1,148 research outputs found

    Using Automatic Differentiation for Adjoint CFD Code Development

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    This paper addresses the concerns of CFD code developers who are facing the task of creating a discrete adjoint CFD code for design optimisation. It discusses how the development of such a code can be greatly eased through the selective use of Automatic Differentiation, and how the software development can be subjected to a sequence of checks to ensure the correctness of the final software

    Molecular phylogeny of the Notostraca

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    We used a combined analysis of one nuclear (28S rDNA) and three mitochondrial markers (COI, 12S rDNA, 16S rDNA) to infer the molecular phylogeny of the Notostraca, represented by samples from the six continents that are inhabited by this group of branchiopod crustaceans. Our results confirm the monophyly of both extant notostracan genera Triops and Lepidurus with good support in model based and maximum parsimony analyses. We used branchiopod fossils as a calibration to infer divergence times among notostracan lineages and accounted for rate heterogeneity among lineages by applying relaxed-clock models. Our divergence date estimates indicate an initial diversification into the genera Triops and Lepidurus in the Mesozoic, most likely at a minimum age of 152.3–233.5 Ma, i.e., in the Triassic or Jurassic. Implications for the interpretation of fossils and the evolution of notostracan morphology are discussed. We further use the divergence date estimates to formulate a biogeographic hypothesis that explains distributions of extant lineages predominantly by overland dispersal routes. We identified an additional hitherto unrecognised highly diverged lineage within Lepidurus apus lubbocki and three additional previously unknown major lineages within Triops. Within T. granarius we found deep differentiation, with representatives distributed among three major phylogenetic lineages. One of these major lineages comprises T. cancriformis, the T. mauritanicus species group and two hitherto unrecognised T. granarius lineages. Samples that were morphologically identified as T. granarius diverged from the most basal nodes within this major lineage, and divergence dates suggested an approximate age of 23.7– 49.6 Ma for T. cancriformis, indicating the need for a taxonomic revision of Triassic and Permian fossils that are currently attributed to the extant T. cancriformis.We thus elevate T. cancriformis minor to full species status as Triops minor Trusheim, 1938 and include in this species the additional Upper Triassic samples that were attributed to T. cancriformis. We further elevate T. cancriformis permiensis to full species status as Triops permiensis Gand et al., 1997

    Aerosol meteorology of Maritime Continent for the 2012 7SEAS southwest monsoon intensive study - Part 2: Philippine receptor observations of fine-scale aerosol behavior

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    Abstract. The largest 7 Southeast Asian Studies (7SEAS) operations period within the Maritime Continent (MC) occurred in the August–September 2012 biomass burning season. Data included were observations aboard the M/Y Vasco, dispatched to the Palawan Archipelago and Sulu Sea of the Philippines for September 2012. At these locations, the Vasco observed MC smoke and pollution entering the southwest monsoon (SWM) monsoonal trough. Here we describe the research cruise findings and the finer-scale aerosol meteorology of this convectively active region. This 2012 cruise complemented a 2-week cruise in 2011 and was generally consistent with previous findings in terms of how smoke emission and transport related to monsoonal flows, tropical cyclones (TC), and the covariance between smoke transport events and the atmosphere's thermodynamic structure. Biomass burning plumes were usually mixed with significant amounts of anthropogenic pollution. Also key to aerosol behavior were squall lines and cold pools propagating across the South China Sea (SCS) and scavenging aerosol particles in their path. However, the 2012 cruise showed much higher modulation in aerosol frequency than its 2011 counterpart. Whereas in 2011 large synoptic-scale aerosol events transported high concentrations of smoke into the Philippines over days, in 2012 measured aerosol events exhibited a much shorter-term variation, sometimes only 3–12 h. Strong monsoonal flow reversals were also experienced in 2012. Nucleation events in cleaner and polluted conditions, as well as in urban plumes, were observed. Perhaps most interestingly, several cases of squall lines preceding major aerosol events were observed, as opposed to 2011 observations where these lines largely scavenged aerosol particles from the marine boundary layer. Combined, these observations indicate pockets of high and low particle counts that are not uncommon in the region. These perturbations are difficult to observe by satellite and very difficult to model. Indeed, the Navy Aerosol Analysis and Prediction System (NAAPS) simulations captured longer period aerosol events quite well but largely failed to capture the timing of high-frequency phenomena. Ultimately, the research findings of these cruises demonstrate the real world challenges of satellite-based missions, significant aerosol life cycle questions such as those the future Aerosol/Clouds/Ecosystems (ACE) will investigate, and the importance of small-scale phenomena such as sea breezes, squall lines, and nucleation events embedded within SWM patterns in dominating aerosol life cycle and potential relationships to clouds

