6,419 research outputs found

    Discontinuous Galerkin Methods for Mass Transfer through Semi-Permeable Membranes

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    A discontinuous Galerkin (dG) method for the numerical solution of initial/boundary value multi-compartment partial differential equation (PDE) models, interconnected with interface conditions, is presented and analysed. The study of interface problems is motivated by models of mass transfer of solutes through semi-permeable membranes. More specifically, a model problem consisting of a system of semilinear parabolic advection-diffusion-reaction partial differential equations in each compartment, equipped with respective initial and boundary conditions, is considered. Nonlinear interface conditions modelling selective permeability, congestion and partial reflection are applied to the compartment interfaces. An interior penalty dG method is presented for this problem and it is analysed in the space-discrete setting. The a priori analysis shows that the method yields optimal a priori bounds, provided the exact solution is sufficiently smooth. Numerical experiments indicate agreement with the theoretical bounds and highlight the stability of the numerical method in the advection-dominated regime

    Forecasting transitions in systems with high dimensional stochastic complex dynamics: A Linear Stability Analysis of the Tangled Nature Model

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    We propose a new procedure to monitor and forecast the onset of transitions in high dimensional complex systems. We describe our procedure by an application to the Tangled Nature model of evolutionary ecology. The quasi-stable configurations of the full stochastic dynamics are taken as input for a stability analysis by means of the deterministic mean field equations. Numerical analysis of the high dimensional stability matrix allows us to identify unstable directions associated with eigenvalues with positive real part. The overlap of the instantaneous configuration vector of the full stochastic system with the eigenvectors of the unstable directions of the deterministic mean field approximation is found to be a good early-warning of the transitions occurring intermittently.Comment: 4 pages and 4 figures - The new version contains a corrected Figure

    Connecting the Micro-dynamics to the Emergent Macro-variables: Self-Organized Criticality and Absorbing Phase Transitions in the Deterministic Lattice Gas

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    We reinvestigate the Deterministic Lattice Gas introduced as a paradigmatic model of the 1/f spectra (Phys. Rev. Lett. V26, 3103 (1990)) arising according to the Self-Organized Criticality scenario. We demonstrate that the density fluctuations exhibit an unexpected dependence on systems size and relate the finding to effective Langevin equations. The low density behavior is controlled by the critical properties of the gas at the absorbing state phase transition. We also show that the Deterministic Lattice Gas is in the Manna universality class of absorbing state phase transitions. This is in contrast to expectations in the literature which suggested that the entirely deterministic nature of the dynamics would put the model in a different universality class. To our knowledge this is the first fully deterministic member of the Manna universality class.Comment: 8 pages, 12 figures. Changes in the new version: Reference list has been correcte

    What is the Meaning of Mindful Practice Among Practitioners?

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    This study explored the meaning of mindful practice and the influences practitioner\u27s personal use and training had in the therapeutic setting, as well as with client outcomes. Qualitative methods were used to recruit and interview licensed practitioners with a personal practice of mindfulness. Six participants responded to interview questions in person, over the phone, or by email. Using grounded theory and open coding, six themes were identified: (a) Definitions of Mindful Practice; (b) Practitioner\u27s Training and Personal Use of Mindful Practice: The Effects on Client Outcome; (c) Practitioner\u27s Personal Mindful Practice: The Effects on Client-Centered Presence; (d) Practitioner\u27s Support of Client in Mindful Practice; (e) Positive Effects of Therapeutic Mindful Practice; and (f) Insights and Concerns. A discussion of how these themes relate back to literature is presented. The implications for social work practice, research, and social policy are: (a) Mindful practice training and education for social work students, (b) Insight into the uses and benefits of therapeutic mindful practice, (c) Preservation of the integrity of mindful practice, (d) Upholding ethical principles of mindful practice, (e) Understanding the significance mindful practice has with the practitioner and client, and (f) Requiring mindfulness skills to be taught in health and physical education classes from preschool through high school

    The evolving role of customer focus in quality management: Using customer feedback to mobilize quality improvements in the age of digitalization and increased service delivery

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    Understanding customer needs is fundamental for being able to deliver high quality products and services, and, as a result, maintain and improve customer satisfaction. Achieving this has become a challenge, as rapid technological developments, market saturation, and increasingly skilled competition from low-cost economies have led to progressively more complex customer needs. In addition, more manufacturing firms are offering services, thus shifting the focus from merely providing a physical product to also providing services. These changes result in an array of challenges for quality management regarding how to manage the integrated duality of product and service quality. Consequently, the need for quality management to understand how customers perceive the quality of the firmā€™s offering is becoming increasinglyimportant, as merely focusing on technical product quality improvements is insufficient. Compiling five papers, based on four studies across both manufacturing and service industries, this thesis outlines the evolving role of quality management in the age of digitalization and increased service delivery, by exploring the use of customer feedback for quality improvements in both products and services.First, the thesis identifies the prerequisites needed to use customer feedback for quality improvements, identifying the importance of access to the different interfaces through which customer feedback emerges. These interfaces are growing in number and complexity as digitalization and increased service delivery reshape how firms and customers interact and how offerings are delivered. Second, the capacities needed to mobilize customer feedback for quality improvements are explored using the concept of absorptive capacity, which describes the capacity to acquire and use external information. The studied firms are found to have underdeveloped absorptive capacity in terms of mobilizing customer feedback regarding service quality compared to mobilizing customer feedback on product quality. Third, the evolving boundaries and scope of quality management, driven by digitalization and increased service delivery, require quality management to go from reactive and inward-focused to embracing a proactive, continuous, and customer-focused way of working. Furthermore, the abundance of codified customer feedback in the form of big data readily available for firms today, leads to the risk of predominantly focusing on technical quality aspects while neglecting more intangible quality elements. The importance of integrating small data into firm efforts to manage quality is therefore key to ensuring quality improvements encompass the entire customer experience. Conclusively, the evolving role of customer focus in quality management requires the reconceptualization of quality to quality-in-use, and the development of both the capturing and the converting roles of quality management in terms of mobilizing customer feedback for both quality improvements and increased customer knowledge

