University of Exeter

About: University of Exeter is a education organization based out in Exeter, United Kingdom. It is known for research contribution in the topics: Population & Context (language use). The organization has 15820 authors who have published 50650 publications receiving 1793046 citations. The organization is also known as: Exeter University & University of the South West of England.

The nonlinear development of Gortler vortices in growing boundary layers

Abstract: The Growth of Gortler vortices in boundary layers on concave walls is investigated. It is shown that for vortices of wavelength comparable to the boundary-layer thickness the appropriate linear stability equations cannot be reduced to ordinary differential equations. The partial differential equations governing the linear stability of the flow are solved numerically, and neutral stability is defined by the condition that a dimensionless energy function associated with the flow should have a maximum or minimum when plotted as a function of the downstream variable X. The position of neutral stability is found to depend on how and where the boundary layer is perturbed, so that the concept of a unique neutral curve so familiar in hydrodynamic-stability theory is not tenable in the Gortler problem, except for asymptotically small wavelengths. The results obtained are compared with previous parallel-flow theories and the small-wavelength asymptotic results of Hall (1982a, b), which are found to be reasonably accurate even for moderate values of the wavelength. The parallel-flow theories of the growth of Gortler vortices are found to be irrelevant except for the small-wavelength limit. The main deficiency of the parallel-flow theories is shown to arise from the inability of any ordinary differential approximation to the full partial differential stability equations to describe adequately the decay of the vortex at the edge of the boundary layer. This deficiency becomes intensified as the wavelength of the vortices increases and is the cause of the wide spread of the neutral curves predicted by parallel-flow theories. It is found that for a wall of constant radius of curvature a given vortex imposed on the flow can grow for at most a finite range of values of X. This result is entirely consistent with, and is explicable by the asymptotic results of, Hall (1982a).

Keep off the grass? Cannabis, cognition and addiction

Abstract: In an increasing number of states and countries, cannabis now stands poised to join alcohol and tobacco as a legal drug. Quantifying the relative adverse and beneficial effects of cannabis and its constituent cannabinoids should therefore be prioritized. Whereas newspaper headlines have focused on links between cannabis and psychosis, less attention has been paid to the much more common problem of cannabis addiction. Certain cognitive changes have also been attributed to cannabis use, although their causality and longevity are fiercely debated. Identifying why some individuals are more vulnerable than others to the adverse effects of cannabis is now of paramount importance to public health. Here, we review the current state of knowledge about such vulnerability factors, the variations in types of cannabis, and the relationship between these and cognition and addiction.

An open letter to The BMJ editors on qualitative research

Abstract: Seventy six senior academics from 11 countries invite The BMJ ’s editors to reconsider their policy of rejecting qualitative research on the grounds of low priority. They challenge the journal to develop a proactive, scholarly, and pluralist approach to research that aligns with its stated mission

Acceptability, benefits, and challenges of video consulting: a qualitative study in primary care.

Abstract: Background People increasingly communicate online, using visual communication mediums such as Skype and FaceTime. Growing demands on primary care services mean that new ways of providing patient care are being considered. Video consultation (VC) over the internet is one such mode. Aim To explore patients’ and clinicians’ experiences of VC. Design and setting Semi-structured interviews in UK primary care. Method Primary care clinicians were provided with VC equipment. They invited patients requiring a follow-up consultation to an online VC using the Attend Anywhere web-based platform. Participating patients required a smartphone, tablet, or video-enabled computer. Following VCs, semi-structured interviews were conducted with patients (n = 21) and primary care clinicians (n = 13), followed by a thematic analysis. Results Participants reported positive experiences of VC, and stated that VC was particularly helpful for them as working people and people with mobility or mental health problems. VCs were considered superior to telephone consultations in providing visual cues and reassurance, building rapport, and improving communication. Technical problems, however, were common. Clinicians felt, for routine use, VCs must be more reliable and seamlessly integrated with appointment systems, which would require upgrading of current NHS IT systems. Conclusion The visual component of VCs offers distinct advantages over telephone consultations. When integrated with current systems VCs can provide a time-saving alternative to face-to-face consultations when formal physical examination is not required, especially for people who work. Demand for VC services in primary care is likely to rise, but improved technical infrastructure is required to allow VC to become routine. However, for complex or sensitive problems face-to-face consultations remain preferable.