Dissolved organic matter in freshwater environments: Effects on ecosystems, transfer and transformation

La materia orgánica disuelta en los ambientes dulceacuícolas: Efectos en los ecosistemas, transferencia y transformación. Las aguas continentales vinculan los sistemas terrestres, la atmósfera y los océanos a través del ciclo biogeoquímico del carbono. Los arroyos, ríos y lagos son sistemas extremadamente activos para el transporte, transformación y almacenamiento de grandes cantidades de carbono de origen terrestre, que se encuentra principalmente en forma de materia orgánica disuelta (MOD). Este complejo heterogéneo de sustancias posee un rol central en los cuerpos de agua. La MOD influye en la ecología de los sistemas acuáticos ya que atenúa la radiación solar, regula el pH, interviene en el transporte de nutrientes y metales, y sustenta las tramas tróficas microbianas. La transferencia de MOD entre sistemas, su concentración y calidad, están controlados por factores climáticos, físico-químicos y biológicos. Debido a ello, su estudio permite comprender y predecir cambios ambientales naturales y antropogénicos. En este artículo se describe la importancia de la MOD en sistemas dulceacuícolas, detallando sus propiedades químicas, interacciones y transformaciones.Dissolved organic matter in freshwater environments: Effects on ecosystems, transfer and transformation. Inland waters connect terrestrial systems, atmosphere and oceans through the biogeochemical carbon cycle. The streams, rivers and lakes are extremely active systems for the transport, transformation and storage of large amounts of terrestrial origin carbon, which is found mainly in the form of dissolved organic matter (DOM). This heterogeneous complex of substances plays a key role in water bodies. DOM influences several ecological properties of aquatic ecosystems, attenuating the solar radiation, regulating the pH, mediating the transport of nutrients, metals and, ultimately supporting microbial food webs. The transference of DOM among ecosystems, its magnitude and quality are controlled by several factors including, climate, and physic-chemical and biological ones. Therefore, its study allows us to understand and predict natural and anthropogenic environmental changes. This article describes the importance of DOM in freshwater systems, detailing its chemical properties, interactions and transformations.Fil: García, Roberto Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentin

Instruments that revolutionized the science: The history of the spectrophotometer

La aparición del espectrofotómetro creado por Arnold Beckman en 1941 revolucionó el mundo de la biociencia. La cotidianidad actual de este instrumento ha conducido al desconocimiento de los alcances de su tecnología. En esta investigación se reivindica al espectrofotómetro y su creador como importantes generadores del desarrollo de la ciencia de los últimos 70 años. En este artículo trazamos la evolución de este importante instrumento científico desde su origen hasta las perspectivas a futuro. En este recorrido por su historia, se incluyen además las nociones básicas de su funcionamiento, su aplicación en diversas áreas y sus aportes más significativos.The arrival of the spectrophotom-eter created by Arnold Beckman in 1941 revolutionized the world of bioscience. The currently ordinariness of this instru-ment has led to ignorance about the reach of its technology. The spectrophotometer and its creator are vindicated in this research as important generators of the development of science in the last 70 years. In this article we trace the evolution of this important scientific instrument from its origin to its future prospects. In this journey into its history, are also included the basic conceptsof its functioning, its application in several areas and its most significant contributions.Fil: García, Roberto Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentin

Mapeamento geológico de rochas ígneas: Um estudo de caso na região de Garzón, Cordilheira Oriental dos Andes Colombianos