    Ethical and methodological issues in engaging young people living in poverty with participatory research methods

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    This paper discusses the methodological and ethical issues arising from a project that focused on conducting a qualitative study using participatory techniques with children and young people living in disadvantage. The main aim of the study was to explore the impact of poverty on children and young people's access to public and private services. The paper is based on the author's perspective of the first stage of the fieldwork from the project. It discusses the ethical implications of involving children and young people in the research process, in particular issues relating to access and recruitment, the role of young people's advisory groups, use of visual data and collection of data in young people's homes. The paper also identifies some strategies for addressing the difficulties encountered in relation to each of these aspects and it considers the benefits of adopting participatory methods when conducting research with children and young people

    “It’s the most important thing - I mean the schooling”: Father involvement in the education of children with autism

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    Father involvement in education has been shown to result in a range of positive outcomes for typically developing children. However, the nature of paternal involvement in the education of children with disabilities and especially autism has been under-researched and is little understood. This study aimed to explore the nature of the involvement of 25 UK fathers in the education and their children with autism, aged up to 19 years through the use of semi-structured interviews. Findings showed that fathers were highly engaged both directly and indirectly across several dimensions of their children’s education and schooling. Key areas of indirect engagement were involvement in administrative processes necessary for securing an appropriate educational placement; facilitating daily access to school and general support of children’s progress through attendance at school-based meetings and events. Direct support for learning occurred through homework assistance and working on school-related goals. Findings are discussed in relation to diversity and generative models of fatherhood. Implications for greater father inclusion in the education of children with autism are explored with reference to a gender-differentiated approach

    An impact and feasibility evaluation of a 6 week (9 hour) active play intervention on fathers' engagement with their preschool children: A feasibility study

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    Research has demonstrated the benefits of father involvement with their children and a link between uninvolved fatherhood and societal problems. Children’s Centres (n=15) received 6 x 90 minute active play sessions designed to foster six aspects of parental engagement. Fathers’ engagement and attitudes to child PA were measured pre- and post-intervention via questionnaire. Acceptability of the intervention was explored through participant and staff focus groups. Results showed no effect on overall time fathers spent with their child during the week (t (36) = 0.178, p = 0.860) and the weekend (t (36) =1.166, p = 0.252). Qualitative results demonstrated the sessions provided opportunities for fathers to spend quality time with their children. Parenting self-efficacy increased across the subscale control, t (36) = -2.97, p = 0.04. Fathers increased awareness of their role in motivating their child to play (z = -2.46, p = 0.01). Further longitudinal research is recommended. Key Words: fathers’ engagement; childcare settings; parenting programmes; active play; parenting self-efficac

    Gravitational collapse with tachyon field and barotropic fluid

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    A particular class of space-time, with a tachyon field, \phi, and a barotropic fluid constituting the matter content, is considered herein as a model for gravitational collapse. For simplicity, the tachyon potential is assumed to be of inverse square form i.e., V(\phi) \sim \phi^{-2}. Our purpose, by making use of the specific kinematical features of the tachyon, which are rather different from a standard scalar field, is to establish the several types of asymptotic behavior that our matter content induces. Employing a dynamical system analysis, complemented by a thorough numerical study, we find classical solutions corresponding to a naked singularity or a black hole formation. In particular, there is a subset where the fluid and tachyon participate in an interesting tracking behaviour, depending sensitively on the initial conditions for the energy densities of the tachyon field and barotropic fluid. Two other classes of solutions are present, corresponding respectively, to either a tachyon or a barotropic fluid regime. Which of these emerges as dominant, will depend on the choice of the barotropic parameter, \gamma. Furthermore, these collapsing scenarios both have as final state the formation of a black hole.Comment: 18 pages, 7 figures. v3: minor changes. Final version to appear in GR

    Informal community support for parents of pre-school children: A comparative study investigating the subjective experience of parents attending community-based toddler groups in different socio-economic situations

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    "Within the United Kingdom, the importance of the appropriate parenting of children in their early years has received significant political support. However, it has been found that positive outcomes for young children, in terms of their present experience and future life chances, are often significantly weakened by the impact of poverty. A phenomenological scoping study was undertaken to explore the reasons why parents living in poverty access informal social support networks, in the form of community-based toddler groups. The study found that engagement with these networks has value for parents in terms of their mental well-being and their peer education, both of which support their ability to parent a young child appropriately.
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