Evaporation of Concentrated Polymer Solutions is Insensitive to Relative Humidity

A recent theory suggests that the evaporation kinetics of macromolecular solutions is insensitive to the ambient relative humidity (RH) due to the formation of a ‘polarisation layer’ of solutes at the air-solution interface. We confirm this insensitivity up to RH ≈ 80% in the evaporation of polyvinylalcohol solutions from open-ended capillaries. To explain the observed drop in evaporation rate at higher RH, we need to invoke compressive stresses due to interfacial polymer gelation. Moreover, RH-insensitive evaporation sets in earlier than theory predicts, suggesting a further role for a gelled ‘skin’. We discuss the relevance of these observations for respiratory virus transmission via aerosols

Assessing the performance of social spending in Europe

Based on the construction of a new composite index to assess the relative performance of welfare policies, we show that the variability of performances cannot be explained only by the amount of resources devoted to social policies, but also by its composition: countries with higher shares of social public expenditure, specifically aimed at reducing income concentration, obtain better results. This associates the traditional classification of the welfare systems to the performance obtained in the social sector

The evaporation of concentrated polymer solutions is insensitive to relative humidity

A recent theory suggests that the evaporation kinetics of macromolecular solutions is insensitive to the ambient relative humidity (RH) due to the formation of a `polarisation layer' of solutes at the air-solution interface. We confirm this insensitivity up to RH~80% in the evaporation of polyvinyl alcohol solutions from open-ended capillaries. To explain the observed drop in evaporation rate at higher RH, we need to invoke compressive stresses due to interfacial polymer gelation. Moreover, RH-insensitive evaporation sets in earlier than theory predicts, suggesting a further role for a gelled `skin'. We discuss the relevance of these observations for respiratory virus transmission via aerosols.Comment: Accepted in PR

Tracking the stochastic growth of bacterial populations in microfluidic droplets

Bacterial growth in microfluidic droplets is relevant in biotechnology, in microbial ecology, and in understanding stochastic population dynamics in small populations. However, it has proved challenging to automate measurement of absolute bacterial numbers within droplets, forcing the use of proxy measures for population size. Here we present a microfluidic device and imaging protocol that allows high-resolution imaging of thousands of droplets, such that individual bacteria stay in the focal plane and can be counted automatically. Using this approach, we track the stochastic growth of hundreds of replicate Escherichia coli populations within droplets. We find that, for early times, the statistics of the growth trajectories obey the predictions of the Bellman-Harris model, in which there is no inheritance of division time. Our approach should allow further testing of models for stochastic growth dynamics, as well as contributing to broader applications of droplet-based bacterial culture

Diffusive evaporation dynamics in polymer solutions is ubiquitous

Recent theory and experiments have shown how the buildup of a high-concentration polymer layer at a one-dimensional solvent-air interface can lead to an evaporation rate that scales with time as $t^{-1/2}$ and that is insensitive to the ambient humidity. Using phase field modelling we show that this scaling law constitutes a naturally emerging robust regime, Diffusion-Limited Evaporation (DLE). This regime dominates the dynamical state diagram of the system, which also contains regions of constant and arrested evaporation, confirming and extending understanding of recent experimental observations and theoretical predictions. We provide a theoretical argument to show that the scaling observed in the DLE regime occurs for a wide range of parameters, and our simulations predict that it can occur in two-dimensional geometries as well. Finally, we discuss possible extensions to more complex systems.Comment: 6 pages, 4 figure

Healthcare choice: Discourses, perceptions, experiences and practices

Policy discourse shaped by neoliberal ideology, with its emphasis on marketisation and competition, has highlighted the importance of choice in the context of healthcare and health systems globally. Yet, evidence about how so-called consumers perceive and experience healthcare choice is in short supply and limited to specific healthcare systems, primarily in the Global North. This special issue aims to explore how choice is perceived and utilised in the context of different systems of healthcare throughout the world, where choice, at least in policy and organisational terms, has been embedded for some time. The articles are divided into those emphasising: embodiment and the meaning of choice; social processes associated with choice; the uncertainties, risks and trust involved in making choices; and issues of access and inequality associated with enacting choice. These sociological studies reveal complexities not always captured in policy discourse and suggest that the commodification of healthcare is particularly problematic

Sparrows can't sing : East End kith and kinship in the 1960s

Sparrows Can’t Sing (1963) was the only feature film directed by the late and much lamented Joan Littlewood. Set and filmed in the East End, where she worked for many years, the film deserves more attention than it has hitherto received. Littlewood’s career spanned documentary (radio recordings made with Ewan MacColl in the North of England in the 1930s) to directing for the stage and the running of the Theatre Royal in London’s Stratford East, often selecting material which aroused memories in local audiences (Leach 2006: 142). Many of the actors trained in her Theatre Workshop subsequently became better known for their appearances on film and television. Littlewood herself directed hardly any material for the screen: Sparrows Can’t Sing and a 1964 series of television commercials for the British Egg Marketing Board, starring Theatre Workshop’s Avis Bunnage, were rare excursions into an area of practice which she found constraining and unamenable (Gable 1980: 32). The hybridity and singularity of Littlewood’s feature may answer, in some degree, for its subsequent neglect. However, Sparrows Can’t Sing makes a significant contribution to a group of films made in Britain in the 1960s which comment generally on changes in the urban and social fabric. It is especially worthy of consideration, I shall argue, for the use which Littlewood made of a particular community’s attitudes – sentimental and critical – to such changes and for its amalgamation of an attachment to documentary techniques (recording an aural landscape on location) with a preference for nonnaturalistic delivery in performance