Imaginary companions: Clinicians’ observations of their functions and use in therapy with young people referred to CAMHS

Section A provides a critical review of the literature pertinent to children’s imaginary companions, including definitional issues, historical background, and prevalence. Empirical research concerning the characteristics of children who create imaginary companions is presented, followed by an overview of theories attempting to explain the development and functions of imaginary companions. Empirical research investigating the functions of imaginary companions in normative populations is then reviewed, followed by research into the imaginary companions of children from clinical populations. The review concludes by reviewing the literature into the use of imaginary companions as part of psychological therapy. Section B Imaginary companions represent a common childhood developmental phenomenon, to date, largely neglected in the clinical literature. The grounded theory study investigates the functions and therapeutic use of imaginary companions in a clinical population, by interviewing clinicians working therapeutically with young people accessing Child and Adolescent Mental Health Services. Participants were 10 UK clinicians, most practising as child clinical psychologists. Clinicians reported that imaginary companions served a number of fundamental functions, including serving as a communication aide, a secure attachment figure, proving mastery over a child’s world, and acting to maintain stability in the environment, and in a child’s self-image. Imaginary companions were utilised by most clinicians as part of engagement, and to gain insight into young people’s difficulties. Depending on their salience, and congruence with young people’s self-image, imaginary companions were used as therapeutic allies, to aid perspective-taking, and as a way to manage the intensity of interactions with clinicians. Imaginary companions were not therapeutically utilised by a sub-section of clinicians, owing to their perceived low salience, and to clinical risk issues. The findings are discussed in relation to existing theory and research, and methodological limitations, implications for clinical practice, and directions for future research are provided. Section C provides a critical appraisal of the research methodology and findings, and elaborates on clinical implications and future research ideas discussed in Section B

Recent Results from Infrared Observations of White Dwarfs, their Companions, and the Dust that Surrounds Them

Although "traditionally" observed at short wavelengths, white dwarfs have displayed many surprising features when probed in the infrared. We present an overview of recent results from ground- and space-based near- to mid-infrared observations of white dwarfs. These include the discovery of many new candidate binary stars containing low mass stellar or sub-stellar companions from a sample of objects previously thought to be single white dwarfs, and Spitzer Space Telescope observations that suggest that dust is common in the environs of white dwarfs in cataclysmic variables

SGR J1550–5418 Bursts Detected with the Fermi Gamma-Ray Burst Monitor during its Most Prolific Activity

We have performed detailed temporal and time-integrated spectral analysis of 286 bursts from SGR J1550–5418 detected with the Fermi Gamma-ray Burst Monitor (GBM) in 2009 January, resulting in the largest uniform sample of temporal and spectral properties of SGR J1550–5418 bursts. We have used the combination of broadband and high time-resolution data provided with GBM to perform statistical studies for the source properties. We determine the durations, emission times, duty cycles, and rise times for all bursts, and find that they are typical of SGR bursts. We explore various models in our spectral analysis, and conclude that the spectra of SGR J1550–5418 bursts in the 8-200 keV band are equally well described by optically thin thermal bremsstrahlung (OTTB), a power law (PL) with an exponential cutoff (Comptonized model), and two blackbody (BB) functions (BB+BB). In the spectral fits with the Comptonized model, we find a mean PL index of –0.92, close to the OTTB index of –1. We show that there is an anti-correlation between the Comptonized E_(peak) and the burst fluence and average flux. For the BB+BB fits, we find that the fluences and emission areas of the two BB functions are correlated. The low-temperature BB has an emission area comparable to the neutron star surface area, independent of the temperature, while the high-temperature BB has a much smaller area and shows an anti-correlation between emission area and temperature. We compare the properties of these bursts with bursts observed from other SGR sources during extreme activations, and discuss the implications of our results in the context of magnetar burst models

White Dwarf - Red Dwarf Systems Resolved with the Hubble Space Telescope. II. Full Snapshot Survey Results

Results are presented for a Hubble Space Telescope Advanced Camera for Surveys high-resolution imaging campaign of 90 white dwarfs with known or suspected low mass stellar and substellar companions. Of the 72 targets which remain candidate and confirmed white dwarfs with near-infrared excess, 43 are spatially resolved into two or more components, and a total of 12 systems are potentially triples. There is a possible, slight deficit of earlier spectral types (bluer colors) among the spatially unresolved companions, exactly the opposite of expectations if significant mass is transferred to the companion during the common envelope phase. Using the best available distance estimates, the low mass companions to white dwarfs exhibit a bimodal distribution in projected separation. This result supports the hypothesis that during the giant phases of the white dwarf progenitor, any unevolved companions either migrate inward to short periods of hours to days, or outward to periods of hundreds to thousands of years. No intermediate projected separations of a few to several AU are found among these pairs. However, a few double M dwarfs (within triples) are spatially resolved in this range, empirically demonstrating that such separations were readily detectable among the binaries with white dwarfs. A straightforward and testable prediction emerges: all spatially unresolved, low mass stellar and substellar companions to white dwarfs should be in short period orbits. This result has implications for substellar companion and planetary orbital evolution during the post-main sequence lifetime of their stellar hosts.Comment: Accepted to ApJ Supplement Series, emulateapj format, 14 figures, 8 table

On the Complexity of the Equivalence Problem for Probabilistic Automata

Checking two probabilistic automata for equivalence has been shown to be a key problem for efficiently establishing various behavioural and anonymity properties of probabilistic systems. In recent experiments a randomised equivalence test based on polynomial identity testing outperformed deterministic algorithms. In this paper we show that polynomial identity testing yields efficient algorithms for various generalisations of the equivalence problem. First, we provide a randomized NC procedure that also outputs a counterexample trace in case of inequivalence. Second, we show how to check for equivalence two probabilistic automata with (cumulative) rewards. Our algorithm runs in deterministic polynomial time, if the number of reward counters is fixed. Finally we show that the equivalence problem for probabilistic visibly pushdown automata is logspace equivalent to the Arithmetic Circuit Identity Testing problem, which is to decide whether a polynomial represented by an arithmetic circuit is identically zero.Comment: technical report for a FoSSaCS'12 pape