Crowd synchrony and quorum sensing in delay-coupled lasers

Crowd synchrony and quorum sensing arise when a large number of dynamical elements communicate with each other via a common information pool. Previous evidence in different fields, including chemistry, biology and civil engineering, has shown that this type of coupling leads to synchronization, when coupling is instantaneous and the number of coupled elements is large enough. Here we consider a situation in which the transmission of information between the system components and the coupling pool is not instantaneous. To that end, we model a system of semiconductor lasers optically coupled to a central laser with a delay. Our results show that, even though the lasers are non-identical due to their distinct optical frequencies, zero-lag synchronization arises. By changing a system parameter, we can switch between two different types of synchronization transition. The dependence of the transition with respect to the delay-coupling parameters is studied.Comment: 4 pages, 4 figure

Graphs without a partition into two proportionally dense subgraphs

A proportionally dense subgraph (PDS) is an induced subgraph of a graph such that each vertex in the PDS is adjacent to proportionally as many vertices in the subgraph as in the rest of the graph. In this paper, we study a partition of a graph into two proportionally dense subgraphs, namely a 2-PDS partition, with and without additional constraint of connectivity of the subgraphs. We present two infinite classes of graphs: one with graphs without a 2-PDS partition, and another with graphs that only admit a disconnected 2-PDS partition. These results answer some questions proposed by Bazgan et al. (2018)

Treewidth versus clique number. II. Tree-independence number

In 2020, we initiated a systematic study of graph classes in which the treewidth can only be large due to the presence of a large clique, which we call $(\mathrm{tw},\omega)$-bounded. While $(\mathrm{tw},\omega)$-bounded graph classes are known to enjoy some good algorithmic properties related to clique and coloring problems, it is an interesting open problem whether $(\mathrm{tw},\omega)$-boundedness also has useful algorithmic implications for problems related to independent sets. We provide a partial answer to this question by means of a new min-max graph invariant related to tree decompositions. We define the independence number of a tree decomposition $\mathcal{T}$ of a graph as the maximum independence number over all subgraphs of $G$ induced by some bag of $\mathcal{T}$. The tree-independence number of a graph $G$ is then defined as the minimum independence number over all tree decompositions of $G$. Generalizing a result on chordal graphs due to Cameron and Hell from 2006, we show that if a graph is given together with a tree decomposition with bounded independence number, then the Maximum Weight Independent Packing problem can be solved in polynomial time. Applications of our general algorithmic result to specific graph classes will be given in the third paper of the series [Dallard, Milani\v{c}, and \v{S}torgel, Treewidth versus clique number. III. Tree-independence number of graphs with a forbidden structure].Comment: 33 pages; abstract has been shortened due to arXiv requirements. A previous version of this arXiv post has been reorganized into two parts; this is the first of the two parts (the second one is arXiv:2206.15092

Aspectos de la respuesta inmune innata en las infecciones intramamarias causadas por Staphylococcus aureus en bovinos

ResumenStaphylococcus aureus es el principal agente causante de mastitis bovina en Argentina y en el mundo. Esta bacteria ocasiona infecciones crónicas que generan importantes pérdidas a los productores y la industria lechera. El objetivo de este artículo es caracterizar los mecanismos que intervienen en la infección causada por S. aureus en la glándula mamaria bovina, evaluando dos aspectos diferentes del proceso infeccioso: por un lado, lo vinculado con la respuesta inmune innata por parte del hospedador, y por otro, la capacidad de la bacteria para evadir el sistema inmune e interactuar con diferentes tipos celulares. La exploración de la interacción de S. aureus con el sistema inmune de la glándula mamaria bovina permitirá identificar blancos para delinear nuevas alternativas preventivas o curativas, que contribuyan a evitar o eliminar las infecciones causadas por este organismo.AbstractStaphylococcus aureus is the pathogen most frequently isolated from bovine mastitis worldwide, causing chronic intramammary infections that limit profitable dairying. The objective of this article is to characterize the mechanisms involved in S. aureus mammary gland infections considering two different aspects of the infectious process; on the one hand, the aspects involved in the host innate immune response and on the other hand, the capacity of this organism to evade the immune system and interact with different cell types. The exploration of S. aureus interactions with the immune response of bovine mammary gland will help identify targets to outline new preventive or curative alternatives for intramammary infections caused by this organism

Aspects of the innate immune response to intramammary Staphylococcus aureus infections in cattle

