Germination responses to light of four Neotropical forest tree species along an elevational gradient in the southern Central Andes

Seed germination is a key part of plants' life cycle and is mostly affected by the genetic background, the environmental conditions experienced by the mother plant and the seedbed conditions. The germination response to light is essential to optimize germination and seedling establishment in space and time. In addition, the germination response to light is a trait often related to the response of the seeds to their position in the soil (uncovered/buried). Here, we studied the germination response to light of four key tree species of the Yungas forest (Anadenanthera colubrina, Enterolobium contortisiliquum, Jacaranda mimosifolia and Handroanthus impetiginosus) sampled along an elevational and environmental gradient with contrasting vegetation cover and disturbance. Relative light germination (RLG) and mean germination time (MGT) were determined. Final germination was tested under cycles of light (8 h) and darkness (16 h) versus complete darkness (24 h) and elevation, and MGT was tested as a function of elevation of the provenance. The RLG increased from smaller to larger-seeded species. The MGT of three of the studied species was affected by the elevation of the provenance. Complete darkness negatively affected final germination, while two species exhibited a significant interaction between the provenance and light. The variable germination responses to light along the elevational gradient highlights the influence of the environment on germination as a key factor that should be considered for forest management, conservation and restoration projects

Orographic and convective gravity waves above the Alps and Andes mountains during GPS radio occultation events – a case study

The significant distortions introduced in the measured atmospheric gravity wavelengths by soundings other than in vertical and horizontal directions, are discussed as a function of elevation angle of the sounding path and the gravity waves aspect ratio. Under- or overestimation of real vertical wavelengths during the measurement process depends basically on the value of these two parameters. The consequences of these distortions on the calculation of the energy and vertical flux of horizontal momentum are analyzed and discussed in the context of two experimental limb satellite setups: GPS-LEO radio occultations and TIMED/SABER measurements. Possible discrepancies previously found between the momentum flux calculated from satellite temperature profiles, on site and from model simulations, may, to a certain degree, be attributed to these distortions. A recalculation of previous momentum flux climatologies based on these considerations seems to be a difficult goal.Fil: Hierro, Rodrigo Federico. Universidad Austral. Facultad de Ingeniería. Departamento de Ciencias Básicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Steiner, Andrea K.. Universidad de Graz; AustriaFil: de la Torre, Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Austral. Facultad de Ingeniería. Departamento de Ciencias Básicas; ArgentinaFil: Alexander, Pedro Manfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Llamedo Soria, Pablo Martin. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Austral. Facultad de Ingeniería. Departamento de Ciencias Básicas; ArgentinaFil: Cremades, Pablo Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales; Argentin

Dynamic parameter estimation problem for ethanol production from seaweed

Ethanol has been studied extensively as one of the current and probably future energy vectors. Fermentation of hydrolysed oligosaccharides from macroalgae biomass to ethanol has been certified, and several processing options have been proposed. In the present work, we model the production of ethanol based on Laminaria, a seaweed genus that belongs to the so-called "brown algae" group, as the carbon source. In brown algae, the most relevant sugars that can be used as substrate for fermentation are mannitol -the alcohol form of the sugar mannose- and laminaran, a linear polysaccharide of(1,3)-β-Dglucopyranose. We consider the yeast Pichia angophorae as the fermenting microorganism. The model includes dynamic mass balances for biomass, ethanol, mannitol and laminaran. Growth is controlled via limiting functions that modify the biomass equation for temperature and oxygen transfer rate (OTR). It is also modified by including a term that considers inhibition by ethanol. Based on the proposed model, a dynamic parameter estimation problem is formulated, the objective function being weighted least-squares fit to data, subject to the mass balance equations. The data set for parameter estimation was obtained in batch liquid cultures, with experiments performed over 40 hours. Numerical results provide useful insights on ethanol production using macroalgae biomass as carbon sourceFil: Delpino, Claudio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: de Genaro, Pablo Adrian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Di Maggio, Jimena Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Estrada, Vanina Gisela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Díaz, María Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentin

Reactivity of Fluorinated-Chalcone Phosphines, RPEWO-F4, Induced by C–F Activation upon Coordination to PdCl2

Producción CientíficaThe E phosphine ligands (R = Ph, o-Tol, Cy), abbreviated as RPEWO-F4, are stable in solution, but they develop a rich reactivity on coordination to PdCl2. The chelate P-olefin coordination to PdCl2 leads eventually to a Z conformation of the fluorinated-chalcone group o-C6F4CH═CHC(O)Ph. From there, a cyclization reaction occurs involving the C═O group and activation of a F atom, yielding a strongly chelated PdCl2(P-carbene) complex. The carbene carbon atom in the complex displays some electrophilicity, which is expressed in hydrolysis, ammonolysis, and oxidation (with peroxide) reactions, affording PdCl2 complexes with new P,C,O-pincer, P,C,N-pincer, or P,O-chelate fluorinated ligands. The C–F activation reactions are slow in comparison to the catalysis rates when the [PdCl2(RPEWO-F4)] complexes have been used in Negishi catalyses. Consequently, the reactivity discussed here is not expected to interfere with the interpretation of the data obtained in Pd-catalytic studies or processes, at least for fast transmetalating nucleophiles.Ministerio de Economía, Industria y Competitividad (projects CTQ2017-89217-P and CTQ2016-80913-P)Junta de Castilla y León (projects VA051P17 and VA062G18

