2,724 research outputs found

    'The world is full of big bad wolves': investigating the experimental therapeutic spaces of R.D. Laing and Aaron Esterson

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    In conjunction with the recent critical assessments of the life and work of R.D. Laing, this paper seeks to demonstrate what is revealed when Laing’s work on families and created spaces of mental health care are examined through a geographical lens. The paper begins with an exploration of Laing’s time at the Tavistock Clinic in London during the 1960s, and of the co-authored text with Aaron Esterson entitled, Sanity, Madness and the Family (1964). The study then seeks to demonstrate the importance Laing and his colleague placed on the time-space situatedness of patients and their worlds. Finally, an account is provided of Laing’s and Esterson’s spatial thinking in relation to their creation of both real and imagined spaces of therapeutic care

    Analysing the Transverse Structure of the Relativistic Jets of AGN

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    This paper describes a method of fitting total intensity and polarization profiles in VLBI images of astrophysical jets to profiles predicted by a theoretical model. As an example, the method is used to fit profiles of the jet in the Active Galactic Nucleus Mrk501 with profiles predicted by a model in which a cylindrical jet of synchrotron plasma is threaded by a magnetic field with helical and disordered components. This fitting yields model Stokes Q profiles that agree with the observed profiles to within the 1-2 \sigma uncertainties; the I model and observed profiles are overall not in such good agreement, with the model I profiles being generally more symmetrical than the observed profiles. Consistent fitting results are obtained for profiles derived from 6cm VLBI images at two distances from the core, and also for profiles obtained for different wavelengths at a single location in the VLBI jet. The most striking success of the model is its ability to reproduce the spine-sheath polarization structure observed across the jet. Using the derived viewing angle in the jet rest frame, \delta' approximately 83 degrees, together with a superluminal speed reported in the literature, \beta apparent = 3.3, yields a solution for the viewing angle and velocity of the jet in the observer's frame \delta degrees and \beta approximately 0.96. Although these results for Mrk501 must be considered tentative, the combined analysis of polarization profiles and apparent component speeds holds promise as a means of further elucidating the magnetic field structures and other parameters of parsec-scale AGN jets

    The IRAS Revised Bright Galaxy Sample (RBGS)

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    IRAS flux densities, redshifts, and infrared luminosities are reported for all sources identified in the IRAS Revised Bright Galaxy Sample (RBGS), a complete flux-limited survey of all extragalactic objects with total 60 micron flux density greater than 5.24 Jy, covering the entire sky surveyed by IRAS at Galactic latitude |b| > 5 degrees. The RBGS includes 629 objects, with a median (mean) sample redshift of 0.0082 (0.0126) and a maximum redshift of 0.0876. The RBGS supersedes the previous two-part IRAS Bright Galaxy Samples, which were compiled before the final ("Pass 3") calibration of the IRAS Level 1 Archive in May 1990. The RBGS also makes use of more accurate and consistent automated methods to measure the flux of objects with extended emission. Basic properties of the RBGS sources are summarized, including estimated total infrared luminosities, as well as updates to cross-identifications with sources from optical galaxy catalogs established using the NASA/IPAC Extragalactic Database (NED). In addition, an atlas of images from the Digitized Sky Survey with overlays of the IRAS position uncertainty ellipse and annotated scale bars is provided for ease in visualizing the optical morphology in context with the angular and metric size of each object. The revised bolometric infrared luminosity function, phi(L_ir), for infrared bright galaxies in the local Universe remains best fit by a double power law, phi(L_ir) ~ L_ir^alpha, with alpha = -0.6 (+/- 0.1), and alpha = -2.2 (+/- 0.1) below and above the "characteristic" infrared luminosity L_ir ~ 10^{10.5} L_solar, respectively. (Abridged)Comment: Accepted for publication in the Astronomical Journal. Contains 50 pages, 7 tables, 16 figures. Due to astro-ph space limits, only 1 of 26 pages of Figure 1, and 1 of 11 pages of Table 7, are included; full resolution Postscript files are available at http://nedwww.ipac.caltech.edu/level5/March03/IRAS_RBGS/Figures/ . Replacement: Corrected insertion of Fig. 15 (MethodCodes.ps) in LaTe

    Relativistic Landau damping of longitudinal waves in isotropic pair plasmas

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    Landau damping is described in relativistic electron-positron plasmas. Relativistic electron-positron plasma theory contains important new effects when compared with classical plasmas. For example, there are undamped superluminal wave modes arising from both a continuous and discrete mode structure, the former even in the classical limit. We present here a comprehensive analytical treatment of the general case resulting in a compact and useful form for the dispersion relation. The classical pair-plasma case is addressed, for completeness, in an appendix

    Factors affecting metal mobilisation during oxidation of sulphidic, sandy wetland substrates

