Contenido de nitrógeno en grano de trigo y cebada cervecera ante condiciones contrastantes de fuente - destino en post - antesis

Trigo y cebada son cultivos con un alto grado de difusión a nivel mundial. Ambos son importantes como especies cultivables debido a la utilidad que poseen sus granos. El principal destino de trigo es la industria harinera y el de cebada la industria maltera. Estas industrias requieren que el grano posea un porcentaje de proteína determinado. El objetivo general del trabajo fue analizar en forma comparada para trigo y cebada las variaciones en el porcentaje de nitrógeno en el grano ante modificaciones en la relación fuente - destino en post-antesis. Los factores considerados en el análisis fueron (i) un cultivar de trigo y cebada, (ii) dos niveles contrastantes de disponibilidades de nitrógeno en suelo a siembra (57 kg N ha-1, N0; 130 kg N ha-1, N1), (iii) variaciones en la relación fuente - destino (F:D) a lo largo del período de llenado (7, 14, 21 y 28 días desde antesis), dadas por (iii.1) sin modificación en la relación fuente - destino (control), (iii.2) incremento en la disponibilidad de recursos por grano mediante desespiguillado (tratamiento DE), (iii.3) disminución parcial en el tamaño de la fuente foliar actual (defoliación de todas las hojas verdes del cultivo con excepción de la hoja bandera, tratamiento HB), y (iii.4) supresión total en el tamaño de la fuente foliar actual (defoliación de todas las hojas verdes, tratamiento SH). El desespiguillado en trigo aumentó el porcentaje de nitrógeno en grano (PNG) independientemente del momento en el cual se realizó dicho tratamiento, y con mayor efecto en la situación NO que N1. En cebada, solo el tratamiento DE 7 generó incrementos en el PNG respecto al control. Por consiguiente, la limitación por nitrógeno post-antesis fue mayor en trigo que en cebada y se evidenció hasta estados intermedio - avanzados del período de llenado. Los tratamientos de defoliaciones parciales o totales no presentaron diferencias en PNG con respecto a la situación control en ningún momento del periodo de llenado en el que se realizó el tratamiento en ninguno de los cultivares. La respuesta del PNG a los cambios F:D de granos provenientes del vástago principal fue semejante a la de los granos de los macollos.

El estrés térmico post - floración y sus efectos sobre el peso y la calidad de los granos en maíces de diferente destino de producción

En maíz, los golpes de calor (días con temperaturas menor a 35 grados C) ocurridos tempranamente durante el período post-floración pueden afectar negativamente el peso individual de los granos, a traves de limitaciones del crecimiento del cultivo. El conocimiento que existe respecto a las bases eco-fisiológicas de la respuesta de la calidad de los granos a la incidencia de este estres durante el llenado efectivo es prácticamente nulo. El objetivo de este trabajo fue analizar en condiciones a campo el impacto de los golpes de calor durante las etapas tempranas y tardías del llenado efectivo sobre el peso, la calidad general y específica de la industria de los granos en híbridos de maíz de diferente destino de producción (colorado duro o flint, pisingallo y semi-dentad). Los golpes de calor, especialmente aquellos ocurridos durante las etapas tempranas del llenado, redujeron el crecimiento de los cultivos por caídas de la eficiencia en el uso de la radiacion interceptada. Esto produjo un desbalance entre la disponibilidad de asimilados y el requerimiento de estos por parte de los granos que se tradujo en una interrupción prematura del llenado. Consecuentemente, se obtuvieron granos mas livianos con concentraciones mas bajas de aceite y mas altas de proteína. Estas respuestas fueron acompanadas de alteraciones en la composición específica de las proteínas de reserva, incrementándose la abundancia relativa de glutelinas, y ƒÀ- y ƒÁ- zeinas, en detrimento de aquella de ƒ¿-zeinas. Asimismo, los golpes de calor provocaron efectos negativos sobre los diversos parámetros de calidad industrial de los granos, asociados principalmente a disminuciones en la abundancia relativa de ƒ¿-zeínas. Para la mayoría de los rasgos mencionados, los híbridos semi-dentados tuvieron una respuesta mas pronunciada al estrés que los híbridos colorado duro y pisingallo, aparentando ser sensibles a temperaturas del aire incluso inferiores a 35 grados C.

Distributed digital post-production

It is now possible to use powerful general purpose computer architectures to support post-production of both video and multimedia projects. By devising a suitable portable software architecture and using high-speed networking in an appropriate manner, a system has been constructed where editors are no longer tied to a specific location. New types of production, such as multi-threaded interactive video, are supported. Editors may also work remotely where very high speed network connection is not currently provided. An object-oriented database is used for the comprehensive cataloging of material and to support automatic audio/video object migration and replication. Copyright © 1997 by the Society of Motion Picture and Television Engineers, Inc.

