Árbol de decisión para diagnosticar la capacidad productiva de suelos de la región pampeana.

Los suelos constituyen un continuum a través de la superficie terrestre. Cada combinación específica de paisaje, clima, material parental, proceso de meteorización, vegetación y manejo determina diferentes unidades de suelo. En suelos agrícolas, la distinción entre diferentes unidades de suelo suele ser muy compleja y requiere experiencia de campo. De hecho, tanto estudiantes de grado en las Universidades como profesionales poseen dificultades para diagnosticar la aptitud de los suelos para la producción de cultivos. Con el objeto de facilitar la identificación de la aptitud productiva de las diferentes unidades de suelo, se ha desarrollado un árbol de decisión o cursograma, con énfasis en los suelos pampeanos. La Región Pampeana argentina es la más productiva en términos agrícolas y varios de sus suelos son considerados dentro de los más fértiles del planeta. Sin embargo, éstos se encuentran distribuidos en el paisaje formando un intrincado patrón con otros menos productivos.El árbol de decisión fue organizado en dos pasos sucesivos (1: Paisaje; y 2: Perfil del suelo), que conducen al paso final 3: Nivel de aptitud para cultivos. El análisis de paisaje incluye la frecuencia de anegamientos, la presencia de suelos arenosos y la pendiente. El análisis del perfil de suelo comienza con la identificación de las principales limitantes: salinidad,sodicidad, anegamiento, impedancias mecánicas, y el espesor del horizonte superficial. Esperamos que esta nueva herramienta, diseñada para estudiantes de grado y profesionales pueda ser utilizada para hacer un primer diagnóstico de suelos.Fil: Rubio, Gerardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Parque Centenario. Instituto de Investigaciones en Biociencias Agricolas y Ambientales; Argentina;Fil: Taboada, Miguel Angel. Instituto Nacional de Tecnología Agropecuaria. Centro Nacional de Inv. Agropecuarias. Centro de Investigacionesde Recursos Naturales; Argentina

Historia cómica de España

Entre los autores figuran Sinesio Delgado y Miguel Ramos CarriónCopia digital. Valladolid : Junta de Castilla y León. Consejería de Cultura y Turismo, 2009-201

Contribution of biological nitrogen fixation to N2O emission from soil under soybean

