Constraints on AGN accretion disc viscosity derived from continuum variability

We estimate a value of the viscosity parameter in AGN accretion discs for the PG quasar sample. We assume that optical variability on time-scales of months to years is caused by local instabilities in the inner accretion disc. Comparing the observed variability time-scales to the thermal time-scales of alpha-disc models we obtain constraints on the viscosity parameter for the sample. We find that, at a given L/L_Edd, the entire sample is consistent with a single value of the viscosity parameter, alpha. We obtain constraints of 0.01 < alpha < 0.03 for 0.01 < L/L_Edd < 1.0. This narrow range suggests that these AGN are all seen in a single state, with a correspondingly narrow spread of black hole masses or accretion rates. The value of alpha we derive is consistent with predictions by current simulation s in which MHD turbulence is the primary viscosity mechanism.Comment: 7 pages, 5 figures. Accepted for publication in Monthly Notices of the Royal Astronomical Societ

The mediation of social influences on smoking cessation and awareness of the early signs of lung cancer

Background Whilst there has been no clear consensus on the potential for earlier diagnosis of lung cancer, recent research has suggested that the time between symptom onset and consultation can be long enough to plausibly affect prognosis. In this article, we present findings from a qualitative study involving in-depth interviews with patients who had been diagnosed with lung cancer (n = 11), and people who were at heightened risk of developing the disease (n = 14). Methods A grounded theory methodology was drawn upon to conduct thematic and narrative based approaches to analysis. Results The paper focuses on three main themes which emerged from the study: i) fatalism and resignation in pathways to help-seeking and the process of diagnosis; ii) Awareness of smoking risk and response to cessation information and advice. iii) The role of social and other networks on help-seeking. Key findings included: poor awareness among participants of the symptoms of lung cancer; ambivalence about the dangers of smoking; the perception of lung cancer as part of a homogenisation of multiple illnesses; close social networks as a key trigger in help-seeking. Conclusions We suggest that future smoking cessation and lung cancer awareness campaigns could usefully capitalise on the influence of close social networks, and would benefit from taking a ‘softer’ approach

Planet Formation Imager (PFI): science vision and key requirements

The Planet Formation Imager (PFI) project aims to provide a strong scientific vision for ground-based optical astronomy beyond the upcoming generation of Extremely Large Telescopes. We make the case that a breakthrough in angular resolution imaging capabilities is required in order to unravel the processes involved in planet formation. PFI will be optimised to provide a complete census of the protoplanet population at all stellocentric radii and over the age range from 0.1 to ~100 Myr. Within this age period, planetary systems undergo dramatic changes and the final architecture of planetary systems is determined. Our goal is to study the planetary birth on the natural spatial scale where the material is assembled, which is the "Hill Sphere" of the forming planet, and to characterise the protoplanetary cores by measuring their masses and physical properties. Our science working group has investigated the observational characteristics of these young protoplanets as well as the migration mechanisms that might alter the system architecture. We simulated the imprints that the planets leave in the disk and study how PFI could revolutionise areas ranging from exoplanet to extragalactic science. In this contribution we outline the key science drivers of PFI and discuss the requirements that will guide the technology choices, the site selection, and potential science/technology tradeoffs.S.K. acknowledges support from an STFC Rutherford Fellowship (ST/J004030/1) and Philip Leverhulme Prize (PLP-2013-110). Part of this work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration

Disk Evolution: Testing the Foundations

<p>Models for planet formation and observable large-scale structure in protoplanetary disks are built on a foundation of gas-phase physics. In the simplest telling, it is assumed that the disk evolves due to turbulence, and that photoevaporation is the<br> dominant driver of mass loss. How secure is this foundation to our understanding? I will review recent results from magnetohydrodynamic simulations of protoplanetary disks, which suggest a modified picture in which MHD winds and fossil magnetic flux play a critical role. I will discuss what these theoretical results may imply for observations of disks.</p

Making personal travel planning work: Case studies

Integrated Transport Planning Ltd. Report to Department for Transpor

Making personal travel planning work: Research report

Integrated Transport Planning Lt

Data underpinning Olivia Rachel Armitage's thesis

The data files are embargoed until 01/05/202