Understanding dynamics using sensitivity analysis: caveat and solution

in BMC Systems Biology (2011), 5

BACKGROUND: Parametric sensitivity analysis (PSA) has become one of the most commonly used tools in computational systems biology, in which the sensitivity coefficients are used to study the parametric ... [more ▼]

BACKGROUND: Parametric sensitivity analysis (PSA) has become one of the most commonly used tools in computational systems biology, in which the sensitivity coefficients are used to study the parametric dependence of biological models. As many of these models describe dynamical behaviour of biological systems, the PSA has subsequently been used to elucidate important cellular processes that regulate this dynamics. However, in this paper, we show that the PSA coefficients are not suitable in inferring the mechanisms by which dynamical behaviour arises and in fact it can even lead to incorrect conclusions. RESULTS: A careful interpretation of parametric perturbations used in the PSA is presented here to explain the issue of using this analysis in inferring dynamics. In short, the PSA coefficients quantify the integrated change in the system behaviour due to persistent parametric perturbations, and thus the dynamical information of when a parameter perturbation matters is lost. To get around this issue, we present a new sensitivity analysis based on impulse perturbations on system parameters, which is named impulse parametric sensitivity analysis (iPSA). The inability of PSA and the efficacy of iPSA in revealing mechanistic information of a dynamical system are illustrated using two examples involving switch activation. CONCLUSIONS: The interpretation of the PSA coefficients of dynamical systems should take into account the persistent nature of parametric perturbations involved in the derivation of this analysis. The application of PSA to identify the controlling mechanism of dynamical behaviour can be misleading. By using impulse perturbations, introduced at different times, the iPSA provides the necessary information to understand how dynamics is achieved, i.e. which parameters are essential and when they become important. [less ▲]

Understanding the differences between how novice and experienced designers approach design tasks

in Research in Engineering Design (2003), 14(1), 1-11

Research was undertaken to understand how to provide the most appropriate support for novice designers in engineering design. However, how designers apply their experience and knowledge is not understood ... [more ▼]

Research was undertaken to understand how to provide the most appropriate support for novice designers in engineering design. However, how designers apply their experience and knowledge is not understood and further research in this area is required. This paper describes an observational study to understand how novice and experienced designers approach design tasks. [less ▲]

A unified enrichment approach addressing blending and conditioning issues in enriched finite elements

in Computer Methods in Applied Mechanics and Engineering (2019), 349

We present a combination of techniques to improve the convergence and conditioning properties of partition of unity (PU) enriched finite element methods. By applying these techniques to different types of ... [more ▼]

We present a combination of techniques to improve the convergence and conditioning properties of partition of unity (PU) enriched finite element methods. By applying these techniques to different types of enrichment functions, namely polynomial, discontinuous and singular, higher order convergence rates can be obtained while keeping condition number growth rates similar to the ones corresponding to standard finite elements. [less ▲]

Universal health coverage: an urgent need for collaborative learning and technology in primary care

in Education for Primary Care (2017)

Universal health coverage is an achievable goal for all health professionals globally. However, for it to be implemented technology and collaboration are essential. This letter focuses on recently ... [more ▼]

Universal health coverage is an achievable goal for all health professionals globally. However, for it to be implemented technology and collaboration are essential. This letter focuses on recently published recommendations for technology in primary care education in respect to Universal Health Coverage. [less ▲]

UNSUPERVISED LEARNING BASED MODEL ORDER REDUCTION FOR HYPERELASTOPLASTICITY

Presentation (2021, January)

Usage of Smartphone Data to Derive an Indicator for Collaborative Mobility between Individuals

in ISPRS International Journal of Geo-Information (2017), 6(3), 62

The potential of geospatial big data has been drawing attention for a few years. Despite the larger and larger market penetration of portable technologies (nomadic and wearable devices like smartphones ... [more ▼]

