6,968 research outputs found

    Modelling the evaporation of nanoparticle suspensions from heterogeneous surfaces

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    We present a Monte Carlo (MC) grid-based model for the drying of drops of a nanoparticle suspension upon a heterogeneous surface. The model consists of a generalised lattice-gas in which the interaction parameters in the Hamiltonian can be varied to model different properties of the materials involved. We show how to choose correctly the interactions, to minimise the effects of the underlying grid so that hemispherical droplets form. We also include the effects of surface roughness to examine the effects of contact-line pinning on the dynamics. When there is a `lid' above the system, which prevents evaporation, equilibrium drops form on the surface, which we use to determine the contact angle and how it varies as the parameters of the model are changed. This enables us to relate the interaction parameters to the materials used in applications. The model has also been applied to drying on heterogeneous surfaces, in particular to the case where the suspension is deposited on a surface consisting of a pair of hydrophilic conducting metal surfaces that are either side of a band of hydrophobic insulating polymer. This situation occurs when using inkjet printing to manufacture electrical connections between the metallic parts of the surface. The process is not always without problems, since the liquid can dewet from the hydrophobic part of the surface, breaking the bridge before the drying process is complete. The MC model reproduces the observed dewetting, allowing the parameters to be varied so that the conditions for the best connection can be established. We show that if the hydrophobic portion of the surface is located at a step below the height of the neighbouring metal, the chance of dewetting of the liquid during the drying process is significantly reduced.Comment: 14 pages, 14 figure

    Aspirated capacitor measurements of air conductivity and ion mobility spectra

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    Measurements of ions in atmospheric air are used to investigate atmospheric electricity and particulate pollution. Commonly studied ion parameters are (1) air conductivity, related to the total ion number concentration, and (2) the ion mobility spectrum, which varies with atmospheric composition. The physical principles of air ion instrumentation are long-established. A recent development is the computerised aspirated capacitor, which measures ions from (a) the current of charged particles at a sensing electrode, and (b) the rate of charge exchange with an electrode at a known initial potential, relaxing to a lower potential. As the voltage decays, only ions of higher and higher mobility are collected by the central electrode and contribute to the further decay of the voltage. This enables extension of the classical theory to calculate ion mobility spectra by inverting voltage decay time series. In indoor air, ion mobility spectra determined from both the novel voltage decay inversion, and an established voltage switching technique, were compared and shown to be of similar shape. Air conductivities calculated by integration were: 5.3 +- 2.5 fS/m and 2.7 +- 1.1 fS/m respectively, with conductivity determined to be 3 fS/m by direct measurement at a constant voltage. Applications of the new Relaxation Potential Inversion Method (RPIM) include air ion mobility spectrum retrieval from historical data, and computation of ion mobility spectra in planetary atmospheres.Comment: To be published in Review of Scientific Instrument

    VisGenome: visualization of single and comparative genome representations

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    VisGenome visualizes single and comparative representations for the rat, the mouse and the human chromosomes at different levels of detail. The tool offers smooth zooming and panning which is more flexible than seen in other browsers. It presents information available in Ensembl for single chromosomes, as well as homologies (orthologue predictions including ortholog one2one, apparent ortholog one2one, ortholog many2many) for any two chromosomes from different species. The application can query supporting data from Ensembl by invoking a link in a browser

    Is the Scottish population living dangerously? Prevalence of multiple risk factors: the Scottish Health Survey 2003

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    <b>Background:</b> Risk factors are often considered individually, we aimed to investigate the prevalence of combinations of multiple behavioural risk factors and their association with socioeconomic determinants.<p></p> <b>Methods:</b> Multinomial logistic regression was used to model the associations between socioeconomic factors and multiple risk factors from data in the Scottish Health Survey 2003. Prevalence of five main behavioural risk factors - smoking alcohol, diet, overweight/obesity, and physical inactivity, and the odds in relation to demographic, individual and area socioeconomic factors.<p></p> <b>Results:</b> Full data were available on 6,574 subjects (80.7% of the survey sample). Nearly the whole adult population (97.5%) reported to have at least one behavioural risk factor; while 55% have three or more risk factors; and nearly 20% have four or all five risk factors. The most important determinants for having four or five multiple risk factors were low educational attainment which conferred around a 3-fold increased odds compared to high education; and residence in the most deprived communities (relative to least deprived) which had greater than 3-fold increased odds.<p></p> <b>Conclusions:</b> The prevalence of multiple behavioural risk factors was high and the prevalence of absence of all risk factors very low. These behavioural patterns were socioeconomically determined. Policy to address factors needs to be joined up and better consider underlying socioeconomic circumstances.<p></p&gt

