Cultivos de cobertura: su efecto en el corto plazo sobre la estabilidad estructural evaluada por dos técnicas

Aggregate stability (AS) is a property closely linked to soil fluid movement. AS can be determined by different methods and canbe improved using cover crops (CC), but the short-term effect of this practice has been little studied. The aim of this study wasto evaluate the soil surface aggregate stability of an Argiudoll under no tillage in the Pampas, during the first year after differentCC incorporation. AS was determined by using two laboratory techniques: Le Bissonnais and De Leenheer & De Boodt methods,after incorporating different CC (oat, vetch, wheat, oat + vetch) at two different times: after the CC was chemically dried andafter the subsequent corn crop harvest. A treatment without CC was also evaluated (fallow between summer crops) as a control.The presence of CC roots improved AS significantly compared to the control, while differences among the various CC were alsoobserved. The presence of corn roots and the residual effect of the decomposition of CC stubble left on the ground also had apositive effect on AS. The various pre-treatments applied by the Le Bissonnais method gave different results: fast wetting ofaggregates showed significant differences on AS between the different CC used, whereas slow wetting and mechanical rupturewere more effective than fast wetting showing AS differences over time. The results of the De Leenheer & De Boodt method weremore erratic and less consistent than those obtained by the Le Bissonnais method.La estabilidad de agregados (AS) es una propiedad estrechamente relacionada con el movimiento de los fluidos en el suelo. La AS puede determinarse mediante diferentes métodos y puede evolucionar favorablemente utilizando cultivos de cobertura (CC). Sin embargo, el efecto a corto plazo de esta práctica ha sido poco estudiado. El objetivo de este estudio fue evaluar la estabilidad de los agregados superficiales de un Argiudol bajo siembra directa perteneciente a la región Pampeana, durante el primer año después de incorporar diferentes cultivos de cobertura. La AS se determinó después de incorporar distintos CC (avena, vicia, trigo, avena + vicia) en dos momentos diferentes, al secado de los CC y a la cosecha del cultivo de maíz, utilizando dos técnicas de laboratorio: los métodos de Le Bissonnais y de De Leenheer & De Boodt. También se evaluó un tratamiento sin CC (barbecho químico entre cultivos de verano) como control. La presencia de raíces de los CC mejoró significativamente la AS en comparación con el control, mientras que también se observaron diferencias entre los diversos CC. El efecto de las raíces del maíz y el debido a la descomposición de los rastrojos de los CC dejados en la superficie del suelo, también tuvieron un efecto positivo sobre la AS. Los diversos pre-tratamientos del método de Le Bissonnais dieron resultados diferentes: la humectación rápida de los agregados mostró diferencias significativas en la AS entre los diferentes CC utilizados, mientras que la humectación lenta y la disgregación mecánica fueron más efectivos que la humectación rápida para mostrar las diferencias de la AS en el tiempo. Los resultados del método De Leenheer & De Boodt fueron más erráticos y menos consistentes que los obtenidos por el método de Le Bissonnais.Fil: Castiglioni, Mario Guillermo. Universidad de Buenos Aires. Facultad de Agronomia. Departamento de Ingenieria Agricola y Uso de la Tierra. Cátedra de Manejo y Conservación de Suelo; ArgentinaFil: Behrends Kraemer, Filipe. Universidad de Buenos Aires. Facultad de Agronomia. Departamento de Ingenieria Agricola y Uso de la Tierra. Cátedra de Manejo y Conservación de Suelo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Analysis of nifH-RNA reveals phylotypes related to Geobacter and Cyanobacteria as important functional components of the N2-fixing community depending on depth and agricultural use of soil

