416 research outputs found

    Emulation Techniques for Scenario and Classical Control Design of Tokamak Plasmas

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    The optimisation of scenarios and design of real-time-control in tokamaks, especially for machines still in design phase, requires a comprehensive exploration of solutions to the Grad-Shafranov (GS) equation over a high-dimensional space of plasma and coil parameters. Emulators can bypass the numerical issues in the GS equation, if a large enough library of equilibria is available. We train an ensemble of neural networks to emulate the typical shape-control targets (separatrix at midplane, X-points, divertor strike point, flux expansion, poloidal beta) as a function of plasma parameters and active coil currents for the range of plasma configurations relevant to spherical tokamaks with a super-X divertor, with percent-level accuracy. This allows a quick calculation of the classical-control shape matrices, potentially allowing real-time calculation at any point in a shot with sub-ms latency. We devise a hyperparameter sampler to select the optimal network architectures and quantify uncertainties on the model predictions. To generate the relevant training set, we devise a Markov-Chain Monte Carlo algorithm to produce large libraries of forward Grad-Shafranov solutions without the need for user intervention. The algorithm promotes equilibria with desirable properties, while avoiding parameter combinations resulting in problematic profiles or numerical issues in the integration of the GS equation.Comment: Physics of Plasmas in print, ICDDPS-4 special issue, 15 pages, 6 figure

    Multi-level evidence of an allelic hierarchy of USH2A variants in hearing, auditory processing and speech/language outcomes.

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    Language development builds upon a complex network of interacting subservient systems. It therefore follows that variations in, and subclinical disruptions of, these systems may have secondary effects on emergent language. In this paper, we consider the relationship between genetic variants, hearing, auditory processing and language development. We employ whole genome sequencing in a discovery family to target association and gene x environment interaction analyses in two large population cohorts; the Avon Longitudinal Study of Parents and Children (ALSPAC) and UK10K. These investigations indicate that USH2A variants are associated with altered low-frequency sound perception which, in turn, increases the risk of developmental language disorder. We further show that Ush2a heterozygote mice have low-level hearing impairments, persistent higher-order acoustic processing deficits and altered vocalizations. These findings provide new insights into the complexity of genetic mechanisms serving language development and disorders and the relationships between developmental auditory and neural systems

    Countdown to 2015 country case studies: What have we learned about processes and progress towards MDGs 4 and 5?

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    BACKGROUND: Countdown to 2015 was a multi-institution consortium tracking progress towards Millennium Development Goals (MDGs) 4 and 5. Case studies to explore factors contributing to progress (or lack of progress) in reproductive, maternal, newborn and child health (RMNCH) were undertaken in: Afghanistan, Bangladesh, China, Ethiopia, Kenya, Malawi, Niger, Pakistan, Peru, and Tanzania. This paper aims to identify cross-cutting themes on how and why these countries achieved or did not achieve MDG progress. METHODS: Applying a standard evaluation framework, analyses of impact, coverage and equity were undertaken, including a mixed methods analysis of how these were influenced by national context and coverage determinants (including health systems, policies and financing). RESULTS: The majority (7/10) of case study countries met MDG-4 with over two-thirds reduction in child mortality, but none met MDG-5a for 75 % reduction in maternal mortality, although six countries achieved >75 % of this target. None achieved MDG-5b regarding reproductive health. Rates of reduction in neonatal mortality were half or less that for post-neonatal child mortality. Coverage increased most for interventions administered at lower levels of the health system (e.g., immunisation, insecticide treated nets), and these experienced substantial political and financial support. These interventions were associated with ~30-40 % of child lives saved in 2012 compared to 2000, in Ethiopia, Malawi, Peru and Tanzania. Intrapartum care for mothers and newborns - which require higher-level health workers, more infrastructure, and increased community engagement - showed variable increases in coverage, and persistent equity gaps. Countries have explored different approaches to address these problems, including shifting interventions to the community setting and tasks to lower-level health workers. CONCLUSIONS: These Countdown case studies underline the importance of consistent national investment and global attention for achieving improvements in RMNCH. Interventions with major global investments achieved higher levels of coverage, reduced equity gaps and improvements in associated health outcomes. Given many competing priorities for the Sustainable Development Goals era, it is essential to maintain attention to the unfinished RMNCH agenda, particularly health systems improvements for maternal and neonatal outcomes where progress has been slower, and to invest in data collection for monitoring progress and for rigorous analyses of how progress is achieved in different contexts

