4,998 research outputs found
Book Review: \u3cem\u3eChrist and Krishna: Where the Jordan Meets the Ganges\u3c/em\u3e
A review of Christ and Krishna: Where the Jordan Meets the Ganges by Steven J. Rosen
Book Review: \u3ci\u3eKášášŁáša and Christ: Body-Divine Relation in the Thought of Ĺaáš kara, RÄmÄnuja, and Classical Christian Orthodoxy\u3c/i\u3e
Book review of KášášŁáša and Christ: Body-Divine Relation in the Thought of Ĺaáš
kara, RÄmÄnuja, and Classical Christian Orthodoxy. By Steven Tsoukalas. Eugene, OR: WIPF & STOCK, 2011, 310 pages
Book Review: \u3ci\u3eCaste, Gender, and Christianity in Colonial India: Telugu Women in Mission\u3c/i\u3e
Book review of Caste, Gender, and Christianity in Colonial India: Telugu Women in Mission. By James Elisha Taneti. New York: Palgrave Macmillan, 2013, 203 pages
Effect of doping on the optical gain and the spontaneous noise enhancement factor in quantum well amplifiers and lasers studied by simple analytical expressions
The maximum optical gain and the spontaneous noise enhancement factor in quantum well structures are expressed as extremely simple functions that are accurate over a wide range of carrier densities. These expressions are used to study the effect of doping on the optical gain and the noise enhancement factor in a 100 Ă
InGaAs/InP quantum well structure. n-type doping is most effective in reducing the transparency excitation level (laser threshold) and the noise enhancement factor (amplifier noise figure), whereas p-type doping enables increased gain at a given excitation level
Analytical technique for determining the polarization dependence of optical matrix elements in quantum wires with band-coupling effects
We present an analytical technique for determining polarization-dependent optical transition matrix elements in quantum wires which rigorously incorporates the effects of band coupling. Using this technique, we examine the polarization anisotropy of the two lowest energy optical transitions in a GaAs quantum wire. Contrary to assumptions employed in previous studies, we show that the valence states involved in these transitions are a strong admixture of light and heavy hole character. The lowest energy transition is found to be four times stronger for electric fields oriented parallel to the wire than for the perpendicular orientation. In contrast, the next highest transition does not interact with optical waves polarized along the wire axis. We discuss sources of error which arise in simpler one-band models of this phenomenon in addition to the neglect of band coupling and show that the coupled band model presented here is essential for predicting these effects
Living with helicopter noise : evaluating sound insulation techniques for domestic dwellings using real helicopters
Specific remedial works designed to improve sound installation and reduce the noise level produced by helicopters inside dwellings are described. The theoretical problems and practical solutions to installing high performance acoustic insulation to a traditional property in the UK are presented. A novel application of ISO 140-5 is presented using real helicopters to measure sound insulation in-situ in the presence of multiple flanking transmission paths. Dedicated field trials to evaluate the performance of such acoustic double-glazing and associated modifications systems were performed and the precautions taken to minimise measurement uncertainties over the extended time period of the trials are detailed. The field trials involved the use of military training helicopters following selected flight paths around the property while noise level measurements were made internally and externally, before and after replacement of the existing single glazed windows and attenuated ventilation units were installed. The results show that after replacing the main windows with acoustic insulated glazing units, insulation levels of 40dB or above are achieved in most rooms. The results also illustrate the importance of effectively addressing ventilation when windows are replaced. It is concluded that despite complications due to sound flanking and regulatory ventilation, the use of acoustic double-glazing units and properly attenuated ventilation units can effectively reduce helicopter noise in suitable dwellings
Chaotic Quivering of Micron-Scaled On-Chip Resonators Excited by Centrifugal Optical Pressure
Opto-mechanical chaotic oscillation of an on-chip resonator is excited by the radiation-pressure nonlinearity. Continuous optical input, with no external feedback or modulation, excites chaotic vibrations in very different geometries of the cavity (both tori and spheres) and shows that opto-mechanical chaotic oscillations are an intrinsic property of optical microcavities. Measured phenomena include period doubling, a spectral continuum, aperiodic oscillations, and complex trajectories. The rate of exponential divergence from a perturbed initial condition (Lyapunov exponent) is calculated. Continuous improvements in cavities mean that such chaotic oscillations can be expected in the future with many other platforms, geometries, and frequency spans
Opto-Mechanical Chaotic Behaviour of Micron-Scaled On-Chip Resonators
Opto-mechanical vibration of an on-chip oscillator is experimentally excited by radiation-pressure nonlinearity to a regime where oscillation is chaotic. Period-doubling and broad power spectra are measured in spherical and toroidal-resonators
- âŚ