Choice of FDMA/SCPC access technique for aeronautical satellite voice system

A worldwide aeronautical mobile satellite system is about to become operational. The system architecture and access methods have been debated extensively, resulting in the selection of Time Division Multiplexing/Time Division Multiple Access (TDM/TDMA) access for packet data, and Single Channel Per Carrier (SCPC) for voice. These have become standards for airline use, and also satisfy the known requirements of ICAO for safety related communications. Voice communications are expected to absorb a high proportion of satellite bandwidth and power in the future. Here, it is explained why INMARSAT selected Frequency Division Multiple Access/SCPC satellite access for this application

Geo-cultural influences and critical factors in inter-firm collaboration

Inter-firm collaboration and other forms of inter-organisational activity are increasingly the means by which technological innovation occurs. This paper draws on evidence from two studies of the same set of firms to examine the conduct of collaborations over time across different contexts. The purpose is to examine the critical factors associated with successful collaboration and explore the importance of the geo-cultural context in understanding the conduct of inter-firm collaboration. The conceptual framework draws on two main sources: - Storper’s concept of ‘conventions’ of identity and participation and Lorenz’s classification of different types of knowledge. These are used to indicate the kinds and sources of adjustments required for successful collaboration

Long-term change in benthopelagic fish abundance in the abyssal northeast Pacific Ocean

Food web structure, particularly the relative importance of bottom-up and top-down control of animal abundances, is poorly known for the Earth's largest habitats: the abyssal plains. A unique 15-yr time series of climate, productivity, particulate flux, and abundance of primary consumers (primarily echinoderms) and secondary consumers (fish) was examined to elucidate the response of trophic levels to temporal variation in one another. Towed camera sled deployments in the abyssal northeast Pacific (4100 m water depth) showed that annual mean numbers of the dominant fish genus (Coryphaenoides spp.) more than doubled over the period 1989-2004. Coryphaenoides spp. abundance was significantly correlated with total abundance of mobile epibenthic megafauna (echinoderms), with changes in fish abundance lagging behind changes in the echinoderms. Direct correlations between surface climate and fish abundances, and particulate organic carbon (POC) flux and fish abundances, were insignificant, which may be related to the varied response of the potential prey taxa to climate and POC flux. This Study provides a fare opportunity to study the long-term dynamics of an unexploited marine fish population and Suggests a dominant role for bottom-up control in this system

A Census of the Carina Nebula -- II. Energy Budget and Global Properties of the Nebulosity

The first paper in this series took a direct census of energy input from the known OB stars in the Carina Nebula, and in this paper we study the global properties of the surrounding nebulosity. We find that the total IR luminosity of Carina is about 1.2E7 Lsun, accounting for only about 50-60% of the known stellar luminosity from Paper I. Similarly, the ionizing photon luminosity -- (abridged; many important details omitted). Synchronized star formation around the periphery of Carina provides a strong case that star formation here was indeed triggered by stellar winds and UV radiation. This second generation appears to involve a cascade toward preferentially intermediate- and low-mass stars, but this may soon change when eta Car and its siblings explode. If the current reservoir of atomic and molecular gas can be tapped at that time, massive star formation may be rejuvinated around the periphery of Carina much as if it were a young version of Gould's Belt. Also, when these multiple SNe occur, the triggered second generation will be pelted repeatedly with SN ejecta bearing short-lived radioactive nuclides. Carina may therefore represent the most observable analog to the cradle of our own Solar System.Comment: MNRAS accepted, 14 pages, fig 1 in colo

Adherence to prophylaxis in adolescents and young adults with severe haemophilia, A qualitative study with patients

© 2018 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.Abstract Introduction: Reported levels of adherence to prophylaxis among young people with haemophilia (YPH) vary widely and are predominately based on estimations made by healthcare professionals and parents. Reasons for (non)adherence among YPH in particular have not been evidenced. Aim: to examine experiences in relation to prophylaxis with YPH themselves, and barriers and facilitators to their adherence. Methods: 11 Participants were recruited in five haemophilia centres across England and Wales. All patients who met the inclusion criteria (aged 12-25, diagnosed with haemophilia, on prophylaxis) were approached during a routine check-up appointment, and all participants who agreed to take part were interviewed. Interviews were audio recorded, transcribed and analysed using Interpretative Phenomenological Analysis. Results: Self-reported adherence to prophylaxis was good. Few participants admitted to intentionally skipping injections although they reported sometimes forgetting. However, due to the increasingly personalised and flexible approach to prophylaxis, adherence is not straightforward to define. Barriers to adherence included a busy lifestyle, dislike of the intravenous injection, venous access issues, anxiety or stress and being out of one’s normal routine. Support was an important facilitator to adherence, including support from health professionals at the haemophilia centre as well as friends. Parents appear to be very involved with their sons’ haemophilia management, even after their sons leave home. Conclusion: What this study adds is that the increasingly flexible and personalized approach to managing prophylaxis in haemophilia may sometimes lead to confusion around treatment frequency and dosing. This may lead to accidental non-adherence, which is distinct from both skipping and forgetting. Advice from haemophilia teams may not always be consistent, and is likely to be interpreted differently by different individuals. Some additional training and education of patients and their families to increase their knowledge and skills around prophylaxis may reduce this confusion and therefore is likely to improve adherence further.Peer reviewedFinal Published versio

“Do I look fat?” Self-perceived body weight and labor market outcomes

Research reporting that greater body weight is associated with lower wages and employment, particularly among women, focuses on how employers perceive workers. In contrast, we examine whether workers’ own perceptions of body weight influence labor market outcomes. Numerous studies find that misperception of body weight influences health behaviors and health, both mental and physical. For example, anorexia nervosa involves the over-perception of weight and raises the risk of cardiovascular disease. Do the health consequences of inaccurate self-perceived weight carry through to the labor market? We use the National Longitudinal Survey of Youth 1997 (NLSY97) to investigate patterns in weight misperception and three labor market outcomes. We find little evidence that either over-perception or under-perception of weight is associated with wages, weeks worked, or the number of jobs held for women and men.Accepted manuscrip

The association between socioeconomic status and adult fast-food consumption in the U.S.

Health follows a socioeconomic status (SES) gradient in developed countries, with disease prevalence falling as SES rises. This pattern is partially attributed to differences in nutritional intake, with the poor eating the least healthy diets. This paper examines whether there is an SES gradient in one specific aspect of nutrition: fast-food consumption. Fast food is generally high in calories and low in nutrients. We use data from the 2008, 2010, and 2012 waves of the National Longitudinal Survey of Youth (NLSY79) to test whether adult fast-food consumption in the United States falls as monetary resources rise (n = 8136). This research uses more recent data than previous fast-food studies and includes a comprehensive measure of wealth in addition to income to measure SES. We find little evidence of a gradient in adult fast-food consumption with respect to wealth. While adults in the highest quintile are 54.5% less likely to report fast-food consumption than those in the lowest quintile, adults in the second and third quintiles are no less likely to report fast food–food intake than the poorest. Contrary to popular belief, fast-food consumption rises as income rises from the lowest to middle quintiles. The variation in adult fast-food consumption across income and wealth groups is, however, small. Those in the wealthiest quintile ate about one less fast-food meal on average than those in the lowest quintile. Other factors play a bigger role in explaining fast-food consumption: reading ingredient labels is negatively associated while soda consumption and hours of work are positively associated with fast-food consumption.Accepted manuscrip