Very fast X-ray spectral variability in Cygnus X-1: Origin of the hard and soft-state emission components

The way in which the X-ray photon index, {\Gamma}, varies as a function of count rate is a strong diagnostic of the emission processes and emission geometry around accreting compact objects. Here we present the results from a study using a new, and simple, method designed to improve sensitivity to the measurement of the variability of {\Gamma} on very short time-scales. We have measured {\Gamma} in ~2 million spectra, extracted from observations with a variety of different accretion rates and spectral states, on time-scales as short as 16 ms for the high mass X-ray binary Cygnus X-1, and have cross-correlated these measurements with the source count rate. In the soft-state cross-correlation functions (CCFs) we find a positive peak at zero lag, stronger and narrower in the softer observations. Assuming that the X-rays are produced by Compton scattering of soft seed photons by high energy electrons in a corona, these results are consistent with Compton cooling of the corona by seed photons from the inner edge of the accretion disc, the truncation radius of which increases with increasing hardness ratio. The CCFs produced from the hard-state observations, however, show an anti-correlation which is most easily explained by variation in the energy of the electrons in the corona rather than in variation of the seed photon flux. The hard-state CCFs can be decomposed into a narrow anti-correlation at zero lag, which we tentatively associate with the effects of self-Comptonisation of cyclo-synchrotron seed photons in either a hot, optically thin accretion flow or the base of the jet, and a second, asymmetric component which we suggest is produced as a consequence of a lag between the soft and hard X-ray emission. The lag may be caused by a radial temperature/energy gradient in the Comptonising electrons combined with the inward propagation of accretion rate perturbations.Comment: 12 pages, 14 figures; accepted for publication in Monthly Notices of the Royal Astronomical Society, 2013 June

Decision tree rating scales for workload estimation: Theme and variations

The Modified Cooper-Harper (MCH) scale which is a sensitive indicator of workload in several different types of aircrew tasks was examined. The study determined if variations of the scale might provide greater sensitivity and the reasons for the sensitivity of the scale. The MCH scale and five newly devised scales were examined in two different aircraft simulator experiments in which pilot loading was treated as an independent variable. It is indicated that while one of the new scales may be more sensitive in a given experiment, task dependency is a problem. The MCH scale exhibits consistent senstivity and remains the scale recommended for general use. The MCH scale results are consistent with earlier experiments. The rating scale experiments are reported and the questionnaire results which were directed to obtain a better understanding of the reasons for the relative sensitivity of the MCH scale and its variations are described

The role of feedback in young people’s academic choices

Women are underrepresented in Science, Technology, Engineering and Mathematics subjects with more girls leaving these subjects at every stage in education. The current research used a scenario methodology to examine the impact of teacher feedback on girls’ and boys’ choices to study a specific science subject, engineering. British participants aged 13 (N = 479) were given scenarios where a new teacher encouraged them to take engineering using person feedback which focussed on their abilities, process feedback which focussed on their effort levels or gave them no reason. Results suggested that both boys and girls were more likely to select to study engineering when they received person feedback rather than process or no feedback. Young people also thought that ability was more important to being successful in science than in non-science subjects.This suggests young people feel that ability is needed to succeed in science subjects and person feedback can lead them to believe that they have this ability. Therefore, teacher feedback which gives ability attributions for possible success could be used to encourage more young people to persist in science. However, the potentially negative longer term outcomes of ability attributions and how they may be negated are also discussed

Knowledge mobilization: stepping into interdependent and relational space using co-creation

In recent years, there has been a growing interest in using co-creation approaches, with academics and partners working together to create research and interventions to achieve impact. Action research typically starts with the question ‘how can we improve this situation?’ and then co-creates knowledge with and not on or for people. This approach contrasts with conventional approaches in which academics create knowledge and then disseminate it to users via conferences, reports etc. The co-creative approach involves a shift in academics’ thinking and approaches. The success of co-creation depends on the academic shifting from being self-focussed and independent to being other-focussed and interdependent. In this paper, we outline the theoretical background that has informed our thinking and practices related to knowledge mobilization, and our novel relational approach. We illustrate our approach using two co-created projects, focused on enhancing early literacy and supporting mothers with substance use problems. We hope that this will help others consider when it may be appropriate to use a co-creative approach and how to engage in this co-creation process, including awareness of common barriers and benefits

Remoulding of the Mercia Mudstone Group around CFA pile shafts

A field test has been undertaken to investigate changes to in situ Mercia Mudstone at the pile soil interface after installation of four 5.5 m long 350 mm diameter CFA piles. The test investigated whether a remoulded zone exists, the extent of the zone, changes caused by remoulding and the effect of the installation method. The piles and surrounding soil were excavated after installation to a depth of just under 2 m. The sections of pile and surrounding soil were returned to the laboratory where a variety of detailed observations at both micro and macroscopic scales were undertaken, together with chemical and mineralogical analysis. It was found that a remoulded zone existed in all piles but that this varied in thickness both laterally and vertically around a pile. Across all piles the maximum thickness observed was 55 mm. The average thickness, fabric and texture were all affected by installation method. A distinctive vertically orientated fabric was observed in which up to four vertically orientated layers could be distinguished. There was evidence of changes in texture/fabric, structure, colour, mineralogy and chemistry

AN ANALYSIS ON THE EFFECTS OF ADDITIVE MANUFACTURING (AM) ON F/A-18E/F READINESS

This research paper focuses on the Boeing F/A-18E and the F/A-18F Super Hornet aviation depot level repairable (AVDLR) parts process and the potential effects of additive manufacturing (AM) on that process. The motivation for study was spurred by recent reports indicating that the F/A-18E/F is experiencing decreased operational readiness due to increases in maintenance-related impacts related to parts availability, long lead times, and increased parts failure frequency. This study aimed to determine the requirements for interjecting AM into the Intermediate level repair process in order to make a significant impact on  F/A-18E/F depot-level repairable part lead times. More specifically, this research analyzes the potential impact of various AM production levels on overall lead times. Facilitation of this research project was accomplished through mathematical modeling and by conducting simulations based on various assumptions and probability distributions. Eight simulations were conducted, each with different AM production time assumptions. Resultant outputs reflected 19 different scenarios simulating 0%–90% production of AM at the Intermediate Maintenance level. Results indicate that AM has the potential to decrease overall expected lead time averages if AM production can be kept to less than approximately 30 days.Lieutenant, United States NavyLieutenant, United States NavyLieutenant Commander, United States NavyApproved for public release. Distribution is unlimited

Carbon Free Boston: Technical Summary

Part of a series of reports that includes: Carbon Free Boston: Summary Report; Carbon Free Boston: Social Equity Report; Carbon Free Boston: Buildings Technical Report; Carbon Free Boston: Transportation Technical Report; Carbon Free Boston: Waste Technical Report; Carbon Free Boston: Energy Technical Report; Carbon Free Boston: Offsets Technical Report; Available at http://sites.bu.edu/cfb/OVERVIEW: This technical summary is intended to argument the rest of the Carbon Free Boston technical reports that seek to achieve this goal of deep mitigation. This document provides below: a rationale for carbon neutrality, a high level description of Carbon Free Boston’s analytical approach; a summary of crosssector strategies; a high level analysis of air quality impacts; and, a brief analysis of off-road and street light emissions.Published versio