    "An infinitude of Possible Worlds": towards a research method for hypertext fiction

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    While the investigation of creative writing as a research method is gathering apace, little work has been done into the specific case of hypertext fiction (fiction written through a digital medium). This paper argues that, while there remain certain similarities between paper-based and digital texts, fundamental differences in design and construction remain. If hypertext fictions are to be successfully understood, then the role and purpose of the digital writer needs to be more fully analysed as part of the creative process. This paper argues that Possible Worlds Theory offers a way forward. With its focus on the ontological structures created by hypertext fiction, Possible World Theory actively embraces narrative indeterminacy and ontological changeability. In this sense the method provides a structured means by which the creative manipulation of the unique affordances of a digital medium by a writer can be theorised

    NIK Stabilization in Osteoclasts Results in Osteoporosis and Enhanced Inflammatory Osteolysis

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    Maintenance of healthy bone requires the balanced activities of osteoclasts (OCs), which resorb bone, and osteoblasts, which build bone. Disproportionate action of OCs is responsible for the bone loss associated with postmenopausal osteoporosis and rheumatoid arthritis. NF-κB inducing kinase (NIK) controls activation of the alternative NF-κB pathway, a critical pathway for OC differentiation. Under basal conditions, TRAF3-mediated NIK degradation prevents downstream signaling, and disruption of the NIK:TRAF3 interaction stabilizes NIK leading to constitutive activation of the alternative NF-κB pathway.Using transgenic mice with OC-lineage expression of NIK lacking its TRAF3 binding domain (NT3), we now find that alternative NF-κB activation enhances not only OC differentiation but also OC function. Activating NT3 with either lysozyme M Cre or cathepsinK Cre causes high turnover osteoporosis with increased activity of OCs and osteoblasts. In vitro, NT3-expressing precursors form OCs more quickly and at lower doses of RANKL. When cultured on bone, they exhibit larger actin rings and increased resorptive activity. OC-specific NT3 transgenic mice also have an exaggerated osteolytic response to the serum transfer model of arthritis.Constitutive activation of NIK drives enhanced osteoclastogenesis and bone resorption, both in basal conditions and in response to inflammatory stimuli

    Molecular Mechanisms of Bortezomib Resistant Adenocarcinoma Cells

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    Bortezomib (Velcade™) is a reversible proteasome inhibitor that is approved for the treatment of multiple myeloma (MM). Despite its demonstrated clinical success, some patients are deprived of treatment due to primary refractoriness or development of resistance during therapy. To investigate the role of the duration of proteasome inhibition in the anti-tumor response of bortezomib, we established clonal isolates of HT-29 adenocarcinoma cells adapted to continuous exposure of bortezomib. These cells were ∼30-fold resistant to bortezomib. Two novel and distinct mutations in the β5 subunit, Cys63Phe, located distal to the binding site in a helix critical for drug binding, and Arg24Cys, found in the propeptide region were found in all resistant clones. The latter mutation is a natural variant found to be elevated in frequency in patients with MM. Proteasome activity and levels of both the constitutive and immunoproteasome were increased in resistant cells, which correlated to an increase in subunit gene expression. These changes correlated with a more rapid recovery of proteasome activity following brief exposure to bortezomib. Increased recovery rate was not due to increased proteasome turnover as similar findings were seen in cells co-treated with cycloheximide. When we exposed resistant cells to the irreversible proteasome inhibitor carfilzomib we noted a slower rate of recovery of proteasome activity as compared to bortezomib in both parental and resistant cells. Importantly, carfilzomib maintained its cytotoxic potential in the bortezomib resistant cell lines. Therefore, resistance to bortezomib, can be overcome with irreversible inhibitors, suggesting prolonged proteasome inhibition induces a more potent anti-tumor response

    Are anti-fouling effects in coralline algae species specific?