Granitos Jurássicos (sensu lato) e rochas relacionadas são as rochas mais comuns que afloram na Cordilheira Oriental da Colômbia no norte dos Andes. Apresenta-se um mapa e uma caracterização detalhada da diversidade petrográfica dos granitos jurássicos e rochas subvulcânicas relacionadas que afloram na região de Garzón, extremo sul da Cordilheira Oriental. Elaboraram-se novos mapas geológicos para os Maciços Plutônicos de Algeciras e Altamira, baseados nos conceitos descritivos de fácies e associações de fácies petrográficas, petrografia detalhada e caracterização mineralógica dos tipos de granitos observados. Oito fácies petrográficas ou associações de fácies plutônicas e três subvulcânicas foram reconhecidas e mapeadas no Maciço Plutônico de Algeciras e outras cinco no Maciço Plutônico de Altamira. Hornblenda biotita granitos (sieno- e monzogranitos) predominam no primeiro maciço, enquanto leucogranitos são predominantes no segundo. Um padrão zonado de distribuição de fácies foi mapeado no Maciço Plutônico de Algeciras. Corpos menores e/ou diques de pórfiros félsicos (dacitos e riolitos) e diques máficos-intermediários sin-plutônicos (principalmente microdioritos) cortam as principais rochas plutônicas nos dois maciços. Características geológicas e petrográficas (e.g. texturas micrográficas) sugerem níveis de colocação relativamente rasos para as rochas plutônicas e soerguimento e erosão levemente mais acentuados na região norte da área estudada. Estruturas planares de deformação em estado sólido e a orientação dos diques mapeados são compatíveis com movimentações dextrais do Sistema de Falhas de Algeciras, orientado SSW-NNE, em um regime transpressivo, associado com importante compressão e convergência oblíqua durante o Jurássico.Jurassic granites (sensu lato) and related rocks are the most abundant rocks cropping out in the Eastern Cordillera of Colombia in the northern Andes. We present an attempt to map and characterize in detail the petrographic diversity of the Jurassic granites and related subvolcanic rocks emplaced in the Garzón region, southernmost the Eastern Cordillera. We also provide new geological maps for the Algeciras and Altamira Plutonic Massifs based on descriptive concepts of the petrographic facies and facies associations and detailed petrographic and mineralogical characterizations of the observed granite types. Eight plutonic and three subvolcanic petrographic facies or facies associations were mapped in the Algeciras Plutonic Massif, and another five in the Altamira Plutonic Massif. Hornblende biotite granites (syeno- and monzogranites) are the main plutonic types constituting the first massif, while leucogranites prevail in the second massif; a zoned facies distribution was mapped in the Algeciras Plutonic Massif. Felsic porphyries (dacite and rhyolite) crop out as minor irregular intrusive bodies or dikes and mafic-intermediate syn-plutonic dikes (mostly microdiorites) cross cut the main plutonic rocks in both massifs. Geological and petrographic characteristics (e.g. micrographic textures) suggest relatively shallow emplacement levels for the plutonic rocks as well as slightly high uplift and erosion rates at the north of the studied area. Local penetrative solid-state planar structures and dike orientations conform with dextral strike-slip movements along the SSW-NNE trending Algeciras Fault System in a transpressional regime associated with a major compressive and oblique convergence in Jurassic ages

Parabroteas: El pequeño gigante de la Patagonia

Numerosos humedales patagónicos albergan al copépodo de agua dulce más grande del mundo. Conozca la biología de este voraz invertebrado y su rol en las redes alimentarias de lagos y lagunas.Fil: García, Roberto Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación En Biodiversidad y Medioambiente; ArgentinaFil: Reissig, Mariana. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación en Biodiversidad y Medioambiente; ArgentinaFil: Dieguez, Maria del Carmen. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación En Biodiversidad y Medioambiente; Argentin

A new near-IR window of low extinction in the Galactic plane

Reproduced with permission from Astronomy & Astrophysics. © 2018 ESO. Comments: 6 pages, 6 figures. Accepted for publication in Astronomy & AstrophysicsAims. The windows of low extinction in the Milky Way (MW) plane are rare but important because they enable us to place structural constraints on the opposite side of the Galaxy, which has hither to been done rarely. Methods. We use the near-infrared (near-IR) images of the VISTA Variables in the Vía Láctea (VVV) Survey to build extinction maps and to identify low extinction windows towards the Southern Galactic plane. Here we report the discovery of VVV WIN 1713-3939, a very interesting window with relatively uniform and low extinction conveniently placed very close to the Galactic plane. Results. The new window of roughly 30 arcmin diameter is located at Galactic coordinates (l, b) = (347.4, -0.4) deg. We analyse the VVV near-IR colour-magnitude diagrams in this window. The mean total near-IR extinction and reddening values measured for this window are A Ks = 0.46 and E(J - K s) = 0.95. The red clump giants within the window show a bimodal magnitude distribution in the K s band, with peaks at K s = 14.1 and 14.8 mag, corresponding to mean distances of D = 11.0 ± 2.4 and 14.8 ± 3.6 kpc, respectively. We discuss the origin of these red clump overdensities within the context of the MW disk structure.Peer reviewe

