1,302 research outputs found

    The influence of electron collisions on non-LTE Li line formation in stellar atmospheres

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    The influence of the uncertainties in the rate coefficient data for electron-impact excitation and ionization on non-LTE Li line formation in cool stellar atmospheres is investigated. We examine the electron collision data used in previous non-LTE calculations and compare them to recent calculations that use convergent close-coupling (CCC) techniques and to our own calculations using the R-matrix with pseudostates (RMPS) method. We find excellent agreement between rate coefficients from the CCC and RMPS calculations, and reasonable agreement between these data and the semi-empirical data used in non-LTE calculations up to now. The results of non-LTE calculations using the old and new data sets are compared and only small differences found: about 0.01 dex (~ 2%) or less in the abundance corrections. We therefore conclude that the influence on non-LTE calculations of uncertainties in the electron collision data is negligible. Indeed, together with the collision data for the charge exchange process Li(3s) + H Li^+ + H^- now available, and barring the existence of an unknown important collisional process, the collisional data in general is not a source of significant uncertainty in non-LTE Li line formation calculations.Comment: 8 pages, accepted by Astronomy and Astrophysics; Replaced with minor corrections following proof

    Paper 3: Selecting rapid review methods for complex questions related to health policy and system issues

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    Approaches for rapid reviews that focus on streamlining systematic review methods are not always suitable for exploring complex policy questions, as developing and testing theories to explain these complexities requires configuring diverse qualitative, quantitative, and mixed methods studies. Our objective was therefore to provide a guide to selecting approaches for rapidly (i.e., within days to months) addressing complex questions related to health policy and system issues. We provide a two-stage, transdisciplinary collaborative process to select a rapid review approach to address complex policy questions, which consists of scoping the breadth and depth of the literature and then selecting an optimal approach to synthesis. The first stage (scoping the literature) begins with a discussion with the stakeholders requesting evidence to identify and refine the question for the review, which is then used to conduct preliminary searches and conceptually map the documents identified. In the second stage (selection of an optimal approach), further stakeholder consultation is required to refine and tailor the question and approach to identifying relevant documents to include. The approach to synthesizing the included documents is then guided by the final question, the breadth and depth of the literature, and the time available and can include a static or evolving conceptual framework to code and analyze a range of evidence. For areas already covered extensively by existing systematic reviews, the focus can be on summarizing and integrating the review findings, resynthesizing the primary studies, or updating the search and reanalyzing one or more of the systematic reviews. The choice of approaches for conducting rapid reviews is intertwined with decisions about how to manage projects, the amount of work to be done, and the knowledge already available, and our guide offers support to help make these strategic decisions

    Parent Stars of Extrasolar Planets. XI. Trends with Condensation Temperature Revisited

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    We report the results of abundance analyses of new samples of stars with planets and stars without detected planets. We employ these data to compare abundance-condensation temperature trends in both samples. We find that stars with planets have more negative trends. In addition, the more metal-rich stars with planets display the most negative trends. These results confirm and extend the findings of Ramirez et al. (2009) and Melendez et al. (2009), who restricted their studies to solar analogs. We also show that the differences between the solar photospheric and CI meteoritic abundances correlate with condensation temperature.Comment: 7 pages, 11 figures; to be published in MNRA

    ISO/IEC 29110 and Software Engineering Education: A Systematic Mapping Study

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    Abstract: This article presents a study of the publications made on the ISO/IEC 29110 standard in the university context, especially from the perspective of software engineering education. ISO 29110 is a life cycle profiles for very small entities on systems and software engineering standard, published in many parts. ISO 29110, since its publication in 2011 and its continuous evolution to these days, is the subject of study in different contexts, with education being a relevant axis. Considering, that software engineering education has implications in the software industry in emerging countries, it is necessary to identify and consolidate the work done in this context. In this study, the main research question was what researches have been done at ISO 29110 in the training of software engineers? To answer this question, a systematic mapping study (SMS) was performed. In the SMS, 241 articles were obtained with search string and 17 of them became as primary study after a process selection. Based on these studies, it was possible to determine that the software engineering Basic profile of ISO 29110 and its processes (Project Management and Software Implementation) have been the most studied. Besides, it was identified that project-oriented learning and gamification techniques have been the most used ISO 29110 learning strategies in the training of future software industry professionals

    How Do Contextual Factors Influence Implementation and Receipt of Positive Youth Development Programs Addressing Substance Use and Violence? A Qualitative Meta-Synthesis of Process Evaluations

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    Objective:Positive youth development (PYD) often aims to prevent tobacco, alcohol, and drugs use and violence. We systematically reviewed PYD interventions, synthesizing process, and outcomes evidence. Synthesis of outcomes, published elsewhere, found no overall evidence of reducing substance use or violence but notable variability of fidelity. Our synthesis of process evaluations examined how implementation varied and was influenced by context.Data Source:Process evaluations of PYD aiming to reduce substance use and violence.Study Inclusion Criteria:Overall review published since 1985; written in English; focused on youth aged 11 to 18 years; focused on interventions addressing multiple positive assets; reported on theory, process, or outcomes; and concerned with reducing substance use or violence. Synthesis of process evaluations examined how implementation varies with or is influenced by context.Data Extraction:Two reviewers in parallel.Data Synthesis:Thematic synthesis.Results:We identified 12 reports. Community engagement enhanced program appeal. Collaboration with other agencies could broaden the activities offered. Calm but authoritative staff increased acceptability. Staff continuity underpinned diverse activities and durable relationships. Empowering participants were sometimes in tension with requiring them to engage in diverse activities.Conclusion:Our systematic review identified factors that might help improve the fidelity and acceptability of PYD interventions. Addressing these might enable PYD to fulfill its potential as a means of promoting health
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