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    The crustose coralline algae are susceptible to be covered by other algae, which in turn can be affected by anti-fouling effects. In this study the hypothesis tested was that these algae can inhibit the growth of epiphytes in a species specific way. In the laboratory, propagules of Sargassum furcatum and Ulva fasciata were liberated and cultivated on pieces of coralline algae and slide covers (controls) and their survival and growth were compared. Spongites and Hydrolithon significantly inhibited the growth of U. fasciata but not Sargassum. In the field, pieces of three species of live and dead coralline algae and their copies in epoxy putty discs were fixed on the rock. After one month epiphytic algae were identified and their dry mass quantified. Lithophyllum did not affect the epiphyte growth. In contrast Spongites and an unidentified coralline significantly inhibited the growth of Enteromorpha spp., Ulva fasciata and Hincksia mitchelliae. Colpomenia sinuosa was absent on all living crusts, but present on controls. Results show that the epiphyte-host relation depends on the species that are interacting. The sloughing of superficial cells of coralline crusts points to the possible action of physical anti-fouling effect, though a chemical one is not rejected.As algas calcárias crostosas são susceptíveis ao recobrimento por outras algas, entretanto, estas podem ser afetadas por efeitos anti-incrustantes. Neste estudo foi testada a hipótese de que estas algas possam inibir o crescimento somente de algumas espécies de epífitas. No laboratório, propágulos de Sargassum furcatum e Ulva fasciata foram liberados e cultivados sobre pedaços de algas calcárias e lamínulas de microscopia (controle) e as suas sobrevivência e crescimento comparadas. Spongites e Hydrolithon inibiram significativamente o crescimento de U. fasciata, mas não de Sargassum. No campo, pedaços de três espécies de algas calcárias vivas, mortas e cópias destas em discos de massa epóxi foram fíxos na rocha. Após um mês as algas epífitas foram identificadas e sua massa seca quantificada. Lithophyllum não inibiu o crescimento das epífitas, em contraste Spongites e outra coralinácea indeterminada inibiram o crescimento de Enteromorpha spp., Ulva fasciata e Hincksia mitchelliae. Colpomenia sinuosa esteve sempre ausente sobre as crostas vivas, porém presente nos controles. Resultados demonstram que a relação epífita-hospedeiro depende das espécies que estejam interagindo. O desprendimento de células superficiais das crostas coralináceas aponta para um possível efeito físico anti-incrustante, não se excluindo o químico

    Eef1a2 Promotes Cell Growth, Inhibits Apoptosis and Activates JAK/STAT and AKT Signaling in Mouse Plasmacytomas

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    The canonical function of EEF1A2, normally expressed only in muscle, brain, and heart, is in translational elongation, but recent studies suggest a non-canonical function as a proto-oncogene that is overexpressed in a variety of solid tumors including breast and ovary. Transcriptional profiling of a spectrum of primary mouse B cell lineage neoplasms showed that transcripts encoding EEF1A2 were uniquely overexpressed in plasmacytomas (PCT), tumors of mature plasma cells. Cases of human multiple myeloma expressed significantly higher levels of EEF1A2 transcripts than normal bone marrow plasma cells. High-level expression was also a feature of a subset of cell lines developed from mouse PCT and from the human MM.Heightened expression of EEF1A2 was not associated with increased copy number or coding sequence mutations. shRNA-mediated knockdown of Eef1a2 transcripts and protein was associated with growth inhibition due to delayed G1-S progression, and effects on apoptosis that were seen only under serum-starved conditions. Transcriptional profiles and western blot analyses of knockdown cells revealed impaired JAK/STAT and PI3K/AKT signaling suggesting their contributions to EEF1A2-mediated effects on PCT induction or progression.EEF1A2 may play contribute to the induction or progression of some PCT and a small percentage of MM. Eef1a2 could also prove to be a useful new marker for a subset of MM and, ultimately, a possible target for therapy
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