Laser Guide Stars for Extremely Large Telescopes: Efficient Shack-Hartmann Wavefront Sensor Design using Weighted center-of-gravity algorithm

Over the last few years increasing consideration has been given to the study of Laser Guide Stars (LGS) for the measurement of the disturbance introduced by the atmosphere in optical and near-infrared astronomical observations from the ground. A possible method for the generation of a LGS is the excitation of the Sodium layer in the upper atmosphere at approximately 90 km of altitude. Since the Sodium layer is approximately 10 km thick, the artificial reference source looks elongated, especially when observed from the edge of a large aperture. The spot elongation strongly limits the performance of the most common wavefront sensors. The centroiding accuracy in a Shack-Hartmann wavefront sensor, for instance, decreases proportionally to the elongation (in a photon noise dominated regime). To compensate for this effect a straightforward solution is to increase the laser power, i.e. to increase the number of detected photons per subaperture. The scope of the work presented in this paper is twofold: an analysis of the performance of the Weighted Center of Gravity algorithm for centroiding with elongated spots and the determination of the required number of photons to achieve a certain average wavefront error over the telescope aperture.Comment: 10 pages, 14 figure

Is it dangerous? The role of an emotional visual search strategy and threat‐relevant training in the detection of guns and knives

Counter‐terrorism strategies rely on the assumption that it is possible to increase threat detection by providing explicit verbal instructions to orient people's attention to dangerous objects and hostile behaviours in their environment. Nevertheless, whether verbal cues can be used to enhance threat detection performance under laboratory conditions is currently unclear. In Experiment 1, student participants were required to detect a picture of a dangerous or neutral object embedded within a visual search display on the basis of an emotional strategy ‘is it dangerous?’ or a semantic strategy ‘is it an object?’. The results showed a threat superiority effect that was enhanced by the emotional visual search strategy. In Experiment 2, whilst trainee police officers displayed a greater threat superiority effect than student controls, both groups benefitted from performing the task under the emotional than semantic visual search strategy. Manipulating situational threat levels (high vs. low) in the experimental instructions had no effect on visual search performance. The current findings provide new support for the language‐as‐context hypothesis. They are also consistent with a dual‐processing account of threat detection involving a verbally mediated route in working memory and the deployment of a visual template developed as a function of training

An Adaptive Framework for Selecting Environmental Monitoring Protocols to Support Ocean Renewable Energy Development

Offshore renewable energy developments (OREDs) are projected to become common in the United States over the next two decades. There are both a need and an opportunity to guide efforts to identify and track impacts to the marine ecosystem resulting from these installations. A monitoring framework and standardized protocols that can be applied to multiple types of ORED would streamline scientific study, management, and permitting at these sites. We propose an adaptive and reactive framework based on indicators of the likely changes to the marine ecosystem due to ORED. We developed decision trees to identify suites of impacts at two scales (demonstration and commercial) depending on energy (wind, tidal, and wave), structure (e.g., turbine), and foundation type (e.g., monopile). Impacts were categorized by ecosystem component (benthic habitat and resources, fish and fisheries, avian species, marine mammals, and sea turtles) and monitoring objectives were developed for each. We present a case study at a commercial-scale wind farm and develop a monitoring plan for this development that addresses both local and national environmental concerns. In addition, framework has provided a starting point for identifying global research needs and objectives for understanding of the potential effects of ORED on the marine environment

Impact of age norms and stereotypes on managers' hiring decisions of retirees

Purpose -Our study investigates the role of managers in the re-employment of early retirees and asks what the effect is of managers’ age norms and stereotypes on managers’ employment decisions. Design/methodology/approach- A combination of a factorial study and a survey was conducted. First, information on the age norms and stereotypes was collected. Secondly, profiles of hypothetical retired job applicants were presented to the employers, who were asked to make a specific hiring decision. The information collected during both studies was combined in the analysis and multilevel models were estimated. Findings -The results indicate that higher age norms result in a higher propensity to hire an early retiree. Stereotypes, by contrast, do not influence managers’ decisions. Early retirees’ chances for re-employment are also related to their own circumstances (physical appearance and relevant experience) and organisational forces, as they are hired when organisations face labour force shortages. Research limitation / implications – with the use of vignettes study we deal with hypothetical hiring situation. Originality value- Although the effect of age norms and age stereotypes has been often suggested, not much empirical evidence was presented to support this notion. Our study estimates the effect of age norms and stereotypes on hiring decision. key words: bridge employment; early retirees; age norms; age stereotypes; multilevel models.

