23,448 research outputs found

    Turning the Big Mac Index into the Medical MAC Index

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    Objective: The purpose of this study was to create a global medical earnings index, called the Medical MAC Index, to enable a comparison of what medical specialists earn in the countries included in the study.Design: The study gathered data on the earnings of specialist anaesthetists employed in state hospitals with five years’ work experience, across 49 developed and developing countries.Setting and subjects: The earnings of anaesthetists were deemed to be indicative of all medical specialities because anaesthesia is one of the largest specialities, and most state hospitals do not distinguish between medical specialities from an earnings perspective. It is likely that a specialist with five years’ work experience would have reached the higher echelons of state salary scales, but it is unlikely that he or she would have moved into a management role yet.Outcome measures: To calculate a Medical MAC Index for a specific country, the net earnings of anaesthetists in the countries included in the study were converted into USA dollars, and adjusted using Xpatulator’s purchasing power parity model, and then compared to the net earnings of an anaesthetist in that specific country. The specific country was the baseline. Countries above the line pay more, and those below the line, less.Results: The Medical MAC Index for South Africa showed that medical specialists employed by the state in South Africa earn more than they would in most developing countries, but their earnings lag behind those of many developed countries.Conclusion: South Africa could become more competitive if tax incentives were used to manipulate the data

    Acoustic suppression of the coffee-ring effect

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    We study the influence of acoustic fields on the evaporative self-assembly of solute particles suspended inside sessile droplets of complex fluids. The self-assembly process often results in an undesirable ring-like heterogeneous residue, a phenomenon known as the coffee-ring effect. Here we show that this ring-like self-assembly can be controlled acoustically to form homogeneous disc-like or concentrated spot-like residues. The principle of our method lies in the formation of dynamic patterns of particles in acoustically excited droplets, which inhibits the evaporation-driven convective transport of particles towards the contact line. We elucidate the mechanisms of this pattern formation and also obtain conditions for the suppression of the coffee-ring effect. Our results provide a more general solution to suppress the coffee-ring effect without any physiochemical modification of the fluids, the particles or the surface, thus potentially useful in a broad range of industrial and analytical applications that require homogenous solute depositions

    Simplicial gauge theory on spacetime

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    We define a discrete gauge-invariant Yang-Mills-Higgs action on spacetime simplicial meshes. The formulation is a generalization of classical lattice gauge theory, and we prove consistency of the action in the sense of approximation theory. In addition, we perform numerical tests of convergence towards exact continuum results for several choices of gauge fields in pure gauge theory.Comment: 18 pages, 2 figure

    Measuring intestinal fluid transport in vitro: Gravimetric method versus non-absorbable marker

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    This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.The gut sac is a long-standing, widely used in vitro preparation for studying solute and water transport, and calculation of these fluxes requires an accurate assessment of volume. This is commonly determined gravimetrically by measuring the change in mass over time. While convenient this likely under-estimates actual net water flux (Jv) due to tissue edema. We evaluated whether the popular in vivo volume marker [(14)C]-PEG 4000, offers a more representative measure of Jvin vitro. We directly compared these two methods in five teleost species (toadfish, flounder, rainbow trout, killifish and tilapia). Net fluid absorption by the toadfish intestine based on PEG was significantly higher, by almost 4-fold, compared to gravimetric measurements, compatible with the latter under-estimating Jv. Despite this, PEG proved inconsistent for all of the other species frequently resulting in calculation of net secretion, in contrast to absorption seen gravimetrically. Such poor parallelism could not be explained by the absorption of [(14)C]-PEG (typically <1%). We identified a number of factors impacting the effectiveness of PEG. One was adsorption to the surface of sample tubes. While it was possible to circumvent this using unlabelled PEG 4000, this had a deleterious effect on PEG-based Jv. We also found sequestration of PEG within the intestinal mucus. In conclusion, the short-comings associated with the accurate representation of Jv by gut sac preparations are not overcome by [(14)C]-PEG. The gravimetric method therefore remains the most reliable measure of Jv and we urge caution in the use of PEG as a volume marker.We are grateful to Ian and Tony McClure, the local fishermen of Flookburgh, Cumbria (U.K.) for collecting the flounder used in this study, and to Jan Shears for assistance with fish husbandry at Exeter (U.K.). We thank Ray Hurley and Debbie Fretz in Miami (U.S.A.) for supplying the toadfish. This work was supported by the Biotechnology and Biological Sciences Research Council (BBSRC) grants BBS/S/A/2004/11078 and BB/F009364/1 to R.W.W., and National Science Foundation (NSF) grants IAB0743903 and 1146695 to M.G

    Optimizing the Performance of Aerosol Photoacoustic Cells using a Finite Element Model. Part 2: Application to a Two-Resonator Cell

