• Ageing, old age and older adults: a social media analysis of dominant topics and discourses

      Makita, Meiko; Mas-Bleda, Amalia; Stuart, Emma; Thelwall, Mike (Cambridge University Press (CUP), 2019-08-13)
      Whilst representations of old age and older people in traditional media have been well documented, examinations of such representations within social media discourse are still scarce. This is an unfortunate omission because of the importance of social media for communication in contemporary society. In this study, we combine content analysis and discourse analysis to explore patterns of representation on Twitter around the terms ageing, old age, older people and elderly with a sample of 1,200 tweets. Our analysis shows that ‘personal concerns/views’ and ‘health and social care’ are the predominant overall topics, although some topics are clearly linked with specific keywords. The language often used in the tweets seems to reinforce negative discourses of age and ageing that locate older adults as a disempowered, vulnerable and homogeneous group; old age is deemed a problem and ageing is considered something that needs to be resisted, slowed or disguised. These topics and discursive patterns are indeed similar to those found in empirical studies of social perceptions and traditional media portrayal of old age, which indicates that social media and Twitter in particular appears to serve as an online platform that reproduces and reinforces existing ageist discourses in traditional media that feed into social perceptions of ageing and older people.
    • Combined free-stream disturbance measurements and receptivity studies in hypersonic wind tunnels by means of a slender wedge probe and direct numerical simulation

      Wagner, Alexander; Schülein, Erich; Petervari, René; Hannemann, Klaus; Ali, Syed RC; Cerminara, Adriano; Sandham, Neil D (Cambridge University Press (CUP), 2018-03-13)
      Combined free-stream disturbance measurements and receptivity studies in hypersonic wind tunnels were conducted by means of a slender wedge probe and direct numerical simulation. The study comprises comparative tunnel noise measurements at Mach 3, 6 and 7.4 in two Ludwieg tube facilities and a shock tunnel. Surface pressure fluctuations were measured over a wide range of frequencies and test conditions including harsh test environments not accessible to measurement techniques such as Pitot probes and hot-wire anemometry. A good agreement was found between normalized Pitot pressure fluctuations converted into normalized static pressure fluctuations and the wedge probe readings. Quantitative results of the tunnel noise are provided in frequency ranges relevant for hypersonic boundary-layer transition. Complementary numerical simulations of the leading-edge receptivity to fast and slow acoustic waves were performed for the applied wedge probe at conditions corresponding to the experimental free-stream conditions. The receptivity to fast acoustic waves was found to be characterized by an early amplification of the induced fast mode. For slow acoustic waves an initial decay was found close to the leading edge. At all Mach numbers, and for all considered frequencies, the leading-edge receptivity to fast acoustic waves was found to be higher than the receptivity to slow acoustic waves. Further, the effect of inclination angles of the acoustic wave with respect to the flow direction was investigated. An inclination angle was found to increase the response on the wave-facing surface of the probe and decrease the response on the opposite surface for fast acoustic waves. A frequency-dependent response was found for slow acoustic waves. The combined numerical and experimental approach in the present study confirmed the previous suggestion that the slow acoustic wave is the dominant acoustic mode in noisy hypersonic wind tunnels.
    • Constructing and negotiating social participation in old age: Experiences of older adults living in urban environments in the United Kingdom

      Woolrych, Ryan; Sixsmith, Judith; Fisher, Jenny; Makita, Meiko; Lawthom, Rebecca; Murray, Michael (Cambridge University Press (CUP), 2019-12-23)
      The age-friendly cities and communities movement has focused on how to better support older adults to age well within urban environments. Central to 'ageing well' and 'active ageing' agendas is ensuring that older adults can participate in meaningful forms of social participation. The benefits of social participation in old age have been well documented, and research amongst community-dwelling older adults has explored some of the neighbourhood qualities that facilitate or impede such forms of engagement. However, understandings of how older adults construct and negotiate social participation within everyday urban environments have been largely unexplored. To address this gap, we present results from 104 interviews conducted with older adults living in three cities and nine neighbourhoods in the United Kingdom (UK). The findings explore three themes generated from the research: 'constructing meaningful social participation in old age', 'negotiating access to social participation' and 'navigating home and community'. Across these themes, the paper describes how experiences of social participation in old age involve a number of inter-connected physical, psychological and social processes experienced by individuals across a range of environmental settings including the home, outdoor spaces and community facilities. The paper concludes by discussing the implications of the findings for practice, specifically in the delivery of age-friendly communities.
    • Transition mechanisms in cross-flow-dominated hypersonic flows with free-stream acoustic noise

      Cerminara, Adriano; Sandham, Neil (Cambridge University Press (CUP), 2020-06-04)
      Transition to turbulence in high-speed flows is determined by multiple parameters, many of which are not fully understood, leading to problems in developing physics-based prediction methods. In this contribution, we compare transition mechanisms in configurations with unswept and swept leading edges that are exposed to free-stream acoustic disturbances. Direct numerical simulations are run at a Mach number of six with the same free-stream noise, consisting of either fast or slow acoustic disturbances, with two different amplitudes to explore the linear and nonlinear aspects of receptivity and transition. For the unswept configuration, receptivity follows an established mechanism involving synchronisation of fast acoustic disturbances with boundary-layer modes. At high forcing amplitudes, transition proceeds via the formation of streaks and their eventual breakdown. In the swept case, the process of streak-induced transition is modified by the presence of a cross-flow instability in the leading-edge region. Linear stability analysis confirms the presence of a cross-flow mode as well as weaker first and second mode waves. Both fast and slow types of forcing independently stimulate an unusual transition mechanism involving significantly narrower streaks than those arising from the cross-flow instability behind the swept leading edge or those induced nonlinearly in the unswept case. In the observed transition process, the cross-flow mode leads to a thin layer of streamwise vorticity that breaks up under the influence of high spanwise wavenumber disturbances. These disturbances first appear in the leading-edge region.