Spectral preorder and perturbations of discrete weighted graphs

In this article, we introduce a geometric and a spectral preorder relation on the class of weighted graphs with a magnetic potential. The first preorder is expressed through the existence of a graph homomorphism respecting the magnetic potential and fulfilling certain inequalities for the weights. The second preorder refers to the spectrum of the associated Laplacian of the magnetic weighted graph. These relations give a quantitative control of the effect of elementary and composite perturbations of the graph (deleting edges, contracting vertices, etc.) on the spectrum of the corresponding Laplacians, generalising interlacing of eigenvalues. We give several applications of the preorders: we show how to classify graphs according to these preorders and we prove the stability of certain eigenvalues in graphs with a maximal d-clique. Moreover, we show the monotonicity of the eigenvalues when passing to spanning subgraphs and the monotonicity of magnetic Cheeger constants with respect to the geometric preorder. Finally, we prove a refined procedure to detect spectral gaps in the spectrum of an infinite covering graph.Comment: 26 pages; 8 figure

Nonlinear electrodynamics as a symmetric hyperbolic system

Nonlinear theories generalizing Maxwell's electromagnetism and arising from a Lagrangian formalism have dispersion relations in which propagation planes factor into null planes corresponding to two effective metrics which depend on the point-wise values of the electromagnetic field. These effective Lorentzian metrics share the null (generically two) directions of the electromagnetic field. We show that, the theory is symmetric hyperbolic if and only if the cones these metrics give rise to have a non-empty intersection. Namely that there exist families of symmetrizers in the sense of Geroch which are positive definite for all covectors in the interior of the cones intersection. Thus, for these theories, the initial value problem is well-posed. We illustrate the power of this approach with several nonlinear models of physical interest such as Born-Infeld, Gauss-Bonnet and Euler-Heisenberg

Design and Development in Capitalism Peripheries. Methodological Transferences Between HfG-Ulm and INTEC Design Group

El presente texto presenta las inquietudes iniciales de una investigación (CNCA Fondart 2015), que tiene como objetivo el documentar, analizar y difundir la producción del Grupo de Diseño Industrial, liderado por Gui Bonsiepe, y alojado en el Comité de Investigaciones Tecnológicas (INTEC) de corto, entre enero de 1970 y septiembre de 1973, durante la presidencia marxista de Salvador Allende. La investigación busca profundizar en las condiciones de desarrollo disciplinar del diseño industrial en América Latina y en Chile, a través del análisis de los fenómenos de transferencia, adaptación, apropiación y transformación de la metodología disciplinar desarrollada en HfG-Ulm. La hipótesis de trabajo sostiene que a través del análisis de los documentos, y de la reconstrucción analítica de los prototipos generados por el Grupo de Diseño, se podrá reconocer, comprobar y avanzar en el análisis de sus metodologías proyectuales, entendidas como producto de las condiciones culturales y políticas del período, asociadas al rol del diseño en sociedades no competitivas, y a la búsqueda proyectual de una independencia tecnológica.This paper constitutes the starting point of a research (CNCA Fondart 2015) oriented towards the documentation, analysis and dissemination of the production of the Industrial Design Group, a governmental team lead by Gui Bonsiepe, active within the Technological Research Committee (INTEC) of the Chilean Economic Development Agency (CORFO), between January 1970 and September 1973, during the Marxist presidency of Salvador Allende. The research aims to deepen the study of design’s history in Latin America and Chile, by analysing processes of transference, adaptation, appropriation and transformation of design methods coined in post-war Europe, and specifically by HfG-Ulm. The working hypothesis states that the compiling of the Design Group’s archive and the analytical reconstruction of its prototypes would allow determining the late development of these project methodologies, in a cultural and political context defined by a non-competitive society and the national search for technological independence

Inference of Many-Taxon Phylogenies

Phylogenetic trees are tree topologies that represent the evolutionary history of a set of organisms. In this thesis, we address computational challenges related to the analysis of large-scale datasets with Maximum Likelihood based phylogenetic inference. We have approached this using different strategies: reduction of memory requirements, reduction of running time, and reduction of man-hours

Diplomado de Profundización CISCO, Prueba de Habilidades Prácticas CCNP

Mediante el presente documento se realizan algunas tareas asignadas en la prueba de habilidades para los escenarios 1 y 2, documentando la configuración de cada uno de los dispositivos utilizados en cada etapa de los escenarios, se realiza un proceso de verificación de conectividad mediante el uso de comandos en cada dispositivo. En el documento se podrán ver algunas imágenes que muestran el correcto direccionamiento entre los equipos y dispositivos de cada escenario y la verificación de conectividad LAN de cada prueba. Se presenta además el paso a paso del proceso de estructuración de las redes conmutadas utilizadas mediante la utilización de protocolos STP y la configuración de redes VLAN usadas en una infraestructura de red jerárquica convergente.Through this document, some tasks assigned in the skills test for scenarios 1 and 2 are carried out, documenting the configuration of each of the devices used in each stage of the scenarios, a connectivity verification process is carried out through the use of commands on each device. In the document you will be able to see some images that show the correct addressing between the equipment and devices of each scenario and the LAN connectivity verification of each test. The process of structuring the switched networks used through the use of STP protocols and the configuration of VLANs used in a convergent hierarchical network infrastructure is also presented step by step

Midnight Reflections about our own Northern Ventriloquist\u27s Skills

“Midnight Reflections about our own Northern Ventriloquist\u27s Skills” is articulated in the form of a podcast in a conversational style scripted by longtime collaborators composer and performer. It starts by cartographing the authors’ previous collaborative works until they approach their last project ensemble, Campo Amniótico [CA] (2021), work in which the feedback or Larsen plays a paramount role, making the artwork highly unstable and elusive. As a result, performers and composer are in constant trouble, stripped of their cognitive performativity by the once enhancer technology, that in CA becomes almost a threat. That’s when the podcast starts to interact with recorded extracts of philosophers Rosi Braidotti and Achille Mbembe, and psychologist Thirusha Naidu on issues concerning posthumanism, postcolonialism and technological escalation. By applying and discussing their theories in the field of artistic research and, more specifically, in that of contemporary music, the authors will situate CA as a post-human artwork that aims to tip the balance more towards subversion than the status quo. That is following Eve Sedwick\u27s precept, when she said twenty years ago with some disillusionment that the result of a work is usually always the same: a little subversive, a little hegemonic