Cohort aggregation modelling for complex forest stands: Spruce-aspen mixtures in British Columbia

Mixed-species growth models are needed as a synthesis of ecological knowledge and for guiding forest management. Individual-tree models have been commonly used, but the difficulties of reliably scaling from the individual to the stand level are often underestimated. Emergent properties and statistical issues limit their effectiveness. A more holistic modelling of aggregates at the whole stand level is a potentially attractive alternative. This work explores methodology for developing biologically consistent dynamic mixture models where the state is described by aggregate stand-level variables for species or age/size cohorts. The methods are demonstrated and tested with a two-cohort model for spruce-aspen mixtures named SAM. The models combine single-species submodels and submodels for resource partitioning among the cohorts. The partitioning allows for differences in competitive strength among species and size classes, and for complementarity effects. Height growth reduction in suppressed cohorts is also modelled. SAM fits well the available data, and exhibits behaviors consistent with current ecological knowledge. The general framework can be applied to any number of cohorts, and should be useful as a basis for modelling other mixed-species or uneven-aged stands.Comment: Accepted manuscript, to appear in Ecological Modellin

Higgs bundles and higher Teichm\"uller spaces

This paper is a survey on the role of Higgs bundle theory in the study of higher Teichm\"uller spaces. Recall that the Teichm\"uller space of a compact surface can be identified with a certain connected component of the moduli space of representations of the fundamental group of the surface into $\mathrm{PSL}(2,{\mathbb{R}})$. Higher Teichm\"uller spaces correspond to special components of the moduli space of representations when one replaces $\mathrm{PSL}(2,{\mathbb{R}})$ by a real non-compact semisimple Lie group of higher rank. Examples of these spaces are provided by the Hitchin components for split real groups, and maximal Toledo invariant components for groups of Hermitian type. More recently, the existence of such components has been proved for $\mathrm{SO}(p,q)$, in agreement with the conjecture of Guichard and Wienhard relating the existence of higher Teichm\"uller spaces to a certain notion of positivity on a Lie group that they have introduced. We review these three different situations, and end up explaining briefly the conjectural general picture from the point of view of Higgs bundle theory.Comment: arXiv admin note: substantial text overlap with arXiv:1511.0775

The y-genus of the moduli space of PGL_n-Higgs bundles on a curve (for degree coprime to n)

Building on our previous joint work with A. Schmitt [7] we explain a recursive algorithm to determine the cohomology of moduli spaces of Higgs bundles on any given curve (in the coprime situation). As an application of the method we compute the y-genus of the space of PGL_n-Higgs bundles for any rank n, confirming a conjecture of T. Hausel.Comment: 13 page

Anti-holomorphic involutions of the moduli spaces of Higgs bundles

We study anti-holomorphic involutions of the moduli space of principal $G$-Higgs bundles over a compact Riemann surface $X$, where $G$ is a complex semisimple Lie group. These involutions are defined by fixing anti-holomorphic involutions on both $X$ and $G$. We analyze the fixed point locus in the moduli space and their relation with representations of the orbifold fundamental group of $X$ equipped with the anti-holomorphic involution. We also study the relation with branes. This generalizes work by Biswas--Garc\'{\i}a-Prada--Hurtubise and Baraglia--Schaposnik.Comment: Final version; to appear in Journal de l'\'Ecole polytechnique--Math\'ematique

Connectedness of Higgs bundle moduli for complex reductive Lie groups

We carry an intrinsic approach to the study of the connectedness of the moduli space $\mathcal{M}_G$ of $G$-Higgs bundles, over a compact Riemann surface, when $G$ is a complex reductive (not necessarily connected) Lie group. We prove that the number of connected components of $\mathcal{M}_G$ is indexed by the corresponding topological invariants. In particular, this gives an alternative proof of the counting by J. Li of the number of connected components of the moduli space of flat $G$-connections in the case in which $G$ is connected and semisimple.Comment: Due to some mistake the authors did not appear in the previous version. Fixed this. Final version; to appear in the Asian Journal of Mathematics. 19 page

Higgs bundles for the non-compact dual of the unitary group

Using Morse-theoretic techniques, we show that the moduli space of U*(2n)-Higgs bundles over a compact Riemann surface is connected.Comment: 20 pages; v2: several improvements and corrections; main results are unchange

EVALUACIÓN DE SUSTRATOS EN LA PRODUCCIÓN DE GERBERA (Gerbera jamesonii Bolus) VAR. BARON

El Estado de México es el principal productor de gerbera (Gerbera jamesonii B.), con una superficie cultivada de 88 hectáreas y una producción de 912,300 toneladas. Dicha especie fue introducida la región de Tenancingo como un cultivo para diversificar el mercado de la flor de corte dominado por la rosa (Rosa x hibrida.), crisantemo (Chrysanthemum morifolium Ramat), clavel (Dianthus caryophyllus L.) y gladiola (Gladiolus spp.). Actualmente su producción se hace en contenedores como bolsas de plástico, comúnmente con mezcla de suelo y tepojal que permitan reducir el número de riegos y facilitan el manejo del cultivo. Sin embargo, a la fecha no se tiene una mezcla que optimice la producción, por lo cual en la presente investigación se planteó comparar cinco mezclas comerciales de sustratos de los productos Agrolita® con el sustrato utilizado por floricultores, en la producción de la variedad de gerbera Barón bajo un diseño completamente al azar con seis tratamientos y cuarenta repeticiones. Los tratamientos fueron: Mezcla 1: T1 (Turba: 60% + Perlita: 20% + Vermiculita: 20 + 6.0 kg/m3 de Multicote 18-06-12+2MgO+ME), Mezcla 2: T2 (Turba: 50% + Perlita: 20% + Vermiculita: 20% + Humus: 10%), Mezcla 3: T3 (Perlita: 20% + Vermiculita: 20% + Fibra de Coco: 60%), Mezcla 4: T4(Fibra de Coco: 50% + Perlita: 20% + Vermiculita: 20% + Humus: 10%), Mezcla 5: T5(Fibra de Coco: 60% + Perlita: 40%) y Testigo: (T6) (Cascarilla de Arroz: 30% + Suelo: 40% + Tepojal. Se registraron lecturas dos veces por semana durante 6 meses. Las variables vegetativas evaluadas fueron: número de hojas por planta NHP, largo de hoja LH, ancho de hoja AH, largo de peciolo LP y las variables de producción floral y calidad: número de botones por planta NB, largo del tallo floral LTF, grosor del tallo floral GT y diámetro del capítulo floral DC. A estos datos se les practicó el Análisis de Varianza y la prueba de Tukey (P=0.05). De acuerdo a los resultados obtenidos los tratamientos 2 y 4 fueron los mejores para las dos etapas evaluadas de crecimiento vegetativo y reproducción-floración respectivamente. En la etapa vegetativa fue más apropiado el Tratamiento 2 y en la etapa de producción de capítulos sobresalió el Tratamiento 4. El cálculo de los costos de los sustratos realizados para 1000 m2 de invernadero, comparando el mejor tratamiento para variables de producción (T4) fue 52.32% más caro que el utilizado por los productores de gerbera. Esta diferencia en costos es recuperada en un mes de producción, considerando exclusivamente la calidad del producto obtenido en el Tratamiento 4 con respecto al Testigo

Building ontologies from folksonomies and linked data: Data structures and Algorithms

We present the data structures and algorithms used in the approach for building domain ontologies from folksonomies and linked data. In this approach we extracts domain terms from folksonomies and enrich them with semantic information from the Linked Open Data cloud. As a result, we obtain a domain ontology that combines the emergent knowledge of social tagging systems with formal knowledge from Ontologies