603 research outputs found

    Philosophy with children : helping designers cooperate with children

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    Engaging children in design through in-depth interviews is coming to prominence in the IDC community, which increasingly engages with issues about understanding the children's world. To date, research in this area has primarily focused on engaging children using techniques somehow similar to adult-techniques (moodboards, brainstorming, laddering,...). However, questioning or interviewing children is fraught with difficulties. The proposed workshop seeks to explore where and how a philosophy with children methodology can be adapted for design, exploring themes such as Socratic Attitudes, wondering, and question types. This workshop aims to build an interdisciplinary community of researchers, designers, and practitioners to share and discuss their work and experiences

    Calcium-loaded hydrophilic hypercrosslinked polymers for extremely high defluoridation capacity via multiple uptake mechanisms

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    Hydrophilic hypercrosslinked porous polymer networks were synthesised from 2,2-biphenol (HHCP1) and bisphenol A (HHCP2) monomers, which were assessed for remediation of highly fluoridated water. The networks were hydrophilic and the hypercrosslinking radically altered the acidity of protonation sites within the polymeric scaffolds. The polymers were metallated to produce novel, hybrid Ca-loaded adsorbents. The metal-loading affected the electron distribution of the quinonoid structures formed during polymerisation. HHCP1 had a greater exchange capacity (6.34 ± 0.17 mmol g−1) and adsorbed more Ca2+, yet retained much of its original surface area, whereas HHCP2 was rendered non-porous upon metallation. Ca-loading included covalent interactions and formation of crystalline CaCO3 (vaterite), from preferential CO2 binding under ambient conditions. Both networks were effective defluoridating media, with Ca-loaded HHCP1 exhibiting a capacity among the highest yet reported for any extractant (267 ± 34 mg g−1). HHCP2-Ca had a lower capacity of 96.2 ± 10 mg g−1, but faster uptake kinetics and was more effective at lower concentrations, attributed to stronger binding interactions. Crystalline CaF2 (fluorite) was the dominant fluoride species formed, from both vaterite and covalently bound Ca. The networks could be used in a dynamic column system, extracted fluoride in the presence of multiple coexisting anions and were regenerable, with a potential pathway demonstrated for recovery of the adsorbed fluoride

    Is the Sun Embedded in a Typical Interstellar Cloud?

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    The physical properties and kinematics of the partially ionized interstellar material near the Sun are typical of warm diffuse clouds in the solar vicinity. The interstellar magnetic field at the heliosphere and the kinematics of nearby clouds are naturally explained in terms of the S1 superbubble shell. The interstellar radiation field at the Sun appears to be harder than the field ionizing ambient diffuse gas, which may be a consequence of the low opacity of the tiny cloud surrounding the heliosphere. The spatial context of the Local Bubble is consistent with our location in the Orion spur.Comment: "From the Outer Heliosphere to the Local Bubble", held at International Space Sciences Institute, October 200

    Highly-ordered onion micelles made from amphiphilic highly-branched copolymers

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    Uniform onion micelles formed from up to ten nano-structured polymer layers were produced by the aqueous self-assembly of highly-branched copolymers. Highly-branched poly(alkyl methacrylate)s were chain extended with poly(acrylic acid) in a two-step reversible addition–fragmentation chain transfer-self-condensing vinyl polymerization (RAFT-SCVP) in solution. The resulting polymers were dispersed into water from oxolane (THF) using a self-organized precipitation-like method and the self-assembled particles were studied by phase-analysis light scattering, small-angle neutron scattering, and electron microscopy techniques. The relative hydrophobicity of the blocks was varied by changing the alkyl methacrylate (methyl, butyl, or lauryl) and this was found to affect the morphology of the particles. Only the poly(butyl methacrylate)-containing macromolecule formed an onion micelle structure. The formation of this morphology was observed to depend on: the evaporation of the good solvent (THF) during the self-assembly process causing kinetic trapping of structures; the pH of the aqueous phase; and also on the ratio of hydrophobic to hydrophilic segments within the copolymer. The lamellar structure could be removed by annealing the dispersion above the glass transition temperature of the poly(butyl methacrylate). To exemplify how these onion micelles can be used to encapsulate and release an active compound, a dye, rhodamine B (Rh B), was encapsulated and released. The release behaviour was dependent on the morphology of the particles. Particles formed containing the poly(methyl methacrylate) or poly(lauryl methacrylate) core did not form onions and although these materials absorbed Rh B, it was continuously released at room temperature. On the other hand, the lamellar structure formed from branch-poly(butyl methacrylate)-[poly(butyl methacrylate)-block-poly(acrylic acid)] allowed for encapsulation of approximately 45% of the dye, without release, until heating disrupted the lamellar structure

