Si-based resonant-cavity-enhanced photodetector

We report one top-illumination and one bottom-illumination SiGe/Si multiple quantum-well (MQW) resonant-cavity-enhanced (RCE) photodetector fabricated on a separation-by-implanted-oxygen (SIMOX) wafer operating near 1300 nm. The buried oxygen layer in SIMOX is used as a mirror to form a vertical cavity with the silicon dioxide/silicon Bragg reflector deposited on the top surface. A peak responsivity with a reverse bias of 5 V is measured 10.2 mA/W at 1285 nm, a full width at half maximum of 25 nm for the top-illumination RCE photodetector, 19 mA/W at 1305 nm, and a full width at half maximum of 14 nm for the bottom-illumination one. The external quantum efficiency of the bottom-illumination RCE photodetector is up to 2.9% at 1305 nm, with a reverse bias of 25V. The responsivity of the bottom-illumination RCE photodetector is improved by two-fold compared with that of the top-illumination one. (C) 2001 Society of Photo-Optical Instrumentation Engineers.

Si-based resonant-cavity-enhanced photodetector

Resonant-cavity-enhanced (RCE) photodetectors have been demonstrated to be able to improve the bandwidth-efficiency product. We report one top-illumination and one bottom-illumination SiGe/Si multiple quantum-well (MQW) RCE photodetectors fabricated on a separation-by-implanted-oxygen (SIMOX) wafer operating near 1300nm, The buried oxide layer in SIMOX is used as a mirror to form a vertical cavity with the silicon dioxide/silicon Bragg reflector deposited on the top surface. A peak responsivity with a reverse bias of 5V is measured 10.2mA/W at 1285nm, and a full-width at half maximum of 25nm for the top-illumination RCE photodetector, and 19mA/W at 1305nm, and a full-width at half maximum of 14nm for the bottom-illumination one. The external quantum efficiency of the bottom-illumination RCE photodetector is up to 2.9% at 1305nm with a reverse bias of 25V. The responsivity of the bottom-illumination RCE photodetector is improved by two-fold compared with that of the top-illumination one.

From the account manager’s conscience to top-of-mind : account planning in Australia

What began as the “account manager’s conscience” has grown to be top-of-mind in Australian advertising today. Account planning is a hybrid discipline which uses research to bring the consumer voice to the campaign process during strategy generation, creative development and evaluation. In Australia, account planning is subjected to the “Vegemite Factor” where planners are spread too thinly across accounts and much of the market is dominated by freelance researchers and planners. This unique environment has shaped many different perceptions of account planning in Australia. These are compared with an international definition of account planning and the current research. While many basic tenants of the definition are shared by Australian advertising professionals, the difference appears to be in the ongoing nature, team approach and level of commitment. In Australia, account planners seem to be more facilitators of the strategic direction, than directors of it. Instead of exerting a sustained influence across the campaign, most energy appears to be expended at the start of campaign development, rather than extending through to its evaluation.

Optimisation of performance in top level athletes : an action-based coping approach : a commentary

INTRODUCTION In their target article, Yuri Hanin and Muza Hanina outlined a novel multidisciplinary approach to performance optimisation for sport psychologists called the Identification-Control-Correction (ICC) programme. According to the authors, this empirically-verified, psycho-pedagogical strategy is designed to improve the quality of coaching and consistency of performance in highly skilled athletes and involves a number of steps including: (i) identifying and increasing self-awareness of ‘optimal’ and ‘non-optimal’ movement patterns for individual athletes; (ii) learning to deliberately control the process of task execution; and iii), correcting habitual and random errors and managing radical changes of movement patterns. Although no specific examples were provided, the ICC programme has apparently been successful in enhancing the performance of Olympic-level athletes. In this commentary, we address what we consider to be some important issues arising from the target article. We specifically focus attention on the contentious topic of optimization in neurobiological movement systems, the role of constraints in shaping emergent movement patterns and the functional role of movement variability in producing stable performance outcomes. In our view, the target article and, indeed, the proposed ICC programme, would benefit from a dynamical systems theoretical backdrop rather than the cognitive scientific approach that appears to be advocated. Although Hanin and Hanina made reference to, and attempted to integrate, constructs typically associated with dynamical systems theoretical accounts of motor control and learning (e.g., Bernstein’s problem, movement variability, etc.), these ideas required more detailed elaboration, which we provide in this commentary.

