1,573 research outputs found

    Seven lessons from manyfield inflation in random potentials

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    We study inflation in models with many interacting fields subject to randomly generated scalar potentials. We use methods from non-equilibrium random matrix theory to construct the potentials and an adaption of the ‘transport method’ to evolve the two-point correlators during inflation. This construction allows, for the first time, for an explicit study of models with up to 100 interacting fields supporting a period of ‘approximately saddle-point’ inflation. We determine the statistical predictions for observables by generating over 30,000 models with 2–100 fields supporting at least 60 efolds of inflation. These studies lead us to seven lessons: i) Manyfield inflation is not single-field inflation, ii) The larger the number of fields, the simpler and sharper the predictions, iii) Planck compatibility is not rare, but future experiments may rule out this class of models, iv) The smoother the potentials, the sharper the predictions, v) Hyperparameters can transition from stiff to sloppy, vi) Despite tachyons, isocurvature can decay, vii) Eigenvalue repulsion drives the predictions. We conclude that many of the ‘generic predictions’ of single-field inflation can be emergent features of complex inflation models

    A new class of de Sitter vacua in type IIB large volume compactifications

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    We construct a new class of metastable de Sitter vacua of flux compactifications of type IIB string theory. These solutions provide a natural extension of the `Large Volume Scenario' anti-de Sitter vacua, and can analogously be realised at parametrically large volume and weak string coupling, using standard N=1{\cal N}=1 supergravity. For these new vacua, a positive vacuum energy is achieved from the inclusion of a small amount of flux-induced supersymmetry breaking in the complex structure and axio-dilaton sector, and no additional `uplift' contribution (e.g.~from anti-branes) is required. We show that the approximate no-scale structure of the effective theory strongly influences the spectrum of the stabilised moduli: one complex structure modulus remains significantly lighter than the supersymmetry breaking scale, and metastability requires only modest amounts of tuning. After discussing these general results, we provide a recipe for constructing de Sitter vacua on a given compactification manifold, and give an explicit example of a de Sitter vacuum for the compactification on the Calabi-Yau orientifold realised in CP111694\mathbb{CP}^4_{11169}. Finally, we note that these solutions have intriguing implications for phenomenology, predicting no superpartners in the spectrum below ∼\sim50 TeV, and no WIMP dark matter.Comment: 34 page

    A new bound on axion-like particles

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    Axion-like particles (ALPs) and photons can quantum mechanically interconvert when propagating through magnetic fields, and ALP-photon conversion may induce oscillatory features in the spectra of astrophysical sources. We use deep (370 ks), short frame time Chandra observations of the bright nucleus at the centre of the radio galaxy M87 in the Virgo cluster to search for signatures of light ALPs. The absence of substantial irregularities in the X-ray power-law spectrum leads to a new upper limit on the photon-ALP coupling, gaγg_{a\gamma}: using a conservative model of the cluster magnetic field consistent with Faraday rotation measurements from M87 and M84, we find gaγ<2.6×10−12g_{a \gamma} < 2.6\times10^{-12} GeV−1^{-1} at 95% confidence level for ALP masses ma≤10−13m_a \leq 10^{-13} eV. Other consistent magnetic field models lead to stronger limits of gaγ≲1.1g_{a \gamma} \lesssim 1.1--1.5×10−121.5 \times 10^{-12} GeV−1^{-1}. These bounds are all stronger than the limit inferred from the absence of a gamma-ray burst from SN1987A, and rule out a substantial fraction of the parameter space accessible to future experiments such as ALPS-II and IAXO

    A Darker Side of Creative Entrepreneurship

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    This article aims to contrast positive interpretations of enterprise in creative work, which are characterised by freedom, autonomy and choice with less optimistic accounts of the nature of enterprise in the creative industries. By examining extant literature, it illustrates the entrepreneurial responses of designers to instable and dynamic market conditions. It charts how designers adapt to market forces by reconciling creative and commercial pressures, enhancing their labour mobility and commercialising their own labour potential. This article argues that designer’s normative feelings about their work enable them to reconcile the challenging aspects of their work

    Boundaries of Semantic Distraction: Dominance and Lexicality Act at Retrieval

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    Three experiments investigated memory for semantic information with the goal of determining boundary conditions for the manifestation of semantic auditory distraction. Irrelevant speech disrupted the free recall of semantic category-exemplars to an equal degree regardless of whether the speech coincided with presentation or test phases of the task (Experiment 1) and occurred regardless of whether it comprised random words or coherent sentences (Experiment 2). The effects of background speech were greater when the irrelevant speech was semantically related to the to-be-remembered material, but only when the irrelevant words were high in output dominance (Experiment 3). The implications of these findings in relation to the processing of task material and the processing of background speech is discussed

    Development and psychometric testing of the clinical leadership needs analysis (CLeeNA) instrument for nurses and midwives

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    Aim: The aim of this study is to report the development and psychometric testing of the clinical leadership needs analysis instrument (CLeeNA). Background: Limited emphasis is placed on the clinical leadership needs of nurses and midwives that are fundamental to supporting the delivery of high quality, safe patient care. Methods: A development and validation study of CLeeNA was undertaken using cross-sectional data. A sample of 324 registered nurses and midwives completed the questionnaire using a 7-point adjectival scale. Principal component analysis was conducted to explore scale grouping of items (n = 103 items). Results: Principal component analysis, item reduction and parallel analysis on the items of the instrument resulted in seven factors consisting of 56 items. These factors were identified as: Staff and Care Delivery; Technology and Care Initiatives; Self and Team Development; Standards of Care; Financial and Service Management; Leadership and Clinical Practice; Patient Safety and Risk Management. Conclusion: The identified factors are reflective of an ever-changing health care environment. Implications for Nursing Management: Potentially, after further testing, this instrument could be used by nursing management and educators to measure clinical leadership needs, inform the design of clinical leadership training programmes and provide valuable information about health care leadership development

