Influence of conservation tillage and soil water content on crop yield in dryland compacted alfisol of Central Chile

Chilean dryland areas of the Mediterranean climate region are characterized by highly degraded and compacted soils, which require the use of conservation tillage systems to mitigate water erosion as well as to improve soil water storage. An oat (Avena sativa L. cv. Supernova-INIA) - wheat (Triticum aestivum L. cv. Pandora-INIA) crop rotation was established under the following conservation systems: no tillage (Nt), Nt + contour plowing (Nt+Cp), Nt + barrier hedge (Nt+Bh), and Nt + subsoiling (Nt+Sb), compared to conventional tillage (Ct) to evaluate their influence on soil water content (SWC) in the profile (10 to 110 cm depth), the soil compaction and their interaction with the crop yield. Experimental plots were established in 2007 and lasted 3 yr till 2009 in a compacted Alfisol. At the end of the growing seasons, SWC was reduced by 44 to 51% in conservation tillage systems and 60% in Ct. Soil water content had a significant (p < 0.05) interaction with tillage system and depth; Nt+Sb showed lower SWC between 10 to 30 cm, but higher and similar to the rest between 50 to 110 cm except for Ct. Although, SWC was higher in conservation tillage systems, the high values on soil compaction affected yield. No tillage + subsoiling reduced soil compaction and had a significant increment of grain yield (similar to Ct in seasons 2008 and 2009). These findings show us that the choice of conservation tillage in compacted soils of the Mediterranean region needs to improve soil structure to obtain higher yields and increment SWC

IMU-Mouse: design and implementation of a pointing device for people with disabilities

La aplicación adecuada de las TIC (Tecnologías de la Información y Comunicación) para el aprendizaje de personas con discapacidad física exige estudios dirigidos a la adaptación de interfaces. El control sobre el diseño e implementación de dispositivos de entrada contribuiría al desarrollo de interfaces capaces de atender las necesidades en el contexto descrito anteriormente. El objetivo de este trabajo es presentar el desarrollo y la validación del dispositivo apuntador IMU-Mouse, para el cual se tiene el control sobre su diseño e implementación dirigido a la investigación de interfaces, que hagan uso de las capacidades de interacción del aparato en los procesos de adaptación. El dispositivo está dirigido a atender las necesidades inducidas por la discapacidad física en extremidades superiores y por esto opera con los movimientos de la cabeza. Las acciones de clic y desplazamiento del IMU-Mouse se ejecutan a partir del procesamiento de los datos generados por un acelerómetro y un giroscopio. Los principales aspectos de la interacción fueron evaluados por un grupo de 13 personas mediante una encuesta basada en el anexo C del estándar ISO 9241-9. De acuerdo con los resultados obtenidos, se concluye que el dispositivo habilita una interacción efectiva con el computador, y además permiten la identificación de espacios para la aplicación de complementos de hardware y software para asistir las acciones de interacción.The correct application of ICTs (information and communications technologies) to the education of people with physical disabilities requires studies aimed to adapt interfaces. Controlling the design and implementation of input devices would contribute to develop interfaces tailored to the requirements of such context. The purpose of this work is to present the development and validation of the IMU-Mouse pointer device whose design and implementation is controlled—for researching interfaces that make the most of the interaction capabilities of the devices in adaptation processes. The purpose of the device is to address the needs created by physical disability in upper limps; hence it operates with head movements. Both actions of the IMU-Mouse, click and move, are performed by processing the data generated by an accelerometer and a gyroscope. The main interaction features of the IMU-Mouse were assessed by group of 13 people by means of a survey based on Annex C of ISO 9241-9 standard. The results lead to conclude that the device enables an effective interaction with the computer, as well as the identification of spaces for the application of hardware and software add-ons to support interaction

Constraints on the braneworld from compact stars

According to the braneworld idea, ordinary matter is confined on a three-dimensional space (brane) that is embedded in a higher-dimensional space-time where gravity propagates. In this work, after reviewing the limits coming from general relativity, finiteness of pressure and causality on the brane, we derive observational constraints on the braneworld parameters from the existence of stable compact stars. The analysis is carried out by solving numerically the brane-modified Tolman–Oppenheimer–Volkoff equations, using different representative equations of state to describe matter in the star interior. The cases of normal dense matter, pure quark matter and hybrid matter are considered.info:eu-repo/semantics/publishedVersio

Efectos de la calidad del agua en la resistencia del concreto

Este es el segundo proyecto de una serie que estudia los "Efectos de la calidad del agua en la resistencia del concreto". En el primer proyecto se analizan los efectos producidos por diferentes concentraciones de sulfatos, sólidos disueltos y materia orgánica en el agua de mezcla, sobre la resistencia y manejabilidad del concreto. En esta segunda parte se estudia únicamente el efecto del sulfato de magnesio en un rango de concentraciones en el agua de mezcla de 600 a 1.200 mg/lt. con variación de 100 mg/lt en las concentraciones, según la recomendación dada en la primera parte

Magnetized Particle Capture Cross Section for Braneworld Black Hole

Capture cross section of magnetized particle (with nonzero magnetic moment) by braneworld black hole in uniform magnetic field is considered. The magnetic moment of particle was chosen as it was done by \citet{rs99} and for the simplicity particle with zero electric charge is chosen. It is shown that the spin of particle as well as the brane parameter are to sustain the stability of particles circularly orbiting around the black hole in braneworld i.e. spin of particles and brane parameter try to prevent the capture by black hole.Comment: 7 pages, 4 figures, Accepted for publication in Astrophysics & Space Scienc