Modern optical astronomy: technology and impact of interferometry

The present `state of the art' and the path to future progress in high spatial resolution imaging interferometry is reviewed. The review begins with a treatment of the fundamentals of stellar optical interferometry, the origin, properties, optical effects of turbulence in the Earth's atmosphere, the passive methods that are applied on a single telescope to overcome atmospheric image degradation such as speckle interferometry, and various other techniques. These topics include differential speckle interferometry, speckle spectroscopy and polarimetry, phase diversity, wavefront shearing interferometry, phase-closure methods, dark speckle imaging, as well as the limitations imposed by the detectors on the performance of speckle imaging. A brief account is given of the technological innovation of adaptive-optics (AO) to compensate such atmospheric effects on the image in real time. A major advancement involves the transition from single-aperture to the dilute-aperture interferometry using multiple telescopes. Therefore, the review deals with recent developments involving ground-based, and space-based optical arrays. Emphasis is placed on the problems specific to delay-lines, beam recombination, polarization, dispersion, fringe-tracking, bootstrapping, coherencing and cophasing, and recovery of the visibility functions. The role of AO in enhancing visibilities is also discussed. The applications of interferometry, such as imaging, astrometry, and nulling are described. The mathematical intricacies of the various `post-detection' image-processing techniques are examined critically. The review concludes with a discussion of the astrophysical importance and the perspectives of interferometry.Comment: 65 pages LaTeX file including 23 figures. Reviews of Modern Physics, 2002, to appear in April issu

Increasing survival after admission to UK critical care units following cardiopulmonary resuscitation

© 2016 The Author(s). Background: In recent years there have been many developments in post-resuscitation care. We have investigated trends in patient characteristics and outcome following admission to UK critical care units following cardiopulmonary resuscitation (CPR) for the period 2004-2014. Our hypothesis is that there has been a reduction in risk-adjusted mortality during this period. Methods: We undertook a prospectively defined, retrospective analysis of the Intensive Care National Audit & Research Centre (ICNARC) Case Mix Programme Database (CMPD) for the period 1 January 2004 to 31 December 2014. Admissions, mechanically ventilated in the first 24 hours in the critical care unit and admitted following CPR, defined as the delivery of chest compressions in the 24 hours before admission, were identified. Case mix, withdrawal, outcome and activity were described annually for all admissions identified as post-cardiac arrest admissions, and separately for out-of-hospital cardiac arrest and in-hospital cardiac arrest. To assess whether in-hospital mortality had improved over time, hierarchical multivariate logistic regression models were constructed, with in-hospital mortality as the dependent variable, year of admission as the main exposure variable and intensive care unit (ICU) as a random effect. All analyses were repeated using only the data from those ICUs contributing data throughout the study period. Results: During the period 2004-2014 survivors of cardiac arrest accounted for an increasing proportion of mechanically ventilated admissions to ICUs in the ICNARC CMPD (9.0 % in 2004 increasing to 12.2 % in 2014). Risk-adjusted hospital mortality following admission to ICU after cardiac arrest has decreased significantly during this period (OR 0.96 per year). Over this time, the ICU length of stay and time to treatment withdrawal has increased significantly. Re-analysis including only those 116 ICUs contributing data throughout the study period confirmed all the results of the primary analysis. Conclusions: Risk-adjusted hospital mortality following admission to ICU after cardiac arrest has decreased significantly during the period 2004-2014. Over the same period the ICU length of stay and time to treatment withdrawal has increased significantly

Starfire Optical Range 3.5-m telescope adaptive optical system

A 941 channel, 1500 Hertz frame rate adaptive optical (AO) system has been installed and tested in the coude path of the 3.5m telescope at the USAF Research Laboratory Starfire Optical Range. This paper describes the design and measured performance of the principal components comprising this system and present sample results from the first closed-loop test of the system on stars and an artificial source simulator

Employers’ Perception on the Antecedents of Graduate Employability for the Information Technology Sector

