10,941 research outputs found

    System configuration and executive requirements specifications for reusable shuttle and space station/base

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    System configuration and executive requirements specifications for reusable shuttle and space station/bas

    Variable Interstellar Absorption toward the Halo Star HD 219188 - Implications for Small-Scale Interstellar Structure

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    Within the last 10 years, strong, narrow Na I absorption has appeared at v_sun ~ -38 km/s toward the halo star HD 219188; that absorption has continued to strengthen, by a factor 2-3, over the past three years. The line of sight appears to be moving into/through a relatively cold, quiescent intermediate velocity (IV) cloud, due to the 13 mas/yr proper motion of HD 219188; the variations in Na I probe length scales of 2-38 AU/yr. UV spectra obtained with the HST GHRS in 1994-1995 suggest N(H_tot) ~ 4.8 X 10^{17} cm^{-2}, ``halo cloud'' depletions, n_H ~ 25 cm^{-3}, and n_e ~ 0.85-6.2 cm^{-3} (if T ~ 100 K) for the portion of the IV cloud sampled at that time. The relatively high fractional ionization, n_e/n_H >~ 0.034, implies that hydrogen must be partially ionized. The N(Na I)/N(H_tot) ratio is very high; in this case, the variations in Na I do not imply large local pressures or densities.Comment: 12 pages; aastex; to appear in ApJ

    Anophthalmia and microphthalmia

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    Anophthalmia and microphthalmia describe, respectively, the absence of an eye and the presence of a small eye within the orbit. The combined birth prevalence of these conditions is up to 30 per 100,000 population, with microphthalmia reported in up to 11% of blind children. High-resolution cranial imaging, post-mortem examination and genetic studies suggest that these conditions represent a phenotypic continuum. Both anophthalmia and microphthalmia may occur in isolation or as part of a syndrome, as in one-third of cases. Anophthalmia/microphthalmia have complex aetiology with chromosomal, monogenic and environmental causes identified. Chromosomal duplications, deletions and translocations are implicated. Of monogenic causes only SOX2 has been identified as a major causative gene. Other linked genes include PAX6, OTX2, CHX10 and RAX. SOX2 and PAX6 mutations may act through causing lens induction failure. FOXE3 mutations, associated with lens agenesis, have been observed in a few microphthalmic patients. OTX2, CHX10 and RAX have retinal expression and may result in anophthalmia/microphthalmia through failure of retinal differentiation. Environmental factors also play a contributory role. The strongest evidence appears to be with gestational-acquired infections, but may also include maternal vitamin A deficiency, exposure to X-rays, solvent misuse and thalidomide exposure. Diagnosis can be made pre- and post-natally using a combination of clinical features, imaging (ultrasonography and CT/MR scanning) and genetic analysis. Genetic counselling can be challenging due to the extensive range of genes responsible and wide variation in phenotypic expression. Appropriate counselling is indicated if the mode of inheritance can be identified. Differential diagnoses include cryptophthalmos, cyclopia and synophthalmia, and congenital cystic eye. Patients are often managed within multi-disciplinary teams consisting of ophthalmologists, paediatricians and/or clinical geneticists, especially for syndromic cases. Treatment is directed towards maximising existing vision and improving cosmesis through simultaneous stimulation of both soft tissue and bony orbital growth. Mild to moderate microphthalmia is managed conservatively with conformers. Severe microphthalmia and anophthalmia rely upon additional remodelling strategies of endo-orbital volume replacement (with implants, expanders and dermis-fat grafts) and soft tissue reconstruction. The potential for visual development in microphthalmic patients is dependent upon retinal development and other ocular characteristics

    Bohemianism and Urban Regeneration: A Structured Literature Review and Compte Rendu

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    Despite a burgeoning literature, the role of bohemians in the urban milieu and in initiatives toward regeneration remains contested. As a first step toward later modeling and application, we present a thoroughgoing literature review, a short commentary on bohemian phenomena, and suggested readings. Since qualitative sources dominate the field, the review is structured rather than fully systematic in the scientific sense. After discarding innumerable irrelevant and incidental papers, three strands remained for subsequent analysis: “bohemian,” “bohemian + creative-city,” and “smart regeneration.” The first is static or historically contextualized, situated best in the humanities. The last two strands are dynamic and dissect, descriptively or analytically, elements of bohemianism relevant to the urban scene. Wherever and whenever they emerge, radical bohemian artists test existing limits or incite transformative action