A computational study of the characteristics of aircraft post-crash fires

Full-scale furnished cabin fires have been studied experimentally for the purpose of characterising the post-crash cabin fire environment by the US Federal Aviation Administration for many years. In this paper the Computational Fluid Dynamics fire field model SMARTFIRE is used to simulate one of these fires conducted in the C-133 test facility in order to provide further validation of the computational approach and the SMARTFIRE software. The experiment involves exposing the interior cabin materials to an external fuel fire, opening only one exit at the far end of the cabin (the same side as the rupture) for ventilation, and noting the subsequent spread of the external fire to the cabin interior and the onset of flashover at approximately 210 seconds. Through this analysis, the software is shown to be in good agreement with the experimental data, producing reasonable agreement with the fire dynamics prior to flashover and producing a reasonable prediction of the flashover time i.e. 225 seconds. The paper then proceeds to utilize the model to examine the impact on flashover time of the extent of cabin furnishings and cabin ventilation provided by available exits

Predicting the likely impact of aircraft post crash fire on aircraft evacuation using fire and evacuation simulation

The SMARTFIRE Computational Fluid Dynamics (CFD) fire field model has successfully reproduced the observed characteristics including measured temperatures, species concentrations and time to flashover for a post-crash fire experiment conducted by the FAA within their C-133 cabin test facility. In this test only one exit was open in order to provide ventilation for the developing cabin fire. In real post-crash fires, many exits are likely to be open as passangers attempt to evacuate. In this paper, the likely impacts on evacuation of a post-crash fire in which various exiting combinations are available are investigated. The fire scenario, investigated using the SMARTFIRE software, is based on the C-133 experiment but with a fully furnished cabin and with four different exit availability options. The fire data is imported into the airEXODUS evacuation simulation software and the resulting evacuations examined. The combined fire and evacuation analysis reveals that even though the aircraft configuration is predicted to comfortably satisfy the evacuation certification requirement, when fire is included, a number of casualties result, even from the certification compliant exit configuration.

Trust, leadership and economic necessity in post-compulsory education

Trust is a complex concept that has increasingly been debated in academic research (Kramer and Tyler, 1996). Research on 'trust and leadership' (Caldwell and Hayes, 2007) has suggested, unsurprisingly, that leadership behaviours influence 'follower' perceptions of leaders' trustworthiness. The development of 'ethical stewardship' amongst leaders may foster high trust situations (Caldwell, Hayes, Karri and Bernal, 2008), yet studies on the erosion of teacher professionalism in UK post-compulsory education have highlighted the distrust that arguably accompanies 'new managerialism', performativity and surveillance within a climate of economic rationalisation established by recent deterministic skills-focused government agendas for education (Avis, 2003; Codd, 1999, Deem, 2004, DFES, 2006). Given the shift from community to commercialism identified by Collinson and Collinson (2005) in a global economic environment characterised by uncertainty and rapid change, trust is, simultaneously, increasingly important and progressively both more fragile and limited in a post compulsory education sector dominated by skills-based targets and inspection demands. Building on such prior studies, this conference paper reports on the analysis of findings from a 2007-8 funded research study on 'trust and leadership' carried out in post-compulsory education. The research project collected and analysed case study interview and survey data from the lifelong learning sector, including selected tertiary, further and higher education (FE and HE) institutions. We interviewed 18 UK respondents from HE and FE, including principals, middle managers, first line managers, lecturers and researchers, supplementing and cross-checking this with a small number of survey responses (11) on 'trust and leadership' and a larger number (241) of survey responses on more generalised leadership issues in post-compulsory education. A range of facilitators and enablers of trust and their relationship to leadership were identified and investigated. The research analysed the ways in which interviewees defined the concept of 'trust' and the extent to which they identified that trust was a mediating factor affecting leadership and organisational performance. Prior literature indicates that trust involves a psychological state in which, despite dependency, risk and vulnerability, trustors have some degree of confident expectation that trustees will behave in benevolent rather than detrimental ways. The project confirmed the views of prior researchers (Mayer, Davis and Schoorman, 1995) that, since trust inevitably involves potential betrayal, estimations of leadership 'trustworthiness' are based on followers' cognitive and affective perceptions of the reliability, competence, benevolence and reputation of leaders. During the course of the interviews it also became clear that some interviewees were being managed in more or less transaction-focused, performative, audit-dominated cultures in which trust was not regarded as particularly important: while 'cautious trust' existed, collegiality flourished only marginally in small teams. Economic necessity and survival were key factors influencing leadership and employee behaviours, while an increasing distance was reported between senior managers and their staff. The paper reflects on the nature of the public sector leadership and management environment in post-compulsory education reported by interviewees and survey respondents. Leadership behaviours to build trust are recommended, including effective communication, honesty, integrity, authenticity, reliability and openness. It was generally felt that building trust was difficult in an educational environment largely determined by economic necessity and performativity. Yet, despite this, the researchers did identify a number of examples of high trust leadership situations that are worthy of emulation.