El óxido nitroso (N2 O) es el principal gas de efecto invernadero emitido desde el sector agrícola y su producción biológica en los suelos se genera por dos vías, la nitrificación y la desnitrificación. Recientemente el Panel Intergubernamental para el Cambio Climático (IPCC) ha excluido de sus directrices de inventario a la Fijación Biológica del Nitrógeno (FBN) como fuente de emisión de N2 O por los cultivos leguminosos, debido a la falta de evidencia segura sobre la existencia de estas emisiones. Pese a ello, en la actualidad se sigue discutiendo sobre la emisión de N2 O real emitida desde los cultivos leguminosos a campo, en especial en soja que es el principal producto producido por la Argentina y fuente de biodiesel. La influencia de FBN sobre la emisión de N2 O puede probarse utilizando variedades de soja no nodulante. El objetivo de este trabajo fue comparar y analizar la emisión de N2 O desde suelos con cultivos de soja de variedad nodulante y no nodulante, con el fin de evaluar la influencia real del cultivo sobre la emisión de N2 O a campo. Las muestras de gas fueron colectadas con cámaras cerradas no ventiladas. La emisión de N2 O varió entre -9 y 15 μg N-N2 O m-2 h-1. Sólo se observó diferencia significativa en la emisión de N2 O entre los tratamientos en la última fecha de muestreo (no nodulante > nodulante). La emisión de N2 O se relacionó positivamente con la concentración de N-NO3 - del suelo y con el espacio poroso lleno de agua (EPLLA). Esta ausencia de diferencia significativa en los valores de emisión de N2 O entre los tratamientos, indica que la soja nodulante no emitió mayor cantidad de N2 O que la no nodulante, revelando que la presencia de nódulos fijadores per se no afectó la cantidad de N2 O emitida durante el crecimiento del cultivo de soja. Estos resultados avalan lo establecido por las últimas directrices de IPCC 2006 y ponen en cuestión otras metodologías de inventario que cargan más emisión de N2 O a los cultivos de soja. Los resultados del presente estudio muestran que la FBN sólo causó un ligero impacto en la emisión de N2 O, en concordancia con las últimas directrices del IPCC del 2006 para los inventarios de GEI.Nitrous oxide (N2 O) is the main greenhouse gas (GHG) emitted from agricultural soils as a by-pass product of nitrification and denitrification processes. The Intergovernmental Panel on Climate Change (IPCC) excluded from its GHG inventory guidelines in 2006 the Nitrogen Biological Fixation (NBF) as a source of N2 O emissions by crop legumes, due to the lack of solid scientific evidenceon the existence of these emissions. However, at present the actual amount of N2 O emissions by crop legumes in the field is still under investigation, with special emphasis on soybeans which are is the main commodity produced by Argentina and a main biodiesel source. The influence of NBF on N2 O emissions can be tested using nonnodulating soybean varieties. This study aims to compare and analyse N2 O emissions from nodulating and non-nodulating soybean varieties in order to clarify the actual influence of this commodity on field GHG emissions. Gas samples were collected from closed non-vented chambers. N2 O emissions ranged from -9 to +15 μg N-N2 O m-2 h-1 and only in the last sampling date, values differed significantly between treatments (non-nodulating > nodulating soybean). N2 O emissions were positively related with soil N-NO3 concentration and soil water-filled pore space (WFPS). Results show that in this field study, NBF caused only a slight impact on N2 O emissions. These results agree with the latest IPCC guidelines in 2006 for GHG inventories.Fil: Cosentino, Vanina Rosa Noemi. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Recursos Naturales. Instituto de Suelos; Argentina. Universidad de Buenos Aires. Facultad de Agronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Brutti, Lucrecia Noemí. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Recursos Naturales. Instituto de Suelos; Argentina. Universidad de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Civeira, Gabriela. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Recursos Naturales. Instituto de Suelos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Taboada, Miguel Angel. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Recursos Naturales. Instituto de Suelos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Stress compensation by gap monolayers for stacked InAs/GaAs quantum dots solar cells

In this work we report the stacking of 10 and 50 InAs quantum dots layers using 2 monolayers of GaP for stress compensation and a stack period of 18 nm on GaAs (001) substrates. Very good structural and optical quality is found in both samples. Vertical alignment of the dots is observed by transmission electron microscopy suggesting the existence of residual stress around them. Photocurrent measurements show light absorption up to 1.2 μm in the nanostructures together with a reduction in the blue response of the device. As a result of the phosphorus incorporation in the barriers, a very high thermal activation energy (431 meV) has also been obtained for the quantum dot emission

Conservation préventive pour tous: une guide illustré

Bibliografía: p. 214-12

Non-residential pedestrian access to transit systems: a GIS modeling application

The success of a city’s urban transit system relies on the efficacy of its pedestrian infrastructure. A functional and access-oriented pedestrian network translates into safer pedestrian travel, increased demand in transit ridership, increases in commerce patronage, and reduced motorized travel (i.e., less congestion, and less vehicle emissions). Prioritization and allocation of sidewalk construction improvements are not always done in conjunction with transit service provisions. As a result, potential destinations are left inaccessible to pedestrians using the transit system. This study is motivated by concurrent research involving sidewalk improvement prioritization methods, within the scope of home-based work pedestrian transit trips. This study focuses on connecting transit to nonresidential origins and destinations. The main methodological approach developed relied on a gravity-based modeling framework. The method was applied to the City of Knoxville and the Knoxville Area Transit system. Land use, transit network configuration, and road network data for Knoxville and Knox County were used to estimate walking paths from transit stops to nonresidential destinations. These walking segments were ranked per a gravity-based potential attraction measure, and were compared to the existing sidewalk infrastructure in order to identify segments of network improvement opportunities. This study presents a methodology that can be used by transportation planners and decision makers for sidewalk improvement prioritization. Identifying key walking segments is an essential preliminary step to developing a pedestrian infrastructure that can effectively support a transit system, thus boosting transit ridership, and improving safety and access for riders

