Analytical and structural studies of plant polysaccharides

The studies presented in this thesis fall into three distinct groups.a) Analytical characterizations have been made of the gum exudates, not hitherto investigated, from 3 species of the genus Parkia, 6 species of the genus Grevillea, 9 species of the Series Phyllodineae and Gummiferae of the genus Acacia, and 15 specimens of gum obtained from Acacia karroo growing in different locations in Africa. Several of the new species of gum have exceptional features e.g. the intrinsic viscosities of the gums from Grevillea caahlabroides and Grevillea wickhamii (521 and 575 nlg⁻¹ respectively) and the nitrogen content (7.5%) of A. dictyophleba gum are the highest values reported to date for these parameters in plant gums.b) A study of some of the structural features of Acacia xanthophloea gum by Smith-degradation, methylation and acid hydrolysis showed the complex acid heteropolysaccharide to be based on a highly-branched ß - 1,3 - linked galactose framework which also contained some ß - 1,6 - linkages. Glucuronic acid and rhamnose were present as end-groups; arabinose was present in short side-chains, up to three units long, attached to the branched galactan core.c) The applicability of natural abundance carbon - 13 nuclear magnetic resonance spectroscopy to structural studies of complex acid heteropolysaccharides of high molecular weight was evaluated by examining the sequence of progressively simpler spectra given by the whole gum and its different degradation products.A preliminary study of the applicability of proton magnetic resonance spectra to complex gum molecules showed that an indication of the amounts of different sugar components present and a rapid non -destructive evaluation of the degree of structural similarity of different gum samples can be obtained

From disappearing narrators to signs of the author: images of the subject in the short stories of Silvina Ocampo

Ph.D. University of Kansas, Spanish and Portuguese 2002This study proposes an in-depth study of subjectivity in Silvina Ocampo's short stories. In the first chapter of this study, I investigate the mechanisms by which self-generation paradoxically elicits the disappearance of the subject while the process of narration encounters repetition, coincidence, and cyclical movement. In these stories typical of the fantastic mode, we also observe the relinquishing of the narrating self's sense of physical and psychological density, a transformation that involves a radically changed as well as a muted, silenced self. A similar investigation of the problems of subjectivity continues in chapter two. This time, however, the focus is on the confrontation between the bourgeois, stable subject and the unstable, mutable subject. Though the bourgeois subject aligned with civilization presupposes a stable, discrete identify, while the barbaric other connotes a destabilized, irrational self, the semantic fields of the two poles, civilization and barbarism, overlap in Ocampo's stories. While undoing traditional dualisms, the physically and psychologically destabilized self challenges the social order, the public and private spaces of bourgeois life, and the relations of power specific to these spaces. A fluid and imprecise form of subjectivity also emerges in Ocampo's introspective work that investigates, while achieving in the process, the creation of authorial self. The contours of an authorial consciousness come into view in the interplay of the fictive metaphors of gestation, the elusive or lost masterpiece, mirrors, and the photograph. The recurring themes and images generated by these metaphors reveal signs of an authorial persona preoccupied with the complex properties of selfhood and reality and the pitfalls in their representations, as well as with the relation between the creator and her literary world

Lagrangian-Hamiltonian unified formalism for field theory

The Rusk-Skinner formalism was developed in order to give a geometrical unified formalism for describing mechanical systems. It incorporates all the characteristics of Lagrangian and Hamiltonian descriptions of these systems (including dynamical equations and solutions, constraints, Legendre map, evolution operators, equivalence, etc.). In this work we extend this unified framework to first-order classical field theories, and show how this description comprises the main features of the Lagrangian and Hamiltonian formalisms, both for the regular and singular cases. This formulation is a first step toward further applications in optimal control theory for PDE's.Comment: LaTeX file, 23 pages. Minor changes have been made. References are update

Por el Dean y Cabildo de la Santa Iglesia de Sevilla, como patrono de las obras pias, que fundo Gaspar de Leon Garavito, en el pleyto con el R. P. M. Fr. Domingo de Molina patrono del patronato que fundó (pagadas sus deudas y legados) Doña Ana Pizarro .

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Por D. Roque de S. Miguel y Albear , presbitero, beneficiado de la Iglesia parrochial de San Juna de la Palma, y Doña Maria Josepha de Leon y Cordoba, viuda y albacea con el dicho don Roque, de Don Pedro de San Miguel y Albear Mayordomo que fue de la Mes

A 109/123(05

Hacia una historia de la agroecología en Colombia

This document provides a brief description of some individuals, institutions and processes that were developed in Colombia around agro-ecology, understood in a broad concept, since the late 80s of the twentieth century, as a contribution to the understanding of the history of their concept and practice in the central, west and east regions of the country, highlighting the contributions made by academics, NGOs, universities, peasant farmers, environmental activists, enterprises and producers.Este documento presenta una breve descripción de algunas personas, instituciones y procesos que se desarrollaron en Colombia alrededor de la agroecología, entendida en un amplio concep- to, desde finales de los años 80 del siglo XX, como un aporte para la comprensión de la historia de su concepción y práctica en el centro, occidente y oriente del país, resaltando los aportes realizados por académicos, organizaciones no gubernamentales, universidades, agricultores campesinos, activistas ambientales y gremios de la producción