Riemannian metrics on an infinite dimensional symplectic group

The aim of this paper is the geometric study of the symplectic operators which are a perturbation of the identity by a Hilbert-Schmidt operator. This subgroup of the symplectic group was introduced in Pierre de la Harpe's classical book of Banach-Lie groups. Throughout this paper we will endow the tangent spaces with different Riemannian metrics. We will use the minimal curves of the unitary group and the positive invertible operators to compare the length of the geodesic curves in each case. Moreover we will study the completeness of the symplectic group with the geodesic distance.Comment: 18 pages. The final version of this preprint will appear in Journal of Mathematical Analysis and Application

Effect of ultrasonication on microbial quality, colour and ascorbic acid of passion-fruit juice during storage

Passion fruit juice (PFJ) has a delicate flavour very susceptible to thermal degradation. This study pursued to test the effect of sonication as non-thermal preservation method on some quality parameters of PFJ. The effect of ultrasound (20 kHz, 263 W, 89.25 µm) on the indigenous microflora, colour and ascorbic acid content of PFJ was studied. Firstly, the kinetic of microbial inactivation was determined for aerobic mesophilic counts and yeasts counts. Data was fitted to Weibull model, and a treatment time of 8 min was selected for stability studies. To this, untreated and sonicated juice was stored at 4 and 10 ºC up to 10 days and microbial quality, instrumental colour, pH and ascorbic acid content were evaluated. In general, ultrasound kept juice microbiologically stable for up to 10 days at 4 ºC without markedly affecting other parameters evaluated. Ultrasound seems suitable to stabilize microbiologically PFJ.Ciencias de la Alimentació

Respuesta de la producción al riego en almendro: riego deficitario y función de producción

Introduction Almond is becoming a very extended tree crop in Spain, due to good prices in the last years and likewise good market perspectives. A fast intensification process is taking place; new plantations (of which the acreage has doubled from 2014 to 2016) have nothing to do with the traditionally marginal rainfed crop producing around 150 kg/ha. Instead, taking after the Californian scheme, some of them are sited in deep and fertile soils, receive much less pruning and more inputs for nutrition and crop protection, and are usually irrigated. However, water availability is lower here in Spain than in California or Australia, where irrigation allocation for almond is about 12,000 m3·ha-1. On the other hand, rainfall is somewhat higher in Spain. In addition, breeding programs have led to self-fertile and hard-shelled cultivars in Spain whereas self-incompatible and soft-shelled ones, such as Nonpareil, are more common in California. All these differences have generated a need for information about irrigation requirements of intensive almond orchards in our conditions. Research content In the present thesis, first, maximum crop transpiration (T) was measured by both a large weighing lysimeter and calibrated sap-flow probes, concluding that mid-stage transpiration coefficient (KT) of a fully mature almond orchard (covering 85% of soil) should be around 1.04, but could be affected by high fruit loads. Measuring transpiration instead of evapotranspiration (ET) made our findings more easily transferable throughout different conditions, despite different irrigation management alternatives (for instance, one or two drip lines, or microsprinklers; the three of them presenting different soil wetting patterns). Then, we conducted water balance (WB) measurements on both fully and deficit irrigated (DI) almond four-trees-subplots, to get a relation between irrigation (IR) regimes and actual water use (ETa). Evaporation from soil (ES) was modelled and detracted from evapotranspiration to calculate transpiration values. This method was compared to direct transpiration estimates from sap-flow. Conclusions Almonds were found able to consume up to 200 mm from the soil reservoir and to extract water from deeper than 2 meters. Finally, kernel yield and its components (fruit load and kernel unit weight) were related to all three, irrigation, evapotranspiration, and transpiration, thus establishing the water production functions for almond. Irrigation water marginal productivity (IWMP) ranged from 0.33 kg·m-3 in the most severe DI treatment to 0.11 kg·m-3 in the full irrigated treatment.Introducción El almendro se está convirtiendo en un cultivo leñoso muy extendido en España, debido a los buenos precios en los últimos años y a las buenas perspectivas de mercado. Está teniendo lugar un rápido proceso de intensificación: las nuevas plantaciones (cuya superficie se duplicó entre 2014 y 2016) no tienen nada que ver con el cultivo tradicional, marginal, en secano y con rendimientos de unos 150 kg/ha. En cambio, siguiendo el esquema de California, estas nuevas plantaciones intensivas reciben mucha menos poda y más insumos tanto fertilizantes como fitosanitarios, están generalmente en riego y la mayoría se encuentran en suelos profundos y fértiles. Sin embargo, la disponibilidad de agua de riego es más baja aquí en España que en California o Australia, donde la dotación de riego para el almendro es de aproximadamente 12.000 m3·ha-1. Por otro lado, las precipitaciones son más altas en España. Además, los programas de mejora genética han llevado en España a variedades autocompatibles y autofértiles, y de cáscara dura, mientras que en California se han preferido los cultivares auto-incompatibles y de cáscara blanda como Nonpareil. Estas diferencias han generado una necesidad de información sobre las necesidades de riego de las plantaciones intensivas de almendro en nuestras condiciones. Contenido de la investigación En primer lugar, la transpiración máxima del cultivo se midió con un lisímetro de pesada y con sondas de flujo de savia calibradas. Se concluyó que el coeficiente de transpiración máximo de una plantación de almendros en plena producción (con un porcentaje de cobertura de suelo del 85%) debería rondar 1,04, pero podría verse afectado por niveles altos de carga. Medir la transpiración en lugar de la evapotranspiración hace que nuestros hallazgos puedan ser más fácilmente transferibles a diferentes condiciones, a pesar de las diferentes alternativas de manejo del riego (por ejemplo, una o dos líneas de goteo o microaspersores, cada uno con un distinto patrón de mojado del suelo). Posteriormente, se hicieron medidas de balance de agua en 16 subparcelas de 4 árboles, donde se aplicaron un tratamiento de riego para satisfacer el total de las necesidades hídricas y tres tratamientos de riego deficitario, a fin de establecer una relación entre los regímenes de riego y el uso consuntivo de agua. La evaporación del suelo se modeló y se restó de la evapotranspiración para obtener la transpiración de los árboles. Esta metodología se contrastó con medidas directas de transpiración con sensores de flujo de savia. Conclusiones Se comprobó que los almendros pueden consumir hasta 200 mm del depósito del suelo y extraer agua a más de 2 metros de profundidad. Finalmente, se hallaron relaciones entre el rendimiento y sus componentes (carga de fruta y peso unitario del grano) y riego, evapotranspiración y transpiración, respectivamente, estableciendo así la función de producción de agua del almendro. La productividad marginal del agua de riego fue de 0.33 kg·m-3 en el tratamiento de riego deficitario más estresado a 0.11 kg·m-3 en el tratamiento control

