6,702 research outputs found

    On becoming a supervisor: an anticipated transition for trainee clinical psychologists

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    Section A reviews the empirical and theoretical literature on supervision in order to gain a better understanding of how experiences of supervision during clinical training may relate to the anticipated transition of ‘becoming a supervisor’. Section B presents an initial exploratory study focusing on how trainee clinical psychologists make sense of their experiences of supervision in relation to the anticipated transition of ‘becoming a supervisor’. Semi-structured interviews were conducted with ten trainee clinical psychologists at the end of their training. Data was analysed using Interpretative Phenomenological Analysis. Analysis of the transcripts revealed three master themes: the development of the professional self; the supervisory relationship; and the development of supervisory perspectives. Developmental and relational aspects of supervision were emphasised in relation to the anticipated transition of ‘becoming a supervisor’, alongside the significance of the supervisor as a role model. Learning from peers’ experiences of supervision was also key. The study concluded that participants’ experiences of supervision and the meaning they give to those in relation to the anticipated transition of ‘becoming a supervisor’ were connected to the development of a professional self in which increasing autonomy and integration of the personal self was important. Learning took place in the context of the supervisory relationship. The human side of that relationship was valued where reciprocity and containment facilitated a safe space to explore. The development of supervisory perspectives facilitated the anticipated transition of ‘becoming a supervisor’ as experiences of supervision helped to evaluate positive and negative aspects of that role. Subsequently, an ‘ideal for self’ emerged

    Signatures of multiple stellar populations in unresolved extragalactic globular/ young massive star clusters

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    We present an investigation of potential signatures of the formation of multiple stellar populations in recently formed extragalactic star clusters. All of the Galactic globular clusters for which good samples of individual stellar abundances are available show evidence for multiple populations. This appears to require that multiple episodes of star formation and light element enrichment are the norm in the history of a globular cluster. We show that there are detectable observational signatures of multiple formation events in the unresolved spectra of massive, young extragalactic star clusters. We present the results of a pilot program to search for one of the cleanest signatures that we identify - the combined presence of emission lines from a very recently formed population and absorption lines from a somewhat older population. A possible example of such a system is identified in the Antennae galaxies. This source's spectrum shows evidence of two stellar populations with ages of 8 Myr and 80 Myr. Further investigation shows that these populations are in fact physically separated, but only by a projected distance of 59 pc. We show that the clusters are consistent with being bound and discuss the possibility that their coalescence could result in a single globular cluster hosting multiple stellar populations. While not the prototypical system proposed by most theories of the formation of multiple populations in clusters, the detection of this system in a small sample is both encouraging and interesting. Our investigation suggests that expanded surveys of massive young star clusters should detect more clusters with such signatures.Comment: 11 pages, 7 figures: accepted for publication in Ap

    Measuring the cosmological constant with redshift surveys

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    It has been proposed that the cosmological constant Λ\Lambda might be measured from geometric effects on large-scale structure. A positive vacuum density leads to correlation-function contours which are squashed in the radial direction when calculated assuming a matter-dominated model. We show that this effect will be somewhat harder to detect than previous calculations have suggested: the squashing factor is likely to be <1.3<1.3, given realistic constraints on the matter contribution to Ω\Omega. Moreover, the geometrical distortion risks being confused with the redshift-space distortions caused by the peculiar velocities associated with the growth of galaxy clustering. These depend on the density and bias parameters via the combination β≡Ω0.6/b\beta\equiv \Omega^{0.6}/b, and we show that the main practical effect of a geometrical flattening factor FF is to simulate gravitational instability with βeff≃0.5(F−1)\beta_{\rm eff}\simeq 0.5(F-1). Nevertheless, with datasets of sufficient size it is possible to distinguish the two effects; we discuss in detail how this should be done. New-generation redshift surveys of galaxies and quasars are potentially capable of detecting a non-zero vacuum density, if it exists at a cosmologically interesting level.Comment: MNRAS in press. 12 pages LaTeX including Postscript figures. Uses mn.sty and epsf.st

    A Model for Structure Formation Seeded by Gravitationally Produced Matter

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    This model assumes the baryons, radiation, three families of massless neutrinos, and cold dark matter were mutually thermalized before the baryon number was fixed, primeval curvature fluctuations were subdominant, and homogeneity was broken by scale-invariant fluctuations in a new dark matter component that behaves like a relativistic ideal fluid. The fluid behavior could follow if this new component were a single scalar field that interacts only with gravity and with itself by a pure quartic potential. The initial energy distribution could follow if this component were gravitationally produced by inflation. The power spectra of the present distributions of mass and radiation in this model are not inconsistent with the measurements but are sufficiently different from the adiabatic cold dark matter model to allow a sharp test in the near future.Comment: 4 pages, 2 figures submitted to ApJ Letter

    Limits on [OIII] 5007 emission from NGC4472's globular clusters: constraints on planetary nebulae and ultraluminous black hole X-ray binaries in globular clusters

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    We have searched for [OIII] 5007 emission in high resolution spectroscopic data from Flames/Giraffe VLT observations of 174 massive globular clusters (GCs) in NGC4472. No planetary nebulae (PNe) are observed in these clusters, constraining the number of PNe per bolometric luminosity, \alpha<0.8*10^{-7}PN/L_{\odot}. This is significantly lower than the rate predicted from stellar evolution, if all stars produce PNe. Comparing our results to populations of PNe in galaxies, we find most galaxies have a higher \alpha than these GCs (more PNe per bolometric luminosity - though some massive early-type galaxies do have similarly low \alpha). The low \alpha required in these GCs suggests that the number of PNe per bolometric luminosity does not increase strongly with decreasing mass or metallicity of the stellar population. We find no evidence for correlations between the presence of known GC PNe and either the presence of low mass X-ray binaries (LMXBs) or the stellar interaction rates in the GCs. This, and the low \alpha observed, suggests that the formation of PNe may not be enhanced in tight binary systems. These data do identify one [OIII] emission feature, this is the (previously published) broad [OIII] emission from the cluster RZ 2109. This emission is thought to originate from the LMXB in this cluster, which is accreting at super-Eddington rates. The absence of any similar [OIII] emission from the other clusters favors the hypothesis that this source is a black hole LMXB, rather than a neutron star LMXB with significant geometric beaming of its X-ray emission.Comment: 10 pages, 3 figures, accepted for publication in Ap

    Strong lensing time delay: a new way of measuring cosmic shear

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    The phenomenon of cosmic shear, or distortion of images of distant sources unaccompanied by magnification, is an effective way of probing the content and state of the foreground Universe, because light rays do not have to pass through mass structures in order to be sheared. It is shown that the delay in the arrival times between two simultaneously emitted photons that appear to be arriving from a pair of images of a strongly lensed cosmological source contains not only information about the Hubble constant, but also the long range gravitational effect of galactic scale mass clumps located away from the light paths in question. This is therefore also a method of detecting shear. Data on time delays among a sample of strongly lensed sources can provide crucial information about whether extra dynamics beyond gravity and dark energy are responsible for the global flatness of space. If the standard ΛCDM\Lambda CDM model is correct, there should be a large dispersion in the value of H0H_0 as inferred from the delay data by (the usual procedure of) ignoring the effect of all other mass clumps except the strong lens itself. The fact that there has not been any report of a significant deviation from the h=h = 0.7 mark during any of the H0H_0 determinations by this technique may already be pointing to the absence of the random effect discussed here.Comment: ApJ in pres
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