354 research outputs found

    Juxtaposition of system dynamics and agent-based simulation for a case study in immunosenescence

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    Advances in healthcare and in the quality of life significantly increase human life expectancy. With the aging of populations, new un-faced challenges are brought to science. The human body is naturally selected to be well-functioning until the age of reproduction to keep the species alive. However, as the lifespan extends, unseen problems due to the body deterioration emerge. There are several age-related diseases with no appropriate treatment; therefore, the complex aging phenomena needs further understanding. It is known that immunosenescence is highly correlated to the negative effects of aging. In this work we advocate the use of simulation as a tool to assist the understanding of immune aging phenomena. In particular, we are comparing system dynamics modelling and simulation (SDMS) and agent-based modelling and simulation (ABMS) for the case of age-related depletion of naive T cells in the organism. We address the following research questions: Which simulation approach is more suitable for this problem? Can these approaches be employed interchangeably? Is there any benefit of using one approach compared to the other? Results show that both simulation outcomes closely fit the observed data and existing mathematical model; and the likely contribution of each of the naive T cell repertoire maintenance method can therefore be estimated. The differences observed in the outcomes of both approaches are due to the probabilistic character of ABMS contrasted to SDMS. However, they do not interfere in the overall expected dynamics of the populations. In this case, therefore, they can be employed interchangeably, with SDMS being simpler to implement and taking less computational resources

    Towards the development of a simulator for investigating the impact of people management practices on retail performance

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    ๏€Œ๏€‰๏€ž๏€„๏€‚ ๏€ˆ๏€„๏€๏€„๏€ˆ๏€‚ ๏€ ๏€Š๏€‚ ๏€‰๏€๏€Ž๏€ž๏€…๏€‰๏€“๏€ž๏€Œ๏€ ๏€•๏€‚ ๏€Š๏€ ๏€…๏€‚ ๏€‰๏€‚ ๏€Ž๏€ฃ๏€„๏€“๏€Œ๏€Š๏€Œ๏€“๏€‚ ๏€‰๏€ฃ๏€ฃ๏€ˆ๏€Œ๏€“๏€‰๏€ž๏€Œ๏€ ๏€•๏€‚ ๏€Œ๏€Ž๏€‚ ๏€ ๏€Š๏€ž๏€„๏€•๏€‚ ๏€ข๏€ ๏€…๏€„๏€‚ ๏€ ๏€Š๏€‚ ๏€‰๏€•๏€‚ ๏€‰๏€…๏€ž๏€‚ ๏€ž๏€™๏€‰๏€•๏€‚ ๏€‰๏€‚\ud ๏€Ž๏€“๏€Œ๏€„๏€•๏€“๏€„๏€›๏€‚๏€š๏€„๏€‚ ๏€™๏€‰๏€๏€„๏€‚ ๏€ฎ๏€„๏€๏€„๏€ˆ๏€ ๏€ฃ๏€„๏€ฎ๏€‚ ๏€‰๏€‚ ๏€…๏€„๏€ž๏€‰๏€Œ๏€ˆ๏€‚ ๏€๏€…๏€‰๏€•๏€“๏€™๏€‚ ๏€Ž๏€Œ๏€ข๏€ค๏€ˆ๏€‰๏€ž๏€Œ๏€ ๏€•๏€‚๏€ข๏€ ๏€ฎ๏€„๏€ˆ๏€‚ ๏€ž๏€ ๏€‚ ๏€Œ๏€•๏€๏€„๏€Ž๏€ž๏€Œ๏€œ๏€‰๏€ž๏€„๏€‚๏€‘๏€™๏€Œ๏€“๏€™๏€‚ ๏€ˆ๏€„๏€๏€„๏€ˆ๏€‚ ๏€ ๏€Š๏€‚\ud ๏€ข๏€ ๏€ฎ๏€„๏€ˆ๏€‚๏€‰๏€“๏€“๏€ค๏€…๏€‰๏€“๏€Ÿ๏€‚๏€Œ๏€Ž๏€‚๏€…๏€„๏€ณ๏€ค๏€Œ๏€…๏€„๏€ฎ๏€‚๏€Š๏€ ๏€…๏€‚๏€Ž๏€ค๏€“๏€™๏€‚๏€‰๏€‚๏€ข๏€ ๏€ฎ๏€„๏€ˆ๏€‚๏€ž๏€ ๏€‚๏€ ๏€๏€ž๏€‰๏€Œ๏€•๏€‚๏€ข๏€„๏€‰๏€•๏€Œ๏€•๏€œ๏€Š๏€ค๏€ˆ๏€‚๏€…๏€„๏€Ž๏€ค๏€ˆ๏€ž๏€Ž๏€‚๏€Š๏€ ๏€…๏€‚๏€ฃ๏€…๏€‰๏€“๏€ž๏€Œ๏€ž๏€Œ๏€ ๏€•๏€„๏€…๏€Ž๏€›

