Droplet deformation and pumping in AC electro-osmotic micropumps

This paper was presented at the 2nd Micro and Nano Flows Conference (MNF2009), which was held at Brunel University, West London, UK. The conference was organised by Brunel University and supported by the Institution of Mechanical Engineers, IPEM, the Italian Union of Thermofluid dynamics, the Process Intensification Network, HEXAG - the Heat Exchange Action Group and the Institute of Mathematics and its Applications.This contribution deals with the pumping and deformation of oil in water droplets in alternating-current electro-osmotic micropumps. These micropumps are used to transport lowly conductive fluids through micro channels by means of a harmonically driven electrode array on the channel bottom. The periodic formation of an electric double layer above the electrodes results in an electro-osmotic flow, which carries along adjacent fluid layers. In experiments we observed that droplets immersed in the carrier fluid are transported by the channel flow and periodically deformed when passing the electrodes. Due to the different polarizability and conductivity of the droplet and the carrier fluid, dielectrophoretic forces act on the fluid droplet interface. These forces that are described by the Maxwell stress tensor increase with the electric field strength and attract the droplet towards the electrode. This contribution analyses the mechanisms of droplet pumping and deformation numerically by means of solving for the electric and the flow field to the two phases in the channel and by evaluating the dielectrophoretic forces on the droplet. A conservative level-set method is used to track the droplet surface accurately

Regulating pharmacists as contraception providers: a qualitative study from Coastal Kenya on injectable contraception provision to youth

Introduction Young people worldwide are often reticent to access family planning services from public health facilities: instead, they choose to get contraception from private, retail pharmacies. In Kenya, certain contraceptives are available in pharmacies: these include injectables, which can be dispensed but not administered, according national guidelines. However, Kenya struggles with enforcement of its pharmacy regulations and addressing illegal activity. Therefore, in this qualitative study, we assessed private pharmacies as an existing source of injectable contraception for young Kenyans (age 18–24), and investigated the perceived quality of service provision. Methods This study used: focus group discussions (6) with young community members; in-depth interviews (18) with youth who had purchased contraception from pharmacies; key informant interviews with pharmacy personnel and pharmacy stakeholders (25); and a mystery shopper (visiting 45 pharmacies). Results The study found that for injectable contraception, private pharmacies had expanded to service provision, and pharmacy personnel’s roles had transcended formal or informal training previously received–young people could both purchase and be injected in many pharmacies. Pharmacies were perceived to lack consistent quality or strong regulation, resulting in young clients, pharmacy personnel, and regulators being concerned about illegal activity. Participants’ suggestions to improve pharmacy service quality and regulation compliance focused on empowering consumers to demand quality service; strengthening regulatory mechanisms; expanding training opportunities to personnel in private pharmacies; and establishing a quality-based ‘brand’ for pharmacies. Discussion Kenya’s recent commitments to universal health coverage and interest in revising pharmacy policy provide an opportunity to improve pharmacy quality. Multi-pronged initiatives with both public and private partners are needed to improve pharmacy practice, update and enforce regulations, and educate the public. Additionally, the advent of self-administrable injectables present a new possible role for pharmacies, and could offer young clients a clean, discreet place to self-inject, with pharmacy personnel serving as educators and dispensers

The development of a new accountability measurement framework and tool for global health initiatives

The Global Strategy for Women's Children's and Adolescents' Health emphasizes accountability as essential to ensure that decision-makers have the information required to meet the health needs of their populations and stresses the importance of tracking resources, results, and rights to see 'what works, what needs improvement and what requires increased attention'. However, results from accountability initiatives are mixed and there is a lack of broadly applicable, validated tools for planning, monitoring and evaluating accountability interventions. This article documents an effort to transform accountability markers-including political will, leadership and the monitor-review-act cycle-into a measurement tool that can be used prospectively or retrospectively to plan, monitor and evaluate accountability initiatives. It describes the development process behind the tool including the literature review, framework development and subsequent building of the measurement tool itself. It also examines feedback on the tool from a panel of global experts and the results of a pilot test conducted in Bauchi and Gombe states in Nigeria. The results demonstrate that the tool is an effective aid for accountability initiatives to reflect on their own progress and provides a useful structure for future planning, monitoring and evaluation. The tool can be applied and adapted to other accountability mechanisms working in global health

A Finite Element Computation of the Gravitational Radiation emitted by a Point-like object orbiting a Non-rotating Black Hole