    Integrated care and the working record

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    By default, many discussions and specifications of electronic health records or integrated care records often conceptualize the record as a passive information repository. This article presents data from a case study of work in a medical unit in a major metropolitan hospital. It shows how the clinicians tailored, re-presented and augmented clinical information to support their own roles in the delivery of care for individual patients. This is referred to as the working record: a set of complexly interrelated clinician-centred documents that are locally evolved, maintained and used to support delivery of care in conjunction with the more patient-centred chart that will be stored in the medical records department on the patient’s discharge. Implications are drawn for how an integrated care record could support the local tailorability and flexibility that underpin this working record and hence underpin practice

    Co-producing a Community University Knowledge Strategy

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    This community case study describes the process of developing a strategy for community-university engagement, as an example of co-production, and presents the strategy and early outcomes of the work. Based in London, the strategy and the process of co-production are of international relevance in supporting more productive relationships between universities and their cities, as a foundation for repurposing universities for sustainable human progress. The case study is presented in the context of literature related to community engagement with universities and co-production, an area of growing concern as universities seek to strengthen relationships and contribution to sustainable human progress in their home cities. London is one of the world’s great university cities, with more than 40 higher education institutions contributing ground-breaking research and educating students from across the globe. London is also home to vibrant local communities, with a strong tradition of grassroots action, community organization and citizen participation. Community groups and universities have a strong history of working together, often without formal recognition or resources. The Community university Knowledge Strategy for London, known as Collaborate!, was a collaboration between universities and grassroots community groups in London, co-convened by Just Space and University College London (UCL). A series of workshops, guided by two steering committees of community and university members, explored principles for working together, cultural and institutional barriers, decolonization, industrial strategies, community spaces and case studies of good practice. The final conference outlined the basis for a London-wide strategy to enable better engagement between universities and grassroots community groups. The strategy addresses core principles, curriculum, evaluation and evidence, resources, relationship building, governance and structures to support collaboration. Co-production ensured high levels of trust between participants and commitment to the outcomes. Implementation of the strategy actions requires ongoing resources to support intermediary structures to overcome misalignment between universities as large, hierarchical institutions and community groups as dynamic, informal, social organizations

    New Perspective on Galaxy Clustering as a Cosmological Probe: General Relativistic Effects

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    We present a general relativistic description of galaxy clustering in a FLRW universe. The observed redshift and position of galaxies are affected by the matter fluctuations and the gravity waves between the source galaxies and the observer, and the volume element constructed by using the observables differs from the physical volume occupied by the observed galaxies. Therefore, the observed galaxy fluctuation field contains additional contributions arising from the distortion in observable quantities and these include tensor contributions as well as numerous scalar contributions. We generalize the linear bias approximation to relate the observed galaxy fluctuation field to the underlying matter distribution in a gauge-invariant way. Our full formalism is essential for the consistency of theoretical predictions. As our first application, we compute the angular auto correlation of large-scale structure and its cross correlation with CMB temperature anisotropies. We comment on the possibility of detecting primordial gravity waves using galaxy clustering and discuss further applications of our formalism.Comment: 10 pages, 2 figures, accepted for publication in Physical Review

    In defense of Max Planck [Letters to the editor]

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    Charged Randall-Sundrum black holes and N=4 super Yang-Mills in AdS(2)xS(2)

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    We obtain some exact results for black holes in the Randall-Sundrum model with a single brane. We consider an extreme black hole charged with respect to a Maxwell field on the brane. The near-horizon geometry is determined. The induced metric on the brane and the black hole entropy are compared with the predictions of 4d General Relativity. There is good agreement for large black holes, with calculable subleading corrections. As a separate application, the bulk solution provides a gravitational dual for (strongly coupled, large N) N=4 SYM in AdS(2)xS(2) for arbitrary relative size of AdS(2) and S(2).Comment: 13 page

    The Evolving Accretion Disc in the Black Hole X-ray Transient XTE J1859+226

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    We present HST, RXTE, and UKIRT observations of the broad band spectra of the black hole X-ray transient XTE J1859+226 during the decline from its 1999-2000 outburst. Our UV spectra define the 2175A interstellar absorption feature very well and based on its strength we estimate E(B-V)=0.58+/-0.12. Hence we deredden our spectra and follow the evolution of the spectral energy distribution on the decline from outburst. We find that the UV and optical data, and the X-ray thermal component when detectable, can be fit with a simple blackbody model of an accretion disc heated by internal viscosity and X-ray irradiation, and extending to close to the last stable orbit around the black hole, although the actual inner radius cannot be well constrained. During the decline we see the disc apparently evolving from a model with the edge dominated by irradiative heating towards one where viscous heating is dominant everywhere. The outer disc radius also appears to decrease during the decline; we interpret this as evidence of a cooling wave moving inwards and discuss its implications for the disc instability model. Based on the normalisation of our spectral fits we estimate a likely distance range of 4.6-8.0kpc, although a value outside of this range cannot securely be ruled out.Comment: 10 pages including figures. Accepted for publication in MNRA
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