586 research outputs found
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
Primera cita de <i>Aphis commensalis</i> Stroyan, 1952 (Hemiptera, Aphididae) en España
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“Descubiertas” las hembras ovĂparas de Xerobion georgii (Mier Durante & Nieto NafrĂa, 1991) (Hemiptera, Aphididae, Aphidinae, Aphidini)
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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
Primera cita de Aphis commensalis Stroyan, 1952 (Hemiptera, Aphididae) en España
Not availableNo disponibl
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