The description of extreme-mass-ratio binary systems in the inspiral phase is a challenging problem in gravitational wave physics with significant relevance for the space interferometer LISA. The main difficulty lies in the evaluation of the effects of the small body's gravitational field on itself. To that end, an accurate computation of the perturbations produced by the small body with respect the background geometry of the large object, a massive black hole, is required. In this paper we present a new computational approach based on Finite Element Methods to solve the master equations describing perturbations of non-rotating black holes due to an orbiting point-like object. The numerical computations are carried out in the time domain by using evolution algorithms for wave-type equations. We show the accuracy of the method by comparing our calculations with previous results in the literature. Finally, we discuss the relevance of this method for achieving accurate descriptions of extreme-mass-ratio binaries.Comment: RevTeX 4. 18 pages, 8 figure

Evaluating the effects of planning policies on the retail sector: or do town centre first policies deliver the goods

Acknowledgements This paper represents work in progress and is still a preliminary draft. We would like to acknowledge the funding provided to SERC by ESRC, DCLG, BIS and the Welsh Assembly. We have benefited greatly from discussions with many colleagues and professional contacts: we would particularly like to mentio

Interaction effects at the magnetic-field induced metal-insulator transition in Si/SiGe superlattices

A metal-insulator transition was induced by in-plane magnetic fields up to 27 T in homogeneously Sb-doped Si/SiGe superlattice structures. The localisation is not observed for perpendicular magnetic fields. A comparison with magnetoconductivity investigations in the weakly localised regime shows that the delocalising effect originates from the interaction-induced spin-triplet term in the particle-hole diffusion channel. It is expected that this term, possibly together with the singlet particle-particle contribution, is of general importance in disordered n-type Si bulk and heterostructures.Comment: 5 pages, 3 figures, Solid State Communications, in prin

A hysteretic multiscale formulation for nonlinear dynamic analysis of composite materials

This article has been made available through the Brunel Open Access Publishing Fund.A new multiscale finite element formulation is presented for nonlinear dynamic analysis of heterogeneous structures. The proposed multiscale approach utilizes the hysteretic finite element method to model the microstructure. Using the proposed computational scheme, the micro-basis functions, that are used to map the microdisplacement components to the coarse mesh, are only evaluated once and remain constant throughout the analysis procedure. This is accomplished by treating inelasticity at the micro-elemental level through properly defined hysteretic evolution equations. Two types of imposed boundary conditions are considered for the derivation of the multiscale basis functions, namely the linear and periodic boundary conditions. The validity of the proposed formulation as well as its computational efficiency are verified through illustrative numerical experiments

A qualitative understanding of the effects of reusable sanitary pads and puberty education: Implications for future research and practice

BACKGROUND: The management of menstruation has come to the fore as a barrier to girls’ education attainment in low income contexts. Interventions have been proposed and piloted, but the emerging nature of the field means limited evidence is available to understand their pathways of effect. // METHODS: This study describes and compares schoolgirls’ experiences of menstruation in rural Uganda at the conclusion of a controlled trial of puberty education and sanitary pad provision to elucidate pathways of effect in the interventions. Semi-structured interviews were undertaken with schoolgirls who participated in the Menstruation and the Cycle of Poverty trial concurrent with the final set of quantitative surveys. A framework approach and cross-case analysis were employed to describe and compare the experiences of 27 menstruating girls across the four intervention conditions; education (n = 8), reusable sanitary pads (n = 8), education with reusable sanitary pads (n = 6), and control (n = 5). // RESULTS: Themes included: menstrual hygiene, soiling, irritation and infection, physical experience, knowledge of menstruation, psychological, social and cultural factors, and support from others. Those receiving reusable pads experienced improvements in comfort and reliability. This translated into reduced fears around garment soiling and related school absenteeism. Other menstrual hygiene challenges of washing, drying and privacy remained prominent. Puberty education improved girls’ confidence to discuss menstruation and prompted additional support from teachers and peers. // CONCLUSIONS: Findings have important implications for the development and evaluation of future interventions. Results suggest the provision of menstrual absorbents addresses one core barrier to menstrual health, but that interventions addressing broader needs such as privacy may improve effectiveness. Puberty education sessions should increase attention to body awareness and include strategies to address a wider range of practical menstrual challenges, including pain management. Interviews revealed possibilities for improving quantitative surveys in future research

Role of electromagnetically induced transparency in resonant four-wave-mixing schemes.

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