This chapter aims to analyze the perceptions of the employers in the Information Technology (IT) sector in India on the antecedents of graduate employability. With an increased emphasis on Organizational flexibility in today’s volatile and complex Business environment, the employability of the workforce has gained crucial significance. Flexibility has been acknowledged as a predictor of Organizational performance (Sushil, Global J Flex Syst Manag 16(4):309–311, 2015) and its Strategic driver (Sharma et al., Global J Flex Syst Manag 11(3):51–68, 2010). Flexible strategies and business plan often demand the need to scale up the quality of manpower or shift the required skill set to swiftly adapt to the Market changes accordingly. This Flexibility is not confined to the quantity of manpower only but also encompasses the quality of skills deployed by the manpower (Srivastava, Global J Flex Syst Manag 17(1):105–108, 2016). Therefore, it is imperative for the potential Job seeker to understand and continuously adapt to the changing knowledge and skill requirements of the employers to develop and maintain their employability. The employers in this dynamic sector demand a range of knowledge, skills, and other attributes from potential job seekers. However, the graduates passing out of Higher Education Institutions fail to meet these expectations of the employers. Therefore, the sector is struggling with the challenges of talent crunch and qualitative demand–Demand–supply mismatch of manpower. The identification of factors that influence graduate employability is based on literature review. This chapter is empirical and examines the perceptions of the employers on the factors that impact employability and validates the association between the research constructs. Opinion surveys are used to elicit responses from a sample of 236 respondents, i.e., Technical/HR personnel at the middle-level/upper middle-level management positions spanning across 71 reputed IT companies in India. These respondents are actively involved in the staffing of graduates seeking Technical jobs in IT sector. The perception of these employers has been investigated using bivariate and multivariate analysis techniques. The key insights drawn in this chapter enable potential job seekers to clearly understand the employer demands in the IT sector and equip themselves with the required knowledge and skills. This also contributes to enhancing the manpower Flexibility in organizations. The chapter has significant implications for the policy-makers and key stakeholders to bridge the Employability gap in this sector

Predictive value of neurological examination for early cortical responses to somatosensory evoked potentials in patients with postanoxic coma

Bilateral absence of cortical N20 responses of median nerve somatosensory evoked potentials (SEP) predicts poor neurological outcome in postanoxic coma after cardiopulmonary resuscitation (CPR). Although SEP is easy to perform and available in most hospitals, it is worthwhile to know how neurological signs are associated with SEP results. The aim of this study was to investigate whether specific clinical neurological signs are associated with either an absent or a present median nerve SEP in patients after CPR. Data from the previously published multicenter prospective cohort study PROPAC (prognosis in postanoxic coma, 2000–2003) were used. Neurological examination, consisting of Glasgow Coma Score (GCS) and brain stem reflexes, and SEP were performed 24, 48, and 72 h after CPR. Positive predictive values for predicting absent and present SEP, as well as diagnostic accuracy were calculated. Data of 407 patients were included. Of the 781 SEPs performed, N20 s were present in 401, bilaterally absent in 299, and 81 SEPs were technically undeterminable. The highest positive predictive values (0.63–0.91) for an absent SEP were found for absent pupillary light responses. The highest positive predictive values (0.71–0.83) for a present SEP were found for motor scores of withdrawal to painful stimuli or better. Multivariate analyses showed a fair diagnostic accuracy (0.78) for neurological examination in predicting an absent or present SEP at 48 or 72 h after CPR. This study shows that neurological examination cannot reliably predict absent or present cortical N20 responses in median nerve SEPs in patients after CPR

Embedded Sensors and Controls to Improve Component Performance and Reliability: Conceptual Design Report

The overall project objective is to demonstrate improved reliability and increased performance made possible by deeply embedding instrumentation and controls (I&C) in nuclear power plant components. The project is employing a highly instrumented canned rotor, magnetic bearing, fluoride salt pump as its I&C technology demonstration vehicle. The project s focus is not primarily on pump design, but instead is on methods to deeply embed I&C within a pump system. However, because the I&C is intimately part of the basic millisecond-by-millisecond functioning of the pump, the I&C design cannot proceed in isolation from the other aspects of the pump. The pump will not function if the characteristics of the I&C are not embedded within the design because the I&C enables performance of the basic function rather than merely monitoring quasi-stable performance. Traditionally, I&C has been incorporated in nuclear power plant (NPP) components after their design is nearly complete; adequate performance was obtained through over-design. This report describes the progress and status of the project and provides a conceptual design overview for the embedded I&C pump