Quantum electrodynamics of resonance energy transfer in nanowire systems

Nonradiative resonance energy transfer (RET) provides the ability to transfer excitation energy between contiguous nanowires (NWs) with high efficiency under certain conditions. Nevertheless, the well-established Forster formalism commonly used to represent RET was developed for energy transfer primarily between molecular blocks (i.e., from one molecule, or part of a molecule, to another). Although deviations from Forster theory for functional blocks such as NWs have been studied previously, the role of the relative distance, the orientation of transition dipole moment pairs, and the passively interacting matter on electronic energy transfer are to a large extent unknown. Thus, a comprehensive theory that models RET in NWs is required. In this context, analytical insights to give a deeper and more intuitive understanding of the distance and orientation dependence of RET in NWs is presented within the framework of quantum electrodynamics. Additionally, the influence of an included intermediary on the rate of excitation energy transfer is illustrated, embracing indirect energy transfer rate and quantum interference. The results deliver equations that afford new intuitions into the behavior of virtual photons. In particular, results indicate that RET efficiency in a NW system can be explicitly expedited or inhibited by a neighboring mediator, depending on the relative spacing and orientation of NWs

Galaxy destruction and diffuse light in clusters

Deep images of the Centaurus and Coma clusters reveal two spectacular arcs of diffuse light that stretch for over 100 kpc, yet are just a few kpc wide. At a surface brightness of m_b \sim 27-28th arcsec^-2, the Centaurus arc is the most striking example known of structure in the diffuse light component of a rich galaxy cluster. We use numerical simulations to show that the Centaurus feature can be reproduced by the tidal debris of a spiral galaxy that has been tidally disrupted by the gravitational potential of NGC 4709. The surface brightness and narrow dimensions of the diffuse light suggest that the disk was co-rotating with its orbital path past pericentre. Features this prominent in clusters will be relatively rare, although at fainter surface brightness levels the diffuse light will reveal a wealth of structure. Deeper imaging surveys may be able to trace this feature for several times its presently observed extent and somewhere along the tidal debris, a fraction of the original stellar component of the disk will remain bound, but transformed into a faint spheroidal galaxy. It should be possible to confirm the galactic origin of the Centaurus arc by observing planetary nebulae along its length with redshifts close to that of NGC 4709.Comment: Replaced with version accepted by MNRAS (Dec. 1999): Added missing reference (to pg. 4 & reference list). Section 3 shortened; removed three figures. Now 8 pages long, with 8 figures. Low resolution images included, high resolution version available at http://star-www.dur.ac.uk:80/~calcaneo/cenarc.htm

Optical control of resonance energy transfer in quantum dot systems

We demonstrate that the rate of resonance energy transfer can be extensively controlled through an applied off-resonant radiation field under favourable physical configurations of the quantum dots

Going for broke: a multiple case study of brokerage in education

Although the central role of educational intermediaries that can connect research and practice is increasingly appreciated, our present understanding of their motivations, products, and processes is inadequate. In response, this multiple-case study asks how and why three large-scale intermediaries—Edutopia, the Marshall Memo, and Usable Knowledge—are engaging in brokerage activities, and compares the features of the knowledge they seek to share and mobilize. These entities were deliberately chosen and anticipated to reveal diversity. Multiple data sources were analyzed based primarily upon Ward’s knowledge mobilization framework. These entities contrasted widely, especially in relation to core knowledge dimensions, enabling us to identify two distinct brokerage types. To conclude, theoretical (how to conceptualize brokerage) and practical (how to foster interactive knowledge exchange) implications are presented. This study also reveals certain innovative mobilization approaches, including skillful use of social media and the production of videos depicting how and why to adopt particular strategies

Hybrid Modeling for Scenario-Based Evaluation of Failure Effects in Advanced Hardware-Software Designs

This paper describes an incremental scenario-based simulation approach to evaluation of intelligent software for control and management of hardware systems. A hybrid continuous/discrete event simulation of the hardware dynamically interacts with the intelligent software in operations scenarios. Embedded anomalous conditions and failures in simulated hardware can lead to emergent software behavior and identification of missing or faulty software or hardware requirements. An approach is described for extending simulation-based automated incremental failure modes and effects analysis, to support concurrent evaluation of intelligent software and the hardware controlled by the softwar

Effect of head rotation on the apparent frontal plane

This was a study of the effect of prolonged maintenance of a rotated head position on the apparent frontal plane, as determined by using a rotating-plane apparatus, Measurements of the apparent frontal plane were obtained before and after a forty-five minute adaptation period in which the subject\u27s head was restrained in a rotated position, by means of a surgical collar. Stereoscopic information was withheld during this time by covering the dominant eye with a white patch. In both test and re-test conditions the plane of the subject\u27s face was congruent with the frontal plane of his body, Results showed that relative to the before settings the apparent frontal plane was rotated toward the subject on the side toward which his head had been rotated

Radio Continuum Structure of the Orion Nebula

We have imaged the large-scale radio continuum structure in the Orion region with the Very Large Array at 330 MHz. Arcminute-resolution morphology of the extended emission in the H II regions M42 and M43 (NGC 1976 and NGC 1982) and in the NGC 1973-75-77 nebulosity to the north are presented. A low surface brightness thermal radio halo is detected in the H II region M42: comparison with an optical photograph indicates that the radio emission distinguishes optical emission structures from reflection nebulosities. In NGC 1977 we have discovered a compact, steep-spectrum radio source coincident with a bright optical rim