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El objetivo de este estudio fue examinar las propiedades psicométricas (estructura factorial, fiabilidad, validez de constructo) de una versión en español hablado en México de la Escala de Motivación en el Deporte revisada (SMS-II) compuesta por 18 ítems que miden seis factores de regulación conductual planteados por la teoría de la autodeterminación, y probar un modelo que permitiese evaluar la motivación autónoma y la motivación controlada. Participaron 279 deportistas de alto rendimiento con una edad promedio de 23.15 años (DT = 5.58), quienes respondieron a una versión en español hablado en México de la SMS-II. Los resultados apoyaron el modelo de seis factores de primer orden (motivación intrínseca, regulación integrada, regulación identificada, regulación introyectada, regulación externa, y desmotivación) tras la eliminación de un ítem; y los datos de consistencia interna superaron o estuvieron al límite de los criterios de uso en cinco factores. Cuando las regulaciones motivacionales se combinaron para conformar un modelo trifactorial, dos de sus factores de segundo orden (motivación autónoma y motivación controlada) más un factor de primer orden (desmotivación), se soportó dicho modelo, y la consistencia interna de los factores fue adecuada. En conclusión se ofrece validez factorial y de constructo de esta versión en español hablado en México de la Escala de Motivación en el Deporte revisada con la exclusión un ítem, y puede utilizarse para la medición de la motivación controlada y autónoma en el deporte de alto rendimiento, aunque se requiere de mayor estudio para mejorar el instrumento. The aim of this study was to analyze the psychometric properties (factorial structure, reliability, construct validity) of a Mexican Spanish version of the revised Sport Motivation Scale (SMS-II), which is composed of 18 items that measure six factors of behavioral regulation. Such factors were suggested by the Self-determination Theory in order to prove a model that allows the assessment of Autonomous and Controlled Motivation. The study involved 279 high performance athletes with an average age of 23.15 years old (SD = 5.58), who answered the Mexican Spanish Version of the SMS-II. After eliminating one of the items, the results supported the six major factor model (intrinsic motivation, integrated regulation, identified regulation, introjected regulation, external regulation and amotivation); and the internal consistent data exceeded or were under the limit of the usage criteria in five of the factors. After the motivational regulations were combined in order to form a three-factor model, two of the minor factors (autonomous and controlled motivation) plus one major factor (amotivation), such model was supported and the internal consistency of the factors was appropriate. In conclusion, the Mexican Spanish version of the SMS-II offers factorial structure and construct validity, excluding one of the items. Thus, it can be used for assessing autonomous and controlled motivation in elite athletes, even though further res...

The aim of this study is the deduction of an analytic representation of the optimal irrigation flow depending on the border length, hydrodynamic properties, and soil moisture constants, with high values of the coefficient of uniformity. In order not to be limited to the simplified models, the linear relationship of the numerical simulation with the hydrodynamic model, formed by the coupled equations of Barré de Saint-Venant and Richards, was established. Sample records for 10 soil types of contrasting texture were used and were applied to three water depths. On the other hand, the analytical representation of the linear relationship using the Parlange theory of infiltration proposed for integrating the differential equation of one-dimensional vertical infiltration was established. The obtained formula for calculating the optimal unitary discharge is a function of the border strip length, the net depth, the characteristic infiltration parameters (capillary forces, sorptivity, and gravitational forces), the saturated hydraulic conductivity, and a shape parameter of the hydrodynamic characteristics. The good accordance between the numerical and analytical results allows us to recommend the formula for the design of gravity irrigation.

In gravity irrigation, how water is distributed in the soil profile makes it necessary to study and develop methodologies to model the process of water infiltration and redistribution. In this work, a model is shown to simulate the advancing front in border irrigation based on the one dimensional equations of Barré de Saint-Venant for the surface flow and the equation of Green and Ampt for the flow in a porous medium. The solutions were obtained numerically using a finite difference Lagrangian scheme for the surface flow and the Raphson method for the subsurface flow. The model was validated with data obtained from the literature from an irrigation test and its predictive capacity was compared with another model and showed excellent results. The hydrodynamic parameters of the soil, necessary to obtain the optimal irrigation discharge, were obtained through the solution of the inverse problem using the Levenberg–Marquardt optimization algorithm. Finally, the results found here allow us to recommend that this model be used to design and model border irrigation, since the infiltration equation uses characteristic parameters of the physical soil.

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Los efectos económicos y sociales que la pandemia del COVID-19 y las medidas asociadas para hacerle frente están teniendo en América Latina pueden derivar en serias consecuencias de largo plazo que repercutirían en el logro de los Objetivos de Desarrollo Sostenible (ODS). En este artículo, resultado de la colaboración de economistas ambientales de ocho países de la región, discutimos los posibles efectos de la pandemia en la contaminación del aire, la deforestación y otros aspectos ambientales relevantes relacionados con los ODS. Además de presentar un recuento de algunos de los efectos iniciales de la crisis sanitaria en el medio ambiente, discutimos efectos potenciales en términos de regulaciones ambientales e intervenciones de política pública. Por último, presentamos una agenda sobre nuevos temas de investigación que surgen a raíz de la pandemia o que han cobrado mayor importancia como consecuencia de esta, incluyendo los impactos sobre el logro de los ODS.

Soil water movement is important in fields such as soil mechanics, irrigation, drainage, hydrology, and agriculture. The Richards equation describes the flow of water in an unsaturated porous medium, and analytical solutions exist only for simplified cases. However, numerous practical situations require a numerical solution (1D, 2D, or 3D) depending on the complexity of the studied problem. In this paper, numerical solution of the equation describing water infiltration into soil using the finite difference method is studied. The finite difference solution is made via iterative schemes of local balance, including explicit, implicit, and intermediate methods; as a special case, the Laasonen method is shown. The found solution is applied to water transfer problems during and after gravity irrigation to observe phenomena of infiltration, evaporation, transpiration, and percolation.

In Mexico, agriculture has an allowance of 76% of the available water (surface and underground), although the average application efficiencies are below 50%. Despite the fact that in recent years modern pressurized irrigation systems have been the best option to increase the water-use efficiency (WUE), the gravity irrigation system continues to be the most used method to provide water to crops. This work was carried out during the 2014–2019 period in three crops, namely, barley, corn, and sorghum, in an irrigation district, showing the results of a methodology applied to gravity irrigation systems to increase the WUE. The results show that, with an efficient design, by means of irrigation tests, characterization of the plot, and the calculation of the optimal flow through an analytical formula, it was possible to reduce the irrigation times per hectare and the irrigation depth applied. Application efficiencies increased from 43% to 95%, while the WUE increased by 27, 38, and 47% for sorghum, barley, and corn, respectively. With this methodology, farmers are more attentive in irrigation because the optimal flow in each furrow or border is, in general, higher than that applied in the traditional way and they take less time to irrigate their plots. For farmers to adopt this methodology, the following actions are required: (a) be aware that the water that comes from dams is as valuable as the water from wells; (b) increase the irrigation quota; (c) seek government support to increase the WUE; and (d) show them that with less water they can have better yields.