In this survey, a total of 80 787 reads and 28 171 unique NifH protein sequences were retrieved from soil RNA. This dataset extends our knowledge about the structure and diversity of the functional diazotrophic communities in agricultural soils from Argentinean Pampas. Operational taxonomic unit (OTU)-based analyses showed that nifH phylotypes related to Geobacter and Anaeromyxobacter (44.8%), Rhizobiales (29%), Cyanobacteria (16.7%), and Verrucomicrobiales (8%) are key microbial components of N2 fixation in soils associated with no-till management and soil depth. In addition, quantification of nifH gene copies related to Geobacter and Cyanobacteria revealed that these groups are abundant in soils under maize-soybean rotation and soybean monoculture, respectively. The correlation of physicochemical soil parameters with the diazotrophic diversity and composition showed that soil stability and organic carbon might contribute to the functional signatures of particular nifH phylotypes in fields under no-till management. Because crop production relies on soil-borne microorganism´s activities, such as free N2 fixation, the information provided by our study on the diazotrophic population dynamics, associated with the edaphic properties and land-use practices, represents a major contribution to gain insight into soil biology, in which functionally active components are identified.Fil: Calderoli, Priscila Anabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Biotecnología y Biología Molecular. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Biotecnología y Biología Molecular; ArgentinaFil: Collavino, Mónica Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; ArgentinaFil: Behrends Kraemer, Filipe. Universidad de Buenos Aires. Facultad de Agronomía; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Recursos Naturales. Instituto de Suelos; ArgentinaFil: Morrás, Héctor José María. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Recursos Naturales. Instituto de Suelos; ArgentinaFil: Aguilar, Orlando Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Biotecnología y Biología Molecular. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Biotecnología y Biología Molecular; Argentin

N-acetylgalactosamine 4-sulfate 6-O-sulfotransferase expression during early mouse embryonic development

N-acetylgalactosamine 4-sulfate 6-O-sulfotransferase (GalNAc4S-6ST) is an enzyme which is known to help build up the GlcA beta 1-3GalNAc(4,6-bisSO(4)) unit of chondroitin sulfate E (CSE). This enzymatic activity has been reported in squid cartilage and in human serum, but has never been reported as an enzyme required during early mouse development. On the other hand, CSE has been shown to bind with strong affinity to Midkine (MK). The latter is a heparin-binding growth factor which has been found to play important regulatory roles in differentiation and morphogenesis during mouse embryonic development. We have analyzed the expression pattern of the GalNAc4S-6ST gene during early mouse embryonic development by whole mount in situ hybridization. The results show that GalNAc4S-6ST is differentially expressed in the anterior visceral ectoderm at stage E5.5 and later becomes restricted to the embryonic endoderm, especially in the prospective midgut region. During the turning process, expression of GalNAc4S-6ST gene is detected in the forebrain, branchial arches, across the gut tube (hindgut, midgut and foregut diverticulum), in the vitelline veins and artery and in the splanchnopleure layer. These results open the possibility of a role for GalNAc4S-6ST during early mouse development

Stabilization of unilamellar catanionic vesicles induced by \u3b2-cyclodextrins: A strategy for a tunable drug delivery depot

The limited stability of catanionic vesicles has discouraged their wide use for encapsulation and controlled release of active substances. Their structure can easily break down to form lamellar phases, micelles or rearrange into multilamellar vesicles, as a consequence of small changes in their composition. However, despite the limited stability, catanionic vesicles possess an attractive architecture, which is able to efficiently encapsulate both hydrophobic and hydrophilic molecules. Therefore, improving the stability of the vesicles, as well as the control on unilamellar structures, are prerequisites for their wider application range. This study focuses on the impact of \u3b2-cyclodextrins for the stabilization of SDS/CTAB catanionic vesicles. Molar ratio and sample preparation procedures have been investigated to evaluate the temperature stability of catanionic vesicles. Diffusion and spectroscopic techniques evidenced that when \u3b2-cyclodextrins are added, unilamellar structures are stabilized above the multilamellar-unilamellar vesicles critical temperature. The results evidence encouraging perspectives for the use of vesicular nanoreservoirs for drug depot applications

Saturated hydraulic conductivity determined with different procedures in soils with high soil water content

