ANÁLISIS DEL IMPACTO DEL USO DE AGROQUÍMICOS EN SISTEMAS AGRÍCOLAS CONVENCIONALES SOBRE SISTEMAS DE BASE AGROECOLÓGICA CERCANOS. SUS CONSECUENCIAS PARA UNA AGRICULTURA

La actividad agroproductiva en Latinoamérica se ha expandido acompañada del paquete tecnológico basado en organismos genéticamente modificados, siembra directa y el uso de plaguicidas, alcanzando en Argentina, 317 millones de L-Kg aplicados en el año 2012. Como alternativa de producción sustentable han surgido emprendimientos agroecológicos que no utilizan estos compuestos, y se desarrollan en zonas rodeadas por prácticas agronómicas que sí los utilizan. Sin embargo, la dinámica y estabilidad ambiental de los plaguicidas y su liberación continua favorecen a que los sistemas agroecológicos se vean afectados por las prácticas de los vecinos. En este contexto, el objetivo general de la tesis es estudiar potenciales impactos adversos del uso de plaguicidas en agroecosistemas convencionales sobre sistemas agroecológicos cercanos y sus consecuencias para una agricultura sustentable. Se estudiarán dos sistemas reales de producción agroecológica en la Provincia de Buenos Aires: uno extensivo agrícola ganadero (“La Aurora”, en Benito Juárez) y otro intensivo hortícola (“La Nueva Era”, Cinturón Hortícola Platense, Lisandro Olmos). Se seleccionarán puntos de muestreo según la extensión espacial y las características de contorno con productores vecinos (barrera forestal, alambrado) a distintas distancias desde los límites vecinos, de forma estacional según aplicaciones usuales de los cultivos de la región. Se colectarán muestras de suelo, aire (material particulado sedimentable y fase gaseosa), material biológico (lombrices) y agua (lluvia, de riego o superficial según el uso y las características de cada establecimiento). Sobre las mismas se analizarán residuos de herbicidas, insecticidas y fungicidas orgánicos, mediante técnicas estandarizadas de extracción y análisis cromatográfico. Con los plaguicidas más detectados en suelos, se realizará bioensayos estandarizados con lombrices (Eisenia Foetida) criadas en laboratorio, para evaluar efectos biológicos como indicador del impacto sobre la agrodiversidad. Por último, en base a estrategias existentes y datos bibliográficos, se analizará comparativamente los resultados obtenidos en el presente estudio en relación con la presencia/ ausencia de barreras y sus características (ancho, pendiente, cobertura vegetal, tipo de vegetación) en zonas limítrofes entre los sistemas productivos agroecológicos y convencionales, determinando la potencialidad de amortiguación

Outer-disk reddening and gas-phase metallicities: The CALIFA connection

Based on observations collected at the German-Spanish Astronomical Center, Calar Alto, jointly operated by the Max-Planck-Institut für Astronomie Heidelberg and the Instituto de Astrofísica de Andalucía (CSIC ).CALIFA Team: et al.We study, for the first time in a statistically significant and well-defined sample, the relation between the outer-disk ionized-gas metallicity gradients and the presence of breaks in the surface brightness profiles of disk galaxies. Sloan Digital Sky Survey (SDSS) g′- and r′-band surface brightness, (g′ - r′) color, and ionized-gas oxygen abundance profiles for 324 galaxies within the Calar Alto Legacy Integral Field Area (CALIFA) survey are used for this purpose. We perform a detailed light-profile classification, finding that 84% of our disks show down- or up-bending profiles (Type II and Type III, respectively), while the remaining 16% are well fitted by one single exponential (Type I). The analysis of the color gradients at both sides of this break shows a U-shaped profile for most Type II galaxies with an average minimum (g′ - r′) color of ∼ 0.5mag and an ionized-gas metallicity flattening associated with it only in the case of low-mass galaxies. Comparatively, more massive systems show a rather uniform negative metallicity gradient. The correlation between metallicity flattening and stellar mass for these systems results in p-values as low as 0.01. Independent of the mechanism having shaped the outer light profiles of these galaxies, stellar migration or a previous episode of star formation in a shrinking star-forming disk, it is clear that the imprint in their ionized-gas metallicity was different for low- and high-mass Type II galaxies. In the case of Type III disks, a positive correlation between the change in color and abundance gradient is found (the null hypothesis is ruled out with a p-value of 0.02), with the outer disks of Type III galaxies with masses ≤10 M′ showing a weak color reddening or even a bluing. This is interpreted as primarily due to a mass downsizing effect on the population of Type III galaxies that recently experienced an enhanced inside-out growth.R. A. Marino is funded by the Spanish program of International Campus of Excellence Moncloa (CEI).We acknowledge support from the Plan Nacional de Investigación y Desarrollo funding programs, AyA2010-15081, AyA2012-30717 and AyA2013-46724P, of Spanish Ministerio de Economía y Competitividad (MINECO). A.G.d.P. acknowledges the support from the FP7 Marie Curie Actions of the European Commission, via the Initial Training Network DAGAL under REA grant agreement PITNGA-2011-289313. C.C.-T. thanks the support of the Spanish Ministerio de Educación, Cultura y Deporte by means of the FPU fellowship program. C.J.W. acknowledges support through the Marie Curie Career Integration Grant 303912. Support for L.G. is provided by the Ministry of Economy, Development, and Tourism’s Millennium Science Initiative through grant IC 120009, awarded to The Millennium Institute of Astrophysics, MAS. L.G. acknowledges support by CONICYT through FONDECYT grant 3140566. S.F.S. thanks the CONACYT-125180 and DGAPA-IA100815 projects for providing him support in this study. J.M.A. acknowledges support from the European Research Council Starting Grant (SEDmorph; P.I. V. Wild). P.P. is supported by FCT through the Investigador FCT Contract No. IF/01220/2013 and POPH/FSE (EC) by FEDER funding through the program COMPETE. He also acknowledges support by FCT under project FCOMP-01-0124-FEDER-029170 (Reference FCT PTDC/FISAST/3214/2012), funded by FCT-MEC (PIDDAC) and FEDER (COMPETE).Peer Reviewe

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements