Non-equilibrium melting of colloidal crystals in confinement

We report on a novel and flexible experiment to investigate the non-equilibrium melting behaviour of model crystals made from charged colloidal spheres. In a slit geometry polycrystalline material formed in a low salt region is driven by hydrostatic pressure up an evolving gradient in salt concentration and melts at large salt concentration. Depending on particle and initial salt concentration, driving velocity and the local salt concentration complex morphologic evolution is observed. Crystal-melt interface positions and the melting velocity are obtained quantitatively from time resolved Bragg- and polarization microscopic measurements. A simple theoretical model predicts the interface to first advance, then for balanced drift and melting velocities to become stationary at a salt concentration larger than the equilibrium melting concentration. It also describes the relaxation of the interface to its equilibrium position in a stationary gradient after stopping the drive in different manners. We further discuss the influence of the gradient strength on the resulting interface morphology and a shear induced morphologic transition from polycrystalline to oriented single crystalline material before melting

Working Futures 2017-2027 : Long-run labour market and skills projections headline report

This report provides a concise overview of Working Futures 2017-2027 results for the UK. It presents historical trends and future prospects by sector for the UK and its constituent nations and the English regions. The prime focus of Working Futures is on the demand for skills as measured by employment by occupation and qualification, although the supply side is also considered. Its prime objective is to provide useful labour market information that can help to inform policy development and strategy around skills, careers and employment, for both policy makers and a much wider audience. The results are intended to provide a sound statistical foundation for reflection and debate among all those with an interest in the demand for and supply of skills. It is aimed at the general reader and focuses on the key messages from this very detailed study. It complements the more detailed outputs and results from the project available from the gov.uk website2 and cover sectors, occupations, geography and qualifications

Demographic and contextual infl uences in injury risk among adolescents in a low-income country setting: Results from a school-based survey in Tanzania

Objective: This study investigated the social, demographic and contextual factors associated with injury among adolescents in a low-income urban sub-Saharan African setting.Methods: Data on 2 176 adolescents aged 11–16 years were divided into three groups: Those that reported not being injured, those that had been injured once, and those that had been injured multiple times within a 12-month recall period. We conducted bivariate analyses to screen for associations with several social, demographic and contextual factors. Then a multinomial logistic regression was performed to examine associations while adjusting for covariates.Results: Within the recall period, 22.14% of participants reported one serious injury and 10.96% reported multiple injuries. Compared with non-injured participants, those injured two or more times were mainly male (relative risk ratio (RRR) = 1.71 [1.27–2.31]), younger (RRR = 0.77 [0.68–0.86]), depressed (RRR = 1.98 [1.43–2.74]) and had high rates of truancy (RRR = 2.56; CI = 1.71–3.84). A travel time of more than 30 minutes to and from school was also associated with increased rates of injury (RRR = 1.61; CI = 1.13–2.29).Conclusions: Injuries are an important source of morbidity among school-attending adolescents in Dar es Salaam. The findings support more research into the contextual factors that predispose adolescents to excessive injury in the region. School settings have the potential to provide safety education in the region.Keywords: injury, sub-Saharan Africa, urban setting, school healt

Towards a mechanism for instability in channel flow of highly shear-thinning viscoelastic fluids

We consider the linear stability of channel flow of a shear-thinning viscoelastic fluid, replicating a instability recently discovered in experimental and theoretical work. We have extended the fluid model to allow for an inelastic shear-thinning stress component, and find that this additional contribution always has a stabilising influence on the instability. We conclude that, while shear-thinning is critical to the instability, the mechanism is primarily elastic

Onset of DNA Aggregation in Presence of Monovalent and Multivalent Counterions

We address theoretically aggregation of DNA segments by multivalent polyamines such as spermine and spermidine. In experiments, the aggregation occurs above a certain threshold concentration of multivalent ions. We demonstrate that the dependence of this threshold on the concentration of DNA has a simple form. When the DNA concentration c_DNA is smaller than the monovalent salt concentration, the threshold multivalent ion concentration depends linearly on c_DNA, having the form alpha c_DNA + beta. The coefficients alpha and beta are related to the density profile of multivalent counterions around isolated DNA chains, at the onset of their aggregation. This analysis agrees extremely well with recent detailed measurements on DNA aggregation in the presence of spermine. From the fit to the experimental data, the number of condensed multivalent counterions per DNA chain can be deduced. A few other conclusions can then be reached: i) the number of condensed spermine ions at the onset of aggregation decreases with the addition of monovalent salt; ii) the Poisson-Boltzmann theory over-estimates the number of condensed multivalent ions at high monovalent salt concentrations; iii) our analysis of the data indicates that the DNA charge is not over-compensated by spermine at the onset of aggregation.Comment: 12 pages, 8 figures. Biophysical Journal 2003, in pres

Risk Assessment and Management Associated with CCS

AbstractAs things stand, there is currently no available commercial insurance for long-term liability of CCS projects. This makes investors shy away from such initiatives, even if the risk of the venture is assessed to be relatively small. A policy review was carried out to assess the risks involved in the CCS industry which identified uncertainties with regards to the risks associated with CCS that make policy making and insuring CCS projects very difficult. This paper presents a coherent understanding of the chain of events that could lead to major failures in a CCS project. This research project has looked into the potential risks involved in CO2 storage and the ways in which their criticality and importance as well as their probability and likelihood can potentially be calculated using Fault Tree Analysis (FTA) and Analytical Hierarchy Process (AHP) methods