Electron and Ion Acceleration in Relativistic Shocks with Applications to GRB Afterglows

We have modeled the simultaneous first-order Fermi shock acceleration of protons, electrons, and helium nuclei by relativistic shocks. By parameterizing the particle diffusion, our steady-state Monte Carlo simulation allows us to follow particles from particle injection at nonthermal thermal energies to above PeV energies, including the nonlinear smoothing of the shock structure due to cosmic-ray (CR) backpressure. We observe the mass-to-charge (A/Z) enhancement effect believed to occur in efficient Fermi acceleration in non-relativistic shocks and we parameterize the transfer of ion energy to electrons seen in particle-in-cell (PIC) simulations. For a given set of environmental and model parameters, the Monte Carlo simulation determines the absolute normalization of the particle distributions and the resulting synchrotron, inverse-Compton, and pion-decay emission in a largely self-consistent manner. The simulation is flexible and can be readily used with a wide range of parameters typical of gamma-ray burst (GRB) afterglows. We describe some preliminary results for photon emission from shocks of different Lorentz factors and outline how the Monte Carlo simulation can be generalized and coupled to hydrodynamic simulations of GRB blast waves. We assume Bohm diffusion for simplicity but emphasize that the nonlinear effects we describe stem mainly from an extended shock precursor where higher energy particles diffuse further upstream. Quantitative differences will occur with different diffusion models, particularly for the maximum CR energy and photon emission, but these nonlinear effects should be qualitatively similar as long as the scattering mean free path is an increasing function of momentum.Comment: Accepted for publication in MNRA

Intending to be ethical: An examination of consumer choice in sweatshop avoidance

While much research in ethical consumption has focused on contexts such as food, this research explores ethical consumer decision-making in the context of intention to avoid sweatshop apparel. This research seeks to deepen the Theory of Planned Behavior with respect to the motivation and volitional stages underlying behavior. The findings of the research, based on 794 consumers, are novel and support an enriched framework which reveals that the role of attitude, subjective norm and perceived behavioral control are mediated by desire, intention and plan. The findings have implications for research seeking to address the ‘intention-behavior’ gap

The orchestra of ideas: Using music to enhance the ‘fuzzy front end’ phase of product innovation

By introducing music composition theory, we offer a new perspective from which to understand the ‘fuzzy front end’ (FFE) phase of product innovation with regard to both value outcomes and the innovation process. Focusing on ideas co-created by consumers, we draw on an ethnographic study to examine how young consumers tackled a real-life challenge to produce a digital product that would engage audiences in classical music. Working with two organizations, one a city symphony orchestra, the other a global technology corporation, this work bridges innovation and aesthetics and challenges the established mind-set of the science-art schism in business management. The findings contribute to innovation theory by introducing a hybrid model that structures FFE activities based around the composing process. We also illuminate how music can facilitate and ensure greater value for consumers as ‘the composers of ideas’. Managerial implications are suggested

An Examination of the Volitional Stages in Consumer Decisions to Avoid Sweatshop Clothing

While much research in ethical consumption has focused on contexts such as food, this research explores ethical consumer decision-making in the context of intention to avoid sweatshop clothing where consumer concern has increased but response from the market remains limited. This research seeks to deepen the theory of planned behaviour with respect to the volitional stages underlying behaviour. The findings of the research support a modified theory of planned behaviour model and also reveal volitional stages from intention to trying and plan which reveal the stages of consumer decision-making to avoid sweatshop clothing. Implications for consumer decision-making are discussed

A CR-hydro-NEI Model of Multi-wavelength Emission from the Vela Jr. Supernova Remnant (SNR RX J0852.0-4622)