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    This is the author accepted manuscript. The final version is available from Taylor & Francis via the DOI in this recordData availability: For data related to this paper, please contact Michael I. Cotterell ([email protected]).Photoacoustic spectroscopy (PAS) measures aerosol absorption in a non-contact manner, providing accurate absorption measurements that are needed to improve aerosol optical property representations in climate models. Central to PAS is resonant amplification of the acoustic pressure wave generated from laser-heated aerosol transferring heat to surrounding gas by a photoacoustic cell. Although this cell amplifies pressure sources from aerosol absorption (signal), it also amplifies noise and background sources. It is important to maximise the cell signal-to-background ratio (SBR) for sensitive absorption measurements. Many researchers have adopted the two-resonator cell design described by Lack et al. (2006). We show that the uncertainty in PAS measurements of aerosol absorption using this two-resonator cell is significantly degraded by its large sensitivity to background contributions from laser scattering and absorption at the cell windows. In Part 1, we described the use of a finite element method (FEM) to predict cell acoustic properties, validated this framework by comparing model predictions to measurements, and used FEM to test various strategies applied commonly to single-resonator cell optimisation. In this second part, we apply FEM to understand the excitation of resonant modes of the two-resonator cell, with comparison measurements demonstrating accurate predictions of acoustic response. We perform geometry optimisation studies to maximise the SBR and demonstrate that the laser-window interaction background is reduced to undetectable levels for an optimal cell. This optimised two-resonator cell will improve the sensitivity and accuracy of future aerosol absorption measurements.Defence Science and Technology Laboratory (DSTL)Royal Society of ChemistryAnalytical Chemistry Trust FundNatural Environment Research Council (NERC

    Development of G: A test in an amphibious fish

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    This is the author accepted manuscript. The final version is available from Springer Nature via the DOI in this record.The data used in this manuscript has been achieved in Dryad repository: doi:10.5061/dryad.m56pj5b.Heritable variation in, and genetic correlations among, traits determine the response of multivariate phenotypes to natural selection. However, as traits develop over ontogeny, patterns of genetic (co)variation and integration captured by the G matrix may also change. Despite this, few studies have investigated how genetic parameters underpinning multivariate phenotypes change as animals pass through major life history stages. Here, using a self-fertilizing hermaphroditic fish species, mangrove rivulus (Kryptolebias marmoratus), we test the hypothesis that G changes from hatching through reproductive maturation. We also test Cheverud’s conjecture by asking whether phenotypic patterns provide an acceptable surrogate for patterns of genetic (co)variation within and across ontogenetic stages. For a set of morphological traits linked to locomotor (jumping) performance, we find that the overall level of genetic integration (as measured by the mean-squared correlation across all traits) does not change significantly over ontogeny. However, we also find evidence that some trait-specific genetic variances and pairwise genetic correlations do change. Ontogenetic changes in G indicate the presence of genetic variance for developmental processes themselves, while also suggesting that any genetic constraints on morphological evolution may be age-dependent. Phenotypic correlations closely resembled genetic correlations at each stage in ontogeny. Thus, our results are consistent with the premise that – at least under common environment conditions - phenotypic correlations can be a good substitute for genetic correlations in studies of multivariate developmental evolution

    The role of reinvestment in performance of simulated laparoscopic surgery under time pressure

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    Free Communications: Verbal and Poster - Motor Learning and ControlOBJECTIVE: To examine the impact of ‘reinvestment’ on laparoscopic performance under a common intra-operative stressor, time pressure. Background Study of the breakdown of performance under stress has been gaining momentum in the motor skill learning domain as well as domains like aviation and anesthesia, but this has not been the case in the domain of surgery until recently. Research on intra-operative stressors has focused on external factors without considering individual differences in the ability to cope with stress. One individual difference that is implicated in adverse effects of stress on performance is ‘reinvestment’, the propensity for conscious monitoring and control of movements. METHODS: Thirty-one medical students were divided into high and low reinvestment groups based on their scores on the Movement Specific Reinvestment Scale. Participants were first trained to proficiency on a peg transfer task and then tested on the same task in a control and time pressure condition. In the control condition, participants were simply asked to do their best, as they had in training. In the time pressure condition, participants were informed that operating surgeons sometimes are required to perform under time constraints and they should try to complete the task faster than their best time in training (of which they were informed).Outcome measures included generic performance and process measures. Stress levels were assessed using heart rate and the State Trait Anxiety Inventory (STAI). RESULTS: High and low reinvesters demonstrated increased anxiety levels from control to time pressure conditions as indicated by their STAI scores, although no differences in heart rate were found. Low reinvesters performed significantly faster when under time pressure, whereas high reinvesters showed no change in performance times. Low reinvesters tended to display greater performance efficiency (shorter path lengths, fewer hand movements) than high reinvesters. Conclusion Trained medical students with a high individual propensity to consciously monitor and control their movements (high reinvesters) displayed less capability (than low reinvesters) to meet the demands imposed by time pressure during a laparoscopic task. The finding implies that the propensity for reinvestment may have a moderating effect on laparoscopic performance under time pressure.published_or_final_versionThe 2012 Conference of the North American Society for the Psychology of Sport and Physical Activity (NASPSPA 2012), Honolulu, HI., 7-9 June 2012. In Journal of Sport and Exercise Psychology, 2012, v. 34 suppl., p. S10

    Examining Movement-Specific Reinvestment and Performance in Demanding Contexts.

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    Two experiments examined the roles of the dimensions of movement-specific reinvestment (movement self-consciousness and conscious motor processing) on performance under demanding conditions. In Experiment 1, novice golfers practiced a golf putting task and were tested under low- and high-anxiety conditions. Conscious motor processing was not associated with putting proficiency or movement variability; however, movement self-consciousness was positively associated with putting proficiency and appeared to be negatively associated with variability of impact velocity in low-anxiety conditions, but not in high-anxiety conditions. Increased anxiety and effort possibly left few attention resources for movement self-consciousness under high anxiety. In Experiment 2, participants performed a quiet standing task in single- and dual-task conditions. Movement self-consciousness was positively associated with performance when attention demands were low (single task) but not when attention demands were high (dual task). The findings provide insight into the differential influence of the two dimensions of movement-specific reinvestment under demanding conditions
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