Hurst Coefficient in long time series of population size: Model for two plant populations with different reproductive strategies

Can the fractal dimension of fluctuations in population size be used to estimate extinction risk? The problem with estimating this fractal dimension is that the lengths of the time series are usually too short for conclusive results. This study answered this question with long time series data obtained from an iterative competition model. This model produces competitive extinction at different perturbation intensities for two different germination strategies: germination of all seeds vs. dormancy in half the seeds. This provided long time series of 900 years and different extinction risks. The results support the hypothesis for the effectiveness of the Hurst coefficient for estimating extinction risk

Variaciones estacionales de las precipitaciones en la vertiente norte de la Península Ibérica

[ES]Se estudia la distribución estacional de la precipitación en la vertiente norte de la Península Ibérica, utilizando datos de 104 observatorios.[EN]The seasonal distribution of the precipitation on the northern slopes of the Iberian Peninsula have been studied using data from 104 Meteorological stations

Claudio Franco Chicco Ressia

Dr. Claudio Chicco was born in Carmagnola (Turin), Italy, on October 24, 1933, becoming a Venezuelan citizen in 1957.El doctor Claudio Chicco nació en Carmagnola (Turín), Italia, el 24 de octubre de 1933, nacionalizándose como venezolano en 1957Dr. Claudio Chicco nasceu em Carmagnola (Turim), Itália, em 24 de outubro de 1933, tornando-se cidadão venezuelano em 1957

Microhardness and friction coefficient of multi-walled carbon nanotube-yttria-stabilized ZrO2 composites prepared by spark plasma sintering

Multi-walled carbon nanotubes (eight walls) are mixed with an yttria-stabilized ZrO2 powder. The specimens are densified by spark plasma sintering. Compared to ZrO2, there is a 3.8-fold decrease of the friction coefficient against alumina upon the increase in carbon content. Examinations of the friction tracks show that wear is very low when the carbon content is sufficient. Exfoliation of the nanotubes due to shearing stresses and incorporation of the debris into a lubricating film over the contact area is probable

Relaciones cuantitativas entre los contaminantes índice y las variables meteorológicas en Salamanca

[ES]En este trabajo hemos cuantificado la relación existente entre las concentraciones diarias de inmisión de dióxido de azufre y materia en suspensión (caracterizada como humos negros) y 8 variables meteorológicas en Salamanca.[EN]In this paper we have obtained the quantitative relationships between the daily sulphur dioxide and suspended particulate matter (characterized as black smoke) concen trations and 8 meteorological parameters in Salamanca

A study of the influence of the wind over the index pollutants in Salamanca

[ES]Hemos estudiado la influencia conjunta del módulo y la dirección del viento sobre las concentraciones de SO2 y la materia en suspensión (caracterizada como humos negros).[EN]The influence that the magnitude and direction of the wind produce together on the SO2 concentration and suspended matter (known as black smoke) have been studied

Turing instabilities in a mathematical model for signaling networks

GTPase molecules are important regulators in cells that continuously run through an activation/deactivation and membrane-attachment/membrane-detachment cycle. Activated GTPase is able to localize in parts of the membranes and to induce cell polarity. As feedback loops contribute to the GTPase cycle and as the coupling between membrane-bound and cytoplasmic processes introduces different diffusion coefficients a Turing mechanism is a natural candidate for this symmetry breaking. We formulate a mathematical model that couples a reaction-diffusion system in the inner volume to a reaction-diffusion system on the membrane via a flux condition and an attachment/detachment law at the membrane. We present a reduction to a simpler non-local reaction-diffusion model and perform a stability analysis and numerical simulations for this reduction. Our model in principle does support Turing instabilities but only if the lateral diffusion of inactivated GTPase is much faster than the diffusion of activated GTPase.Comment: 23 pages, 5 figures; The final publication is available at http://www.springerlink.com http://dx.doi.org/10.1007/s00285-011-0495-

Agronomic treatments to avoid seed presence in `Nadorcott¿ mandarin I. Effect on in vivo pollen tube growth

[EN] Fresh market demands high quality fruit and, therefore, citrus growers and researchers are constantly looking for solutions to avoid seed presence. Current horticultural techniques have low effectiveness or high cost. The objective of this study is to evaluate the inhibition effect of seven products on the in vivo pollen tube growth in Nadorcott mandarin, which is a high-value seedy variety. To achieve this main objective, three inorganic fer­ tilizers (ammonium nitrate, potassium nitrate, sulfur), and four saccharides (saccharose, methyl cellulose, cal­ lose, chitosan) were applied to Nadorcott stigmas 24 h before and after hand pollination. Pollen tubes were counted 1, 3, and 5 days after treatment in longitudinal blue violet autofluorescence-stained sections. Of the seven evaluated products, only sulfur had a strong inhibitory effect. Elemental sulfur (S 8 ) inhibited pollen tube growth by 94-100%. This strong effect was observed regardless of sulfur being applied 24 h before or after pollination, and on fixed flowers 1, 3 or 5 days after applications. Saccharose treatment seemed to have the opposite effect: stimulated pollen tube growth, but the difference with the positive control was small and non- significant. The sulfur effect could be useful for designing agronomic applications capable of preventing seed presence in Nadorcott mandarin.This research was supported by the Asociación Club de Variedades Vegetales Protegidas as part of a project undertaken with the Universitat Politècnica de València (Spain, UPV 20170087), of which H. Merle was the principal researcher. There was no additional external funding received for this study.Garmendia, A.; García-Breijo, F.; Reig, J.; Raigón Jiménez, MD.; Beltrán, R.; Zornoza, C.; Cebrián, N.... (2022). Agronomic treatments to avoid seed presence in `Nadorcott¿ mandarin I. Effect on in vivo pollen tube growth. Scientia Horticulturae. 294:1-10. https://doi.org/10.1016/j.scienta.2021.11076011029