Estimation of the Optimal Nitrogen Dose in a \u3ci\u3eBrachiaria humidicola\u3c/i\u3e-Corn Rotation System in the Colombian Eastern Plains

Improving nitrogen (N) use efficiency by optimizing the N fertilizer application dose is one way to reduce greenhouse gas (GHG) emissions in agriculture and livestock production, especially in higher demanding crops such as corn. Taking a Brachiaria humidicola (Bh)-corn rotation system in the Colombian Eastern Plains, we seek to determine both the optimal economic dose (OED) and the optimal technical dose (OTD) of N, which allow to maximize income at producer level and minimize environmental impacts. This particular rotation system was chosen as research subject given the presence of the residual effect of Biological Nitrogen Inhibition (BNI) in permanent lots of Bh, which has positive impacts on corn production such as increased yields and better N efficiency. The data for this study was obtained from trials conducted between 2013 and 2017, where corn production in a Bh-corn rotation system (with residual BNI effect) was compared with conventional corn production (without residual BNI effect). For determining the OED and OTD of N, three response models were applied: a pseudo-quadratic model (PQM), a quadratic model (QM) and a discontinuous-rectilinear model (DRM). The results show that the PQM and DRM models turn out to be the most suitable for estimating the OTD producing a better fit for the data, thus the required N doses are not overestimated. Bh-corn treatments require lower OTD and OED compared to the control scenario, which results from the residual BNI effect. The OED is lower than the OTD in the QM and PQM models for the three treatments. Thus, for maximizing profits a lower N dose is required. Both N input and corn sales price variables determine the optimum dose for maximizing the producer\u27s profits. In general, estimating the correct doses of N in a Bh-corn rotation system contributes to improving both efficiency in production and profitability, helping to avoid excessive application of N fertilizers and its associated negative effects on the environment

What and Who Has Determined Adoption? A Study on Improved Forage Technologies in Colombia from an Agricultural Innovation System (AIS) Perspective

The complex process behind the adoption of improved forages in Colombia remains largely unexplored. Despite governmental and scientific efforts to promote and disseminate the implementation of improved forages for the sake of sustainable livestock production, local livestock producers continue to extensively use native species and adoption rates of more efficient forages remain low. This study explores the dynamics behind the development and diffusion of improved forage technologies in Colombia, from the 1960\u27s to the present through an Agricultural Innovation Systems (AIS) perspective. Here we map the agents involved, classify the roles they exerted over time and reconstruct the historical context in which the creation and dissemination of forage technologies in the country took form. Through the use of qualitative research tools such as in-depth interviews, and extensive archival work, we were able to identify various factors determining the course of improved forage adoption processes. First, a gradual decline on public and private investment destined to agricultural research hindered national scientific agendas and affected the continuity of ongoing projects. Second, the primacy of interpersonal relationships further complicates this panorama as it can either interfere with or promote the use of improved forages, subjecting technology dissemination to a non-institutional realm. Thirdly, released technological packages remain incomplete and impede rising adoption rates, mainly due to both Colombia’s low-latitude (and its restrictions for national seed production) and ineffective processes of training and support aimed at local livestock producers. Aside from the identification of key actors and historical trends, the study concludes by suggesting the implementation of a systematic (AIS) approach that gives account of the complex and ever-changing process of forage adoption, its agents, roles, strengths and limitations so that a comprehensive diagnosis can serve as a guideline for future adoption policies in the subject

From Theory to Practice: What Should We Have in Mind When Building Effective and Sustainable Payments for Ecosystem Services (PES) Schemes for Silvo-Pastoral Systems? Evidence from Colombia

In most Latin American countries, payment for ecosystem services (PES) can be a useful strategy for restoration and conservation of the environment, increasing productivity and promoting sustainable development in rural areas. Despite these plausible benefits, PES implementation can be challenging due to the contextual framework in which it takes place (e.g. institutional weakness in the implementation and monitoring stages, limited connectivity among stakeholders, low adoption levels of agricultural technology). This study aims at evaluating PES schemes for silvo-pastoral systems in Colombia by considering six dimensions based on an extensive literature review: policy and governance; social context; environmental context; risks and challenges; dynamics; and monitoring and evaluation approaches. A literature meta-analysis and semi-structured interviews with decision makers were carried out. The results suggest that: 1) It is necessary to restructure PES schemes given their limited scope in developing countries; 2) A new approach towards successful PES schemes should be adopted, transitioning from temporary conservation-oriented PES to schemes focused on the articulation of value chains and thus, transmitting costs to the final consumers; 3) Although policies regarding PES have been increasing, governance systems and responsibility assignments remain unclear; and 4) PES are more likely to be efficient when accompanied by complementary strategies (e.g. technical assistance, mechanisms for market inclusion) and conservation strategies that last in time. This study revealed the difficulties in monitoring territories as well as the underlying dynamics of implementing PES schemes in farms with nettle aptitude to receive them (despite the willingness of the producers). It also highlights the importance of analyzing the cultural and economic dimensions of the producers to assess the assigned importance of nature conservation. This work enriches the debate and informs the dialogue among PES experiences in order to guide public and private strategies in developing countries

