Statistical multi-moment bifurcations in random delay coupled swarms

We study the effects of discrete, randomly distributed time delays on the dynamics of a coupled system of self-propelling particles. Bifurcation analysis on a mean field approximation of the system reveals that the system possesses patterns with certain universal characteristics that depend on distinguished moments of the time delay distribution. Specifically, we show both theoretically and numerically that although bifurcations of simple patterns, such as translations, change stability only as a function of the first moment of the time delay distribution, more complex patterns arising from Hopf bifurcations depend on all of the moments

Crackling noise in three-point bending of heterogeneous materials

We study the crackling noise emerging during single crack propagation in a specimen under three-point bending conditions. Computer simulations are carried out in the framework of a discrete element model where the specimen is discretized in terms of convex polygons and cohesive elements are represented by beams. Computer simulations revealed that fracture proceeds in bursts whose size and waiting time distributions have a power law functional form with an exponential cutoff. Controlling the degree of brittleness of the sample by the amount of disorder, we obtain a scaling form for the characteristic quantities of crackling noise of quasi-brittle materials. Analyzing the spatial structure of damage we show that ahead of the crack tip a process zone is formed as a random sequence of broken and intact mesoscopic elements. We characterize the statistics of the shrinking and expanding steps of the process zone and determine the damage profile in the vicinity of the crack tip.Comment: 11 pages, 15 figure

Early Memories of Individuals on the Autism Spectrum Assessed Using Online Self-Reports

"When I was one and a half years old, I was on a ferry lying on red seats" - while several autobiographical accounts by people with autism reveal vivid memories of early childhood, the vast amount of experimental investigations found deficits in personal autobiographic memory in autism. To assess this contradiction empirically, we implemented an online questionnaire on early childhood events to compare people on the autism spectrum (AS) and non-autistic people with respect to their earliest autobiographical episodic memories and the earliest semantic know event as told by another person. Results indicate that people on the AS do not differ from non-autistic people in the age of their earliest know events but remember events from an earlier age in childhood and with more sensory details, contradicting the assumption of an overall deficit in personal episodic memory in autism. Furthermore, our results emphasize the supporting influence of language for memory formation and give evidence for an important role of sensory features in memories of people on the AS.publishe

Predicting electrical conductivity in Cu/Nb composites: a combined model-experiment study

The generation of high magnetic fields requires materials with high electric conductivity and good strength properties. Cu/Nb composites are considered to be good candidates for this purpose. In this work we aim to predict, from theory, the dependence of electric conductivity on the microstructure, most notably on the layer thickness and grain sizes. We also conducted experiments to calibrate and validate our simulations. Bimetal interfaces and grain boundaries are confirmed to have the largest impact on conductivity in this composite material. In this approach, a distribution of the layer thickness is accounted for in order to better model the experimentally observed microstructure. Because layer thicknesses below the mean free path of Cu significantly degrade the conductivity, an average layer thickness larger than expected may be needed to meet conductivity requirements in order to minimize these smaller layers in the distribution. We also investigate the effect of variations in volume fraction of Nb and temperature on the material's conductivity.Comment: 19 pages, 5 figures, 2 table

Fusarium Mycotoxins and Metabolites that Modulate Their Production

The genus Fusarium is a group of fungi producing several types of toxins with toxicological effect in both humans and animals. Such fungi are commonly found in soils so it can contaminate various types of crops, preferably cereals, leading to significant economic losses. Relative humidity, storage temperature and various handling in cereales increase the possibility of contamination by Fusarium toxins. Cereals naturally have secondary metabolites that may help attenuate contamination by these toxins, but it is necessary to know strategies and mechanisms that generate inactivation mycotoxins. This chapter reviews relevant information about cereal mycotoxin contamination, as well as the production of cereal secondary metabolites as a strategy to reduce the possibility of mycotoxin contamination

“Descubiertas” las hembras ovíparas de Xerobion georgii (Mier Durante & Nieto Nafría, 1991) (Hemiptera, Aphididae, Aphidinae, Aphidini)

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Primera cita de Aphis commensalis Stroyan, 1952 (Hemiptera, Aphididae) en España

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El género Impatientinum Mordvilko, 1914 (Hemiptera, Aphididae, Macrosiphini) en América, con la descripción de tres nuevas especies

The study of the specimens of genus Impatientinum Mordvilko, 1914 from the collection générale d’aphides del Muséum national d’Historie naturelle, Paris (France) and the Colección de Aphididae de México at the Universidad Nacional Autónoma de México has allowed to establish 3 species: I. chiriquense n. sp. (with the description of the apterous and alate females) from Panama, I. holmani n. sp. (with the description of the apterous and alate females and males) and I. oaxacense n. sp. (with the description of the apterae) from México. The viviparous alate females of I. americanum are described and knowledge of the apterous females of this species is improved. The generic position of the American species of Impatientinum is discussed. An identification key for the apterous females of the American species of Impatientinum is presented; this key can substitute the key by Blackman and Eastop for the World’s aphids on Cuphea P.Browne (Myrtales, Lythraceae).El estudio de los ejemplares del género Impatientinum Mordvilko, 1914 de la collection générale d’aphides del Muséum national d’Historie naturelle de París (Francia) y de la Colección de Aphididae de México en la Universidad Nacional Autónoma de México ha permitido establecer 3 especies: I. chiriquense n. sp. (con la descripción de hembras ápteras y aladas) de Panamá, I. holmani n. sp. (con la descripción de hembras ápteras, aladas y de machos) e I. oaxacense n. sp. (con la descripción de ápteras) de México. Se describen también las vivíparas aladas y se mejora el conocimiento de las vivíparas ápteras de I. americanum. Se discute la ubicación genérica de las especies del género presentes en América. Se facilita la clave para la identificación de las hembras vivíparas ápteras de las especies americanas del género, que puede sustituir a la clave de Blackman & Eastop para las especies de pulgones que viven sobre plantas del género Cuphea P.Browne (Myrtales, Lythraceae) en el mundo