310,525 research outputs found

    Engineering simulations for cancer systems biology

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    Computer simulation can be used to inform in vivo and in vitro experimentation, enabling rapid, low-cost hypothesis generation and directing experimental design in order to test those hypotheses. In this way, in silico models become a scientific instrument for investigation, and so should be developed to high standards, be carefully calibrated and their findings presented in such that they may be reproduced. Here, we outline a framework that supports developing simulations as scientific instruments, and we select cancer systems biology as an exemplar domain, with a particular focus on cellular signalling models. We consider the challenges of lack of data, incomplete knowledge and modelling in the context of a rapidly changing knowledge base. Our framework comprises a process to clearly separate scientific and engineering concerns in model and simulation development, and an argumentation approach to documenting models for rigorous way of recording assumptions and knowledge gaps. We propose interactive, dynamic visualisation tools to enable the biological community to interact with cellular signalling models directly for experimental design. There is a mismatch in scale between these cellular models and tissue structures that are affected by tumours, and bridging this gap requires substantial computational resource. We present concurrent programming as a technology to link scales without losing important details through model simplification. We discuss the value of combining this technology, interactive visualisation, argumentation and model separation to support development of multi-scale models that represent biologically plausible cells arranged in biologically plausible structures that model cell behaviour, interactions and response to therapeutic interventions

    A Study of the Role of Organized Structures in Jet Noise Generation

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    We present analytical, experimental and computational studies aimed at understanding the role of large-scale, organized structures in noise generation from high-speed, compressible jets. Two-point near-field pressure data from experiments are analyzed and used to identify parameters in a wave-packet based model for noise generation from organized, large-scale structures. The statistical spectrum of far field pressure is expressed in terms of two-point space-time correlations of the near-field pressure on a surface enclosing the jet. The surface is assumed to be sufficiently near the turbulent region tobe dominated by non-propagating hydrodynamic disturbances, yet sufficiently far such that linear behavior can be assumed in extending the near-field pressure to the far field. Validity of such assumptions is investigated by interrogating the jet DNS database of Freund [J. Fluid Mech. 438:277-305 2001]. The DNS data analysis is also used to investigate the impact of limited spatial resolution in the experiments. The analytical model is used to study far field noise generation from organized structures. Results show that, for sufficiently short structure lifetime, aft angle far field pressure spectra tend to exhibit frequency scaling with Helmholtz number, rather than Strouhal number

    Impact Evaluations and Development: Nonie Guidance on Impact Evaluation

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    In international development, impact evaluation is principally concerned with final results of interventions (programs, projects, policy measures, reforms) on the welfare of communities, households, and individuals, including taxpayers and voters. Impact evaluation is one tool within the larger toolkit of monitoring and evaluation (including broad program evaluations, process evaluations, ex ante studies, etc.).The Network of Networks for Impact Evaluation (NONIE) was established in 2006 to foster more and better impact evaluations by its membership -- the evaluation networks of bilateral and multilateral organizations focusing on development issues, as well as networks of developing country evaluators. NONIE's member networks conduct a broad set of evaluations, examining issues such as project and strategy performance, institutional development, and aid effectiveness. By sharing methodological approaches and promoting learning by doing on impact evaluations, NONIE aims to promote the use of this more specific approach by its members within their larger portfolio of evaluations. This document, by Frans Leeuw and Jos Vaessen, has been developed to support this focus.For development practitioners, impact evaluations play a keyrole in the drive for better evidence on results and development effectiveness. They are particularly well suited to answer important questions about whether development interventions do or do not work, whether they make a difference, and how cost-effective they are. Consequently, they can help ensure that scarce resources are allocated where they can have the most developmental impact

    Fundamental concepts in management research and ensuring research quality : focusing on case study method

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    This paper discusses fundamental concepts in management research and ensuring research quality. It was presented at the European Academy of Management annual conference in 2008

    Evaluation in the practice of development

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    Knowledge about development effectiveness is constrained by two factors. First, the project staff in governments and international agencies who decide how much to invest in research on specific interventions are often not well informed about the returns to rigorous evaluation and (even when they are)cannot be expected to take full account of the external benefits to others from new knowledge. This leads to under-investment in evaluative research. Second, while standard methods of impact evaluation are useful, they often leave many questions about development effectiveness unanswered. The paper proposes ten steps for making evaluations more relevant to the needs of practitioners. It is argued that more attention needs to be given to identifying policy-relevant questions (including the case for intervention); that a broader approach should be taken to the problems of internal validity; and that the problems of external validity (including scaling up) merit more attention.Poverty Monitoring&Analysis,Science Education,Scientific Research&Science Parks,Population Policies,Tertiary Education

    Measuring the Impact of Youth Voluntary Service Programs

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    Summary and Conclusions of a meeting of international experts hosted by the World Bank and Innovations in Civic Participation to discuss evaluation of the impact of youth civic engagement on development
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