Exchange operator formalism for N-body spin models with near-neighbors interactions

We present a detailed analysis of the spin models with near-neighbors interactions constructed in our previous paper [Phys. Lett. B 605 (2005) 214] by a suitable generalization of the exchange operator formalism. We provide a complete description of a certain flag of finite-dimensional spaces of spin functions preserved by the Hamiltonian of each model. By explicitly diagonalizing the Hamiltonian in the latter spaces, we compute several infinite families of eigenfunctions of the above models in closed form in terms of generalized Laguerre and Jacobi polynomials.Comment: RevTeX, 31 pages, no figures; important additional conten

Estrategia pedag?gica para disminuir la deserci?n escolar

68 p. Recurso Electr?nicoEste proyecto de investigaci?n hace parte del proceso de formaci?n de la Especializaci?n en Gerencia de Instituciones Educativas del IDEAD, Universidad del Tolima, cuyo prop?sito fundamental es contribuir a la disminuci?n de los ?ndices de deserci?n escolar de la Instituci?n Educativa T?cnica Musical Amina Melendro de Pulecio, Sede San Jorge, de la ciudad de Ibagu?; mediante la formulaci?n de una estrategia pedag?gica. Luego de avanzar en el proceso de investigaci?n diagn?stica sobre la problem?tica observada por docentes y funcionarios especialmente en el Grado Quinto de la secci?n primaria de la instituci?n educativa y la aplicaci?n de algunas herramientas como entrevistas semi-estructuradas y estructuradas, encuestas, observaci?n y revisi?n directa de documentos institucionales y de emprender una revisi?n bibliogr?fica en busca de la fundamentaci?n y comprensi?n de la problem?tica observada, se pudo determinar que la principal causa de deserci?n escolar en esta Instituci?n es la p?rdida paulatina del inter?s musical por parte de los estudiantes. Mediante el desarrollo de un ejercicio de an?lisis reflexivo de los resultados obtenidos y el planteamiento de diferentes opciones, finalmente se opt? por el dise?o y formulaci?n del proyecto de aula trasversal ?Aprendiendo al son de la m?sica? como estrategia pedag?gica, que involucra a los docentes de las ?reas b?sicas y que pretende incentivar continuamente el gusto por la m?sica en los estudiantes, para que as? permanezcan y contin?en su proceso de formaci?n acad?mica y musical. Palabras Claves: Deserci?n escolar, estrategia pedag?gica.This research project makes part of the process of formation of the specialization in management of educational institutions of the IDEAD, Tolima University, whose fundamental purpose is to contribute to decrease the index of school desertion of the Educational Technical Musical Institution Amina Melendro in Puelcio, San Jorge headquarters, in the city of Ibagu?; Through the formulation of a pedagogical strategy. After advancing in the diagnostic research process about the problem observed by the teachers and functionaries, especially in grade 5th of the elementary section in the educational institution and the application of some tools, such as semi-structured interviews, surveys, observation and direct revision of institutional documents and of undertaking a bibliographic review searching for the foundation and comprehension of the problem observed, it could be determined that the main cause of school desertion in this institution is the gradual loss of the musical interest on behalf of the students. Though the development of an exercise of reflexive analysis of the results obtained and the careful study of different options, it was finally decided the design and formulation of the cross classroom project named ?learning to the sound of music? as a pedagogical strategy that involves teachers from the basic areas and that pretends to encourage continuously the students? taste for music, so in this way they may remain in the school and continue their academic and musical formation. Keywords: School desertion, pedagogical strategy, cross classroom project

Habitat fragmentation influences nestling growth in Mediterranean blue and great tits

