Time-dependent angularly averaged inverse transport

This paper concerns the reconstruction of the absorption and scattering parameters in a time-dependent linear transport equation from knowledge of angularly averaged measurements performed at the boundary of a domain of interest. We show that the absorption coefficient and the spatial component of the scattering coefficient are uniquely determined by such measurements. We obtain stability results on the reconstruction of the absorption and scattering parameters with respect to the measured albedo operator. The stability results are obtained by a precise decomposition of the measurements into components with different singular behavior in the time domain

Inverse Transport Theory of Photoacoustics

We consider the reconstruction of optical parameters in a domain of interest from photoacoustic data. Photoacoustic tomography (PAT) radiates high frequency electromagnetic waves into the domain and measures acoustic signals emitted by the resulting thermal expansion. Acoustic signals are then used to construct the deposited thermal energy map. The latter depends on the constitutive optical parameters in a nontrivial manner. In this paper, we develop and use an inverse transport theory with internal measurements to extract information on the optical coefficients from knowledge of the deposited thermal energy map. We consider the multi-measurement setting in which many electromagnetic radiation patterns are used to probe the domain of interest. By developing an expansion of the measurement operator into singular components, we show that the spatial variations of the intrinsic attenuation and the scattering coefficients may be reconstructed. We also reconstruct coefficients describing anisotropic scattering of photons, such as the anisotropy coefficient $g(x)$ in a Henyey-Greenstein phase function model. Finally, we derive stability estimates for the reconstructions

A Game Engine based Networked Infrastructure to Create and Share 3D Abstract Art

Online communities have been proactive in producing collaborative creative content such as music, games and other social interactions. Online collaboration has enabled contributors to peer produce and share masses of creative content. Examples range from information sharing such as Wikipedia to open source software and other specific art projects. Software vendors have recently introduced low cost 2D and 3D content authoring tools allowing user communities to generate and share creative content. Emerging networking programming interfaces available inside modern game engines allow contributors to implement multiplayer or multiuser interaction relatively easily. This paper presents a 3D art creation framework to be used over networked infrastructure in a multiuser environment. Contributors will be able to create 3D sculptures at runtime, share with other users in a common networked working environment and critique each other’s work. Experimental work also involved evaluating procedurally generated meshes versus instantiation of primitive mesh objects. Saving and loading mesh information in an optimum way is also explored

The older the better?: age-related differences in emotion regulation after psychological contract breach

Purpose: The aim of this paper was to investigate the role of emotion regulation and age in reactions to psychological contract breach towards positive and negative affect. We expected that in the context of contract breach, reappraisal emotion regulation mitigate the negative relation with affect. Moreover, based on lifespan theory, suppression emotion regulation was expected to be important for younger workers, because older workers have learned how to express themselves appropriately at the workplace. Consequently, suppression would mitigate the relations of contract breach with well-being only among younger workers, while it strengthened the relation for older workers. Design: Data were collected among 163 employees working in various Dutch organizations. Moderated regression analyses were used to test the hypotheses. Findings: Reappraisal mitigated the relation of contract breach with positive affect, and suppression mitigated the relations of contract breach with positive affect only among younger workers, while for older workers with high suppression the relations were accentuated. We also found that contract breach was more strongly related to negative affect for younger workers than for older workers. Research Implications: Reactions towards psychological contract breaches are influenced by the emotion regulation strategies people employ. Especially reappraisal is important to maintain optimal levels of affect, while suppression is detrimental especially for older workers. Originality/value: This paper is the first study in which emotion regulation strategies are investigated in the context of psychological contract breaches. The paper presents novel insights into how reactions to contract breaches are modified through emotion regulation strategies and age

Fluxon Dynamics of a Long Josephson Junction with Two-gap Superconductors

We investigate the phase dynamics of a long Josephson junction (LJJ) with two-gap superconductors. In this junction, two channels for tunneling between the adjacent superconductor (S) layers as well as one interband channel within each S layer are available for a Cooper pair. Due to the interplay between the conventional and interband Josephson effects, the LJJ can exhibit unusual phase dynamics. Accounting for excitation of a stable 2$\pi$-phase texture arising from the interband Josephson effect, we find that the critical current between the S layers may become both spatially and temporally modulated. The spatial critical current modulation behaves as either a potential well or barrier, depending on the symmetry of superconducting order parameter, and modifies the Josephson vortex trajectories. We find that these changes in phase dynamics result in emission of electromagnetic waves as the Josephson vortex passes through the region of the 2$\pi$-phase texture. We discuss the effects of this radiation emission on the current-voltage characteristics of the junction.Comment: 14 pages, 6 figure

The Cop Number of the One-Cop-Moves Game on Planar Graphs

Cops and robbers is a vertex-pursuit game played on graphs. In the classical cops-and-robbers game, a set of cops and a robber occupy the vertices of the graph and move alternately along the graph's edges with perfect information about each other's positions. If a cop eventually occupies the same vertex as the robber, then the cops win; the robber wins if she can indefinitely evade capture. Aigner and Frommer established that in every connected planar graph, three cops are sufficient to capture a single robber. In this paper, we consider a recently studied variant of the cops-and-robbers game, alternately called the one-active-cop game, one-cop-moves game or the lazy-cops-and-robbers game, where at most one cop can move during any round. We show that Aigner and Frommer's result does not generalise to this game variant by constructing a connected planar graph on which a robber can indefinitely evade three cops in the one-cop-moves game. This answers a question recently raised by Sullivan, Townsend and Werzanski.Comment: 32 page