    What is the Meaning of Mindful Practice Among Practitioners?

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    This study explored the meaning of mindful practice and the influences practitioner\u27s personal use and training had in the therapeutic setting, as well as with client outcomes. Qualitative methods were used to recruit and interview licensed practitioners with a personal practice of mindfulness. Six participants responded to interview questions in person, over the phone, or by email. Using grounded theory and open coding, six themes were identified: (a) Definitions of Mindful Practice; (b) Practitioner\u27s Training and Personal Use of Mindful Practice: The Effects on Client Outcome; (c) Practitioner\u27s Personal Mindful Practice: The Effects on Client-Centered Presence; (d) Practitioner\u27s Support of Client in Mindful Practice; (e) Positive Effects of Therapeutic Mindful Practice; and (f) Insights and Concerns. A discussion of how these themes relate back to literature is presented. The implications for social work practice, research, and social policy are: (a) Mindful practice training and education for social work students, (b) Insight into the uses and benefits of therapeutic mindful practice, (c) Preservation of the integrity of mindful practice, (d) Upholding ethical principles of mindful practice, (e) Understanding the significance mindful practice has with the practitioner and client, and (f) Requiring mindfulness skills to be taught in health and physical education classes from preschool through high school

    Young Binary Stars and Associated Disks

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    The typical product of the star formation process is a binary star. Binaries have provided the first dynamical measures of the masses of pre-main-sequence (PMS) stars, providing support for the calibrations of PMS evolutionary tracks. Surprisingly, in some star-forming regions PMS binary frequencies are higher than among main-sequence solar-type stars. The difference in PMS and main-sequence binary frequencies is apparently not an evolutionary effect; recent attention has focussed on correlations between binary frequency and stellar density or cloud temperatures. Accretion disks are common among young binary stars. Binaries with separations between 1 AU and 100 AU have substantially less submillimeter emission than closer or wider binaries, suggesting that they have truncated their disks. Evidence of dynamical clearing has been seen in several binaries. Remarkably, PMS binaries of all separations show evidence of circumstellar disks and continued accretion. This suggests that the circumstellar disks are replenished from circumbinary disks or envelopes. The frequent presence of disks suggests that planet formation can occur in binary environments, and formation of planets in wide binaries is already established by their discovery. Circumbinary disk masses around very short period binaries are ample to form planetary systems such as our own. The nature of planetary systems among the most common binaries, with separations between 10 AU and 100 AU, is less clear given the observed reduction in disk mass, though they may have disk masses adequate for the formation of terrestrial-like planets.Comment: 32 pages, including 6 Postscript figures (TeX, uses psfig.sty); to appear in "Protostars & Planets IV". Gif figures with captions and high-res Postscript color figure available at http://hven.swarthmore.edu/~jensen/preprints/ppiv.htm

    Development of a Memory Training Game

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    German and Israeli Innovation: The Best of Two Worlds

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    This study reviews ā€“ through desk research and expert interviews with Mittelstand companies, startups and ecosystem experts ā€“ the current status of the Israeli startup ecosystem and the Mittelstand region of North Rhine- Westphalia (NRW), Germany. As a case study, it highlights potential opportunities for collaboration and analyzes different engagement modes that might serve to connect the two regions. The potential synergies between the two economies are based on a high degree of complementarity. A comparison of NRWā€™s key verticals and Israelā€™s primary areas of innovation indicates that there is significant overlap in verticals, such as artificial intelligence (AI), the internet of things (IoT), sensors and cybersecurity. Israeli startups can offer speed, agility and new ideas, while German Mittelstand companies can contribute expertise in production and scaling, access to markets, capital and support. The differences between Mittelstand companies and startups are less pronounced than those between startups and big corporations. However, three current barriers to fruitful collaboration have been identified: 1) a lack of access, 2) a lack of transparency regarding relevant players in the market, and 3) a lack of the internal resources needed to select the right partners, often due to time constraints or a lack of internal expertise on this issue. To ensure that positive business opportunities ensue, Mittelstand companies and startups alike have to be proactive in their search for cooperation partners and draw on a range of existing engagement modes (e.g., events, communities, accelerators). The interviews and the research conducted for this study made clear that no single mode of engagement can address all the needs and challenges associated with German-Israeli collaboration
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