Centrifugal compressor influence on condensation due to Long Route-Exhaust Gas Recirculation mixing

[EN] State of the art techniques for reducing pollutant emission in internal combustion engines often require local flow assessment, specially in the air management field. This work addresses the interaction between a turbo- charger compressor and the 3-way long-route EGR joint, where exhaust gases of the combustion are mixed with fresh air. A validated methodology for compressor simulation is combined with a validated condensation model for this work. Numerical simulations of two different working points with three flap positions are conducted. The influence of these operating conditions on the flow field is evaluated. Particularly, there is a connection between the mixing of both steams and the generation of water condensates, responsible for the erosion of the impeller and the loss of compressor efficiency. Moreover, neglecting the impact of the compressor presence on the condensation production is shown to be of low magnitude, so that simulations without the compressor are regarded as accurate, thus reducing the computational effort by two orders of magnitude.Daniel Taxi is partially supported through contract FPI-S2-2015-1095 of Programa de Apoyo para la Investigacion y Desarrollo (PAID) of Universitat Politecnica de Valencia.Galindo, J.; Navarro, R.; Tarí, D.; García -Olivas, G. (2018). Centrifugal compressor influence on condensation due to Long Route-Exhaust Gas Recirculation mixing. Applied Thermal Engineering. 144:901-909. https://doi.org/10.1016/j.applthermaleng.2018.09.005S90190914

Record of parasitic oomycetes on neotropical copepods in aquatic environments of Northwestern Patagonia (Argentina)