Soil water content effects on net ecosystem CO2 exchange and actual evapotranspiration in a Mediterranean semiarid savanna of Central Chile

Biosphere-atmosphere water and carbon fluxes depend on ecosystem structure, and their magnitudes and seasonal behavior are driven by environmental and biological factors. We studied the seasonal behavior of net ecosystem CO2 exchange (NEE), Gross Primary Productivity (GPP), Ecosystem Respiration (RE), and actual evapotranspiration (ETa) obtained by eddy covariance measurements during two years in a Mediterranean Acacia savanna ecosystem (Acacia caven) in Central Chile. The annual carbon balance was −53 g C m−2 in 2011 and −111 g C m−2 in 2012, showing that the ecosystem acts as a net sink of CO2, notwithstanding water limitations on photosynthesis observed in this particularly dry period. Total annual ETa was of 128 mm in 2011 and 139 mm in 2012. Both NEE and ETa exhibited strong seasonality with peak values recorded in the winter season (July to September), as a result of ecosystem phenology, soil water content and rainfall occurrence. Consequently, the maximum carbon assimilation rate occurred in wintertime. Results show that soil water content is a major driver of GPP and RE, defining their seasonal patterns and the annual carbon assimilation capacity of the ecosystem, and also modulating the effect that solar radiation and air temperature have on NEE components at shorter time scales.This work was funded by FONDECYT projects 1120713 and 1170429, a grant from the Inter-American Institute for Global Change Research (IAI) [grant number CRN3056], which is supported by the US National Science Foundation [grant number GEO-1128040], and the Spanish Ministry of Economy and Competitiveness project GEI Spain (CGL2014-52838-C2-1-R), including ERDF founds. F. Bravo-Martínez is grateful to CONICYT for the grants “Formación de Capital Humano Avanzado-2009′′, “Beca de Apoyo al término de la tesis doctoral-2012′′, and CORFO INNOVA Grant N° 09CN14-5704. We thank to Enrique Pérez Sanchez-Cañete and Borja Ruíz- Reverter for technical support. We also thank “CODELCO–División Andina” for use of the site. C. Montes acknowledges the NASA Postdoctoral Program and to Universities Space Research Association

Leaf-level photosynthetic capacity in lowland Amazonian and high elevation, Andean tropical moist forests of Peru

We examined whether variations in photosynthetic capacity are linked to variations in theenvironment and/or associated leaf traits for tropical moist forests (TMFs) in the Andes/west-ern Amazon regions of Peru. We compared photosynthetic capacity (maximal rate of carboxylation of Rubisco (Vcmax),and the maximum rate of electron transport (Jmax)), leaf mass, nitrogen (N) and phosphorus(P) per unit leaf area (Ma,Naand Pa, respectively), and chlorophyll from 210 species at 18field sites along a 3300-m elevation gradient. Western blots were used to quantify the abun-dance of the CO₂-fixing enzyme Rubisco. Area- and N-based rates of photosynthetic capacity at 25°C were higher in upland than low-land TMFs, underpinned by greater investment of N in photosynthesis in high-elevation trees. Soil [P] and leaf Pa were key explanatory factors for models of area-based Vcmax and Jmax but did not account for variations in photosynthetic N-use efficiency. At any given Na and Pa, the fraction of N allocated to photosynthesis was higher in upland than lowland species. For a smallsubset of lowland TMF trees examined, a substantial fraction of Rubisco was inactive. These results highlight the importance of soil- and leaf-P in defining the photosyntheticcapacity of TMFs, with variations in N allocation and Rubisco activation state further influenc-ing photosynthetic rates and N-use efficiency of these critically important forests

Queer In AI: A Case Study in Community-Led Participatory AI

Queerness and queer people face an uncertain future in the face of ever more widely deployed and invasive artificial intelligence (AI). These technologies have caused numerous harms to queer people, including privacy violations, censoring and downranking queer content, exposing queer people and spaces to harassment by making them hypervisible, deadnaming and outing queer people. More broadly, they have violated core tenets of queerness by classifying and controlling queer identities. In response to this, the queer community in AI has organized Queer in AI, a global, decentralized, volunteer-run grassroots organization that employs intersectional and community-led participatory design to build an inclusive and equitable AI future. In this paper, we present Queer in AI as a case study for community-led participatory design in AI. We examine how participatory design and intersectional tenets started and shaped this community’s programs over the years. We discuss different challenges that emerged in the process, look at ways this organization has fallen short of operationalizing participatory and intersectional principles, and then assess the organization’s impact. Queer in AI provides important lessons and insights for practitioners and theorists of participatory methods broadly through its rejection of hierarchy in favor of decentralization, success at building aid and programs by and for the queer community, and effort to change actors and institutions outside of the queer community. Finally, we theorize how communities like Queer in AI contribute to the participatory design in AI more broadly by fostering cultures of participation in AI, welcoming and empowering marginalized participants, critiquing poor or exploitative participatory practices, and bringing participation to institutions outside of individual research projects. Queer in AI’s work serves as a case study of grassroots activism and participatory methods within AI, demonstrating the potential of community-led participatory methods and intersectional praxis, while also providing challenges, case studies, and nuanced insights to researchers developing and using participatory methods