GP prescribing of nicotine replacement and bupropion to aid smoking cessation in England and Wales

Aims Prescribing nicotine replacement therapy (NRT) or bupropion for smoking cessation is of considerable importance to public health but little is known about prescribing practices. This paper examines general practitioners' (GPs') prescribing patterns in Britain where these drugs are reimbursed. The results have implications for other health-care systems considering introducing reimbursement.Design, participants and setting Postal survey conducted in 2002 of a random sample of 1088 GPs in England and Wales, of whom 642 (59%) responded.Measures Number of requests GPs reported having received from patients for NRT and bupropion over the past month, the number of prescriptions they reported issuing and ratings of attitudes to these medications.Findings GPs reported receiving an average of 4.3 requests for NRT and 1.9 for bupropion in the previous month. They reported issuing 3.5 prescriptions for NRT and 1.2 for bupropion. Almost all GPs accepted that NRT (95%) and bupropion (97%) should be reimbursable on National Health Service (NHS) prescription. However, a significant minority of those who received requests for prescriptions did not issue any (81% for NRT and 26% for bupropion). This was related to whether they thought these products should be available on NHS prescription for both NRT and bupropion (OR = 0.66, P < 0.05), which in turn was related to beliefs about whether smokers should have to pay for treatment themselves, the cost-effectiveness of NRT/bupropion and the low priority they would give NRT/bupropion in the drug budget. For bupropion, concern about side-effects independently predicted not prescribing [odds ratio (OR) = 1.46, P < 0.03].Conclusion In the British health-care system, which has a well-established system for technology assessment and professionally endorsed guidelines, a significant minority of GPs decline all patient requests for stop-smoking medicines

Small linear wind tunnel saltation experiments: Some experiences

Since the wind tunnels proposed to be used for the Space Station Planetology Experiments are of a rather limited size, some experience and techniques used for saltation experiments in a small linear wind tunnel may be of interest. Three experiments will be presented. The first concerns a length effect of saltation mass flux in which the size of the wind tunnel exaggerates the physical process taking place. The second experiment concerns a nonoptical technique that does not interfere with flow and by which momentum flux to the floor may be measured. The technique may also be used to calculate saltation flux (using appropriate assumptions). The third experiment concerns the use of the momentum equation to estimate momentum fluxes by difference

Analysis of a Helmholtz preconditioning problem motivated by uncertainty quantification

This paper analyses the following question: let $\mathbf{A}_j$, $j=1,2,$ be the Galerkin matrices corresponding to finite-element discretisations of the exterior Dirichlet problem for the heterogeneous Helmholtz equations $\nabla\cdot (A_j \nabla u_j) + k^2 n_j u_j= -f$. How small must $\|A_1 -A_2\|_{L^q}$ and $\|{n_1} - {n_2}\|_{L^q}$ be (in terms of $k$-dependence) for GMRES applied to either $(\mathbf{A}_1)^{-1}\mathbf{A}_2$ or $\mathbf{A}_2(\mathbf{A}_1)^{-1}$ to converge in a $k$-independent number of iterations for arbitrarily large $k$? (In other words, for $\mathbf{A}_1$ to be a good left- or right-preconditioner for $\mathbf{A}_2$?). We prove results answering this question, give theoretical evidence for their sharpness, and give numerical experiments supporting the estimates. Our motivation for tackling this question comes from calculating quantities of interest for the Helmholtz equation with random coefficients $A$ and $n$. Such a calculation may require the solution of many deterministic Helmholtz problems, each with different $A$ and $n$, and the answer to the question above dictates to what extent a previously-calculated inverse of one of the Galerkin matrices can be used as a preconditioner for other Galerkin matrices

Universal thermodynamic bounds on nonequilibrium response with biochemical applications

Diverse physical systems are characterized by their response to small perturbations. Near thermodynamic equilibrium, the fluctuation-dissipation theorem provides a powerful theoretical and experimental tool to determine the nature of response by observing spontaneous equilibrium fluctuations. In this spirit, we derive here a collection of equalities and inequalities valid arbitrarily far from equilibrium that constrain the response of nonequilibrium steady states in terms of the strength of nonequilibrium driving. Our work opens new avenues for characterizing nonequilibrium response. As illustrations, we show how our results rationalize the energetic requirements of two common biochemical motifs.Comment: 21 pages, 15 figure

Measurement of long-range steric repulsions between microspheres due to an adsorbed polymer

We have measured the interparticle potential between pairs of micron-sized silica spheres induced by adsorbed polyethylene oxide polymer using a line-scanned optical tweezer. We found this long-range steric repulsion to be exponential over the range of energies (0.1kBT–5kBT) and polymer molecular weights (452 000–1 580 000) studied, and that the potential scaled with the polymer’s radius of gyration RG. The potential’s exponential decay length was about 0.6RG and its range was about 4RG, although both parameters varied significantly from one pair of spheres to another. The potential’s exponential prefactor was greater than mean-field predictions

Ion-tracer anemometer

Gas velocity measuring instrument measures transport time of ion-trace traveling fixed distance between ionization probe and detector probe. Electric field superimposes drift velocity onto flow velocity so travel times can be reduced to minimize ion diffusion effects

Performance of a tandem-rotor/tandem-stator conical-flow compressor designed for a pressure ratio of 3

A conical-flow compressor stage with a large radius change through the rotor was tested at three values of rotor tip clearance. The stage had a tandem rotor and a tandem stator. Peak efficiency at design speed was 0.774 at a pressure ratio of 2.613. The rotor was tested without the stator, and detailed survey data were obtained for each rotor blade row. Overall peak rotor efficiency was 0.871 at a pressure ratio of 2.952