Aim: Oomycetes are one of the most widespread and destructive parasitic groups in the world. The first infection of oomycetes on copepod Parabroteas sarsi Daday 1901 was recently recorded in America. Oomycetes infection on this species makes their eggs unviable and could differentially affect the survival of females. The aim of this study was to track the incidence of oomycetes in two populations of P. sarsi. Methods: Two Patagonian ponds were monitored during spring-summer of 2014-2018, measuring environmental variables and the prevalence of oomycete infections on P. sarsi populations. Taxonomic determination of the oomycetes was performed in laboratory. Sex ratios also were recorded in each survey. Results: The presence of Aphanomyces ovidestruens Gicklhorn 1923 and Pythium flevoense Van der Plaats-Niterink 1972 was detected in females of P. sarsi in both ponds. We observed a decrease in the parasite prevalence over time, from ~25% (assessed on the total number of adults) to almost disappear completely. Besides, a lower proportion of females than males were observed in samples with high prevalence of parasitism. No temperature differences were found during the sampling years and the monthly temperatures between the maximum and minimum prevalences were similar. Conclusions: Our study presents a new record of oomycetes parasitizing copepods in America. Temperature can play a key role in the dynamics of parasite species, but in our study this variable not affected the incidence of the infection. However, other variables could be affect the pattern of the infection such as the presence of predators of oomycetes spores (cladocerans). The lower females proportion when the infection was higher, could support the idea of differential sex/mortality induced by the infection. Recording and identification of parasites is a critical starting point for wildlife management, which will provide an early warning to prevent the spread of harmful parasites such as oomycetes.Objetivo: Os oomicetos são um dos grupos parasitários mais difundidos e destrutivos do mundo. A primeira infecção de oomicetos no copépode Parabroteas sarsi Daday 1901 foi recentemente registrada na América. A infecção por Oomycetes nesta espécie torna os seus ovos inviáveis e pode afetar diferentemente a sobrevivência das fêmeas. O objetivo deste estudo foi rastrear a incidência de oomicetos em duas populações de P. sarsi. Métodos: Duas poças na patagônia foram monitoradas durante a primavera-verão de 2014-2018, medindo variáveis ambientais e a prevalência de infecções por oomicetos em populações de P. sarsi. A determinação taxonômica dos oomicetos foi realizada em laboratório. As proporções de sexo também foram registradas em cada pesquisa. Resultados: A presença de Aphanomyces ovidestruens Gicklhorn 1923 e Pythium flevoense Van der Plaats-Niterink 1972 foi detectada em fêmeas de P. sarsi em ambas as poças. Observamos uma diminuição na prevalência de parasita ao longo do tempo, com uma redução que foi de aproximadamente 25% (considerando o número total de adultos) até próximo de desaparecer completamente. Além disso, uma proporção menor de fêmeas do que de machos foi observada em amostras com alta incidência de parasitismo. Não foram encontradas diferenças de temperatura durante os anos de amostragem e as temperaturas mensais entre as prevalências máxima e mínima foram semelhantes. Conclusão: Nosso estudo apresenta um novo registro de parasitismo por oomicetos em copépodes na América. A temperatura pode desempenhar um papel fundamental na dinâmica das espécies parasitárias, mas em nosso estudo esta variável não afetou a incidência da infecção. No entanto, outras variáveis podem afetar o padrão da infecção, como a presença de predadores de esporos de oomicetos (cladóceros). A menor proporção de fêmeas quando a infecção foi maior indicam mortalidade diferencial por sexo induzida pela infecção. O registo e identificação de parasitas é um ponto de partida crítico para a gestão da vida selvagem, o que proporcionará um alerta precoce para prevenir a propagação de parasitas nocivos como os oomicetos.Fil: García, Roberto Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Jara, Fabian Gaston. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Steciow, Mónica Mirta. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Botánica Spegazzini; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentin

Integral field spectroscopy of HII regions in M33

Integral field spectroscopy (IFS) is presented for star forming regions in M33. A central area of 300 x 500 pc^2 and the external HII region IC 132, at a galactocentric distance {\sim} 19arcmin (4.69 kpc) were observed with the Potsdam Multi Aperture Spectrophotometer (PMAS) instrument at the 3.5 m telescope of the Calar Alto Hispano- Alem\'an observatory (CAHA). The spectral coverage goes from 3600 A to 1{\mu}m to include from [OII]{\lambda}3727 A to the near infrared lines required for deriving sulphur electron temperature and abundance diagnostics. Local conditions within individual HII regions are presented in the form of emission line fluxes and physical conditions for each spatial resolution element (spaxel) and for segments with similar H{\alpha} surface brightness. A clear dichotomy is observed when comparing the central to outer disc HII regions. While the external HII region has higher electron temperature plus larger H{\beta} equivalent width, size and excitation, the central region has higher extinction and metal content. The dichotomy extends to the BPT diagnostic diagrams that show two orthogonal broad distributions of points. By comparing with pseudo-3D photoionization models we conclude that the bulk observed differences are probably related to a different ionization parameter and metallicity. Wolf-Rayet features are detected in IC 132, and resolved into two concentrations whose integrated spectra were used to estimate the characteristic number of WR stars. No WR features were detected in the central HII regions despite their higher metallicity.Comment: 72 pages, 37 figure

Large D gravity and low D strings

We show that in the limit of a large number of dimensions a wide class of nonextremal neutral black holes has a universal near-horizon limit. The limiting geometry is the two-dimensional black hole of string theory with a two-dimensional target space. Its conformal symmetry explains the properties of massless scalars found recently in the large-D limit. For black branes with string charges, the near-horizon geometry is that of the three-dimensional black strings of Horne and Horowitz. The analogies between the α′ expansion in string theory and the large-D expansion in gravity suggest a possible effective string description of the large-D limit of black holes. We comment on applications to several subjects, in particular to the problem of critical collapse