The potential of geospatial big data has been drawing attention for a few years. Despite the larger and larger market penetration of portable technologies (nomadic and wearable devices like smartphones and smartwatches), their opportunities for travel behavior analysis are still relatively unexplored. The main objective of our study is to extract the human mobility patterns from GPS traces in order to derive an indicator for enhancing Collaborative Mobility (CM) between individuals. The first step, extracting activity duration and location, is done using state-of-the-art automated recognition tools. Sensors data are used to reconstruct individual’s activity location and duration across time. For constructing the indicator, in a second step, we defined different variables and methods for specific case studies. Smartphone sensor data are being collected from a limited number of individuals and for one week. These data are used to evaluate the proposed indicator. Based on the value of the indicator, we analyzed the potential for identifying CM among groups of users, such as sharing traveling resources (e.g., carpooling, ridesharing, parking sharing) and time (rescheduling and reordering activities). [less ▲]

Using Bayes' theorem to infer the material parameters of human soft tissue

Presentation (2015, October 21)

Using Complex Problem Solving Simulations for General Cognitive Ability Assessment: the Genetics Lab Framework

in International Journal of Information Science and Intelligent System (2013), 2(4), 71-88

This paper presents the conception and operation of “the Genetics Lab,” a research platform designed for general intelligence measurement. This tool has been developed and refined to measure cognitive ... [more ▼]

This paper presents the conception and operation of “the Genetics Lab,” a research platform designed for general intelligence measurement. This tool has been developed and refined to measure cognitive skills of students in Luxembourg, Thanks to its generic and clear architecture, “the Genetics Lab” makes a major contribution by addressing technical weaknesses and flaws met with tools previously used to assess intelligence. This new platform can be used as groundwork for other evaluation solutions. In this paper, we explore in depth the main fields of e-assessment such as instructions, localized and multilingual content production and display, traces, and scoring. We also describe how the platform was put into action to create complex simulations and to make data collection resulting from the user’s test a flawless process. This paper is a continuation and extension of earlier work. [less ▲]

A UX Approach to Privacy and Security: the Impact of User, Contextual and System-Related Factors

in CHI Workshop Exploring Individual Diffferences in Privacy (2018, April)

This position paper lays out current and future studies which we conduct on the UX aspects of security and privacy, our goal being to understand which factors influence privacy-related decision-making. We ... [more ▼]

This position paper lays out current and future studies which we conduct on the UX aspects of security and privacy, our goal being to understand which factors influence privacy-related decision-making. We advocate using UX design methods in order to study interindividual differences, system-related and contextual factors involved in privacy and security attitudes and behaviors. These results will contribute to user-tailored and personalized privacy initiatives and guide the design of future technologies. [less ▲]

Value Stream Mapping (VSM) to Evaluate and Visualize Interrelated Process-Chains Regarding Circular Economy

in Advances in Production Management Systems. Artificial Intelligence for Sustainable and Resilient Production Systems (2021, August 31), 633

The concept of circular economy (CE) aims to close and slow resource loops without neglecting the goals of sustainable development. Recently, the concept received encouraging attention among researchers ... [more ▼]

The concept of circular economy (CE) aims to close and slow resource loops without neglecting the goals of sustainable development. Recently, the concept received encouraging attention among researchers and business experts to be a convenient solution to move away from the finite linear economy concept to a more sustainable solution. However, this change of paradigm is only possible if we consider systems in a holistic manner and can localize the preventing hurdles. Value stream mapping (VSM) is a commonly known lean method, used to develop current state visualization of product and information flows within organization, helping to seek weaknesses and improve process flows. The motivation of this paper is a new C-VSM model, which enables its users to evaluate and visualize connected process-chains regarding CE on different levels in a holistic manner. For this purpose, the traditional VSM model was adapted towards the needs and requirements of CE through the application of a new representation method, additional indicators, and an appropriated evaluation system. C-VSM is in line with the current political and industrial objectives to apply CE principles by enabling a holistic reflection and consideration of supply-chains (SCs) on different levels. The model itself is validated through an extensive cross-company case study. [less ▲]