L’impact de la désertification et des systèmes agro-industriels sur les déplacements humains

ANR DEMOENV La démocratie face aux enjeux environnementau

Acidophilic phytoplankton in Argentina: the case study of Lake Caviahue (Patagonia)

This article presents a review of the studies carried out over a 10-year period in Lake Caviahue, a natural acidic lake located in Patagonia. The main patterns of the phytoplankton populations are described. Five extremophiles phytoplanktonic species were studied in relation to the zooplankton and nutrients bioavailability under the environmental conditions registered in Lake Caviahue: very low pH (~3), high concentrations of iron (18.4 mg L-1) and sulphur (130 mg L-1). During the 10-years studies, the biomass (0.2 and 1.4 mg fw L-1) and the biodiversity were very low being Keratococcus rhaphidioides the dominant species (60 to 100% of the total biomass). Philodina sp. (Bdelloidea) was the only zooplankter responsible of the zooplankton biomass. From the lack of relationship between phytozooplankton biomass, as well as from the results obtained in the feeding experiments, we conclude that no control of algal abundance by the zooplankton occurs. The microalgae were nitrogen limited in the lake and according to the results from experiments with nutrient addition, the phytoplankton showed nitrogen limitation on growth rate and yield. The species have also the capacity to use mixotrophically alternative sources of organic and inorganic carbon and organic nitrogen. The importance of the uptake and the expression of CO2 concentrating mechanisms (CCMs) were demonstrated in Euglena and in the ellipsoidal form of Watanabea but not in the spherical form of Watanabea and in Palmellopsis. The two forms of Watanabea differed in their possession of a CCM.Fil: Diaz, Monica Mabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación en Biodiversidad y Medioambiente; ArgentinaFil: Beamud, Sara Guadalupe. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación en Biodiversidad y Medioambiente; Argentin

Phase Composition and Transport Properties of oxide ion conductors based on Sr1-xKxGeO3-x/2

Oxide ion conductors have been increasingly studied because of their potential applications in different electrochemical devices, such as, oxygen sensors, membranes for oxygen separation and components of fuel cells. Solid Oxide Fuel Cells (SOFCs) are electrochemical devices that operate at high temperatures, 600-1000 ºC, with higher efficiency for electrical generation than conventional systems based on fuel combustion. The high operating temperatures of the SOFC is mainly due to the limited ionic conductivity of the electrolyte. Zr0.84Y0.16O1.92 (YSZ) is the electrolyte most widely used in commercial systems due to its high stability and oxide ion conductivity at elevated temperatures (900-1000 ºC). However, there is a great interest in the development of devices with lower operation temperatures (600-800 ºC) to overcome collateral problems like difficulties in cell sealing or shorter lifetime of the components caused by the high operation temperature of YSZ. The high oxide ion conductivities recently reported in Na- and K-doped strontium silicates and germanates, make them potentially suitable for SOFC electrolytes. In this work, the structure, microstructure and electrical properties of Sr1-xKxGeO3-x/2 (x = 0.0, 0.1, 0.15 and 0.2) compounds have been re-investigated. The materials have been prepared by conventional ceramic and freeze-drying precursor methods. Different phases are stabilized depending on the synthetic method and the sintering temperature. Samples prepared by freeze-drying at 700 ºC exhibit a triclinic structure, which transforms to a mixture of monoclinic and trigonal related phases on heating at 1000 ºC. The presence of some broad diffractions peaks, which are not fitted in the Rietveld analysis, indicates the existence of an amorphous or low-crystalline phase (ACn) that have been quantified by an external standard procedure (G-factor approach). The homogeneity and chemical composition of the samples were checked by scanning electron microscopy combined with energy dispersive spectroscopy (EDX). The total conductivity of these materials was studied by impedance spectroscopy.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Reconstruction of aridity for the Sierra de la Laguna, Baja California Sur, Mexico

A well-documented history of past climatic conditions is needed to understand and resolve some ecological problems, but the existing climatological records are too short to detect long-term climatic variability and changes. Some trees, such as pines, produce annual tree rings with different widths depending on prevailing environmental conditions, such as climate. Tree-ring analysis of long-lived trees can be used to estimate past variations in climate. The principal aim of this study is to reconstruct aridity for the southern portion of the Baja California Peninsula, by means of dendroclimatologic techniques

Screening for extracts with insect antifeedant properties in native plants from central Argentina