Cannabinoid receptor CB2 drives HER2 pro-oncogenic signaling in breast cancer

Pharmacological activation of cannabinoid receptors elicits antitumoral responses in different models of cancer. However, the biological role of these receptors in tumor physio-pathology is still unknown. We analyzed CB2 cannabinoid receptor protein expression in two series of 166 and 483 breast tumor samples operated in the University Hospitals of Kiel, Tübingen and Freiburg between 1997 and 2010. CB2 mRNA expression was also analyzed in previously published DNA microarray datasets. The role of CB2 in oncogenesis was studied by generating a mouse line that expresses the HER2 rat ortholog (neu) and lacks CB2, and by a variety of biochemical and cell biology approaches in human breast cancer cells in culture and in vivo, upon modulation of CB2 expression by si/shRNAs and overexpression plasmids. CB2-HER2 molecular interaction was studied by co-localization, coimmunoprecipitation and proximity ligation assays. We show an association between elevated CB2 expression in HER2+ breast tumors and poor patient prognosis. We also demonstrate that genetic inactivation of CB2 impairs tumor generation and progression in MMTV-neu mice. Moreover, we show that HER2 upregulates CB2 expression by activating the transcription factor ELK1 via the ERK cascade, and that an increased CB2 expression activates the HER2 prooncogenic signaling machinery at the level of the tyrosine kinase c-SRC. Finally, HER2 and CB2 form heteromers in cancer cells. Our findings reveal an unprecedented role of CB2 as a pivotal regulator of HER2 pro-oncogenic signaling in breast cancer, and suggest that CB2 may be a biomarker with prognostic value in these tumors

Fertilizer use soil health and agricultural sustainability

Due to the growing population and consequent pressure of use, agricultural soils must maintain adequate levels of quantity and quality to produce food, fiber, and energy, without falling victim to a negative impact on their balance of nutrients, health, or their ability to function. The use of mineral fertilizers has long been a key tool to offset nutrient outputs and thus achieve increased yields [1–4]. Fertilizer application is believed to have been responsible for at least 50% increase in crop yield in the 20th century [5,6]. According to [5], average corn yields would decline by 40 percent without nitrogen (N) fertilizer application, while long-term studies confirmed a 40–57 percent yield decline in wheat without fertilizer application. Yousaf et al. [6] reported a 19–41% yield increase in rice, and a 61–76% increase in rapeseed with the combined application of NPK fertilizers. However, due to the inappropriate use of mineral fertilizers (i.e., when used in both excess or deficiency), mostly concerning nitrogenous and phosphate, many productive soils have been thwarted in their ability to function, as shown not only by chemical indicators but also by physical and biological ones. Thus, improper fertilizing technology might have a negative effect on soil health and soil-related ecosystem services. Imbalanced use of chemical fertilizers can alter soil pH, and increase pests attack, acidification, and soil crust, which results in a decrease in soil organic carbon and useful organisms, stunting plant growth and yield, and even leading to the emission of greenhouse gases [7,8]. Soil health is defined as the capacity of soil to function as a vital living system, within ecosystem and land-use boundaries, to sustain plant and animal health and productivity, and maintain or improve water and air quality. A major challenge for agricultural sustainability is to conserve ecosystem service delivery while optimizing agricultural yields. This Special Issue addresses the task to find a balance between increasing yields using conventional and novel fertilizers, and the maintenance of soil and environmental health as a basis for the sustainable intensification of the agricultural sector. The purpose of this issue was to provide new knowledge on fertilizer use, soil health, and agricultural sustainability. We received a total of 13 papers that provided interesting and innovative information. Five of them [9–13] were works on basic studies on the status of nutrients. These studies were based on the reviews of published works, or on experiments under controlled conditions (greenhouse and incubation) referring to nitrogen losses due to volatilization, leaching, denitrification, the distribution of nutrients, the combined or integrated use of mineral and organic fertilizers, bio-based nitrogen, or new findings in sulfur, a largely low-attended nutrient.Fil: Krasilnikov, Pavel. Lomonosov Moscow State University. Department of Soil Geography; RusiaFil: Taboada, Miguel Angel. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Suelos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Amanullah. The University of Agriculture. Faculty of Crop Production Sciences. Department of Agronomy; Paquistá