Focus and social contagion of environmental organization advocacy on Twitter

This is the author accepted manuscript. The final version is freely available from Wiley / Society for Conservation Biology via the DOI in this record.  Agriculture, over-exploitation and urbanisation remain the major threats to biodiversity in the Anthropocene. The attention these threats garner among leading environmental NGOs (eNGOs) and the wider public is critical in fostering the political will necessary to reverse biodiversity declines worldwide. Here, I analyse the advocacy of leading eNGOs on Twitter, and show that it is dominated by the major threats of climate change and over-exploitation, and the minor threat of plastic pollution. The major threats of agriculture, urbanisation, invasions, and pollution are rarely addressed. Content relating to over-exploitation and plastic pollution is more socially contagious than other content. Increasing emotional negativity further increases social contagion, while increasing emotional positivity does not. Scientists, policymakers and eNGOs should consider how narrowly focused advocacy on platforms like Twitter will contribute to effective global biodiversity conservation. Article impact statement: Reversing global biodiversity declines requires focus on major threats, but leading environmental NGOs often focus on minor threats. This article is protected by copyright. All rights reserved.Leverhulme Trus

On the full Kostant-Toda system and the discrete Korteweg-de Vries equations

The relation between the solutions of the full Kostant–Toda lattice and the discrete Korteweg–de Vries equation is analyzed. A method for constructing solutions of these systems is given. As a consequence of the matricial interpretation of this method, the transform of Darboux is extended for general Hessenberg banded matrices

Complex high order Toda and Volterra lattices

Given a solution of a high order Toda lattice we construct a one parameter family of new solutions. In our method, we use a set of B¨acklund transformations in such a way that each new generalized Toda solution is related to a generalized Volterra solution.Dirección General de Investigación, Ministerio de Educación y Ciencia, MTM2006-13000-C03-02; Universidad Politécnica de Madrid; Comunidad Autónoma de Madrid CCG06-UPM/MTM- 539; CMUC/FC

Trophic cascades and the transient keystone concept

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this recordApex predator reintroductions are commonly motivated by the imperative to restore populations and wider ecosystem function by precipitating trophic cascades that release basal species. Yet evidence for the existence of such cascades is often equivocal, particularly where consumptive interactions between apex and intermediate predators are weak or absent. Here, using a tri-trophic skate-crab-bivalve study-system, we find that non-consumptive interactions between apex skate and intermediate crabs cascade down to consumptive interactions between crabs and bivalves, significantly reducing bivalve mortality. However, skate only functioned as keystone where crabs foraged for bivalves in the absence of mature bivalve reef: where reef was present, bivalve mortality was not significantly different in the presence or absence of skate. By facilitating the establishment of basal species which, in turn, diminish apex-intermediate effects, the skate's keystone function is subject to negative regulation. Thus, we propose that keystone functionality can be transient with respect to environmental context. Our findings have two central implications for apex predator reintroductions and basic ecology: (i) species hitherto not considered as keystone may have the capacity to act as such transiently, and; (ii) keystones are known to regulate ecosystems, but transience implies that ecosystems can regulate keystone function.Natural Environment Research Council (NERC

Biomass encounter rates limit the size scaling of feeding interactions

This is the final version. Available from the publisher via the DOI in this record.The rate that consumers encounter resources in space necessarily limits the strength of feeding interactions that shape ecosystems. To explore the link between encounters and feeding, we first compiled the largest available dataset of interactions in the marine benthos by extracting data from published studies and generating new data. These data indicate that the size‐scaling of feeding interactions varies among consumer groups using different strategies (passive or active) to encounter different resource types (mobile or static), with filter feeders exhibiting the weakest feeding interactions. Next, we used these data to develop an agent‐based model of resource biomass encounter rates, underpinned by consumer encounter strategy and resource biomass density. Our model demonstrates that passive strategies for encountering small, dispersed resources limits biomass encounter rates, necessarily limiting the strength of feeding interactions. Our model is based on generalisable assumptions, providing a framework to assess encounter‐based drivers of consumption and coexistence across systems.Leverhulme Trus

Dynamics and interpretation of some integrable systems via multiple orthogonal polynomials

High-order non symmetric difference operators with complex coefficients are considered. The correspondence between dynamics of the coefficients of the operator defined by a Lax pair and its resolvent function is established. The method of investigation is based on the analysis of the moments for the operator. The solution of a discrete dynamical system is studied. We give explicit expressions for the resolvent function and, under some conditions, the representation of the vector of functionals, associated with the solution for the integrable systems

Problemas Actuales de Política Educacional en Chile, indagando en tiempo. Investigación Documental. ¿ Qué refleja el actual sistema de evalucación docente, como politica educativa, de la democracia chilena?

Trabajo presentado en la cátedra Política y Gestión Educacional en Chile, Magíster en política y gestión Educacional.Vivimos en una sociedad que ve a las formas evaluativas como parte de la realidad diaria. Dentro de este ámbito, la Evaluación Docente debería ser una más entre tantas, por lo que no tendría que llamar la atención más de lo que es en sí misma; sin embargo esto no sucede, puesto que no ha quedado lo suficientemente claro el tipo de evaluación que es, su finalidad como fortalecimiento, por una parte, de la profesión docente y por otra, su influencia directa, pero no exclusiva, en la calidad de la educación. No se debe dejar de lado su origen, el cual se gesta en un modelo de Democracia tan singular como lo es el modelo neoliberal de nuestra democracia, que pareciera tener más ribetes de una democracia más bien técnica, que una de carácter participativo. Bajo esta mirada, la Política de la Evaluación Docente se puede definir bajo dos ámbitos evaluativos: el democrático versus el tecno-evaluativo