Unraveling beam self-healing

We show that, contrary to popular belief, non only diffraction-free beams may reconstruct themselves after hitting an opaque obstacle but also, for example, Gaussian beams. We unravel the mathematics and the physics underlying the self-reconstruction mechanism and we provide for a novel definition for the minimum reconstruction distance beyond geometric optics, which is in principle applicable to any optical beam that admits an angular spectrum representation. Moreover, we propose to quantify the self-reconstruction ability of a beam via a newly established degree of self-healing. This is defined via a comparison between the amplitudes, as opposite to intensities, of the original beam and the obstructed one. Such comparison is experimentally accomplished by tailoring an innovative experimental technique based upon Shack-Hartmann wave front reconstruction. We believe that these results can open new avenues in this field

Run-and-tumble bacteria slowly approaching the diffusive regime

The run-and-tumble (RT) dynamics followed by bacterial swimmers gives rise first to a ballistic motion due to their persistence, and later, through consecutive tumbles, to a diffusive process. Here we investigate how long it takes for a dilute swimmer suspension to reach the diffusive regime as well as what is the amplitude of the deviations from the diffusive dynamics. A linear time dependence of the mean-squared displacement (MSD) is insufficient to characterize diffusion and thus we also focus on the excess kurtosis of the displacement distribution. Four swimming strategies are considered: (i) the conventional RT model with complete reorientation after tumbling, (ii) the case of partial reorientation, characterized by a distribution of tumbling angles, (iii) a run-and-reverse model with rotational diffusion, and (iv) a RT particle where the tumbling rate depends on the stochastic concentration of an internal protein. By analyzing the associated kinetic equations for the probability density function and simulating the models, we find that for models (ii), (iii), and (iv) the relaxation to diffusion can take much longer than the mean time between tumble events, evidencing the existence of large tails in the particle displacements. Moreover, the excess kurtosis can assume large positive values. In model (ii) it is possible for some distributions of tumbling angles that the MSD reaches a linear time dependence but, still, the dynamics remains non-Gaussian for long times. This is also the case in model (iii) for small rotational diffusivity. For all models, the long-time diffusion coefficients are also obtained. The theoretical approach, which relies on eigenvalue and angular Fourier expansions of the van Hove function, is in excellent agreement with the simulations.Comment: 12 pages, 4 captioned figures. Accepted for publication in Physical Review

Exploring alternative practices in urban water management through the lens of circular economy: a case study in the Barcelona metropolitan area

Urban water management has recently been questioned because of the fragmented nature of the urban water system and its linear model. The integration and management of water systems are currently recognized as a socio-technical challenge that must be addressed for a more sustainable urban water management. In the short term, a key factor for its transition will be integration of alternative practices that allow for experimentation, learning, and scaling up. This study aims to identify potential shifts supported by two alternative practices for water reuse: nature-based solutions and water reuse technologies, using circular economy principles as analytical categories. The research uses a case study, the Besòs river of the Barcelona metropolitan area, to show that: i) improving biodiversity and water quality helps to regenerate natural capital; ii) water reuse for streamflow augmentation keeps resources in use and promotes synergies, which benefits social livability; and iii) risk management and a potential fit-to-purpose strategy can marginally help to avoid waste externalities. This research has shown that the CE principles are applicable as a framework for identifying the interconnected shifts promoted by water systems. A reflexive understanding of the alternative practices provides deeper insight into the experiences, barriers, and shifts that allow innovative interactions in specific urban contexts and can deliver additional benefits for society. This knowledge can be useful for integrated urban management; however, further integration of cross-sectoral collaboration and flexibility are required.Peer ReviewedPostprint (published version

Brechas en la movilidad urbana argentina frente a los objetivos de desarrollo sustentable (ODS 11.2.1)

Indicator 11.2.1 of the Sustainable Development Goals (SDGs) refers to urban mobility. The metadata of the 2030 Agenda SDG Argentina specifies its measurement according to the number of households located within 300 meters of public transport, using as source the Nacional Census of Population. Although this metric was collected during the 2001 and 2010 censuses, its results haven't been thoroughly examined. The goal of this article is to establish a baseline of the access of urban public transport using the microdata from the 2010 Census. The methodology employs global metadata and official sources and yields results on indicator 11.2.1 at the census tract level. As a result, information on indicator 11.2.1 is provided at the census tract level for the entire country. The results reveals inequalities by region, province, urban system and within urban areas, which are valuable for the necessary territorialization of the Agenda 2030.El indicador 11.2.1 de los Objetivos de Desarrollo Sustentable refiere a la movilidad en las ciudades. Los metadatos de la Agenda 2030 Argentina establecen su medición conforme a la cantidad de hogares que se encuentran a menos de 300 metros de algún modo de transporte público, y como fuente al Censo de Población, Hogares y Viviendas. Si bien los datos fueron relevados por los Censos 2001 y 2010, sus resultados no han sido analizados en forma desagregada hasta la fecha. El objetivo del artículo es establecer una línea de base acerca del acceso al transporte público en Argentina utilizando los microdatos del Censo 2010. La metodología se ajusta a los metadatos globales y combina fuentes oficiales. Como resultado se obtiene información del indicador 11.2.1 a nivel de radio censal para todo el país. El análisis de resultados muestra desigualdades por región y provincia, a nivel del sistema urbano nacional e intra-urbanas, cuyo diagnóstico aporta a territorializar la Agenda 2030