis of cyanogen bromide peptides using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and by changes in collagen solubilization on treatment with pepsin or sodium dodecylsulfate. Although glycation was unaffected, formation of glycoxidation products and cross-linking of collagen were inhibited by antioxidative conditions. The kinetics of formation of glycoxidation products proceeded with a short lag phase and were independent of the amount of Amadori adduct on the protein, suggesting that autoxidative degradation of glucose was a major contributor to glycoxidation and cross-linking reactions. Chelators, sulfhydryl compounds, antioxidants, and aminoguanidine also inhibited formation of glycoxidation products, generation of fluorescence, and cross-linking of collagen without significant effect on the extent of glycation of the protein. We conclude that autoxidation of glucose or Amadori compounds on protein plays a major role in the formation of glycoxidation products and cross-liking of collagen by glucose in vitro and that chelators, sulfhydryl compounds, antioxidants, and aminoguanidine act as uncouplers of glycation from subsequent glycoxidation and cross-linking reactions.

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PURPOSE: The authors investigated the receptor-mediated endocytosis (RME) and intracellular trafficking of insulin and low-density lipoprotein (LDL) in cultured retinal vascular endothelial cells (RVECs). METHODS: Low-density lipoprotein and insulin were conjugated to 10 nm colloidal gold, and these ligands were added to cultured bovine RVECs for 20 minutes at 4 degrees C. The cultures were then warmed to 37 degrees C and fixed after incubation times between 30 seconds and 1 hour. Control cells were incubated with unconjugated gold colloid at times and concentrations similar to those of the ligands. Additional control cells were exposed to several concentrations of anti-insulin receptor antibody or a saturating solution of unconjugated insulin before incubation with gold insulin. RESULTS: Using transmission electron microscopy, insulin gold and LDL gold were both observed at various stages of RME. Insulin-gold particles were first seen to bind to the apical plasma membrane (PM) before clustering in clathrin-coated pits and internalization in coated vesicles. Gold was later visualized in uncoated cytoplasmic vesicles, corresponding to early endosomes and multivesicular bodies (MVBs) or late endosomes. In several instances, localized regions of the limiting membrane of the MVBs appeared coated, a feature of endosomal membranes not previously described. After RME at the apical PM and passage through the endosomal system, the greater part of both insulin- and LDL-gold conjugates was seen to accumulate in large lysosome-like compartments. However, a small but significant proportion of the internalized ligands was transcytosed and released as discrete membrane-associated quanta at the basal cell surface. The uptake of LDL gold was greatly increased in highly vacuolated, late-passage RVECs. In controls, anti-insulin receptor antibody and excess unconjugated insulin caused up to 89% inhibition in gold-insulin binding and internalization. CONCLUSION: These results illustrate the internalization and intracellular trafficking by RVECs of insulin and LDL through highly efficient RME, and they provide evidence for at least two possible fates for the endocytosed ligands. This study outlines a route by which vital macromolecules may cross the inner blood-retinal barrier.

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This paper proposes a multicast implementation based on adaptive routing with anticipated calculation. Three different cost measures for a point-to-multipoint connection: bandwidth cost, connection establishment cost and switching cost can be considered. The application of the method based on pre-evaluated routing tables makes possible the reduction of bandwidth cost and connection establishment cost individually

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Estudiar las conductas relacionadas con la salud entre los escolares de la Región de Murcia. Este estudio formó parte de un acuerdo de colaboración suscrito entre la Dirección General de Salud y Consumo y la Dirección Provincial del MEC en Murcia. 2397 escolares (48 varones y 52 mujeres) de 102 centros educativos de la Región de sexto y octavo de EGB, segundo y cuarto de ESO, segundo de BUP y segundo de FPI, entre los 11 y los 15 años de edad. Adaptación del Cuestionario sobre conductas de los escolares españoles relacionadas con la salud de Mendoza, R.; Sagrera, M.R.; Batista, J.M. (1994) a la Región. Selección de la muestra y recogida de datos. Tratamiento y conclusiones. Cuestionario sobre distintos aspectos relacionados con la salud. La publicación ofrece un resumen de los resultados sin especificar la técnica empleada en el tratamiento de los datos. 1. Los jóvenes murcianos practican deporte con más frecuencia que los españoles en general; 2. El porcentaje de jóvenes que han probado el tabaco es elevado aunque menor que en el resto del Estado, igual pasa con el alcohol; 3. Los españoles declaran estar muy sanos en mayor proporción que los murcianos; 4. Por el contrario, los hábitos higiénicos de los escolares murcianos son bastante mejorables con respecto a los datos nacionales; 5. Los hábitos alimenticios son también mejorables en lo que respecta al consumo de fruta, verdura y hortalizas; 6. Más del 40 por ciento de los escolares murcianos tienen problemas de comunicación con el padre y más del 20 con su madre; 7. Casi el 40 por ciento dedica más de dos horas diarias a ver TV; 8. La Educación para la salud presentaba un grado de implantación bajo en los centros educativos de nuestra Comunidad; 9. El consumo de drogas ilegales es relativamente bajo (inferior que en el resto del Estado); 10. Es necesario insistir en las intervenciones educativas para conseguir una reducción aún mayor en la frecuencia de prácticas sexuales de riesgo en los adolescentes. Los centros educativos tienen un papel fundamental que cumplir en la mejora de la salud de la población. Si el proceso educativo pretende preparar a los alumnos de forma integral, para desenvolverse en el medio social y hacer frente a sus exigencias, debe incluir la Educación para la Salud entre sus objetivos. La LOGSE así lo recoge y prescribe que la Educación para la Salud sea incluida como tema trasversal en los distintos niveles de concrección curricular.

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O presente estudo propõe-se verificar a influência das Atitudes e da Ansiedade Face à Morte na Imortalidade Simbólica em estudantes universitários. Procura igualmente perceber quais as relações entre as diferentes variáveis. Com este propósito, foram aplicadas as versões portuguesas do Death Attitude Profile Revised (DAP-R; Wong, Reker, & Gesser, 1994), da Death Anxiety Scale (DAS; Templer, 1970) e da The Sense of Symbolic Immortality Scale (SSIS; Drolet, 1990), juntamente com um Questionário de dados sociodemográficos. Participaram no estudo 310 estudantes universitários de 1º e 2º ciclo, com idades compreendidas entre os 18 e os 56 anos. Os resultados mostram que os estudantes obtêm valores superiores de aceitação neutra e inferiores de aceitação de escape. Relativamente à idade os indivíduos mais velhos apresentam valores superiores de medo e de evitamento da morte, assim como valores inferiores de desejo de imortalidade simbólica. Os homens apresentam resultados mais elevados de aceitação neutra, de escape, de ansiedade face à morte e de desejo de imortalidade simbólica. Constata-se que as atitudes negativas perante a morte e a imortalidade simbólica se correlacionam negativamente com a ansiedade. Os resultados encontrados corroboram a tese de que existe influência das atitudes e da ansiedade no desejo de imortalidade simbólica.