Remarks on the Monge-Ampère equation: some free boundary problems in geometry

This paper deals with several qualitative properties of solutions of some stationary and parabolic equations associated to the Monge-Ampère operator. Mainly, we focus our attention in the occurrence of a free boundary (separating the region where the solution u is locally a hyperplane, and so were the Hessian D2u is vanishing from the rest of the domain). Among other thinfs, we take advantage of these proceedings to give a detailed version of some results already announced long time ago when dealing wiht other fully nonlinear equations (see the 1979 àèr by the authors on other parabolic equations, remark 2.25 of the 1985 monograph by the second author and the 1985 paper by the first author. In particular, our results apply to suitable formulations of the Gauss curvature flow and of the worn stones problems intensively studied in the literature

On an evolution problem associated to the modelling of incertitude into the environment

We consider a mathematical model, posed by J.E. Scheinkman, simulating that an industrial project takes place into the environment without destroying it. We introduce a change of variable leading the formulation to a nonlinear evolution problem which we study by means of L-infinity-accretive operator techniques. We prove that under suitable conditions there is extinction in finite time, which corresponds to some special behaviour of the solution of the original stochastic control problem

Climate Change Impacts on Maize and Dry Bean Yields of smallholder farmers in Honduras

The rotation maize and dry bean provides the main food supply of smallholder farmers in Honduras. Crop model assessment of climate change impacts (2070?2099 compared to a 1961?1990 baseline) on a maize?dry bean rotation for several sites across a range of climatic zones and elevations in Honduras. Low productivity systems, together with an uncertain future climate, pose a high level of risk for food security. The cropping systems simulation dynamic model CropSyst was calibrated and validated upon field trail site at Zamorano, then run with baseline and future climate scenarios based upon general circulation models (GCM) and the ClimGen synthetic daily weather generator. Results indicate large uncertainty in crop production from various GCM simulations and future emissions scenarios, but generally reduced yields at low elevations by 0 % to 22 % in suitable areas for crop production and increased yield at the cooler, on the hillsides, where farming needs to reduce soil erosion with conservation techniques. Further studies are needed to investigate strategies to reduce impacts and to explore adaptation tactics

An experimental research programme on heterogeneous combustion processes under microgravity conditions. Preliminary results

In the present work preliminary results are given of an experimental programme on flame spreading over the surface of PMMA rods in NgO2 mixtures under microgravity conditions. Results were obtained in the NASA KC-135 aircraft laboratory. Six experiments were carried out in March of this year and 36 more experiments will be conducted in March 1987. These preliminary experiments allowed to determine the flame spreading velocities for three different mixture compositions, showing that they were smaller but of the same order of magnitude than downwards spreading velocities at one g and for the same mixture condition

An Experimental Programme on Flame Spreading at Reduced Gravity Conditions.

An experimental programme on flame spreading over the surface of polymethylmetacrylate (PMMA) samples has been conducted at reduced gravity conditions in the NASA KC-135 air craft laboratory. A total of 36 experiments were performed. From the results of these experiments the flame spreading velocities over PMMA samples have been obtained, as well as their laws of variation with pressure and mixture composition. Both cylindrical and flat samples have been investigated. These results were compared with those obtained for the same conditions of pressure and composition on the ground at 1 g. In this way it was shown how gravity does influence the spreading process and how this influence was affected by pressure and mixture composition

David Jochinke: Productor y Agrónomo australiano

David Jochinke es un joven agricultor y agrónomo por la Universidad de Melbourne y pertenece a una tercera generación de productores de la región de Wimmera en Australia. La revista Agricultura ha tenido la oportunidad de entrevistarle y acompañarle durante su reciente visita a España, como parte del trabajo de investigación que realiza para la prestigiosa asociación The Australian Nuffield Farming Association. El trabajo que ha planteado, y por el que ha sido premiado, estudia cómo los agricultores, por todo el mundo, influyen en las políticas que afectan a la agricultura, tanto a nivel local como a nivel internacional

Indicators of sustainability of agriculture and livestock in Spain - Indicadores de sostenibilidad de la agricultura y ganadería española

Sustainability is an adjective used to characterize agriculture according to the degree of fulfillment of goals. Those goals are related to agro-ecological, environmental and socio-economic dimensions. Sustainability is a dynamic and temporal character. In absolute terms there is not an ending value because it changes as its dimensions make it. Spain is one of the main agricultural countries of the European Union both in terms of crop land and value of productions. The object of this study is to present a methodology of sustainability account to be incorporated into national statistical and to assess their performance in the course of the years. For that reason the data sources used have been the statistics of the Department of Agriculture and from others database. We presented a set of indicators of sustainability and its evaluation in a time series of at least 30 years. The trend analysis offers the evolution of the numerical values of the indicators in terms of efficiency, physical units used for a unit of product or its value in euros. The analyzed crops have been: wheat, barley, maize, sunflower, sugar beet, wine grape, olive oil, citrus, melon and tomato. Physical indicators were: land, water, energy, erosion, soil organic matter, and carbon balance; socio-economic indicators were: agricultural final production, prices, income, employment and use of fertilizers. In general, all crops increased their productive efficiency, higher in irrigated than on dry land. Spanish agricultural carbon sequestration capacity has multiplied by five in the last seventy years, as a result of the increase in the productivity of crops, in terms of total biomass and the modification of the soil management techniques. Livestock sector presents data of pork, broilers and laying hen. Those showed an improvement in efficiency and economic indicators. Overall we can say that Spanish agriculture and livestock subsector have a tendency towards sustainability, being its main threats extreme meteorological factors and the instability of todays markets

Definición y alcance de la reproducción de plantas cultivadas

El objetivo del estudio es establecer, desde una perspectiva científica y técnica, la definición y alcance de los siguientes conceptos “producción”, “reproducción”, “multiplicación” y “propagación” de plantas y material vegetal. Coincidencia y/o diferencias de estos conceptos entre sí, y definición y proceso del injerto en plantas

Entrevista con César González de Miguel :Responsable de proyectos de AgroUniversoAgro : Universo, investigación y tecnología para la empresa

Hace ya muchos años que ingresar en una Escuela de Agricultura no es obtener una plaza de funcionario. Hoy las Universidades españolas desarrollan programas para favorecer al emprendedor y el autoempleo entre sus egresados. Al mismo tiempo que invitan a sus investigadores y técnicos a explotar sus resultados de investigación mediante la constitución de empresas de base tecnológica. AGRICULTURA recoge una de esas experiencias exitosas. AgroUniverso® es una empresa de base tecnológica creada en el entorno de la E.T.S. de Ingenieros Agrónomos de Madrid gracias al emprendimiento llevado a cabo por antiguos alumnos

Agrónomos por el mundo: un futuro sin hambre

Recoge primera graduación de los estudiantes de ingeniería agronómica por la Université du Lac Albert de Mahagi UNILAC (República Democrática del Congo)en 2017. Apadrinar esta primera promoción ha sido un motivo de gran satisfacción, pues es un primer paso para lograr un futuro sin hambre. El hambre cero es el segundo Objetivo de Desarrollo Sostenible (ODS), dentro de los 17 objetivos que promueve la organización de las Naciones Unidas. Como los otros 16, este objetivo deberá estar cumplido antes del año 2030