Staphylococcus aureus es el principal agente causante de mastitis bovina en Argentina y en el mundo. Esta bacteria ocasiona infecciones crónicas que generan importantes pérdidas a los productores y la industria lechera. El objetivo de este artículo es caracterizar los mecanismos que intervienen en la infección causada por S. aureus en la glándula mamaria bovina, evaluando dos aspectos diferentes del proceso infeccioso: por un lado, lo vinculado con la respuesta inmune innata por parte del hospedador, y por otro, la capacidad de la bacteria para evadir el sistema inmune e interactuar con diferentes tipos celulares. La exploración de la interacción de S. aureus con el sistema inmune de la glándula mamaria bovina permitirá identificar blancos para delinear nuevas alternativas preventivas o curativas, que contribuyan a evitar o eliminar las infecciones causadas por este organismo.Staphylococcus aureus is the pathogen most frequently isolated from bovine mastitis worldwide, causing chronic intramammary infections that limit proÀ table dairying. The objective of this article is to characterize the mechanisms involved in S. aureus mammary gland infections considering two different aspects of the infectious process; on the one hand, the aspects involved in the host innate immune response and on the other hand, the capacity of this organism to evade the immune system and interact with different cell types. The exploration of S. aureus interactions with the immune response of bovine mammary gland will help identify targets to outline new preventive or curative alternatives for intramammary infections caused by this organism.Fil: Pereyra, Elizabet Amanda Lorena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Ciencias Veterinarias del Litoral. Universidad Nacional del Litoral. Facultad de Cs.veterinarias. Instituto de Ciencias Veterinarias del Litoral; ArgentinaFil: Dallard, Bibiana Elisabet. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Ciencias Veterinarias del Litoral. Universidad Nacional del Litoral. Facultad de Cs.veterinarias. Instituto de Ciencias Veterinarias del Litoral; ArgentinaFil: Calvinho, Luis Fernando. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe. Estación Experimental Agropecuaria Rafaela; Argentina. Universidad Nacional del Litoral. Facultad de Ciencias Veterinarias; Argentin

Graphs with at most two moplexes

A moplex is a natural graph structure that arises when lifting Dirac's classical theorem from chordal graphs to general graphs. However, while every non-complete graph has at least two moplexes, little is known about structural properties of graphs with a bounded number of moplexes. The study of these graphs is motivated by the parallel between moplexes in general graphs and simplicial modules in chordal graphs: Unlike in the moplex setting, properties of chordal graphs with a bounded number of simplicial modules are well understood. For instance, chordal graphs having at most two simplicial modules are interval. In this work we initiate an investigation of $k$-moplex graphs, which are defined as graphs containing at most $k$ moplexes. Of particular interest is the smallest nontrivial case $k=2$, which forms a counterpart to the class of interval graphs. As our main structural result, we show that the class of connected $2$-moplex graphs is sandwiched between the classes of proper interval graphs and cocomparability graphs; moreover, both inclusions are tight for hereditary classes. From a complexity theoretic viewpoint, this leads to the natural question of whether the presence of at most two moplexes guarantees a sufficient amount of structure to efficiently solve problems that are known to be intractable on cocomparability graphs, but not on proper interval graphs. We develop new reductions that answer this question negatively for two prominent problems fitting this profile, namely Graph Isomorphism and Max-Cut. On the other hand, we prove that every connected $2$-moplex graph contains a Hamiltonian path, generalising the same property of connected proper interval graphs. Furthermore, for graphs with a higher number of moplexes, we lift the previously known result that graphs without asteroidal triples have at most two moplexes to the more general setting of larger asteroidal sets

Functionality of box intersection graphs

Functionality is a graph complexity measure that extends a variety of parameters, such as vertex degree, degeneracy, clique-width, or twin-width. In the present paper, we show that functionality is bounded for box intersection graphs in $\mathbb{R}^1$, i.e. for interval graphs, and unbounded for box intersection graphs in $\mathbb{R}^3$. We also study a parameter known as symmetric difference, which is intermediate between twin-width and functionality, and show that this parameter is unbounded both for interval graphs and for unit box intersection graphs in $\mathbb{R}^2$.Comment: 11 page

Conditions for minimally tough graphs

Katona, Solt\'esz, and Varga showed that no induced subgraph can be excluded from the class of minimally tough graphs. In this paper, we consider the opposite question, namely which induced subgraphs, if any, must necessarily be present in each minimally $t$-tough graph. Katona and Varga showed that for any rational number $t \in (1/2,1]$, every minimally $t$-tough graph contains a hole. We complement this result by showing that for any rational number $t>1$, every minimally $t$-tough graph must contain either a hole or an induced subgraph isomorphic to the $k$-sun for some integer $k \ge 3$. We also show that for any rational number $t > 1/2$, every minimally $t$-tough graph must contain either an induced $4$-cycle, an induced $5$-cycle, or two independent edges as an induced subgraph