36,788 research outputs found

    The blue one takes a battering why do young adults with asthma overuse bronchodilator inhalers? A qualitative study

    Get PDF
    Objective: Overuse of short-acting bronchodilators is internationally recognised as a marker of poor asthma control, high healthcare use and increased risk of asthma death. Young adults with asthma commonly overuse short-acting bronchodilators. We sought to determine the reasons for overuse of bronchodilator inhalers in a sample of young adults with asthma. Design: Qualitative study using a purposive extreme case sample. Setting: A large urban UK general practice. Participants: Twenty-one adults with moderate asthma, aged 20-32 years. Twelve were high users of short-acting bronchodilators, nine were low users. Results: Asthma had a major impact on respondents' lives, disrupting their childhood, family life and career opportunities. High users of short-acting bronchodilators had adapted poorly to having asthma and expressed anger at the restrictions they experienced. Overuse made sense to them: shortacting bronchodilators were a rapid, effective, cheap 'quick-fix' for asthma symptoms. High users had poorer control of asthma and held explanatory models of asthma which emphasised short-term relief via bronchodilation over prevention. Both high and low users held strong views about having to pay for asthma medication, with costs cited as a reason for not purchasing anti-inflammatory inhalers. Conclusions: Young adults who were high users of short-acting bronchodilators had adapted poorly to having asthma and had poor asthma control. They gave coherent reasons for overuse. Strategies that might address high bronchodilator use in young adults include improving education to help young people accept and adapt to their illness, reducing stigmatisation and providing free asthma medication to encourage the use of anti-inflammatory inhalers

    Faint counts as a function of morphological type in a hierarchical merger model

    Full text link
    The unprecedented resolution of the refurbished Wide Field and Planetary Camera 2 (WFPC2) on the Hubble Space Telescope (HST) has led to major advances in our understanding of galaxy formation. The high image quality in the Medium Deep Survey and Hubble Deep Field has made it possible, for the first time, to classify faint distant galaxies according to morphological type. These observations have revealed a large population of galaxies classed as irregulars or which show signs of recent merger activity. Their abundance rises steeply with apparent magnitude, providing a likely explanation for the large number of blue galaxies seen at faint magnitudes. We demonstrate that such a population arises naturally in a model in which structure forms hierarchically and which is dynamically dominated by cold dark matter. The number counts of irregular, spiral and elliptical galaxies as a function of magnitude seen in the HST data are well reproduced in this model.We present detailed predictions for the outcome of spectroscopic follow-up observations of the HST surveys. By measuring the redshift distributions of faint galaxies of different morphological types, these programmes will provide a test of the hierarchical galaxy formation paradigm and might distinguish between models with different cosmological parameters.Comment: 5 pages, 3 postscript figures included. To be published as a Letter in Monthly Notices of the RAS. Postscript version available at http://star-www.dur.ac.uk/~cmb/counts.htm

    Predictions of entry heating for lower surface of shuttle orbiter

    Get PDF
    A broad base of thermocouple and phase change paint data was assembled and correlated to the nominal design 14414.1 and proposed STS-1 (first flight of the space transportation system) entry trajectories. Averaged data from phase change paint tests compared favorably with thermocouple data for predicting heating rates. Laminar and turbulent radiation equilibrium heating rates were computed on the lower surface of the Shuttle orbiter for both trajectories, and the lower surface center line results were compared both with aerodynamic heating design data and with flight values from the STS-1 and STS-2 trajectories. The peak laminar heating values from the aerodynamic heating design data book were generally 40 to 60 percent higher than the laminar estimates of this study, except at the 55 percent location of maximum span where the design data book values were less than 10 percent higher. Estimates of both laminar and turbulent heating rates compared favorably with flight data

    Distribution of the very first PopIII stars and their relation to bright z~6 quasars

    Full text link
    We discuss the link between dark matter halos hosting the first PopIII stars and the rare, massive, halos that are generally considered to host bright quasars at high redshift z~6. The main question that we intend to answer is whether the super-massive black holes powering these QSOs grew out from the seeds planted by the first intermediate massive black holes created in the universe. This question involves a dynamical range of 10^13 in mass and we address it by combining N-body simulations of structure formation to identify the most massive halos at z~6 with a Monte Carlo method based on linear theory to obtain the location and formation times of the first light halos within the whole simulation box. We show that the descendants of the first ~10^6 Msun virialized halos do not, on average, end up in the most massive halos at z~6, but rather live in a large variety of environments. The oldest PopIII progenitors of the most massive halos at z~6, form instead from density peaks that are on average one and a half standard deviations more common than the first PopIII star formed in the volume occupied by one bright high-z QSO. The intermediate mass black hole seeds planted by the very first PopIII stars at z>40 can easily grow to masses m_BH>10^9.5 Msun by z=6 assuming Eddington accretion with radiative efficiency \epsilon~0.1. Quenching of the black hole accretion is therefore crucial to avoid an overabundance of supermassive black holes at lower redshift. This can be obtained if the mass accretion is limited to a fraction \eta~6*10^{-3} of the total baryon mass of the halo hosting the black hole. The resulting high end slope of the black hole mass function at z=6 is \alpha ~ -3.7, a value within the 1\sigma error bar for the bright end slope of the observed quasar luminosity function at z=6.Comment: 30 pages, 9 figures, ApJ accepte

    Measuring the galaxy power spectrum and scale-scale correlations with multiresolution-decomposed covariance -- I. method

