Christen, Patrik

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Christen
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Patrik
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Patrik Christen

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2018 - 20194
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Enddatum: 2019 ×

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Gerade angezeigt 1 - 4 von 4
  • Vorschaubild nicht verfügbar
    Publikation
    Cybernetical concepts for cellular automaton and artificial neural network modelling and implementation
    (IEEE, 2019) Christen, Patrik; Del Fabbro, Olivier [in: 2019 IEEE International Conference on Systems, Man and Cybernetics (SMC)]
    As a discipline cybernetics has a long and rich history. In its first generation it not only had a worldwide span, in the area of computer modelling, for example, its proponents such as John von Neumann, Stanislaw Ulam, Warren McCulloch and Walter Pitts, also came up with models and methods such as cellular automata and artificial neural networks, which are still the foundation of most modern modelling approaches. At the same time, cybernetics also got the attention of philosophers, such as the Frenchman Gilbert Simondon, who made use of cybernetical concepts in order to establish a metaphysics and a natural philosophy of individuation, giving cybernetics thereby a philosophical interpretation, which he baptised allagmatic. In this paper, we emphasise this allagmatic theory by showing how Simondon’s philosophical concepts can be used to formulate a generic computer model or metamodel for complex systems modelling and its implementation in program code, according to generic programming. We also present how the developed allagmatic metamodel is capable of building simple cellular automata and artificial neural networks.
    04B - Beitrag Konferenzschrift
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    Publikation
    Virtual supersampling as post-processing step preserves the trabecular bone morphometry in human peripheral quantitative computed tomography scans
    (Public Library of Science, 2019) Schulte, Friederike A.; Christen, Patrik; Badilatti, Sandro D.; Parkinson, Ian; Khosla, Sundeep; Goldhahn, Jörg; Müller, Ralph [in: PLOS ONE]
    In the clinical field of diagnosis and monitoring of bone diseases, high-resolution peripheral quantitative computed tomography (HR-pQCT) is an important imaging modality. It provides a resolution where quantitative bone morphometry can be extracted in vivo on patients. It is known that HR-pQCT provides slight differences in morphometric indices compared to the current standard approach micro-computed tomography (micro-CT). The most obvious reason for this is the restriction of the radiation dose and with this a lower image resolution. With advances in micro-CT evaluation techniques such as patient-specific remodeling simulations or dynamic bone morphometry, a higher image resolution would potentially also allow the application of such novel evaluation techniques to clinical HR-pQCT measurements. Virtual supersampling as post-processing step was considered to increase the image resolution of HR-pQCT scans. The hypothesis was that this technique preserves the structural bone morphometry. Supersampling from 82
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild nicht verfügbar
    Publikation
    Moving beyond the genome with computer modeling
    (Future Medicine, 2018) Christen, Patrik [in: Personalized Medicine]
    Once personalized computer simulations can provide the appropriate models and explanations to model biological and mechanical processes, we will be able to move beyond genome-based personalized medicine, enabling better use of the valuable medical data.
    01A - Beitrag in wissenschaftlicher Zeitschrift
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    Publikation
    Least-detectable and age-related local in vivo bone remodelling assessed by time-lapse HR-pQCT
    (Public Library of Science, 2018) Christen, Patrik; Boutroy, Stephanie; Ellouz, Rafaa; Chapurlat, Roland; Rietbergen, Bert van [in: PLOS ONE]
    We previously developed an image analysis approach for the determination of local sites of bone remodelling using time-lapse in vivo HR-pQCT. The involved image filtering for removing noise was chosen rather aggressively, and also removed some effects of the bone remodelling. In this paper, we quantify these filtering settings using ex vivo reproducibility HR-pQCT images, and determine the least-detectable bone remodelling using in vivo reproducibility HR-pQCT images, as well as testing whether the approach is capable of capturing age-related bone remodelling by use of in vivo long-term HR-pQCT images. We found that a threshold value of 225 mg HA/cm3 for the filtering led to acceptable results with falsely determined bone remodelling of less than 0.5%, and that the least-detectable bone formation and bone resorption are 2.0 ± 1.0% and 2.2 ± 0.7% respectively. We also found that age-related local bone remodelling can be captured satisfactorily in postmenopausal women. The latter revealed new insights into the effect of ageing on bone remodelling, and showed that bone remodelling seems to take place through a few small formation packets and many large resorption volumes leading to a net bone loss. We conclude that local in vivo bone remodelling can be successfully assessed with time-lapse in vivo HR-pQCT capable of assessing age-related changes in bone remodelling.
    01A - Beitrag in wissenschaftlicher Zeitschrift