    A systems biology approach reveals major metabolic changes in the thermoacidophilic archaeon Sulfolobus solfataricus in response to the carbon source L-fucose versus D-glucose

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    Archaea are characterised by a complex metabolism with many unique enzymes that differ from their bacterial and eukaryotic counterparts. The thermoacidophilic archaeon Sulfolobus solfataricus is known for its metabolic versatility and is able to utilize a great variety of different carbon sources. However, the underlying degradation pathways and their regulation are often unknown. In this work, we analyse growth on different carbon sources using an integrated systems biology approach. The comparison of growth on L-fucose and D-glucose allows first insights into the genome-wide changes in response to the two carbon sources and revealed a new pathway for L-fucose degradation in S. solfataricus. During growth on L-fucose we observed major changes in the central carbon metabolic network, as well as an increased activity of the glyoxylate bypass and the 3-hydroxypropionate/4-hydroxybutyrate cycle. Within the newly discovered pathway for L-fucose degradation the following key reactions were identified: (i) L-fucose oxidation to L-fuconate via a dehydrogenase, (ii) dehydration to 2-keto-3-deoxy-L-fuconate via dehydratase, (iii) 2-keto-3-deoxy-L-fuconate cleavage to pyruvate and L-lactaldehyde via aldolase and (iv) L-lactaldehyde conversion to L-lactate via aldehyde dehydrogenase. This pathway as well as L-fucose transport shows interesting overlaps to the D-arabinose pathway, representing another example for pathway promiscuity in Sulfolobus species

    Towards an improved understanding of biogeochemical processes across surface-groundwater interactions in intermittent rivers and ephemeral streams

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    Surface-groundwater interactions in intermittent rivers and ephemeral streams (IRES), waterways which do not flow year-round, are spatially and temporally dynamic because of alternations between flowing, non-flowing and dry hydrological states. Interactions between surface and groundwater often create mixing zones with distinct redox gradients, potentially driving high rates of carbon and nutrient cycling. Yet a complete understanding of how underlying biogeochemical processes across surface-groundwater flowpaths in IRES differ among various hydrological states remains elusive. Here, we present a conceptual framework relating spatial and temporal hydrological variability in surface water-groundwater interactions to biogeochemical processing hotspots in IRES. We combine a review of theIRES biogeochemistry literature with concepts of IRES hydrogeomorphology to: (i) outline common distinctions among hydrological states in IRES; (ii) use these distinctions, together with considerations of carbon, nitrogen, and phosphorus cycles within IRES, to predict the relative potential for biogeochemical processing across different reach-scale processing zones (flowing water, fragmented pools, hyporheic zones, groundwater, and emerged sediments); and (iii) explore the potential spatial and temporal variability of carbon and nutrient biogeochemical processing across entire IRES networks. Our approach estimates the greatest reach-scale potential for biogeochemical processing when IRES reaches are fragmented into isolated surface water pools, and highlights the potential of relatively understudied processing zones, such as emerged sediments. Furthermore, biogeochemical processing in fluvial networks dominated by IRES is likely more temporally than spatially variable. We conclude that biogeochemical research in IRES would benefit from focusing on interactions between different nutrient cycles, surface-groundwater interactions in non-flowing states, and consideration of fluvial network architecture. Our conceptual framework outlines opportunities to advance studies and expand understanding of biogeochemistry in IRES

    Participatory citizenship: critical perspectives on client-centred occupational therapy

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    Background/aims: This article aims to discuss client-centred practice, the current dominant approach within occupational therapy, in relation to participatory citizenship. Occupational therapists work within structures and policies that set boundaries on their engagement with clients, while working with complex, multidimensional social realities. Methods: The authors present a critical discussion shaped by their research, including a survey, discussions at workshops at international conferences, and critical engagement with the literature on occupational therapy, occupation, and citizenship. Conclusion: A focus on citizenship suggests reframing professional development based on the participation in public life of people as citizens of their society. While occupational therapists often refer to clients in the context of communities, groups, families, and wider society, the term client centred practice typically represents a particular view of the individual and may sometimes be too limited in application for a more systemic and societal approach. Significance: The authors question the individual focus which has, until recently, been typical of client-centred occupational therapy. Placing citizenship at the core of intervention is a transformative process that assumes all people are citizens and conceives of health as a collective issue, influencing the way we educate, do research, and practise. Key words: Collective, dis-citizenship, inequalities, professional development, participation, paradigms, occupational justice</p
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