    Satisfaction with democracy and voter turnout

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    Numerous studies conclude that countries in which citizens express higher levels of satisfaction with democracy also tend to display higher levels of voter turnout in national elections. Yet it is difficult to draw causal inferences from this positive cross-sectional relationship, because democracies feature many historical, cultural, and institutional differences that are not easily controlled for in cross-sectional comparisons. We apply an alternative, temporal approach to this issue by asking the question: Are over-time declines (increases) in aggregate levels of satisfaction within democracies associated with increases (declines) in levels of voter turnout within these democracies? Our temporal analysis of this relationship in 12 democracies over the period 1976–2011 reveals a pattern that is the opposite of that suggested by previous cross-sectional studies: namely, we find that over-time increases in citizens’ satisfaction with democracy are associated with significant decreases in voter turnout in national elections in these countries. </jats:p

    Severe childhood malaria syndromes defined by plasma proteome profiles

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    BACKGROUND Cerebral malaria (CM) and severe malarial anemia (SMA) are the most serious life-threatening clinical syndromes of Plasmodium falciparum infection in childhood. Therefore it is important to understand the pathology underlying the development of CM and SMA, as opposed to uncomplicated malaria (UM). Different host responses to infection are likely to be reflected in plasma proteome-patterns that associate with clinical status and therefore provide indicators of the pathogenesis of these syndromes. METHODS AND FINDINGS Plasma and comprehensive clinical data for discovery and validation cohorts were obtained as part of a prospective case-control study of severe childhood malaria at the main tertiary hospital of the city of Ibadan, an urban and densely populated holoendemic malaria area in Nigeria. A total of 946 children participated in this study. Plasma was subjected to high-throughput proteomic profiling. Statistical pattern-recognition methods were used to find proteome-patterns that defined disease groups. Plasma proteome-patterns accurately distinguished children with CM and with SMA from those with UM, and from healthy or severely ill malaria-negative children. CONCLUSIONS We report that an accurate definition of the major childhood malaria syndromes can be achieved using plasma proteome-patterns. Our proteomic data can be exploited to understand the pathogenesis of the different childhood severe malaria syndromes

    Capture the fracture: a best practice framework and global campaign to break the fragility fracture cycle

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    Summary The International Osteoporosis Foundation (IOF) Capture the Fracture Campaign aims to support implementation of Fracture Liaison Services (FLS) throughout the world. Introduction FLS have been shown to close the ubiquitous secondary fracture prevention care gap, ensuring that fragility fracture sufferers receive appropriate assessment and intervention to reduce future fracture risk. Methods Capture the Fracture has developed internationally endorsed standards for best practice, will facilitate change at the national level to drive adoption of FLS and increase awareness of the challenges and opportunities presented by secondary fracture prevention to key stakeholders. The Best Practice Framework (BPF) sets an international benchmark for FLS, which defines essential and aspirational elements of service delivery. Results The BPF has been reviewed by leading experts from many countries and subject to beta-testing to ensure that it is internationally relevant and fit-for-purpose. The BPF will also serve as a measurement tool for IOF to award ‘Capture the Fracture Best Practice Recognition’ to celebrate successful FLS worldwide and drive service development in areas of unmet need. The Capture the Fracture website will provide a suite of resources related to FLS and secondary fracture prevention, which will be updated as new materials become available. A mentoring programme will enable those in the early stages of development of FLS to learn from colleagues elsewhere that have achieved Best Practice Recognition. A grant programme is in development to aid clinical systems which require financial assistance to establish FLS in their localities. Conclusion Nearly half a billion people will reach retirement age during the next 20 years. IOF has developed Capture the Fracture because this is the single most important thing that can be done to directly improve patient care, of both women and men, and reduce the spiralling fracture-related care costs worldwide.</p

    Role of microbial biofilms in the maintenance of oral health and in the development of dental caries and periodontal diseases. Consensus report of group 1 of the Joint EFP/ORCA workshop on the boundaries between caries and periodontal disease.

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    BACKGROUND AND AIMS: The scope of this working group was to review (1) ecological interactions at the dental biofilm in health and disease, (2) the role of microbial communities in the pathogenesis of periodontitis and caries, and (3) the innate host response in caries and periodontal diseases. RESULTS AND CONCLUSIONS: A health-associated biofilm includes genera such as Neisseria, Streptococcus, Actinomyces, Veillonella and Granulicatella. Microorganisms associated with both caries and periodontal diseases are metabolically highly specialized and organized as multispecies microbial biofilms. Progression of these diseases involves multiple microbial interactions driven by different stressors. In caries, the exposure of dental biofilms to dietary sugars and their fermentation to organic acids results in increasing proportions of acidogenic and aciduric species. In gingivitis, plaque accumulation at the gingival margin leads to inflammation and increasing proportions of proteolytic and often obligately anaerobic species. The natural mucosal barriers and saliva are the main innate defence mechanisms against soft tissue bacterial invasion. Similarly, enamel and dentin are important hard tissue barriers to the caries process. Given that the present state of knowledge suggests that the aetiologies of caries and periodontal diseases are mutually independent, the elements of innate immunity that appear to contribute to resistance to both are somewhat coincidental
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