Based largely on energy budget considerations and the observed cosmic-ray (CR) ionic composition, supernova remnant (SNR) blast waves are the most likely sources of CR ions with energies at least up to the "knee" near 3 PeV. Shocks in young shell-type TeV-bright SNRs are surely producing TeV particles, but the emission could be dominated by ions producing neutral pion-decay emission or electrons producing inverse-Compton gamma-rays. Unambiguously identifying the GeV-TeV emission process in a particular SNR will not only help pin down the origin of CRs, it will add significantly to our understanding of the diffusive shock acceleration (DSA) mechanism and improve our understanding of supernovae and the impact SNRs have on the circumstellar medium. In this study, we investigate the Vela Jr. SNR, an example of TeV-bright non-thermal SNRs. We perform hydrodynamic simulations coupled with non-linear DSA and non-equilibrium ionization near the forward shock (FS) to confront currently available multi-wavelength data. We find, with an analysis similar to that used earlier for SNR RX J1713.7-3946, that self-consistently modeling the thermal X-ray line emission with the non-thermal continuum in our one-dimensional model strongly constrains the fitting parameters, and this leads convincingly to a leptonic origin for the GeV-TeV emission for Vela Jr. This conclusion is further supported by applying additional constraints from observation, including the radial brightness profiles of the SNR shell in TeV gamma-rays, and the spatial variation of the X-ray synchrotron spectral index. We will discuss implications of our models on future observations by the next-generation telescopes.Comment: 12 pages, 10 figures, to appear at the Astrophysical Journa

3D Location of Circular and Spherical Features by Monocular Model-Based Vision

This paper addresses the mathematics for using monocular model-based vision to find the 3-D positions of circular and spherical model features, and, for the circular case, orientations as well. Monocular model-based vision here refers to the use of a single projective image of modeled objects to solve for the 3-D positions and orientations of the objects in the scene. The mathematics for solving 3-dimensional position and orientation of the object from matched model and image points/lines features are well known. However, no known paper addresses spherical features arid very few papers address the mathematics involving circular model features. This paper describes a novel closed-formed solution for the 3-D position and orientation of a circular features and the 3-D position of a spherical feature. The number of solutions for the circular case is found to be two in general, but there is only one solution when the surface normal of the circular feature passes through the center of projection. There is only one solution for the circular case. Advantages of this method are: (1) Handles spherical as well as circular features. (2) Closed-form solution. (3) Gives only the necessary number of solutions (no redundant solutions). (4) Simple mathematics involving 3-D analytic Geometry. (5) Geometrically intuitive

The Impact of Progenitor Mass Loss on the Dynamical and Spectral Evolution of Supernova Remnants

There is now substantial evidence that the progenitors of some core-collapse supernovae undergo enhanced or extreme mass loss prior to explosion. The imprint of this mass loss is observed in the spectra and dynamics of the expanding blastwave on timescales of days to years after core-collapse, and the effects on the spectral and dynamical evolution may linger long after the supernova has evolved into the remnant stage. In this paper, we present for the first time, largely self-consistent end-to-end simulations for the evolution of a massive star from the pre-main sequence, up to and through core collapse, and into the remnant phase. We present three models and compare and contrast how the progenitor mass loss history impacts the dynamics and spectral evolution of the supernovae and supernova remnants. We study a model which only includes steady mass loss, a model with enhanced mass loss over a period of $\sim$ 5000 years prior to core-collapse, and a model with extreme mass loss over a period of $\sim$ 500 years prior to core collapse. The models are not meant to address any particular supernova or supernova remnant, but rather to highlight the important role that the progenitor evolution plays in the observable qualities of supernovae and supernova remnants. Through comparisons of these three different progenitor evolution scenarios, we find that the mass loss in late stages (during and after core carbon burning) can have a profound impact on the dynamics and spectral evolution of the supernova remnant centuries after core-collapse.Comment: 18 pages, 11 figures; submitted to the Astrophysical Journa

Case-based reasoning: concepts, features and soft computing

Here we first describe the concepts, components and features of CBR. The feasibility and merits of using CBR for problem solving is then explained. This is followed by a description of the relevance of soft computing tools to CBR. In particular, some of the tasks in the four REs, namely Retrieve, Reuse, Revise and Retain, of the CBR cycle that have relevance as prospective candidates for soft computing applications are explained