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    Most metals accumulate as sulphides under anoxic conditions in wetland substrates, reducing their bioavailability due to the solubility of metal sulphides. However, upon oxidation of these sulphides when the substrate is occasionally oxidised, metals can be released from the solid phase to the pore water or overlaying surface water. This release can be affected by the presence of carbonates, organic matter and clay. We compared changes of Cd, Cu and Zn mobility (CaCl2 extraction) during oxidation of a carbonate-rich and a carbonate-poor sulphidic, sandy wetland substrate. In addition, we studied how clay with low and high cation sorption capacity (bentonite and kaolinite, respectively) and organic matter (peat) can counteract Cd, Cu and Zn release during oxidation of both carbonate-rich and carbonate-poor sulphidic sediments. CaCl2-extractability of Cu, a measure for its availability, is low in both carbonate-poor and carbonate-rich substrates, whereas its variability is high. The availability of Cd and Zn is much higher and increases when peat is supplied to carbonate-poor substrates. A strong reduction of Cd and Zn extractability is observed when clay is added to carbonate-poor substrates. This reduction depends on the clay type. Most observations could be explained taking into account pH differences between treatments, with kaolinite resulting in a lower pH in comparison to bentonite. These pH differences affect the presence and characteristics of dissolved organic carbon and the metal speciation, which in turns affects the interaction of metals with the solid soil phase. In carbonate-rich substrates, Cd and Zn availability is lower and the effects of peat and clay amendment are less clear. The latter can also be attributed to the high pH and lack of pH differences between treatments

    Direct Distance Measurements to Superluminal Radio Sources

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    We present a new technique for directly measuring the distances to superluminal radio sources. By comparing the observed proper motions of components in a parsec scale radio jet to their measured Doppler factors, we can deduce the distance to the radio source independent of the standard rungs in the cosmological distance ladder. This technique requires that the jet angle to the line of sight and the ratio of pattern to flow velocities are sufficiently constrained. We evaluate a number of possibilities for constraining these parameters and demonstrate the technique on a well defined component in the parsec scale jet of the quasar 3C279 (z = 0.536). We find an angular size distance to 3C279 of greater than 1.8 (+0.5,-0.3) n^{1/8} Gpc, where n is the ratio of the energy density in the magnetic field to the energy density in the radiating particles in that jet component. For an Einstein-de Sitter Universe, this measurement would constrain the Hubble constant to be H < 65 n^{-1/8} km/s/Mpc at the two sigma level. Similar measurements on higher redshift sources may help discriminate between cosmological models.Comment: 18 pages, 8 figures, to be published in The Astrophysical Journa

    Schizophrenia and the progression of emotional expression in relation to others

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    Gaining an improved understanding of people diagnosed with schizophrenia has the potential to influence priorities for therapy. Psychosis is commonly understood through the perspective of the medical model. However, the experience of social context surrounding psychosis is not well understood. In this research project we used a phenomenological methodology with a longitudinal design to interview 7 participants across a 12-month period to understand the social experiences surrounding psychosis. Eleven themes were explicated and divided into two phases of the illness experience: (a) transition into emotional shutdown included the experiences of not being acknowledged, relational confusion, not being expressive, detachment, reliving the past, and having no sense of direction; and (b) recovery from emotional shutdown included the experiences of being acknowledged, expression, resolution, independence, and a sense of direction. The experiential themes provide clinicians with new insights to better assess vulnerability, and have the potential to inform goals for therapy

    A simple test for the existence of two accretion modes in Active Galactic Nuclei

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    By analogy to the different accretion states observed in black-hole X-ray binaries (BHXBs), it appears plausible that accretion disks in active galactic nuclei (AGN) undergo a state transition between a radiatively efficient and inefficient accretion flow. If the radiative efficiency changes at some critical accretion rate, there will be a change in the distribution of black hole masses and bolometric luminosities at the corresponding transition luminosity. To test this prediction, I consider the joint distribution of AGN black hole masses and bolometric luminosities for a sample taken from the literature. The small number of objects with low Eddington-scaled accretion rates mdot < 0.01 and black hole masses Mbh < 10^9 Msun constitutes tentative evidence for the existence of such a transition in AGN. Selection effects, in particular those associated with flux-limited samples, systematically exclude objects in particular regions of the black hole mass-luminosity plane. Therefore, they require particular attention in the analysis of distributions of black hole mass, bolometric luminosity, and derived quantities like the accretion rate. I suggest further observational tests of the BHXB-AGN unification scheme which are based on the jet domination of the energy output of BHXBs in the hard state, and on the possible equivalence of BHXB in the very high (or "steep power-law") state showing ejections and efficiently accreting quasars and radio galaxies with powerful radio jets.Comment: Accepted by ApJ; 14 pages, 4 figures, uses emulateap

    Bernstein modes in a weakly relativistic electron-positron plasma

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    The kinetic theory of weakly relativistic electron-positron plasmas, producing dispersion relations for the electrostatic Bernstein modes was addressed. The treatment presented preserves the full momentum dependence of the cyclotron frequency, albeit with a relaxation on the true relativistic form of the distribution function. The implications of this new treatment were confined largely to astrophysical plasmas, where relativistic electronpositron plasmas occur naturally
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