    Get PDF
    We present a method of measuring galaxy power spectrum based on the multiresolution analysis of the discrete wavelet transformation (DWT). Since the DWT representation has strong capability of suppressing the off-diagonal components of the covariance for selfsimilar clustering, the DWT covariance for popular models of the cold dark matter cosmogony generally is diagonal, or jj(scale)-diagonal in the scale range, in which the second scale-scale correlations are weak. In this range, the DWT covariance gives a lossless estimation of the power spectrum, which is equal to the corresponding Fourier power spectrum banded with a logarithmical scaling. In the scale range, in which the scale-scale correlation is significant, the accuracy of a power spectrum detection depends on the scale-scale or band-band correlations. This is, for a precision measurements of the power spectrum, a measurement of the scale-scale or band-band correlations is needed. We show that the DWT covariance can be employed to measuring both the band-power spectrum and second order scale-scale correlation. We also present the DWT algorithm of the binning and Poisson sampling with real observational data. We show that the alias effect appeared in usual binning schemes can exactly be eliminated by the DWT binning. Since Poisson process possesses diagonal covariance in the DWT representation, the Poisson sampling and selection effects on the power spectrum and second order scale-scale correlation detection are suppressed into minimum. Moreover, the effect of the non-Gaussian features of the Poisson sampling can be calculated in this frame.Comment: AAS Latex file, 44 pages, accepted for publication in Ap

    Physical Bias of Galaxies From Large-Scale Hydrodynamic Simulations

    Get PDF
    We analyze a new large-scale (100h−1100h^{-1}Mpc) numerical hydrodynamic simulation of the popular Λ\LambdaCDM cosmological model, including in our treatment dark matter, gas and star-formation, on the basis of standard physical processes. The method, applied with a numerical resolution of <200h−1<200h^{-1}kpc (which is still quite coarse for following individual galaxies, especially in dense regions), attempts to estimate where and when galaxies form. We then compare the smoothed galaxy distribution with the smoothed mass distribution to determine the "bias" defined as b≡(ήM/M)gal/(ήM/M)totalb\equiv (\delta M/M)_{gal}/(\delta M/M)_{total} on scales large compared with the code numerical resolution (on the basis of resolution tests given in the appendix of this paper). We find that (holding all variables constant except the quoted one) bias increases with decreasing scale, with increasing galactic age or metallicity and with increasing redshift of observations. At the 8h−18h^{-1}Mpc fiducial comoving scale bias (for bright regions) is 1.35 at z=0z=0 reaching to 3.6 at z=3z=3, both numbers being consistent with extant observations. We also find that (10−20)h−1(10-20)h^{-1}Mpc voids in the distribution of luminous objects are as observed (i.e., observed voids are not an argument against CDM-like models) and finally that the younger systems should show a colder Hubble flow than do the early type galaxies (a testable proposition). Surprisingly, little evolution is found in the amplitude of the smoothed galaxy-galaxy correlation function (as a function of {\it comoving} separation). Testing this prediction vs observations will allow a comparison between this work and that of Kauffmann et al which is based on a different physical modelingmethod.Comment: in press, ApJ, 26 latex pages plus 7 fig

    Beyond capitalism and liberal democracy: on the relevance of GDH Cole’s sociological critique and alternative

    Get PDF
    This article argues for a return to the social thought of the often ignored early 20th-century English thinker GDH Cole. The authors contend that Cole combined a sociological critique of capitalism and liberal democracy with a well-developed alternative in his work on guild socialism bearing particular relevance to advanced capitalist societies. Both of these, with their focus on the limitations on ‘free communal service’ in associations and the inability of capitalism to yield emancipation in either production or consumption, are relevant to social theorists looking to understand, critique and contribute to the subversion of neoliberalism. Therefore, the authors suggest that Cole’s associational sociology, and the invitation it provides to think of formations beyond capitalism and liberal democracy, is a timely and valuable resource which should be returned to

    Constraints on the Baryonic Compression and Implications for the Fraction of Dark Halo Lenses

    Get PDF
    We predict the fraction of dark halo lenses, that is, the fraction of lens systems produced by the gravitational potential of dark halos, on the basis of a simple parametric model of baryonic compression. The fraction of dark halo lenses primarily contains information on the effect of baryonic compression and the density profile of dark halos, and is expected to be insensitive to cosmological parameters and source population. The model we adopt comprises the galaxy formation probability p_g(M) which describes the global efficiency of baryonic compression and the ratio of circular velocities of galaxies to virial velocities of dark halos gamma_v=v_c/v_{vir} which means how the inner structure of dark halos is modified due to baryonic compression. The model parameters are constrained from the velocity function of galaxies and the distribution of image separations in gravitational lensing, although the degeneracy between model parameters still remains. We show that the fraction of dark halo lenses depends strongly on gamma_v and the density profile of dark halos such as inner slope alpha. This means that the observation of the fraction of dark halos can break the degeneracy between model parameters if the density profile of dark halo lenses is fully settled. On the other hand, by restricting gamma_v to physically plausible range we can predict the lower limit of the fraction of dark halo lenses on the basis of our model. Our result indicates that steeper inner cusps of dark halos (alpha >~ 1.5) or too centrally concentrated dark halos are inconsistent with the lack of dark halo lenses in observations.Comment: 10 pages, 9 figures, emulateapj5, accepted for publication in Ap
    • 

    corecore