El funcionamiento del tributo en Nueva Granada a finales del siglo XVII: Guatavita en 1690 (Estudios)

Este ensayo examina los mecanismos de articulación política que se crearon entre el corregidor y los pueblos de indios que integraron el partido de Guatavita. Analiza la naturaleza y el monto del tributo que pagaron los indios y el manejo que el corregidor hizo de estos recursos. Estudia las cargas fiscales que se impusieron sobre la encomienda y los vínculos políticos que se desarrollaron entre encomenderos, corregidores y Estado colonial. La evidencia histórica que sirve de sustento a este trabajo proviene de la contabilidad que presentó el corregidor de Guatavita ante las autoridades coloniales a finales del siglo XVII.

Modelo de plan estratégico para la gestión de inventarios para los repuestos John Deere de Ponce Yepes S.A.

En el presente trabajo se propone un modelo de plan estratégico, cuya aplicación se sugiere en la empresa Ponce Yepes S.A., con el objetivo de conseguir una eficiente y eficaz gestión de inventarios para la Línea de Repuestos John Deere. El estudio se ha dividido en tres capítulos, en los cuales se van estructurando progresivamente las diferentes etapas para el establecimiento del plan estratégico que se propone. El primer capítulo contiene un resumen teórico sobre la administración de inventarios, los conceptos, la clasificación y los modelos más difundidos. En el segundo capítulo se realiza el análisis de la situación actual de la empresa, enfocado a la Línea de Repuestos John Deere. Este capítulo incluye el análisis del entorno, el esquema de funcionamiento actual del sistema de inventarios, el análisis FODA, la determinación de los clientes internos y externos con sus correspondientes demandas, la elaboración y análisis de las matrices de evaluación de factores internos y externos, en forma individual y combinada; y, se presentan las listas de las estrategias a aplicarse. En el tercer capítulo se presenta la estructuración del plan estratégico, que está compuesto por la reformulación de la misión y visión, el establecimiento de objetivos globales para la gestión de repuestos John Deere, la formulación de las estrategias y políticas para alcanzar dichos objetivos y se concluye detallando el plan operativo, el cual incluye la matriz de aplicación del plan operativo, el cronograma de cumplimiento, el modelo de evaluación y seguimiento de dicho plan, y el flujo de caja del presupuesto de costos. Finalmente se presentan las conclusiones y recomendaciones resultantes del modelo de plan estratégico propuesto.

Dr John Snow and an early investigation of groundwater contamination

John Snow was a physician but his studies of the way in which cholera is spread have long attracted the interest of hydrogeologists. From his investigation into the epidemiology of the cholera outbreak around the well in Broad Street, London, in 1854, Snow gained valuable evidence that cholera is spread by contamination of drinking water. Subsequent research by others showed that the well was contaminated by sewage. The study therefore represents one of the first, if not the first, study of an incident of groundwater contamination in Britain. Although he had no formal geological training, it is clear that Snow had a much better understanding of groundwater than many modern medical practitioners. At the time of the outbreak Snow was continuing his practice as a physician and anaesthetist. His casebooks for 1854 do not even mention cholera. Yet, nearly 150 years later, he is as well known for his work on cholera as for his pioneering work on anaesthesia, and his discoveries are still the subject of controversy.

Electrochemical determination of plant-derived leuco-indigo after chemical reduction by glucose

Electrochemical determination of redox active dye species is demonstrated in indigo samples contaminated with high levels of organic and inorganic impurities. The use of a hydrodynamic electrode system based on a vibrating probe (250 Hz, 200 mu m lateral amplitude) allows time-independent diffusion controlled signals to be enhanced and reliable concentration data to be obtained under steady state conditions at relatively fast scan rates up to 4 V s-1In this work the indigo content of a complex plant-derived indigo sample (dye content typically 30%) is determined after indigo is reduced by addition of glucose in aqueous 0.2 M NaOH. The soluble leuco-indigo is measured by its oxidation response at a vibrating electrode. The vibrating electrode, which consisted of a laterally vibrating 500 mu m diameter gold disc, is calibrated with Fe(CN)(6) 3-/4- in 0.1 M KCl and employed for indigo determination at 55, 65, and 75 C in 0.2 M NaOH. Determinations of the indigo content of 25 different samples of plant-derived indigo are compared with those obtained by conventional spectrophotometry. This comparison suggests a significant improvement by the electrochemical method, which appears to be less sensitive to impurities.

The significance of "nonsignificance" in randomized controlled studies: a discussion inspired by a double-blinded study on St. John's Wort (Hypericum perforatum L.) for premenstrual symptoms

Objectives: This study aimed to investigate the efficacy of St. John's wort extract (SJW) as a treatment for premenstrual symptoms. Design: The study was a randomized, double-blinded, placebo-controlled trial, with two parallel treatment groups. After a no-treatment baseline cycle, volunteers were randomized to either SJW or placebo for a further two menstrual cycles. Settings/location: A postal trial conducted from The University of Reading, Berkshire, England. Subjects: One hundred and sixty-nine (169) normally menstruating women who experienced recurrent premenstrual symptoms were recruited onto the study. One hundred and twenty-five (125) completed the protocol and were included in the analysis. Interventions: Six hundred milligrams (600) mg of SJW (standardized to contain 1800 mug of hypericin) or placebo (containing lactose and cellulose). Outcome measure: A menstrual diary was used to assess changes in premenstrual symptoms. The anxiety-related subgroup of symptoms of this instrument was used as the primary outcome measure. Results: After averaging the effects of treatment over both treatment cycles it was found that there was a trend for SJW to be superior to placebo. However, this finding was not statistically significant. Conclusion: The possibility that this nonsignificant finding resulted from insufficient statistical power in the study, rather than a lack of efficacy of SJW, is discussed. Following this discussion the recommendation is made that, in future, similar studies should be powered to detect a minimum clinically relevant difference between treatments.