La conductividad hidráulica saturada (Ks) ejerce una fuerte influencia sobre la partición de la lluvia en infiltración y escurrimiento. Una correcta estimación de esta propiedad es importante para poder modelar de manera realista los procesos hidrológicos y de erosión que ocurren en el suelo. Los objetivos del presente trabajo fueron: Comparar los resultados de Ks obtenidos en suelos bajo agricultura con alta humedad inicial y ubicados en dos posiciones del paisaje (loma y media loma), determinados mediante distintos procedimientos de campo y de laboratorio, analizando a su vez la incidencia que tienen otras propiedades físicas edáficas sobre dichos resultados. En dos años sucesivos se determinó la Ks por distintas técnicas de campo (doble anillo, simulador de lluvia, permeámetro de Guelph y de disco) y de laboratorio, sobre un Argiudol de la Pampa Ondulada bajo siembradirecta. Se compararon los resultados de Ks generados por los distintos procedimientos, como también si existió algún grado de vinculación entre los mismos y con otras propiedades físicas edáficas. Se estudió además la variabilidad de los resultados obtenidos. El suelo sobre el que se trabajó presentó un contenido inicial de humedad alto y una condición física pobre. El contenido hídrico inicial solo influyó sobre los resultados de Ks aportados por el doble anillo y el simulador de lluvia, mientras que la densidad aparente lo hizo sobre los generados con elpermeámetro de Guelph y por la técnica de laboratorio. Las diferencias encontradas en la Ks determinada por las distintas técnicas, respondieron fundamentalmente al tipo de flujo dominante: vertical (doble anillo y simulador de lluvia), tridimensional (permeámetro de Guelph y de disco) y libre en la parte inferior del suelo (laboratorio), aumentando en ese mismo orden el valor de Ks observado.Saturated hydraulic conductivity (Ks) has a strong influence on the partition of the rain in infiltration and runoff. A correct value of this property is important to estimate in a real way the hydrological and erosion processes. The aim of the present work was: To compare the results of Ks obtained in soils under agriculture with high initial water content and located in two different positions of the landscape, determined by different field and laboratory procedures, analyzing in turn the incidence of other soil physical properties over these results. In two successive years, the Ks was determined by different field techniques (double ring, rain simulator, Guelph and disk permeameter) and a laboratory practice, on an Argiudol of Rolling Pampa under no tillage. The results of Ks generated by the different procedures were compared, as well as if there was some link between them and with other soil physical properties. The Ks variability was also studied. The soil presented high initial water content and a poor physical condition. The initial water content only influenced the results of Ks obtained with the double ring and with the rain simulator, while bulk density affected those generated with Guelph permeameter and by the laboratory technique. The differences found in Ks determined by the several techniques were linked to the dominant flow type: vertical (double ring and rain simulator), three-dimensional (Guelph and disk permeameter) and free in the lower part of the soil (laboratory), increasing in the same order the value of Ks observed.Fil: Castiglioni, Mario Guillermo. Universidad de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Behrends Kraemer, Filipe. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Marquez Molina, John Jairo. Universidad de Buenos Aires. Facultad de Agronomía; Argentin

Overview of Cosmology with the SKA

Advancing Astrophysics with the Square Kilometre Array June 8-13, 2014 Giardini Naxos, ItalyThe new frontier of cosmology will be led by three-dimensional surveys of the large-scale structure of the Universe. Based on its all-sky surveys and redshift depth, the SKA is destined to revolutionize cosmology, in combination with future optical/ infrared surveys such as Euclid and LSST. Furthermore, we will not have to wait for the full deployment of the SKA in order to see transformational science. In the first phase of deployment (SKA1), all-sky HI intensity mapping surveys and all-sky continuum surveys are forecast to be at the forefront on the major questions of cosmology. We give a broad overview of the major contributions predicted for the SKA. The SKA will not only deliver precision cosmology – it will also probe the foundations of the standard model and open the door to new discoveries on large-scale features of the Universe

Cosmic Dawn and Epoch of Reionization Foreground Removal with the SKA

The exceptional sensitivity of the SKA will allow observations of the Cosmic Dawn and Epoch of Reionization (CD/EoR) in unprecedented detail, both spectrally and spatially. This wealth of information is buried under Galactic and extragalactic foregrounds, which must be removed accurately and precisely in order to reveal the cosmological signal. This problem has been addressed already for the previous generation of radio telescopes, but the application to SKA is different in many aspects. In this chapter we summarise the contributions to the field of foreground removal in the context of high redshift and high sensitivity 21-cm measurements. We use a state-of-the-art simulation of the SKA Phase 1 observations complete with cosmological signal, foregrounds and frequency-dependent instrumental effects to test both parametric and non-parametric foreground removal methods. We compare the recovered cosmological signal using several different statistics and explore one of the most exciting possibilities with the SKA --- imaging of the ionized bubbles. We find that with current methods it is possible to remove the foregrounds with great accuracy and to get impressive power spectra and images of the cosmological signal. The frequency-dependent PSF of the instrument complicates this recovery, so we resort to splitting the observation bandwidth into smaller segments, each of a common resolution. If the foregrounds are allowed a random variation from the smooth power law along the line of sight, methods exploiting the smoothness of foregrounds or a parametrization of their behaviour are challenged much more than non-parametric ones. However, we show that correction techniques can be implemented to restore the performances of parametric approaches, as long as the first-order approximation of a power law stands.Comment: Accepted for publication in the SKA Science Book 'Advancing Astrophysics with the Square Kilometre Array', to appear in 201