Se evaluaron los extractos etanólicos obtenidos de las partes aéreas de 64 plantas de la región Central de Argentina, como antialimentarios de insectos mediante ensayos de elección, contra Epilachna paenulata (Coleoptera: Coccinellidae). Los extractos derivados de Achyrocline satureioides (Asteraceae), Baccharis coridifolia (Asteraceae), Baccharis flabellata (Asteraceae), Ruprechtia apetala (Polygonaceae) y Vernonanthura nudiflora (Asteraceae) mostraron mas de 97% de inhibición de la alimentación de E. paenulata a 100 μg/cm2. Estos extractos fueron posteriormente evaluados en su efectividad contra Spodoptera frugiperda (Lepidoptera: Noctuidae). Todos ellos, con excepción del extracto de A. satureioides, afectaron negativamente el comportamiento alimentario de S. frugiperda a 100 μg/cm2.Ethanol extracts obtained from aerial parts of 64 native plants from Central Argentina were tested for their insect antifeedant activity against Epilachna paenulata (Coleoptera: Coccinellidae) by choice test. Extracts derived from Achyrocline satureioides (Asteraceae), Baccharis coridifolia (Asteraceae), Baccharis flabellata (Asteraceae), Ruprechtia apetala (Polygonaceae) and Vernonanthura nudiflora (Asteraceae), showed more than 97% inhibition of the feeding of E. paenulata at 100 μg/cm2 . These active extracts were further evaluated for their effectiveness against Spodoptera frugiperda (Lepidoptera: Noctuidae). All these extracts except for that derived from A. satureioides, negatively influenced the feeding behavior of S. frugiperda at 100 μg/cm2 .Fil: del Corral, Soledad. Universidad Catolica de Córdoba. Facultad de Ciencias Químicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Diaz Napal, Georgina Natalia. Universidad Catolica de Córdoba. Facultad de Ciencias Químicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Zaragoza, Mariano. Universidad Catolica de Córdoba. Facultad de Ciencias Químicas; ArgentinaFil: Carpinella, Maria Cecilia. Universidad Catolica de Córdoba. Facultad de Ciencias Químicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ruiz, Gustavo Miguel. Universidad Católica de Córdoba. Facultad de Ciencias Agropecuarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Palacios, Sara Maria. Universidad Catolica de Córdoba. Facultad de Ciencias Químicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

The dual nature of mismatch repair as antimutator and mutator:for better or for worse

DNA is constantly under attack by a number of both exogenous and endogenous agents that challenge its integrity. Among the mechanisms that have evolved to counteract this deleterious action, mismatch repair (MMR) has specialized in removing DNA biosynthetic errors that occur when replicating the genome. Malfunction or inactivation of this system results in an increase in spontaneous mutability and a strong predisposition to tumor development. Besides this key corrective role, MMR proteins are involved in other pathways of DNA metabolism such as mitotic and meiotic recombination and processing of oxidative damage. Surprisingly, MMR is also required for certain mutagenic processes. The mutagenic MMR has beneficial consequences contributing to the generation of a vast repertoire of antibodies through class switch recombination and somatic hypermutation processes. However, this non-canonical mutagenic MMR also has detrimental effects; it promotes repeat expansions associated with neuromuscular and neurodegenerative diseases and may contribute to cancer/disease-related aberrant mutations and translocations. The reaction responsible for replication error correction has been the most thoroughly studied and it is the subject to numerous reviews. This review describes briefly the biochemistry of MMR and focuses primarily on the non-canonical MMR activities described in mammals as well as emerging research implicating interplay of MMR and chromatin

Summer phytoplankton composition and nitrogen limitation of the deep, naturally-acidic (pH∼2.2) Lake Caviahue, Patagonia, Argentina

AbstractDuring the warm seasons of 1998–2004, the naturally-acidic (pH∼2.2) Lake Caviahue was sampled for conductivity, temperature, oxygen, light, nutrients, and phytoplankton (density, biomass and chlorophyll a) with a view to studying the summer phytoplankton population changes with relation to environmental factors, as well as the significance of nitrogen limitation on the phytoplankton yield. Lake Caviahue is characterized by its low transparency, CO2, and N concentration; significant P values; a distinctive vertical distribution of phytoplankton biomass with high values along the water column; and sometimes maximum meta-hypolimnion values. Biodiversity is very low as a result of extreme environmental conditions, Chlorophyceae being the prevailing algae group. Two types of bioassays were carried out to assess nitrogen limitation. For the first bioassay, a solution of ammonium–nitrogen chloride and/or wastewater (rich in ammonium and phosphorus) was used, while one of the lake's sediments was the source of nutrients for the second bioassay. Contrary to the case of acidic mining lakes, N-ammonium proved to be a significant supportive capacity limiting factor as to phytoplankton yield. The present paper provides for the first time information on phytoplankton nitrogen limitation in a naturally-acidic lake

Activity Based Costing System (ABC) : implementation in a supermarket

Treball Final de Grau en Finances i Comptabilitat. Codi: FC1049. Curs: 2014/2015The current high level of competence requires any organization to dispose of an optimum cost control. The Activity-Based Costing (ABC) System enables creating a strategic planning in the firm and in the cost management and it also offers adjusted cost computing. In this project we present an ABC cost model for a supermarket, adapting such model to the characteristics of the sector and the firm by analyzing its cost structure and specifying the daily activity in the store. This is made with a view to create a cost management system adapted to the needs of the firm that will allow it to optimize costs and make strategic decisions