Digital control of the Kuiper Airborne Observatory telescope

The feasibility of using a digital controller to stabilize a telescope mounted in an airplane is investigated. The telescope is a 30 in. infrared telescope mounted aboard a NASA C-141 aircraft known as the Kuiper Airborne Observatory. Current efforts to refurbish the 14-year-old compensation system have led to considering a digital controller. A typical digital controller is modeled and added into the telescope system model. This model is simulated on a computer to generate the Bode plots and time responses which determine system stability and performance parameters. Important aspects of digital control system hardware are discussed. A summary of the findings shows that a digital control system would result in satisfactory telescope performance

Absolute continuity and spectral concentration for slowly decaying potentials

We consider the spectral function $\rho(\mu)$ $(\mu \geq 0)$ for the Sturm-Liouville equation $y^{''}+(\lambda-q)y =0$ on $[0,\infty)$ with the boundary condition $y(0)=0$ and where $q$ has slow decay $O(x^{-\alpha})$ $(a>0)$ as $x\to \infty$. We develop our previous methods of locating spectral concentration for $q$ with rapid exponential decay (JCAM 81 (1997) 333-348) to deal with the new theoretical and computational complexities which arise for slow decay

Extensions of a New Algorithm for the Numerical Solution of Linear Differential Systems on an Infinite Interval

This paper is part of a series of papers in which the asymptotic theory and appropriate symbolic computer code are developed to compute the asymptotic expansion of the solution of an n-th order ordinary differential equation. The paper examines the situation when the matrix that appears in the Levinson expansion has a double eigenvalue. Application is made to a fourth-order ODE with known special function solution

Alcohol and healthy ageing: a challenge for alcohol policy

Objectives: This paper presents findings of a qualitative study of older people's use of alcohol during retirement and identifies ways that an improved understanding of older people's drinking can inform policy approaches to alcohol and active and healthy ageing. Study design: Qualitative semi-structured interviews conducted with a self-selecting sample of retired people. Methods: Participants were recruited from three geographical locations in the West of Scotland. A quota sampling design was used to ensure a broad spread of participants in terms of socio-economic position, age and gender. In total 40 participants were interviewed and the data analysed thematically using Braun and Clarke's (2006) approach. Results: Amongst those who used alcohol, it was most often framed in terms of pleasure, relaxation, socialising and as a way to mark the passage of time. Alcohol was often associated with social occasions and interactions both in private and in public spaces. There were also many examples of the use of imposed routines to limit alcohol use and of a decreasing volume of alcohol being consumed as participants aged. This suggests that older people are often active in constructing what they regard as ‘healthier’ routines around alcohol use. However, processes and circumstances associated with ageing can lead to risk of social isolation and/or increased alcohol consumption. Such processes include retirement from paid work and other ‘biographical disruptions’ such as caring for a partner, bereavement and/or loss of social networks. Conclusions: These findings highlight processes that can result in changes in drinking habits and routines. Whilst these processes can be associated with a reduction or cessation of alcohol use as people age, they can also be associated with increased risk of harmful alcohol consumption. Fractured or disrupted routines, particularly those associated with bereavement or the burden of caring responsibilities, through increasing the risk of loneliness and isolation, can construct increased risk of harmful alcohol consumption. These findings reframe the pathway of risk between ageing and alcohol-related harm by highlighting the vulnerability to harmful drinking practices brought by fracture or sudden change of routine. The findings point to a role for public health in supporting the reconstruction of routines that provide structure and meaning and can be used to actively manage the benefits and harms associated with drinking

Insights on capitalism from Oceania

Purpose: The authors introduce the chapters of Engaging with Capitalism with a discussion of anthropological and other social theory about peoples' approaches to capitalism, especially peoples with vibrant noncapitalist social systems, such as are found in Oceania. Approach: The introduction is in the form of a review of anthropological and other social theory about interactions between capitalism and noncapitalist social systems. Findings: The theoretical literature has tended to dichotomize capitalist and noncapitalist societies. While heuristically it is useful to contrast capitalist and noncapitalist social systems, in practice once societies come into the orbit of capitalism people adapt elements of capitalism to suit their aims. Furthermore, societies generally considered thoroughly capitalist also include noncapitalist features. So it is more accurate to think of societies as involving a mix of capitalism and noncapitalism, and the nature of that mix is part of what makes each society distinct. Social implications: The theoretical dichotomization of societies as capitalist or not, with capitalism understood as being universal, and noncapitalism understood in general terms such as gift economy, is prevalent in public imaginaries. Domestic social policy and international development assistance are often based on this dualistic understanding. Such programs could work better if they were based instead on an understanding that each group of people has a dynamic economic system, which includes capitalist and noncapitalist elements that interact in ways influenced by their history and locality. Value of paper: The chapter provides a conceptual scaffold for thinking about the ways people engage with capitalism. © 2013 by Emerald Group Publishing Limited

Public Health Leadership In The 21st Century

Leadership in public health requires stretching the mind and soul in almost unimaginable ways. Living the dynamic tension of health as “part individual good served by medicine and part public good secured by public health activities” (Institute of Medicine, 2003a) represents a privilege and an awesome responsibility. Upholding the health of others requires complementing a foundation in science with skills in government, policy, media, economics, sociology, ethics and other dimensions. To survive and thrive, public health leaders must practice the “tactics of the transcendent” (Parks, 2005)