Strategic short termism as an issue of top-teams’ temporal orientation

Short-termism among firms, the tendency to excessively discount long-term benefits and favour less valuable short-term benefits, has been a prominent issue in business and public policy debates but research to date has been inconclusive. We study how managers frame, interpret, and resolve problems of intertemporal choice in actual decisions by using computer aided text analysis to measure the frequency of top-team temporal references in 1653 listed Australian firms between 1992-2005. Contrary to short-termism arguments we find evidence of a significant general increase in Future orientation and a significant decrease in Current/Past orientation. We also show top-teams’ temporal orientation is related to their strategic orientation, specifically the extent to which they focus on Innovation-Expansion and Capacity Building.

Aberrations and pupil location under corneal topography and Hartmann-Shack illumination conditions

PURPOSE. This study was conducted to determine the magnitude of pupil center shift between the illumination conditions provided by corneal topography measurement (photopic illuminance) and by Hartmann-Shack aberrometry (mesopic illuminance) and to investigate the importance of this shift when calculating corneal aberrations and for the success of wavefront-guided surgical procedures. METHODS. Sixty-two subjects with emmetropia underwent corneal topography and Hartmann-Shack aberrometry. Corneal limbus and pupil edges were detected, and the differences between their respective centers were determined for both procedures. Corneal aberrations were calculated using the pupil centers for corneal topography and for Hartmann-Shack aberrometry. Bland-Altmann plots and paired t-tests were used to analyze the differences between corneal aberrations referenced to the two pupil centers. RESULTS. The mean magnitude (modulus) of the displacement of the pupil with the change of the illumination conditions was 0.21 ± 0.11 mm. The effect of this pupillary shift was manifest for coma corneal aberrations for 5-mm pupils, but the two sets of aberrations calculated with the two pupil positions were not significantly different. Sixty-eight percent of the population had differences in coma smaller than 0.05 µm, and only 4% had differences larger than 0.1 µm. Pupil displacement was not large enough to significantly affect other higher-order Zernike modes. CONCLUSIONS. Estimated corneal aberrations changed slightly between photopic and mesopic illumination conditions given by corneal topography and Hartmann-Shack aberrometry. However, this systematic pupil shift, according to the published tolerances ranges, is enough to deteriorate the optical quality below the theoretically predicted diffraction limit of wavefront-guided corneal surgery.

A biomechanical study of top screw pullout in anterior scoliosis correction constructs

Study Design: Biomechanical testing of vertebral body screw pullout resistance with relevance to top screw pullout in endoscopic anterior scoliosis constructs. Objectives: To analyse the effect of screw positioning and angulation on pullout resistance of vertebral body screws, where the pullout takes place along a curved path as occurs in anterior scoliosis constructs. Summary of Background Data: Top screw pullout is a significant clinical problem in endoscopic anterior scoliosis surgery, with rates of up to 18% reported in the literature. Methods: A custom designed biomechanical test rig was used to perform pullout tests of Medtronic anterior vertebral screws where the pullout occurred along an arc of known radius. Using synthetic bone blocks, a range of pullout radii and screw angulations were tested, in order to determine an ‘optimal’ configuration. The optimal configuration was then compared with standard screw positioning using a series of tests on ovine vertebrae (n=29). Results: Screw angulation has a small but significant effect on pullout resistance, with maximum strength being achieved at 10 degree cephalad angulation. Combining 10 degree cephalad angulation with maximal spacing between the top two screws (maximum pullout radius) increased the pullout resistance by 88% compared to ‘standard’ screw positioning (screws inserted perpendicular to rod at mid-body height). Conclusions: The positioning of the top screw in anterior scoliosis constructs can significantly alter its pullout resistance.

Top Gear, top journalism : three lessons for political journalists from the world's most popular TV show

This article examines the BBC program Top Gear, discussing why it has become one of the world’s most-watched TV programs, and how it has very successfully captivated an audience who might otherwise not be particularly interested in cars. The analysis of the show is here framed in the form of three ‘lessons’ for journalists, suggesting that some of the entertaining (and highly engaging) ways in which Top Gear presents information to its viewers could be usefully applied in the coverage of politics – a domain of knowledge which, like cars, many citizens find abstract or boring.