    General distress, hopelessness-suicidal ideation and worrying in adolescence:concurrent and predictive validity of a symptom-level bifactor model for clinical diagnoses

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    BACKGROUND: Clinical disorders often share common symptoms and aetiological factors. Bifactor models acknowledge the role of an underlying general distress component and more specific sub-domains of psychopathology which specify the unique components of disorders over and above a general factor. METHODS: A bifactor model jointly calibrated data on subjective distress from The Mood and Feelings Questionnaire and the Revised Children's Manifest Anxiety Scale. The bifactor model encompassed a general distress factor, and specific factors for (a) hopelessness-suicidal ideation, (b) generalised worrying and (c) restlessness-fatigue at age 14 which were related to lifetime clinical diagnoses established by interviews at ages 14 (concurrent validity) and current diagnoses at 17 years (predictive validity) in a British population sample of 1159 adolescents. RESULTS: Diagnostic interviews confirmed the validity of a symptom-level bifactor model. The underlying general distress factor was a powerful but non-specific predictor of affective, anxiety and behaviour disorders. The specific factors for hopelessness-suicidal ideation and generalised worrying contributed to predictive specificity. Hopelessness-suicidal ideation predicted concurrent and future affective disorder; generalised worrying predicted concurrent and future anxiety, specifically concurrent generalised anxiety disorders. Generalised worrying was negatively associated with behaviour disorders. LIMITATIONS: The analyses of gender differences and the prediction of specific disorders was limited due to a low frequency of disorders other than depression. CONCLUSIONS: The bifactor model was able to differentiate concurrent and predict future clinical diagnoses. This can inform the development of targeted as well as non-specific interventions for prevention and treatment of different disorders

    Low-Luminosity Accretion in Black Hole X-ray Binaries and Active Galactic Nuclei

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    At luminosities below a few percent of Eddington, accreting black holes switch to a hard spectral state which is very different from the soft blackbody-like spectral state that is found at higher luminosities. The hard state is well-described by a two-temperature, optically thin, geometrically thick, advection-dominated accretion flow (ADAF) in which the ions are extremely hot (up to 101210^{12} K near the black hole), the electrons are also hot (∼109−10.5\sim10^{9-10.5} K), and thermal Comptonization dominates the X-ray emission. The radiative efficiency of an ADAF decreases rapidly with decreasing mass accretion rate, becoming extremely low when a source reaches quiescence. ADAFs are expected to have strong outflows, which may explain why relativistic jets are often inferred from the radio emission of these sources. It has been suggested that most of the X-ray emission also comes from a jet, but this is less well established.Comment: To appear in "From X-ray Binaries to Quasars: Black Hole Accretion on All Mass Scales" edited by T. Maccarone, R. Fender, L. Ho, to be published as a special edition of "Astrophysics and Space Science" by Kluwe

    Atomic X-ray Spectroscopy of Accreting Black Holes

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    Current astrophysical research suggests that the most persistently luminous objects in the Universe are powered by the flow of matter through accretion disks onto black holes. Accretion disk systems are observed to emit copious radiation across the electromagnetic spectrum, each energy band providing access to rather distinct regimes of physical conditions and geometric scale. X-ray emission probes the innermost regions of the accretion disk, where relativistic effects prevail. While this has been known for decades, it also has been acknowledged that inferring physical conditions in the relativistic regime from the behavior of the X-ray continuum is problematic and not satisfactorily constraining. With the discovery in the 1990s of iron X-ray lines bearing signatures of relativistic distortion came the hope that such emission would more firmly constrain models of disk accretion near black holes, as well as provide observational criteria by which to test general relativity in the strong field limit. Here we provide an introduction to this phenomenon. While the presentation is intended to be primarily tutorial in nature, we aim also to acquaint the reader with trends in current research. To achieve these ends, we present the basic applications of general relativity that pertain to X-ray spectroscopic observations of black hole accretion disk systems, focusing on the Schwarzschild and Kerr solutions to the Einstein field equations. To this we add treatments of the fundamental concepts associated with the theoretical and modeling aspects of accretion disks, as well as relevant topics from observational and theoretical X-ray spectroscopy.Comment: 63 pages, 21 figures, Einstein Centennial Review Article, Canadian Journal of Physics, in pres
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