Solving the brachistochrone and other variational problems with soap films

We show a method to solve the problem of the brachistochrone as well as other variational problems with the help of the soap films that are formed between two suitable surfaces. We also show the interesting connection between some variational problems of dynamics, statics, optics, and elasticity.Comment: 16 pages, 11 figures. This article, except for a small correction, has been submitted to the American Journal of Physic

Antiprogestagen RU486 prevents the LH-dependent decrease in the serum concentrations of inhibin in the rat

1. In the rat, the LH-dependent ovarian progesterone rise mediates several actions of the primary surge of LH on the ovary. This experiment was aimed at elucidating the effects of the antiprogestagen RU486 on the LH- dependent decrease in both the serum concentrations and the ovarian content of inhibin. 2. All rats in this experiment were treated with an antagonist of LHRH (1 mg/200 μl saline at 0800 b in proestrus) to supress the endogenous release of LH. One group of rats received 32 μg LH/250 μl saline at 1200h in proestrus. Other group was given 4 mg RU486/200 μl oil at 0800 h in proestrus. The third group was injected with both RU486 and LH. Rats from the control group were injected with 250 μl saline and 200 μl oil. Animals were decapitated at 1700 h in proestrus and trunk blood and ovaries collected to determine the serum concentrations of LH, FSH, progesterone, 17β-estradiol and inhibin as well as the ovarian content of inhibin. 3. The ovulatory dose of LH in LHRHα-treated rats decreased both the serum concentrations and the ovarian content of inhibin and increased the serum concentrations of FSH. The administration of RU486 blocked the effect of LH on the serum concentrations of inhibin but not that on the ovarian content of inhibin. 4. Since the antiprogestagen RU486 blocked the effect of LH on the serum concentrations of inhibin, we conclude that ovarian progesterone, besides mediating the effects of the primary LH surge on the ovulatory process and luteinization, participates in the LH-dependent drop in the serum concentrations of inhibin in proestrous afternoon

A method to construct refracting profiles

We propose an original method for determining suitable refracting profiles between two media to solve two related problems: to produce a given wave front from a single point source after refraction at the refracting profile, and to focus a given wave front in a fixed point. These profiles are obtained as envelopes of specific families of Cartesian ovals. We study the singularities of these profiles and give a method to construct them from the data of the associated caustic.Comment: 12 pages, 5 figure

The District Energy-Efficient Retrofitting of Torrelago (Laguna de Duero – Spain)

The urban growth is estimated to reach up the 66 % by 2050 and consequently the need of resources within the cities will increase significantly. This, combined with the 40 % of energy consumption and 36 % of CO2 emissions of the building sector, makes necessary to accelerate the transition towards more sustainable cities. The CITyFiED project contributes to this transition, aiming to develop an innovative and holistic methodological approach for energy-efficient district renovation and deliver three large scale demonstration cases in the cities of Lund (Sweden), Laguna de Duero (Spain) and Soma (Turkey). CITyFiED methodology consists of several phases that ease the decision-making tasks towards the district renovation, considering the energy efficiency as the main pillar and local authorities as clients. For the case of Torrelago district (Spain) the intervention consists of a set of energy conservative measures including the facąde retrofitting of 143.025 m2 of living space in 31 twelve-storey buildings; the renovation of the district heating network with a new biomass thermal plant; the integration of renewable energy sources, including a micro-cogeneration system, and the installation of individual smart meters. After the renovation action, one-year monitoring campaign is ongoing. The CITyFiED monitoring platform will collect information from the energy systems and deliver environmental, technical, economic and social key performance indicators by March 2019. At the end of the project the achievement of the predefined goals will be verified: Up to 36 % of energy saving and 3,429 tons-CO2/yr emissions saving covering the 59,4 % of the energy consumption with renewable sources.The research and results presented in this paper evolve from activities related to the CITyFiED project, which has received funding from the European Commission under the Grant Agreement no. 609129. This article is the result of cooperative research work of many experts from various countries and we would like to gratefully acknowledge the rest of the CITyFiED partners

Efecto de la profundidad de entierro sobre la viabilidad y peso seco de rizomas de sorgo de alepo (Sorghum halepense L. Pers)

El sorgo de Alepo es considerado una de las malezas más perjudiciales a nivel mundial por su carácter de planta invasora, y ha generado innumerables esfuerzos para conseguir cada día un mejor y mayor control. El objetivo del presente trabajo fue analizar los efectos de la distribución vertical en el suelo y el tiempo de exposición sobre el peso seco, viabilidad y brotación de los rizomas. El ensayo se condujo en la Facultad de Agronomía de la Universidad Nacional de La Pampa, durante los meses de mayo a octubre de 1993. La extracción de muestras se realizó cada 15 días, para determinar la dinámica de las tres variables antes mencionadas. Los resultados obtenidos demostraron que el efecto profundidad afectó las variables en estudio en mayor medida que el tiempo de exposición. Los rizomas ubicados en superficie en el transcurso de los primeros 60 días del ensayo perdieron un 45% del peso seco para luego mantenerse constante, y demostraron una nula viabilidad y brotación. No obstante ello, y en base a un pequeño ensayo dentro del presente trabajo, se pudo apreciar el efecto atenuante de las condiciones ambientales sobre los rizomas del estrato superior al hallarse los mismos cubiertos por una delgada capa de suelo (5 - 10 cm aproximadamente).Director: Ing. Agr. A. D. Golberg, Cátedra de Fisiología Vegetal

GPS, LiDAR and VNIR data to monitor the spatial behavior of grazing sheep

Traditional knowledge about the behavior of grazing livestock is about to disappear. Shepherds well know that sheep behavior follows non-random patterns. As a novel alternative to seeking behavioral patterns, this study quantified the grazing activities of two sheep flocks of Churra breed (both in the same area but separated by 10 years) based on Global Position System (GPS) monitoring and remote monitoring sensing techniques. In the first monitoring period (2009-10), geolocations were recorded every 5 min (4, 240 records), while in the second one (2018-20), records were taken every 30 min (7, 636 records). The data were clustered based on the day/night and the activity (resting, moving, or grazing). An airborne LiDAR dataset was used to study the slope, aspect, and vegetation height. Four visible-infrared orthophotographs were mosaicked and classified to obtain the land use/land cover (LU/LC) map. Then, GPS locations were overlain on the terrain features, and a Chi-square test evaluated the relationships between locations and terrain features. Three spatial statistics (directional distribution, Kernel density, and Hot Spot analysis) were also calculated. Results in both monitoring periods suggested that the spatial distribution of free-grazing ewes was non-random. The flocks showed strong preferences for grazing areas with gentle north-facing slopes, where the herbaceous layer formed by pasture predominates. The geostatistical analyses of the sheep locations corroborated those preferences. Geotechnologies have emerged as a potent tool to demonstrate the influence of environmental and terrain attributes on the non-random spatial behavior of grazing sheep. © 2022 Malque Publishing. All rights reserved