Measuring Social carrying Capacity: An Exploratory Study

The tourist carrying capacity commands a growing interest given that it is closely linked with sustainable tourist development. The justification of the utility of this concept is given by means of a simple and efficient methodological proposal, by analysing the social carrying capacity. To this end, an empirical application is carried out in the Western Andalusia. In some of the cases analysed, the satisfaction of the tourist is found to decline when the levels of the tourist use are higher with respect to those attributes of the tourist destination supply. This mechanism can constitute a useful alarm signal for tourism planners.carrying capacity, tourist satisfaction, sustainable tourism, tourist destination.

The geometric representations in the books of text used in the Autonomous Community of Extremadura

Se recogen los principales resultados de una investigación sobre la visualización de la Geometría en libros de texto actuales de Matemáticas de las editoriales de mayor uso en Extremadura (SM, Anaya y Santillana). El estudio se centra en la variedad de representaciones al introducir las figuras y conceptos geométricos, los elementos de las imágenes que puedan derivar en dificultades en el proceso de enseñanza-aprendizaje de la Geometría, la representación plana de figuras tridimensionales y las imágenes reales que se utilizan para aludir a elementos geométricos abstractos.The main results of a research on the visualization of the Geometry in present-day Mathematics text books of the more used editorials in Extremadura (SM, Anaya and Santillana) are collected. Study focuses on the variety of representations in the introduction of the figures and geometrical concepts, the elements of the images which could lead to difficulties in the Geometry teaching-learning process, the plane representation of tridimensional figures and the real images that are used to refer to abstract geometrical elements.peerReviewe

The influence of social value and selfcongruity on interpersonal connections in virtual social networks by Gen-Y tourists

This research focuses on the relationship of self-congruity and perceived social value with the interpersonal connections established by Generation Y tourists in virtual social networks. A quantitative study was performed using a sample of young travelers from Spain. The methodologies of Confirmatory Factor Analysis (CFA) and Structural Equation Models (SEM) were used to analyze the results. The findings of the research show that self-congruity influences the perceived social value; the perceived social value leads to satisfaction and the creation of interpersonal connections in virtual social networks; and the interpersonal connections in virtual social networks influence the use of these tools by Generation Y travelers