In patchy forest areas, the size of the forest patch where birds breed has a strong influence on their breeding success. However, the proximate effects contributing to lowering the breeding success in small forest patches remain unclear; and a shortage of crucial resources in those forest patches has been suggested to account in some degree for this failure. With the aim to further investigate this issue, we have monitored the breeding cycle of blue and great tits in three ‘large’ forest patches (ranging between 26.5-29.6 ha) and twelve ‘small’ forest patches (ranging between 1.1-2.1 ha) in a Mediterranean area in central Spain, during three years (2011-2013). We also recorded the nestling diet inside the nest-boxes with the aid of handy-cams. Only males significantly differed between forest patch size categories; being on average younger and with better body condition in small patches for great and blue tits respectively. Reproductive traits did not vary between forest patch size categories, but the body condition of blue tit nestlings and the size of great tit nestlings did, being significantly better and larger respectively in large forest patches. The recruitment rate of blue tit nestlings was also higher in large patches. Regarding nestling diet, blue tits did not differ but great tits did, delivering a larger amount of caterpillars in large forest patches. Most variation in the reproductive traits occurred between years, probably due to annual differences in environmental conditions. This study suggests that food supply could be limiting the breeding success of birds above all in small patches, but also in large patches under particular environmental conditions.Funding was provided by Ministerio de Ciencia e Innovación (CGL2010-21933-C02-01) and Junta de Comunidades de Castilla-La Mancha and European Social Fund (POIC10-0269-7632). ESF and JBE are both supported by a doctoral scholarship from Junta de Comunidades de Castilla-La Mancha-European Social Fund. RB benefited from the JCCM-FSE 2007/2013 postdoctoral program and from a “Juan de la Cierva” post-doctoral contract (JCI-2011-10945) and ESD enjoyed a pre-doctoral fellowship from Ministerio de Ciencia e Innovación.Peer reviewe

La resolución de problemas y sus interrelaciones con el contexto cultural : determinación de referenciales para la formulación de una propuesta de formación inicial de licenciados en Química

Esta comunicación presenta un análisis de documentos sobre investigaciones que sustentan, tanto el modelo de resolución de problemas (RP), como sobre el contexto cultural y la enseñanza de las ciencias. Lo anterior, con el fin de configurar preguntas que orienten el estudio de las prácticas de profesores universitarios de futuros profesores de Química. El análisis arrojo cuatro campos de estudio que se concretan en cuatro preguntas. Por ello, esta investigación orienta la indagación en torno a los interrogantes que se producen, a partir de la integración del contexto cultural a la perspectiva de RP en el marco de la formación inicial de Licenciados en Química. Esta integración genera nuevas perspectivas que podrían ser fundamentadas epistemológicamente

La resolución de problemas y sus interrelaciones con el contexto cultural : determinación de referenciales para la formulación de una propuesta de formación inicial de licenciados en Química

Esta comunicación presenta un análisis de documentos sobre investigaciones que sustentan, tanto el modelo de resolución de problemas (RP), como sobre el contexto cultural y la enseñanza de las ciencias. Lo anterior, con el fin de configurar preguntas que orienten el estudio de las prácticas de profesores universitarios de futuros profesores de Química. El análisis arrojo cuatro campos de estudio que se concretan en cuatro preguntas. Por ello, esta investigación orienta la indagación en torno a los interrogantes que se producen, a partir de la integración del contexto cultural a la perspectiva de RP en el marco de la formación inicial de Licenciados en Química. Esta integración genera nuevas perspectivas que podrían ser fundamentadas epistemológicamente

Qxpak.5: Old mixed model solutions for new genomics problems

Mixed models have a long and fruitful history in statistics. They are pertinent to genomics problems because they are highly versatile, accommodating a wide variety of situations within the same theoretical and algorithmic framework. Qxpak is a package for versatile statistical genomics, specifically designed for sophisticated quantitative trait loci and association analyses. Multiple loci, multiple trait, infinitesimal genetic effects, imprinting, epistasis or sex linked loci can be fitted. The new version (v. 5) allows us, among other new features, to include either relationship matrices obtained with molecular information or user defined matrices that can be read from an input file. This feature can be used for genome selection or - more importantly - to correct for population structure in association studies. In crosses, two parental lines, not necessarily inbred, can be accommodated. This software aims at simplifying statistical genetic analyses implementing a coherent and unified approach by mixed models. It provides a tool that can be used in a wide variety of situations with ample genetic and statistical modeling flexibility. The software, a complete manual and examples are available at http://www.icrea.cat/Web/OtherSectionViewer.aspx?key=485&titol=Software:Qxpak.