Trapping and Steering on Lattice Strings: Virtual Slow Waves, Directional and Non-propagating Excitations

Using a lattice string model, a number of peculiar excitation situations related to non-propagating excitations and non-radiating sources are demonstrated. External fields can be used to trap excitations locally but also lead to the ability to steer such excitations dynamically as long as the steering is slower than the field's wave propagation. I present explicit constructions of a number of examples, including temporally limited non-propagating excitations, directional excitation and virtually slowed propagation. Using these dynamical lattice constructions I demonstrate that neither persistent temporal oscillation nor static localization are necessary for non-propagating excitations to occur.Comment: 16 pages, 5 figures, RevTex4, references added, figure captions improved, to appear in Physical Review

Topological IIR Filters over Simplicial Topologies via Sheaves

Topology offers a means to formally generalize digital filtering methods based on digital linear translation-invariant (LTI) filters while also, in principle, incorporating translation-variant and nonlinear methods as well as studying large scale (global) properties of filter problems. In this letter we show how the full content of LTI digital filter theory can be incorporated into the formalism of topological filters as introduced by Robinson. In particular, we will give the feedback filter construction associated with infinite impulse responses (IIR). The result allows for direct translation of LTI filters into topological filters, which are sheaves of finite vector spaces and suitably constructed linear maps over simplicial topologies.Comment: 5 pages, 3 figures, accepted for publication: IEEE Signal Processing Letter

Exploiting road traffic data for very short term load forecasting in smart grids

If accurate short term prediction of electricity consumption is available, the Smart Grid infrastructure can rapidly and reliably react to changing conditions. The economic importance of accurate predictions justifies research for more complex forecasting algorithms. This paper proposes road traffic data as a new input dimension that can help improve very short term load forecasting. We explore the dependencies between power demand and road traffic data and evaluate the predictive power of the added dimension compared with other common features, such as historical load and temperature profiles

Hooking up Web Audio to WebGL Typography

Presented at the 2nd Web Audio Conference (WAC), April 4-6, 2016, Atlanta, Georgia.This presentation was presented as part of a poster/demo session on April 5, 2016. Timestamp: 09:41 - 10:31.This demo introduces programmable text rendering that enables temporal typography in web browsers. Textual interaction is seen not only as a dynamic but interactive process facilitating both scripted and live musical expression in various contexts such as audio-visual performance using keyboards and live coding visualization. We transform plain text into a highly audiovisual medium and a musical interface which is visually expressive by transforming textual properties using real-time web audio signal. Technical realization of the concept uses Web Audio API, WebGL and GLSL shaders. We show a number of examples that illustrate instances of the concept in various scenarios ranging from simple textual visualization, live coding environments and interactive writing platform

The effect of cross-boundary management on the trajectory to commonness in biological invasions

The number of alien species introduced and undergoing range expansion in novel environments is steadily increasing, with important consequences for native ecosystems. The efficacy of management planning and decision making to limit such invasions can be improved by understanding how interventions will impact the population dynamics of recently introduced species. To do so, here we expand on a typological framework that enables the classification of populations over time into 10 categories of commonness, and apply it to a spatially discrete metapopulation with heterogeneous abundance across spatial units (patches). We use this framework to assess the effect of cross-boundary management on the capacity of a metapopulation with different demographic and dispersal characteristics, including time lags in population growth, to become common. We demonstrate this framework by simulating a simple theoretical metapopulation model capable of exploring a range of environments, species characteristics, and management actions. Management can vary in the efficacy of propagule interception between patches, and in the synchronisation of the implementation of these measures across patches (i.e. if management is implemented simultaneously across patches). Simulations show that poor interception efficacy that only modestly reduces the number of propagules entering a given spatial unit cannot be compensated for by strong management synchronisation between spatial units. Management synchronisation will nonetheless result in a reduction in rates of spread once a critical threshold of interception efficacy has been met. Finally, time lags in population growth that may result in delayed spread are an important aspect to be considered in management as they can amplify the efficacy of management. Our results demonstrate how a typological framework of categories of commonness can be used to provide practical insights for the management of biological invasions

Empathy: A clue for prosocialty and driver of indirect reciprocity.

Indirect reciprocity has been proposed to explain prosocial behavior among strangers, whereby the prosocial act is returned by a third party. However, what happens if the prosocial act cannot be observed by the third party? Here, we examine whether empathy serves as a clue for prosociality and whether people are more generous toward more empathetic people. In a laboratory study, we measured prosocial behavior as the amount sent in the dictator game and empathy based on the Interpersonal Reactivity Index (IRI). By using an incentivized task, we find that people believe that more empathetic participants send more money in the dictator game. Thus, people see empathy as a clue for prosocial behavior. Furthermore, in a second dictator game, participants indirectly reciprocate by sending more money to more empathetic recipients. Therefore, we suggest that empathy can replace a reputation derived from observable prosocial behavior in triggering indirect reciprocity