    The Intermediate Coupling Regime in the AdS/CFT Correspondence

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    The correspondence between the 't Hooft limit of N=4 super Yang-Mills theory and tree-level IIB superstring theory on AdS(5)xS(5) in a Ramond-Ramond background at values of lambda=g^2 N ranging from infinity to zero is examined in the context of unitarity. A squaring relation for the imaginary part of the holographic scattering of identical string fields in the two-particle channels is found, and a mismatch between weak and strong 't Hooft coupling is pointed out within the correspondence. Several interpretations and implications are proposed.Comment: 10 pages, LaTeX, reference adde

    National survey of the prevalence, incidence, primary care burden, and treatment of heart failure in Scotland

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    Objective: To examine the epidemiology, primary care burden, and treatment of heart failure in Scotland, UK. Design: Cross sectional data from primary care practices participating in the Scottish continuous morbidity recording scheme between 1 April 1999 and 31 March 2000. Setting: 53 primary care practices (307 741 patients). Subjects: 2186 adult patients with heart failure. Results: The prevalence of heart failure in Scotland was 7.1 in 1000, increasing with age to 90.1 in 1000 among patients 85 years. The incidence of heart failure was 2.0 in 1000, increasing with age to 22.4 in 1000 among patients 85 years. For older patients, consultation rates for heart failure equalled or exceeded those for angina and hypertension. Respiratory tract infection was the most common co-morbidity leading to consultation. Among men, 23% were prescribed a ß blocker, 11% spironolactone, and 46% an angiotensin converting enzyme inhibitor. The corresponding figures for women were 20% (p = 0.29 versus men), 7% (p = 0.02), and 34% (p < 0.001). Among patients < 75 years 26% were prescribed a β blocker, 11% spironolactone, and 50% an angiotensin converting enzyme inhibitor. The corresponding figures for patients 75 years were 19% (p = 0.04 versus patients < 75), 7% (p = 0.04), and 33% (p < 0.001). Conclusions: Heart failure is a common condition, especially with advancing age. In the elderly, the community burden of heart failure is at least as great as that of angina or hypertension. The high rate of concomitant respiratory tract infection emphasises the need for strategies to immunise patients with heart failure against influenza and pneumococcal infection. Drugs proven to improve survival in heart failure are used less frequently for elderly patients and women

    Exact low-energy effective actions for hypermultiplets in four dimensions

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    We consider the general hypermultiplet Low-Energy Effective Action (LEEA) that may appear in quantized, four-dimensional, N=2 supersymmetric, gauge theories, e.g. in the Coulomb and Higgs branches. Our main purpose is a description of the exact LEEA of n magnetically charged hypermultiplets. The hypermultiplet LEEA is given by the N=2 supersymmetric Non-Linear Sigma-Model (NLSM) with a 4n-dimensional hyper-K"ahler metric, subject to non-anomalous symmetries. Harmonic Superspace (HSS) and the NLSM isometries are very useful to constrain the hyper-K"ahler geometry of the LEEA. We use N=2 supersymmetric projections of HSS superfields to N=2 linear (tensor) O(2) and O(4) multiplets in N=2 Projective Superspace (PSS) to deduce the explicit form of the LEEA in some particular cases. As the by-product, a simple new classification of all multi-monopole moduli space metrics having su(2)_R symmetry is proposed in terms of real quartic polynomials of 2n variables, modulo Sp(n) transformations. The 4d hypermultiplet LEEA for n=2 can be encoded in terms of an elliptic curve.Comment: 60 pages, LaTeX, macros included, references adde

    Bronchiectasis insanity:Doing the same thing over and over again and expecting different results?

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    Bronchiectasis is an increasingly common disease with a significant impact on quality of life and morbidity of affected patients. It is also a very heterogeneous disease with numerous different underlying etiologies and presentations. Most treatments for bronchiectasis are based on low-quality evidence; consequently, no treatments have been approved by the US Food and Drug Administration or the European Medicines Agency for the treatment of bronchiectasis. The last several years have seen numerous clinical trials in which the investigational agent, thought to hold great promise, did not demonstrate a clinically or statistically significant benefit. This commentary will review the likely reasons for these disappointing results and a potential approach that may have a greater likelihood of defining evidence-based treatment for bronchiectasis

    Simplifying Algebra in Feynman Graphs, Part III: Massive Vectors

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    A T-dualized selfdual inspired formulation of massive vector fields coupled to arbitrary matter is generated; subsequently its perturbative series modeling a spontaneously broken gauge theory is analyzed. The new Feynman rules and external line factors are chirally minimized in the sense that only one type of spin index occurs in the rules. Several processes are examined in detail and the cross-sections formulated in this approach. A double line formulation of the Lorentz algebra for Feynman diagrams is produced in this formalism, similar to color ordering, which follows from a spin ordering of the Feynman rules. The new double line formalism leads to further minimization of gauge invariant scattering in perturbation theory. The dualized electroweak model is also generated.Comment: 39 pages, LaTeX, 8 figure
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